Klaus' Lens Problem
Page (photo-illustrated)
I thought I would offer my own hierarchy of lens faults and their
probable impact.
| Shoptalk - N. Goldberg Oct. 1974 p.72 Popular Photography |
|---|
| Speaking of grease, a single greasy fingerprint on a lens can knock down the contrast level of the image it forms by as much as 20 percent. Some fingerprints are more watery than oily, and in many cases, the acids in the watery fingerprint can etch the glass surface if allowed to remain there. |
A chip is a spawled piece of glass, usually near the lens edge. Stopping
down may minimize the impact and reduce flare from lens edge defects.
Chips may hide fractures which penetrate farther into the lens than the
visible damage lines. Lens stresses during use may expand the size of
these hidden defects and their on-film impact. Cycles of heating and
contracting from cold may also cause further cracking and deterioration.
Speaking of impact, both lens chips and gouges are direct evidence of abuse and possible lens mis-alignment clues. Carefully test, and expect a large price discount!
Early
on, the fungus can be removed before it does major damage by disassembly
and cleaning by a camera repairperson. Direct exposure to ultraviolet
light is reported to kill fungus too.
After a while, the fungus actually etches a pattern into the lens surface. It is like a fingerprint, only potentially even worse in its adverse effects on contrast. Usually, the cost to fix the lens once it has become etched by fungus is so high as to be uneconomic.
Some problems are not really problems, but many people think they are.
Uncoated lenses can give good performance, especially if they are carefully controlled in flare prone situations (see hints above).
Some modest improvements in flare control and contrast result from using
multi-coated versus the older single coated lens designs. In one Popular
Photography comparison of similar speed and focal length lenses from
Pentax, the multi-coated lenses reduced flare from circa 1.6 per cent on
the single coated lens to circa 0.9 per cent on the multi-coated lens. An
uncoated lens had flare in the 3 to 5 per cent range.
A zoom
lens has more surfaces by far than most older lenses, so a typical
zoom really does need multicoated lens surfaces to perform well in flare
producing situations.
So most 20th century lenses will do a decent job with color film, but there are exceptions. Some lenses are highly corrected for bringing all colors to the same film plane, called apochromats. By contrast, some achromatic lenses ignored some colors (red) in their formulations, being designed for non-panchromatic films.
On the other hand, many older lenses perform remarkably well, and yield
results very nearly as good as their much more expensive current
versions. Some lens designs haven't changed in decades (e.g., nikkor
105mm f2.5 lens). Studies of comparative ratings and tests can often
identify particular lenses which are just as effective and far less
costly than the latest lenses for the intended usage.
Various lens rating services online
provide reviews of these built-in design tradeoffs and optical limitations.
The more you pay, the more you hope these optical defects are minimized
and quality control is maintained. When buying used lenses, you should
check the individual lens out with film (as described in camera and lens testing article). Even
the most costly lens could have been knocked out of alignment, so don't
rely on brand name to obviate the need for testing the lens carefully.
see Top Ten Myths of Photography
Hopefully, the ideas and opinions shared here may suggest some opportunities while warning of some problems to be considered in your selection and choice of lenses. Many good performing lenses with minor but visible defects are sold at huge discounts. The techniques and tests described in this article (and related camera and lens testing article) will help you locate some good buys and avoid problems in your photo purchases. Good Luck!
Aberrations
Lens design is a tradeoff, so you can't eliminate all aberrations
entirely, and costs go up rapidly the more you improve optical qualities.
Electronic Bench Test
Photonics are used to compare contrast levels electronically, using fine
and coarse slits, in a relatively objective measure of lens contrast
Manufacturing Defects
Defects such as mis-centered elements will reduce lens performance,
perhaps significantly. Amateur lens 'repairs' can induce similar
problems.
Star Test
The image of a point of light is examined under a microscope, any
deviation from ideal shows the nature and degree of aberration. As with
most lens tests, this one depends on experience and subjective factors.
NOT IMPROVED BY STOPPING DOWN:
Curvature of Field
Inability to bring all points on a flat object into focus on a flat image
or film plane; not improved by stopping down.
Longitudinal Chromatic Aberration
As the color of light changes, the focus shifts; this aberration is not
improved by stopping down.
Distortion
Image lines of a square bows out (barrel type) or in (pincushion type);
doesn't influence sharpness; isn't improved by stopping down.
Lateral Chromatic Aberration
The degree of magnification varys as the color of the light varys; this
aberration is not improved by stopping down.
Spherical Aberration
Spherical aberrations cause a shift in focus as you stop the lens down or
open up.
IMPROVED BY STOPPING DOWN:
Astigmatism
Lines radial to the optical axis focus in a different plane than lines
perpendicular to the radial lines. Astigmatism is improved by stopping
down.
Coma
Off-axis points show as tear-drop shapes instead of round points;
improved by stopping down.
Flare
Reduces contrast, may be improved by stopping down, depending on source.
Optimium Aperture
Point beyond which no further improvement in image contrast can be seen,
e.g. when stopping down.
Vignetting
Corners of film are under-exposed; improved by stopping down.
Adapted from Anonymous, Lens Test Glossary, p. 24, May 1973, Pop.
Photography.
See also Focus shift posting below.
Notes:
MP april 1966 p. 16 Keppler on the SLR
From Modern Photography, April, 1966, H. Keppler, SLR column, p. 16:
Inexpensive lenses are surprisingly well color-corrected. Their faults
are generally not along these lines.
First of all, there seems to be an erroneous assumption that cheap - er -
inexpensive lenses are not properly color corrected and may do well for
black and white but will certainly fall down when it comes to shooting
color. Actually, this just isn't so.
From Modern Photography, June 1965, Bennett Sherman, Techniques Tomorrow, p.31:
What about the difference between the popularly priced lens and the very
expensive one? First of all, there is not a very great difference between
the optical performance. Most lenses are very nearly the same optical
designs, such as the familiar Biotar types. In the expensive lens, an
extra effort is made to keep the focal length of the manufactured lens
very close to the design value. In the less expensive types, the focal
length may vary a bit more. There can also be a small variation in the
correction qualities for close ups, and the less expensive lens might show
a bit more variation of sharpness at various apertures. You'll probably
never notice it in everyday shooting, but careful testing including
resolution charts, can show up these slight differences. Because of close
tolerances in manufacturing and testing, the more expensive optics show
a greater uniformity of performance, lens to lens. [italics in
original] In any case, careful testing can tell you what to expect from
your lens, and quickly identify a clunker.
Related Postings:
From: jbh@magicnet.net (John Hicks)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Perceived lens problem
Date: 3 Feb 1998
Darrell Messenger dmess@iu.net wrote:
Yesterday I bought a f8/90mm Super-Angulon ... (with dust..)
Don't worry about it; the dust won't cause any problems unless
there's really lots of it.
jbh
rec.photo.equipment.large-format
From: dickburk@ix.netcom.com (Richard Knoppow)
[1] Re: Advice needed on scratched lens
Date: Fri Feb 06
Sven Sampson sven@slip.net wrote:
I just received a used 16.5" Goerz APO RD Artar in barrel
that I was planning to send off to Steve Grimes for mounting.
I air dusted it, brushed it with a camel hair brush and then
used Kodak lens cleaning paper and a photographic
lens cleaning solution to gently clean up the lens surfaces.
The front and back of the rear element are very clean. The
rear of the front element is very clean. The front of front
element has a very fine, but pervasive, circular network of
scratches on it with a heavier concentration near the center
of the lens.
My question is:
1) How much should this affect the lens performance ( I was
planning on using it as a long lens on 4x5)?
I am trying to decide if I should return
the lens and start looking for another, or if this will work well as is.
Thanks in advance for your thoughts.
Sven
Its impossible to know for sure without seeing the lens. However,
although others may disagree with me I think this kind of scratching
acts a lot like a diffusion filter on the lens and lowers its
contrast. If its bad enough it will but halos around highlights. A
couple or three shallow scratches aren't a big deal but this sort of
thing is likely to be. Really the only way to tell how much
degradation there is is to compare it with an undamaged lens.
If you are going to spend the money to have a lens mounted in a
shutter I would insist on an undamaged one. I suggest you return it
and look for another. There are plenty of Red Dots around just now at
reasonable prices.
---
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
rec.photo.misc #59237
From: "Kirk R. Darling" kdarling@ix.netcom.com
[1] Re: Suggestions to avoid mildew growth on lenses
Date: Mon Feb 16 1998
A ventilated cabinet with an incandescent light has been used for decades
by photographers in the tropics, and I can testify myself that it worked
for me in the Philippines. Simple, low tech, zero maintainance, as long as
one can afford to keep a 60-watt lamp burning 8-10 hours a day.
Two things favor mold and mildew the most:
1) Moisture. Silica gel can only be used once,
without reactivation. Once the package containing
the little pouches of anhydrous silica are opened,
and you throw these pouches in a drawer to save
them, they quickly saturate with moisture and soon
are rendered 100% ineffective.
For this reason, silica gel is almost always
limited to use in hermetically sealed packages;
you will seldom see it used elswhere.
OTOH:
Calcium chloride, available at most hardware
stores, is better for a non-sealed environment,
because you can tell when it's exhausted - the
crystals will dissolve in their own moisture,
leaving nothing but a solution in the container!
The CaCl can be re-used by boiling the water away
on a stove (it will NEVER evaporate at room
temperature!). It is cheap, too - about $3 or $4 a
pound at the most. It is used to keep mildew out
of closets.
2) Air stagnation. Trapped air harbors moisture.
Fungi can't live without moisture, so simply
keeping the air moving may keep things dry enough
to retard their growth. I would still use a
dessicant, though.
And keep your lenses =out= of the camera bag, it
just stagnates the air and traps moisture within.
Leave them on a shelf, with caps loosely in place,
if at all. Dust is easy to deal with.
--
If the wall safe is very large, a cheap $200 room
dehumidifier may be the way to go , because it
will:
a) heat the air
b) dry the air
c) circulate the air in it's vicinity.
--
Mildew is a fungus.
It is a myth that fungi need total darkness to
thrive. True, the ultraviolet rays from the sun
are detrimental to them, but they seem to thrive
in open shade, even under artificial lighting.
Most mushrooms are grown in the dark, simply
because they don't really =need= light.
A light bulb may work for another reason; It
provides enough heat to keep the relative humidity
below 100%, which is what we really need, anyway.
Get some calcium chloride, and don't forget to put
it an open container that holds water (or you'll
have a mess)!
:-)
P.S.:
Oh, yeah, i forgot to mention that silica gel can be reactivatated in
a 300 degree-F oven overnight, but it's hard to tell when it is spent.
I opt for Calcium Chloride or Lithium Bromide, whichever is available.
--
-John S. Bond kingsnake WA6FRN/6
kingsnake photography; a division of Gyro Gearloose Productions
http://www.humboldt1.com/~gyrgrls/
Date: Tue, 17 Feb 1998
From: David Seifert dseifert@earthlink.net
Reply to: rollei@mejac.palo-alto.ca.us
Mark,
The statement that glass is liquid is largely true! With the exception of
many types of crystal which have metals (like lead) added normal glass is,
in fact, liquid. I am sure some types of optical glass are classified as
liquid.
It is extremely viscous so it flows at a rate which is not readily observed
but it does flow, nonetheless. This phenomenon can be seen quite clearly in
the ancient cathedrals in Europe, where there are stained glass windows
which are 400-500 years old, St. Chapelle in Paris is a good example. The
glass has flowed over the centuries and is very thin at the top and very
thick at the bottom. When the glass was installed it was of uniform
thickness.
Best Regards,
David Seifert
-----
[Ed. note: But...]
Date: Tue, 17 Feb 1998
This was recently discussed at huge length on the Questar List. It turns
out that glass does NOT flow with the years as many believe. There is
supposedly a write-up proving this on the Urban Myths web site.
Marc
-----snip, snip, snip------
Parker also, in his ''User's Guide'' I think, puts forth the following
absurdly amusing proposal to explain why some 2.8 A tessars had some
problems:
Sorry, this is a paraphrase from memory, not a quote.
He says, Glass is a liquid. During the long time these lenses were ''in
storage'', they may have absorbed some moisture, changing their optical
properties.
This may not quite as absurd as it sounds, although It certainly does not
explains the bad Tessars.
Some optical glass is not very stable and will absorb moisture. These
glass types are not used in common lenses and when they are used are
cememted between more stable glasses. Some of the first glasses developed
by Shott were so unstable that they could not be used despite having
desirable optical qualities.
The effect is a rather rapid corrosion of the surfaces or discoloration
of the glass.
Classical Tessars are made from Dense Barium Crown and Telescope Flint
glasses which are quite stable.
Humans seem not to like mysteries so people will often make up answers
where an actual answer is not known.
Its too bad when such speculation is presented as fact in a book.
In general about Tessar type lenses. Like any lens the corrections can
be made more easily with a slow lens than a fast one. The critical thing
being the curvature of the surfaces involved. Tessars are at their best at
fairly slow speeds. The current large-format Nikon f/9 Tessars being an
example. At f/2.8 the design is really right at its limit. Some good
f/2.8 Tessars have been made, especially with post-war glass types, but
most of them are inferior to slower versions.
It should also be noted that some aberrations scale with focal length, so
that its harder to make a lens of a given speed for longer FL's than
shorter. On a 35mm camera a lens may be satisfactory at f/2.8 that for
Rolleiflex format isn't.
I have never seen any critical comment on the f/2.8 lenses used on the
Zeiss Ikoflex III. It has been stated on this list (By Marc, I think) that
this is the same lens as the CZJ one used for the Rollei. This model of the
Ikoflex was made for only a short time and its a collector's item now.
Has anyone here got one and if so how does it perform?
----
In large format photography forums it is
commonly mentioned that Angulon lenses shift their focus as they
are stopped down.
Focus-shift is a real phenomenon. The actual point of focus doesn't
change but the percieved point of best focus does. That is because most
people judge focus on a ground glass by maximum contrast.
The cause of focus shift is uncorrected zonal spherical aberration. Some
types of lenses have a particular problem with this, the Dagor, and related
designs like the Angulon, being among them. If the surface of the lens is
divided into imaginary rings and the point of focus tested it will be found
that the focus for the zone about the sqrt2 from the axis has the maximum
deviation in most designs. The greatest deviation is placed here because
the over all compormise is best this way. When a Dagor or Angulon is wide
open the image appears to be slightly hazy. The haziness becomes minimum
at some focus setting. When the lens is stopped down this haziness
dissapears, due to the reduction in spherical aberration from the outer
parts of the lens, and the point of best focus seems to move toward the
lens by a little.
Some people judge the point of best focus differently and do not observe
the shift.
----
....
The Mamiya 6 did come with a white paper in which the 75mm was described
as an orthometer (if memory serves). It was described, by Mamiya, as not
reaching an optimum performance until 1.5-2 stops down, primarily because
of undercorrected spherical abberation and field flatness wide open, to
achieve near perfect distortion correction (again from memory. If I run
across the paper, I'll quote the passage).
Couple this with Luigi's expectation that the lens should compete well
with the Planar's of the R'flex and H'blad and, it seems to me, that we
have a case of compromised expectations. When you lose confidence in your
camera, it's very easy to see the results as inferior across the board,
even when they're not truly inferior in every case.
Mamiya definitely 'fixed' the 80 on the 7 and in comparison to the 6 75mm,
the 7's 80is just much better wide open. Whatever Mamiya's reasoning for
making the 6's 75 the way they did, they did realise the error of their
ways.
The other 6 lenses, the 50 and 150, perform far better than the 6's 75
does full open and there's not a lot else to be said about it.
Danny Gonzalez
From: "Tom Clark" tomclark@sprynet.com
I agree that when comparing lenses from the top manufacturers, the
differences are negligible. I started a firestorm of controversy here a
couple of weeks ago when I did a semi scientific comparison between my 20
year old RB67 with a non coated lens and a 5 year old Hasselblad with a T*
lens. The Mamiya actually came out slightly sharper with no observable
difference in color saturation. When all is said and done, I think the
slight difference in sharpness might have been due to camera vibration.
Assuming we are talking about the top quality brands only, I would pick a
camera on the basis of features and price. If brand A has more features
and I can buy 3 lenses for the price of 2 brand B, I'll go with brand A
every time.
Tom Clark
Date: Mon, 23 Feb 1998
I slipped yesterday and smashed my 'Blad heavily into a rock, lens down...
Fortunately the plastic hood took all the impact and cracked into pieces.
Not a single scratch on the lens. Now I know what all that talk about
''deformation zone'' in cars is all about!
Hekan Gunnarsson
Date: Thu, 26 Feb 1998
Guys, if you know anything about photography, its real hard to fake a
multicoated lens. Look at the glass at a slight angle, you should see a
rainbow of colors from the multicoating. You can't fake that!
Lance
Only those folks who have NEVER seen a T* multicoated lens. The
Hasselblad/Ziess coating the puit one the older C lenses looked purple when
light was refelected off at a slight angle. By contrast the newer multi
coatings, T*, have a green cast to them when light is reflected off at a
slight angle. It is easy to see the differences when you see one of each to
learn how to compare. To my knowledge, Hasselblad only put multi coating on
a few lenses that were NOT marked as T*.
Joe
multicoated lens. Look at the glass at a slight angle, you should see a
rainbow of colors from the multicoating. You can't fake that!
Granted, but the deception occurs when the coatings *aren't* of the T*
type...
Joe McCary
[Ed. note: Fred makes some excellent points re: lens testing (he runs a
great nikon lens test site online) and the importance of subjective
factors below:]
rec.photo.equipment.medium-format
The problem is that lens testing is subjective to a large extent. There
are many tradeoffs in lens design. Improving one characteristic can make
another one worse. In terms of resolution and distortion, most high
quality lenses are very similar, at least at infinity focus. The Germans
have a tendency to give up some contrast in favor of sharper corners at
large apertures. The Japanese tend to give up some corner sharpness in
favor of contrast. Obviously this doesn't hold true throughout any
particular lens line, it's just a tendency I've noticed over the years. It
becomes a matter of taste. It's easy to publish numbers on resolution,
distortion, aberrations etc. but most of the good lenses would have similar
(excellent) numbers. It's the subjective parts that cause the bar room
brawls. I've used the mamiya 6, by the way and was very impressed with the
image quality. I assume the lenses are at least similar to those of the 7.
Good shooting.
rec.photo.equipment.medium-format
I think I agree. Another way to look at it is to consider a camera lens as
a projector in reverse. If the field of view is projected 2" and yields say
150 lpm, then at 4" there will be only 75 lpm and so on. The quality of the
lens hasn't changed, only the projection distance. This is a gross
oversimplification of course since it ignores all consideration of real
world lens construction but it illustrates the point that the real quality
of the lens is in how the photographer uses it.
Glenn Kinsley: gkinsley at cybernet1 dot com (U fix it)
Zane zanekurz@ix.netcom.com wrote in article
Danny G's original question still has not been answered, which is why are
35mm lenses found to almost always have higher maximum lines per
millimeter
snip beaucoup
In summary, since a 35mm lens can be 1/2 the focal length, it can in
principle be made to have twice the resolving power in lp's/mm
(discounting
diffraction) if one is also willing to hold tolerances that are twice as
good. In practice, the cost of doing this is prohibitive and the results
using the same tolerances are a little better than the 6x7 in lp's/mm,
but
not twice as good. Also, people usually demand faster f/no's for their
35mm lenses. The major aberrations are usually proportional to the f/no
or it's square. To counteract this, more elements are used and the
effect
of tolerances is made worse.
This analogy holds also for comparing MF and LF by the same logic.
Whew! Still here?
ane
Nikon Digest - 3/3/98:
Call it superstition, but during extended stays in the tropics, I
regularly treat my lenses to a little sunbath. Once a week or so, I prop
the lenses up so that the sun can stream straight down through the lens
barrel. (Just watch what you put under the lens! Once I forgot to take
the back cap off my 80-200. The cap now looks like it's been sliced open
by a light saber.)
Perhaps it's the UV, perhaps it's the heat, perhaps it really is that
''Intensive Care'' Peli box stuffed with silica gel. Anyway, I've yet to
find a single mycelium in those lenses, despite multimonth stays in the
Borneo rainforest.
Djuna Ivereigh
Date: Sun, 01 Mar 1998
Fungus grows on lenses after a while when the lenses are kept in a moist
dark environment. This happens very rapidly, for example, on tropical
islands, if the lenses are stored away from the sun and not in an air
conditioned room.
The fungus will grow on internal elements or on external elements when
the lenses are coated. The coatings are what the fungus "eats" and so
even after removing the fungus the coatings are damaged and so while you
might get another period of use out of the lens before it begins to grow
back, the lenses are ultimately impaired by this growth and soon lose
all the coatings.
My experience has been that mild fungus growth doesnt much impair the
image quality, but I have seen lenses with a virtual fog of fungus that
cannot be focused at all.
The fungus starts off looking like a small spider like growth, usually
in only one or two spots, which then grows over time to larger and more
noticable colonies. If you open the apurture iris and look through the
lens (off camera) you can see the growths.
Prevention is the best and only treatment. If you live near the coast,
or in tropical environments, store the equipment in sealed containers..
I use pelican cases which are water tight. Additionally you should
include in the containers a descicant (Moisture eaters ) so as to keep
the gear dry. A dark closet, basement or garage is the worst place, and
Leather cases increase the odds of fungus growth.
I know a fellow who lives on a Caribbean Island who says that he gets
5-6 years out of his most used lenses before they start to grow fungus.
He uses them all the time, so he can't store them, as such. After this
growth the lenses are not in a condition to be repaired, so he simply
buys another one.
Where I live (Narragansett Rhode Island on the ocean) this can take
considerably longer, especially if you use air conditioning in the
Summer, but growth on lenses is very common around here, and begins
early or late depending on how the gear is kept... To date, I have had a
tiny bit of growth on a single Mirror lens, and since that happened have
been storing my gear more carefully.
Hope this helps.
- --
SilverLight Studios, Inc.
mailto:psilver@silver-light.com
From: John Yu jyu@objectmastery.com
1. What does the fungas use for food? What does it grow on?
Fungus feed themselves on the lens coating.
2. What does the fungas look like? How would one know if there was
fungas on a lens?
Take a look at this site:
http://www.chem.helsinki.fi/~toomas/photo/fungus/. Toomas Tamm has photos
of fungus over lenses.
3. How is the fungas treated and/or removed?
The above site has info on this regard.
- --
Date: Mon, 02 Mar 1998
To answer your questions:
1. It needs moisture from the air, it needs EXTREMELY LITTLE ! (I had
fungus on my lens here in Kalifornia!), it can grow on anything you can
imagine...including chromed surfaces.
2. On my lens it look like fog! on the coating of the front element, or in
other words, the coating lost its gloss, it look matte without any color.
You know its fungus when you try to clean it, it wont go away with
anything!
3. You can slow or stop its growth with ammonia or chlorine, but it won't
clean it's damage on the lens. But the good news is that you can remove
it: by replacing the element which was attacked by it. :-( I had this
experience with my 15mm/3.5 Nikkor...(expensive) You can prevent its
growth by exposing your lenses to direct sunlight! The UV rays kills the
fungus! Advice: don't keep your lenses in dark nonventilated
areas for too long.
Date: Mon, 02 Mar 1998
One thought I have had during this discussion about fungus on
lenses is that it would probably be helpful to _kill_ any
fungus growth before it gets out of hand. To this end, my
guess is that a high dose of x-rays or uv radiation (similar
to what's used to sterilize food by irradiation) would probably
do the trick.
Now, high doses of x-rays are going to be hard to come by, but
UV isn't too rare. A good solid 'tropical' plant light, left
shining into the lens for a few days, would probably kill off
anything growing in the lens. It's also possible that a few
minutes (like maybe 10 minutes) of sitting in an airport x-ray
machine would be enough.
Would anyone with a 'funged' lens like to try it?
Cheers,
- --
Date: Sat, 7 Mar 1998
Recently, I observed some dust particles on the internal elements of my
Nikon AF-D 28-70 f/3.5-4.5. Of course, this is really nothing compared to
having fungi or scratches on the lenses, but I'm a bit worried about its
effect on the len's overall performance. I was thinking of having it
cleaned, but it would mean having the lens opened up, and I'm not sure if
it's worth the risk. There have been reports of lens misalignments after
repairs or cleanings are made.
Dust on elements is very unlikely to affect picture quality, and
what's more, with any zoom that changes its length (and therefore
sucks in air all the time), dust on the elements is inevitable
(apart from pro-quality lenses which have felt baffles to keep it
out).
- --
Date: Fri, 06 Mar 1998
If the images are crisp and sharp then there is no need to overhaul the
lens. I have an elderly 80-200mm zoom Nikkor from the mid 70's. A year or
so after I bought it I noticed that a tiny fruit fly had died on one of the
zoom elements. He's still there some 20 years later and my slides are
still coming out just fine without any evidence of his tiny little body.
On one of my enlarging lenses, the lubricant from the aperture had
gradually deposited onto to the adjacent elements. That lens *required*
cleaning since lens was not working properly anymore.
In assembling a zoom lens, the factory has custom test and alignment
fixtures that are used to make sure that all the required tolerances are
met. Your local repair facility will not have this specialized equipment or
the expertise that the factory has. You don't want to have someone operate
on a zoom lens unless it is necessary; it just may not come back as good as
it was before the service.
Make lots of images with your dusty Nikon zoom and share and enjoy them,
that's what I'm doing.
Robert Hudyma, Semi-Tech Corporation, 131 McNabb Street,
From: nycfoto@aol.com (NYCFoto)
There is one big problem in shooting a resolution chart, and that is that
the chart is usually fairly small and fairly close to the camera/lens.
This is fine with macro or APO lenses which may be optimised for large
reproduction ratios, but most 35 or MF lenses are optimised for about 1:20
scale, so if you use a res chart with them you are not testing them at
their best repro ratio.
Regarding optimised f stops, Rodenstock does optimise at F22, although
some of the APO lenses may be better at 32. Hasselblad optimises at 11,
and most 35mm format lenses are optimised at around f 8.
From: dannyg1 dannyg1@idt.net
For many years, there has been common lore that lens quality is directly
tied to coverage and format size. I've done cursory testng to disprove the
notion but don't have enough absolute data to refute it as pure myth.
To be sure we're all understanding the point, it's preached from
mountantops everywhere that lenses for 35mm are better than medium format
lenses, which are better than large format lenses. For the purposes of
this discussion, 'Lens quality' should be defined by lpm transfer,
contrast transfer and distortion control.
If we excise the extremes (anything above 4x5 or below full frame 35mm),
is the myth definitively correct, or as I suspect, a massive
generalization that could never be truly correct?
Thanks,
From: John Munro jlmunro@texas.net
The Mamiya 50mm non-"C" lens is indeed a single-coated lens. My business
has this lens and its "C" multi-coated counterpart. Both exhibit
identical flare tendencies which are quite reasonable. The only
significant difference I have been able to measure between these lenses is
that the "C" lens transmit more light and is an effective 1/3 f/stop
faster. Hope this helps.
Date: Mon, 06 Apr 1998
The recent thread on cleaning lenses has been interesting and
informative. It took me a while to recover from some bad advice I got
early in my career. Someone told me that dirt and fingerprints only slow
down the lens a bit. I had to discover on my own that a fingerprint
smudge on the rear element of a wide angle could cause significant loss
of resolving power.
Myself, I won't use a lens that has significant scratches or chip marks.
However, I have been told that a chip in the front coating may cause
flare, and that touching up the chip with some "India Ink" may eliminate
some of the flare.
Does anyone have an opinion as to what level of scratches and chips
can be tolerated on front and rear on various lenses, beyond what I
have expressed here?
Peter
Date: Mon, 6 Apr 1998
Hi group,
I recently purchased a 150mm C T* with a big "nick" on the front element.
The price was very low because of this defect. Because I use a lens hood, I
haven't been able to see any real problems, at least not from flare. I wish
it wan't there, but I saved about $600-700, becuase of it. I have yet to do
a 20x24 enlargement to see if I can spot a soft area.
Bob Keene
from Nikon Digest
lawrence
the dot that u were referring to could be one of two things. assuming that
u have already eliminated the possibility of dust/dirt particles, they
might be:
1) water spots. occassionally, when you are speaking to someone while
the lens is pointed at them, or speaking to the sales person over the
counter with the lens straight up (as is the norm when buying the lens),
tiny bits of saliva could have landed on the lens and caused the dots when
they dried. Or it might have been from when you blew on the element to
clean off a bit of dust.
no worries... just use cleaning fluid and lens tissue to wipe em
off. Or a lens pen. i personally prefer a lens pen, easier and less messy.
but make sure you blow the element and dust it first, don't go dragging any
particles of grit all over the element.
2) the worse scenario would be fungus spores. there is nothing you can
do abt it, short of sending it in for cleaning... and it has been said that
the quality will never be the same again. this is unnecessary until u see
tendrils of fungus spreading over the glass, as spores will not affect the
quality of the picture and will cost a bit. seriously, a bit of fungus on
your lens will not very noticeably affect your pictures.
how to tell if they are spores? first treat them as tho they were
dried drops of water and clean as above. get it clean and keep the
aperture wide open at 2.8. then holding the element to your mouth... breath
on it to fog the element. quickly look through the rear element while aimin
the lens at a light source (like a bulb, DO NOT USE THE SUN). a fungus
spore will show up as tiny white speck with a halo of clear glass around
it. dust won't. if the fogging clears, do it again. u can reverse the
arrangement to check the rear element.
but before u panic, if u r in the US, most of the country is fairly dry and
it's not likely to be fungus on your lens... but if it is... well.. u gotta
live with it.. and check all your other lenses and invest in a
dehumidifying cabinet.
Martin Lim
From: "A. Bontenbal" bontenbal@ecn.nl
There are lenses that used optical glass with thorium in it. Thorium gives
soft gamma irradiation that stops in a few centimtre air. The irradiation
level is zero, otherwise your film would go black.
E-Mail : bontenbal@ecn.nl - A. Bontenbal
Date: Sat, 11 Apr 1998
Theoretically, one less lens element could improve image quality as
many of the additional lens elements are just there to correct
distortions caused by the primary elements. So if you can just
reduce the previous distortion, the need for additional elements
(which necessarily introduce distortions and loss of contrast of
their own) deminishes. Take a look at "exotic" designs of the last 20
years, particularly zoom ones. They are smaller, lighter, have fewer
elements but with the improvements in computer design the quality has
gone up.
Hopefully, this is what Zeiss is doing, not just cost-cutting.
Simon.
From: "skgrimes" skgrimes@ma.ultranet.com
Minor blemishes on the surface of a lens cause no noticeable difference to
the image because the defect is too close to the surface of the lens to be
resolved. You can prove this by holding something large across the lens,
such as a pencil and observe that the image produced is virtually unchanged.
You can get some real bargains on blemished lenses because (with the
exception of some extreme wide angle lenses) the blemishes reduce the price,
not the performance.)
---- S.K. Grimes -- Feinmechanik ----
From: "David Foy" nomail@this_address.please
A book I have on lens and shutters from the '40s says much the same thing,
and suggests filling a scratch on the front surface with black ink or paint
to eliminate any flare it might cause (it also says a cracked front element
that hasn't dislocated will cause zero image problems!).
But I wonder -- is the same true of marks on the rear element? Would that
create a noticable diffraction?
From: Mark Bergman mb50742@navix.net
Marks on the rear element will make a difference.
From: kirkfry@msn.com
Depends, one or two or three small scratches will make virtually no
difference other than reduce the price of the lens. "Cleaning Marks" can be
mean the same thing as fixer upper in the realestate market; like someone
sand papered the lens surface. Obviously this will drastically effect
results, on the other hand it can be a slight smudge on the coating that will
have little effect. You basically have to look for yourself and decide.
Fogged lens surfaces on the inside can sometimes be cleaned, if not this is
bad. Bad separations between the elements are bad.
From: steven T koontz skoontz@mindspring.com
well I used to be real picky about the glass I use until I tried a
minolta autocord that the front element looked like an ice skating
rink.. The guy said I could try it and return if it didn't work good
but he assured me I would be happy.. he was right. I now have another
autocord with perfect glass and can see no difference in the two. I
alway shade the lens and never do backlite shots so maybe this is
why.. Now I tried a old Ikonta with a smudged up lens (some fungus I
assume) and it was awful. I now hold a lens away from me and focus
looking through it. If it looks clear with no halo's or smudges I go
with it..
steve's photography & Z car stuff
Date: Sat, 11 Apr 1998
I recall a posting to a reent digest asking to see samples of bad bokeh
- - Well, rather than trying to e-mail samples of some photos that show it
let me refer those who have access to Popular Photography to the
"Nature" article in the Aprin '98 issue.
The photo of the leopard on p. 40 is a prime example of bad bakeh - the
out-of-focus background highlights, instead of turning into soft blurs
appear as distracting circles.
The photo of the bobcat on p. 39 shows the same problem, though less
severely - in part perhaps because the lens might have less bokeh
problem, but the imporvement is almost certainly attributable in part to
the fact that the background is more totally out of focus.
The grass behind the chimp on p. 38 shows some evidnece of the same
problem - though you'd probably have to see the orginal print to be sure
what's gong on.
All these pictures were taken with Canon lenses, but I see the same
problem with my Nikkor AF 80-200/2.8 D ED (one touch) - which is one of
the reasons I do more and more of my tele work with my 105/2.0 DC and
TC16A - since the 105/12.0 produces a very smooth, pleasant bokeh.
(And by the way, does anyone believe that the photo Sigma uses in its
70-200/2.8 ad on p.23 was actually shot at f/2.8, as the caption
indicates? It's sure my Nikkor 80-200 couldn't get that shot . . . have
Sigma engineers have discovered a secret way to extend dof at large
apertures? I'm sure no one would suspect that the lens was actually
stopped down in order to achieve that corner-to-corner sharpness . . .
or would they? Well, let's see - judging by the shadows, it was shot in
mid-day sunny-16 light - so, if it was shot at 1/250th and f/2.8 - then
the film speed was around ASA 15 - or maybe Yamshita used Velvia at 40
with a polarizer to eliminate the reflections that weren't eliminated .
. . or maybe there's something wrong with the data? But we know no lens
manufacturer, especially a reputable company like Sigma, would ever
publish misleading data!)
Bill Boyle
From: dickburk@ix.netcom.com (Richard Knoppow)
Well, I think you are lucky. I have compared some 127mm Ektars with
and without _serious_ scratches and the difference in contrast is
striking. The scratched lenses were the kind that look like they have
been cleaned with sandpaper. The scratches act like a fine diffuser
over the front.
Scratching on the rear element is worse.
A few scratches or a gouge will not affect performance much but
seriously scratched lenses, IMHO, should be avoided.
---
rec.photo.equipment.large-format
That white triangle puzzles me, I've never seen one on a Schneider
lens. The red triangle is the mark for coated lenses but all the
uncoated Schneiders I've seen had no markings on them. So I wonder
what that white mark is all about.
I've had a chance to compare only a couple of lenses with and
without coating where I know the actual lens design is the same. One
was a Kodak Ektar, 127mm f/4.7, as widely used on Speed Graphics. One
lens is a 1941 uncoated version, the other a 1946 single coated
version. The contrast is very similar. The older lens had very poor
contast at first due to a coating of haze inside. Removing the haze
increased the contrast very noticeably. Coating certainly increases
the contrast of lenses so your observations are accurate. But I am
wondering if there isn't something else contributing to the poor
performance of the uncoated lens. Perhaps not.
---
rec.photo.equipment.medium-format
Interesting experience. One wonders how so many excellent pictures were
made without coated lenses, back in the "old" days. I've heard it said
that some of the older uncoated lenses developed a "bloom", apparently
some kind of oxidation coating, over time. It's said that this is what
originally inspired the idea of coating lenses. Don't know if it's fact
or myth, but some of the old pictures seem to be great. Maybe one
shouln't go around cleaning the surfaces of one's uncoated lenses? I
have a 135mm Meyer uncoated anastigmat that delivers excellent results
with my Crown Graphic, and I clean it occasionally.
Bill Martin
Date: Sat, 25 Apr 1998
IF the only damage is to the front _coating_ i.e. no abrasion of the
glass that could result in diffusion, its going to affect the performance
of the lens very little. 100L sounds like an awful lot to fix what might
be a really minor problem. The coating on the other lens surfaces is
likely unaffected. It is sometimes worth opening a lens to clean it but
that should be very much less money. Check the surfaces with the aid of a
loupe and a flashlight (are they still called torches in the UK?), that
should show whether the pollish is still OK.
----
Having already responded to this thread this message gave me another
thought. It may well be that the coating is OK but has been overlayed with
an oily coating or, perhaps, been cleaned with one of those silicone
impregnated tissues for cleaning spectical lenses (don't use them on coated
glasses either!). A solvent like Acetone will take it off. Acetone is a
standard solvent for cleaning optical parts. Apply it sparingly with a
lintless tissue like a "Kimwipe". This isn't needed for routine cleaning
but may be needed where there is something oily or waxy on the lens surface.
----
Hmmm... Acetone? Your theory seems viable but might that not be a bit
too strong? My service person recently sold me a product called ROR'
(Residual Oil Remover). "Designed Specifically for All Photographic
Lenses". Said it was developed for NASA and used for cleaning optical
surfaces. I know it has worked very well for me and he swears by it.
One ounce bottle distributed by V-VAX in Chicago. #312/276-1747.
hth,
Scott Gardner
Date: Sat, 25 Apr 1998
Acetone has been a standard solvent for cleaning optical parts for many
years. It won't damage glass of modern coatings but must be used with care
since it will dissolve some optical cements, especially Canada Balsam, and
will also attack some types of paint. It is a very good solvent for oils
and waxes. I don't know what is in ROR, the usual lens cleaner is a
solution of Ammonium Carbonate. Windex etc, is Ammonium Hydroxide. The
Hydroxide may be safe most of the time but some types of optical glass
are sensitive to very alkaline substances so the carbonate is safer.
This is what Kodak lens cleaner is.
ROR may have an MSDS on Hazard.com. I will look for it later. In any
case it can't hurt to try it, it's likly some sort of detergent.
----
Date: Sat, 25 Apr 1998
It can be recoated, but it may not yield any better results.
If it works, why fix it? Better to leave well enough alone.
I have seen many 2.8s that seem to lose the coating from wear, use, or
whatever. Not uncommon, exspecially on the Planars as opposed to the
Xenotars.
Both will scratch easily but I it seems that the coating on the Zeiss
lenses are not as durable as the Schneider.
Peter K
Date: Sun, 26 Apr 1998
The coating on the 2.8 Planar seems to be very soft and perhaps with age
and due to oxidation, gotten even softer. But remember that it is only one
element in your lens that has lost a bit of its coating. All other elements
are coated and probably still have their coating as they are not subject to
the same wear that the front element is exposed to. The purpose of coating
is to increase the amount of light transmitted through a lens (resulting in
higher contrast images) as well as to correct for colour casts if needed.
If the front element were to lose all of its coating, I'm sure that there
wouldn't be a huge difference in the resulting film, in fact one may have
to look very hard to see any difference at allas there are still many
surfaces in a Planar that are coated.
I suspect that Chris, who mentioned that his lens was "cleaned", actually
has had the coating removed from the front of his lens and that the results
that he gets is not different than before he had his lens "cleaned".
...
rec.photo.equipment.medium-format
Each air to uncoated glass surface reflects about 4% when the light is
perpendicular to the surface, ie. light going straight into the lens. The
percentage is higher for light striking at an angle. So the light from the
subject itself can cause excessive flare in an uncoated lens. Those
folders probably have four element lenses with maybe 6 air-glass surfaces
and one glass-cement-glass surface, so total reflections are about
(6*4+1)=25%. That's 1/2 stop of light loss. Some percentage of that ends
up as flare.
Coated and multicoated glass reflects much less light when it strikes
perpendicular to the surface but the coating is less effective for light
at an angle. For this reason a lens hood is a good idea even with a
multicoated lens to block light striking at a steep angle.
Look at a multicoated filter with a flashlight in a dim room. With your
viewing angle and the light nearly perpendicular to the surface the
reflection will be dim with the characteristic color of the coating. If
you hold the filter at a steep angle an align the light behind the filter
the reflection will be stronger and whiter.
TB
From: steven T koontz skoontz@mindspring.com
Well I've heard several peoples opinions on this and though I'd pass
this story along.
I just bought two old 6X9 folders with (what I thought was) the same
lens, a schneider radionar 105 4.5 that were both in almost "like new"
condition. Now admittedly this isn't the best lens schneider ever made
but is is OK for casual shooting.. Well after cleaning and lubing both
shutters, cleaning up the glass (which looked great on both cameras),
checking focus scale and infinity focus (with ground glass on the film
plane), and checking for pin holes ect, I loaded them up with T-max
400 and went out testing.. I shot with both cameras on a tripod at the
same locations using the same coated B&W; yellow filter for each shot,
with the sun to my back for each frame (no sunlight hitting lens)...
Well when I got home, I developed the film (3 rolls in each camera)
and was disappointed that one was noticeably contrastier and appeared
"sharper/snapier" than the other. When printing, it was obvious which
camera was better. Also I had hoped that the "bad" one would be the
better of the two as it had a smoother shutter release mechanism but
it wasn't even close.. Well a couple of days later I was looking at
them outside on the porch trying to figure this out and noticed (by
the purple sunlight reflection on the lens) that one was coated and
one wasn't. Then I saw one had a red triangle (the coated one) and the
other a white triangle so I now knew they were different.. You can
guess which one was the bad one (obviously the uncoated one).
My point of this story is: I had just tested coated vs non coated
without knowing it and found it obviously inferior to use an uncoated
lens even with no light striking the front element.. contrast was
noticeably lower and neg apparent sharpness was less. While they were
equally "sharp in focus" the uncoated one appeared less so due to
lower contrast. I had also had problems with the one other uncoated
lens but people had told me "It doesn't make that much difference on
simple lenses like those camera's have". Some of these people were
folks whose opinions I value so I thought "Maybe it's something else."
I now beg to differ.. Twice I have had this same low contrast problem
and both times they were uncoated lenses. Maybe these people don't
have problems with them but I will never fool with another uncoated
lens.. Too much quality lost for me.
--
Date: Tue, 28 Apr 1998
The color is due to the thickness of the coating. Single coatings
prevent reflection at a single wavelength. The residual color is what
light is reflected. Blue coatings are peaked in the green region. Usually
the color is actually magenta. Amber coatings are peaked more toward the
blue so the reflection is minus blue. Multiple coatings are used to broaden
out the range of colors for which the coating is effective. Multiple
coatings sometimes have a green color since they have double peaks at the
ends of the spectrum. A _truely_ wide band coating would have a neutral
gray reflection if any.
The theory of lens coatings is closely related to filter and transmission
line theory in electronics.
----
Date: Mon, 27 Apr 1998
Last year I had my 15mm fixed by Nikon service in Torrance. It took them
6 mos. instead 3-4 as promised. Problem was fungus on front element.
The lens has to be shipped to the factory in Japan. Cost $199, which I think
is standard for any repair regarding optics.
You decide if it's worth the trouble.
From: Keith Nichols knichols@lightbridge.com
Well, I wanted to respond after getting a few test rolls through the Ikonta.
After using my Rapid-Omega for a few months and now the Super Ikonta, I must
say that I'm slightly stunned. Going from mediocre 35mm to medium format and
these lenses is amazing. I'll admit that I'm now covetous of flash sync
on the
6x9, which I may look around for, but I doubt that I would give up the Tessar
lens for anything less than comparable. Of course my first non-test roll
WOULD
be shooting a 2 year-old in the park, but at least I learned to shoot on
an SRT
201. The only thing new is cocking the shutter.
A few people responded by email, which I appreciate, but I would encourage
everyone to post responses when appropriate. For instance, I learned
that the
stiffness at 1/400 is due to an added spring. Also, even given my limited
experience so far with the uncoated Tessar, I would say that the warnings
I've
read about color correction and contrast are misplaced. Robert Monaghan
addresses these at http://www.smu.edu/~rmonagha/bronfaults.html, Non Problems
and Myths. The color and contrast on my chromes are quite good. I also shot
the roll of the 2 year-old on a walkway out in shallow water on a bright,
sunny
day and had no flare problem.
Thanks again for all your help.
rec.photo.equipment.large-format
First, you should try the lens as is -- there's every reason to expect it
to perform well. Aging balsam with a yellowish cast is common as an "in
service" condition. It the lens delivers acceptable results leave it alone.
There is an entertaining article (internal link "re-cementing") re-printed
from a 1944 Popular Science about how to re-cement discolored lenses on my
website: SKG
see: http://www.skgrimes.com...
rec.photo.equipment.misc
I'm hardly an expert, but I do mechanical design on P&S; cameras and so
am somewhat familiar with the topic. Anyhow, all our better P and S cameras
use glass lenses. They are more expensive and harder to make in
aspherical shapes (verse plastic molds). One advantage is that glass
lenses distort less with temperature change than plastic lenses. (There
may be others reasons, but that was the big factor on the last project I
was on.) However, glass is heavier which might be why manufacturers are
using plastic. (And then they use software control to adjust focus for
temperature. I know we have cameras that do this.)
From: "David Foy" nomail@this_address.please
Fungus spreads in the adhesive layers that bind multi-element groups, which
is what nourishes it. Getting rid of it involves separating the elements,
cleaning off the old adhesive, and re-cementing. It's almost always
uneconomical, and if the fungus has etched the glass, which is usually the
case, the etched elements have to be replaced.
What is often called "fungus" on glass surfaces is really cloudiness from
atmospheric deposits. Ed Romney's cure for this haze has always worked for
me -- 50/50 household ammonia/drugstore hydrogen peroxide, swabbed on,
allowed to do its work (you'll sometimes see foaming) and rinsed off with
water (remove the lens from the camera or shutter first).
[Ed. note: the following for sale posting was interesting as it cites
bubbles in some nikon lenses, dust, and related lens ''faults''...]
From: clemsontom@aol.com (ClemsonTom)
55mm Micro Nikkor , f2.8, Mint-, few specks of dust on internal surface, and
one glass bubble (In the 50's and 60's there were great debates relative to
bubbles vs. no bubbles. Nikon's advertising, at that time, boasted "no
bubbles". Of course, bubbles have no influence, as was then proven. Things
don't
change very much.) Exterior of lens appears mint. Price:$190.00; 80-200mm
Zoom
Nikkor,f4.5. I sold my f4.0 Zoom Nikkor when I compared the two(tripod
mtd, of
course). I have two, and am keeping one. Price:$175.00. Add shipping and
insurance.
Date: Fri, 29 May 1998
"Marc Van de Craen"asked about
>Subject: distortion of 35-70/f2.8 Nikkor lenses. Marc said:"
>I tested the lens by taking pictures of the bricks in
>a wall and I noticed that particularly at 70mm the lines are quite severely
>curved at all sites in the viewer....
The finders of all Nikons except the F, F2, F3, F4 and probably the F5
have distortion built into them. I forget the reason why this is done.
However, it means that one cannot assess distortion by looking in the
viewfinder if the viewfinder contributes its own distortion. You mentioned
that your photos showed some distortion, too - To see the distortion, one
has to look at the photos - preferably the slides or negs.
I never had a problem with this viewfinder distortion until I tried
using an FM2 and an N90 on a copy stand. I couldn't get anything
straight, even with E screens. Then, I started doing my copy work with
an F2 and F3,
both of which have essentially distortion free finders that make it easy
for me to get my copy work perfectly straight.
-Mark Walberg
Date: Fri, 29 May 1998
Well, the lens dates from 1936, Zeiss's single most productive year, so the
camera probably dates from that year or, maybe, a year later. The lens
should not be coated.
So what? I have a Prewar Super Ikonta B I use regularly -- avoid shooting
unhooded into light, and you are okay. The lens works wonderfully, as
expected.
Date: Fri, 29 May 1998
Mark MacKenzie,
Some of my older cameras have a bloom on the front of the lens, which has a
rainbowish coated look to it. This is a natural oxidation of the glass and
is not a factory coating. I read somewhere that this is where the idea of
coating came from, as lenses with this bloom produced negatives that were
slightly sharper looking than the same lens without this bloom. I think
that a lens with bloom is in truth not sharper, but may have slightly
greater contrast, resulting in what some may consider a "sharper" picture.
Todd
Date: Sat, 30 May 1998
The bloom on older LF lenses is what caused the British researcher and
optical designer, Harold Dennis Taylor, to begin, in the 1890's, the
investigations which led through twisted paths to Alexander Smakula
developing hard coatings forty years later. (One of the intermediate
investigators, the man who actually figured out HOW this stuff works, was
Dr Karl Bauer, who went on to be in charge of Carl Zeiss USA from 1935
until 1960 -- I have spoken with a number of folks who knew him, and a gent
and a scholar he seems to have been. He would come out of his cubby to
help customers personally, and knew the Zeiss product line in great detail.)
The bloom causes a greater concentration of light rays -- that is, it
prevents scatter under contre-jour conditions. This leads to a picture
with greater contrast. The sharpness and other optical parameters remain
the same.
Marc
Date: Wed, 27 May 1998
I thought I might put in my two cents here, as I have had similar problems
befor- in fact what prompted to reply was the case of a Planar 80/2,8 from
an Hasselblad I got about twenty years ago from an estate sale. The lens had
these curious white marks, shiny like oil or water spots. I found out that
the lens had been in a drawer with some silverware. I can only surmise that
prolonged contact with the silver allowed some reaction with the coating
material. I used the lens for years with no problem or loss of sharpness.
Possibly these spots can occur from environmental elements- I have one on a
Rollei 2,8F and the photos from this camera are at time disgustingly sharp.
It shows every pore, hair, or blemish on an otherwise beautiful face. I now
know what Softars are for!
dwpost@msn.com
From: dickburk@ix.netcom.com (Richard Knoppow)
There is very little chance of separation in lenses built in the
last thirty years or so unless they have been subjected to extreme
mechanical shock.
Lenses built up to about 1947 were cemented with Canada Balsam, a
resin obtained from Douglas Fir sap. This cement has good optical
properties but does not do well with temperature extremes and tends to
crystalize after a long time. Old lenses cemented with Balsam often
show a yellow or brownish ring around the edge of the cemented
elements. This does little harm if it isn't large and progresses
slowly wiht time. More extreme separaton can be found as the result
of exposure of the lens to temperature extremes or mechanical shock.
This can result in a milky appearance or white feathery crystals, like
frost in the cement layer. Fine bubbles can also sometimes be seen,
probably the result of elastic stresses caused when the lens was
assembled.
Lenses made between the 1950's (but some as early as perhaps 1940)
are cemented with thermo-setting synthetic cements. This is more
stable than Balsam but can also separate. Particulary, mechanical
stresses in the glass which are not properly relieved can cause
eventual failure of this kind of cement. The stresses can be caused
by the relatively high curing temperatures which were needed.
Separation can be in the form of large bubbles in the cement or
sometimes whiteish rings. Sometimes the cement will develop an
"orange peel" texture and cause some diffusion. Shining a flashlight
through the lens will often show up faults like these.
For the last twenty or thirty years lenses have been cemented with
either low-temperature curing binary cements or with cements which are
cured by exposure to ultra violet light. Both are less likely to
cause thermal strains in the glass which will cause later failure.
There are also cements now which remain somewhat elastic after
curing. These are valuable when cementing lenses with deep curvatures
or where adjacent glass has a large difference in the coeffecient of
expansion.
I think the chances of finding a new lens from any reputable
manufacturer with any separtion is negligible. Again, slight edge
separation in older lenses has little effect on performance.
I am sure this is much more than you wanted to know:-)
---
From: "Christopher M. Perez" chrisper@vnd.tek.com
Have to admit that I have yet to see any of the new APO plasmats, wide
angle (>100 degrees), and aspheric lenses with any separation. But having
said that I have seen quite a large number of late '70's to mid-'80's
lenses what have the previously noted "air bubbles" at the edges of the
element groups. Primarily in the front group (with the largest elements).
Mostly noted at the photo swaps I've attended over the years. Of course
the Rodenstocks I've seen (from the early '60s to '70s) have been the
worst offenders by far... which is what I think the original point was...
:-)
None of this ever effected the performance of the previously described
Symmar-S/MC 210 I owned (any yes, the new owner is _well_ aware of my
neurosis concerning separation). The bubbles didn't appear to grow in
size once they were seen. AND, this lens was never abused (looked/worked
as good as the day I bought it as a demo from Schneider in '82).
Given your comments about the new cements I'm really tempted to buy a
small new tessar or ??? design 200mm+ lens for field work... so thank you.
- Chris
From: Kerry Thalmann K.Thalmann@worldnet.att.net
Hi Chris,
I believe the "air bubbles" you described are not actually element
separation, but they seem to be a defect between the edges of the glass
elements and the metal lens barrel they are mounted in. I've seen a ton
of old convertible Symmars and even a fair number of Symmar-S models
with this defect. I don't think this will have any effect on the
optical performance (if bad enough, I suppose in theory it might cause a
little flare) since the defect is not in the optical path. I used to
have a 75mm Rodenstock Grandagon-N with about five of these tiny little
"bubbles" and they did not seem to impact performance in any way (they
did effect the resale value when I sold the lens, however).
Kerry
From: dickburk@ix.netcom.com (Richard Knoppow)
Kerry, These are bubble like separations seen in the _body_ of the
lens rather than at the edges. The paint problem you mention is seen
at the extreme periphery of the lens and seems to be pretty common on
old lenses.
If you shine a light through the lens from either side the
separation will be obvious, but sometimes it isn't under more casual
inspection, just as scratches sometimes aren't obvious until lighted
up.
---
First, when you use a smaller format, you use a shorter lens to
achieve the same perspective, and, for the same exposure, achieve
greater depth-of-field. This has an effect equivalent to increasing the
speed of the film. It doesn't improve the quality of a well-taken
picture, but does improve the chance that a poorly-taken picture will
produce a passable image.
Second, it has been estimated that all other things being equal, the
cost of a lens increases with the cube (third power) of its diameter. A
smaller format simplifies mass production of lenses. Of course, from
this standpoint, the decision to make APS even more oblong that 135 is
totally indefensible!
Let it be known that I agree that a new medium format is long overdue
(for professionals and serious amateurs, not snapshooters) and would
shoot a lot more in medium format if I could afford a decent camera.
Rob
Date: Thu, 4 Jun 1998
Ernest Abbe and Otto Schott did their research on glasses for camera lenses
in the 1880's, I believe. Abbe made microscope objectives from flourite in
1884, if memory serves. Crown and Flint glasses were well-known, but these
researchers, working with grants from the Prussian government, were the
first to do work on new glasses specifically for lenses (the market for
optical glass being so small as to attract little investment). I cannot
imagine anything like patent protection inhibiting post-WWII Japenese
glassmakers from making use of the Schott technologies.
David Foy
Date: Sat, 6 Jun 1998
Schott is a member company of the Zeiss Foundation. They will be a preferred
source. But Bob S. is right CZ will buy from other sources when it suites
them.
Some types of optic glass may give a lens a slight difference in color. The
T* -coatings also compensate for these differences. So "cold" glass will be
compensated by the T*-coating to give a lens a somewhat "warm" color in line
with
the other lenses.
As a result all CZ-lenses have the same "color".
Ferdinand Stutterheim
Date: Wed, 3 Jun 1998
Generally speaking, optical glass is optical glass. I have watched
Schneider lenses being ground from blanks supplied by Tamron. Optical
glass is simply a commodity, traded like any other, and optical companies
buy from the cheapest supplier at any given time. Now this does not apply
to special glass types like some of the UD glasses, which are made to
particular specifications for one firm only.
German lens designs tend to be "warmer" and contrastier, and this applies
regardless of where the lenses come from. For my Contax RTS III I have
some lenses from Japan and some from Germany, and their characteristics are
identical.
Bob
Date: Wed, 3 Jun 1998
Many thanks. You've confirmed what I suspected must be the case.
That is clearly the situation today and in the recent past.
However, I could imagine a time, many years ago, when Japanese and German
glasses were not traded. A glassworker I know (a glassblower, but not an
optical designer) tells me that local materials and technologies result in
slightly different glasses -- for example, glasses are changed slightly by
minute quanties of compounds leached from crucibles. His concern is color,
not optical qualities. In 1965 I had a college roommate who was an Asahi
Glass employee, seconded to the US for graduate studies, who told me much
the same thing. He wasn't specifically talking optical glass either.
From what I know of the situation in Japan and Germany in the first decade
after the war, they stayed pretty self-sufficient in things like
manufacturing equipment, tooling, crucibles, etc. The Japanese in particular
were pretty strapped for money to import anything.
This might have been the situation up until the Yashica-Mat, Rolleicord era
(circa 1960). In, say, 1955, I can imagine bulk optical glass being shipped
around Europe, but halfway around the world? Schneider buying blanks from a
Japanese manufacturer in 1955-65? Possibly. Interesting question.
Having said that, I tend to agree with you that what we're discussing is
probably due to design differences or different ideas about process control
during manufacturing.
I can't put a finger on exactly what the "warmer" character is -- maybe it's
really only more contrast. I ran my tests on transparency film and I don't
have a finely-tuned color sense. I don't associate "warmth" with contrast.
Maybe I'll re-test with black and white, where variations in contrast will
be easier to spot.
_____________________________
Date: Wed, 3 Jun 1998
As an extreme example of this phenomenon, years ago I worked in a
university photo lab printing photos shot by the staff photographers.
About half of them used Nikon SLRs and half used Leica M.
We knew who used what, and would always use one filter softer when printing
the Leica stuff to match the Nikon. So we would typically print Leica negs
with a number 2 Polycontrast filter and Nikon with a number 3 to get
matching prints.
The Leica lenses were not really sharper, but images looked sharper due to
greater contrast. Leica uses a characteristic called Edge Spread Function,
a specialized version of MTF, in designing their lenses. I don't think
anyone else does.
Bob.
Date: Thu, 04 Jun 1998
Bob Monaghan wrote:
This last "quality" is one of the more important in lens design... where
a lens is optimized (or apotized) either for resolution (by
concentrating the rays into the center of the discs) or for contrast
(light airy core with ray contentrations at the fringes). Before the
'70s, designers biased for resolution. Now, they tend to bias for
contrast because the images appear sharper with normal enlagrement (more
common) but in fact have lower resolution and do not hold up as well
under higher orders of enlargement (less common).
Was it Bob S who mentioned in a previous post that Leitz had an
alternative to MTF in deriving this apotizing compromise for its lenses.
One can measure the tradeoff anyway one wants, but the piper must be
paid and this fundamental compromise does not change with different
means of measurement.
Eric Goldstein
Date: Fri, 05 Jun 1998
Of course there is also Kodak who named lenses according to quality
classification, e.g. Kodak Ektar, Ektanon, Anastigmat Special, Anastigmat,
etc. Ektar lenes are of at least five different types.
Nikon lenses of a certain vintage carry a code which tells the number of
elements. I think it is just simpler to use a brand name rather than
having to come up with a type name for each lens. I don't think they are
trying to keep any secrets.
The Japanese optical industry, including glass making, has a long
history. They got some help from the German optical industry during WW-II
but had a pretty good idea of what they were doing already.
Clearly, the styling of Nikon followed Contax and Cannon followed Leica.
The 50mm f/1.4 lens which made Nikon rangefinder cameras famous was a
Sonnar type but not a copy of the Contax Sonnar. I have never seen a
direct comparison between the two but from its popularity at the time I
suspect it beat the pants of the original Zeiss lens. My memory is that
the hot number for photojournalism was a Leica M-2 with a Nikon lens
adapted to it.
Optical glass making has a long history. The importance of the Schott
glass works was that it was about the first to apply a scientific approach
to finding out how to make glass with characteristics beyond the Crown and
Flint types known at the time. The impetus was from Ernst Abbe of Zeiss,
who wanted better glasses in order to make microscope objectives with good
color correction.
Although it was thought that anastigmat lenses which also had flat fields
could not be made with the old types of glass (due to Petzval) it was
discovered after the turn of century that they could. The Busch Omnar lens
of Martin can be made entirely with old glass types and still be fully
corrected. (This is a four-element air-spaced type). Of course, the
extended range of constants available from modern glass types make many
types of lenses possible and makes the designer's job easier.
----
Date: Fri, 5 Jun 1998
There was a tradition in the German optical industry of creating, selling,
promoting, licensing, and -- in essence -- "branding" lens formulas, from
the 1890's onward. There was a revenue stream, for instance, in licensing
the Tessar design and/or the Tessar trade name.
Elsewhere, in the US and in Japan, no marketing tradition existed to exploit
patented designs with trademarked names in quite the same way. Kodak created
a series of lenses called Ektars, originally derived from the Tessar formula
(after the expiry of the Tessar patent, I believe), but quickly departing
from the formula and breaking new ground. Soon the name Ektar was applied to
all kinds of designs and optical formulae.
Branding a series of designs, rather than a single design, is not bad
marketing, since virtually no lens-buyer is familiar enough with optical
physics to care. The Ektar name became trusted, just as the Tessar name was
trusted, because a body of experience grew up around the name, not because
anybody thought about the degrees of freedom, number of air-glass surfaces,
intersection point of principal ray with whatever. The nearest thing to
widespread comprehension of lens formulas is the misconception that the
number of elements is some kind of absolute indicator of quality, which it
surely is not.
The Japanese adopted the practice of branding lenses with the company name
after experimenting with alternatives. Yashica's first TLRs had Tri Lausar
lenses, and the later ones had Yashikors -- same lens. Nikon made lenses for
Canon (or was it the other way around?) and Canon's rangefinder lenses were
Serenars before they became Canons. In deference to the misconception that
more elements equals a better lens, for many years Nikon called its lenses
Nikkor-something, with something being a letter, d, e, f, g, etc. Nikkor-G,
for instance. The letter was a key that told you the number of elements in
the lens, in case you were interested, and I think G meant, simply, seven
elements.
Here's a question for more knowledgable members of the group:
The older practice is no longer honored in Germany, I am told. I don't
believe for a minute that the wide-angle Elmarit and the medium-telephoto
Elmarit are the same formula -- but I could be wrong. Am I?
When you have a Rollei with a Tessar in your hands, you know primarily that
it has a reputation for quality. The average person is unlikely to know the
lens is a four-element, three-group assembly, completely unsymmetrical, with
a plano-convex front element separated from a biconcave negative element by
an air space, and a rear element composed of a cemented biconcave or
planoconcave negative element and biconvex positive, with the diaphragm
between the cemented doublet and the biconcave negative (I just copied that
from a book -- I don't have it memorized). My point being, it's the name we
know and trust, not the formula. If the name Tessar was on a series of
high-quality lenses, from wide-angle to telephoto, each obviously of a
different formula, the name would not lose its power to identify a quality
product.
(My source for much of this is from what I remember of reading Kingslake, by
the way. I believe it's accurate, but this is a post to a mailing list, and
not an exercise in scholarship. Please let me know if I've got facts wrong.)
_____________________________
[Editor's note: Not all early uncoated lenses were color corrected, some
earlier lenses were corrected for pan or ortho film use only...]
From: "Patrick Bartek" bartek@skylink.net
The problem with uncoated lenses is flare. The internal reflections
off every uncoated surface reduces total light transmission sometimes
to less than half and this causes the low contrast. Because of this
shooting color with them is not recommended. You get color casts
because of chromatic abberations. These lenses were designed before
color and were corrected for the b&w; film of the day, which was
orthochromatic -- mostly sensitive to blue light -- instead of
panchromatic.
They can still be used for b&w; with good results, if you follow a few
simple rules. Avoid high contrast/high flare scenes, particularly
ones with bright highlights or reflections. Using contrast filters to
reduce the red and green primaries will improve sharpness. Orange
seems to be the best. Remember most of these lenses suffer from major
chromatic abberrations. Also do Zone tests for EACH lens. Because of
light loss due to internal reflections and the resulting low contrast,
the numbers you got using modern, coated lenses won't be good.
If I remember correctly, there was a series of articles by Wisner in
View Camera magazine about using uncoated as well as coated post WWII
lenses. It was very comprehensive.
--
NoLife Polymath Group
[ed. note: many people shy away from the longer telephoto cheapy lenses,
yet they can provide a lot of reach for low cost - from $40 to $100
used]
From: "David Foy" nomail@this_address.please
I had one about twenty years ago. I put a 2x doubler on it, used a
whacking great tripod, and got some shots of early-Fall prairie landscapes
around the Hand Hills area west of the Saskatchewan border. The lens did
just the right things to the shots -- flattened the perspective mightily,
softened and diffused the warm autumn colors, yet was plenty sharp enough
for the shots I wanted. I couldn't read the lettering on a stop sign a
mile away, but it gave a nice interpretation of the textures of the rows
of hay bales, the dusty gravel road disappearing straight to the horizon
over the low, rolling hilltops, the rust-colored grain elevator rising out
of a poplar grove five miles off. Don't expect it to match a $400 lens and
take it for what it is, and you can have some very satisfying photography
with it.
From: ctlee@hknet.com
On Mon, 08 Jun 1998, ed romney romney@edromney.com wrote:
Another good method is shooting a high contrast light source,
such as the Sun. Non-multicoated or poorly multicoated lens
will show large pieces of aperture shape flare.
Something, U can even see it on the ground glass.
From: dickburk@ix.netcom.com (Richard Knoppow)
Ghost images or images of the diaphragm have much more to do with
the design of the lens than with coatings, although coating will
reduce the effect when it is present.
I have several old, uncoated lenses which do not produce ghost
images. The main effect of lens flare is to generate an overall glow,
which tends to fill in shadow areas and reduce the saturation and
purity of colors in color photography, and to produce halos or flary
areas around bright objects.
While the advise of often given to use lens shades to reduce flare
of uncoated lenses, a lens shade has no effect on light going into the
lens to produce an image. They are mainly useful in cutting off
non-image light which causes flare by bouncing around inside the
camera.
Multiple layer coating extends the range of colors over which the
coating is effective. A single layer is effective at a single color
and its effect falls off on either side of that paticular wave length.
Because the range of colors used in normal photography or visually is
only about an octave, a single coating is practical. Multiple
coatings have a broader band of effectiveness. By using several
coatings of the right materials and thicknesses it is possible to make
the lens surfaces nearly completely non-reflective over pretty much
the entire bandwidth used for photography. For those with backgrounds
in electronics coating is related to filter theory and transmission
line theory. Essentially, a coating forms an impedance matching
section between the air and glass.
The fewer glass-air interfaces there are in the lens the less the
effect of coating will have on its performance.
---
Date: Tue, 26 May 1998
Fungus generally has a fine feathery or hairy look although it can form
spots like mildew. This doesn't sound like fungus although it may be
etching of some sort. I've seen marks on lens coating that look like water
spots on a negative. I am not sure what causes this. It doesn't come off
with cleaning but, if the marks are small and few, shouldn't have a
significant effect on the image. On the chance that it may be some
substance which lens cleaner won't dissolve you might try a little reagent
grade Acetone on it. Acetone is the standard lens cleaner used in optical
shops. Be very careful not to get any on and painted surface and hold the
lens facing downward so that none runs into the mount. A little on a
cotton swab is enough.
Fungus which has been allowed to stay on a glass surface for any time
will etch it. When these surfaces are examined under a loupe they can be
seen to be pitted. Much of this acts as an efficient diffuser ruining the
lens. I don't think this is what has happened here.
----
[Ed. note: why some lenses are setup to let you focus past
infinity...]
rec.photo.equipment.medium-format
Thomas J. Gilg tomg@cv.hp.com wrote:
Yes, but.
Temperature changes sometimes cause focus shift, especially
with long lenses. For that reason, many long lenses let you
focus past infinity. I can't remember whether the Pentax 300mm
lens is one of those or not.
--
Newsgroups: rec.photo.equipment.medium-format
Thomas J. Gilg tomg@cv.hp.com wrote:
Yes, but.
Temperature changes sometimes cause focus shift, especially
with long lenses. For that reason, many long lenses let you
focus past infinity. I can't remember whether the Pentax 300mm
lens is one of those or not.
--
From: godders@netcom.com (Godfrey DiGiorgi)
I'm no optical engineer so this explanation is likely a bit muzzy at
best.
1)
f/numbers are a ratio of the focal length over the physical lens aperture
mechanism. So a 28mm f2 lens has a physical aperture mechanism that's
14mm across, where a 300mm f2.8 has a physical aperture mechanism that
107mm across. In theory at least. The size and shape of the glass in the
optical elements which produces a given focal length are not a consideration.
2)
The size of the optical elements required is linked to both the lens
design type and the size of the format the lens is required to cover.
Take for instance a Ricoh GR1 and a Nikkor 28mm f/2.8 SLR lens. Both are
covering a 24x36mm format frame, but the Ricoh is a 7 element "Sonnar"
or "Distagon" type lens formula (very loosely, they seem similar to me from
the pictures o f the lens cross section I am looking at) where the Nikkor
is an inverted telephoto type objective, which it has to be in order to
allow enough physical distance for it to clear the swinging reflex mirror
etc. The Ricoh lens sites very close to the film plane and has more
equally sized elements front and rear while the Nikkor requires much
larger front elements in order to provide clean format coverage. This
gets more extreme as you look through shorter and shorter focal lengths.
It certainly has to do with the angle of acceptance of the lens relative
to the format coverage.
Long lenses, on the other hand, have relatively small angles of
acceptance and therefore the curvature of the elements doesn't have to be
as much a part of a sphere as short lenses have to be.
The relationship to format coverage is demonstrated again when you look
at a similar optic designed for a larger or smaller format. A Zeiss 16mm
Hologon for 35mm, for instance, is a massive piece of glass compared to
the miniscule 15mm Complan lens used in a Minox 8x11mm format
subminiature camera. The latter is less than 2/3 the diameter of a dime.
Similarly, a 50mm wide angle for 6x9 format field camera with an f/5.6
aperture is as large or larger than a 50mm f/2 lens for 35mm with respect
to its glass, even though they are the same focal length. The 6x9 format
lens has to provide clean coverage for a much much larger frame area and
needs a much bigger piece of glass to do it.
I've certainly not given a technical answer here with appropriate
formulae and such to calculate the optics required, and I look forward to
seeing something like that as this is an interesting question. But
hopefully I'm not too far off on the underlying relationships for why
things are the way they are.
Godfrey
rec.photo.equipment.medium-format
Larry,
Diffraction is a function of aperture and only becomes a problem, IMHO,
around 1mm (e.g. 24mm @ f22). I shoot my 6x7 lenses at f22 all the time
without problems. Your 75 at f22 has an aperture over 3mm, so don't worry
about it.
Ed Saus at Lesaus@aol.com
rec.photo.equipment.medium-format
The purpose of coating is to increase the amount of light transmitted
through the lens and decrease the amount reflected away. Coated lenses are
thus faster and less susceptible to flare. The coating itself does not
determine the lens' usefulness for color photography. That is a property of
how the lens designer tackled the problems of focusing different parts of
the spectrum on the film plane. An uncoated Apochromat will give superior
color. A well-designed triplet will, too, whether coated or not. If a lens
is older than about, say, the end of WWII, and not known as a good lens with
color, you should try it with a roll of color film and see how it works.
Date: Mon, 29 Jun 1998
An element or group of elements which can move when the lens is focused.
This allows the lens corrections to be optimized for different subject
distances. A normal lens can be corrected for spherical aberration and
coma at only one distance. For normal camera lenses this is usually
infinity. When used closer than about seven times focal length the
aberrations start to become noticable so the lens needs to be stopped down
for good sharpness. At some point the loss of sharpness from diffraction is
going to be worse than the aberrations and the performance will be poor.
Moving part of the lens by means of a cam or other device permits the
correction to track the focused distance to some degree so a lens with a
"floating" element can work well at both long and short distances wihtout
having to be stopped down excessively.
----
From: jsabo@vss.fsi.com
rmonagha@post.cis.smu.edu (Robert Monaghan) wrote:
snipped a lot of very good points
> How do the other costs break down? TIA ;-) grins bobm
Don't forget about the law of diminishing returns. The name brand prime
lenses may be only a few percent better in performance, but the majority
of the design and manufacture cost is probably related to those few percent.
The same applies to mechanical fit and finish, and lens feel. That little
bit of extra quality generally cost disproportionally more to produce.
Then there's the amortization of the design/tooling cost. 3rd party
manufacturers use the same design on lenses sold for a variety camera mounts.
Thus the non-recurring costs are spread out over a larger number of lenses,
and the piece price goes down.
Now take these up front cost differences and multiply by the markups
previously referred to, distributor, importer, wholesale, retail... and you
can see the difference in cost can often be accounted for. As to weather or
not all this justifies the final cost is another question.
Regards, Jim
Date: Wed, 8 Jul 1998
I basically agree that the performance gains relative to cost increses are
fairly small. However, there are some examples of substancial performance
increases too. The Leitz Apo Telyt, which for several years was a
classified piece of equipment only available to the US Navy, has a
substantially higher performance. It has achieved ON FILM resolution of
over 300 liner per millimeter, however, that was with special films from
Kodak and Agfa. But it also has extended correction for red and infrared,
making it one of the few lenses which do not require refocusing when used
with infrared film. Since its introduction Leitz has introduced several
other lenses with equal performance figures. including the new Vario Elmar
80 - 180, which currently is by far the best Zoom lens ever made.
Certainly, Leicas and Leica lenses are not for everyone, but it is to
their credit that to this day they have not sccumbed to mass marketing and
mass production, giving at least a choice of a high performance
alternative. I must admit, however, that besides my Leica
equipment I am not ashamed to use a Nikon with Nikon lernses also. At least
that way I can't be accused of being partial to just Leica.
Anyway, it is also nice to see that we can engage in meaninful discussions
like this without getting too defensive if our equipoment is not the very
best out there, or if other people do have other opinions.
Thanks for your kind reply.
Best wishes,
Heinz Richter
Date: Sun, 21 Jun 1998
I don't know the exact answer, but seems U mixed three things up - phyical
aperture diameter, the size of front element, and the numbers of elements.
I BELIEVE for prime lenses, the phyical diameter of the aperture (where the
aperture blades are) determines the effective aperture of the lens. For
some lenses, the aperture diameter may look pretty big from the front
or back, but they are actually pretty small once U strip down the lens.
Large and huge numbers of glasses are due to the fact that the wider the
lens, the harder the distortion can be corrected. Distortion is not
a major problem on super-tele lenses. This is also why in recent years,
AL elements are widely used on wide angle lenses (including zooms) to
suppress the distortion.
regards,
Alan Chan
In rec.photo.misc you write:
Date: Sun, 21 Jun 1998
Robert,
A wide angle lens has to accept light from angles like 70 degrees (and
over a shorter focal length) instead of say roughly 40 degrees for a 180mm
lens. It is a simple geometry problem. As the focal length gets shorter
and the required angle of acceptance gets larger the opening up front gets
huge or the image gets cut off (vignetting). As such the glass has to be
larger in relation to other tele lenses in order to have the field of
coverage. Also, because each element in a wide angle lens have to bend the
light at such a radical angle the bigger the front lens element is, the
less of the edge of the element you have to use and the edge of the lens
elements are optically the worst. Different wavelengths of light refract
at different angles and are effected by the variation in glass thickness
(edges). So, a wide angle lens often uses aspherical elements which are
usually molded glass or plastic. An aspheric element is one which does not
have a shape that is a constant radius (a section of a circle). All this
drives lens designers to have to use more elements, larger front elements
and more expensive materials. A good fast wide angle will not only be
large but will cost a lot!
Just for grins I will tell you that I am on a team designing a wide angle
lens where I work and one version has 12 elements and several aspheres.
The tooling cost to mold such a lens can be in excess of 1/2 a million
dollars! The pecision coatings that are applied to the glass in a vacuum
are sometimes 10-20 microscopic layers of different rare materials.
Dave
rec.photo.equipment.large-format
Brian Downey downeybr@pilot.msu.edu wrote:
The Syntor is a four-element air-spaced Dialyte or Celor type lens,
the same basic design as used for the Dogmar and Artar. It is
symmetrical.
Goerz originally made two series of Celor type lenses, an f/4.5 and
an f6.8 under the name Goerz Double Anastigmat, Series B. In 1904 the
trade names of all Goerz lenses were changed. The f/4.5 version became
the Celor and the f/6.8 version became the Syntor. I have never seen
one of these in the flesh and don't know how good they are but some
really excellent lenses have been designed around this type.
If it has a colored reflection it is probably tarnished rather than
coated, unless it is an old lens coated long after manufacture. This
sort of tarnish often has a bluish tinge, very like a single coating.
Sometimes it has a rainbow "oil slick" look. This tarnish works like a
coating. In fact, it was the discovery that the transmission of
tarnished lenses is greater than freshly polished ones which led the
pioneer lens designer H.Dennis Taylor, inventor of the Cooke Triplet,
to the discovery of the principle of lens coating.
The serial number indicates this lens was made sometime around 1908
to 1909. The patent is from around the late 1890's, I don't have a
copy of this one, it is probably von Hoegh's original.
Goerz American advertised the Syntor during WW-1 as a substitute for
the Dagors and Dogmars which were not available then.
The lens list in Henney and Dudley gives the coverage as 64deg.
This seems to me to be rather large for this type of lens, although
coverage of the Celor is given as 70deg. The Dogmar, a more modern
design covers 48deg and I suspect this is closer to the truth for the
Syntor.
---
rec.photo.equipment.large-format
Oh yes, glass can tarnish. The chemical resistance as well as mechanical
properties of optical glasses vary wildly and may be quite different
from that of ordinary soda-lime glass. Schott classifies in their
catalog the climate resistance (CR), stain resistance (FR), resistance
to acids (SR), and resistance to alkaline solutions (AR) for each glass
type, and other glass manufacturers probably do the same. Some glasses
cannot be used as front or back elements because they are too easily
damaged even by pure water... (not to speak of acid rain etc.)
In the case of your Heliar, make sure it is not just a surface film of
residue, and that it is not a coated lens (lens age?). Old
disintegrating coatings can look very similar to tarnished glass. If it
is tarnished, you cant do very much about it. Tarnishing should not
occur if a lens is always kept clean and dry. Saltwater spray and sweat
are especially dangerous - not only to coatings, but also to the glass
itself..
In the really long run, all glass is bound to tarnish by
recrystallizing: Glass is an undercooled liquid and thus unstable in
principle - but at room temperature (and without chemical attack) it is
usually going to take at least a few thousand years.....(some of the
iridescent colors of Roman glass ware from BC times are due to
recrystallization)
Arne Croell
rec.photo.equipment.large-format
Scott Knudsen s.knudsen@sk.sympatico.ca wrote:
It is certainly NOT the lens coating:-) Modern coatings are vacuum
deposited and form a strong bond with the glass, and are nearly as
hard as the glass (maybe harder than some types). They are very
difficult to remove, usually requiring the use of Hydroflouric acid.
---
[Editor's Note: Related posts also pointed out correctly that you should
obviously not be using hydrofluoric acid in any case, as a dangerous and
controlled reagent, and one which would also dissolve the lens' glass!
rec.photo.equipment.large-format
Its a combination of oxidation and the effects of water vapor over a
very long time. Not all glass does this, optical glass varies widely
in stability. In any case, modern lens coatings eliminate this.
Corrosion or tarnishing has little effect on lens performance other
than to, perhaps, improve it a little. As long as the glass is clear
and free from any haziness it should work well.
Its likely that the conditions under which the lens was kept for
most of its life have an effect on whether and how much corrosion
appears.
I have a Zeiss Tessar from the late 1930's which has a bluish tinge
to the front element. I thought that this may have been coated, since
Zeiss was applying hard coatings to some lenses as early as 1935, but
only the front surface of the front element exhibits the color tinge
so its corrosion. The other lenses I have or have seen with this
effect are all very much older.
---
rec.photo.equipment.large-format
You may want to check out this month's View Camera Magazine on the
subject of lens coatings. I mention the tarnishing of lenses in
this article. In fact, in many cases, the tarnishing can acutally
be beneficial because of the interferometric effects it has which
is similar to the modern antireflective coating. In about 1903
Dennis Taylor of the Cook Company in England actually patented a
caustic "Tarnishing" process in order to reduce reflections. The
problem, as you might imagine, was that it was not very reliable.
Ron Wisner, Wisner Mfg
rec.photo.equipment.35mm
A Seattle camera shop had its annual garage sale - moving along things
that wouldn't sell. I found 4 Nikkor lenses the Nikon lens bin:
35mm/2.8, 50mm/2.0, 43-86mm/3.5, and 135mm/2.8. To say that they're
well-worn is a complement. All were priced between $20 and $35. I
checked out basic operation and they were fine, so I bought them all. I
got them home, cleaned them up, loaded the F2 with Fuji 100 film and did
six test shots with each lens. A good local 1 hour photo processor
returned perfect pictures to me. I can't tell the difference between
these beat-up lenses and my pristine Nikkors.
These lenses have dust particles inside, fingerprints etched on front and
rear elements, one front element scratch on the edge, and lots of dings on
the external framework. Nonetheless, they provided excellent contrast and
sharp photos. A complement to Nikon and a good lesson on the effects of
internal dust particles and minor blemishes.
John Shuster
rec.photo.equipment.large-format
"Color Correction" is one of the most misunderstood factors in lens
evaluation. "Color Correction" does not relate to "Color Fidelity" It
deals with the phenomenon that different colors (wavelengths) of light will
behave differently in the same glass. That is to say, they won't all focus
at exactly the same place as each other. As a practical matter this
translates into "blurriness" either in color medium or, as importantly, in
black and white. Panchromatic black and white film perceives all the colors
in white lite. A lens is no more or less suitable for color or black &
white whether it is "color corrected" or not.
I don't know if there are any ways of testing "color fidelity" of a lens.
SKG
rec.photo.equipment.35mm
On Mon, 20 Jul 1998 18:22:16 -0400, "Sherry L. Laflamme"
seaangel@seacoast.com wrote:
B-a-a-a-d...! ;-)
Ideally, an evenly-illuminated subject would be rendered the same way
on film, but optics and economics sometimes dictate the acceptance
of less than ideal performance, so most lenses render images that
are darker at the edges/corners (softly... - sharper-edged darkening
is called "vignetting", usually caused by filter rims and shades that
are too deep, and cut into the image). This effect is worst at the
widest stops, and stopping down a bit often cures the problem.
David Ruether
rec.photo.equipment.35mm
"Light falloff" isn't terrible, but it's something you usually don't want.
It means that the image gets gradually darker as you move away from the
center; in other words, the center of the picture looks OK and gets darker
toward the corners. Often it isn't too noticeable in "busy" subjects, but
if you take a picture with large areas of even tone (such as a cloudless
blue sky) the dark corners can be very distracting. The darkening is
usually worst at full aperture and gradually improves as you stop the lens
down. (This is NOT the same as "vignetting," in which the corners are dark
because something, such as a filter or a lens hood, abruptly cuts off the
light rays at the corners. Vignetting usually gets worse as you stop down,
because increasing depth of field brings the filter or whatever into
sharper focus.)
Light falloff is an inevitable consequence of forming the image on a flat
film plane -- the corners of the film are farther from the lens than the
center is, so the light rays have farther to travel and are reduced in
intensity according to the good ol' Inverse Square Law. Wide angle lenses
are most prone to it, because longer lenses tend to even out the
differences in distance between center and corners. However, with any
focal length, there are tricks optical designers can do to minimize the
effect of light falloff, and a good lens will show little or none of it at
moderate apertures.
Date: Thu, 23 Jul 1998
From "The Rollei Manual" by Pearlman (1955) :
"Your Rollei is a precision instrument with more than 300 separate moving
parts in it..."
"Always keep the Rollei double lens cap in position over the lenses except
when actually using the camera. Optical glass is really very soft, it
tarnishes like silver and is easily attacked by weathering spots, caused by
impurities in the atmosphere."
( Coal was a major source of fuel at the time this book was written.)
......
"Whilst some people can use a camera in the hand for as long as 1/10th second
exposure without showing any trace of movement, there are others who cannot
even hold a camera steady for 1/100th second! To test your own ability in
holding your camera steady, attach a small hand mirror to the front of your
camera by means of rubber bands and with the sun shining through your room
window, hold the camera in the beam at an angle to the direction of sunlight.
Direct the reflection from the mirror across the room to a wall 15 or 20 ft.
away, so that the bright spot falls on a definite point, say the corner
of a
picture frame, or similar suitable point. Watch the reflecion dance about as
you try to hold it still, both at waist level and then at eye level. If you
find it extremely difficult this simple exercise will prove very good
practice."
R. J. Bender (A Nikon, Mamiya and Rollei user)
Date: Mon, 27 Jul 1998
In reply to the suggestion to use a blower or alcohol, remember that
Nikon does not recommend this for ED glass as the glass is easily
damaged by extreme temperature change (stream of air)and solvents.
Stewart.
[Editor's Note: See SIGnificant
MAlfunctions link for more plus and minuses on Sigma lenses...
From: madmat@ix.netcom.nospam.com (Matthew Y. Hayashibara)
"Vivace" vivace@shaw.wave.ca
wrote:
*Some* Sigmas are mechanical nightmares.
This seems to be a design flaw with the lenses that have the rotating
front element for focusing. If the focusing ring hits something, or if
something prevents it from turning (photographer holding focusing ring
when the lens is attempting to AF) the soft plastic of the ring gear
gets chewed up and prevents the helical that focuses the lens from
turning... resulting in a non-focusing lens. Replacing the stripped
gear is a fairly quick repair, but not inexpensive.
My bad experience was with the 70-210 3.5/4.5. The repair guy told me
that if you are religious about keeping a rubber shade on it all the
time (to prevent shocks to the focus ring) and careful to switch it to
MF (the Canon EOS models, anyway) before casing it the problems can be
minimized. I got rid of it and got the little Canon 80-200 before I
could try this... it seems to make some sense.
This doesn't seem to be a problem with some lenses, like the 28-105,
135-400, or 170-500 because these lenses focus by moving an internal
lens group. (I'm very happy with the 135-400).
I know the old design 70-300 DL is famous for having its front element
fall out... it was TAPED in! Sigma seems to have fixed this in the
latest iteration, though the focus gear problem remains. I have a
second generation 70-300 DL Macro that hasn't given any problems yet.
Stories of older EOS-mount lenses not being compatible with the newer
ElanII, Rebel G and IX cameras are legion... the either lock the
mirror or set the camera shutter to "B". Sigma has admitted to this,
and *some* of the lenses can be upgraded to work with these cameras.
(It'd be nice if someone had a list of the models to avoid...)
But other than that (har!), they seem to be pretty good lenses
optically, and well corrected with apochromatic and aspheric designs
with low dispersion glass and multicoating. Perhaps the mechanical
designs are improving, but Tokina and Tamron are a moving target!
MadMat
From: steven T koontz skoontz@mindspring.com
Joe Capasso wrote:
Very true.. I'm amazed how little lens defects affect the actual
picture.. I bought a Med format minolta this weekend ($50!) with the
front element scratched all to h%ll.. I took lens apart and cleaned
everthing as good as I could (cool thing about MF stuff is the
elements just unscrew!) and tried it out.. The thing is almost as good
as one I have with perfect glass.. If I hadn't shot both side by side
as a test, I would have never known there was ANY difference.. It's a
very usable camera but if someone who didn't know better looked at it
they would think it was junk.. People get way to anal about the
condition of a lens.. I would rather have a scratched up "good" lens
than a new "cheap" one.. You're not focusing on the elements so this
stuff doesn't show up..
From: Jeffrey Karp jeffkarp@erols.com
It would be interesting to see comparison images from many damaged
lenses to try to get a feeling of what will really impact image quality,
and what will have an insignificant effect. I often see damaged lenses
being sold at about a third of the price of good condition ones. I
was almost tempted to buy some a few times. I guess if you have
two weeks to return them, all you can really lose is the cost of taking
test photos. I guess many people still don't like ugly equipment, even
if it functions decently.
Editor's Note: From Nikon Digest
As always, prevention is better than correction.
So, before changing / dismounting lenses, you have to make the following
preparation:
1. Prepare the lens to be mounted. Loose the lens backcap, to
facilitate quick mounting to the camera.
2. Prepare the backcap for the to-be-dismounted lens.
3. Prepare the camera bodycap, if you want to have lens dismounted from
the camera for the long time. This will not prevent dust, but other physical
damages as well such as accidental damage by your own finger.
4. Blower, to blow-off any dust inside the camera.
5. Place all the camera, lenses and other equipment in the relatively
dust-free & wind-free location. If this is not possible (such as in the
dessert, or in a carpeted room of a wedding ceremony), use your body /
jacket / car as an emergency shelter for your camera.
After you complete the preparation, the lens changing process is fairly
quick and dust-free:
1. Dismount the used lens from the camera, place it so the lens back is
facing up.
2. Open the loosened backcap from the desired lens, and mount the
desired lens to the camera.
3. Place the backcap to the used lens, and tighten it.
If you have to take photograph in dusty/sandy/windy location:
1. Bring along your car as a shelter from dusty/windy/sandy location.
2. Anticipate your lens need (just ONE lens), and mount it before coming
to the photo site. This way, you don't have to change the lens in the middle
of dusty/sandy/windy location. The drawback to this method is that you are
limited to only one lens.
3. Borrow / Rent / Buy camera body/bodies. Install all the needed lenses
to each camera. You will have multiple lens without risking dust/sand, but
requires extra investement on your part.
4. Similar procedures apply if you need to change film in the
dusty/sandy/windy location.
Just remember, the sand and/or salt is the most devastating enemy to camera
& lens mechanics. It can scratch, jam, and/or rusting the camera's
mechanical element(s). Another common (and equally devastating) causes is
your own finger, and careless mounting/dismounting of the lens. Careless
mounting can damage either/both camera & lens mounting elements.
If you take discipline in performing lens-changing/film-changing procedure,
it will take a long time before dust reached your camera. And if it does, a
blower will certainly blow away a small dust. Never touch the mirror reflex
because it contains delicate sensors for exposure & focusing automation.
Never touch the shutter blades because of the delicate blades it contains.
I don't like to choose between mirror and shutter blades, but if I have to
make a choice, I feel I'd better sacrifice the mirror reflex (rather than
the shutter blades & TTL sensors) to accept the dust. I feel that it is
easier for me to blow-off dust from the mirror reflex rather than from the
shutter blades. After all, mirror lock-up isn't intended to prevent dust
from reaching the reflex, but primarily to minimize camera shakes during
macrophotography or using telephoto lens. That's why I never lock-up my F3's
mirror during lens change.
Warmest Regards,
From: FS@FS.COM (FS)
I bought the Tokina AF-20-35/2.8 Pro and I found the picture quality was
very good. However, when you buy it, you have to inspect it very
carefully. The quality control of Tokina really needed to be improved.
After I had gone to four different shops (Hong Kong) and inspected six
lenses, I finally got mine which was satisfactory in term of overall
quality.
Here were the problems you had to be aware:
Shop1: 1st lens-a big piece of black "dot" inside the lens. 2nd
lens-there were two scratches on the second lens element. It looked like
"peeling" of the coating. 3rd lens-irregular iris. The length of one
iris looked abnormally longer than the others.
Shop2: Something wrong with the zoom ring. It could only turn to 28mm
marking in the widest setting and pass the 35mm in the other direction.
(they only had one in stock.)
Shop3: same as the 2nd lens in shop1. (they only had one in stock.)
Shop4: I got mine in this shop.
FS
Please use the following address if you want to Email me:
ayu@hk.super.net
From: dickburk@ix.netcom.com (Richard Knoppow)
"Christopher M. Perez" chrisper@vnd.tek.com wrote:
That's about it. Lenses and mirrors are given a final polish with
the finest grade of rouge.
I would try every other possibility before doing this. If it is some
foreign substance on the glass you may be able to get it off without
anything as drastic as polishing it off.
I have seen a pattern of fine crevases on a lens surface, they look
like dried mud. I am not sure what caused this. Perhaps fungus but
also it may have been the result of unstable glass.
If this is a potentially valuable lens try John Van Stelten,
focalpt@ecentral.com who does this kind of work.
---
From: Bruce McLaughlin bmclaugh@primenet.com
I would absolutely not try to disassemble and clean the lenses yourself
unless you have precision tools an optical collumater and lots of
experience. I would send the lenses in to the manufacturer's official
service station for an estimate. Unfortunately, fungus on lenses, if
left long enough, etches the surface of the glass eventually making it
beyond reasonable repair. The lens may still be useable but it will not
be as sharp as it should and will undoubtedly have a fairly high flare
level. Of course, the fungus must not be left on the lenses. It will
only get worse and WILL destroy the lens in time. Frankly, if the deal
is not complete, I would opt out. Buying lenses with fungus is just too
risky in my opinion unless you paid perhaps $5.00 to $10.00 for them
which, I think is the most they are probably worth . . . unless . . the
fungus is very recent and hasn't yet etched the glass.
Newsgroups: rec.photo.marketplace
...not to get mired on this topic, but the ease of scratching a lens
coating has a lot to do with the coating hardness (if there is even a
coating). It does not take sand to chafe a lens. Sometimes all it takes
is using paper products or rough fabrics. Never clean a lens dry. Zippo
fluid (naptha) is a very good degreaser and it evaporates instantly.
From: Dont-use@this-address.com (Planar100)
I just learned from a guy who does service on Hasselblad gear that ZEISS
lenses have a soft coating, and as an effect cleaning marks are quite
common on these lenses.
Myself, I put a UV-filter on my new Zeiss lens immediately after I took
it out of the box; I haven't touched the surface of the front lens with
anything since then.
--
rec.photo.equipment.35mm
Lens flare results from extraneous light entering the lens.
Extraneous light is any light which is not required to form the image
on film. Each lens focal length has a specific angle of view, and the
light reflected from objects within that angle of view is what forms
the image.
For example, a 50mm focal length lens has and angle of view of 46
degrees. Yet, reflected light from within an arc of 90 degrees or
more will be able to strike the front element and enter the lens. All
of this extraneous light simply reflects back and forth on the front
and rear surfaces of all the lens elements, reducing image contrast
and color saturation.
An effective lens shade is matched to the focal length and angle of
view of the lens. Rectangular shades are more effective than round
shades, because the top and sides can be made longer without causing
vignetting of the corners of the image. A lens shade matched to the
angle of view of a 135mm lens will be about half the length of the
lens.
With a zoom lens which covers the range of focal lengths from wide
angle to telephoto, design of an effective lens shade is impossible.
An appropriate shade for the telephoto focal length will cause
vignetting at the wide angle lengths. Consequently, the lens shade
for zoom lenses must be matched to the widest focal length - and will
do nothing for the mid range and telephoto focal lengths.
The convenience of using wide to tele zoom lenses is inarguable. But
the price you pay for this convenience is a degree of loss in color
contrast and saturation due to lack of an effective lens shade - not
to mention the increases in pincushion and barrel distortion, loss of
edge sharpness and a variety of other aberations which detract from
image quality. If the best possible image quality is the issue, one
uses prime lenses and zooms with their feet. If convenience is given
priority over image quality, there is no point in loading film -
because cameras are equally fun to use whether or not they are loaded
with film, and the inconvenience of sending the film to a lab for
processing can be avoided.
For those who insist, image quality can be eroded even further by
attaching a UV filter. The filter in effect becomes the front element
of the lens, and receives no shading from the lens barrel at all.
Without an effective lens shade, the filter can gather extraneous
light from an arc of about 160 degrees and channel it right into the
lens. Much has been said about using UV filters to "protect" the
lens. The question is, protect it from what? Making good images?
From Medium Format Digest:
Typically, one large scratch on the front surface of the front element (if
distinct and especially near the edge) won't affect the image too much.
Though you may get some flare if indirect light enters the lens at a
particular angle (like the sun or any bright source.)
Scratches on the rear will affect the image much more so, especially like the
one on your lens (near the center.)
For your test shots, you should position the lens at various angles with
respect to the sun or other bright 'indirect' sources.) This should give
some indication on how the scratch induced flare behaves. If the two
scratches are 'sharp' and distinct, the flaring can be reduced or
controlled by filing in these scratched with a black opaque filler.
I think most of your problems will come from the rear scratch. Since it is
located close to the center of the element, the effects will be much more
pronounced with smaller apertures. And if you fill it in as I suggested
above, this will most likely reduce the amount of light coming through the
lens (i.e., f/16 may act more like f/22 or something like that.)
Remember, one or two large, distinct scratches (on the front element) will
cause a lot less trouble than a whole 'bunch' of tiny little scratches.
These will adversely affect the contract as well as the 'sharpness' of the
lens. Lots of fine small scratches or 'just scratches' on the rear element
is cause for REJECTION! One large scratch on the front element (especially
near the edge) is not a cause of instant rejection (if compensation is
made to the cost of the lens.)
Good luck in your testing!!
From Medium Format Digest:
The scratch on the front element shouldn't affect the image quality as
long as there's no sun hitting the front element. One technique I've heard
people do is to take a magic marker or something black and to fill in the
scratch to eliminate an reflection. Front elements are also, contrary to
belief, inexpensive to replace, provided you perform the labor yourself.
The glass is only like $100-200 for a zeiss front element. I don't know
about the rear element. It's probably a little more complicated to
replace, but I doubt it costs much, either, as it's generally not a
cemented group. Someone else on this newsgroup replaced the front element
of his zeiss lens, so you should read that. If you're considering
replacing both front and rear elements, you may as well pay the extra
$400-500 and get a lens with no scratches.
From Medium Format Digest:
Thank you to those who contributed answers to my recent post regarding
how to test the scratched 50mm C T* lens that I still haven't
received yet. If the tests show significant optical anomalies, I
might consider replacing the lens elements. I checked through old
postings and found that one MFD reader had replaced his own front
lens element on a 250/4 Zeiss lens. I e-mailed Zeiss in Germany
(info@zeiss.de) and inquired about the availability and pricing of the
front and rear elements for the 50mm C T*. The front element is DM160
(about $100) and the rear element is only DM60 (about $40). Not bad.
I'm now interested in two things:
1) I'd like more information regarding how to repair it myself to
see if I'm up to it. Jim Lebiedz is the guy who posted in the MFD that
replaced his own elements, but his e-mail is no longer valid. Has
anyone else tried this or know how to contact Jim for more info?
2) Assuming that I chicken-out on replacing the elements myself, does
anyone know of a trust-worthy repair shop that can handle replacing the
elements?
From: sgbphoto@aol.com (SGB photo)
Gene,
I have hundreds of sunrise/sunset photos and it has been my experience
that you can not completly eliminate flare when shooting into the sun,
however you can reduce the problem.
Wide angle lenses increase the probility of flare along with zoom lenses
due to the additional glass elements. Adding filters also compounds the
problem.
I have had the best results useing single-focal-length lenses and
apertures of f11 - f16.
If everything else fails, claim it was intentional for that special
effect. :)
Steve
From: "Michael A. Covington" covington@mindspring.com
Tiny amounts of grease on a coated lens will make it look like the coating
is missing in spots. So try a good cleaning. If not, I'd say go ahead and
use the lens anyway -- a mostly-coated lens is a *lot* better than an
uncoated one! Many people put completely uncoated Tiffen UV filters on
lenses and don't notice a problem.
--
Date: Sat, 29 Aug 1998
(ZaaX) wrote:
If you can return it or exchange it, then go ahead, as it sounds that it
will bug you for a long time to come.
If the pit is small, it will not have much effect. Perhaps the most
noticeable one will be a very small amount of flare, when there is a light
source in the picture. This will be caused by the small pit
refracting/reflecting some of the light rays.
If you have a steady hand and are very careful, you can take a very small
brush and some black matte paint and put a small dab on the pit. That
should take care of any flare.
--
rudyg@jps.net
From: Christopher S Own cso559@merle.acns.nwu.edu
Hi Everyone,
I just got a well-used DC Nikkor 135 from Korea. I was very happy
to get it, and the price was so low that I couldn't turn it down, so I
went ahead and took the risk.
Well, it turns out that the rear of the front lens element has
little tendrils on it. I've checked the archives, and answers aren't very
direct, so I'm posting this myself. The stuff doesn't seem like it would
substantially impacts image quality, but I don't want it to spread if it
is real. So, I have two questions.
1) Is this really fungus?
I cannot see anything when looking directly into the glass. I
must turn the lens at an angle from a bright light so that the reflection
from this light is seen in the glass (equivalent angle for 'viewing' the
coating on lenses, essentially the flare angle). Then, I see a large
number of tiny splotches 1-1.5mm and 4 or 5 small 'colonies' consisting of
tendrils, at largest 4mm in diameter. Whereas lens coating is vivid
blue/purple, the tendrils are flat whitish, but almost transparent color.
Keep in mind that this lens has a 72mm filter diameter, so this is
minuscule compared to the actual area of the element. Perhaps the lens
has been cleaned and this is removed coating? Or is it caked-on fungus
that died but was never removed? Or is it really fungus and I have a big
problem?
2) Who's best for removing this if it is fungus, and at what average cost?
I am currently in podunk-ville (Wichita Falls, TX) visiting home,
so there are no big repair facilities around. Do I shell out $$$ for an
appraisal of repair by Nikon? Can I get some small shop to do it?
A speedy answer would be appreciated. I am going to visit at least one
shop I know of here, but I don't think they do repairs. Maybe get an
opinion on what I should do. If anyone here has had experience (and
solved it), please let me know!
Thanks.
__________________________________
From: Christopher S Own cso559@merle.acns.nwu.edu
OK... taking your advice, I dumped the thing in the sun (under a glass
plate) for about an hour. I'm in Texas, the sun is pretty darn strong.
Then I unscrewed the front element and tried some windex. Well, nothing
happened. That is very weird because the only explanation I have is that
if this lens element is aspheric, the fungus might be attacking glue on
the inside. So, I called up Nikon and they said that the lens element is
not aspheric... So now the only explanation I can think of is that the
fungus ate away some of the glass, died, and left an uncoated spot.
This morning, I looked at the lens, and it seemed that the spots were
growing. I thought it might have been my imagination, but I decided, hell
with it, and put the lens under the noonday/afternoon sun for about 4
hours. For 2.5 of those 4, I had a glass plate over it.. but I decided to
take the glass plate off and expose the thing to straight sunlight for
another 1.5 hrs. The marks are still there, and how can I tell if the
fungus is dead? Another question is whether the fungus was already gone
to start with.
Price for repair is quoted between 149 and 199 for 'major repair.' The
lens is so valuable and I paid so little that I bet I could sell the thing
used and still get all my money back, including the repair. But while I'm
using it, I'd rather avoid spending another 200 bucks if it doesn't affect
any of my images. Plus, eliminating a possibly dormant spore-filled
element would definitely prevent further problems with other parts of the
lens.
Would a stronger solution on the surface perhaps help? Do you think I
should just splurge on a new front element? Any other options? Many
thanks for your advice.
__________________________________
From: bdd@cs.purdue.edu (Bozhidar Dimitrov)
Christopher S Own (cso559@merle.acns.nwu.edu) wrote:
: 1) Is this really fungus?
Sounds like it. It may not affect the image, and the only way to know is
to test the lens.
I had a valuable lens affected by fungus. i brought it to a professional
for cleaning, and he charged me $55. Later one, I tried cleaning fungus
for a friend, on a "trow-away" lens. It worked very well, and a year later
his lens is free of fungus.
I have a good set of screw drivers, and I have worked with fine mechanical
objects before. So I just took the front element off, cleaned it with a
50/50 solution of alcohol and amonia, then put it back together. Worked
like a charm.
I think that I seated the element just fine as the lens is as sharp as it
ws before my "repair." It was an older lens with everything metal inside,
so there was little posibility of messing up the set alignment.
Good luck,
From: James Mitchell jmitchell@cls.uob.com.sg
Hi Jo,
Here in Singapore where it is hot and humid all year round it is essential
to keep your equipment dry. The most favoured way here is to pack your
equipment into a dry-pack case. Its an *air tight* plastic box in which
you place silica gel to absorb the moisture. When the gel turns pink its
time to heat it up in the oven until its blue and then back into the box
(after cooling). Some people buy a refrigerator looking thing that
maintains a constant humidity, better than the dry-pack case but much more
expensive. I can vouch for usefulness of the dry-pack case.
Cheers
Jo wrote:
From: steved@united.ussinc.com (Steve Dunn)
The best way to prevent fungus is to keep it dry, and silica gel
will help. Silica gel, of course, has only a finite capacity to
absorb water, so you'll have to replace or refresh it periodically.
The easiest way is to get more and throw out the old stuff, but I've
heard you can also dry the silica gel yourself. I don't know how,
so hopefully someone else will mention how.
I've kept my cameras in camera bags for as long as I've had
cameras (about 20 years so far) and have never had fungus on 'em. I've
lived indoors in air-conditioned homes most of this time, so I haven't
had to deal with much in the way of humidity.
If you're really concerned, find some kind of airtight container.
Put the camera and some silica gel into it at a time when humidity
is low, and then close the container.
But to be honest, I don't think you have much to worry about.
P.S. good choice of camera and lens, from a fellow Elan II/28-105 USM owner
--
From Nikon Digest:
A couple of weeks ago I posted a query on this list regarding the use of
silica gel to protect equipment from fungus. I received some very helpful
replies. Thanks to all of you who helped me out.
I contacted Desiccare, Inc., and spoke to Brad Wolk (800-446-6650). He
confirmed that putting one of their "Pillow Pacs" (silica gel) into a
Ziplock freezer bag with each body and lens would be most effective. He
also suggested that I put in a Humidity Indicator Card (HIC) that will
show when the humidity in the bag reaches 50%. I took his suggestions and
purchased two packages of 3-gram Pillow Pacs and on package of 125 HIC
cards. The total with shipping was $54.90.
I'm confident that this system will do the job. From the HIC cards I can
see that my equipment is currently resting comfortably at approx. 30%
humidity. Brad also assured me that the silica gel will not take moisture
from the equipment but only the ambient humidity.
If anyone has any questions or comments, please feel free to contact me.
John Butler
rec.photo.equipment.35mm
I am wondering how much luck people have had in removing fungus from
lenses?
I have a Canon 100mm F 2.8 Macro (New cost today ~= $500 [US]) which
has fungus on a number of different elements. The lens has been barely
used.
I sent it in to the closest Canon repair shop and the cost to repair
it is about $115 with return shipping. They claimed the fungus had not
affected the coating on the elements yet.
I am wondering how other list members have fared with the removal of
fungus from coated lenses??
Thanks for the Information in advance.
Jim
James E. Gluckin, M.D.
rec.photo.equipment.35mm
I've only done one, but I found it extremely easy, using isopropyl alcohol
and lens tissue.
I'm told that leaving the lenses out in the sun for a few hours will kill
the fungus. I didn't do that, and the fungus didn't come back; there wasn't
much of it.
You will of course need a spanner wrench to disassemble the lens. $115 is
not exorbitant for cleaning a lens professionally. If you do it yourself
you'll get a tiny bit of dust inside the lens, but it won't do any harm.
rec.photo.equipment.35mm
I did that when I was in the Philippines. There's no special design needed
for the cabinet. I just wired a 60 watt bulb into the top of a kitchen
cabinet, removed the top shelf, and put my equipment on the bottom shelf
(uncased). The warmth will create enough circulation as long as you don't
actually build something that's airtight. Don't put the bulb closer to 18
inches or so to anything (not so close that the metal would get
particularly warm to the touch).
rec.photo.equipment.35mm
All you want, actually, is to keep the cabinet maybe 10 degrees warmer than
ambient air, so that the relative humidity in the cabinet is always low.
Avoid extreme heat.
From: canongirl@hotmail.com
Hi, I live in Hong Kong and the humidity there is just ridiculous. What
I do
to store equipment is using a couple of air tight big storage boxes and put
3-4 packs of silica gel inside. The moisture should be able to get
sucked up
by the silica gel. You could find the gels anywhere if you live in a humid
country :)
Sincerely yours,
From: foo@bar.net (Clark Anderson)
I live in Hawaii, land of humidity. Mold and mildew grow on everything.
I bought 2 military surplus ammunition cases. They measure 15" long,
12" wide and 14" high. The lid has a rubber gasket for sealing. The lid
clamps down with 4 buckles, one on each edge. Completely airtight.
I built some removeable shelves of metal mesh and 1/4" threaded rod, each
box has 2 shelves in it. I bought some silica gel dessicant from a
science supply company and put it in the bottom in a shallow dish.
Each box with 2 shelves is enough to hold 2-3 camera bodies and a
half-dozen lenses. You could probably get more by adding a third shelf.
Total cost for each box: about $35. Plus you don't need electricity.
The part specification stamped on the top of the box is:
If there's any interest I can post some digital pictures showing
how the shelves are made.
-clark
Date: Mon, 24 Aug 1998
Believe it or not, scratches on front elements
don't degrade quality as much as you might think.
A very large scratch, or a "sandpapered" area,
will have the effect of increasing light
scattering and flare and softening the image, but
a relatively inconspicuous scratch will result in
an unnoticable amount of flare and will not
degrade the image in any measurable or observable
way.
In the olden days, pros would go right ahead and
shoot with lenses that had large cracks all the
way across, as long as the glass hadn't gone out
of alignment. It used to be common practice to
fill a scratch or gouge with black paint. This
reduced light transmission, and the effective
f-stop, by an insignificant amount and solved the
flare problem.
Still, a scratch is a valid reason to pay a lot
less for a lens. Also, I don't know how you feel,
but I really wouldn't want to shoot with a
conspicuously scratched lens. Even knowing the
photos would not be affected, I'd still feel like
it said the wrong things about me and my
standards. But, then, I touch up paint chips on
camera bodies, too.
Scratches on rear elements are a different story.
They can significantly alter the light path and
will almost invariably degrade the image.
David Foy
From: dcline@silcom.com (Richard Cline)
Date: Fri, 25 Sep 1998
The silicon oxide/dioxide is applied by vapor deposition immediately after
the aluminum deposition. There are some differences in the process. The
aluminum is commonly evaporated by a tungsten filiment. Silicon dioxide is
evaporated from heating by an electron beam. There are a variety of other
elements that are evaporated to form antireflection coatings or special
purpose filters.
Dick
[Ed. note: a proper lens hood is recommended for reducing flare, but most
lens hoods are too wimpy to get the job done with tele-lenses, and the
wrong angle coverage or vignetting with many wide angles - sigh...]
From: Chris Buechner chrisbu@genasys.com.au
Yep, and a proper lens hood should be the same length as the focal
lenght of the lens. ie a 200mm lems sould have a 20cm long lenshood.
That is not always true of the lenshoods supplied with the lenses, which
is why many sports photographers make their own, normally of black
cardbord.
See ya
Date: Wed, 30 Sep 1998
I had this happen toa few 35mm lenses. You can try opening it wide and
placing it in direct sunlight for a day. If the fungus does not
disappear, or is heavy to start with, get the TLR to a pro and have it
cleaned. The longer the fungus stays in the lens, the more chance you
have of actually having it dissolve your glass. The by product (or
excrement for lack of a better term) of fungus is something that will
eat away the lens coating first, then will begin to etch the glass
itself. I had to have elements replaced in one lens and had to trash
another because of this. Don't wait.
Peter K
Date: Sat, 03 Oct 1998
At 06:46 PM 10/4/98 +0930, you wrote:
If the chip is where I think it is filling it with flat paint is about
the best fix. It shouldn't have much effect on lens performance especially
when thelens is stopped down a bit. Without the paint it may cause some
flare. Check to make sure the lens is properly seated in the mount and
look for any signs that the chip was caused by dropping. Probably it will
be just fine.
----
Date: Sun, 4 Oct 1998
I have a 3.5 Planar from one of the last 197x 3.5Fs. I mounted it on a
Copal shutter and use it with a Baby Graflex. That lens has a 4mm gouge in
the center of the front element and unless I'm shooting into the light
source it's tack sharp and flare free!! I got the lens from a repair guy
in Rhode Island who had it for 20 years. He replaced it in 1979 and said
the camera was almost new then. I'll try to post a serial # for Marc. In
my experience (which is not as great as most contributors here in RUG
land) the rear elements are much more sensative to manifesting problems.
regards-
Date: Mon, 05 Oct 1998
the only thing I can think of is the front lens group has come loose
(unscrewed a turn or two). Same thing happened to my 50mm. Take your
finger and give the lens a couple turns.
Date: Tue, 6 Oct 1998
There should be a locking ring around the glass. This sometimes vibrates
loose.
Turning the glass probably wont do anything because it just seats and is then
locked down by the ring. A special wrench is needed to really tighten it
safely, but finger tight may help. If you don't see this ring, btw, then you
have a CF lens and it's masked by the engraved ring.
Hope this helps a bit.
Simon.
Date: Fri, 16 Oct 1998
Wilf Lee wrote:
I know what you mean, Wilf. Unless you are shooting for yourself or have
a remarkable client, most folks do not appreciate the stark reality of
the high resolution lenses in their portaits. Blasting in lots of front
light can help (not the friendliest environment in which to work,
however), as does N+1 or N+2 exposure and the appropriate
underdevelopment.
Along these lines, I've had some good luck with an old prewar automat
(uncoated tessar) and a 'cord III (coated xenar) used at wide aperture.
As you point out, these lenses are really best suited to situational
portraits and you do have to be careful about getting too close and
perspective distortion.
Eric Goldstein
rec.photo.equipment.35mm
You can also get them at a gun store, usefull for preventing rust in a
safe.
Doug.
JWMALAHY wrote:
rec.photo.equipment.35mm
Here in Japan, where the problem is severe, they sell "dry cabinets" which
have doors which seal like refrigerator doors (air-tight skirting with
magnetic catches), and which include a small electric dehumidifier and a
hygrometer in the front to check the relative humidity. This works great for
me--and the relative humidity in my house during the dangerous summer months
hovers around 80%. You can make something that will work using a cooler box
(like you take along to the lake filled with beer on ice). The trick is to
find the dessicant. Again, here in Japan, they sell silica gel in big
plastic containers that will absorb between 300-450 ml of water. It's been
awhile since I've been in the states, but I would be surprised if there
wasn't some kind of drying agents available--to keep closets or clothes
boxes dry or whatever. If you put one or two of these in an airtight box
with your lenses (yes minus lens caps and filters, so that the air can
circulate), this should keep the humidity down enough to inhibit fungus
growth, even in the dark. A cheap hygrometer dropped into the box will let
you monitor the relative humidity--it should be below 50% to reliably stop
fungus growth. Less than 40% is not recommended as it can dry out the
leather used on camera bodies, but then who has leather on camera bodies
anymore? My equipment, including bellows live in 30-50% humidities and have
not developed fungus, or had problems with drying out.
Good luck, and get it done soon,
Toby Marshall
rec.photo.equipment.35mm
The simple and cheap solution (a dry cabinet? ouch!) is a set of ziploc bags
in which you stick a silica gel pouch with the lens. That's all there is to
it.
rec.photo.equipment.35mm
Also check out your local West Marine or Boat U.S. store.
They carry a number of different items intended to help keep storage
lockers on boats dry.
T.O.
From: hargravep@NOSPAMmala.bc.ca (Powell Hargrave)
As posted by myself and others earlier in this thread.
DO NOT POLISH A SCRATCH OUT OF A LENS!
I repeat:
It will remove the lens coating.
Even a bad scratch will have little effect on the image produced by
the lens.
It will not make it less sharp. All it will do is reduce the contrast
produced.
Leave it alone unless you are sure it is degrading the image. If you
are sure the scratch is ruining the image contrast fill the scratch
with something black to stop it from refracting scattered light onto
the image.
Use a lens hood and/or keep a UV/Skylight filter over the lens to
protect it.
From Medium Format Digest:
Usually a tiny mark, nick or scratch will have no perceivable
effect on image quality. A coating of dust or marks all over the
surface of the glass, like you might get by cleaning your lens
with a shirt tail, apparently will (although I have not tested
this myself).
I used to have the classic Nikon brand lens caps with the little
clutches on my 35mm SLR lenses but everytime I would go out on one
of my assignments with all of these lenses bouncing around in my
bag, these little caps would just pop off. Thus I got a tiny nick
in the front of one of my lenses. It is one of the lenses I use A
LOT (the 35mm f2) but have noticed no change in performance due to
the nick. Now I use the screw on metal caps --- they take longer
to remove but do not pop off by themselves.
Probably this tiny mark will not affect your lenses performance.
Unfortunately, such marks drastically decrease the resale value.
From: "John R" JRiegle@worldnet.att.net
Sounds like you have a scratched element. I am finding that many lenses
today are sold with defects. Here is an example of what I've found:
Brand new Nikon 80-200/2.8 ED AF D: 1-1/2" long scratch on the the front of
the 2nd element from the lens front. The scratch was very faint, could only
be noticed when light reflected off it at a certain angle. Front lens
coating seemed to have a faint mottling in areas. Also noticed black specs
on an element near the rear (inside). No noticeable affect on performance,
but too many defects IMO.
Vivitar 24mm/2.8: very faint scratch that arcs across the rear element
edge to edge. The raised ring around the edge of the element makes me
believe that it would be nearly impossible for this to happen (edge to
edge) from handling or cleaning, but was a manufacturing defect. Again
only noticable with a penlight and doesn't seem to affect image quality.
Pentax IQ835? point and shoot. When holding the shutter open on Bulb mode,
I noticed that the lens was rather filthy internally and it again had the
'ol faint scratch. IMO, a bit dirty for me but it (again) didn't seem to
affect the pictures.
Tokina 400/5.6 ATX AF for Canon: Had a small orange speck on the rear side
of the front element; otherwise very clean. The other Tokina 400/5.6 I got
in K mount was perfectly clean - an exception to the rule!
John
rec.photo.equipment.35mm
I noticed dust inside of my 105 f2.8D micro-nikkor just as I was getting
ready to sell it. Not wanting to sell somebody a lens with dust inside, I
sent it to Nikon for a cleaning. It cost me $130 for the cleaning!! It
is my opinion that the new autofocus lenses are not as well sealed against
dust as the old manual focus lenses were, at least I never noticed dust in
a manual focus lens before. Maybe I was just lucky.
Billy Gorum
rec.photo.equipment.35mm
I wish the prime lenses really were sealed better. Otherwise, my 105 f2.5
would not have enough dust in it to plant flowers! MF and prime lenses have
the same problem as AF and zooms. ALL lenses get dust in them. Fortunately,
it really does not hurt anything unless it is REALLY REALLY bad.
Sam A.
From: Guoming Shou shou@odysseus.ai.uiuc.edu
Baby wrote:
It's actually quite common in Nikkors. One annoying character besides
their superb optical quality. The first time I found it I was really
upset. But now I just neglect it. Small amount of dust might affect
picture quality, but virtually you cannot find it.
If you are interested in how dirty the inner elements of a lens can be,
you need to look through it against some light source, say, a bulb. At
some angle, you'll see all the dust and marks on the coating. I bet you
won't find it easy to fall asleep that night. :)
(Surely if the dusts are large, or there are too many of them, you need
to negotiate with the dealer.)
Good luck!
Guoming
From: "Isaac H Crawford" eyes1@mindspring.com
The reason that Nikon lets this go through their QC is that IT MAKES NO
DIFFERENCE... You can believe that if there was any potential image
degredation, Nikon would not let it through. Even if they did get rid of it,
after a little use, you'd have it in there yourself...
From: "Michael A. Covington" covington@mindspring.com
Think about it -- how much dust will it take to affect a picture? Do you
mean loose dust or tiny bubbles suspended in the glass? High-quality
optical glass often has bubbles. Nikon may have decided they'd rather have
bubbles than have more chromatic aberration.
--
rec.photo.equipment.35mm
Good thinking. Astronomers do that when a telescope mirror has some
unavoidable bubbles or scratches. Paint them black so they don't reflect or
transmit light, and truck on!
--
Date: Sat, 07 Nov 1998
At 10:54 PM 11/6/98 -0600, you wrote:
Fungus which is not cleaned off glass fairly quickly can etch the glass
leaving pits. What you have may not be fungus, I've found several
Rolleicord IV's with what appears to be oil droplets on the inside surfaces
of the lens elements. To get this (or fungus) off the inside of the
viewing lens requires removing it and taking it apart. This requires
removing the front panel from the camera and also requires readjusting the
focus co-incidence after replacement. The taking lens is easier although
its hard to get the front cell off wihtout taking the front panel off. It
can be done. Usually the inside of the front cell, which consists of two
air-spaced lensesm, is sealed up well enough not to get dirty but the
surfaces facing the shutter can get coated with fungus or other slime.
They should be cleaned out. If you don't want to undertake this yourself
the camera should be sent to a competent repair person.
----
rec.photo.equipment.35mm
I recently purchased a Nikon 80-200 f/2.8D ED/IF lens from B&H.; Upon
inspection I noticed what looked like small dust particles upon several
of the inner lens elements. Even noticed what appeared to be a small
bubble within one of the pieces of glass itself! Is that normal to see
that an occasional peice of dust or flaw within a Nikon lens of this
calibur or am I expecting toooo much?
Jeff
rec.photo.equipment.35mm
Purchased a new 80-200F2.8 in July. Noticed some very small dust
particles in it just as I have in every new Nikkor I've ever purchased. I
cannot detect any degradation of image quality because of this. A friend
of mine who owns a camera repair shop noted that most all lens will have
some dust even when new no matter who makes them (even Canon). Also, one
touch zooms actually suck in dust as a vacuum is created inside the lens
as it is extended so dust accumulation and movement inside the lens is
virtually unavoidable.
rec.photo.equipment.large-format
Tracy Hamby h820@pe.net writes:
Maybe. The term refers to the alignment of glass elements in each cell,
and cell alignment. The centering is done at the factory when they finish
the edges of the elements, glue elements together, machine the cell mounts
and mount the glass. It is possible to create a centering problem by
dropping the lens and damaging the shutter, in which case the optical axis
of each cell is no longer in alignment with the other. If the lens isn't
sharp in the new shutter, the shutter may have been damaged. Alternatively
the spacing might be off, or there might be a fingerprint or residual oil
on the inner/outer cell surfaces.
For a quick check on shutter condition, place a sheet of glass on a stable
table and shim it with sheets of paper so it is level in every direction.
Place the lens on the glass sheet, and place another glass sheet over the
other cell, and check if it is parallel. If the shutter has been damaged,
it won't be, and Schneider will replace it. If it passes that test, then
check the front to rear cell spacing in the old and new shutter. You can
just measure the distances from the outer edges of the cells with a
machinist's caliper.
If you want to look for a centering problem directly, there are a couple
of approaches which require an improvised optical bench. If the lens is
focused on a small bulb filament covered with foil with a pinhole in it
(star image), and the lens is rotated, if the image moves around in a
small circle when viewed with a microscope, it is decentered. The degree
may/may not affect performance. If the image shows coma on axis, you have
a real centering problem. The direction and size will remain the same
across the field unlike common coma which runs out radially from the lens
axis. If the star image is placed off-axis and the lens is rotated, its
orientation will vary and size will increase/decrease with rotation.
Note that the image wander may not be present if more than one surface is
decentered permitting cancellation. However, decentration coma may still
be marked.
Another problem which will arise if the cells/groups/elements are off
axis, is that the plane of focus will no longer be perpendicular to the
lens axis - it will be tilted with the camera in "neutral".
If you can't sort out the problem (hopefully, its a fingerprint), Steve
Grimes might be able to resolve the problem and repair it.
Date: Tue, 01 Dec 1998
Greetings Fellow readers
The usual advice proffered to intending purchasers of Rollei TLR's includes
inspecting the Rolleiflex taking lens for edge separation or lens
delamination. Often the advice or inference seems to be to pass these
cameras by.
I am interested in hearing from list members just how critical this is, or
to what extent can edge separation be tolerated (eg 2mm or 3 or 4 ...all
around the circumference is OK/not OK) or if it is OK are there any
qualifiers (eg as long as not shooting at widest apertures into bright
light source etc). Is edge separation on the front doublet of a Rolleiflex
2.8/80mm E or F planar more or less cause for concern than edge separation
affecting the rear doublet of a Rolleiflex 3.5/75mm E or F planar?
The only posting that I've been able to find that specifically addresses
image quality suggested that the difference between a Rolleiflex having
edge separation (degree unspecified) and one without was "dramatic".
People on this list must be using cameras that have varying degrees of
separation. On my 2.8/80mm planar with 3-4 mm edge separation, as long as
I shoot at f5.6 and below and avoid strong lights either in the picture
area or outside it (ie sun) there doesn't appear to be a problem. If I
don't do this then blue flare highlights occur in the transparencies.
I'd be really interested in the experience of others.
Regards
rec.photo.equipment.35mm
While I am not a big fan of Sigma, this is not the problem only happens
to Sigma. Haze on inner elements does not necessary mean group separating.
The earliest stage of group separating shows some rainbow banding which
could be very difficult to detect. Even the best lenses from Zeiss or
many other manufacturers can have this problem. This could due to the
age of the lens, or caused by impact damages. In many cases, haze on
inner elements could be cleaned.
===========================================================
Date: Mon, 30 Nov 1998
At 09:12 AM 12/1/98 +0800, you wrote:
I've had only one Rollei with edge separation. It was on a f/3.5 Xenar on
a Rolleicord IV. This camera took perfectly sharp pictures, the equal of
two other Rolleis with the same type of lens. The separation was very
slight, perhaps less than a millimeter.
I have other old lenses with edge separation. Two are B&L; Tessars for
large format cameras. Both have some cemement degradation at the edges,
again not much. In both cases the lenses are perfectly sharp. Both must be
stopped down considerably simply because of the amount of uncorrected SA
and coma. At f/11 or smaller the edge separation has no effect whatever.
All of these lenses were cemented with Canada Balsam. Edge separation is
very common on old lenses cemented with this stuff. A worse problem occurs
with newer lenses cemented with synthetic cements. I have seen a couple of
Kodak Ektar lenses where the entire cement layer has developed an egg-shell
texture which noticably diffuses the image. I also have seen lenses where
the cement developed what look like large bubbles, actually areas of
separation throughout the surfaces. One of these was a late 1940's
Wollensak LF lens, the others were lenses from a Zeiss Contaflex. This
camera and its lenses looked as though it had been badly abused. It was
offered to me for $150 US with four lenses a couple of years ago. Perhaps I
should have bought it.
Cement problems are one reason its a good idea to take a flashlight along
when hunting for used lenses. Shining it through the lens will show up a
multitude fo troubles which may be hard to spot otherwise.
----
[Ed. note - even Hasselblad's Zeiss lenses, new in box, can come with
bubbles and defects - surprise!]
...
rec.photo.equipment.35mm
I find it interestingly inconsistent that you rightly regard a bit of dirt
on a lens as a non-issue, but a UV filter as an image degrader. Frankly
even if the presence of a high quality filter (Nikon, Canon, B+W,
Heliopan, etc.) degrades the image, however slightly, I think the use of
the filter to protect the front element is more than warranted except in
the case of throw away lenses. I think the changes to the image from the
presence of the filter are not measurable and I have seen tests that
conclude as such.
BTW, I own a 65 mm Rodenstock that I purchased for about $275 used
(instead of the normal $1000) because it met the ground with no
protection. I think the previous owner would have rather sacrificed a $75
B+W filter. Incidentally, the scratches are only noticeable when the lens
is pointed into the sun.
Cheers,
From: Brian Ellis beellis@gte.net
In the course of examining all of my 35 mm, medium format, and large
format lenses recently I've been dismayed to find that with several of
them, when you hold them at various angles to the light you see a bunch
of what look like tiny pin holes or other irregularly shaped blemishes
in the coating. The pin holes/blemishes have a purplish tinge to them.
The brand of lens doesn't seem to matter - it has happened on Nikon,
Pentax, and Schneider lenses. The same thing appears on a number of
skylight filters. Again, brand doesn't seem important. I've seen the
same thing on several B+W filters and on several Hoya filters. All of
the lenses and filters were purchased new within the last four years,
are kept in their respective backpacks or camera cases in my air
conditioned house, and some are also kept in lens cases made by the lens
manufacturer. They go outdoors roughly once every two weeks or so on the
average, never in extreme cold but in some heat and humidity since I
live in Florida. I would appreciate it if anyone could suggest what
might be going on and how to prevent it from continuing. I assume there
is no way to reverse what's already happened short of having the lenses
recoated but if by chance there is something that can be done I'd like
to know that too. I've seen references to storing lenses with silica gel
or something like that to absorb moisture but I've never thought it
necessary since the lenses spend 98% of their life in my air conditioned
house. I haven't noticed any ill effects in my photographs but the pin
holes certainly don't look very good and I'm sure would affect the lens'
value.
Thanks for any help anyone can give. Brian
From Nikon Digest:
- -------------------------
When I got my lens I checked it over very close. The demo model the store
was using already had brass appearing on the mounting ring. Theu brought
out another, and it has a scrathc in the FRONT element! Then out came the
only two other lenses they had, one had a LOT of dust and another had a
teensy bubble in the glass.
I grabbed the one with the teeny buble. Why? A lot of folks do not know
how lenses are made, nor what the bubbles mean. In the olden days the
glass would cure as it was formed, and any bubbles appearing would be signs
of perfection, showing that the lens has been cured and is it the top of
perfection. Some old Leica owners would ONLY buy lenses with one or two
bubbles in them! After a bit bubbles became passe, so a person would be
hired to pop the bubbles, their only job in the manufacturing process.
A couple teeny bubbles are fine, and wil have NO effect on the final image.
Mine has one small bubble. I am more concerned about the rear element
primarily, then the front element, then lens feel and noise, then dust.
Bubbles are no concern unless they are in the center of the lens and you
can still see then when stopped down to f/8 or more.
My 80-200AFS is so fun I shoot at aperture priority and shoot wide open to
get the most out of it!
Robert in Redlands
From: kfritch@aol.com (KFritch)
I've tried several things with varying degrees of success.
1. The first, and most basic is take standard lens cleaner and tissues
and give the lens a good cleaning. Make sure you store the lens in a dry
place with little humidity. Fungus likes moisture and humidity. Use
dessicant packages if you can and remember to use the lens case and end
caps. You can substitute a zip loc bag for the lens case. Believe it or
not, that will often clear up the problem without recourse to anything
fancy.
2. For stubborn, recurrent cases, I have used a dilute solution of mildew
remover (mildew is a fungus) followed by a cleaning in normal lens
solution to remove any mildew remover and then a quikck zap with a UV
lamp. I'm never sure what mildew remover is going to do to the coating,
but so far the lenses that I've done this with have survived. I have,
howver mostly done this on older optics where loss is a c'est la vie sort
of thing.
From: dickburk@ix.netcom.com (Richard Knoppow)
Stafford@wind.winona.msus.edu (John J Stafford) wrote:
The fungus should be removable with normal lens cleaning fluid. A
small amount of Clorox will disinfect areas it touches and should not
harm glass surfaces from a one time use. It is possible that exposure
to direct sunlight may also kill off some types of fungus, its worth a
try.
Fungus can etch both glass and coatings, its important to get it off
as soon as you can.
What ever infected the equipment showing the fungus may also have
infected other equipment stored in the same place. Typically fungus
gets started were there is excessive humidity.
I don't know a real preventive other than storage in a dry
environment but reportedly some thymol crystals in the container will
prevent fungus growth.
---
From: "xa" xa@nospamxa.net
1. They're not very bad.
2. They're worse in flare conditions
3. They're not worth fixing
4. They will reduce the resale value of the lens substantially.
This is how some lenses end up being life long friends to
their owners.
-xa
Brian Dinse wrote
From: "Szymon Zi�tkiewicz" szymon@amedec.amg.gda.pl
I was always led to believe that silica gel was VERY toxic !
Hi!
I was considering the use of silica - gel for keeping my equipment dry -
and I will try this summer.
And I can't agree with this statement about toxicity. I'm a biotechnology
student, so I hope I have some chemical and some medical knowledge.
So: so-called "silica-gel" , as the name tells us, is a partially - hydrated
amorphic silicon dioxide SiO2 (silica), in phase of gel. It' s the same
chemical compound that normal sand. Only difference is that this silica has
microscopic pores, so it can adsorb many substances, and become hydrated.
The more pores, the more adsorbtion.
It is stained by addition of cobalt chloride (CoCl2). This substance changes
its colour in presence of water. When silica is saturated with water from
moisture, CoCl2 becomes to catch water and change colour from blue to pink.
Both processes are reversible, so heating leads to regeneration of this
mixture.
SiO2 is obviously not toxic - vide beaches. It is regarded, only in crystal
form (not gel) as "potentially carcinogenic agent" (at least in Poland), but
only when one is to inhale large amounts of crystalline dust - like
stonecutting or something like that. Non-dust crystaline silica is that most
of Earth is made of, and can be harmful only when falling down on someone
from height in a large bag:-)
There is different situation with cobalt chloride: this substance, as other
soluble cobalt salts, IS toxic.
But there is only small amount of it in silica - gel. Possibly there are
other coloured water -sensitive compounds added.
And most of it is inside granules, so it will not penetrate outside gel
easily.
Definitely, You are not to eat silica-gel. I think one have to eat really a
lot of it to become poisoned with cobalt (anyway, better not to try). But
You are not to be affraid of accidental contact with this substance,
inhaling dust or so. If kept in closed container (with pores, of course),
not used to thicken soup and not given to children - it's safe.
Well, I hope it's not too long, as the subject is not exactly
photographical. I hope I explained the question.
Happy (dry) shooting and best pictures
-Szymon Zietkiewicz
PS. BTW, as we are talking about silicon compound; did You know, that food
that has "E900" additive contains poly(dimethyl)siloxane - a compound used
for breast implants that caused all that mess about them? I conduct some
experiments about it's toxicity at my Pharmacy Dept.
From: dickburk@ix.netcom.com (Richard Knoppow)
....
The shutter is worth what you paid for the lens.
---
Date: Wed, 26 May 1999
you wrote:
The edges of the elements are painted with a matt black paint to prevent
internal reflections from them. Often this paint flakes off in older
lenses. The effect is like bubbles around the periphery of the lens. How
much effect this has on flare depends on how bad it is and the design of
the lens. It has little effect on many lenses when they are stopped down.
You can tell by visual inspection from the film side of the lens.
Fixing this requires disassembly of the lens and removal of the elements
from the mount. This is simple for some lenses and a real pain for others.
Generally the rear elements of small Tessar type lenses are in "burnished"
or "spun" mounts which have to be cut apart to get the glass out. Front
cells usually can be opened more easily.
Different manufacturers used different paints for the purpose so one can
find lots of Schneider lenses of the fifties and sixties with this problem
but some much older lenses of other makes with no paint separation.
If you want to attempt repainting lens edges the best stuff to use is
Krylon Ultra-Flat Black, available in spray cans. You may want to spray
some into a small container and use it with a brush. Its also the best
stuff for retouching anti-reflective surfaces generally in cameras.
The can is about $8 US the last I looked.
----
From Nikon Mailing List:
In Digests #180, 183... there was a discussion on filter systems for
ultra-wide angle Nikkors ( ie 20mm 2.8AF)...as well as the Cokin P series
and Lee system, there is also a new Cokin system available, with filter ring
adapters up to 122mm, making it the most viable for big glass..The filters
themselves are made of optical glass, unlike the older conventional "A" and
"P" series..and the Graduated Neutral Density is a true ND, unlike the
earlier series which were actually a Graduated Gray. I haven't been able to
see them in store yet, but I called the Minolta rep. ( Canadian distributors
for Cokin ) and they have them in stock.
Also, In regards to a low-budget way to aquire a dessicant for using your
cameras in humid environments, may I suggest your local piano store? When
pianos are shipped, they are often packed with quite large packs of silica
gel which are often discarded after receiving....The first camera store I
worked at was next to a piano store, they always had some to spare for our
customers if we asked...
Cheers,
From Nikon Mailing List:
In light of the current discussion on humidity and camera equipment, I
thought that I would share my solution to the problem.
I contacted Brad Wolk at Dessicare, Inc. (1-800-446-6650) (
www.dessicare.com ) and he suggested that I use their prepackaged packs of
silica gel and Humidity Indicating Cards. Each gel pack adsorbs 35% of
their weight in moisture. I bought a couple of hundred 3-gram gel packs.
Humidity Indicating Cards (HIC) turn from blue to pink depending upon the
humidity level of a given environment. Their 30%-50% HIC cards are
packaged 125 cards per can and each can costs about $30.00. I bought one
can of those.
I place each lens or body in a Zip-lock freezer bag, along with a gel pack
and a HIC card. I replace each gel pack and HIC card when the humidity
card indicates that it is over 40%. During the most humid summer months, I
have to replace each gel pack and HIC card about once every two weeks.
This system has been working very well for me.
A fellow list member mentioned that he uses a Radio Shack humidity
indicator. I feel that this would work best if you have all of your lenses
and bodies in one container. However, with my system, I have each lens and
body packaged individually. If I want to take a lens that I may or may not
use, I just put it in my camera bag, enclosed in its Zip-lock bag. If I
need it, I take it out of the Zip-lock and if I don't it is still protected
and I return it to its place at home.
Anyone who is worried about humidity affecting their equipment and who
doesn't live in a true tropical environment should consider silica gel
packs and HIC cards.
Happy shooting!
John Butler
From: fmitman@aol.com (Fmitman)
Hi, I am an owner of a camera store. Every now and then we receive a lens
from a manufacturer which displays a small bubble in one element of the
lens. Usually the bubble is in the front element. I contacted a
technician at Minolta about how it affects image quality. I was told
unless the bubble is quite large or is located on the rear element there
is no noticible effect on image quality. These lenses have passed
inspection because image quality in not affected. Did you notice any
specific problems with any images? I expect not. Don't worry your lens
is fine. You may, however, have a problem if you want to sell it on the
secondary market. People who do not know image quality is not affected by
this aberation will be less likely to pay top dollar. I hope I have
helped.
Sincerely, Frank Mitman, Allentown PA
From: "Michael Liczbanski" nospam@nospam.net
A minor nick on the FRONT element will most likely not affect the image
quality, but I wouldn't accept any imperfections on a brand new lens,
premium or not. If your dealer tells you that this is normal, they are full
of shit and I wouldn't deal with them at all. I have bought my share of
Canon lenses, and have never seen any visible flaws in coating on any brand
new Canon lens, L or not.
A general note: One reasons that mail order places keep their prices low is
that some of them sell "factory seconds", customer returns, "demos", etc.
and try to pass it as brand new, first quality equipment. I'm not trying to
say that your lens is an intentional "factory second"... I doubt that Canon
would let a flawed lens (esp. the L) out of the door...But it could have
been a demo, or a return, or a rental lens that got cleaned and
repackaged...
B&H; is considered a good dealer, so I believe that this is just a
"booboo"...They should accept the return and supply you a god lens no
questions asked.
Michael
Michael wrote in message ...
From: "John R" jriegle@worldnet.att.net
My new Nikon 80-200/2.8ED AF D had a very fine scratch visible on the
element just behind the front element. The coating on the front element was
not smooth in some areas and there were a couple black specs on the inside
of the rear element. The lens performed fine, but I thought these defects to
be excessive.
JCR
Michael wrote in message ...
From the popular Rollei Mailing List:
From: Richard Knoppow dickburk@ix.netcom.com
At 03:40 PM 8/18/99 -0800, you wrote:
Bubbles were once an indication of "Jena" glass, specifically Dense
Barium Crown glass which has a high melting temperature. So, the idea was
if your lens had a couple of small bubbles it was an expensive lens.
Modern glass making techniques have eliminated the bubbles. Actually the
presence or absense of bubbles is meaningless in terms of lens performance
other than a lot of bubbles will cause some diffusion. A _lot_ of bubbles
or big bubbles in a lens suggest the maker didn't have very good QC or was
too cheap to reject the glass. One or a couple of small ones are without
optical effect and meaningless.
----
Date: Thu, 19 Aug 1999
i have a triple convertible symmar with maybe 20 bubbles in the front
element. still sharp as a tack. i wonder how much bubbliness would make a
lens get rejected in those days at JSK
Richard Knoppow wrote:
From: Dave Munroe davem@notformail.hp.com
Michael wrote:
Buying a new lens is similar to buying a new car: you expect
it to be perfect and without scratches.
That said, am I correct in thinking that what you have is just a
small flake of the coating material missing rather than an actual
gouge or nick in the lens?
Here is what I say in my _Hasselblad Lens Guide_: "A spot or two
on the coating isn't that serious. Why? Because an entirely
uncoated lens transmits about 95% of the light and about 5% is
dispersed as flare. A single layer of coating reduces the flare
to roughly 1% and a multilayer coating (usually six layers) reduces
the flare to less than 0.5% (less than half of one percent). So,
a relatively small spot on a coated or multicoated lens would
contribute only an extremely small fraction of 1% towards flare
or loss of contrast."
Ultimately, the decision is yours to keep it or exchange it, but
if it's just a flaking off of a bit coating material, then even
an expensive optical lab would be hard pressed to detect any
difference between it and a "perfect" lens.
-Dave
[Ed. note: vibration can loosen lens screws and rings...]
Dan,
I'd second that, a friend just returned from Iceland. He cycles round there
each summer for weeks at a time, this year he took his Hassy for the first
time along with his Leica.
After a few weeks he pulled it out of the bag to find it had a strange
sound, a clunky rattle. He took the lens off to find the rear element
rolling around inside the body! It didn't 'jam', but the lens was certainly
'not mounted properly'!
best regards,
Jem
.....
[Ed. note: another unexpected source for silica gel supplies cheap?]
The dumb part: Someone inadvertently sees them and wonders if I have
a medical problem that (say) might interfere with shooting a 6 hour
wedding & reception (grin), and this is my backup supply.
Tom
From: spam-abuse@worldnet.att.net (Tom)
Alex -
Its not such an elementary question as you might think.
The optical definition of contrast (in anything) is:
(I_max - I_min) / (I_max + I_min),
where the I's are the intensities of light in different regions of
space, for example, the light intensities coming off of the maximum
and minimum reflectivity regions of a bar target. As defined this
way, contrast can take any value from zero to unity.
For a lens, a very well known test is to use a bar target (of some
specified contrast), illuminated by white light, and form the ratio of
the contrast of the image formed by the lens to the contrast of the
bar target, and plot this ratio as a function of the spacing of the
lines in the bar target.
This effectively gives you the "contrast of the lens" for large
subjects, small subjects, and everything in between - exactly what you
asked (perhaps a bit more - grin), It turns out that this is
(essentially) a well known quantity in optics - the MTF or "Modulation
Transfer Function" of the lens.
A "perfect" lens will not degrade the object's contrast at all, and
the contrast of the image that it produces will equal that of the
object.
For all lenses, when the spacing of the lines in the bar target is
sufficiently small, the lens won't be able to resolve the bars and
will simply average the bright and dark bars and produce an image
contrast of zero.
A "low contrast" lens is one where the image contrast starts becoming
degraded at unusually large spacings of the lines in the bar target,
not just at very small spacings.
Hope this helps,
Tom
rec.photo.equipment.35mm
If the dust particles are out of focus, they are on the bottom side,
inside the mirror chamber, and can be (gently) blown off. If they
particles are sharply focused, they are between the screen and the prism.
Best thing to do is to leave them alone. They are not in the film path and
do absolutely no harm to your images.
EJKowalski
rec.photo.equipment.large-format
I had an old zeiss ikonta with fungus on the lens, and decided to try
cleaning it, as it was at best a $40.00 camera.
I took the elements out and soaked them overnight in hydrogen peroxide and
amonia, and then cleaned with a lens cloth. The fungus is gon, and the glass
remains in amazingly good shape. The only lasting effect is that the lens
coating is gone wherever the fungus was.
It improved the lens tremendously, but did not restore it to perfect
condition.
On old, uncoated lenses, I would think the chances of a full restoration
would be reasonably good. Definately worth trying, considering how
cheaply a fungus-bitten lens can be bought.
rec.photo.equipment.35mm
On Sun, 19 Dec 1999 13:13:06 GMT, smitbret@my-deja.com wrote:
You can buy the stuff at Walmart for a few bucks per pound
in the crafts section. It's used for drying flowers.
~~~~~~~~~~~~~~~~
rec.photo.equipment.35mm
On Sun, 19 Dec 1999 19:29:13 -0600, "Sarawoot Chittratanawat"
I put some in a coffee filter and close it with a twist-tie.
Richard
rec.photo.equipment.35mm
I store my camera gear in airtight containers with various drying-agents:
- Silica Gel. I found that at camera stores silica gel packets were absurdly
overpriced at 3 or 4 little bags for $10-$12. Absurd! At arts and crafts
stores, you can buy "Flower Drying Crystals", which is none other than 100%
silica gel. A half-gallon size can of Flower Drying Crystals costs around
$6. That's enough to make a few hundred small little cloth bags or packets.
(The biggest hassle is to make the little bags.)
- Absorbant clay. Some camera dealers sell a set of four little packets for
$10-$12, but those are not a good value. The absorbant clay is none other
than the very same material at the clay that you can buy as kitty litter!
Or, at auto parts stores, they sell the exact same stuff to absorb oil. A 25
pound bag of kitty litter is only a $3 or $4. I put coarse kitty litter in
brand-new infants or childrens socks, tie up the socks, and voila!
NOTE: In either case, be very careful about dust from either the silica gel
or the absorbant clay. You will want to make sturdy packets that do not leak
or let out gel or clay dust! The last thing you will want is for dust to get
into your camera gear!
Another enemy of camera gear is mildew. Along with homemade packets of
silica gel or absorbant clay, I enclose cedar shavings. It won't necessarily
prevent mildew, but it does make a "hostile" environment for mildew. For a
few dollars, you can buy a huge bag of cedar shavings at Kmart, Walmart, or
any pet store. I stuff the cedar shavings into mens or boys white gym
socks--brand NEW ones only, please--and enclose cedar sockies in with the
gear in zip-lock storage bags. And all of that goes into sealed water tight
plastic boxes.
TIP: Do not store camera gear in leather cases! If there's any one part that
is more apt to attract mildew, it's leather, leather, leather! Store your
leather bags and cases in separate sealed bags and containers.
rec.photo.equipment.35mm
What I finally did was purchase 5 gallon painters bucket and for $10 there
is an airtight attachment you can hammer in place. I then wrap my
equipment in a large zip lock bag with gel in the bag and also gel in the
bucket. So far, the gel in the bucket has not turned pink nor the ones in
the bag
From: C. Downs
...
This is from John S. Carroll
"Spherical Aberration. Spherical aberration is the inability of a lens
having spherical surfaces to focus rays passing through the center and
edges of the lens at the same point. If rays passing through the edges
of the lens focus closer to the lens than those passing near the axis,
then the spherical aberration is considered positive; if the marginal
ray falls beyond the paraxial focus, it is considered negative.
No single lens can be completely corrected for spherical aberration
except by shaping its surfaces to some form other than spherical;
usually paraboloidal. However, in systems of several lenses, it is
possible to combine lenses having negative and positive spherical
aberration in such a way that they cancel each other out. Such a
system will not be entirely free from spherical aberration, though;
when the marginal and paraxial rays are brought to the same focus, it
is possible that rays from some intermediate zone will still fail to
come into the same plane. This condition is known as "zonal spherical"
aberration and is sometimes more serious than a simple undercorrection
of primary spherical aberration.
Ordinary spherical aberration tends to causc the out-of-focus rays to
sur-round the sharply focused points with a small halo. The cfTect on
the image as a whole is to cover the entire image area with a haze of
scattered and out-of-focus light. This tends to reduce the contrast of
the image, but because the scattered light is much less bright than
the sharply focused rays, it does not tend to damage the image
definition very much. The effect is most visible with large aperture
lenses on reflex cameras; the residual spherical aberration is seen as
a haze that is most severe at full aperture, tending to disappear as
the lens is stopped down.
This haze, containing as it does little of the available light, can
often be minimized by the simple expedient of underexposing slightly.
This is what is done in the case of the ordi,mry box camera; the
single lenses used in these cameras have a considerable amount of
spherical aberration, but since most box cameras are used on the verge
of underexposure anyway, it has little effect on the image. Obviously,
the use of faster-than-usual films in a box camera can seriously
degrade the quality of the image.
When a lens is corrected to bring the extreme marginal ray to the same
focus as the paraxial one, then the residual error is usually in the
form of a zone of spherical aberration at about 0.7 of lull aperture.
If, though, the 0.7 ray is brought to the same focus as the paraxial
ray, then there are two zones of residual spherical aberration, one at
the margin, the other about halfway be-tween the axis and the 0.70
point. These zones are opposite in direction and usually are only
about half as serious as the single zone of residual spherical
aberration resulting from a union of the marginal and paraxial rays.
Since the zonal spherical aberration tends to cause a focus shift as
the lens is stopped down, it is evidently desirable to reduce its
effect to a practical minimum in this manner. This is especially
important in the case of single-lens reflexes with automatic
diaphragms, where focusing is always done wide open, and the lens
is stopped down at the instant of exposure.
The use of paraboloidal curves to eliminate spherical aberration has
been tried in a few very expensive lenses. Because of the great cost
of grinding these special curves, it is not likely that any great use
will be made of them in ordinary camera lenses, Asphcric curves of
this type can he used quite easily and inexpensb?ely in projection
systems, however, in the condenser lenses, which focus the light on
the film or slide. In such projectors, spherical aberra-tion in the
condenser system produces a serious unevenness of illumination on the
screen. But since the condenser is not expected 10 produce a sharp
inage (it is only required to focus the lamp filament in or near the
projection lens), high optical quality is not required. Usually,
simple molded and fireLpolished lenses arc used in condenser systems,
and it is easy enough to mold such lenses into a roughly paraholoidal
shape. Often this reduces a condenser system to a single lens.
Coma. Unlike spherical aberration, coma appears only in off-axis image
points. The marginal rays have a different focal length from the
paraxial rays, and since focal length determines the size of the
image, points near the margins ale spread out into a fan-shaped
pattern by failure of the marginal and paraxial rays to intersect.
This pattern is generally somewhat comet-shaped, from which the
aberration takes its name.
Coma differs from spherical aberration in another way; most of the
light is scattered into the tail of the patch, rather than into the
sharply focused point.
This makes coma very visible even in small amounts. The usual effect
of coma is to cause all image points near the edges of the field to
blur outward; the effect Is exceedingly unpleasant, giving the
impression that the image is flying apart. Thus coma must be reduced
to the minimum in any lens which is to be considered we1 I-corrected.
Luckily, the correction of coma is not difficult; it is done in much
the samc way as the correction of spherical aberration, by combining
two lenses having opposite coma tendencies. It is quite possible to
correct both coma and spherical aberration with the same pair of
lenses (though some zonal residuals will necessarily remain), and a
lens corrected for both spherical aberration and coma as called
'aplanatic."
From: kahheng@pacific.net.sg (K H Tan)
Clay
Try Windex (or any similar window cleaner with ammonia).
Use gentle pressure with a ball of cotton.
If I am not wrong, the mixture used in pro service labs to clean fungus is
50% ethyl alcohol and 50% ammonia (not sure what concentration).
Years ago, I had lenses that had serious fungus issues. When they got back
from the shop, some of the coating had gone (had to see really, they just
look like see through specks) but the lens performance did not seen to
suffer.
Windex is a very good DIY liquid to use. I once bought a lens covered in a
lot of grit and grime. After vacuuming away all the loose dirt, Windex
restored the glass to pristine. Not too shabby I'd say.
Tan
Date: Thu, 2 Dec 1999
In the talk about lens separation, it was mentioned that bubbles sometimes
appeared in glass as a lens defect. My shooter is in fact a 3.5E with a
very small bubble in one of the rear elements, towards the edge. Doesn't
*seem* to affect image quality in any way. I remember being told that
bubbles in early glass used to be taken as a sign of quality; forget
why...
Anyway, has anyone else seen this in a 'fifties Rollei TLR? Is it true
that it has no effect?
Doug
From NikonMF Mailing List:
I had a 300mm f/4.5 which also got dust inside it. I took it in for
cleaning and the repairman suggested I not waste my money cleaning it. I
had it cleaned anyways. There was absolutely no difference before or
after cleaning. He was right. Cleaning was a waste of money.
From Nikon Mailing List:
At 02:38 PM 02/06/2000 -0600, you wrote:
I just had a 70-210 Zoom repaired by Nikon for fungus on the inside of the
rear lens.
They classified it a a class "C" repair, charged $140, and made some
repair to the Zoom mechanism as well (I hadn't noticed anything wrong with
it).
They have to take the lens apart, and reassemble, realign and columnate
the optics.
You should probably plan on adding this much $ to the eventual cost of the
lens you are looking at.
- -Gary
Date: 18 Jan 2000
Since the glass itself is out-of-focus for the film image, the scratch
will only matter if it scatters light to cause flair of image fogging. If
the scratch can be filled with a little black ink, it will not scatter
light, and you would find no effect on image quality. Maybe you should go
for it
EJKowalski
From Rollei Mailing List:
At 09:24 AM 2/13/2000 -0000, steven arterberry wrote:
Interestingly, this seems to be primarily a US West Coast phenomenon. We
went over this in great detail some years back on the LUG, and it appears
to be far more common among California and Washington-state lenses than in
the Eastern US. I don't know why. From my personal experience, it is
rather rare in the US Middle Atlantic area.
But, yes, all older lenses, regardless of make, are subject to gassing
from the lubricants used in the era, and this can lead to fogging, which
is generally quite easy to clean. Whether common or rare, it is a
condition which should be noted and which ought to be corrected before
permanent damage results. As I will, in general, send any used lens I
purchase to John Van Stelten for a CLA before I put it to use, it has
never been a major issue with me.
Marc
From Leica Mailing List:
Be advised that you should view any older Leica lens through a bright
light source at wide open aperture to determine the degree of fogging. It
is likely to have some. I understand that this resulted from the type of
lubricant employed by Leitz.
From Rollei Mailing List:
...
This is a pretty common effect with all lenses. I am not sure of the
source of the haze, it may be from the anti-reflection paint inside lens
cells, or from lubricant. In any case, it comes off with ordinary lens
cleaner. This haze seems to be nearly universal in sealed cells of lenses
of some age. I think one reason some older lenses have a reputation for
low contrast is more due to this haze than to lack of coatings or design.
The internal haze can absolutely destroy contrast.
AFAIK, Leica lenses are not too difficult to get apart to clean. Pay
attention to how the lens comes apart and put everything back as it came
out. Don't worry about de-centering. Centering of elements in a mount are
determined by the construction of the mount and the glass will be
automatically centered if the reassembly is done carefully making sure the
glass is seated before tightening.
Inspecting lenses with a flashlight as described here is a very good
practice. It will show up not only haze but evidence of flaking paint and
blemishes on the glass.
----
From Rollei Mailing List:
You know I had always been told that the acid in fingerprints could etch
them into glass. I always avoided fingerprints on lenses and glass slide
mounts for this reason. A couple of years back I mentioned this to a lens
designer and he said it was total nonsense. Do you know of any references
on this?
Bob
From Rollei Mailing List:
Under the loupe the fingerprints look superficial enough, but I'm no
eggs-pert. How do you tell whether it's superficial or etched?
Saliva is similarly nasty, as I noticed when I once spittled on a
slide while blowing off dust (dumb idea) as I was framing it. Left
a permanent spot which ate itself right into the film.
So drooling over a lens probably yields similarly disastrous
results. Happened to my MX once but I cleaned up ASAP. Now I
know why they lock the Rolleis up in glass cases at fairs;
there's a lot of drooling going on in there. :^)
--
From Rollei Mailing List:
......
I've seen fingerprints etched into coatings especially. They are
probably
more suseptible than glass. Optical glass varies all over the place in its
sensitivity to moisture and alkalies and acids. Some types of glass are
somwhat soluable in water and will be etched if stored in a very moist
place for a long time.
I can only refer you to manufacturers of optical glass. There are three
or four big ones.
----
Date: Mon, 08 Nov 1999
Bogdan Karasek bkarasek@videotron.ca wrote:
Its the cement separating a little. I dont know what causes the tiny
bubbles to form but it seems fairly common even for lenses cemented
with synthetic cement. Unless they seem to be causing an undue amount
of scattering they likely will not have much effect on the image.
You can probably get a good idea of how much light they are
scattering by lookin through the cut out corners of the ground glass,
or simply shining a strong light through the lens and seeing how much
bounces off. I would bet not much. I don't think its fungus. Fungus
has to start from some point of infection and that is usually at an
edge for a cemented surface. On surfaces exposed to air fungus can
look like little round gray spots or like a spider web. Fungus is bad
news because it gives off a substance which erodes the glass surface.
Sometimes exposure to very high moisture conditions will also result
in pitting of surfaces even when there is no fungus. I don't think
that has happened here.
---
From Hasselblad Mailing List:
.....
There are a couple of things to watch for if you buy an older C lens.
I've seen 3 or 4 that had an internal element separation. You can see
this by looking into the front of the lens an seeing a ragged colored
(usually blue) pattern around the circumference of the glass. It's easy
to miss if you've never seen it. A separation will reduce the value of
the lens by about $200 - $300. They can be fixed for about $300. I was
able to get a great deal on a 250mm with a bad separation. I took it
apart, separated the elements in my thermal chamber at work, cleaned
them and sent them to S.K. Grimes for recementing. I was out of pocket
about $70 and 3 hours work and now I have a very nice lens. I don't
recommend this to the faint of heart though.
The shutters are often slow and the depth of field preview hard to
engage, but these can be fixed.
Jim
Date: Fri, 5 Nov 1999
JJayT jjayt@aol.com wrote
My view would be that in normal shooting conditions, these marks make not
one iota of difference. The problems may come when shooting in difficult
conditions - like into the Sun. I suspect the marks would cause more
tendency for the lens to flare. Careful management, and a good lens hood
should help though. If they are significantly cheaper, and it means that
you can buy the lens, then I see no harm at all. If you think about it,
people often put cheapish filters over their lenses, smear them in
petroleum jelly, deliberately put scratched plastic for effects etc etc.
They don't worry, so I wouldn't either. I have a very tiny speck of dust
on the "inside" of the rear element on one of my lenses. I cannot tell
that it is there on any shots whatsoever! It bugged the hell out of me
that it was there, but doesn't affect the picture, so I've grown to live
with it!
Simon
Date: Mon, 8 Nov 1999
If scratches on a lens are deep enough to cause flare, there's a simple
cure. With a clean damp cloth, *gently* work a small amount of black
poster paint (the ready mixed type that comes in small jars) into the
scratches. Leave for a few minutes to dry and then even more gently,
polish off the surplus with a clean dry cloth. Black won't flare and if
the scratched area is small enough it should have no detrimental effects
on lens quality. Poster paint is water soluble and so can be removed any
time in the future with a wet cloth.
Regards,
From Leica Mailing List:
tedgrant@home.com writes:
When this kind of topic....."field curvature" comes up, may I ask
those
of you whom are knowlegeable and can readily identify what to look for
in a photograph and where this "lens character" can be seen. Please
post a description of what to look for and why it can be a bug-a-boo in
some pictures and mean nothing in others?
Field curvature is the lens' inability to focus all points of a plane
(such as a flat wall) on the film plane. This is usually manifested as
either the center or corners being in sharp focus, but not the two
together. This is not the same thing as a lens with decreasing resolution
away from the image center, where in that case no amount of focusing will
sharpen the corners. A lens with poor corner definition can have
substantial field curvature and it won't matter because the corners are
always soft, whereas a lens with superb overall resolving power but strong
field curvature will show the effects more obviously.
Why it means more in some pictures than others: 1. If you aren't focusing
a single, frame-filling flat-plane subject parallel on all axes to the
film plane, you won't see field curvature unless it is extraordinarily
severe (this is why so-called "flat-field" lenses are important mostly for
copy work and projection of glass-mounted slides). 2. Stopping down for
more DOF will reduce the effects of field curvature. Again, you can see
why a flat-field lens would be particularly useful in macro copy work,
such as photographing postage stamps (flat, full-frame subject, very
little DOF). Of all the "aberrations" a lens can have, field curvature
(unless it's quite severe) would be the one I'd worry least about. The
2-element 400 and 560mm Telyts (such as for the VISO and R-series), as
most achromats, exhibit quite high field curvature. But these lenses
aren't normally used for flat subjects. Wildlife or sports subjects
(central subject in focus, blurred background)would not be hampered by the
field curvature.
Hope this helps!
[Ed. note: even Hasselblad lenses are not immune to paint flaking
etc. ;-)]
Date: Sun, 24 Oct 1999
Logan McMinn mcminn@mail.idt.net wrote:
It will make very little difference if it is as small an area as
you indicate (0.5mm). The major change will be a little less light
through the lens, but not enough loss to be equal to even a small fraction
of an f-stop. There will also be a tiny bit of light scattered instead of
being focussed, but again, not enough to make a difference.
Somewhat.
Likely. How fast is anybody's guess.
The un-gluing part is the hardest. The glue is still holding 99%
of the surfaces together. I just successfully un-glued a lens, but it was
separated over about 50%. I used hot water from a tap in the kitchen to
warm the lens up from one side. When the glue finally let go, there was a
sharp "SNAP". I still had to soak the lens in alcohol and carefully pry
around the edges to get the two pieces completely apart.
Fargo, 1-800-359-2878, sells a lens cement, part # 81190. It
requires a UV light source to cure it. Most dentists use a similar UV
curing cement for tooth fillings and they have a handy UV source. If you
do get the lens elements apart, and if you manage to clean all the old
cement off, you might be able to get a friendly dentist to cure your
cement for you. It only takes a minute with the proper source.
It would be really cheap to repair it if you do the job yourself.
The cement is only $4.00. If you screw it up, just replace it. Getting
somebody professional to do the job is likely to be the most expensive
route.
Find a junk lens to practice on first. Wait until the good lens
gets a lot worse off before you work on it.
Jim
From Nikon MF Mailing List:
This is the optical version with the large rear element, as opposed to the
early pre-AI version, which has a comparatively small rear element.
If the lens elements are cemented together, there is no air, or gas of any
kind between the elements. Elements which are not cemented together have
regular air between them.
Nitrogen, or any other gas, or a vacuum between the elements would require
that the lens is sealed. This might be easy for simple lens designs such
as the 50/1.4, but in lenses where groups of element moving relative to
each other (IF, rear focus, zooms, CRC... ) it would be almost impossible.
Also, sealed gas between the elements would expand and contract with
temperature changes, which would put pressure on the lens, and might bend
the elements out shape.
Some lenses have a reputation for collecting dust. The AF 85/1.8 is bad
because the rear focus design sucks a lot of air (and dust) over the rear
elements while focusing. The inside of lenses barrels are blackened to
prevent reflections. Sometimes the paint starts to flake off old lenses,
causing dust on the lens.
As for fungus (if that is what is in your lens) then it is better to clean
it out. Fungus will eat away at the lens coating, and will eventually etch
the glass. It won't affect picture quality unless it affects a large area
of glass. Fungus also kills resale value -if that is any concern to you.
Roland
Date: Wed, 15 Mar 2000
While nobody likes crud in or on a lens, it happens, and an amazing amount
needs to be there before the image is seriously degraded. Recently I
placed a 3/4 inch strip of electrical tape across the center of a lens to
try an old-fashioned focusing technique. I was amazed at how little the
image changed!
Basically, like rust, dust never sleeps. Since lenses are not
hermetically sealed, dust, moisture and spores get inside. I'm sure one
of the others can speak of particular instances where extreme dust can be
a problem.
John
Date: 15 Mar 2000
I know on Pentax 67 lenses, focusing the lens turns the helical which
almost creates a vacuum which can ( and does ) suck tiny amounts of
atmospheric dust inside. Many times, a well aimed blast of canned air can
work wonders -OR- can actually put MORE dust on internal lenses !
Keep your lenses capped and stored inside an air tight container ( WITH
SILICA ) when not in use....
Date: Fri, 18 Jun 1999
Steve wrote:
you just observed chromatic aberration of your lens. This optical flaw,
which is very common even for modern lenses, manifests itself by
reddish, greenish, purplish or bluish halos around bright spots in the
image, or where there are strong gradients from dark to bright. It is
caused by the inability of the colours to be focused precisely at the
same spot on the film. This error cannot be abated by stopping down.
Expensive long lenses incorporate special glass (ED, fluorite) to reduce
the chromatic errors to a minimum. This is necessary because these
errors increase with focal length and with bigger aperture of the lens.
regards
From Rollei Mailing List;
sean, you can do this yourself. buy from an art store an india ink pen or
a bottle of india ink and carefully apply the ink to the chip. cover it
well, especially along the edges where most flare is probable. also read
this for more info on lens issues:
Camera cleaning, restauration and maintenance
Sean McTigue wrote:
From Rollei Mailing List;
you wrote:
Is this visible at the edge of the lens? Sometimes the anti-reflection
paint on the element edges starts to flake. It often looks like bubbles at
the edge.
The cure is simply repainting the edge with a suitable paint. It seems
more likely to me that this is the problem rather than a chip on an inner
surface, unless the lens has been disassembled in the past for some reason
and damaged. Its possible to chip an element by forcing it into the cell,
the clearances are practically nil.
On Rolleiflexes getting the cells out of the shutter requires some
disassembly of the camera. The work should be done by someone skilled in
Rollei repair as well as knowledgible about the lens. Harry Fleenor or Bob
Maxwell come to mind. John van Stelten at Focal Point does all sorts of
lens repair and recoating. I don't know whether he is a good Rollei tech
as
well, its worth contacting him.
focalpt@ecentral.com
FWIW the best currently available paint for this is Krylon Ultra-Flat
Black, available in spray cans at hardware stores. The best of all paints
was a product called Black Velvet made by 3M, it was discontinued some
years ago. The Krylon works fine but if the surface is going to be sealed
the paint should be baked out at 130F for half an hour to prevent its
outgassing after assembly.
----
From Rollei Mailing List;
OK, my friend and colleague Roger Hicks knows more about lenses than
any four others I know combined. Here is what he says about this
question of "hot" lenses.
Bob
From Hasselblad Mailing List;
[Austin] I have not had such a problem as you describe, but I have a
problem with Hasselblad and the way they handle this type of 'repair'.
I have a lense that was sent to Hasselblad to be cleaned. They stated the
lense has a piece of 'material' IN the coating they could not get out, and
if I wanted it fixed, it would cost $800 to replace the rear element.
They also said that it must have been there when the lense was originally
coated, and they have no other explanation for it.
If it was there from day one, that would be a defect in material and
workmanship, and just because someone didn't notice it while it was under
warranty (in fact, they should have noticed it and repaired it...), I
believe they should have taken the initiative to repair it at their
expense. That would be an honorable thing to do, and I am quite surprised
they didn't even offer that as a solution. These are expensive pieces of
equipment, and people buy Hasselblad based on reputation for exceptional
equipment, and this type of problem, and their response, is not what I
would have expected if they want my continued business and support.
I don't know how old your lense is, or if it was exposed to any harsh
environments, but I think the same thing should apply...if the coating is
just flaking off...it sounds to me like a defect in material, and they
possibly should have just offered to repair it for you at their expense.
They could also just take the lense apart, and replace the baffle that is
flaking, couldn't they?
I have yet to write them about my 'situation', and am curious is anyone
has written them with similar venue and what their response was...
-------------------------------------------------
I understand that there are very few 30 F-Distagon Fisheye lens in use,
but I have a question which someone in the group may be able to answer.
I recently sent a 30mm lens to Hasselblad in NJ asking for an estimate to
re-coat the black baffeling in the interior portion of the lens. The
baffeling or black coating has begun flaking and it appears that it will
get worse without repair. Anyway, Hasselblad USA wrote back and said that
they would have to send the lens to Sweden for such an estimate. What I
can't understand is why they can't just tell me what it will cost to
re-coat or re-surface this black baffeling. I can't believe that this is
a first time situation for them. They must have had other such repairs
work and should be able to give my a "ball-park" estimate. Has anyone had
a similar problem with the 30mm F-Distagon or other baffeling problems
with other Hasselblad lenses?
Thanks.
rec.photo.equipment.medium-format
It is possible that you got one of those Mamiya lenses with defects
(lens element separation) on the 6 or 7. It would have rendered the
images fairly soft. But if you get a regular then it would have been
another story. Eventhough I have complained about this kind of defects
that unfortunately happens once in a while, I have sold my Hassy and
lenses and own a MF6 and a M7.
--
From Contax Mailng List:
Depends on how big a scratch, where it is, and which lens.
If on the front or rear element, then that element can be
replaced if the scratch is big and centrally located. If the
scratch is small and toward the edge, generally it can be
ignored so long as you are not using the lens wide open. As
you stop down light from the edges ceases to be used to form
the image.
The "old timer's" trick was to fill the scratch with black
paint to cut down on its effect.
Bob
....
From Nikon Mailing List:
While we are on the subject of quality, I would like
to share my thoughts on this issue. Somehow I feel
that the QC standards of Nikon has fallen a bit.
Lately, I have seen bubbles and grinding marks on
their newer lenses, namely AF-S lenses. And I am not
even talking about sample variations between lenses.
What is more worrying is that Nikon feels that these
grinding marks on the lens elements are normal and
common! In a written reply, they actually said that
such marks are within their tolerances.
To be honest, I can't recall seeing grinding marks on
any of their older lenses. Somehow, these marks are
now acceptable because they don't affect the final
image. Kinda of like buying a scratched Mercedes Benz
if you asked me. The car still moves, does it not?
Please understand where I am coming from. I am not
trying to bash Nikon for the sake of it. This is just
my reaction to some of the things that has been
happening lately.
Alan
....
From Contax Mailing List:
ABSOLUTELY NO!!!!!!!!!!!!
Do not use those eyeglass sheets on cameras!
Most contain a silicon "lubricant" which is OK on eyeglasses
but can ruin photographic surfaces like mirrors.
Use ONLY lens cleaning fluid.
Bob
From Nikon Mailing List:
This is a common problem with much older lenses and
recently with some AF-S lenses.
With regards to picture taking, there should not be
any problems at all. Your main problem starts when you
try to sell this lens. Depending on how "serious" is
the problem, you may not get a good price when you
trade in.
As far as Nikon is concerned, they have what they
classify as their "factory tolerance". Too many
bubbles on one element(how many is anybody's guess)
and they will "fix" it for you. Otherwise, they will
simply tell you that there is nothing wrong with the
lens.
Suggest you make a trip to Shriro(the agent) and ask
them for their feedback. No harm finding out.
Regards,
Alan
- --- Eugene Phua phuaweh@cyberway.com.sg wrote:
From Nikon Mailing List:
Dear Guys,
I think I've just discovered a small air bubble on the 2nd last
element of my lens. It is a rather small bubble, abt 1mm in size. Will tt
affect picture quality? Will Nikon replace the lens for such defects?
Eugene.
From Leica Mailing List:
Since this thread started back a while ago, I started to notice glass, in
its many incarnations, and it seems that ALL glass has bubbles in it to
some degree- I have seen it in window glass, bottles, glasses (drinking
type) and just about any place you look. Exceptions seem to be the float
type plate glass, and perhaps it is raise to a high enough temperature
that it becomes fluid enough that bubbles can escape. Optical glass,
however, is not made in huge batched, but in relatively small quantities,
and according to the Brittannica, is cooked for a fairly long time to make
sure it is thoroughly homogenous, and then it is cooled slowly so as to
minimize areas of stress within the glass. The bubbles pretty much should
not effect the image as they only occlude the rays passing through that
point, and being optically dense, would not scatter light to contribute to
flare. The area they occlude would be insignificant in calculating open
aperture- unless they were so many that they blocked a statistically
significant amount of light. For all practical purposes, small bubbles, or
even small specks of dust will mot harm the image; it would take something
like a smear of grease or fingerprint oil- or someother diffuse
obstruction to introduce the flare and loss of detail.
For me, it has become less important to get every little tiny speck of
dust off the lens, as it intrudes on my looking for interesting subjuects!
So- quit looking so much into the front of your cameras looking for fly
spots and dingleberries- and spend more time looking through the
viewfinder!! :o)
Dan
From Pentax Mailing List:
If I recall correctly from lens school, aspherics were intended
to correct chromatic abberations ( colour fringing). The are of
more use in the longer focal lengths that they first showed up
in. I really don't think that aspheric elements are all that
useful in shorter lenses. Might be another case of marketing in
action.
William Robb
From Nikon MF Mailing List:
> Bjorn Rorslett commented on the Nikkor AF-S 17-35mm f/2.8D at
> http://www.foto.no/nikon/lens_zoom.html
> There, he noted sample variations that suffered from "optical decentering"
> and "focus shift." I have written to him for more information but have
> not recieved a response. Can anyone on the list explain what these terms
> mean? How can I test my lens to see if it suffers from these problems?
Optical decentering is where elements in a lens are not perfectly aligned.
Alignment is relatively easy to achieve in lens where all the lens
elements are contained in a single unit. Decentering is rarely a problem
in simple prime lenses such as the 50/1.4. Lenses with CRC, IF, rear focus
and zooms have groups of lenses which move relative to each other
(floating elements) when the lens is focused or zoomed. It is very
difficult to allow movement between these groups and maintain perfect
alignment. Optical decentering is very common in cheap zooms. It will show
up on brick-wall tests where one half of the frame has different sharpness
from the other half.
I guess focus shift is where the focus shifts sligthly when the lens is
zoomed.
Bjorn will probably reply in time - I have communicated with him in the
past, and he often replies to questions on photo.net.
Roland
From: David Littlewood david@demon.co.uk
Dave Herzstein dherzstein@juno.com writes
Good advice. The effect, if any, on resolution should be unnoticeable if
the damaged area is small compared to the total area of the front
element. The most serious damage to lens resolution is that caused by
thousands of tiny scratches all over the lens, which is the common
(tragic) result of inept cleaning attempts. One ding amounting to say 1%
of the surface will normally be fine, though it won't do a lot for the
resale value...
There is one nasty exception to this - if the damage is exactly in the
centre of the lens, then the effect on image quality could dramatically
increase at small apertures. Think about it, a 5 sq mm ding on a 50mm
f/1.8 - say 2500 sq mm - front element affects about 0.2% of the image
wide open. At f/16, the camera is only using the central 30 sq mm or so.
If the ding happens to be slap in the middle of that, the effect will be
much greater.
The only way to be sure is to test, but do it on a tripod, and use the
whole aperture range.
--
From: carbon_dragon@yahoo.com
"...it remains Leitz policy not to design lenses
purely to achieve high resolution of flat two dimensional
test charts, but deliberately to leave intact a modest
degree of aberration and curvature of field to improve the
rendition of three dimensional subjects." Collecting and
Using Classic Cameras, Ivor Matanle, Thames and Hudson
1986.
Is that statement true? Does Leica intentionally design
lenses this way?
A lot of people have claimed on this newsgroup that Leica
lenses have a particular look. If this statement is true,
perhaps this look is explainable to the satisfaction of the
more skeptical among us.
Date: Mon, 10 Jul 2000
The degree of correction for spherical aberration may be an important
element in lens design; perhaps it's what gives, say, the Contax 85/1.4
and the Pentax FA*85/1.4 lenses their nice "look" ;^)
Regarding design choices to achieve a "Leica look", you might consider
the following from Erwin Putz at
http://www.imx.nl/photosite/leica/courses/course.html
"Current Leica thinking in lens design is to opt for a high contrast and
a high resolution, and many of their lenses show clearly the advantages
of this approach . . . Older lenses had a lower contrast and thus a
lower resolution, not because of particular design goals, but because
the state of the art at those decades did not allow for better imagery."
And:
"When testing a lens on an optical bench, we look at the plane of focus
to assess the image quality. But is is very easy to defocus slightly
before and after the plane of focus. The tester then can simulate the
out of focus areas quite well by looking at the image when defocusing in
small increments. Any optical design program can accomplish this. . . "
And, finally:
"Optical performance is not to be confused with the perception of an
image . . . When talking about image perception we walk into a totally
different realm of lens evaluation. Here personal opinions abound and
every opinion is as good as any other."
(FWIW, I might not recognize a "Leica glow" if it bit me. Even if I
could mount those lenses on my range finder, I don't think the "glow"
would illuminate much more than the middle of the frame :( )
Brian
Colyn wrote:
From: jess4203@aol.com (Jess4203)
John:
I have a reference for Paul Ebel, who advertised lens recementing @ $55 in
1998
Shutterbug. His address is:
W230 Terrace Street
Phone 1-715-778-4372
I guess from Europe, there is a country code to add rather than the "1."
John van Stelten, in Arizona, used to be the only person who advertised
this service, but I don't see him listed in what I've looked through. He
is very experienced if you find his ad, but not cheap. Schneider has a
repair facility in NY which advertises repair of large format lenses, but
I don't know if that means recementing.
Sommers Optical has a website for various UV cure optical cements, and I
think there is a FAQ there on how to do it. I think the Angulon is more
difficult than other lenses because at least one element is not the same
diameter as the others. Usually, when they are all the same diameter, one
uses a set of machinist's "V" blocks to get everything lined up. If you
are thinking of using a spring loaded jig, maybe you have already thought
this through. If the lens is not really useable, you could try heating it
in the oven, slowly, in the jig to see if it will un-separate. I tried
this once and succeeded only in boiling the balsam and making the lens
completely cloudy, but I think I went too high with the temp. I would try
150 F first and then try higher increments.
Steve Grimes is an obvious choice, too, comes very highly recommended. I
think he has some pages on recementing on his site, too.
I'm not sure what you are using the 120 for -- I wouldn't spend too much
on it if there are other lenses which would replace it for you -- there is
the 135 WF Ektar for 4x5, and a slew of inexpensive old 90's. The 120
Angulon probably has more coverage than any of these, however. Maybe
Richard Knowpow will join in here on this, he has some expertise in lens
recementing.
HTH,
From: "Brian S. Boothman" bboothman@unitedmold.com
I have made several large achromatic lenses from raw glass blanks and
have found that oiling my lenses rather than cementing them yealds
superior performance and allows for maintenance. If you can separate the
lens by SLOWLY heating it to about 240F and remove the cement residue with
acetone you should be able to re assemble it using a scant drop of mineral
oil. You may need to clean and re oil them in a few years as the mineral
oil can oxidize.
John Dancke wrote:
From: dickburk@ix.netcom.com (Richard Knoppow)
....
Both Steve Grimes and John van Stelten offer recementing services.
The cost may be more than the lens is worth.
Its not too hard to cement leneses yourself but the Angulon has a
couple of problems. The big one is that the elements are not the same
size. Mostly, a lens can be positioned for cementing by clamping its
edges, which are very precisely concentric to the optical axis.
outside element of the Angulon is much larger than the two other
elements, so it can't be clamped in this simple way.
The other problem may be the type of mounting. Often single
component lenses are mounted with a "spun" or burnished mount. There
is no threaded retaining ring or cap which can be removed. The
burnished down back of the cell must be pried up or machined off and a
threaded cap made to replace it. This machine work makes re-cementing
this type of lens expensive.
The age of the lens would give you some clue as to the type of
cement used, lenses made before about 1950 will be cemented with
Canada Balsam, later lenses with a synthetic cement. Schneider has a
complete serial number chart on their web site for dating lenses.
Canada balsam usually starts crystalizing at the edges showing up as
a ring of yellowish brown. It can also turn milky, but that is rare.
Synthetic cement can show the interference rings you mention or
large "bubbles" in between the elements.
Lenses cemented with Canada Balsam are much easier to separate than
those with synthetic cements. Canada Balsam will become liquid if the
lens is gently heated to around 150F, the temperature depending on the
type of Balsam used. The usual recommendation is to heat the elements
gently on a frying pan but I've found that hot water works well. Put
the lens in the water and then heat it to avoid thermally shocking the
glass. The Balsam will liquify well below the boiling point of water.
Synthetic cement requires a great deal more heat, the amount
depending of the type of cement.
Summers Optical sells a decementing solvent for the particular type
of cement they sell, it probably works on older types of cement. The
lens is heated in this stuff. It is relatively safer than heating in
an oven although there is a certain amount of fracturing even with
this method due to thermal shock.
Both cement and solvent must be shipped as hazardous materials, at
least in the US, which considerably increases the price. International
shipping may be prohibitive.
Canada Balsam can be used for re-cementing, but its getting hard to
find and is actually harder to use than the newer type cements.
Summers has a primer on cementing on their web site.
If you choose to try this I recommend the Summers type M-62 cement.
This is a two component cement cured by heating to 140F. The cement
stays liquid for many hours at room temperature so there is no hurry
in working with it. It pre-cures in 20 minutes and fully cures in
about an hour at 140F. The temperature is not very critical. The
cement continues to cure at room temperature so if the oven cure isn't
quite full it doesn't matter, the cement will be fully cured in a
couple of days anyway. It can't be overcured.
They make a room temperature curing cement but I like the extra
margin of time the normal cement gives you.
I've cemented lenses successfully with this stuff, it was much
easier to work with than Balsam, which I have also used.
Check with the folks below about cost before getting into cementing
it yourself.
From Leica Mailing List:
Is colour fringing in out-of-focus areas the unavoidable artifact of
internal focusing was the question and one Lugger noted that this is BS,
without any argumentation. The topic, however, can not be discarded so
lightly. On the assumption that the original person used the lens in near
focus distance, as this is where internal focusing is designed to improve
optical performance, the question than becomes: is there a longitudinal
chromatic error that can be increased in the unsharpness area, due to the
close focusing. As chromatic errors are not related to magnification in a
lens and only to the (apo)chromatic correction, it is doubtful that this
phenomenon can be increased by internal focusing. When the angles the rays
of light make are quite large, higher order aberrations however might
introduce some longitudinal chromatic error and if the cams along which
the internal lens group moves are not adjusted properly there again is a
source of error. Theoretically all of these options are to be discarded
for this phenomenon and practically too there is nothing to support the
original assertion. It is however an interesting question and while the
straight answer is a plain NO, you need some reflection to bring the
arguments for this NO.
Erwin
Date: 29 Aug 2000
I used to own an old FC-65 (uncoated rear fluorite element). I bought it
from a fellow in the Houston area (nice and humid, reasonably close to the
ocean too). I don't know the specifics of how it was treated (but I could
guess...).
Anyways, the lens had obviously gotten stored while wet and with moisture
in the air gap space. A mottled film was present over about 40% of the
area. I expected that the fluorite had been etched by the moisture
(believing the common 'wisdom' about fluorite). However, the fluorite was
just fine and it was the non-multicoated front element's rear surface
that was affected. The fluorite was hazy, but cleaned up good as new (and
it was no problem to clean, no scratches from my careful cleaning).
Bob Luffel
Date: Tue, 12 Sep 2000
It is possible to not notice the marks. I purchased a lens for a Mamiya
C330 on Ebay a while back. It was supposed to be in perfect condition.
When I examined it I held it up to a light and it looked fine. I then used
a 12,000 CP flashlight shining back at me through the lens - there were
swirls on the rear element that you wouldn't believe ( a recessed element
no less). The seller took back the lens - no questions asked. From my
experience I believe that he honestly didn't see the marks - I missed them
at first myself.
From Hasselblad Mailing list:
In response to Peter. I have a SWC with a chip in the rear of the lens
although it was not me who reported seeing spots on his film. To the
contrary, I have not noticed the spot at all. It was treated by Larry
Litteral(camera technician) as you described. As a side, I am curious how
these chips happen in SWCs. The price of the lens should reflect the flaw
and if it seemed reasonable with that in consideration I would take some
test pictures and then evaluate the sale. I know I would sell mine a
reduced price commensurate with the lens condition just as if the front
element were scratched.
I think that should equal about $.02, too!
Russ
Date: Sat, 02 Dec 2000
My finding is that the rear element is critical. One smudge in the rear =
element, and you have a big loss of contrast. A fellow here on the list =
had an SWC with a chipped rear element, and reported gray spots in his =
final prints in a spot consistent with the chip. I've heard of filling =
chips in the front with India ink to cut down on flare. Myself, I just =
replaced my eyeglass lenses due to a chip right in a critical spot that =
was bothering me. Would I buy a lens with a chipped rear element? =
Probably not.
....
My $0.02,
Peter
From Hasselblad Mailing List:
My finding is that the rear element is critical. One smudge in the rear
element, and you have a big loss of contrast. A fellow here on the list
had an SWC with a chipped rear element, and reported gray spots in his
final prints in a spot consistent with the chip. I've heard of filling
chips in the front with India ink to cut down on flare. Myself, I just
replaced my eyeglass lenses due to a chip right in a critical spot that
was bothering me. Would I buy a lens with a chipped rear element?
Probably not.
....
My $0.02,
Peter
[Ed. note: lens bashing, anyone?... ]
As I said, "There isn't anything that someone, somewhere hasn't done. Does
this mean that you are going to do it? Most likely not." But, of course,
it will happen to someone, someday. While tens of millions of
photographers go on without having that epiphany.
You have to ask yourself if you had a flat filter in front of your lens,
would it have broken and gouged into the front element? Filters are thin
and flat and have no resistance to breaking as do lenses. Lenses are very
thick and usually have a radius that also helps thwart breakage. Look in
the LUG archives for one of Mike Johnston's more disgusting posts about
throwing a lens onto concrete repeatedly to watch it break. If I remember
correctly, the lens glass pretty much remained unscathed for a very long
period of repeated abuse. I could be remembering it incorrectly however.
But, of course, everyone must be true to their own beliefs.
Jim
From Hasselblad Mailing List:
If one does purchase a lens with a rear element chip, it's important to
know how much that chip effects the lens performance. For example, a chip
on the rear element but off on the edge of the glass may only affect the
lens when the aperture is wide open. A chip in the centre of the rear
element is going to be prone to flare at all f-stops.
I have a lens with a rear element chip off to one side. If I take the
magazine off the camera, lock the shutter open and look through the lens
from the rear, I can see when the chip is within the field of view at each
aperture stop. The lens I have has a chip that only affects the lens at
f/2.8 At f/4 the chip is no longer in the field of view, therefore, it
doesn't affect the performance of the lens.
In fact, I have used the lens at f/2.8 and have never noticed an increase
in flare. If I had the lens tested, it probably would statistically have
more flare at f/2.8, but I don't notice it with my eye.
There are chipped lenses out there that are a bargain if you know what to
look for.
From hasselblad Mailing LIst:
Thanks to everyone who responded to my question about the chips in
the 60mm chrome f/4.0 lens I was examining (it's not a 50mm, that was
a typo). The slides came out great, can hardly tell the difference
between it and my 80mm CT*, except for the wider angle of view. I
didn't check it in a wide variety of situations, such as heavy flare
conditions, but I felt good enough to get it anyway. I'll be using it
at weddings with a Lumedyne flash setup, and I did test it in a
studio, so I'm confident it will produce those Hasselblad sharp
images that I'm used to. Time will tell, but I do think Mark Rabiner
is right that slightly defective lenses can be a great buy, as long
as they are not too defective. The other nice thing is that when I'm
rushing around in a wedding I won't worry about this lens as much.
Unlike my 50mm, a CF FLE that I bought as demo for 2.5x this lens
cost, which I usually fret will get dropped or encounter some other
calamity.
Robert
From hasselblad mailing list:
In response to the discussion on chipped lenses, I have an 80 lens with
scratched front element and a large chip out of the rear element. So far
I have seen no abnormal image in the family portrait work we do - although
I usually shoot from 5.6 to 11 - most importantly this lens and the other
compromises I made got me into Hasselblad inexpensively, and it takes
great images.
What can be done to reduce the chance of flare in the rear element ? - one
store I went to suggested that you take a lighted candle, make it smoke
onto a smooth surface, then use a Q-tip to place the candleblack into the
chip. I haven't done it yet - has anyone else heard of this remedy?
Hugh Thompson
From Hasselblad Mailing List:
....
Wait until you get your tests back. Look for any aberrations in
fine detail in the center of the chromes like fine lines that should
be straight software or are displaced slightly or have a little more
flare that the rest of the shot and is highly localized.
In general, as far as nicks, dings, chips, and gouges in the glass:
the less, the better; the smaller, the better. Damage to the rear
element and in the center is more of a problem -- image-wise, than if
the same damage is at the edges.
Damage on the front element is less a problem than if it is on the
rear one. If the damage is at the extreme edges of the element,
either front or rear, and are tiny to moderate nicks, they will have
no effect on overall picture quality.
--
From: frederickl@aol.com (FrederickL)
Another quick test for your speed graphic and optar set up is to focus
(using a loupe) on a ruler which is oblique to your camera...maybe at 45
degrees or so. Focus carefully on a specific point on the ruler....say 6".
Expose using the lens wide open (you want to minimize the depth of field)
and then look at the ruler on the negative and see where the actual
sharpness is. With care you can replicate this for the center as well as
the corners. To speed things up, put enlarging paper in the holder (cut
to size) and process it... you'll have a paper 'negative', but you'll be
able to see the sharp areas very quickly. This will tell you if the
ground glass should be adjusted...and with some thought...which way it
needs to go. (oh, yes, with enlarging paper as 'film' start with an asa
rating of around 5 or 10 for figuring exposure)
It is critical that you'll need the camera on a sturdy tripod.
Should help you get a handle on what is going on.
Good Luck
From Rollei Mailing List;
you wrote:
More likely this is the result of the cement turning yellow. I don't
know what these lenses were cemented with. They are late enough to have
used a synthetic cement rather than Canada Balsam, but maybe not.
I have a similar lens (for an Exakta) which is quite clear. It
definitely is NOT from radioactivity.
Some lenses made with early Lanthanum glass, like the Kodak Aero-Ektar,
are slightly radioactive due to impurities in the glass. Later Lanthanum
glass is not radioactive. It is very common in post-WW-2 lenses. There
were a very few lenses made with Thorium glass, which is very radioactive,
but they were produced for special military purposes and I don't think any
were ever sold on the open market.
----
From Rollei Mailing List:
you wrote:
Or a green, or a cyan filter. What it does is limit the colors going
through the lens. Since some early lenses were not very well color color
corrected eliminating one end of the spectrum tends to make the lens
sharper. Most very old designs were achromitized (color corrected) for
orthochromatic film, which is not sensitive to red. A filter which cuts
out
red light (cyan) will help sharpen up these lenses if they show fringing.
Many lenses from even the wet plate era are actualy fairly well
achomatized because it was necessary to get the "chemical" focus (blue
light which exposed the film) and the "visual" focus to coincide.
There are two forms of color error or chromatic aberration, to use the
proper term, longitudinal and lateral, correcting one doesn't necessarily
correct the other.
Longitudinal color is a characteristic of glass, it comes from the same
variation in light bending with wavelength that causes prisms to project a
rainbow. It is effectively a difference in focal length of the lens for
different colors, i.e., the len focusses different colors at differences
from the lens. This effect is quite visible in a simple hand magnifier
when used to project an image.
In camera and other lenses it is corrected by using a combination of
positive and negative elements of different kinds of glass so that one
lens cancells out the chromatic error of the other without also cancelling
out the complete power of the lens. In a Rapid Rectilinear, and many other
simple lenses, the chromatic correction comes from cementing together a
positive and negative lens element of different kinds of glass.
Lateral color happens when the lens is corrected so that if focuses all
colors to the same point but the sizes of the images are not the same.
This results in color fringing. The simplest cure is to make the lens
symmetrical. Symmetry automatically cancells lateral color. In fact, the
cancellation is complete only when the entire optical system is
symmetrical, i.e., at 1:1, however, the cancellation remains at a high
order even when such a lens is used at infinity. Convertible lenses, such
as a Convertible Protar, are well corrected for lateral color when used in
combination, but often show some color fringing when the separate cells
are used alone. A filter helps to reduce this effect as would the use of
film with limited color sensitivity.
----
Date: Fri, 29 Dec 2000
winf_buechsenschuetz@my-deja.com
Sadly, the term "Apochromatic" has proven to be a strong marketing factor:
perhaps not all lenses that are labeled "apochromat" indeed are
"apochromats".
The standard meaning of "Apochromatic" (as was mentioned) is that at least
three colours have a common focal length. Better is allowed, worse not: a
lens that can only bring two colours to a common focus is called an
"Achromat"
There are indeed lenses that bring all colours (yes, *all*) to a common
focus: they are called "Superachromat" (Zeiss) or "Ultra-Achromat" (Asahi
Pentax). These lenses are corrected even beyond the visual (and "normal"
photographic) range, well into the IR-part of the spectrum.
The Zeiss UV-Sonnar even manages to bring all colours from UV (400 nm) to
IR (1000 nm) to a common focus.
All mirror optics are "superachromats". Unless they use refracting
lens elements as well, as most photographic ones do.
Forwarded from the Binocular List:
There is a new fungus treatment available from Zeiss Oberkochen. I have
no further ordering information.
Fungus Cleaning Agent "Fungusreiniger NEU"
Germicidal effect, not effective in cleaning. Dilute the agent with ethyl
alchohol, apply with cotton swab, allow it to act for one hour or more,
clean the surface using normal cleaning solution. Not poisonous but keep
away from food & avoid contact with skin. Can be ordered from Carl Zeiss
Oberkochen, dept. KuDi.
100ml bottle, INR 0117.362
___________________________________
Marc
msmall@roanoke.infi.net
Date: Sat, 13 Jan 2001
As atmospheric pressure goes up and down, lenses "breathe" the
ambient air in and out. With the air comes dust, so it's hard to find
a lens that's seen the outside of the factory for very long, that
doesn't have a bit of dust on the inside surfaces.
The manufacturers could make lenses that are completely sealed
with O-rings on the focus mechanism--Nikonos comes to mind--but
most aren't built thus and I doubt if we'd be willing to pay the cost.
Pierre Bellavance wrote:
[Ed. note: there are exceptions to most rules; the Hasselblad SWC is one
such for rear element scratches and gouges...]
Eric Armstrong wrote:
"[...] The pictures had what you might describe as "dark spots", which
were
quite large and, of course, very disturbing. [...] The camera, an SWC, was
thoroughly examined and some very small particles were found stuck onto
the
rear lens surface. [...] The design of the Biogon lens makes it
particularly
sensitive in this respect. Even a particle as small as 1/10 mm can cause
disturbing shading effects in the photograph, depending on the f/stop
used.
The smallest f/stop is the most critical."
Torbj�rn Eriksson, "Hasselblad" magazine, no. 73, december 1982, p. 30.
I think this means that painting the nick black, as some suggest, will not
remedy your problem.
[Ed. note: Mr. Meyers is a noted author of numerous photography
articles published in many major publications (Modern, Pop...)]
Another point I'd like to make is this: None of the well-known
lens testers and camera testers test over a period of time
where many rolls of film are used making actual pictures.
perhaps some lenses could develop (no pun intended) "play"
in the mount and focusing mechanism which would render sharpness
negatively (no pun intended). In otehr words, which cameras and
lenses perform equally as well when they are new and then used
for a few bricks of film (brick is 20 rolls at Kodak and 10 rolls
at Fuji). I mean Kodak bricks. Just another thought on the matter.
Ed
From Nikon Mailing List:
In my book, a lens has good (i.e. high) contrast if it transfers a
subject's contrast properties without much change onto the film. A lens
that has low contrast would turn original white and black into pale grey
and dark grey or something like that. Contrast and shrpness are related
but not the same; in MTF terminology I'd say that contrast is what's
measured at low line/mm settings, and sharpness what's measured at high
line/mm. And then to complicate things there's something called edge
contrast which is what Nikon uses to give a greater apparent sharpness to
their lenses... Maybe www.photodo.com can help you somewhat, though we all
take their results with a grain of salt.
Mark
From Nikon Mailing List;
Manis K. Banerjee wrote:
It's a good question, Manis. By which I mean, of course, that the answer
is a long one. :-)
In fact it's part of Owl's Very Long Answer to the question of how many
megapixels there are in a frame of 35mm: when you compare silver-halide
photography with digital photography, you have to think again about what
sharpness is.
But let's start with contrast. You've put it rather well in saying that
it's "where the shade and the highlight are clearly distinguished at the
borderline." A clearly defined line is sharp; a fuzzy line is not sharp.
As you say, contrast can be reduced if the film cannot render the line
clearly. It can also be reduced if the lens flares.
A lens does more than pass light through to the film. It absorbs a tiny
amount; and it reflects quite a bit. Consider a single-element lens with
two glass-to-air surfaces, the front and the back:
o Some of the light striking the front is reflected, and disappears
in the surrounding air.
o Most of the light striking the front is transmitted through both
front and back to reach the film in the right place.
o Some of the light transmitted through the front is reflected by the
back, goes out through the front again, and disappears in the
surrounding air.
o Some, only a very little, of the light transmitted through the
front is reflected by the back, then reflected again by the front,
and then transmitted through the back on a second attempt, to reach
the film ... in quite the wrong place.
(Would one of you at the back please give Piglet a poke? He's beginning
to snore.)
Flare can give rise to UFOs -- Unwanted Flaring Objects, which appear as
brightly coloured polygons on the picture -- but most flare is scattered.
It shows up as a reduction in contrast.
With a single element lens, things aren't too bad. But if you have a two
element lens, things are six times as bad:
o light can be reflected at the back of the front element and then
the front of the front element;
o and at the front of the back element, and the back of the front
element;
o and at the front of the back element, and at the front of the front
element;
o and at the back of the back element, then at any one of the three
surfaces it meets on its way out.
("Ouch," said Pooh. And even Kanga looked glassy-eyed.)
The cure for this lies in the multiple coatings that are now normal on
all lenses. They control the reflections, improve the contrast, and make
multi-element lenses possible.
"Has he finished now?" Eeyore asked Rabbit, almost hopefully, thinking
that, as Owl's lectures went, that one went quite quickly.
"No, that was only contrast," replied Rabbit. "He promised -- or
threatened, I'm not sure which -- to talk about sharpness as well."
Owl cleared his throat and continued:
To a silver-halide photographer, contrast is an important part of what
makes a picture sharp; and so is resolution. Picture A is seen as being
sharper than picture B if
(a) the detail in picture B is present in picture A, and the contrast
of that detail is higher, and
(b) there is detail in picture A that is not visible in picture B.
In this view, sharpness is the ability to show fine detail clearly, and
is a combination of resolution and sharpness.
When the TV engineers came on the scene, they realized that there was not
much they could do about resolution, but that it was possible to give
their customers a sharper picture by managing the contrast. For good or
ill, they gave us the modulation transfer function -- the MTF -- which
gives a measure of overall sharpness.
To many TV engineers, and to many digital photography enthusiasts, if the
detail in picture B is present in picture C, and the contrast of that
detail is higher -- but there is no new detail -- then picture C is not
only sharper than picture B, but it is sharper than picture A as well.
Aaargh!
To me, as a completely impartial dinosaur (I agree with those
palaeontologists who believe that the dinosaurs did not die out, but
evolved into owls), that seems like cheating. You can have a digital
photograph which appears supremely sharp because all the detail that is
there is high contrast, and any detail which cannot be high contrast is
not there.
Don't get me wrong. If you are taking pictures for a client, and
pictures like that are what meets the client's need, then take pictures
like that. Equally, digital image enhancement techniques -- which can
never add information missing from the original picture -- can make an
indecipherable picture clear, and that can be very useful.
Though I haven't yet worked out why this process is known as unsharp
masking.
"Has he finished now?" asked Eeyore again.
"I think so," said Kanga.
"Then we must be thankful for small mercies," said Eeyore. "We must be
thankful that he didn't give us this part of his Very Long Answer last
time. And that he hasn't given us more of it to-day."
"Well just one final point on sharpness," said Owl, "and that is that we
should outlaw the phrase 'tack sharp'. It means something different to
everyone who uses it, and is in danger of becoming a clich�. Tacks
should back to their niche of being used by grasshoppers to pick their
teeth while sitting on railroad tracks."
- --------------------------
From Nikon Mailing List:
"Manis K. Banerjee" wrote:
One lens can be sharp but can have low contrast. Another lens can be very
contrasty without being deemed sharp. Let's say we have 2 blown-up
images, one taken by the first lens and the other by the second lens. If
viewed at very close distances, the image taken with the sharper lens will
stand out as the resolution can be clearly seen. However, at normal
viewing distances (stand back a few feet) our eyes cannot resolve the fine
lines that a sharp lens provides but they can distinguish the differences
between dark and bright areas. Thus, the image taken with the contrastier
lens will *appear* sharper due to the "illusion" brought about by the
contrast. Throw in varying apertures of a lens and you'd have another
factor to fiddle with in deciding which lens is "sharper". In the end,
you would want a lens that is *BOTH* sharp and contrasty over a wide range
of apertures.
Just my 2 bits worth,
Ed Alban
From Rollei Mailing List;
Jon Hart wrote:
Weston was broke for much of his early years and was known to use old
rapid rectilinears bought from pawn shops for 5 bucks... often the front
elements were scratched to hell before they ever made it to the pawn shops
because the old timers were also known to be fond of cleaning lenses with
their neck ties...
May our photos look so good...
To paraphrase The Bard, the fault is not in our lenses, dear Brutus, but
in ourselves...
Happy Holidays,
Eric Goldstein
From Rollei Mailing List;
you wrote:
I'm not quite sure what you are after here.
Color correction of lenses usually means correction of the chromatic
aberration which is due to the variation of index of refraction with
wavelength of glass. The decamire system refers to filters for changing
the
color temperature of light. The dedamire system is a way of stating the
amount of shift so that it is constant with the color temperature, i.e.,
if
you know the decamire value of a filter you can calculate how much it
shift the color temperature.
Color temperature is a measure of the spectral balance of light. It
gives the "color" of the light in terms of the temperature in Kelvin
degrees of a true black-body radiator with equivalent output. This is
nearly correct for incandescent sources like Tungsten lamps, who's actual
temperature is close to that of the true black body source. It is only a
analogy for photo emissive sources like flourescent lamps or other broken
spectrum types.
The emulsion layers of color film are adjusted in speed so that the
color balance is "correct" visually for a given color of the source
illumination.
If the source is of another color the film will record the difference
since it does not have the ability that the eye does of adjusting
according to the source. Filters can be used so that the effective color
temperature of the light striking the film is correct.
Color negative film can be balanced in printing to some extent to
correct for the source color, however, if you think about what is gong on
its evident that there will be some compromise to the matching of the
three emulsions if very much correction is done.
Some lenses are designed with some attention to the color transmission
of the lens. Lenses for motion picture use are often matched in color
transmission so shots made with different lenses will look the same. This
is done partly by coating choice. Multiple layer coatings are really band
pass filters, their exact transmission can be adjusted to some extent.
Also, for single coated lenses, the transmission can be flattened out
somewhat by staggering the peak color for the coatings on various
surfaces.
There is some variation in the color transmission of optical glass, but,
for the most part, its pretty flat through the visual range.
The correction of chromatic aberration is done by combining positive and
negative elements with the appropriate partial dispersions. The idea is
that the dispersion will be cancelled while leaving some of the lens
power. The choice of glass used in the design is critical. Modern glass
types offer high index, low dispersion types, and some low index, high
dispersion types which, when combined, result in very good correction of
the chromatic aberrations.
There are two forms of chromatic, longitudinal, where the lens has a
focal length which varies with color, i.e., it focuses light of different
colors at different distances. The second form is lateral chromatic
aberration, also called chromatic difference in magnification. This is
where the image for all colors focuses at essentially the same point, but
the size of the image varies with color. Symmetry is one cure for lateral
color. So, lenses like the Dagor have little lateral color. The
cancellation is complete only when the whole optical system is
symmetrical, that is, at 1:1, however, the cancellation is usually very
good even at infinite conjugates. Correcting lateral color in
non-symmetrical lenses, like a Tessar, is not so easy, but can be done
with careful choice of glass. Kodak claimed the Ektar series of lenses had
no lateral color. They were made, at least in part, to stimulate the sales
of color films. They are excellently corrected lenses.
Kodak has a very complete filter booklet available as a PDF on their web
site. It explains how to calculate the Kelvin change for decamired
filters, among other things.
http://www.kodak.com Click on "Service and Support" and from their on
"Library". There is a ton of stuff there.
----
From Hasselblad Mailing List;
I did some portrait work with the 100 - mostly wide open at f3.5 The
results on Fuji Astia and Fuji RMS 100/1000 (rated at 200) were fantastic.
I was as please as any Leica lens I have used, plus the medium format
size. The 100 worked great for aerials at 13,000 feet and sure holds its
own at about 4 feet, too.
BTW, relating to an earlier thread, I got the 100 used at a good price
because of a nick on the rear element. I have not been able to detect any
problems, even with Cibachrome enlargements to 16x20.
Regards,
...
From Rollei Mailing List:
you wrote:
Also shine a flashlight through it and check the condition of the cement
in the cemented elements. Some lenses of this period were cemented with
synthetic cement which becomes turbid with time. That louses up contrast
and can make the lens look soft.
This is a different sort of failure from what you find with Canada
Balsam, where usualy the cement just starts to oxidize and crystalize at
the edges. The "warm" quality of some Xenons may come from cement which
has started to oxidize and discolor a little.
----
From Nikon Mailing List;
From my experience I've found more than dust in the new 80-200 AFD
lens. When I got the lens it had scratches behind the front element
meaning inside the lens. The outer surface of the front element was
fine. I'm waiting for the AFS version of the lens and hopefully it'll be
dust and scratch free.
Dave
...
From Rollei Mailing List:
It's not the glass that's affected by thermal expansion. It's the metal
barrel. That's why the problem gets worse the longer the barrel is.
Mirror lenses use a folded optical path which magnifies the effect along
with the focal length. I know no mirror lens that does not focus past the
infinity mark on the distance scale.
Depends on the element. Apparently the paint does not stick well to some
types of optical glass, so not all elements are edge-painted. I took apart
a Schneider 180mm f/2.8 not long ago and found all elements edge painted
except the second element. Schneider says it is made from ULD glass, and
they do not paint elements made from that glass.
Bob
[Ed. Note: Thanks to Kent Gittings for providing this info on macro lens
testing...]
Type of lens highly corrected for field curvature at the film plane. Field
curvature is actually the most common problem with lenses that are soft
off center. But very important for a lens used for macro work because
when the subject to front element distance becomes close to the front
element to film plane distance the light path is no longer a hypothetical
parallel set of light rays. Instead it becomes a reverse of the
concentration of the light by the optical elements. This makes the light
passing through the edge of the lens take a longer path before it gets to
the lens, leading to differences in focal point between edges light rays
and center ones. A so called flat field lens has optics that take this
into account when the lens to subject distances starts to get short.
Good test of a macro lens is to go to the close focus point and look at a
sheet of some pattern. If the focus at the center is the same (not just in
the DOF range) as the edge it can be called a flat field lens. If on the
other hand moving the focus ring gives an expanding or contracting in
focus area it is not. If not it is exhibiting field curvature.
For instance astro telescopes used for photography (sky usually) generally
have a multi optic device called a telecompressor/field flattener that
flattens the field at the film plane and act as reverse teleconverters to
speed up the shorten the focal length (F10 can go to F6.3 or even F3.3
with some).
Kent Gittings
From Rollei Mailing List:
you wrote:
A haze inside a lens can also be just stuff deposited on the inside
glass surfaces over a long period of time. This stuff comes off with any
lens cleaner. Virtually all older lenses develop it.
The effect of degenerating synthetic cement is a haziness in the cement
layer. This is often turbid. I have a couple of Kodak lenses where it has
a sort of orange peel look. Getting rid of it requires re-cementing the
lens. Canada balsam can also turn milky but its usually a vert strong
effect like Opal glass. I've seen this in very old aerial lenses which
were subjected to very low temperatures which crystalized the cement.
Haze on the interior surfaces of a lens raise havoc with the contrast of
the lens. I think many old lenses which are thought to be low contrast due
to lack of coating are actually hazy. It doesn't take much to produce the
effect. I've seen haze in lenses which were only about 20 years old.
Some lenses are easy to get apart for cleaning, some are a PITA.
Schneider lenses often have extremely small set screws which are easy to
miss.
Mostly they come apart pretty easily. A flashlight is a very useful tool
for inspecting lenses. Shine it through the lens to look for haze, bad
cement, and paint flakes, shine it across the surfaces to look for
scratches, gouges, and pitting.
----
[Ed. note: the black dust in many lenses is worn off the edges of the
elements, where it is painted to reduce flare etc...]
you wrote:
The need for edge paint depends on whether any light can strike the edge
at an angle where it will be reflected back into the lens. Thick elements
are almost always coated with an anti-reflection paint, thin elements may
not need it. For example, the postitive elements of an Apochromatic Artar
are very thin at the edge and are not painted, the negative elements are
thicker and are painted.
----
From Rollei Mailing List:
The seperation you have read about on this list is lens element
seperation, not coating seperation. Lens element seperation happens when
the glue which holds two lens elements together fails. The most likely
thing to happen to coatings is scratching due to poor cleaning methods.
Both problems can be seen by using a torch to examine the lens. Lens
seperation typically shows as "shiny" bits towards the outside of the
lens. Often there will be several "spots" in a circular pattern. More
advanced cases will show a complete ring with a smooth outside edge and a
rougher inside edge. If you ever see a lens with element seperation you
will immediately know what it is. For checking the coating shine the
light trough the lens and also across the surface (reflecting the light
from the surface of the lens). While you are doing this check for any
fogging of the lens, and also for any dirt etc. inside the lens. Don't be
too fussy.
There are reports of some of the last of the F models having HFT coating.
On most F models they will be the same as the E.
Coatings are amongst the least of your worries. More importantly look for
a nice clean camera, no dents, no signs of "rough" repairs, check the
shutter at all speeds. Check all controls operate freely and smoothly.
Find an object far away (over 1km) focus to infinity and check the
viewfinder image is sharp.
Check that the gap where the lens board overlaps the body is the same all
around. Look for dents. Check the back clamps firmly when closed.
I am also in Australia. If you need help
contact me off list and we will see what can be done.
Richard
Richard Urmonas
From Contax Mailing List:
Not necessarily, Joe. Some of the special glass types used in Canon L
lenses and top end lenses from Leica and others are more prone to bubbles
than ordinary optical glass. If they rejected every blank with a few
bubbles these lenses would cost a lot more than they already do. I've
watched LD glass made in the Lietz works in Wetzlar and it is a
surprisingly low tech operation.
I don't much care if a lens has a few bubbles in it, so long as it
performs properly.
Bob
From: dickburk@ix.netcom.com (Richard Knoppow)
Fishhead fishhead76@MailAndNews.com wrote:
The shutter is probably a Supermatic (X) shutter with strobe only
synch. If its a Flash Supermatic with a slider for M and F bulbs it
will still synch strobe, just don't cock the synchronizer. For strobe
the position of the M-F slider makes no difference.
I use mine with the Vivitar you have, it works just fine. You need an
adaptor cable to go from the bi-post connector to the PC connector on
the flash. Paramount cables makes these, not cheap but you only need
one.
The blue tint is single coating.
A few bubbles in the front element make no difference, its a result
of the very high melting temperature of the glass used.
Scratches (so called cleaning marks are scratches) can be harmful
depending on how many there are. A single scratch or a couple don't do
much damage, but if the thing looks like its been cleaned with steel
wool the result will be very low contrast due to the diffusion from
the scratching.
The design is very similar to the 127mm, f/4.7 Ektar and other Ektar
lenses in this series. They are corrected for color photography and
are extremely sharp.
Most older lenses get a coating of haze on the surfaces inside the
front cell. This haze does serious mischief to the contrast of the
lens. It can be cleaned off easily with any lens cleaner. The front
cell of the 152mm Ektar has a back cap whcih unscrews making it easy
to get to the inside and clean.
Unless it has been scratched badly enough to damage its performance
it should be a very fine lens.
---
From Rollei Mailing List;
jerryleh@pacbell.net wrote:
Yes. It has a different appearance from glass-air reflections... duller,
fainter, but it's there...
Eric Goldstein
From Rollei Mailing List:
you wrote:
Yes, the reflections are dim but visible. In a modern multi-coated lens
telling the cemented surfaces from the air surfaces may be difficult but
in single coated or uncoated lenses the air surfaces are much brighter.
This works provided the lens isn't too elaborate.
Thanks for _absolutely_ confirming that the Hassy Ektars were Heliar
types. I bet Voigtlander never built any as good as Kodak's:-)
----
From Contax Mailing List:
Austin,
Here is an interesting bookmark on this topic:
http://www.astropix.com/HTML/I_ASTROP/FOCUS/FOCUS036.HTM
The answer seems to be that there is no focus shift IF you have an
apochromatically corrected lens AND the light rays are parallel in front
of the lens. I take this to mean that you will get varying degrees of
focus shift with wider angles and non-apo lenses. A formula is provided.
Bernard
From Leica Mailing List:
Douglas Cooper at douglas@dysmedia.com wrote:
I can only give you my practical experience, which is that that web site
is largely WRONG. Cleaning marks, in the sense of a lot of filigree
scratches, completely screw up the behavior of a lens when pointed at
anything remotely resembling a bright light. In this respect they are much
worse than great big gouges in the front of the lens. You always hope
they're not going to matter but, unless they really ARE light, in my
experience they do.
If you don't habitually use your lenses wide open or shoot into the light
then you probably won't notice it as much.
- --
From Leica Mailing List;
Douglas Cooper wrote:
I hate to speak for Ken, but the above certainly does NOT reflect more
than ten years of conversations I have had with him on this topic. I
would suspect that Ken probably gave you VERY cautious advice, along the
lines of 'regrinding of a lens can change the optical performance'.
In any event, most "cleaning marks" on older Leica glass are not "cleaning
marks" at all, but artifacts of the wet coatings used by Leica until 1958;
these coatings dry out and leave identifiable marks on the lens. Having
these removed and the lens recoated will not alter the optical properties,
as no glass is removed. A true nick or ding or gouge is a different
matter: if the lens is otherwise all right, then perhaps the best thing
to do is to blacken the gouge with a magic marker of some sort to reduce
flare.
Marc
msmall@roanoke.infi.net
From Nikon Mailing List;
After many scratched lenses, I've found the best way to check for
scratches under a fluorescent lamp is to move it off to the side of the
light fixture. That way you won't be looking directly into the lens but
rather the light will be hitting off to the side. Any scratches on the
lens will show up because it'll reflect the light due to light hitting the
scratch at an angle.
mynikon@maxis.net.my wrote:
Date: Wed, 06 Jun 2001
James Meckley jmeckley@pegasus.cc.ucf.edu wrote:
Let me disagree with this. "Cleaning marks", if they are bad enough
can destroy the contrast of the lens. A couple of scratches won't
cause noticable harm, but some lenses look like they've been rubbed
down with sandpaper. You _can_ see the difference. A lens with "slight
cleaning marks" may be badly scratched, the marks being "slight" in
the eyes of the seller.
A small flashlight (UK = torch) is very helpful for inspecting lens
condition. Shine the light through the lens to look for haze,
separated elements, paint chips inside, etc. And shine it across the
surfaces to look for scratches, scuffs, gouges, etc.
---
From: slberfuchs@aol.com (Ted Harris)
It also helps to do the tests Richard suggest while examining the lens
surface with some sort of a loupe. I generally use an 8x. After doing
that I go back to a naked eye final evaluation.
Ted
Date: Thu, 07 Jun 2001
"Photographter" fuji3@kornet21.net wrote:
A "cleaning mark" is a euphemism for a scratch, usually minor, in
the lens coating and perhaps into the glass. "Cleaning marks" are of
course the plural.
One or a few minor marks will have no visible effect on lens
performance...but the operative term "minor" and "few," and the fewer
the better. A significant number of cleaning marks will reduce
contrast and increase halation.
Personally I'd accept a lens with perhaps up to two or three really
minor marks but no worse.
The reason the euphemism is used is that no one will buy a
"scratched" lens. Remember, the seller's "cleaning mark" is the
buyer's "huge gouge."
---
Newsgroups: rec.photo.equipment.medium-format
The flecks of gold are actually brass and yes the dusting may reoccur.
The brass comes from a few moving parts in the shutter that are not
properly lubricated. Havint the lenses cleaned will not solve the
problem. The hair, if thats what it is, could have entered the shutter
when the lenses were removed and is noe just showing up.
Mike
"Katherine Hester and Mark Carubia" khandmc@bellsouth.net wrote
From: dickburk@ix.netcom.com (Richard Knoppow)
andermar@teleport.com (Mark Anderson) wrote:
Try flat black paint. The scratch will scatter some light but maybe
not much. Check the image on the ground glass and inspect the lens
from the back. If there is not any visible flare from the scratch
just leave it alone. A single scratch on the front surface doesn't
cause much harm. On the rear surface it may cause more trouble because
the light there isn't collimated. You may get away without any
noticable effect, especially if the scratch isn't right in the middle.
---
Date: 25 Jul 2001
It will also depend on the location of the scratch and its depth and
width. if it is minor and out toward the edge of the lens I wouldn't
bother doing anything.
Best bet is to shoot some film and see what results you get. If you do
notice flare then filling it in can help some if it is done carefully.
Generally small scratches aren't worth bothering with although they will
greatly reduce the resale value of the lens.
Ted Harris From: Paul van Walree <odobenus@xs4all.nl> It has been a while since I announced my page on chromatic aberrations
from minolta mailing list:
Date: Thu, 21 Feb 2002
From: "Emmanuel Seynaeve" emmanuel.seynaeve@vsk.be
Subject: Re: Coating Scratches
----- Original Message -----
From: "aj_at_work2002" antony.hands@national.com.au
To: ManualMinolta@yahoogroups.com
Sent: Thursday, February 21, 2002
Subject: [MinMan] Coating Scratches
Hello,
I own an 135 f2.8 MC with cleaning marks on it. They are hard
to see looking at the front, but when looking through the lens
from the rear to a light source, I can see them clearly. When
you ask me for a number, I should say 25 to 30, varying from
a few millimeter to 1,5 centimeter.
I has no effect at all, A/B compared with my clean MD135 f3.5
Ironically, I always use my MC.
I don't know the limit for affection on the picture, but I think
it will be very high.
Emmanuel Seynaeve
> Hi all,
>
> Occasionally I see lenses for sale which I might want but that have
> many thin sratches to the coatings (not the glass itself) of the
> front element (from cleaning etc). The price is naturally right in
> these circumstances, but I have always shied away due to concern that
> these type of scratches may affect the image.
>
> Has anyone got experience in this, and will such scratches affect the
> images?
>
> Antony
Date: Sun, 03 Feb 2002
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: RE: [Rollei] OT Easy service lens (was felt and plush : a possible source)
you wrote:
>That sounds like a cool design. I wonder why the newer
>lenses aren't as easy to service as your older one? Not
>that you need to do it often, but dust and other particles
>eventually creep in between the elements eventually.
>
>> I just got a Zeca 9 x 12 camera with Unofokal lens. This lens is
>> great and
>> really easy to clean. It's possible to screw lose all lens elements and
>> clean them. No cemented lenses, never a risk for separation. :-)
The problem comes with small sealed cells. While larger lenses very often
have back caps which unscrew many smaller lenses have front retaining
rings. These unscrew too, but it may not be obvous. Many lenses have the
threads painted over so it looks like there is no way of getting them
apart. Retaining rings of this sort are removed by using a tubular friction
tool. A few have slots in them (Schneider does this) but the friction tool
is safer even when there are slots.
What I've observered is that older lenses often get hazy inside. I don't
know the source of the haze definitely but I think it may be something
evaporated from the anti-reflection paint in the cell. In any case it comes
off very easily once you can get access to the lens surface.
This haze completely destroys the contrast of the lens. I suspect many
old lenses which are thought to be low contrast due to lack of coating are
actually just dirty.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From Russian Camera Mailing List:
Date: Tue, 29 Jan 2002
From: Ron Schwarz rs@clubvb.com
Subject: Re: Fixin these is a blast!!!!
>Listed in "Files" under wanatunda and "Bikes" and "Chairs".
>Cleaned up real good, aperture ring is now "quality snug" and
>clicking instead of gliding loosely, and the coatings appear
>undamaged except for a small chip but so far not showing in the
>images.
They look good. Don't worry about the chip. I have a Nikkor 85/2.0 I bought
for $29 completely disassembled, with a chip in the front element. It does
beautiful work. Back in the olden days, no discriminating photographer worth
his salt would buy a lens that didn't have at least one bubble in the glass.
It was hard to make good optical glass back then, and bubbles were common
in the best glass. They didn't degrade the images at all, even though
they're more noticable than a small nick in a lens.
The only thing a small chip affects is the resale value. {g} (And I've never
sold a good working lens and *not* later regretted it, so my philosophy now
is to keep what I like, and not buy it with the idea of reselling it later
on.)
From: edgy01@aol.com (EDGY01)
Newsgroups: rec.photo.equipment.35mm
Date: 29 Jan 2002
Subject: Re: lens seperation??
What does lens seperation or seperation between the lens mean?. I know it
can't be good but how do you look for it. Are the signs of this obvious?.
The optics within photographic lenses are composed of elements and groups (of
elements). When two or more lenses are glued together they compose a 'group.'
The design characteristics of the lens determines whether they should be a part
of a group, or help separately in the mount as just an element. Over time, or
aided by poor manufacturing in the first place, the glue can fail and the
elements that make up a group can begin to separate. This separation changes
the entire lens internally and more importantly, optically. The signs of it
are the usual,--does deliver good pictures, fuzzy, etc., and can sometimes be
seen when looking through the lens yourself where you can see what appears to
be something other than a perfectly clear view from back to front. The signs
should be obvious. Sometimes the lens will even rattle a bit depending upon
the construct of the lens.
Unless the lens is a very special collectible lens, I would walk (or even RUN)
away from that lens. It could cost a bit to repair.
Dan Lindsay
Santa Barbara
From Rollei Mailing List:
Date: Sat, 30 Mar 2002
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Lens problems
you wrote:
>Thanks Phil......Can anyone tell me how to identify separation when looking
>at the lens?
>
Separation shows up in a couple of ways. The sort also depends on the
kind of cement used on the lens. Lenses made up until the end of WW-2 were
mostly cemented with Canada Balsam, essentially a kind of pine tree sap.
During the war synthetic cements began to be used for aerial camera lenses
because Canada Balsam does not tollerate temperature extremes and lenses
used at high altitudes are subjected to very cold temperatures. the balsam
would almost instantly crystalize and turn cloudy.
Balsam cemented lenses tend to dry and crystalize at the edges of the
lens. The balsam there also oxidizes somewhat. The usual symptom is a
yellow or brown circle around the periphery of the lens. Sometimes the
crystalization is obvious, particularly on very old lenses. Such separation
does little harm when the lenses are used stopped down.
Balsam can also separate in spots, looking like little bubbles. The
apearance is different than the bubbles sometimes found in old type high
index glass, smaller and more scattered.
Several types of synthetic cements have been used over the years. The
earliest was thermo-setting. If it was not properly cured it sometimes
separates after a time. I've seen this kind of separation in both Zeiss and
Wollensak lenses. It appears in the form of large bubbles. Balsam can
separate like this also but I've seen that only in projection lenses
subject to heat.
I don't know when Schneider started using synthetic cement but one
Rolleicord IV I had showed typical balsam discoloring at the edges of its
Xenar lens
Very old Zeiss lenses, pre-WW-2, seem to hold up better than other
brands. Perhaps Zeiss had some secret type of cement or perhaps was just
more careful about cementing.
Synthetic cement can also become turbid. I've seen this on a couple of
Kodak lenses. The cemented surface looks "dirty" when examined by
transmitted light. A magnifying glass shows the cemented interface to have
developed a sort of fin orange-peel look. This effect completely destroys
lens contrast.
Lenses can be re-cemented. Its not an inherently difficult process.
However, many lenses, such as the rear component of Tessar types, are in
spun mounts requiring machining to remove the glass and the creation of a
back cap to remount it.
Most cemented elements are located by having precision ground edges and
are centered automatically if edge clamped. Some lenses have cemented
elements of different diameters requiring a fixture of some sort to hold
them and some form of optical centering to locate them. The Schneider
Angulon is such a lens.
Separation can be seen by examining the lens with a flashlight, with both
transmitted light and by shining it across the surfaces. This will also
show up other problems such as flaking edge paint or internal
anti-reflection paint in lens cells, and scratches, scuffs, etc. Its a good
idea to take a flashlight and low power magnifier along with shopping for
used cameras or lenses.
Note that many lenses develop an internal haze with time. This usually
cleans off easily once you can get to the lens surfaces. This haze can mock
the turbidity of a layer of degraded cement so some care must be excercized
in examining lenses.
>>John Perry wrote:
>>>
>>> Are any of the Rollei taking lens more prone to separation or other
>>> problems? If so, which ones and what what models are they found on?
>>> Thanks in advance.
>>
>>>From my limited experience, the Schneider Xenotars of the early 60's are
>>more prone to separation issues. I've also seen fungus in a few 50's
>>cameras, Xenars in Rolleicords. I think a close examination (flashlight
>>shone from behind with shutter open) of any particular lens is worth a
>>lot more than generalizations about years and models.
>>Regards,
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From hasselblad mailing list:
Date: Tue, 19 Mar 2002
From: "ian.barnes" ian@ianbarnes.co.uk
To: hasselblad@kelvin.net
Subject: RE: [HUG] 50mm T* lens with heavy marks
Interesting strand.
I was given a 150 c which has been dunked and has a big ding on the front
element.(Looks like an air gun pellet has hit it)
I have had a lot of fun stripping it and reworking it but have yet to test
to see if the ding affects the image.I have been advised by Peter R to paint
the ding with black to reduce the flare.I looked into getting a new front
element and from memory Zeiss no longer do them and the price would be
uneconomic. My opticians said it would be possible but as the lens was a
'doublet' and we did not know the refrective index of the glass would not be
practicle.The cheapest conclusion is to try it and hope for the best or try
to find a right off 150 with a good front element and make one good one from
two.It may be possbile to get yours polished professionally? In my case I
know of a dealer who has a 150 with a badly dinged front casing and it would
be easy to mix and match. I know the rear element comes out as a group of
lens in a carrier.(similar to removing a spark plug but a bit more
exciting).For ease I would assume the whole lot would have to be replaced in
your case.Why not contact Peter R and the other pro repair men in the USA
and see if they have a spare back element?
How about trying to price the new / secondhand element (or polishing it),
add on a value for a cla and put this to the seller. May be offer $100.I
would have thought if it does the job at $150 that was pretty good if you
are happy to live with it.If it is black already the smoke damage would
blend in well.
IMHO these lens are worth restoring as they are bullet proof and if like me
you cannot afford a newer lens $100 - 150 sounds like a good idea.
Ian
-----Original Message-----
From: Christopher Williams [mailto:LeicaChris@worldnet.att.net]
Sent: 19 March 2002 03:41
To: hasselblad@kelvin.net
Subject: [HUG] 50mm T* lens with heavy marks
I just recently looked at a very ugly 50mm T* chrome lens.
After going through a small fire, the lens has seen better days.
The rear element has many scratches and coating marks, and a few dings. The
front element is in better condition.
I tested this lens with a roll of XP2 400 and to my surprise, the images
looked damn good! I was always told that if the rear elements have deep
marks, move on. Even at 8x8 sixe, there was no softening or glare. Images
were shot inside and outside.
Lens is going for $150. Is it possible to order new rear elements for this
lens?
Chris Williams
New Orleans
Date: Wed, 17 Apr 2002
From: "Jay Y Javier" nikitakat@edsamail.com.ph
To: russiancamera-user@beststuff.com
Subject: Re: [Russiancamera] Is there a good way to offset the yellowish tint?
Tongzhi Zhang
I too have 'huangse xiangbian' syndrome with some Jupiter 9 lenses. It
seems that the bluer they look, the yellower the pictures they make.
Other 'blue' lenses, however, don't do the same.
A 'cooling' filter (very pale blue) should be able to take care of the
excessive yellowing.
zaijian
Tongzhi gongren Jay :)
russiancamera-user@beststuff.com wrote:
>Hi comrades,
>
>The only major reason I don't use those old Russian lenses for color
>pictures or slides is the sometimes very obvious yellowish tint.I am not
>sure if this subject has been discussed before. However, It would be of help
>if some member comrades have got good ways to offset the yellowish tint.The
>rsolution and contrast of the older lenses are usually very high.
>
>Perhaps some color filters could be a remedy? I recall someone suggested
>putting the lens in a microwave oven and heat it to some hundreds of degrees
>centigrade. I don't believe it is the right way.
From hasselblad mailing list:
Date: Sun, 21 Apr 2002
From: "ian.barnes" ian@ianbarnes.co.uk
Subject: [HUG] Test results of a lens with a serious chip on the front element
Hello
For reference I have a 150c with a chip on the front element that would make
you weep. Looks like an airgun pellet have been shot at it.
After Peter Rosenthals reccomendation to 'Paint' the chip with black I
tested it with a polaroid shot.
Simply you cannot see the fault at f11. The only comment may be the picture
is a little say half a stop dark / underexposed which may be me or the
Paint??? (presumably dark on a polaroid is under exposed??)
Ian
from hasselblad mailing list:
Date: Fri, 26 Apr 2002
From: Henry Posner/B&H; Photo-Video henryp@bhphotovideo.com
Subject: [HUG] Re: Test results of a lens with a serious chip on the front element
you wrote:
>May be an apocryphal story, but does anyone else recall reading that
>Edward Weston for years used a lens that had a *cracked* front element
>and used it to make some of his most famous images?
I don't recall a Weston story, but in her autobiography Portrait of Myself,
Margaret Bourke White relates that the first camera she earned money with
was a TLR with a significant divot in the shooting lens.
--
regards,
Henry Posner
Director of Sales and Training
B&H; Photo-Video, and Pro-Audio Inc.
http://www.bhphotovideo.com
from hasselblad mailing list:
Date: Fri, 26 Apr 2002
From: george day geod@sbcglobal.net
Subject: Re: [HUG] Re: Test results of a lens with a serious chip on the front element
First image I ever published was taken with a Canon FTb-QL (loved that
camera!) and a 35/2.8 FD lens with a huge scratch on the front. Used that
lens for at least a couple of years, shot hundreds and hundreds of slides
and never noticed a problem.
...
from hasselblad mailing list:
Date: Mon, 22 Apr 2002
From: Bob Keene/Keene Vision Photography kabob3@attbi.com
Subject: [HUG] Re: Test results of a lens with a serious chip on the front element/ FS Tuesday!
Ian-
I totally AGREE with your findings! I have (as a matter of fact, am SELLING)
two lenses with nicks in the front elements!
My 150 Black C T* #5761456, has a small nick on the front element i used a
black 'Sharpie' marker to just put a black dot on the nick- you would NEVER
know from the results that there was anything less than perfect about this
lens. I've used it for four years to make and sell wonderful images. Had the
pc post upgraded to the collar socket type for more reliable sync
connection. Asking $600 plus shipping for this wonderful lens. A great price
for a great lens. Focus ring is smooth and buttery, but not loose. Will
include a Bay 50- Bay 60 Hasselblad adapter ring for $75.
My Chrome 50 C Distagon (#4167094) also suffered a small ding on the
frontelement (use your lens caps boys and girls! - happened while changing
lenses, dropped my 60 on the 50- sigh!) has a small 'ding' - BUT- for the
life of me, I cannot see any difference in images taken with this lens now
as opposed to when there was no ding! Even wide open (which is what I've
used it alot- doing wedding hall, church overall shots). Asking $500 plus
shipping. Including screw on rubber lens hood.
Personally think that front element damage is over-rated! I've used these
lenses with NO problem, even shooting into light sources.
Also selling a very worn, but clear NC-2 prism- $175 plus shipping.
I also have an 80 CF T* and a 503CX body on a popular auction site that
rhymes with "D-day" ;)
I will soon be selling some A-12 backs and an A-24 back, as well as some
other stuff.
Regards,
Bob Keene
Keene Vision Photography
"Creating Visions That Last A Lifetime"
781/449-2536
www.keenevision.com
Hasselblad at hasselblad@kelvin.net wrote:
> Date: Sun, 21 Apr 2002
> From: "ian.barnes" ian@ianbarnes.co.uk
> To: "Hasselblad@Kelvin. Net" hasselblad@kelvin.net
> Subject: Test results of a lens with a serious chip on the front element
>
> Hello
> For reference I have a 150c with a chip on the front element that would make
> you weep. Looks like an airgun pellet have been shot at it.
> After Peter Rosenthals reccomendation to 'Paint' the chip with black I
> tested it with a polaroid shot.
> Simply you cannot see the fault at f11. The only comment may be the picture
> is a little say half a stop dark / underexposed which may be me or the
> Paint??? (presumably dark on a polaroid is under exposed??)
> Ian
from hasselblad mailing list:
Date: Tue, 23 Apr 2002
From: "ian.barnes" ian@ianbarnes.co.uk
Subject: RE: [HUG] Re: Test results of a lens with a serious chip on the front element/ FS Tuesday!
Thanks for the response.Glad your lens are doing well.
I must admit I really would not know how to price this lens if i ever sold
it.Its not for sale but if anyone would like to like to say how much they
would be pay for It would be very interesting.Apart from the 'ding' it is
a really clean 150 C.that work well. Perhaps i will let a student have it
cheap someday.
With my 'ding' being so big do you think the area of black accounts for the
say .5 stop loss of exposure?(About 4mm across ) This was on 125th at f11 on
100asa Polaroid.It may just be my metering.It was a perfect sunny 'Kodak'
day.
Ian
...
From: brianc1959@aol.com (brian)
Newsgroups: rec.photo.digital,rec.photo.equipment.35mm
Subject: Correct those aberrations!
Date: 5 Apr 2002
Everyone knows that lenses perform better when you stop them down, at
least up to a point. Thats because stopping down reduces or eliminates
aberrations that degrade images. What is not so widely known is that
there are two aberrations that are completely unaffected by stopping
down: distortion and lateral chromatic aberration. Lateral chromatic
aberration, or color fringing, is normally the only aberration that
can significantly degrade image sharpness at small apertures.
Fortunately, both of these aberrations can be eliminated to a
remarkable degree using the Panorama Tools plugin for Photoshop. I
wrote a tutorial on how to figure it all out yourself for any
camera/lens combination:
http://www.caldwellphotographic.com/TutorialsDistortionAndColorFringing.html
The calibration process is somewhat involved, but I have tested and
calibrated a number of lenses myself using the Nikon D1x, and I've
just put up a large number of new pages on my website that show the
calibration coefficients along with before/after mouseover images of a
test scene: http://www.caldwellphotographic.com/ccmain.html
The lenses include wideangle, normal and telephoto primes, as well as
several zoom lenses, including the 17-35AFS, 24-85AFD, 70-180Micro,
50-135AIS and 80-400VR. All of the marked focal lengths for the zoom
lenses are shown on the test pages.
Note that these tests were done on a relatively distant target, and
the results may not be accurate for extremely close focus distances.
It turns out that the wide angle prime lenses benefit most from the
calibration process, although some of the longer lenses and certainly
some zooms benefit as well. Interestingly, of all the lenses that I
tested only one proved to have no measurable distortion or color
fringing: the 105mm f/2.8 AIS Micro-Nikkor.
The calibration coefficients that I found will be applicable to any
camera accepting Nikon lenses having a 1.5x crop factor. This includes
all of the Nikon D-series (D1, D1x, D1h, D100) and the Fuji S-series
(S1 and S2). The Kodak cameras have a 1.3x crop factor and will
require different coefficients
I would be interested in hearing positive or negative reports from
anyone trying out these coefficients with their images.
Brian
--
Brian Caldwell
http://www.caldwellphotographic.com
From camera fix mailing list:
Date: Mon, 29 Apr 2002
From: Bob Shell bob@bobshell.com
Subject: Re: Cloudy lens
Kenith Ryan at kryan@wireco.net wrote:
> There is a lens on eBay that I am thinking about bidding on. The only thing
> that is holding me back is that "some of the glass has a light cloudy look",
> accordind to the seller. I am wondering whether this cloudiness could be
> cleaned off or if it is a lost cause. Other than the cloudiness he says the
> class has no other defects.
What lens is it? Some types of optical glass, particularly some of the low
dispersion types used in modern telephotos, are subject to staining which is
almost impossible to clean away. So whether it could be cleaned would
depend on what lens it is and which elements are cloudy. This could also be
a problem with old optical cement if it is an older lens, and that's another
matter entirely.
Bob
From camera fix mailing list:
Date: Mon, 29 Apr 2002
From: Gene Poon sheehans@ap.net
Subject: Re: Cloudy lens
Kenith Ryan wrote:
There is a lens on eBay that I am thinking about bidding on. The only thing
that is holding me back is that "some of the glass has a light cloudy look",
accordind to the seller. I am wondering whether this cloudiness could be
cleaned off or if it is a lost cause. Other than the cloudiness he says the
class has no other defects.
What kind of lens?
A lot of Leitz lenses from the early M-mount era and before, do that. I have an
M-mount 135mm that I bought, thinking it was a film of evaporated oil from the
mount grease. Wrong...it won't clean up.
-GP
From rollei mailing list:
Date: Tue, 21 Nov 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] lens dust
you wrote:
>Hello all,
>
>I've been on a quest to find a cheap and useable Rollei TLR Planar/Xenotar on
>Ebay. Although a lot of stuff on E-bay is junk, I figured that something
>worthwhile must show up at some point. I've already sent back cameras twice
>due to defects. The latest I have acquired is a 3.5F type II Xenotar. It is
>in very good shape, with an excellent case and a plastic cap. The lenses are
>scratch free... but... the problem is that there is a lot of dust in the
>taking lens... throughout (not just on outer or inner surface). Also, the
>speeds are a bit off, as can be expected with these old cameras, as is the
>light meter.
>
>I have a few questions regarding this camera. 1. Will the dust in the lens
>interfere with picture quality? I've shot a test roll which looks okay,
>though there are dust specs on the negatives - would these be a result of the
>dust in the lens, or other dust in the camera, etc? Also, how difficult and
>costly is it to have the lenses cleaned out if I already plan to have a CLA
>done on the camera. Finally, regarding the light meter... is there any
way to
>repair or recaliborate it?
>
>Thanks in advance for any advice,
> David
The question about dust _inside_ a lens is: where did it come from?
This may be anti-reflection paint from the inside of the cell flaking off
or it may be some kind of fungus. You may be able to tell more by examining
the lens with a loupe and small flashlight.
Most lenses are fairly easy to open for cleaning. If the glass is OK
paint or actual dust can be blown out and the surfaces cleaned with lens
cleaner. Don't worry about centering, its done automatically by the design
of the lens mounting. The elements are sandwitched between two rings
which contact the glass only near the edges. Because the surfaces are
spherical this arrangement will automatically center the lens.
Mostly lenses have threaded retaining rings on the front. Often they do
not have slots or dots. These are removed by friction using a tube of the
right diameter with double-stick tape on the edges. Some Schneider lenses
have tiny set screws to hold the cell together. I've seen this on Rollei
finder lenses made by Schneider. It is sometimes hard to find them.
Cleaning the shutter is made more difficult because it needs to be
removed from the camera for a proper cleaning. In any case a fair amount of
disassembly is needed simply to get to it. Its better to send the thing to
H.Fleenor and get it overhauled. This is something that needs to be done
once in twenty years so its really not expensive. Harry can clean the lens
as well as tune up the camera. Good non-out-gassing flat paint doesn't seem
to be available anymore. The best I've found is Krylon Ultra-Flat Black
paint. It comes in spray cans but you can spray some into a bottle and
brush it on. It also works on element edges. Because it outgasses it needs
to be thoroughly dried (preferably baked at 150F) before assembling into
sealed areas. This is, BTW, a good anti-reflection paint for touching up
camera interiors.
The Rollei light meter uses a Selenium cell. They tend to loose
sensitivity in a non-linear fashion when they get old. Some cells last
seemingly forever, others seem to go quickly. Heat and moisture are the
enemies. The cells are supposed to be sealed to prevent moisture from
entering but the seals don't last forever. Because the fall-off is
non-linear the meter may seem to read right for low light levels and be one
or more stops low at high levels. The only fix is ot replace the cell. The
non-linear characteristic prevents simply adjusting the film speed ot
compensate.
My impression from this list is that the cells used in Rollei cameras
were made by Gossen and are no longer available.
If the meter doesn't work at all it may actually be fixable. That might
be an oxidized solder joint or contact somewhere, or a stuck meter due to
dirt in the bearings. Usually, when the cell goes bad it doesn't die, it
just gets inaccurate.
I don't know exactly what goes into making a Selenium cell. They were the
standard cell for lightmeters until transistor amplifiers became available
allowing the use of Cadmium disulfide and other variable resistance cells.
My point is that I wonder if there is anyone who could make cells for
Rolleis at a reasonable price. I am sure such information would be welcome
here.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From hasselblad mailing list:
Date: Mon, 18 Mar 2002
From: Christopher Williams LeicaChris@worldnet.att.net
Subject: [HUG] 50mm T* lens with heavy marks
I just recently looked at a very ugly 50mm T* chrome lens.
After going through a small fire, the lens has seen better days.
The rear element has many scratches and coating marks, and a few dings. The
front element is in better condition.
I tested this lens with a roll of XP2 400 and to my surprise, the images
looked damn good! I was always told that if the rear elements have deep
marks, move on. Even at 8x8 sixe, there was no softening or glare. Images
were shot inside and outside.
Lens is going for $150. Is it possible to order new rear elements for this
lens?
Chris Williams
New Orleans
From camera fix mailing list:
Date: Thu, 02 May 2002
From: "abdon_241302" abdon@sillypages.com
Subject: Re: Cloudy lens
Chances are it can be cleaned....
More often than not "cloudiness" happens on older fixed focus lenses.
The chemicals used in the construction of the lens may begin to
evaporate over time. On virtually hermetically sealed fixed focus
lenses those gases have no place to escape and form the observable
cloudiness. While zooms do not tend to suffer from such problem, they
instead suffer from dust particles, as the zooming in and out brings
outside air into the chamber.
Is the lens coated? is it coated on all lens-to-air surfaces? I think
I recall reading about a coating-friendly solvent, but can't remember
the details...
From rollei mailing list:
Date: Mon, 6 May 2002
From: Jim Noel jimsphoto@cox.net
Subject: Re: [Rollei] Cleaning fog from Xenar
You need one drop of "Drop'l Do It".
That is the lube recommended by the Leica Users Group,and it works marvels.
Sorry, but although I have some, I don't remember the name of the
manufacturer. Perhaps the Leica people can help you.
----- Original Message -----
From: "Douglas Cooper" douglas@dysmedia.com
Sent: Sunday, May 05, 2002
Subject: [Rollei] Cleaning fog from Xenar
> I'm wondering if anyone here has opened a Xenar to clean light fog off the
> inside surfaces. Is it easy? Better left up to a pro? And what kind of
> tools would I need to get it unscrewed?
>
> Also, off-topic [Leica]: I'm trying to relubricate the focusing helicoid
on
> an old 50/3.5 screw mount Elmar. Lighter fluid freed it up a lot, but I'm
> wondering what I can put on there that will truly lubricate.
>
>
> Douglas Cooper
> http://www.dysmedia.com
From: edgy01@aol.com (EDGY01)
Newsgroups: rec.photo.equipment.medium-format
Date: 12 May 2002
Subject: Re: Particals in lens?
I purchased a hasselblad lens used. A 110mm FE, its about 5 years old and
I've had it for a week. While changing an extension ring, I noticed some
tiny black speaks inside the lens
The next time you have the lens in for service, simply have them catch the
particles and remove them. This is a good cross-check to ensure that your
repair guys are doing a good job.
More people are paranoid about a bit of dust in lenses. it's really no big
deal! i have a single fiber in the lens of my Super Wide 903SWC,--just behind
the front element. Drove me crazy for a little bit until I realized that it
just didn't matter.
Dan Lindsay
santa barbara
[Ed. note: long sold, but posted here to reassure even Hassy users about scratches ;-)]
From hasselblad mailing list:
Date: Fri, 24 May 2002
From: Bob Keene/Karen Shehade kabob3@attbi.com
Subject: [HUG] Friday? f/s
My ISP is down- this email will send whenever it goes back up- but I *AM*
writing this on Friday!
My 150 Black C T* #5761456, has a small nick on the front element I used a
black 'Sharpie' marker to just put a black dot on the nick- you would NEVER
know from the results that there was anything less than perfect about this
lens. I've used it for four years to make and sell wonderful images. Had the
sync post upgraded to the collar socket type for more reliable sync
connection. Asking $600 shipped (in US) for this wonderful lens. A great
price for a great lens. Will include a Bay 50- Bay 60 Hasselblad adapter
ring for $75.
My Chrome 50 C Distagon (#4167094) also suffered a small ding on the front
element (use your lens caps boys and girls! - happened while changing
lenses, dropped my 60 on the 50- sigh!) has a small 'ding' - BUT- for the
life of me, I cannot see any difference in images taken with this lens now
as opposed to when there was no ding! Even wide open (which is what I've
used it alot- doing wedding hall, church overall shots). Asking $525
shipped (in US). Including screw on rubber lens hood.
Bob Keene
Date: Wed, 19 Jun 2002
From: Craig Roberts crgrbrts@netzero.net
To: rollei@mejac.palo-alto.ca.us
Subject: [Rollei] THE FINAL WORD on Coating Flaws?
As I noted some days ago, I sent my 2.8E Xenotar off to John Van Stelten for
recoating after noticing front element damage. As we soon learned, I was
not alone in my observation. In fact, Douglas Cooper started the discussion
with the story of HIS 2.8E Xenotar coating flaw.
Well, I heard from John today. The good news is that my lens will "clean up
fine". Considering that the damage looked pretty substantial to me, this
should be encouraging to others concerned that the flaws were more than
"skin deep".
I asked John if he received many mid-1950's Xenotars with similar problems.
"Yes," he said, "BUT, no more than other German lenses -- Zeiss and Leitz --
of the same era." In fact, John surmised that he recoats more Leitz 50mm
Summicrons than ANY other lens...including our precious Xenotars and
Planars!!
How 'bout that?
Craig
Washington, DC
Date: Sun, 16 Jun 2002
From: Douglas Anthony Cooper douglas@dysmedia.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Coating Flaws in E Series
I bought a near mint 2.8E a while back which had only one flaw: the Xenotar
had spots -- almost flakes -- in the coating. I now find that my 3.5E2 has
a similar problem, to a much lesser degree: pin-prick spots in the coating.
At first I thought it might be fungus -- the dots cluster in a vaguely
biomorphic fashion -- but they are on the surface of the lens, which is
perfectly clear inside. Not your ordinary fungal behavior.
Also, I note that Pacific Rim has a 3.5E2 Xenotar with the same problem! I
haven't seen this affect image quality much, if at all, but it suggests that
this run of Schneider lenses might have had coating difficulties. Anyone
else noticed this, or have historical information? (I had the 2.8E recoated
by Focal Point, and it was stunning.)
Douglas Cooper
http://www.dysmedia.com
From: "Alan Chan" wlachan@telus.net
Newsgroups: rec.photo.equipment.35mm
Subject: Re: repairing scratch on inside of 100-400 lens
Date: Thu, 01 Aug 2002
True, better to rotate the lens while looking through it. If the "scratch"
moves, it's reflecion.
"Art Begun" beguna@mindspring.com wrote
> It might not be a scratch... could be an internal reflection of a
> curvature or ring fastener.
From hasselblad mailing list:
Date: Fri, 19 Jul 2002
From: Jim Brick jbrick@elesys.net
Subject: Re: [HUG] FS Friday = good deals! 503CXi-80-50-180 and more!
brad vance wrote:
>However, it has a few (4-5?) miniscule pecks towards the edge of the front
>element. The truth is you have to turn the lens to the light to see
>them. They are a fraction of a mm in size and have absolutely no effect
>on the quality of the image. I will send a scan of the front if you wish.
>and a scan of some chromes shot with it. It was shipped with a filter
>attached and the filter got broken in shipping.
Ah yes. Another testimonial of how a filter saved a lens!
Jim
From: artkramr@aol.com (ArtKramr)
Newsgroups: rec.photo.equipment.medium-format
Date: 02 Aug 2002
Subject: Re: Can't remove fingerprint from Tessar
>Subject: Re: Can't remove fingerprint from Tessar
>From: melek@fptoday.com (Mike)
>Date: 8/2/02
>steven.sawyer@banet.net wrote
>> I just bought a beautiful antique folding camera with a Zeiss Tessar
>> lens. Everything looks great but there's a big fat (and I mean fat)
>> fingerprint on the lens. I've used lens cleaner and scrubbed it the
>> best way I know how but I can't get it off. Now when I look at the lens
>> - it appears that the fingerprint is on the inside of the lens, although
>> this could be an optical illusion. The shutter (Compur) is between the
>> lenses. Is it possible that someone was repairing the shutter and left
>> the fingerprint?
>
>Not only possible but very likely.
>
>> Also, and I'm dreading this, I've heard that sometimes
>> fungus takes on a fingerprint shape, building it's empire on an ancient
>> fingerprint that was wiped off years ago. Any ideas? Thanks
>
>Not sure about this. Fungus can show up as a white spore with
>webs/fingers/branches coming from the center.
>
>These lens/shutter assemblies are fairly simple to disassemble. There
>usually is an outer retaining ring held by three very tiny screw
>plugs. Remove these, then remove the ring. Now unscrew the lens but
>make note of where the lens comes off in relation to the body. There
>sometimes is a small mark so that when screwed back on, it points to
>the infinity setting.
>
>You can check infinity by setting the shutter to "B" or "T" and
>checking the focus on a distant object with ground glass and a loupe.
>Open the lens to its widest setting.
>
>
>Don't scrub the lens too hard. Generally, some lens cleaner and a lot
>of cotton balls will do the trick.
>
>-Mike
There is acid in fingerprints that eat into the glass and cannot be removed if
the fingerprint is there long enough. Hope for the best. Be prepared for the
worst.
Arthur Kramer
Visit my WW II B-26 website at:
http://www.coastcomp.com/artkramer
From rollei mailing list:
Date: Sun, 16 Jun 2002
From: Paul Kollas pkkollas@gorge.net
Subject: Re: [Rollei] Coating Flaws in E Series
You wrote:
> I bought a near mint 2.8E a while back which had only one flaw: the Xenotar
> had spots -- almost flakes -- in the coating. (snip) I
> haven't seen this affect image quality much, if at all, but it suggests that
> this run of Schneider lenses might have had coating difficulties. Anyone
> else noticed this, or have historical information? (I had the 2.8E recoated
> by Focal Point, and it was stunning.)
My 2.8E Schneider has 4 of the spots, more or less in the center of the
lens. They are apparently on the surfaces which are cemented together. How
long did recoating take, and how much was it?
pk
From rollei mailing list:
Date: Sun, 16 Jun 2002
From: Jerry Waid jwaid@stny.rr.com
Subject: Re: [Rollei] Coating Flaws in E Series
If you do not see any adverse results from lens coating "problems" one might
ask themselves - Is it worth spending any money to get it "fixed".
jerry
...
From rollei mailing list:
Date: Sun, 16 Jun 2002
From: Craig Roberts crgrbrts@netzero.net
Subject: Re: [Rollei] Coating Flaws in E Series
Douglas Cooper said:
"...the Xenotar had spots -- almost flakes -- in the coating...I had (it)
recoated by Focal Point, and it was stunning."
Good morning,
When I acquired my 2.8E Xenotar recently I noticed what looked like a slight
haze on the front element. However, when I examined the lens from the rear
with a strong light shining through it, I was shocked to see the same
"pin-prick field" coating damage you mentioned, Douglas. I suspected
mechanical damage (abrasive dirt blown onto it or something similar), but
the viewing lens was unmarred. Hmmmm.
Well, even though the image quality produced by this Schneider lens was
outstanding and, as you say, seemingly unaffected, I sent it off to John Van
Stelten for recoating. He has it in his kind custody as we speak.
In other words, you are not alone. Perhaps we should ask John if he sees a
disproportionate number of Xenotars exhibiting this coating anomaly. By the
way, have you noticed any improvement - especially in flare resistance -
since John performed his procedure?
Craig Rioberts
Washington, DC
From rollei mailing list:
Date: Mon, 17 Jun 2002
From: Gene Johnson genej2@cox.net
Subject: Re: [Rollei] Coating Flaws in E Series
Richard,
I kind of guessed it might be something like that, and even more now, since
it has happened to others. Optical glass can be funny stuff can't it?
Aren't there any number of interesting things mixed in to achieve desired
refraction indexes and whatnot? My recollection is that these coatings are
something like microns deep. I'm pretty sure I can't see microns, even with
my Olympus 15x loupe. So these pits must go something on the order of .0001
or so into the glass for me to be able to see them. Has to be some
corrosive process, whether from some organic byproduct, or pollutants in the
air, or salts, or who knows. Darn shame though. I'm going to have to
either have this lens worked on or maybe replace it with a Tessar/Xenar,
since those will screw right in on the 3.5E, as pointed out to me by Jerry
L. By the way, anyone ever heard of Ultraflat? They're an outfit in
Hollywood who supposedly rework lenses for the movie industry.
Gene
From rollei mailing list:
Date: Tue, 18 Jun 2002
From: Jerry Lehrer jerryleh@postoffice.pacbell.net
Subject: Re: [Rollei] Coating Flaws in E Series
Peter
I've been told that alkaline cleaners may be injurious to coatings.
I tested the highly regarded lens cleaner ROR, and found it to be
alkaline, using pH test strips. I have never had a problem with
ROR though. It works.
For other than camera lenses, I use a 40% solution of ethyl alcohol
with a few drops of Kodak Photo-Flo. (Trader Joe's Vodka works
perfectly, and it's a hell of a lot cheaper than the proprietary cat-piss
that dealers charge for lens cleaner solutions).
Jerry Lehrer
From: "Pho-Ku" remove@spam.com
Newsgroups: rec.photo.equipment.medium-format
Subject: chip on front element of lens?
Date: Tue, 13 Aug 2002
I'm one of those people that aren't really overly obsessed with camera gear
and "my X lens is better than your Y"... I try my best to keep focus on the
"taking picture" side and not the camera side of photography... Hence i find
it absolutely no problem with owning a slightly chipped lens if it will not
deteriorate the quality of the photo or when its very cheap...however this
is a rather biased view....
I know that there are heaps of people here who care about their gear as much
as they care about the craft, so basically id like to know if those people
canprovide me with their extreme view (so balances out my naivety) by giving
me valid reasons... FYI: the lens is a wide angle lens with a chip thats
about 0.19% of total area of front element roughly and its about 2/3 of the
radius out from the center - so quite peripheral ... Ive learnt from other
posts that apart from reduced resale value and flare (which can be reduced
by painting the chip black with ink) the lens should function normally when
the chip is in front element
From: beasleyglb@mindspring.com (Gary Beasley)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: chip on front element of lens?
Date: Fri, 23 Aug 2002
"H. David Huffman"
From camera fix mailing list:
Date: Wed, 18 Sep 2002
From: "Mark Stuart" madfamily@bigpond.com
Subject: Yellowed Takumar 50mm f1.4 cure
Hi guys,
I've just visited our local old camera guru repairer who is also a
Pentax buff (has SP through to MZ-S) and was discussing the 50mm
yellow curse. He said with some authority that the problem is not the
element itself that yellows, but the Canada balsam in between element
1 and 2 (I think) from the mount end. The radioactivity causes the
problem via its proximity to the balsam, but it's not the glass that
yellows.
He has actually fixed this on a couple of lenses, but unfortunately
it's well outside of economic reality (AU$140). He admitted this, and
said that the owners of the two he's done insisted. Colour rendition
etc. was as per new.
Can any of you pros confirm this? How hard is this to do yourself?
Thanks
Mark
From camera fix mailing list:
Date: Wed, 18 Sep 2002
From: John Barlow BARLOWJG@CHHA.CO.UK
Subject: RE: Yellowed Takumar 50mm f1.4 cure
The best info I have found on replacing the balsam cement in lenses is on
the S K Grimes site @ www.skgrimes.com
The description is for large format lenses but I expect it is ok for all
formats.
John
From camera fix mailing list:
Date: Wed, 18 Sep 2002
From: Gene Poon sheehans@ap.net
Subject: Re: Yellowed Takumar 50mm f1.4 cure
Mark Stuart wrote:
> Hi guys,
>
> I've just visited our local old camera guru repairer who is also a
> Pentax buff (has SP through to MZ-S) and was discussing the 50mm
> yellow curse. He said with some authority that the problem is not the
> element itself that yellows, but the Canada balsam in between element
> 1 and 2 (I think) from the mount end. The radioactivity causes the
> problem via its proximity to the balsam, but it's not the glass that
> yellows.
>
> He has actually fixed this on a couple of lenses, but unfortunately
> it's well outside of economic reality (AU$140). He admitted this, and
> said that the owners of the two he's done insisted. Colour rendition
> etc. was as per new.
>
> Can any of you pros confirm this? How hard is this to do yourself?
I have never done it.
Chad, the old-time camera technician at the shop near me, says he
has decemented Canada balsam-cemented lens elements by baking them
in an oven, then cleaned off the old cement, and recemented them
with one of the UV-curing lens cements. Centering of the elements
is critical, get it wrong and you won't be able to reinstall the
cemented lens group. He suggested putting the lens elements into
their mount, then cementing and placing the assembly, in its mount,
into the UV light (or under the bright sun) for curing. This was
mostly done with Carl Zeiss lenses (Planars and Tessars in
Hasselblads and Rolleiflexes) which were so notorious for lens
separations. I will ask him what he did, next time I see him in the
shop (he is semi-retired now).
-Gene Poon
From camera fix mailing list:
Date: Wed, 18 Sep 2002
From: "Vincent" jonyquik@hotmail.com
Subject: Re: Yellowed Takumar 50mm f1.4 cure
I have repaired this kind of seperation on these very lenses in the
past by simply carefully cooking them in their holder on an electric
hot plate. The idea is to simply get the Canadian Balsam cement to
remelt and flow again, and it will clear. Once this is accomplished,
remove it from the hot plate and allow to naturally cool. If you
leave it on too long, it will cook the balsam making it brownish. If
that fails, you can clean the cement off with alcohol or acetone, and
recement them with new cement. I am not too sure about UV cement for
this purpose, but Canadian Balsam can be found to do this work
properly. Good Luck!!!
From: haijack_remove_@onr.com (RD)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: hazy lenses.. Re: An ebay Saint
Date: Fri, 20 Sep 2002
rmonagha@smu.edu (Robert Monaghan) wrote:
>A lot of
>older lenses are downrated simply because they aren't really clean.
Some time ago, I decided I wanted a fixed FL portrait lens for my AF
Nikon. I was looking for something cheap, mostly for use around the
house. What I bought was a fine old Japanese Prinz 135mm f/2.8 manual
focus, new in the box, made for non-AI Nikons.
When the lens arrived, I removed the mount and manually filed down 360
degrees of the rear shoulder, to allow mounting on my AF body. I also
removed the aperture auto lever so I could use the lens in preset mode
(the aperture closes and the viewfinder image darkens when the
aperture ring is turned). Without changing this, the body would have
no way to judge the aperture setting. I also figured most of my home
portrait shots would be taken full open, but even at f/4 or f/5.6, the
image is bright enough to focus easily. I will never use it stopped
down further than that.
Anyway, once I finished all this, I mounted the lens on the camera and
had a quick look around. I was dismayed to discover that there was a
tremendous reduction in contrast and color intensity. And this was the
viewfinder image, which often doesn't show minor defects. Actually, I
could hardly believe how bad it was. The glass looked fine from both
ends of the lens, and I even wondered at one point if Prinz had
intentionally softened the optics.
I eventually got the courage up to disassemble the front element. The
haze on the lens wasn't immediately apparent, but when I began
cleaning, a brown reside came off onto the cleaning tissue. While I
was inside, I also touched up a few areas where the grey/black coating
had flaked off the edge of the glass (the element was about 3/8-1/2"
thick, undoubtedly a sandwich)..
After reassembly, all signs of poor contrast and softness
disappeared. I have since shot a number of frames, and under the
conditions for which it was intended, the lens performs almost exactly
as I had hoped. Better color than my zoom, but perhaps not quite as
sharp as my 50mm. The sharpness issue isn't all the easy to
differentiate though, and I'm sure the lens is performing like new.
This taught me a lesson about lenses in general. I believe every lens
more than seven or eight years old should be disassembled for
cleaning, and many probably need it sooner. I just wish someone
besides me had seen the remarkable difference after putting this one
back together. Incidentally, I used Windex for the initial cleaning,
followed by a "standard" lens solution. Although I hadn't used Windex
for this previously, the rear surface did not appear to be coated, so
I wasn't overly concerned about damage.
Total cost for this brand new lens (not counting cleaning materials)
was $12, including shipping from the eBay seller. :)
JL
From camera fix mailing list:
Date: Wed, 25 Sep 2002
From: Stephen Castello scastello@cfl.rr.com
Subject: Re: what is lens "haze"
Eric Maquiling emaquili@ductape.net wrote:
>What is lens "haze" and can it be fixed? Is that a real term? Haze?
>Or it is something that could also mean "scratched". Is it different
>from fungus?
>
>TIA!
It can be a coating of dirt, oil, smoke, or the lens cement going bad. It can
be cleaned, if it's on the surface. It's usually uniform in coverage and on
the inside surfaces. It's like looking through a fog, or the lens looks like
it's been dipped in milk. Be careful, the lens coating on the inside surfaces
may be soft and easily damaged by cleaning.
Scratches and fungus are not the same as haze.
Stephen
From camera fix mailing list:
Date: Thu, 26 Sep 2002
From: "Jay Y Javier" nikitakat@edsamail.com.ph
Subject: Re: what is lens "haze"
Eric
Haze describes the cloudy appearance a lens has- it can be seen when a strong
light source is shone through it. It could be from fine cleaning marks, or
fine dirt, or condensation of vapourised lubrication on lens surfaces.
Commonly, with older glass, its the discoloured, ageing cement used to hold
some of the elements which gives the murky effect.
Discoloured cement - old Canada balsam in the case of the older lenses- is
sometimes possible to remove and replaced. Lube which condensed on the glass
may or may not be removeable.
Jay
From camera fix mailing list:
Date: Fri, 27 Sep 2002
From: "pentax_user" pentax_user@yahoo.com.au
Subject: Re: what is lens "haze"
Hi Eric,
As someone else pointed out, lens haze may be due to recondensed
lubricant on the . If haze is due to this, it is quite fixable, the
lens needs to be disassembled and the surfaces optically cleaned. The
cost will depend on how complex the lens is (ie how many elements,
zoom etc). It may be more cost effective searching for a replacement
if it is a fairly common lens (like a standard 50). If it is a rare
lens (eg macro or micro) then internal cleaning would be worthwhile).
Fungus/mould growth inside a lens appears quite different to the
above, some say it manifests as a spidery growth with a dull, low
contrast patch in the centre of the growth. If detected early enough
it can be removed fairly easily by a skilled techician (at a cost!).
Hope this in part answers your question.
Andrew B
--- In camera-fix@y..., Eric Maquiling emaquili@d... wrote:
> What is lens "haze" and can it be fixed? Is that a real term? Haze?
> Or it is something that could also mean "scratched". Is it different
> from fungus?
>
> TIA!
> --
> Eric
From: Marc James Small
Date: Tue, 17 Feb 1998
From: Richard Knoppow dickburk@ix.netcom.com
Reply to: rollei@mejac.palo-alto.ca.us
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 18 Feb 1998
From: Richard Knoppow dickburk@ix.netcom.com
Reply to: rollei@mejac.palo-alto.ca.us
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: dannyg1 dannyg1@idt.net
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Mamiya 6
Date: Sat, 07 Feb 1998
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Bronica lenses
Date: 14 Feb 1998
From: unnarsson hagu0009@mailer.student.gu.se
To: hasselblad@kelvin.net
Subject: God bless the plastic hoods!
Gvteborg, Sweden
From: Mr500CM Mr500CM@pipeline.com
Reply to: hasselblad@kelvin.net
Subject: Re: Fake T* lenses
Date: Thu, 26 Feb 1998
From: Joe McCary mccary@erols.com
To: hasselblad@kelvin.net
Subject: Re: Re: Fake T* lenses
not everyone can tell the difference between T* and nonT*, IMHO.
pat
Photo Response
http://www.erols.com/mccary
From: Fred Whitlock afc@cl-sys.com
[1] Re: Hasselblad Heresy!
Date: Thu Feb 19 1998
--
Fred
Maplewood Photography
http://www.maplewoodphoto.com
From: user@msn.com
[1] Re: Cross format lens quality?
Date: 27 February 1998
--There is no shadow without light
rmonagha@post.cis.smu.edu (Robert Monaghan) wrote:
From: Djuna Ivereigh djuna@tpp.org
Subject: Re: Fungus Amongus
From: Paul Silver psilver@silver-light.com
Subject: Re:Fungus on lenses
Paul Silver
Stock photography, photojournalism, fine art.
PORTFOLIO: http://www.silver-light.com/portfolio/
http://www.silver-light.com
Subject: Re: Fungus on a lens
From: xxx xxx@pacbell.net
Subject: Re: fungus on a lens
From: Dave Read read@physics.utexas.edu
Subject: Re:Fungus on lenses
Dave
Dave Read, Ph.D.
http://www.ph.utexas.edu/~read/
From: Chris Bitmead
Chris Bitmead
http://www.thepla.net/~chrisb
From: Robert Hudyma rhudyma@netcom.ca
Subject: Re: Dust in internal element/s
Markham Ontario, Canada L3R 5V7. Fax: (905) 475-3652
Email: rhudyma@netcom.ca
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Resolution and f stops
Date: 27 Feb 1998
Newsgroups: rec.photo.equipment.medium-format
Subject: Cross format lens quality?
Date: Tue, 24 Feb 1998
Danny Gonzalez
Subject: Response to Affordable Wide-Angle
Date: 1998-03-01
From: Peter Klosky PKlosky@bdm.com
To: hasselblad@kelvin.net
Subject: Scratches
From: Bob Keene/Karen Shehade kabob@tiac.net
To: hasselblad@kelvin.net
Subject: Re: Scratches
Date: Tue, 7 Apr 1998
From: bizarreone@pacific.net.sg
Subject: Lens Coating & dots
Singapore
Newsgroups: rec.photo.equipment.misc
Subject: Re Hot lenses
Date: 6 Apr 98
ECN - Energy Research Foundation
Department: ECN - Nucleair Research
From: Simon Stevens simon@mail.wizard.net
To: hasselblad@kelvin.net
Subject: Re: hasselblad CB lens quality
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Used Lenses/Cleaning Marks
Date: Fri, 10 Apr 1998
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Used Lenses/Cleaning Marks
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Used Lenses/Cleaning Marks
Date: Sat, 11 Apr 1998
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Used Lenses/Cleaning Marks
Date: Fri, 10 Apr 1998
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Used Lenses/Cleaning Marks
Date: Sun, 12 Apr 1998
http://www.mindspring.com/~skoontz
skoontz@mindspring.com
From: "William B. Boyle" boyle@carry.neonet.lv
Subject: Bad Bokeh
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Used Lenses/Cleaning Marks
Date: Sun, 12 Apr 1998
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: dickburk@ix.netcom.com (Richard Knoppow)
[1] Re: Coated vs non-coated
Date: Fri Apr 24 1998
steven T koontz skoontz@mindspring.com wrote:
>Well I've heard several peoples opinions on this and though I'd pass
>this story along.
>
>I just bought two old 6X9 folders with (what I thought was) the same
>lens, a schneider radionar 105 4.5 that were both in almost "like new"
>condition. Now admittedly this isn't the best lens schneider ever made
>but is is OK for casual shooting.. Well after cleaning and lubing both
>shutters, cleaning up the glass (which looked great on both cameras),
>checking focus scale and infinity focus (with ground glass on the film
>plane), and checking for pin holes ect, I loaded them up with T-max
>400 and went out testing.. I shot with both cameras on a tripod at the
>same locations using the same coated B&W yellow filter for each shot,
>with the sun to my back for each frame (no sunlight hitting lens)...
>Well when I got home, I developed the film (3 rolls in each camera)
>and was disappointed that one was noticeably contrastier and appeared
>"sharper/snapier" than the other. When printing, it was obvious which
>camera was better. Also I had hoped that the "bad" one would be the
>better of the two as it had a smoother shutter release mechanism but
>it wasn't even close.. Well a couple of days later I was looking at
>them outside on the porch trying to figure this out and noticed (by
>the purple sunlight reflection on the lens) that one was coated and
>one wasn't. Then I saw one had a red triangle (the coated one) and the
>other a white triangle so I now knew they were different.. You can
>guess which one was the bad one (obviously the uncoated one).
>
> My point of this story is: I had just tested coated vs non coated
>lenes of the same kind without knowing it (as I thought these were
>identical lenses) and found it obviously inferior to use an uncoated
>lens even with no light striking the front element.. contrast was
>noticeably lower and neg apparent sharpness was less. While they were
>equally "sharp in focus" the uncoated one appeared less so due to
>lower contrast. I had also had problems with the one other uncoated
>lens but people had told me "It doesn't make that much difference on
>simple lenses like those camera's have". Some of these people were
>folks whose opinions I value so I thought "Maybe it's something else."
>I now beg to differ.. Twice I have had this same low contrast problem
>and both times they were uncoated lenses. Maybe these people don't
>have problems with them but I will never fool with another uncoated
>lens.. Too much quality lost for me.
>--
>
>
>steve's photography & Z car stuff @ http://www.mindspring.com/~skoontz
>skoontz@mindspring.com
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Date: Sat Apr 25 1998
From: wcmarti@ibm.net
[1] Re: Coated vs non coated
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Rollei E TLR 2.8 Planar
>>recently noticed that the taking lens when held at the right angle looks
>>like some of the coating may be wearing off. You need to be in just the
>>right light to notice this (indirect daylight). If you hold the camera
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Sat, 25 Apr 1998
From: ScottG JanTamrac@worldnet.att.net
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Rollei E TLR 2.8 Planar
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Rollei E TLR 2.8 Planar
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: Peter.Kotsinadelis@exchange.Octel.com
Reply to: rollei@mejac.palo-alto.ca.us
Subject: RE: [Rollei] Rollei E TLR 2.8 Planar
From: Todd Belcher toddmb@intergate.bc.ca
To: rollei@mejac.palo-alto.ca.us
Subject: [Rollei] Rollei 2.8 Planar
todd
From: brownt@ase.com
[1] Re: Coated vs non coated
Date: Mon Apr 27 1998
Newsgroups: rec.photo.equipment.medium-format
Subject: Coated vs non coated
Date: Thu, 23 Apr 1998
steve's photography & Z car stuff @ http://www.mindspring.com/~skoontz
skoontz@mindspring.com
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Coating ID Help
>Hello fellow Rolleinuts,
>
>I am wondering if there is any way you an tell single and multicoating
>apart by the color of the reflections.
>I have for example two projection lenses for P11 and one of them has a
>bluish tint and has a smaller SN and the other on has an amber tint and
>has higher SN.
>I thought the blue color designates the single and everything is pretty
>much multicoating.
>I would appreciate any help on this issue.
>Thanks,
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: Tom Resident aquatom@pacbell.net
Subject: Re: 20/2.8 fungus
Subject: Response to Help evaluating Zeiss 6x9 folder
Date: 1998-05-01
From: "skgrimes" skgrimes@ma.ultranet.com
[1] Re: Yellowed Lens: Xenotar 150mm 2.8
Date: Tue May 05 1998
From: Shannon Young youngs@kodak.com
[2] Re: Glass Vs. Plastic
Date: Wed May 13 1998
Organization: Eastman Kodak Company
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: FUNGUS AMOUNGUS
Date: Sat, 16 May 1998 02:36:05 GMT
Newsgroups: rec.photo.marketplace
Subject: Nikon MF Lenses
Date: 20 May 1998
From: Mark Walberg Walberg@simmons.swmed.edu
Subject: Re:distortion of lenses vs distortion of viefinders
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Old lenses,Coating and Color Film
From: Todd Belcher toddmb@intergate.bc.ca
Subject: Re: [Rollei] Old lenses,Coating and Color Film
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Old lenses,Coating and Color Film
From: Dan Post dwpost@email.msn.com
Subject: Re: [Rollei] Assessing Rolleiflex condition
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Element Separation in Rodenstock Lenses?
Date: Thu, 28 May 1998
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Element Separation in Lenses
Date: Thu, 28 May 1998
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Element Separation in Lenses
Date: Thu, 28 May 1998
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://home.att.net/~k.thalmann/
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Element Separation in Lenses
Date: Thu, 28 May 1998
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: Rob lilindn@prodigy.net
Newsgroups: rec.photo.film+labs
Subject: Re: No more 126 film after 2000
Date: Thu, 21 May 1998
From: David Foy david.foy@shaw.wave.ca
Subject: Re: [Rollei] Rollei lenses
From: "Ferdinand W. Stutterheim" stutterh@noord.bart.nl
Subject: Re: [Rollei] Rollei lenses
Ferdi.
mail to:stutterh@noord.bart.nl
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Rollei lenses
>Others have commented on the predictable characteristics of German and
>Japanese lenses when compared to each other. SLR users mention it.
>
>I know exactly what you're talking about. I wouldn't have used the
>"temperature" metaphor, but now that I think of it, it's quite good.
>
>Does it come from different aesthetic expectations of lens designers? Or is
>it an artifact of different glass manufacturing variables? In other words,
>would a German-designed lens manufactured in Japan look German or Japanese?
>
>_____________________________
>David Foy
From: David Foy david.foy@shaw.wave.ca
Subject: Re: [Rollei] Rollei lenses
David Foy
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Rollei lenses
From: Eric Goldstein egoldste@bu.edu
Subject: Re: 3 classes of subtle lenses differences Re: [Rollei] Rollei
lenses
> Actually, I have seen at least 3 classes of subtle differences for lenses:
>
> a) color differences
>
> b) Bokeh
>
> c) some lenses are formulated for a particular optimum set of tradeoffs,
> which can differ between brands and designers - such as the Hassy 80mm
> having a "warmer" greater contrasty effect than similar med fmt lenses.
> Other lenses are almost too sharp for most of us (hence, softars ;-)
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Lens names
At 07:31 PM 6/5/98 +0000, you wrote:
>> From: "David Foy"
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: David Foy david.foy@shaw.wave.ca
Subject: Re: [Rollei] Lens names
David Foy
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Coated vs non coated
Date: 25 Apr 98
Patrick Bartek
bartek@skylink.net
Newsgroups: rec.photo.misc
Subject: Re: Spiratone 400mm screwmount?
Date: Fri, 5 Jun 1998
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Multicoated lenses
Date: Tue, 09 Jun 1998
>
>
>Fred E. Dutton wrote:
>
>> I have six lenses for my view camera, all about 15 years old which I
>> am selling. A couple of them are clearly stamped multicoated but the
>> other four are not. They all have the same kind of purple tint to them
>> suggesting they are coated. The buyer wants to know whether they are
>> indeed multicoated. How does a person determine this? I haven't used
>> these lenses in ten years and simply cannot remember whether they're
>> multicoated or not although I think they are. Thanks for any
>> suggestions.
>
> Pragmatic test is best. Simply take a picture with your multicoated
>lens and one not multicoated at the same aperture, all other variable
>matched. See if you can see any difference. I doubt you can tell the
>difference in LF lenses ...maybe you can with a complicated 35mm zoom
>lens . It is just media hype...Best wishes... Ed Romney
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Multicoated lenses
Date: Tue, 09 Jun 1998
>Another good method is shooting a high contrast light source,
>such as the Sun. Non-multicoated or poorly multicoated lens
>will show large pieces of aperture shape flare.
>Something, U can even see it on the ground glass.
>
>
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Assessing Rolleiflex condition
At 02:25 PM 5/26/98 -0400, you wrote:
>
>I got my rolleiflex from Robert Pins just before the weekend
>and upon inspecting the lens I noticed one or two spots on
>the coating surface that refuse to go away using microfiber cloth
>and lens cleaner. Could that be fungus or is it some other defect
>of the coating? The bigger spot is between 1/64 and 1/32 of an inch.
>How much should I worry about it? I will be getting my test roll
>back from the lab tomorrow. The lens also has some fine cleaning
>marks.
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: ark@research.att.com (Andrew Koenig)
[1] Re: Pegging the Focus Ring for Infinity
Date: Thu Jun 18 1998
> Q: for shots at infinity, is it reasonable to assume that the
> focusing ring on the lens should be twisted to the mechanical
> stopping point corresponding to the infinity marking?
--Andrew Koenig
ark@research.att.com
http://www.research.att.com/info/ark
From: ark@research.att.com (Andrew Koenig)
Subject: Re: Pegging the Focus Ring for Infinity
Date: Thu, 18 Jun 1998
> Q: for shots at infinity, is it reasonable to assume that the
> focusing ring on the lens should be twisted to the mechanical
> stopping point corresponding to the infinity marking?
--Andrew Koenig
ark@research.att.com
Subject: Re: Why are big-glass wide angle lenses so slow aperture-wise?
Date: Sun, 21 Jun 1998
From: lesaus@aol.com (Lesaus)
[1] Re: "diffraction" problem? [Pentax 67]
Date: Sat Jun 27 1998
From: "David Foy" nomail@this_address.please
[1] Re: Uncoated lenses for color?
Date: Sat Jun 27 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Rollei
>know of an adaptor for that primo Schneider 150mm to Bay1 ? ;-} And what
>the heck is a "floating element" anyway?) However, a couple of eagles
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: why do lens costs differ so much? Re: Glass Manufacturers
Date: Wed, 08 Jul 1998
> What are the sources of the differences which justify the huge
> differences in price between lenses? between formats?
From: HRfoto@aol.com
To: rmonagha@post.cis.smu.edu
Subject: Re: why do lens costs differ so much? Re: Glass Manufacturers
From: Wai Lun Alan Chan wlac@cs.rmit.edu.au
To: rmonagha@post.cis.smu.edu
Newsgroups: rec.photo.misc
Subject: Re: Why are big-glass wide angle lenses so slow
aperture-wise?
>Greetings y'all ;-)
>
>Question about why wide angle lenses have sooo much glass for such slow
>apertures. Just doesn't seem logical when I try to think about it ;-) Help!
>
>I understand why a fast telephoto lens has to have a lot of glass, i.e.,
>an f/4 200mm lens has a 200/4 or 50mm of glass at the limiting aperture.
>An f/2 200mm lens would have to have more glass, as 200/2 or 100mm is
>nearly 4 inches across vs. 2 inches or 50mm for the f/4 version. A
>100mm f/4 would be 100/4 or 25mm at limiting aperture, and a 24mm f/4
>would have a limiting aperture circle only about 24/4 or 6mm across.
>
>Obviously, as the focal length gets larger, the lens aperture has to get
>larger to provide equivalent ratio'd lighting at the film plane from
>farther away. But shouldn't it work in reverse, so as you get closer to
>the film plane, the lens size gets smaller while delivering similar speed?
>
>So why does a 24mm F/2 lens have sooo much glass up front when the
>limiting aperture is evidently only 12mm? Or an 8mm f5.6 fisheye is
>bigger than the entire camera front, while the limiting aperture is only
>just over a millimeter, right? Why half a melon's worth of glass for a
>1mm sized limiting aperture?
>
>It doesn't seem logical that that extra glass is extending the angle of
>coverage, right, since a smaller aperture 24mm lens has the same
>coverage angles, just a whole lot less glass to get it. It is also
>covering the same 35mm film frame, so differences in coverage aren't an
>issue.
>
>In other words, telephoto lenses seem to be relatively "efficient" in
>that the big glass up front is fully used to deliver speed - aperture, so
>a 4 inch piece of glass corresponds to an f/2 200mm lens as expected.
>
>A normal lens is somewhat inefficient, with a 50mm f1.4 lens having maybe
>a 50mm front glass element (you expect f1 but get f1.4, but diaphragms in
>there too, so not tooo surprising ;-).
>
>But a similarly large piece of glass on a wide angle lens corresponds to a
>hugely inefficient system; a 50mm front piece of glass produces an f/2.8
>aperture on a 24mm, for example - 24/2.8= 8mm, versus the 50mm of glass
>up front, 625xPI vs. 16xPI or circa 35-40 times the area and weight etc. ;-)
>
>So why are wide angle lenses so seemingly inefficient and requiring such
>a huge piece of glass up front in order to provide a rather modestly
>sized limiting aperture usually just 5-10mm or so across?
>
>thanks in advance for clearing this up ;-) regards bobm
From: Anyone nospam@pacifier.com
To: Robert Monaghan rmonagha@post.cis.smu.edu
Subject: Re: Why are big-glass wide angle lenses so slow
aperture-wise?
Direct replies to: dpayne at pacifier dot com
From: dickburk@ix.netcom.com (Richard Knoppow)
[1] Re: Need Goerz info
Date: Mon Jul 13 1998
>Would one of the Goerz experts in the group fill me in on a "Syntor"?
>The one I have is marked "Goerz Syntor F6.8 U.S. Pat No 635472 Series
>Id No.6 Focus 12 IN No. 226300. It's a barrel with both "US" (2.9-256)
>and "normal" (6.8-64) f stops. Looks like single coating. Came in nice
>blue Goerz Am Optical Co box.
>Thanks in advance.
>Brian Downey
>
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: Arne Croell arne@sgi3.krist.uni-freiburg.de
[2] Re: Lens 'tarnishing'
Date: Mon Jul 13 1998
From: dickburk@ix.netcom.com (Richard Knoppow)
[1] Re: Damaged lens coating maybe???
Date: Mon Jul 13 1998
>I absentmindedly sprayed some PEC-12 on my 210 APO Schneider lens and
>wiped off a bunch of black stuff which may have been just the black
>paint on the lens barrel. The manufacturer of PEC-12 said it was
>probably just the paint but how does a person know if they have damaged
>the lens coating? Thanks
>
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: dickburk@ix.netcom.com (Richard Knoppow)
[2] Re: Lens 'tarnishing'
Date: Tue Jul 14 1998
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: Ron Wisner 72072.2763@CompuServe.COM
[2] Re: Lens 'tarnishing'
Organization: Wisner Classic Mfg Co., Inc.
Date: Tue Jul 14 1998
From: frjshuster@aol.com (FrJShuster)
[1] Beat Up Lenses - Perfect Pictures
Date: Sun Jul 12 1998
frjshuster@aol.com
From: "skgrimes" skgrimes@ma.ultranet.com
[1] Re: Lens Testing Accuracy Question
Date: Sun Jul 19 1998
From: rpn1@cornell.edu (Neuman-Ruether)
[1] Re: Light falloff?
Date: Mon Jul 20 1998
>In Pop Photo's Buying Guide (98/99) they use observations like "Light
>fall-off was gone by f/5.6 at 24 mm" (referring to 24-70 mm f/3.3-5.6 AF
>Sigma lens) or "there was no light fall-off at all at 50 mm and 70 mm"
>(referring to a 28-70 mm f/4 FA AF Pentax lens). I tried to find
>references to this term but have been unsuccessful. What does it mean?
>Is it good or bad?
ruether@fcinet.com
rpn1@cornell.edu
http://www.fcinet.com/ruether
[1] Re: Light falloff?
From: "Jim Williams" jlw@nospam.net
Date: Mon Jul 20 1998
>In Pop Photo's Buying Guide (98/99) they use observations like "Light
>fall-off was gone by f/5.6 at 24 mm" (referring to 24-70 mm f/3.3-5.6 AF
>Sigma lens) or "there was no light fall-off at all at 50 mm and 70 mm"
>(referring to a 28-70 mm f/4 FA AF Pentax lens). I tried to find
>references to this term but have been unsuccessful. What does it mean?
>Is it good or bad?
From: Mamiya645@aol.com
Subject: [Rollei] Rollei trivia
From: Stewart.Long@bcm-ltd.co.uk
Subject: re:cleaning Nikon lenses
Newsgroups: rec.photo.equipment.35mm
Subject: Re: sigma lens quality
Date: Thu, 23 Jul 1998
>Sigma is really bad, so try once and only once if you really have to.
>I'm a portrait photographer myself, and i tried sigma before. AF didn't
>work after the first night...then exchange for new one.
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Dirt inside lense?
Date: Mon, 27 Jul 1998
>
> My Pentax 50mm f/1.4 lens came with a small spec of dust in it also. I
> decided not to return it. I have made a few 11x14 enlargements from this lens
> and they are some of my sharpest prints. I doubt that a little spec of dust
> would affect your pictures. They eventually get little pieces of dirt in them
> anyway.... Keep the lens.... The guy at the store is telling you the truth.
>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Dirt inside lense?
Date: Tue, 28 Jul 1998
Date: Thu, 30 Jul 1998
From: Januar Rahadi jrahadi@ibm.net
Subject: Re: Preventing dust on the reflex mirror
Januar Rahadi.
>------------------------------
>Date: Thu, 30 Jul 1998 01:42:56 -0500
>From: Drew Chaplin
Subject: Tokina AF 20-35/2.8 (my experience)
Date: 2 Jul 1998
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Lens scrubbing?
Date: Tue, 04 Aug 1998
>Let's say someone had an old lens that had dried crud on one of the surfaces
>(probably old fungus now fossilized). Let's also say that the owner wanted to
>try a fine rubbing compound to remove and v.gently re-polish the surface. What
>compound would be recommended? Something used by the astronomy lens grinder's
>in the last step? Or?
>
>Thanx for any and all suggestions.
>
>- Chris
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: __ Fungus in lens
Date: Thu, 13 Aug 1998
From: " Dante A. Stella" dante@umich.edu
Subject: Re: "Cleaning marks"
Date: Mon, 17 Aug 1998
Newsgroups: rec.photo.marketplace
Subject: Re: "Cleaning marks"
Date: Tue, 18 Aug 1998
H�kan Gunnarsson
G�teborg, Sweden
From: ewindell@psci.net (Gene Windell)
[1] Re: When to use lens hood?
Date: Sun Sep 06 1998
>>>I understand a lens hood can increase contrast and reduce flare. So,
>>>should you use a lens hood all the time? Or just when shooting in the
>>>outdoors?
From: Tsun Tam ttam@cybernex.netq
Subject: Response to DIY lens test of scratched Hasselblad 50mm C T*
Date: 1998-08-24
From: James Chow jchow@atom.isl.melco.co.jp
Subject: Response to DIY lens test of scratched Hasselblad 50mm C T*
Date: 1998-08-24
From: Colm Boran cboran@visteonet.com
Subject: Scratched 50mm Distagon Update
Date: 1998-08-26
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Sunrises & flare
Date: 16 Aug 1998
>Hi, I am planning on shooting sunrises on the East coast in a week. Whenever I
>have done this before, some of my pics have resulted in flare. I should state
>that the Pics are from the same location and the only variable is time (2 to 5
>min. apart) sometimes flare sometimes not. The sun does not change position
>that much in this amount of time. I am planning on using ektar 25 but should
>I use a faster film? Also I do use a a lens shade but this does not seem to
>make a difference. Do you have any suggestions? Thanks for any help,
> Gene
Newsgroups: rec.photo.equipment.35mm
Subject: Re: ar coating damage question
Date: Fri, 28 Aug 1998
Michael A. Covington / AI Center / The University of Georgia
http://www.ai.uga.edu/~mc http://www.mindspring.com/~covington
From: tired.of.spam@nospam.com (Rudy Garcia)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Pitting on lens?
> I just bought a used Nikon 50mm f.18 AF and noticed what I thought was dirt or
> something on the lens that is nearest the shutter. Got out my lens cleaning
> fluid and microfiber cloth to clean it and found that the lens apparently has
> some pitting on it. Even though it apprears to be minor should I return it or
> will it not cause any problems? Any info on this would be grealy appreciated.
>
> Thanks
> Zack
> N8FNR
Use address below for Email replies. Address on Header is bogus to defeat
AutoSPAM.
________________________________
Rudy Garcia
Newsgroups: rec.photo.equipment.35mm
Subject: Arrrgh... fungus
Date: Sun, 30 Aug 1998
C h r i s t o p h e r S. O w n (847) 332-5316
http://pubweb.nwu.edu/~cso559
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Arrrgh... fungus
Date: Mon, 31 Aug 1998
> First, expose it to strong sunlight. That should kill the fungus. Then
> use the lens. If it appears that the fungus has no effect, don't worry
> about it.
C h r i s t o p h e r S. O w n (847)
332-5316
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Arrrgh... fungus
Date: 1 Sep 1998
Boz Dimitrov
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How to take care of camera equipments?
Date: Wed, 02 Sep 1998
James
> Hi all,
>
> I own SLR equipments (Elan II with 28-105 USM lens) and use them occasionally
> (only once a month or longer apart than that). I live in the South and
> usually keep them in the camera bag. Is it possible to get fungus for the
> camera body or lens? How can we prevent fungus? Is the silica gel useful to
> prevent it? Any other concerns for the care of this rarely-use equipments? Any
> positive inputs would be greatly appreciated.
Subject: Re: How to take care of camera equipments?
Organization: United System Solutions Inc.
Date: Wed, 2 Sep 1998
Stephen M. Dunn (SD313), CNE, ACE
steved@ussinc.com
----------------------------------------------------------------------------
Senior Manager United System Solutions
Inc.
104 Carnforth Road, Toronto, ON, Canada M4A 2K7 (416) 750-7946
x251
Date: Thu, 3 Sep 1998
From: "John F. Butler Jr." jbutler@pond.net
Subject: Silica gel update
Eugene, OR
From: jamesgl@gte.net (James Gluckin, M.D.)
[1] Have you had luck in removing Fungus from lenses
Date: Sat Sep 12 1998
******
Web Page http://www.eyecareforyou.com
From: "Michael A. Covington" covington@mindspring.com
[1] Re: Have you had luck in removing Fungus from lenses
Date: Sat Sep 12 1998
From: "K and J Darling" thedarlings@ix.netcom.com
[1] Re: Lens fungus: Home made dry cabinet?
Date: Sun Sep 20 1998
niyen@my-dejanews.com wrote
> Hello all,
>
> I live in a hot and humid country and lens fungus is a serious problem.
> Buying a commercial dry cabinet is unfortunately, an expensive alternative.
> Someone from this discussion group mentioned about using a 60- watt light
> bulb and a wooden cabinet. It seems to be an ideal solution as the heat from
> the bulb would dry out the air's moisture. However, wouldn't the heat harms
> the lens? Could someone explain more on how it works? How is the cabinet
> built? Do you need to leave a space for air circulation and so on? Any
> information is greatly appreciated. Thank you.
From: "Michael A. Covington" covington@mindspring.com
[1] Re: Lens fungus: Home made dry cabinet?
Date: Sun Sep 20 1998
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Lens fungus: Home made dry cabinet?
Date: Mon, 21 Sep 1998 05:57:38 GMT
KY Mak
-----------------------------------------------------------
My photography page:
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Lens fungus: Home made dry cabinet?
Date: Sun, 20 Sep 1998
AMMUNITION COMPONENT BOZ MK2
MOD O 982443-8 EEI
From: David Foy david.foy@shaw.wave.ca
To: rollei@mejac.palo-alto.ca.us
Subject: RE: [Rollei] Rollei Sl66 Lenses
MarkeTactics(TM)
Newsgroups: rec.photo.equipment.35mm,rec.photo.equipment.misc,
Subject: Re: question about mirror lenses
> >Paul Johnson Paul@treetop.demon.co.uk wrote:
>
> >>These days mirrors are coated in aluminium, which doesn't tarnish.
> >
> >Aluminum oxidizes just as quickly as silver tarnishes.
>
> Actually aluminium oxidises almost instantly. However AlO2 (aka
> "carborundum") is transparant and very hard.
>
> >Optical front surface mirrors generally have a protective coating of silicon
> >dioxide or similar material on them.
>
> I.e. a layer of glass? Odd. I'm not saying you are wrong, just
> wondering how they get it on. Metals can be done by vapour, but I
> didn't know glass would vapourise that easily or deposit that evenly.
Newsgroups: rec.photo.misc
Subject: Re: Lens Hood or Shade
Date: Wed, 30 Sep 1998
> As a suggestion, you should always use a lens hood as it cuts down flare,
> and sidelight.
> John
--
Chris Buechner
WILDfire [ photography ]
Sydney, Australia
From: "Kotsinadelis, Peter (Peter)" peterk@lucent.com
Subject: RE: [Rollei] Rollei lens and fungii
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Chipped Lens
>I have purchased a Rolleicord Vb in rough condition. At the time I did
>not notice a small chip in the lens. Investigating I found that it is
>on the edge of the second element ? (the rear one of the front assembly).
>The chip extends through the whole thickness of the lens element, cuts in
>approx 0.5mm and occupies just under 4mm of the circumference at the widest
>point.
>
>I suspect that someone tried to open the front assembly to clean the lenses
>and caused the damage with a tool.
>
>My questions:
>
>1) I was intending to paint the exposed edge with a matt black to minimise
>reflection / flare. Is this appropriate, or is there a better fix ?
>
>2) What is the likely effect of this fault? My lens theory is not up to
>knowing how important the outer edge will be for image quality.
>
>Thank you
>
>--
>Richard Urmonas
>rurmonas@senet.com.au
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: toby
Subject: Re: [Rollei] Chipped Lens
>On Sun, 4 Oct 1998, Richard Urmonas wrote:>
> My questions:
>
> 1) I was intending to paint the exposed edge with a matt black to minimise
> reflection / flare. Is this appropriate, or is there a better fix ?
>
> 2) What is the likely effect of this fault? My lens theory is not up to
> knowing how important the outer edge will be for image quality.
Toby
From: Gene Woolridge gene360@erols.com
To: hasselblad@kelvin.net
Subject: Re: wobbly lens
From: Simon Stevens simon@wizard.net
Subject: RE: hasselblad V1 #327
Re: wobbly lens
Camera Craftsman
(703) 548-7548
http://www.wizard.net/~simon/
From: Eric Goldstein egoldste@bu.edu
Subject: [Rollei] Good MF Portrait Cameras
> I have a late model 124G (serial no. 3041991) with the Yashinon lens (ser
> no. 1112501). The lense is of 4 element 3 group design and as far as I can
> tell, it is coated (colored light reflections).
>
> Lens is good for portraits (softness hides skin blemishes) with good
> contrast. I prefer to use this camera for 'not so close' portraits over
> the Planar or Xenotar (both for the 6X6 SLR Rolleis) as the latter lenses
> are simply too 'unforgiving'. Older folks with age spots on their faces
> and hands look better shot with 124G.
From: Doug bobafett@pe.net
[1] Re: Fungus
Date: Fri Oct 23 1998
>
> >You know those little
> >silica gel sacks labeled "desiccant"???
>
> >Good Luck finding these little packs.
>
> ...You can probably obtain a silica gel sack product at any Musical Instrument
> Retailer. They are made to place in the cases of wooden instruments...guitars,
> violins, etc.
>
> JWM
From: "toby" zdftokyo@gol.com
[1] Re: Fungus
Date: Fri Oct 23 1998
zdftokyo@gol.com or remove SPAMJAM to reply
From: "St�phane Leman-Langlois" stephane.leman.langlois@utoronto.ca
[1] Re: Fungus
Date: Fri Oct 23 1998
From: "T.O. Galloway" tgall@erols.com
[1] Re: Fungus
Date: Fri Oct 23 1998
Newsgroups: rec.photo.digital,rec.photo.misc
Subject: Re: How to fix a scratched transparent lens face?
Date: Sun, 04 Oct 1998
DO NOT POLISH A SCRATCH OUT OF A LENS!!!!!!!
It will distort the lens surface and ruin its focus.
It will destroy the lens.
From: stefan stefan9@ix.netcom.com
Subject: Response to Marks on lens glass
Date: 1998-10-18
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Fungus
Date: 20 Oct 1998
>I recently bought a lens over the net. The lens' front and rear elements were
>crystal clear. I did notice that if I shined a penlight through the front
>element that I could see lots of dust and two very distinct parallel lines (not
>perfectly straight but nonetheless parallel) that if I could best describe it
>looked like someone scratched two very fine lines in one of the elements with a
>sharp pin (roughly the entire length of the glass and 1 mm apart from each
>other. With the light it actually could look like someone drew the parallel
>lines with very fine dust. It is hardly noticeable if I held the lens up to
>natural sunlight. In fact, it was only visible when using the penlight. The
>lens is indeed a user and the condition of its barrel suggests that although
>the glass seems pretty clean.
From: herphoto@aol.com (Herphoto)
[1] Re: Nikkor Lens Dust!!!!!
Date: Tue Nov 03 1998
From: andrsnsm@aol.com (Andrsnsm)
[1] Re: Nikkor Lens Dust!!!!!
Date: Tue Nov 03 1998
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Nikkor Lens Dust!!!!!
Date: Sun, 01 Nov 1998
> Hi.... everybody
> I have a 24-120mm.... very sharp...... but I see lens dust inside the lens
> element...... I thought it is because it is not a professional lens...
> But few days ago..... I bought the new Nikkor ED 80-200mm F2.8,
> Same thing happen again....!!! That dealer gave me FOUR lens to
> choose.... ALL of them are new and has dust in it..!!!!!!! Non is
> perfect..!!!
> That saleperson even laugh at me... said I'm crazy..!!!!
> NOW I believed it is normaly to have small tiny dust in Nikkor lens....
>
> Has anybody have the same experience......???
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Nikkor Lens Dust!!!!!
Date: Sun, 1 Nov 1998
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Nikkor Lens Dust!!!!!
Date: Sun, 1 Nov 1998
Michael A. Covington / AI Center / The University of Georgia
http://www.ai.uga.edu/~mc http://www.mindspring.com/~covington
From: "Michael A. Covington" covington@mindspring.com
[1] Re: Scratched lens fix-up
Date: Sun Nov 08 1998
Michael A. Covington / AI Center / The University of Georgia
http://www.ai.uga.edu/~mc http://www.mindspring.com/~covington
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] lens fungus
>I recently bought a Rolleicord which has some small fungus marks on the
>viewing and taking lenses. Is there any simple way I can eliminate this
>stuff?? It does not seem to have much noticeable effect on the image, but
>I'm afraid it will spread.
>
>Russ Rosener
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: Jeff slikrock@worldnet.att.net
[1] NIKON lens with FLAWS???
Date: Mon Nov 09 1998
From: rdd5tk@aol.com (RDD5TK)
[1] Re: NIKON lens with FLAWS???
Date: Tue Nov 10 1998
From: bg174@FreeNet.Carleton.CA (Michael Gudzinowicz)
[1] Re: Schneider 90mm f8
Date: Fri Nov 27 1998
>I have a Schneider Super Angulon 90mm f8 that I recently purchased a new
>shutter for from Schneider. All of a sudden it's not as sharp as
>before. I was told that the lens should be "centered". Is this
>something I can do myself?
From: Tony Keil adkeil@wantree.com.au
Subject: [Rollei] edge separation/lens delamination
Tony Keil
From: wlac@cs.rmit.edu.au (Wai Lun Alan Chan)
[2] Re: Sigma Haze was (lens manufacturers)
Date: Wed Dec 02 1998
>Shine a torch through the Sigma, and see if you can pick up a haze on one of
>the elements. If so, you'll have to get that lens group replaced ($$$). No
>guarantee it wouldn't happen again with the new lens group in time,
>however... that's the price of owning Sigma lenses.
=== regards, http://yallara.cs.rmit.edu.au/~wlac/ ===
=== Alan Chan wlac@cs.rmit.edu.au ===
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] edge separation/lens delamination
>Greetings Fellow readers
>
>The usual advice proffered to intending purchasers of Rollei TLR's includes
>inspecting the Rolleiflex taking lens for edge separation or lens
>delamination. Often the advice or inference seems to be to pass these
>cameras by.
>
>I am interested in hearing from list members just how critical this is, or
>to what extent can edge separation be tolerated (eg 2mm or 3 or 4 ...all
>around the circumference is OK/not OK) or if it is OK are there any
>qualifiers (eg as long as not shooting at widest apertures into bright
>light source etc). Is edge separation on the front doublet of a Rolleiflex
>2.8/80mm E or F planar more or less cause for concern than edge separation
>affecting the rear doublet of a Rolleiflex 3.5/75mm E or F planar?
>
>The only posting that I've been able to find that specifically addresses
>image quality suggested that the difference between a Rolleiflex having
>edge separation (degree unspecified) and one without was "dramatic".
>
>People on this list must be using cameras that have varying degrees of
>separation. On my 2.8/80mm planar with 3-4 mm edge separation, as long as
>I shoot at f5.6 and below and avoid strong lights either in the picture
>area or outside it (ie sun) there doesn't appear to be a problem. If I
>don't do this then blue flare highlights occur in the transparencies.
>
>I'd be really interested in the experience of others.
>
>Regards
>Tony Keil
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: lawrenceNOSPAM@hoflink.com (WINDOWS 2000 USER)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: In defense of the Hasselblad way
Date: Mon, 21 Dec 1998
After 20 years of Hasseblad ownership, I am dismayed at the new
construction and the astronomical pricing to boot! I enjoyed my Blad gear
but don't lead anyone into thinking that they are perfect. I had to have
routine maintainence and a number of nagging repairs made to a number of
lenses. My brand newe 350CF came in with a 1/16" air bubble in the
second
element in from the front!!!! What kind of quality control is that, I ask
you???? (Hassey in New Jersey replaced the entire lens immediately and
apologized). The fact is that many other optic manufacturers are
making
glass of equal quality to Zeiss. This does not reduce the mystique or
allure of German optic skill, but rather makes the statement that there
are other equally superb optics available today. Ultra modern computer
technology makes this all possible! Computer designed and driven
machinery grinds precision glass now, not little silver haired men
laboring in dimly lit laboratories. I respect your right to adore
Hasselblad and its reputation. However, there is a new milenium upon us
and as Bob Dylan sang, 'the times, they are a changin'.
From: pwright pwright@cyberus.ca
[1] Re: Cleaning a lens
Date: Mon Feb 08 1999
Peter
Newsgroups: rec.photo.equipment.medium-format
Subject: Lens Coating Defects
Date: Wed, 27 Jan 1999
Date: Tue, 16 Mar 1999
From: Robert McLaughlin Lckyrwe@discover.net
Subject: Tiny bubbles [v04.n306/12]
TINY BUBBLES
>After purchasing the new Nikon 80-200 AF-S Silent Wave lens, I have made an
>observation. Upon close examination of the lens elements by holding the lens
>up to a light source and looking through, I am seeing excessive dust/lint on
>the internal elements and also what appears to be a tiny bubble on one of the
>elements.
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Solutions for Fungus
Date: 4 Mar 1999
Newsgroups: rec.photo.equipment.35mm,rec.photo.equipment.large-format
Subject: Re: FUNGUS!
Date: Fri, 19 Feb 1999
>It has finally happened. I think. Fungus in a lens and in a viewfinder. To
>the point: assuming the lens and finder can be opened, can fungus be
>removed? Does fungus 'etch' glass or coated surfaces?
>
>...and is fungus a contagion? In other words, if I have other equipment
>stored in the same place, can it 'catch' fungus from the infected
>hardware?
>
>This is a real bummer.
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Very Fine Scratches on Lens - How bad is this?
Date: Tue, 27 Apr 1999
>Today, when cleaning the front element of my lens, I was horrified to find
>that there were three very fine scratches across the center of the lens.
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Silica Gel info - toxicity
Date: Sun, 16 May 1999
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Pigs in Pokes - Commercial Ektars
Date: Sun, 16 May 1999
Occasional small bubbles are very common in dense barium crown glass,
which is what the front element is made of. It has no effect on
performance whatever. Beware of bubbles in the rear element, they may
actually be indications of problems with the cement.
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] What caused this lens damage?
>I saw a nice camera in a store window today. However I noticed that there was
>a series of small reflections where the light was catching the bottom of the
>lens. Initially I thought it was lens seperation of some kind, but after
>getting home it occured to me that there were several rows of these and they
>must have been from the edge of each lens. So the question is what could have
>happened to it. The camera did not appear to have been dropped. The salesman
>said it had a non-functional shutter so perhaps this is another clue.
>
>My main interest in knowing is that the price is good, and if the lens damage
>is easily fixed or can be ignored I would consider buying it.
>--
>Richard Urmonas
>rurmonas@senet.com.au
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Thu, 8 Jul 1999
From: "Alan Moore" amoore@uniserve.com
Subject: [NIKON] New Cokin filters
Alan Moore,
Victoria BC
Canada
Date: Sat, 10 Jul 1999
From: "John F. Butler, Jr." jbutler@statecollege.com
Subject: [NIKON] humidity
Newsgroups: rec.photo.misc
Subject: Re: Lens bubbles
Date: 12 Jul 1999
Newsgroups: rec.photo.equipment.35mm,rec.photo.misc
Subject: Re: What kind of DEFECTS are "normal" in a brand new premium
lens?
Date: Fri, 30 Jul 1999
>I just bought a brand new Canon 28-70 f 2.8 "L" premium zoom lens. This is
>a premium lens and cost over $1000. The problem is that the lens that
>arrived here (I bought via mail order from B&H) has a minute flaw in the
>anti-reflective coating of the lens surface. There is a pinhole-shaped
>"nick" about 7 degrees off the center axis that is clearly visible as a
>bright spot when looking at the lens surface (which has a violet hue due
>to the coating) from an angle.
>
>This is a new lens, and my first among the "L" series. My questions:
>
>- are these kinds of defects "normal" in a premium lens?
>
>- should I tolerate this or send the lens back for an exchange (which is
>quite a hassle)
>
>- will this affect image quality at all?
>
>I am usually quite good at keeping my lenses clean and in good shape. I
>always use some filter as a lens protector. It just bugs me that my most
>expensive lens would come with a visible defect from the beginning.
>
>Thanks for any responses,
>Michael Franz
Newsgroups: rec.photo.equipment.35mm,rec.photo.misc
Subject: Re: What kind of DEFECTS are "normal" in a brand new premium
lens?
Date: Fri, 30 Jul 1999
>I just bought a brand new Canon 28-70 f 2.8 "L" premium zoom lens. This is
>a premium lens and cost over $1000. The problem is that the lens that
>arrived here (I bought via mail order from B&H) has a minute flaw in the
>anti-reflective coating of the lens surface. There is a pinhole-shaped
>"nick" about 7 degrees off the center axis that is clearly visible as a
>bright spot when looking at the lens surface (which has a violet hue due
>to the coating) from an angle.
>
>This is a new lens, and my first among the "L" series. My questions:
>
>- are these kinds of defects "normal" in a premium lens?
>
>- should I tolerate this or send the lens back for an exchange (which is
>quite a hassle)
>
>- will this affect image quality at all?
>
>I am usually quite good at keeping my lenses clean and in good shape. I
>always use some filter as a lens protector. It just bugs me that my most
>expensive lens would come with a visible defect from the beginning.
>
>Thanks for any responses,
>Michael Franz
Date: Wed, 18 Aug 1999
Subject: Re: [Rollei] Lens Bubbles
>A camera repairman up here in Alaska once told me that the Xenar taking lens
>in my Automat M/X must be a very fine one since it has a bubble in it. I
>haven't noticed any distortions because of it. I also have a huge (around
>4" dia.) Zeiss enlarging lens that has several bubbles. Another fine one?
>
>Does anyone have the scoop? (Careful, don't burst my bubble!)
>
>Thanks!
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: Andre Calciu a.calciu@anent.com
Subject: Re: [Rollei] Lens Bubbles
> A _lot_ of bubbles or big bubbles in a lens suggest the maker didn't have very
> good QC or was too cheap to reject the glass. One or a couple of small ones are
> without optical effect and meaningless.
Newsgroups: rec.photo.equipment.35mm,rec.photo.misc
Subject: Re: What kind of DEFECTS are "normal" in a brand new premium
lens?
Date: Mon, 02 Aug 1999
> The problem is that the lens that arrived here (I bought via
> mail order from B&H) has a minute flaw in the anti-reflective
> coating of the lens surface. There is a pinhole-shaped "nick"
> about 7 degrees off the center axis that is clearly visible as
> a bright spot when looking at the lens surface (which has a
> violet hue due to the coating) from an angle.
From Leica User Group:
Date: Sun, 19 Sep 1999
From: Jem Kime jem.kime@cwcom.net
Subject: RE: [Leica] QA/QC
rec.photo.equipment.35mm
From: spam-abuse@worldnet.att.net (Tom)
[1] Re: The Dumbest Thing in Your Bag
Date: Tue Sep 28 1999
I keep at least one "Super absorbant incontenence pad" in each of my
camera bags for relatively long term equipment storage. They are
filled with huge amounts of silica gel compared to what you get at a
camera store, are in a very convenient "flat-pack," are much cheaper,
and very easy to get.
Washington, DC
Newsgroups: rec.photo.equipment.35mm
Subject: Re: What is contrast?
Date: Tue, 05 Oct 1999
Washington, DC
From: ejkowalski@aol.com (Ejkowalski)
[1] Re: dust particles
Date: Fri Oct 29 1999
>there are dust particles on the inside of my focusing screen.
>how do i remove the focusing screen? what tool do i use?
>my camera is a Canon EOS 500 (Rebel XS).
>
>Jason
From: wardcheese@aol.com (WardCheese)
[1] Re: cleaning fungus off lens
Date: Tue Nov 30 1999
From: Gary Sanford sanford1@sprynet.com
[1] Re: How do you prevent fungus
Date: Sun Dec 19 1999
>Where do you get silica gel packets?
Gary Sanford
From: R. Saylor rlsaylor@ix.netcom.com
[1] Re: How do you prevent fungus
Date: Sun Dec 19 1999
>then, how can you pack those silica gel sand ? What is the bag that you
>use?
From: "Matt O" nojunkspam@nojunkspam
[1] Re: How do you prevent fungus
Date: Sun Dec 19 1999
> What causes fungus in lenses? Is there a reccomended way to store your
> lenses to avoid getting fungus?
From: thedrks791@aol.com (Thedrks791)
[1] fungus
Date: Tue Dec 21 1999
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Spherical Aberation
Date: Thu, 14 Oct 1999
Newsgroups: rec.photo.equipment.large-format
Subject: Re: cleaning fungus off lens
Date: Wed, 01 Dec 1999
>I've seen lenses for sale with fungus on the elements, can this be
>successfully cleaned off and how?
>
>Clayton Tume
From: Doug Cooper visigoth@echonyc.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Tiny Bubble
Date: Sat, 22 Jan 2000
From: Nikon Cameras NikonCameras@asean-mail.com
Subject: Re: dust in lenses
Date: Sun, 06 Feb 2000
From: "Gary N. Wood" gwood@comabi.mv.com
Subject: Re: [NIKON] Lens Fungus Repair?
>Anyone have experience in what's involved in cleaning fungus in a lens or
>TC. I have a chance to pick up a lens in good condition (other than some
>fungus) for a great price. However, I'm not sure about the cost to clean
>out the fungus or if it would be a reoccuring problem.
From: ejkowalski@aol.com (Ejkowalski)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Scratch on lens
>Saw a used 70-200/2.8 EF for a good price. only problem: The front-lens has
>a small, tiny scratch on it (half an inch - hardly to see).
>
>Does this effect the quality of the lens in any way?
>
>Thanks
>
>N.
>
Date: Sun, 13 Feb 2000
From: Marc James Small msmall@roanoke.infi.net
To: rollei@mejac.palo-alto.ca.us
Subject: [Rollei] OT: Leica acquisition question
>Be advised that you should view any older Leica lens through a bright light
>source at wide open aperture to determine the degree of fogging. It is
>likely to have some. I understand that this resulted from the type of
>lubricant employed by Leitz.
msmall@roanoke.infi.net
Date: Sun, 13 Feb 2000
From: steven arterberry arterberry@mindspring.com
Subject: Re: [Rollei] Leica acquisition question
Date: Sun, 13 Feb 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Leica acquisition question
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Thu, 11 Nov 1999
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] New stuff (2.8C)
> The finger prints may be etched into the coating. The oil from fingers
> has some acid in it which can etch both coatings and glass. Check with a
> loupe and strong light to see what is there.
Date: Thu, 11 Nov 1999
From: Roland Schregle schregle@ise.fhg.de
Subject: Re: [Rollei] New stuff (2.8C)
....
Roland Schregle
Fraunhofer Institute for Solar Energy Systems
Date: Thu, 11 Nov 1999
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] New stuff (2.8C)
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: dickburk@ix.netcom.com (Richard Knoppow)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Pinholes in lens
>Hi,
>
>At a photo flea market, I acquired a Schneider Symmar 210/5.6 for
>a very low price. The problam that it has is that there are about
>2 dozen randomly scattered pinprick marks on the the rear cell. =
>
>I took the rear cell apart, thinking that the problem was in the
>airspace between the cemented doublet and the single lens. It
>seems that the pinpricks are between the cemented doublet.
>
>What are these pinpricks? Are they fungus? If they are fungus,
>will prolonged exposure to sunlight or ultraviolet light get rid
>of the problem.
>
>Any information or help would be greatly appreciated. Otherwise
>the lens is impeccable as is the Synchro-Compur Shutter whose
>speeds are right on.
>
>Thanks in advance.
>
>Regards,
>Bogdan
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Date: Mon, 27 Dec 1999
From: Jim Stewart jstewart@jkmicro.com
To: hasselblad@kelvin.net
Subject: Re: C Lenses and Personal Preferences
From: "Simon Watkins" siwatkins@madasafish.com
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Lens question, cleaning marks/scratches??
> I would like opinions on whether cleaning marks, scratches on the front element
> of a lens affects image quality? I have seen a number of ads like this one:
>
> "Front element has some noticeable marks/scratches on it which DOES NOT
> affect picture quality, hence the lowish price."
>
> Which is currently on one of the rec.photo URLs.
>
> Opinons? I am not trying to start a war here but if a person could save a few
> bucks on a lens why not?
>
> Thanks in advance for any Info.
From: "Keith (R.K.) Berry" keith_r.k.berry@virgin.net
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Lens question, cleaning marks/scratches??
Keith Berry (Birmingham, England)
Date: Tue, 21 Mar 2000
From: InfinityDT@aol.com
Subject: Re: Field Curvature
Date: Mon, 27 Mar 2000
From: Sandy Schaffell oakview2@earthlink.net
To: hasselblad@kelvin.net
Subject: Re: hasselblad V1 #827
I would certainly ask Hasselblad about the 40mm black flakes, but if the
lens works as you want it, why bother? As to the 150mm. If it doesn't
suit you then sell it or learn to work with it. It could be that the
elements are out of line. You won't know until you have it checked on a
bench by an authorized Hasselblad repair person. In your position, I
would certainly do that.
From: James Meyer notjimbob@worldnet.att.net
Newsgroups:
rec.photo.equipment.medium-format,rec.photo.help,rec.photo.advanced,rec.photo.mi
sc,rec.photo.help
Subject: Re: Lens elements separating -- how serious?
>I have a 250mm Mamiya-Sekor Z lens in which it appears that the front
>element is separating from the second glass element. I can see a thin
>strip of color around the very outer edge of the lens -- bluish with a
>very thin edge on the inside that seems white. It extends about halfway
>around the circumference of the lens and is about 0.5mm wide.
>
>What effect will this have on the image quality of the lens?
>If there
>is an adverse effect (I can't imagine there would be a positive one),
>would it be diminished by stopping down?
>What is the likelihood that it will become progressively worse?
>A repair would seem to involve ungluing the lens elements involved, and
>then re-cementing them.
>Would it be cheaper to repair it, or should I
>replace the lens? If repairs are indicated, who in the U.S. can do it?
Date: Tue, 4 Apr 2000
From: "Roland Vink"
roland.vink@aut.ac.nz
Subject: Re: 105/f2.5 dust problem?
> I don't understand which is the "large" elements you're referring to
> I haven't really thought it about it until now, so was this repair
> guy right? I heard a rumor that the "air" between the lenses is pure
> nitrogen (I can't imagine life growing in that). And does it effect
> quality that much?
> After reading the threads on dust in the 105/f2.5, I was wondering how
> dust gets into a lens? I haven't checked my lenses yet but I will very
> soon.
Newsgroups: rec.photo.equipment.medium-format
From: radiojon@means.net
Subject: Re: Dust on internal lens surfaces
> I been looking at used Mamiya RB67 lenses. Some have a considerable amount
> of dust on the internal lens surfaces. How does this dust get there and what
> can be done about it? How bad does it have to be before it affects image
> quality?
From: dcolucci@aol.com (DColucci)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Dust on internal lens surfaces
From: Bjorn Rorslett nikon@foto.no
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Blue Ghosting around image?
> I just had a Digital Pegasus Print of a picture I took. It is a river with
> fog rolling off the water in the morning. In the scene there are a few
> branches that appear to have a somewhat blue ghosting around them.
> Everything else is fine. Nothing major, but I hope to sell it sometime. I
> had two diffrent size copies made of it and it still shows. The place where
> I had it done had no explaination of this. Does anyone know what this may
> be?
>
> I was using a 35mm camera
> I was using a somewhat cheap tripod and a cable release
> I was using Fuji Velvia film
>
> Could it be the Pegasus Print output?
> Would very small wind movements do it?(although it was very eary am and the
> air was still, I think)
> Anything else?
>
> Thanks
Bjorn Rorslett
Visit http://www.foto.no/nikon for UV Colour Photography and other
Adventures in Nature Photography
Date: Tue, 21 Sep 1999
From: Andre Calciu a.calciu@anent.com
Subject: Re: [Rollei] Lens Repair
> My 3.5F Planar has a what looks like a very small gouge on one of the inner
> surfaces of the taking lens. I fear it is causing a bit of flare. Aside from
> the gouge, the lens is pristine. I have read that carefully applied India
> ink can repair such damage. Does anybody know of a technician that will
> perform this service? Any suggestions would be greatly appreciated.
Date: Tue, 21 Sep 1999
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Lens Repair
>My 3.5F Planar has a what looks like a very small gouge on one of the inner
>surfaces of the taking lens. I fear it is causing a bit of flare. Aside from
>the gouge, the lens is pristine. I have read that carefully applied India
>ink can repair such damage. Does anybody know of a technician that will
>perform this service? Any suggestions would be greatly appreciated.
The Focal Point
John Van Stelten
1017 South Boulder Road
Suite E-1
Louisville, CO 80027-0027
Tel.- 303-665-6640
Fax - 303-665-3803
http://www.411web.com/F/FOCALPOINT/
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 22 Sep 1999
From: Bob Shell bob@bobshell.com
Subject: [Rollei] "Hot" lenses
> Radioactivity in the first generation of hot lenses c. 1941-1955 is a
> by-product of imperfect refinement of the monazite sands used to provide
> the rare earths. There are quite a few 'hot' rare-earth first-generation
> lenses, though it would take me a while to find the reference, and
> certainly, some of them were terrestrial: it has been suggested that the
> double shutter in the Voigtlaender Prominent was because the 50/1.5 Nokton
> -- the first new civilian rare-earth lens, as far as I know -- was 'hot'
> and could fog the film, though equally, this may simply have been extra
> insurance for light-trapping. Intriguingly, some Apo-Lanthars are 'hot' and
> others aren't, presumably reflecting different sources of lanthanum (or
> improved refining techniques from a single source). From recollection,
> these first-generation lenses were gamma-particle emitters, possibly with
> some beta (I'm not sure about the latter).
>
> Radioactivity in the second generation of lenses was down to the use of
> cerium to bleach iron salts in the glass; (colourless) ferrates are stable
> in glass solution. Once again, the purity of the cerium was questionable.
> These are alpha-particle emitters, which ain't normally a problem -- even a
> lens-cap stops the particles, as does a few cm of air -- but it's not a
> good idea to use the lens as a telescope eye-piece, as some did. These
> second-generation lenses stretched well into the 1960s; again from memory,
> at least one of the standard Takumars was 'hot'.
Date: Mon, 7 Feb 2000
From: Austin Franklin austin@darkroom.com
Subject: RE: 30mm F-Distagon Repairs
From: chun_in@my-deja.com
Newsgroups: rec.photo.equipment.35mm,rec.
+ photo.equipment.medium-format
[1] Re: leica or move up to medium format?
Date: Mon Apr 17 2000
Chun In Martinez
Date: Sun, 28 May 2000
From: "Bob Shell" bob@bobshell.com
Subject: Re: [CONTAX] Lens Repairin
Date: Tue, 6 Jun 2000
From: Alan Yeo nature_sg@yahoo.com
Subject: Re: [NIKON] Re: Quality
Date: Sat, 10 Jun 2000
From: "Bob Shell" bob@bobshell.com
Subject: Re: [CONTAX] "Purple" Smudge on mirror
Date: Mon, 12 Jun 2000
From: Alan Yeo nature_sg@yahoo.com
Subject: Re: [NIKON] Air Bubble In Lens
> Dear Guys,
> I think I've just discovered a small air
> bubble on the 2nd last
> element of my lens. It is a rather small bubble, abt
> 1mm in size. Will tt
> affect picture quality? Will Nikon replace the lens
> for such defects?
>
> Eugene.
Date: Mon, 10 Jun 1996
From: "Eugene Phua" phuaweh@cyberway.com.sg
Subject: [NIKON] Air Bubble In Lens
Date: Thu, 29 Jun 2000
From: "Dan Post" dpost@triad.rr.com
Subject: Re: [Leica] Re: impurities in lens
From: "William Robb" wrobb@accesscomm.ca
Date: Mon, 3 Jul 2000
Subject: Re: Aspherical Lenses and Distortion
Date: Wed, 12 Jul 2000
From: "Roland Vink" roland.vink@aut.ac.nz
Subject: Re: Lens review questions
Newsgroups: rec.photo.equipment.35mm
Date: Mon, 10 Jul 2000
Subject: Re: Lens Damage Test?
>On Thu, 6 Jul 2000 09:55:58 -0700, jim.NOSPAM@jtmiller.com arranged specific
>electrons to say...
>>
>>I damaged the front of my lens when the lens cover fell off. There is a
>>small bruise on the front coating. Any recommendations for a scene to
>>photograph to determine whether this will be significant? Would shooting a
>>plain white surface be best?
>
>To test for flare, I'd suggest shooting (with slide film) a dark wall
>with a bright light hitting the lens. Missing coating should not affect
>sharpness. However, if the glass is scratched, then sharpness might be
>affected and could be tested by shooting a detailed subject (such as a
>newspaper).
David Littlewood
London
Energy Consultant and Photographer
Newsgroups: rec.photo.equipment.35mm
Date: Mon, 10 Jul 2000
Subject: Leica Lens Aberrations -- True or False?
From: Brian Walsh m_che@dcn.davis.ca.us
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Leica Lens Aberrations -- True or False?
To respond directly, please remove the underscore from the address.
> On Mon, 10 Jul 2000 18:40:12 GMT, carbon_dragon@yahoo.com wrote:
>
> >"...it remains Leitz policy not to design lenses
> >purely to achieve high resolution of flat two dimensional
> >test charts, but deliberately to leave intact a modest
> >degree of aberration and curvature of field to improve the
> >rendition of three dimensional subjects." Collecting and
> >Using Classic Cameras, Ivor Matanle, Thames and Hudson
> >1986.
Newsgroups: rec.photo.equipment.large-format
Date: 22 Jul 2000
Subject: Re: Cemented lenses coming appart
PO Box 86
Spring Valley, WI 54767
Roy
Newsgroups: rec.photo.equipment.large-format
Date: Sat, 22 Jul 2000
Subject: Re: Cemented lenses coming appart
> I am the unfortunate owner of a Schneider Angulon 120mm.
> The rear element shows Newton rings as an indication of cemented
> glasses comming appart. The practical result is a very distorted plane
> of focus. The lens is practically unusable. My repairman says he cant
> do anything about it. Does anyone in the group have any suggestions ?
> I have been toying with the thought of placing the element in kind of
> springloaded jig, pressing it together, and heating it in an oven to
> reset the cement, but I have no idea to what degree this cement
> (Called Canadabalsam here) is subjectable to such treatment.
>
> John M. E. Dancke
> dancke@online.no
Newsgroups: rec.photo.equipment.large-format
Date: Sat, 22 Jul 2000
Subject: Re: Cemented lenses coming appart
focalpt@ecentral.com
The Focal Point
John Van Stelten
1017 South Boulder Road
Suite E-1
Louisville, CO 80027-0027
Tel.- 303-665-6640
Fax - 303-665-3803
http://www.411web.com/F/FOCALPOINT/
Steve Grimes
http://www.skgrimes.com
e-mail and other information are on the web site.
Summers Optical
http://www.emsdiasum.com
---
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Date: Tue, 22 Aug 2000
From: "Erwin Puts" imxputs@knoware.nl
Subject: [Leica] Internal focusing
From: bluffel@gr.hp.com (Bob Luffel)
Newsgroups: sci.astro.amateur
Subject: Re: Nikon's take on Flourite vs. ED glass
From: "Wayne D" wdewitt@snip.net
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Cleaning Marks?
Date: Sun, 03 Dec 2000
From: Russ & Kathy Thornton radarguy@gdi.net
Subject: Re: hasselblad V1 #1067
From: "Peter Klosky" Peter.Klosky@trw.com
To: hasselblad@kelvin.net
Subject: Rear Element Chips
Date: Sat, 02 Dec 2000
From: Peter Klosky Peter.Klosky@trw.com
Subject: Rear Element Chips
From Leica Topica Mailing List:
Date: Thu, 23 Nov 2000
From: Jim Brick jim@brick.org
Subject: Re: part 2, reply
Date: Mon, 4 Dec 2000
From: "Williams, Bill" BJWilliams@city.surrey.bc.ca
Subject: RE: Rear Element Chips
Date: Tue, 5 Dec 2000
From: Robert Welch robertwelch@earthlink.net
Subject: Bought the 60mm lens with chips
Date: Wed, 6 Dec 2000
From: Hugh Thompson painfree@istar.ca
Subject: Chipped rear element + candleblack?
Date: 4 Dec 2000
From: Patrick Bartek bartek@pdai.com
Subject: Re: Examining 60mm lens
Patrick Bartek
NoLife Polymath Group
bartek@pdai.com
Newsgroups: rec.photo.equipment.large-format
Date: 10 Dec 2000
Subject: Re: How to evaluate lens sharpness
Date: Wed, 20 Dec 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] OT: strange colour in a Jena Pancolar
>> Some glass "stains" or turns brown. Good optical glass should not do
>this
>> unless subjected to intense radiation. A few lenses were made with radio
>> active glass during WW-2 and often the radio-active elements have browned
>> with age.
>Hi all.
>I have a Jena Pancolar 50/1.8 which is... yellow! I don't mean a light
>yellow fog, but really yellow lenses!
>It is absolutely fine for BW, but unusable with colour film.
>Does this yellow colour mean it has been made form radio-active glass?
>Should I be worried?
>Ciao
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 27 Dec 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Off topic: Rapid Rectilinear
>Nobody mentioned the "trick" for using the older viewcameras
>lenses. And by the way, you can put them on a Rollei SL66
>by mounting one in a lens blank. Anyway the trick the
>oldtimers used to make the old lenses perform better, for
>black and white, of course, is to use a yellow filter in
>front of the lens. Somebody please explain how this works...
>Ed
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: "Q.G. de Bakker" qnu@worldonline.nl
Newsgroups: rec.photo.equipment.misc
Subject: Re: What is APO?
> I remember that in a german photomag test, a Leitz "standard" tele lens
> had better colour correction performance than some others marked "apo".
> It is not possible to correct colour dispersion perfectly, and there is
> no standard saying to which extend it must be corrected to call a
> lens "apochromatic".
> Since no manufacturer wants to waste apochromatic correction on a
> mediocre lens, apo lenses in general have better overall performance
> than others.
From Hasselblad Mailing List:
Date: Fri, 12 Jan 2001
From: Marc James Small msmall@roanoke.infi.net
Reply to: hasselblad@kelvin.net
Subject: New Zeiss Fungus Treatment
_________________________________
500ml bottle, INR 0117.361
1000ml bottle, INR 0117.360
From: Alan Davenport w7apd@home.com
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Specks of Dust inside Lens.
> I've recently sold my 28-105 lens on eBay, and the buyer complains
> that there are specks of dust inside the lens.
>
> I had never noticed this, and I'm very surprised, as I had taken good
> care of this lens. Moreover, my pictures were perfect, in my opinion.
>
> Should he worry about this, or is it normal in an 8 year old lens?
>
> Thanks
>
> Pierre
From Hasselblad Mailing List;
Date: Thu, 11 Jan 2001
From: "Q.G. de Bakker" qnu@worldonline.nl
Subject: Re: anyone ever repaired a chipped lens rear element?
> I purchased a SWC for a bargain price. It was a bargain because it has a
> pinhead nick on the rear element. [...]
From Rollei Mailing List:
Date: Tue, 23 Jan 2001
From: Edward Meyers aghalide@panix.com
Subject: RE: [Rollei] What is it with the 25mm Focal length
Date: Wed, 20 Dec 2000
From: "Mark Vints" mark.vints@skynet.be
Subject: Re: [NIKON] Contrast in a lens
Date: Thu, 21 Dec 2000
From: "John Owlett" owl@postmaster.co.uk
Subject: [NIKON] Re: Contrast in a lens
> What exactly is "contrast" when referred to in respect of a lens? In
> case of a film the word "contrast" perhaps relates to its ability to
> render different colour shades accurately without any merging of the
> colours. The same may be true in case of B&W where the shade and the
> highlight are clearly distinuished at the borderline. Or am I wrong in
> this? But a lens, after all, is a piece of glass. It passes through the
> light at different intensities. depending on the subject, to form the
> right image at the film plane. So if each of these light elements is
> accurately transferred to form the right image would it not mean that
> the lens is "sharp"? What exactly is the difference between sharpness
> and contrast?
John Owlett, Southampton, UK
Date: Wed, 20 Dec 2000
From: "Ed Alban" edalban@attcanada.net
Subject: Re: [NIKON] Contrast in a lens
> What exactly is the difference between sharpness and contrast?
Vancouver Canada
Date: Sun, 24 Dec 2000
From: Eric Goldstein egoldstein@usa.net
Subject: [Rollei] Re: Newbie - help me select an old Rolleiflex or
Rolliecord TLR
> Now, as for three-element lenses (or even
> doublets, for that matter), I have found that lots of
> folks seem to forget that those old, beautiful images
> made pre-1900 were made with lenses that were not only
> uncoated, but likely loaded with "cleaning marks" as
> well as being of two- or three-element construction.
Date: Mon, 08 Jan 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] The Truth About the Sixth Element ...
>Richard (Knoppow that is),
>could you please elaborate a bit on color-correction of lenses, and color
>-correction when taking pics (like with dekamired filters)?
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Mon, 11 Dec 2000
From: Gary Todoroff datamaster@humboldt1.com
Subject: Re: 100/3.5 vs 120/4 at close-focus
Gary Todoroff
Eureka, CA
Date: Tue, 20 Mar 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re:(OT) Xenon ?
>I have an early-1950s Karomat with the f/2 Xenon, and I was frankly
>a bit disappointed with the lens -- not as sharp as I expected. The
>coating is somewhat scratched up, though, so that may the source
>of my disappointment.
>--
>Curtis Croulet
>Temecula, California
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Thu, 22 Mar 2001
From: David Lew dlew2@yummysushi.com
Subject: Re: [NIKON] dust in Nikkor lenses
Date: Wed, 21 Mar 2001
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Rollei/Zoom/Telephoto
> From: "John Kufrovich" jkufrovich@ev1.net
> Date: Wed, 21 Mar 2001
> Subject: Re: [Rollei] Rollei/Zoom/Telephoto
>
> Interesting, lenses that I have dealt with, use spacers to seperate elements
> or groups. There is some play between the actual lens and the barrel. The
> only elements that I could see effected by thermal expansion are the front and
> rear. Perhaps I need to look carefully at a cut away view of a lens.
> This brings up an interesting question. Does Rollei paint or darken the edges
> of individual elements inside a lens.
From Minolta Mailing List:
Date: Thu, 22 Mar 2001
From: "Kent Gittings" kent@ism.com
Subject: RE: vivitar series I 90-180 flat-field lens
Date: Wed, 21 Mar 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re:(OT) Xenon ?
>Richard Knoppow at dickburk@ix.netcom.com wrote:
>
>> you wrote:
>>> I have an early-1950s Karomat with the f/2 Xenon, and I was frankly
>>> a bit disappointed with the lens -- not as sharp as I expected. The
>>> coating is somewhat scratched up, though, so that may the source
>>> of my disappointment.
>>> --
>>> Curtis Croulet
>>> Temecula, California
>>>
>> Also shine a flashlight through it and check the condition of the cement
>> in the cemented elements. Some lenses of this period were cemented with
>> synthetic cement which becomes turbid with time. That louses up contrast
>> and can make the lens look soft.
>> This is a different sort of failure from what you find with Canada
>> Balsam, where usualy the cement just starts to oxidize and crystalize at
>> the edges. The "warm" quality of some Xenons may come from cement which has
>> started to oxidize and discolor a little.
>> ----
>> Richard Knoppow
>> Los Angeles,Ca.
>> dickburk@ix.netcom.com
>
>Hmmm. Maybe that's what's with my Karomat and IIa Xenons. Is it sort of an
>uneven milky look?
>
>pk
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From Rollei Mailing List:
Date: Wed, 21 Mar 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Rollei/Zoom/Telephoto
>Interesting, lenses that I have dealt with, use spacers to seperate
>elements or groups. There is some play between the actual lens and the
>barrel. The only elements that I could see effected by thermal expansion
>are the front and rear. Perhaps I need to look carefully at a cut away
>view of a lens.
>
>This brings up an interesting question. Does Rollei paint or darken the
>edges of individual elements inside a lens.
>
>John Kufrovich
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Fri, 23 Mar 2001
From: Richard Urmonas rurmonas@senet.com.au
Subject: Re: [Rollei] Newbie.What to look for to exclude coating
separation
> I'm considering a 2.8 E (with meter) with Planar and
> wish to know
> 1.)what to look for to make sure there is no
> lens coating separation?
> 2.) Is there any difference between coating of Planar
> on E when compared with the later F model?
> 3.)Contact number of Mr.Maxwell and is it possible to
> change the screen yourself on 2.8E as i'm at
> Downunder.
rurmonas@senet.com.au
Date: Tue, 24 Apr 2001
From: Bob Shell bob@bobshell.com
Subject: Re: [CONTAX] First shots with RTS III...what a joy !
> From: Joe Doehler contax@doehlerUSA.com
> Date: Tue, 24 Apr 2001
> Subject: Re: [CONTAX] First shots with RTS III...what a joy !
>
> I would not buy a lens with a bubble. You are right in stating that a
> bubble *by itself* is little more than a cosmetic flaw. However, much of
> the know-how in making modern glass revolves around making it homogeneous.
> A bubble indicates to me that something went out-of-spec in the
> manufacturing that affected the homogeneity of the batch near that bubble,
> and that you are likely to deal with a piece of glass that is not as good
> as it was meant to be.
Newsgroups: rec.photo.equipment.large-format
Date: Sat, 07 Apr 2001
Subject: Re: 152mm Ektar
>I have a 152mm/4.5 Kodak Ektar in a Graphic Supermatic shutter.
>
>It has a bi-post for a flash. Can I use this with my modern Vivitar 285?
>Should I use a shutter speed of 1/50th?
>
>The lens has a blueish tint to it, but looking closely at it the front cell
>has various cleaning marks and the glass actually has small bubbles in it!
>
>should I dump this lens and go back to my 135mm/4.7 in Graflex shutter?
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Date: Wed, 11 Apr 2001
From: Eric Goldstein egoldstein@usa.net
Subject: Re: [Rollei] Re: New lenses on old Rolleiflex?
> Can you count reflections in a cemented pair?
Date: Wed, 11 Apr 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re: New lenses on old Rolleiflex?
>Richard
>
>The Ektar we used was FIVE elements in three
>groups. It had two cemented pairs. I saw the
>lens when it was disassembled, before installing
>in the 2.8A.
>
>Can you count reflections in a cemented pair?
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Tue, 8 May 2001
From: "Cousineau , Bernard" bcousineau@tmisolutions.com
Subject: RE: [CONTAX] Focus shift with filters...
> From: Austin Franklin
> What is the optical truth about focus shift with filters? If I have a
> perfectly coplanar filter (both surfaces parallel), in front
> of the lense,
> and it is perpendicular to the axis of the lense, is there
> ANY focus shift
> at all?
Date: Mon, 28 May 2001
From: Johnny Deadman john@pinkheadedbug.com
Subject: Re: [Leica] Re: Cleaning Marks/ Recoating
> I've new heard so many differing opinions regarding cleaning marks; I wonder
> if anyone has done a more scientific examination of this question. One site
> on the Web claims that multiple cleaning marks are relatively serious, in
> the hierarchy of lens flaws. Harry Fleenor (one of the world's great Rollei
> repairmen) says that at most light marks will cause a very minor lowering of
> contrast.
John Brownlow
http://www.pinkheadedbug.com
Date: Mon, 28 May 2001
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Leica] Re: Cleaning Marks/ Recoating
>Ken Ruth (another
>legendary repairman) told me that it's impossible to grind and recoat a lens
>without doing damage.
Date: Mon, 16 Apr 2001
From: David Lew dlew2@yummysushi.com
Subject: Re: [NIKON] scratch in lens
> Personally, I will not accept lenses with scratch inside, no matter it
affect picture quality or not. In Malaysia (and I assume Singapore same
too), the puchase policy is a bit different, one can't buy and then return
the goods for refund even if the goods (lens, camera...etc.) has defect in
it. Some shops will give 3 days for one to one exchange, but very seldom
and rare they will refund the money. In most case, one have to EAT what
he/she has spent. So, the best way is to check very carefully when buying.
>
> For checking dust/scratch in lens, I find yellow light gives better
viewing. Try point the lens at a yellow light lamp, and not white lamp. I
find checking at outdoors with bright sunlight is kind of hard too...the
too bright light makes me hard to see the tiny dust...or scratch inside
the lens.
>
>
> Just my experience to share...
>
> Regards,
> Kho King, Koh
>
> ps: I agree totally with someone saying: Who wants to buy a SCRATCHED
> MECEDES although it can still function perfectly?
From: dickburk@ix.netcom.com (Richard Knoppow)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Let me konw "Cleaning marks" in lens
>Photographter wrote:
>>
>> Hi
>> I am very interested in photography
>> A few days ago, I heard any word "cleaning mark"
>> I'd like to know the means.
>
>
>Cleaning marks are very fine scratches or other abrasions in the surface
>of a lens, caused by overly-agressive cleaning methods, typically with a
>cloth containing sand, grit or other debris. Cleaning marks reduce the
>resale value of a lens, but, when minor, have little optical significance.
>
>James Meckley
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
Newsgroups: rec.photo.equipment.large-format
Date: 07 Jun 2001
Subject: Re: Let me konw "Cleaning marks" in lens
Ted Harris
Resource Strategy
Henniker, New Hampshire
From: jbh@magicnet.net (John Hicks)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Let me konw "Cleaning marks" in lens
>Hi
> I am very interested in photography
>A few days ago, I heard any word "cleaning mark"
John Hicks
Date: Sat, 30 Jun 2001
From: "Mike" NEDSNAKE@email.msn.com
Subject: Re: Mamiya TLR Lens Defect?
www.mfcrepair.com
> Hi,
>
> I've owned a Mamiyq C33 with an 80mm lens (gold lens coating) for 10
> years. When I'm not using it, I keep it stored in a cool, dry place in
> a camera bag. Every couple of years I've noticed what appeared to be
> flecks of the gold lens coating inside the elements of the taking lens.
> I've had the lens cleaned twice and each time the repair person
> (different each time) that the problem wouldn't occur again. Now I see
> what appears to be a hair that has found its way into the lens. Is this
> typical for this lens? Should I just chuck it and get another one? Is it
> possible to fix this problem?
>
> Thanks for your help.
>
> Mark
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Scratches on lenses (effect and repair)
Date: Thu, 26 Jul 2001
>How much effect will a single deep glass scratch, say with a length 10%
>of the radius, have on the performance of a lens? I presume the main
>problem is light scattering leading to flare.
>
>How about if you fill the scratch with opaque? Will that effectively
>remove most of the problem?
>
>--
>Mark Anderson
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: slberfuchs@aol.com (Ted Harris)
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Scratches on lenses (effect and repair)
Resource Strategy
Henniker, New Hampshire
[update: Paul van Walree info@vanWalree.com http://www.vanWalree.com/]
Newsgroups: rec.photo.equipment.35mm
Subject: flare and distortion pages
Date: Mon, 03 Sep 2001
and got useful feedback. Now I have pages up regarding:
flare: http://www.xs4all.nl/~odobenus/fi.html
distortion: http://www.xs4all.nl/~odobenus/di.html
Regards,
W.
Date: Mon, 5 Nov 2001
From: "Joe B." joe-b@clara.co.uk>
Subject: [Rollei] "Balsam" issues with some Zeiss lenses?
To: rollei@mejac.palo-alto.ca.us
A repairman I spoke to tonight said he's seeing a lot of Zeiss lenses from the
60's with what people call balsam problems- he says it is actually optical
cement and not balsam that is giving this problem with these lenses. I was
originally asking about a 120 S-Planar for the SL66 that had a "balsam problem"
that was going cheap, but he persuaded me that this might not be so easy to
recement and so I have given up on that idea. The Zeiss lenses for the SL66 are
from this period and I wonder how much of a problem this is, or is going to be.
And I also wonder if the Rollei-manufactured SL66 lenses are likely to have this
problem- maybe they were made differently. I'd really like more information
because I don't want to buy lenses that have the potential for decementing
without there being any good fix for the problem. Any additional info would be
welcomed.
Joe B.
Date: Mon, 05 Nov 2001
To: rollei@mejac.palo-alto.ca.us
From: Marc James Small msmall@roanoke.infi.net>
Subject: [Rollei] Separation Issues and Zeiss Lenses
Joe B. wrote:
>A repairman I spoke to tonight said he's seeing a lot of Zeiss lenses from the
>60's with what people call balsam problems- he says it is actually optical
>cement and not balsam that is giving this problem with these lenses. I was
>originally asking about a 120 S-Planar for the SL66 that had a "balsam problem"
>that was going cheap, but he persuaded me that this might not be so easy to
>recement and so I have given up on that idea. The Zeiss lenses for the SL66 are
>from this period and I wonder how much of a problem this is, or is going to be.
>And I also wonder if the Rollei-manufactured SL66 lenses are likely to have this
>problem- maybe they were made differently. I'd really like more information
>because I don't want to buy lenses that have the potential for decementing
>without there being any good fix for the problem. Any additional info would be
>welcomed.
The problem DOES occur and, yes, it does not involve "Balsam" as Zeiss quit
using Balsam as a cement for lens elements donkey's years back.
The problem only afflicts selected lenses, and I don't recall that the
5.6/120 S-Planar was one such. The most heavily affected are the 35mm,
85mm, and 115mm Pro-Tessars for the Zeiss Ikon Contaflex III through S line
and the Rolleiflex TLR prism -- and, in these cases, the poor cement used
seems to have only been in use for a very brief window of time, possibly
from 1960 to 1963. I have never heard of a Rollei-made Zeiss lens
suffering from the problem.
Marc
msmall@roanoke.infi.net
Date: Mon, 05 Nov 2001
Subject: Re: [Rollei] Separation Issues and Zeiss Lenses
From: Bob Shell bob@bobshell.com>
To: rollei@mejac.palo-alto.ca.us>
> From: Marc James Small msmall@roanoke.infi.net>
> Date: Mon, 05 Nov 2001
> To: rollei@mejac.palo-alto.ca.us
> Subject: [Rollei] Separation Issues and Zeiss Lenses
>
> The problem only afflicts selected lenses, and I don't recall that the
> 5.6/120 S-Planar was one such. The most heavily affected are the 35mm,
> 85mm, and 115mm Pro-Tessars for the Zeiss Ikon Contaflex III through S line
> and the Rolleiflex TLR prism -- and, in these cases, the poor cement used
> seems to have only been in use for a very brief window of time, possibly
> from 1960 to 1963. I have never heard of a Rollei-made Zeiss lens
> suffering from the problem.
I had a 120 S-Planar for SL66 bought around 1973 as I recall. It had
belonged to a doctor before me. It had serious separation when I got it
and I sent it out for recementing. I later got rid of it because it was
simply too sharp for glamour photography.
The lens I saw most often in need of recementing was the 150mm Sonnar for
Hasselblad, 60s vintage. Like Marc I never saw a Rollei-built lens with
separation.
Bob
From: Rollei@davidmorton.org
To: rollei@mejac.palo-alto.ca.us
Subject: RE: [Rollei] "Balsam" issues with some Zeiss lenses?
Date: Tue, 6 Nov 2001
Joe B. wrote:
"A repairman I spoke to tonight said he's seeing a lot of Zeiss lenses from
the
60's with what people call balsam problems- he says it is actually optical
cement and not balsam that is giving this problem with these lenses."
I've heard this too, from a specialist Rollei repairer in London. The lens
we were discussing was the 135mm f4 Sonnar in the Tele-Rollei, and he warned
me to check *very* carefully for this effect. His optical specialist has had
the cemented elements of two Tele taking lenses sitting in a bath of
whatever-it-is-they-use-to-take-them-apart for over *twelve months* and they
won't separate (so they can't recement them).
www.ffordes.co.uk has three Tele Rolleis for sale on its site, and when I
enquired about the lens condition by mail a few weeks ago I was told that
two of them had separation problems in the taking lens.
--
David Morton
dmorton@journalist.co.uk
Date: Tue, 06 Nov 2001
To: rollei@mejac.palo-alto.ca.us
From: Richard Knoppow dickburk@ix.netcom.com>
Subject: RE: [Rollei] "Balsam" issues with some Zeiss lenses?
you wrote:
>Joe B. wrote:
>
>"A repairman I spoke to tonight said he's seeing a lot of Zeiss lenses from
>the
>60's with what people call balsam problems- he says it is actually optical
>cement and not balsam that is giving this problem with these lenses."
>
>I've heard this too, from a specialist Rollei repairer in London. The lens
>we were discussing was the 135mm f4 Sonnar in the Tele-Rollei, and he warned
>me to check *very* carefully for this effect. His optical specialist has had
>the cemented elements of two Tele taking lenses sitting in a bath of
>whatever-it-is-they-use-to-take-them-apart for over *twelve months* and they
>won't separate (so they can't recement them).
>
>www.ffordes.co.uk has three Tele Rolleis for sale on its site, and when I
>enquired about the lens condition by mail a few weeks ago I was told that
>two of them had separation problems in the taking lens.
>
>--
>David Morton
>dmorton@journalist.co.uk
>
FWIW, A company called Summers Optical makes optical cements and
solvents. Their web address is:
http://www.emsdiasum.com/Summers/optical/cements/default.html
Even if you
are not interested in taking on recementing yourself the primer here makes
interesting reading.
Synthetic cements have been used for nearly all lenses from the late
1940's. A few manufacturers began using them even earlier especially for
aerial lenses for use at high altitude. These lenses are subjected to
temperatures which will almost instantly crystalize Canada Balsam, making
the layer cloudy and the lens useless.
Many kinds of cements have been used. The early ones were mostly
thermosetting. While synthetic cements should have a much longer lifetime
than Canada Balsam there are subject to some problems in assembly and
curing. I've seen some lenses, including Zeiss lenses for the Contarex,
which had what looked like large bubbles in them. This is the cement
separating. I have also seen a few Kodak lenses where the cement layer has
become turbid, looking like wax paper.
Many lenses can be recemented. If the elements are not completely
separated the technique is to bathe the lens in a hot solvent solution. The
solvent Summers sells operates at around 340F. The problem is that
sometimes the thermal shock can cause the elements to fracture. The
Summer's solvent is started cold to avoid this problem. Once separated the
lenses can be cleaned with Acetone and pure Ethyl alcohol and recemented.
Summers sells both binary type and UV setting cements. I've used the
conventional binary type. This requires curing at 130F for an hour. There
is also a room temperature curing cement but I prefer to have the longer
working life of the mixed cement. The temperature is not critical and the
recementing procedure is not too hard to do.
Most cemented elements have edges which are carefully centered. When
these are clamped together the entire assembly will be centered correctly.
The difficulty comes with lenses with different diameter elements, such as
the Schneider Angulon. I've not recemented a finder prism but would guess
that its practical to do.
Steve Grimes also has a little on lens re-cementing on his web site
http://www.skgrimes.com
He uses prisms to clamp the lens edges. I've found that even large
machine nuts seem to be suitabley square. A sheet of thick glass is used as
the reference surface. I've used an ordinary gas oven for curing although a
temperature controlled electric oven would be ideal.
I have also recemented using Canada Balsam, but it is actually more
difficult and fussy to use and the results are not as good.
Lenses cemented with Canada Balsam can be gotten appart by gentle
heating. The text books say to use a frying pan but I've also had good luck
placing the elements in water and heating it until the fall apart.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
Date: Thu, 08 Nov 2001
To: rollei@mejac.palo-alto.ca.us
From: Richard Knoppow dickburk@ix.netcom.com>
Subject: Re: [Rollei] Separation Issues and Zeiss Lenses
you wrote:
> bob@bobshell.com (Bob Shell) wrote:
>
>> > The problem only afflicts selected lenses, and I don't recall that the
>> > 5.6/120 S-Planar was one such. The most heavily affected are the 35mm,
>> > 85mm, and 115mm Pro-Tessars for the Zeiss Ikon Contaflex III through S line
>> > and the Rolleiflex TLR prism -- and, in these cases, the poor cement used
>> > seems to have only been in use for a very brief window of time, possibly
>> > from 1960 to 1963. I have never heard of a Rollei-made Zeiss lens
>> > suffering from the problem.
>>
>>
>> I had a 120 S-Planar for SL66 bought around 1973 as I recall. It had
>> belonged to a doctor before me. It had serious separation when I got it
>> and I sent it out for recementing. I later got rid of it because it was
>> simply too sharp for glamour photography.
>>
>> The lens I saw most often in need of recementing was the 150mm Sonnar for
>> Hasselblad, 60s vintage. Like Marc I never saw a Rollei-built lens with
>> separation.
>>
>> Bob
>
>I'm now viewing my 150mm Zeiss Sonnar for SL66 with some concern. I wonder if
>there is any way of knowing whether this lens is likely to separate at some
>future time or not. And I wonder if I can assume it is effectively the
same lens
>as the Hasselblad lens- same optics, same manufacturer. It looks fine at the
>moment, but if I wait until I see some evidence of separation, I will have
left
>it too long. I have half a mind to sell it forthwith. Have you (or anyone
else)
>ever heard of the SL66 150 Zeiss Sonnar developing this problem?
>
>Joe B.
>
My guess is that if the lens shows no sign of separation its not going to
separate. Unlike Canada Balsam, which slowly crystalizes at the edges,
properly cured synthetic cements should have virtually indefinite lifetime.
I suspect the bad Zeiss lenses are due to either defective cement or some
problem in curing it. The problem may not have been recognized at the time.
Likely it affects lenses made only over a fairly short time.
The separated Zeiss lenses I've seen (from a Contarex) looked like they
had large bubbles in them. However, I've also seen other manifestations of
bad synthetic cements on other lenses. Some Kodak lenses get an overall
haze in the cement which under magnification looks slightly wrinkled, like
reticulated film. The main effect of this is to diffuse the image a little,
unless its very bad.
Separating cement can also give a sort of oil-slick effect, probably from
Newton's rings from the variation of index in the bad cement.
The difficulty of recementing depends on the construction of the lens and
the difficulty of getting the components apart. Old lenses, cemented with
Canada Balsam are not difficult at all to get apart, nor are lenses with
synthetic cement which has sufficiently separated. However, where synthetic
cement is just starting to have trouble the lens must be treatet in hot
solvent, with the consequent risk of thermal shock.
There are a couple of people in the US who offer recementing services.
One is Steve Grimes the other is John van Stelten. I know Steve a little,
he is a carful workman. I've not had direct experience with van Stelten but
he has a good reputation.
Recementing is expensive because there is a lot of hand work. Whether its
justifiable or not obviously depends on the lens.
Its not too difficult to do your own recementing but I would suggest
giving any really valuable lens to someone who does it all the time.
In a previous post I gave the URL of Summers Optical, who supplies both
optical cements and accessory items. They have a pretty good on-line primer
on cementing. I wish it were available as a PDF (maybe it is now, I haven't
looked lately).
Unfortunately, the cements and the solvents must be shipped as hazardous
materials. The haz mat charge nearly doubles the price. I strongly suggest
ordering cement and solvent at the same time since I think the haz mat
charge is per shipment rather than by item.
Recementing simple lenses, like Tessars, is easy. The main problem with
small Tessar type lenses is that the rear (cemented) element is likely to
be mounted in a "burnished" or "spun-in" mount which requires some
machining to get apart. The mechanical work is much more difficult than the
recementing.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From: Stephe Thayer ms_stephe@excite.com>
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: air bubbles in the lens
Date: Thu, 15 Nov 2001
Andrew wrote:
> I found in my Super Ikonta 645 some small air bubbles ( out of center ) in
> the front glass while cleaning it.
> This is Carl Zeiss Jena nr.1675580 lens. In what years it was made? Why so
> low quality Zeiss produced? Do this degradate image quality?
>
Won't affect it at all. While not real comon in zeiss lenses, there were
plenty of lenses from that time that had bubbles in the glass. I have about
ten old folders and 2 of them have a small bubble somewhere in the glass.
Something about quality glass at that time being hard to make with no
bubbles and they found it didn't hurt anything anyway.
--
Stephe
From: "Roland" roland.rashleigh-berry@virgin.net>
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: air bubbles in the lens
Date: Thu, 15 Nov 2001
Andrew andrew_jakk@hotmail.com> wrote
> I found in my Super Ikonta 645 some small air bubbles ( out of center ) in
> the front glass while cleaning it.
> This is Carl Zeiss Jena nr.1675580 lens. In what years it was made? Why so
> low quality Zeiss produced? Do this degradate image quality?
This is not a result of low quality. These are balsam bubbles and are quite
common with lenses that are quite old. It will not affect picture quality.
From: elemar@home.com
Subject: Re: air bubbles in the lens
Newsgroups: rec.photo.equipment.medium-format
Date: Thu, 15 Nov 2001
>From what I have read, these bubbles were a result of the difficulties
associated with using 'rare earths' (those elements on the bottom of a
periodic table) in optical glass. The glass had to be manufactured at higher
temperatures which resulted in bubbles from the mixing container.
Other glass types did not require this high of a temperature, so there were
no bubbles in it.
So, at that time, small bubbles were an indication of better glass.
Times have changed and manufacturing techniques have gotten better, so you
don't see many bubbles.
Ray
James W.\(Jim\) Simmons jwsimmons@abs.adelphia.net> wrote:
: At one time long ago, the 40 ~ early 60's, air bubbles were considered a
: sign of very good glass and was often found in the better lenses.
: Jim
: "Andrew" andrew_jakk@hotmail.com> wrote
:> I found in my Super Ikonta 645 some small air bubbles ( out of center ) in
:> the front glass while cleaning it.
:> This is Carl Zeiss Jena nr.1675580 lens. In what years it was made? Why so
:> low quality Zeiss produced? Do this degradate image quality?
:>
:> Thanks,
:> Andrew
--
E. Ray Lemar elemar@home.com
From: slberfuchs@aol.com (Ted Harris)
Newsgroups: rec.photo.equipment.large-format
Date: 15 Nov 2001
Subject: Re: Cleaning marks
Don .. The simpletst answer to your question is it depends ... you knew I was
gonna say that! If you are buying from a reputable dealer then they will let
you try the lens out. KEH and midwest both do this for example. Npow for more
qualifications on the "it depends" ....:
1) it depends on where the cleaningmarks are, if they are pretty much out to
the edges and have little impact when the lens is stopped down they may make no
difference at all IF they are on the front element, more problems onthe rear
element.
2) it depends on what sort of light you are shooting in,if you shoot largely in
situations where flare is not likely to become an issue then they have less
relevence.
3) it depends on what film you are using ... more problems with color than with
B&W; since B&W; will suffer in terms of reduced contrast and color that + lower
saturation.
4) it depends on how picky you are and how far you want to pursue image
clarity.
Having said allt hat you can still make passable images with lenses that are
heavily marked but if you cna afford to avoid same you should do so. For the
most part a lens that has heavily visable cleaningmarks when you hold it up to
a direct light will have reduced contrast and reduced sharpness and should not
be very expensive. But they can make decent and in some situations very
pleasant images. If you or anyoneelse is intersted I will scan a negative I
jsut came across that was made with a battered old warhorse of a wollensack 135
something or other that was so fullof cleaning marks it was almost opaque.
OTOH I have a 90 mm Grandagon that has an ugly smudge on the coating of the
rear element and it has had no impact at all on image quality. Kerry Thalmann
had a 150 mm Super Symmar HM that had a mottled coating onthe rear lelemnt that
had absolutely no impact on image quality. Finally, i have been testing a 75
mm Fujinon SWD tht has a very few tiny pinpricks scattered on the front element
... it is a dog ... arf arf dog. I have not been able to get a critically
focused image with it and am totally surprised. A long way of saying you gotta
try it out. If you can't try it out don't buy it if it aint perfect.
Cheers,
Ted
Ted Harris
Resource Strategy
Henniker, New Hampshire
From: Stephe Thayer ms_stephe@excite.com>
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Cleaning marks
Date: Thu, 15 Nov 2001
Don Wallace wrote:
> Just how bad do the cleaning marks on a lens have to be before the image
> quality
> is degraded? I have seen some classic lenses at very low prices because of
> what were described as "bad cleaning marks". These were also reputable
> dealers.
>
My experience has been they are more flare prone and theoretically should
have less contrast.. I have a minoltacord that if you look through the lens
from behind into a light, the front element looks like an ice skating rink.
When I saw this I almost took it straight back to the shop I got it at. I
went out instead and shot a roll of film and it was wonderful. I have
another minoltacord that has perfect glass and in print, I can't see any
difference whatsoever. I don't shoot into direct light and always use a
lens hood or shade the lens, which is a good idea with any lens. My advice
if you can buy it from somewhere that will let you return it if it's a dog
is to go ahead and try it, you might be surprised. Also as you probably
already realise, it won't be worth much when you go to sell it either..
--
Stephe
From: hkrafft@polbox.com (Hartmut Krafft)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: air bubbles in the lens
Date: 16 Nov 2001
andrew_jakk@hotmail.com (Andrew) wrote:
> I found in my Super Ikonta 645 some small air bubbles ( out of center ) in
> the front glass while cleaning it.
> This is Carl Zeiss Jena nr.1675580 lens. In what years it was made? Why so
> low quality Zeiss produced? Do this degradate image quality?
FWIW, from the preface of my Krasnogorsk-made MC Zenitar-M
2.8/16mm Fisheye for 35mm (M42, also available in most other
manual focus mounts) cameras (BTW: a really stunning and
absolutely excellent lens both optically and mechanically!):
\begin{quotation}
If you encounter bubbles or inclusions in the elements of the
lens, don't let this trouble you: they will not in any way
degradate the high optical quality of the lens.
\end{quotation}
Mine has no such inclusions, though...
Hartmut
--
Date: Sat, 12 Jan 2002
From: Lewis Weber imagesci@worldnet.att.net>
To: hasselblad@kelvin.net
Subject: [HUG] 150 Sonnar with scratch
Hello HUG:
I was recently traded some exercise equipment for a 150 Prontar f/4 CF
Sonnar lens that has a small scratch (less than one millimeter) in the
center of the rear element. The scratch actually goes into the glass a
bit. Otherwise the lens is mint. The scratch has yet to show up on my
chromes, but it bugs me to no end just knowing that the scratch is
there. Opinions on whether or not it is worth getting fixed?
Lewis Weber
Date: Sat, 12 Jan 2002
Subject: Re: [HUG] 150 Sonnar with scratch
From: Peter Rosenthal petroffski@mac.com>
To: hasselblad@kelvin.net>
> I like that idea. Can I use some carefully applied clear nailpolish to
> fill in the scratch? Will the solvent in the nailpolish do more harm
> than good?
>
> Lewis
Yo Lewis-
The main point of filling the scratch is to prevent light from passing
through the scratch and thereby (I sincerely apologize for using the word
thereby) preventing lots of light scatter. Well not lots, but some. You have
to use BLACK paint or crayon. Try to use the absolute minimum, just enough
to fill it. Any more than that and you risk making a shadow of it on the
film. Also...if it is too large a spot, diffraction around it's larger edge
will cause scattering of it's own. As hokey as it sounds, it's a cheap and
effective way of preventing excessive lowering of the MTF of your lens.
g'luck!!
Peter
--
Peter Rosenthal
PR Camera Repair
111 E. Aspen #1
Flagstaff, AZ 86001
928 779-5263
Date: Sun, 13 Jan 2002
To: rollei@mejac.palo-alto.ca.us
From: John Hicks jhicks31@bellsouth.net>
Subject: Re: [Rollei] Symmar 150/5,6
you wrote:
>A seller has a Schneider Symmar 150/5,6 in good shape for sale. It's from
>1967 according to the serial number.
>
>Is it a good lens? Is $80 the right price?
You may see white spots around the periphery of some of the lens
elements; this is actually a paint problem and isn't really of any concern
and most likely won't get worse for a long time, so if you see that don't
let it scare you off. Virtually all older Schneider lenses have it.
Check very carefully for separation. This appears as a silvery or
oil-slick spot or can be a shiny star. For the asking price, a very slight
amount at the edge would be acceptable. Of course check for fungus.
If the lens is in good shape and is in a working shutter, the price is a
steal.
John Hicks
jhicks31@bellsouth.net
From: "bradleya" bradleya@ms54.hinet.net>
To: hasselblad@kelvin.net>
Subject: [HUG] Re: Lewis and his scratched lens
Date: Sun, 13 Jan 2002
Lewis,
I'm sure that exercise equipment had a few scratches on it, so
scratch-wise you probably came out on the long end of the stick :-)
Seriously, I have a 50 FLE that was shipped to me with a filter attached
and the package took a good whack, shattering the filter. As a result,
the lens got a few microscopic gouges taken out of the glass and several
other little peck marks in the coating.
Of course I was devastated because although the lens was sold as used,
it was inflawless condition.
I have shot at least ten test rolls through this lens at all settings
and it is as sharp as Granny's whiskers.
=20
(Provia 100 =3D 20X Ilfochrome 8X8's)
Guess what, I know the blemishes are there, and if I ever would want
to sell it the buyer would immediately want $1000.00 off. Tough luck, I
didn't buy it to sell, I bought it to use.
Don't worry nor fret. Use it and enjoy it. I'm off to Nepal next
Sunday for four weeks (fourth trip), and the fifty will get a lot of
use.
Sleep well.
Brad Vance
From: "Sharookh Mehta" first@vsnl.com>
To: hasselblad@kelvin.net>
Subject: Re: [HUG] 150 Sonnar with scratch
Date: Sun, 13 Jan 2002
I had the same problem on a 140-280 which I used some time back. No trace of
it showed up on my pics. Almost impossible - wide open.
Sharookh
----- Original Message -----
From: "Lewis Weber" imagesci@worldnet.att.net>
To: hasselblad@kelvin.net>
Sent: Saturday, January 12, 2002 11:36 PM
Subject: [HUG] 150 Sonnar with scratch
> Hello HUG:
>
> I was recently traded some exercise equipment for a 150 Prontar f/4 CF
> Sonnar lens that has a small scratch (less than one millimeter) in the
> center of the rear element. The scratch actually goes into the glass a
> bit. Otherwise the lens is mint. The scratch has yet to show up on my
> chromes, but it bugs me to no end just knowing that the scratch is
> there. Opinions on whether or not it is worth getting fixed?
>
> Lewis Weber
Date: Sun, 13 Jan 2002
Subject: [HUG] Re: Lewis and his scratched lens
From: Peter Rosenthal petroffski@mac.com>
To: hasselblad@kelvin.net>
"Your 50 FLE isn't the first lens I've seen damaged by a broken filter. As a
matter of fact, the O-N-L-Y front elements I've ever seen damaged were
damaged by a broken filter. This reporting ups the count to five. Five by a
broken filter, zero with no filter."
Eeeeeee Gads!!!!
I can't let this go by without comment! While no doubt well
intentioned, this stuff borders on irresponsible. While the only damage Jim
has seen to front elements has been with filters on, I have to say my count
is very, very different and have come to different conclusions entirely. The
original post of this thread was damage to a rear element where obviously no
filter was installed on the rear element. He forgot to add this to his
total. While impact damage to lens glass does happen with filters on, to
imply that this is the only way (or even the most likely cause) is wrong.
Not to pull rank or anything, but I've seen thousands, maybe tens of
thousands of lenses with damage because of no filter. I'm not just talking
about impact damage to glass as has been described, but cleaning damage, and
no protection from impact.
Most people on earth figure cleaning is good. It would be hard to
dispute this on principle, but in reality a lens that has been cleaned
poorly or continuously, functions much worse than one that is just dirty.
If dust or sand is between you and the glass when you clean it, it WILL
scratch the coatings. Do this enough times (as is necessary when there is
no filter installed) and your coatings will suffer. A lens element with bad
coatings is no less damaged than one with scratches on the glass itself.
Ruined is ruined. There is no damage I see in my business more common than
scratched coatings. None. Except maybe dirty lens elements. Both can be
prevented almost completely by filters. Sure filters get scratched, but
it's cheaper than the alternative and is not permanent.
Along with scratched coatings I see many, many lenses that have been
saved by the use of filters. How about the guy who looks in his rearview
mirror while driving away from a shoot just in time to see his 150 CF
following him down the road like a loyal puppy. The rear lens cap protected
the rear element while the front filter protected the glass and filter
mount. It looked like hell but there was no damage to the glass. He was then
able to put on a new filter and use it. He was very happy. Or how about
the poor fellow who dropped his 50 C and it landed in the cinder sand that
we have in abundance here in N. Arizona. The filter looked like hell but he
removed it and kept shooting. And on and on and on....
My moral to this story is any protection is good protection (good
filters included) and should be used with a smile and confidence. Leaving
filters off to protect lenses is a bad idea. :=80}
Peter
--
Peter Rosenthal
PR Camera Repair
111 E. Aspen #1
Flagstaff, AZ 86001
928 779-5263
From: "Joseph Codispoti" joecodi@charter.net>
To: hasselblad@kelvin.net>
Subject: Re: [HUG] Re: Lewis and his scratched lens
Date: Mon, 14 Jan 2002
In response to Peter Rosenthal petroffski@mac.com>
Peter,
Regarding the filter-for-protection issue, there are two well entranched
camps resolutely diploying all arguments to support or negate the usefulness
of such a devise. I tend to agree with your reasoning that where the broken
filter may have damaged the lens, the cause of the broken filter might have
damaged the lens directly anyway.
I agree with you also that cleaning lenses inproperly is a cause for
scratches and damaged coatings.
There are plenty of professionals who fail to see the value of proper
cleaning.
I disagree, however that frequent cleaning is not good for a lens. Modern
coatings, unlike the old Planars', are very tough. Cleaning a lens with a
brush instead of cloth and liquid may be sufficient in most cases (a clean
brush causes no damage), but a clean lens is much preferable to a dirty one
for obvious reasons.
Joe Codispoti
To: camera-fix@yahoogroups.com
From: Steven Bailey stiltonkopf@yahoo.com>
Date: Fri, 21 Dec 2001
Subject: Re: [camera-fix] Yellow Lens. Hopeless?
--- Mark Overton mark@sdd.hp.com> wrote:
> Dude wrote:
> > I stumbled upon a nice Zeiss Jena Pancolar 50mm
> f/1.8. It has these
> > problems:
> >
> > 1) Focusing takes a lot of muscle. I could
> probably fix this.
>
> I fixed my identical Pancolar by applying some oil
> to the helical.
>
> > 2) The lens is very yellow when mounted on a
> camera (no, it's not the
> > camera--it's yellow on 3 different m42 cameras).
>
> Let's assume you don't have a yellow filter stuck on
> the front...
>
> This yellow cast is an *advantage* when shooting
> outdoors. If your
> subject is partly or fully shaded, or you're
> shooting under clouds
> or overcast, then your light is bluish, and
> uncorrected photos will
> have a blue cast. Blue sky creates blue light.
>
> Yellow is the complementary color of blue, so the
> yellow cast will
> counteract the blue skylighting, yielding more
> natural colors.
>
> I'm serious about this usage outdoors. However,
> shooting indoors under
> flourescent light will make the flourescant cast
> look *worse*.
>
> Somehow, the Canada Balsam glue between the cemented
> pairs has yellowed.
> I'll guess it's due to exposure to excessive heat or
> light (lens was left
> in the sun?).
>
> When you look through the lens (with it off the
> camera), is the yellow
> cast evenly distributed, or is it blotchy? I have a
> Vito B whose rear
> cemented pair has contaminated glue, giving it an
> uneven gray cast around
> the perimeter.
>
> Mark Overton
I have not only a 50 1.8 Pancolar (zebra mount) but
also several Russian Jupiter lenses for Kievs and
Zorki/Fed/Leningrad which exhibit the yellowness you
describe, some to a very great degree. Perhaps this is
ideal for B&W; film, but I find the outdoor results
with color film - consistently - unusually warm and
plan to experiment with a light blue filter, which was
included with one of the lenses. A UV or skylight is
definitely overkill.
I don't know if it's a matter of concern or curiosity,
but I read a thread about radioactivity in lenses
(Lanthanum and Thorium to name a couple)and yours is
one of them. You could find this thread by searching
under "Pancolar" on Yahoo! - at least that's how I
found it. The amount of "heat" may be negligible, but
enough to turn one of the elements totally yellow.
Steve (stiltonkopf)
To: camera-fix@yahoogroups.com
From: Mark Overton mark@sdd.hp.com>
Date: Sat, 18 Aug 2001
Subject: Re: [camera-fix] painting lenses
Kelvin asks:
> I have a takuar 55/2 with a slight nick and scratch on the lens front element.
>
> am thinking of painting that spot black to reduce the chance of flare.
> Will a black marker do, or else what sort of black paint is best?
The tip of a marker pen is probably too large, and would paint much
more than the scratch. I suggest using a negative-retouching brush,
or a tiny artist's brush, and paint on thinned black enamel paint.
Use reading glasses or something so you can focus very close, and
brace your hands by leaning them against something so you can apply
the paint precisely.
HTH,
Mark Overton
To: camera-fix@yahoogroups.com
From: Ron Schwarz rs@clubvb.com>
Date: Sat, 18 Aug 2001
Subject: Re: [camera-fix] painting lenses
>The tip of a marker pen is probably too large, and would paint much
>more than the scratch. I suggest using a negative-retouching brush,
>or a tiny artist's brush, and paint on thinned black enamel paint.
>Use reading glasses or something so you can focus very close, and
>brace your hands by leaning them against something so you can apply
>the paint precisely.
Might want to clean the scratched area first, maybe plastic pipe cleaner
(the solvent you use prior to applying the cement to two pieces of pipe)
would do. If there is any grease or oil, even a one-molecule layer, it
could prevent good bonding of the paint to the glass.
From: "eMeL" badbatz99@hotmail.com>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Sat, 8 Sep 2001
A1 Shooter a1shooter@email.adr> wrote
> At best, a scratch will add flare to the photo, especially around
> highlights. This is what a "cross screen" does. The old
> technique of filling a scratch with black ink or paint will help
> to minimize the flare but there will still be some light loss.
>
> In no case is it possible for scratches to have no effect on
> image quality. Those sellers who make such claims are
> either lying or misinformed.
>
> It is possible for small flaws to have "no major effect"
> for whatever that's worth....
Eee...I'll give you a hundred bucks (a figure of speech, of course...) if
you detect *any* loss of image quality with my 17 mm Canon FD lense which
happens to have a itsy-bitsy scratch on the front element (the effect of
ill-fitting lens cap.)
A friend of mine owns a pristine specimen of that very lense and we tried
and tried and tried to make my lens show *any* imperfection even in a scene
consisting of a very strong light shing at the lens, and so far no dice...
Minor scratches on the front surface - if limited to the coting and not
reaching the glass - are *really* benign.
Michael
From: "Ahriman" ahriman@nospam.com>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Sun, 9 Sep 2001
"John R. Cooper" john@jrcooper.com> wrote
> I see a lot of used lenses being sold on eBay that have small
> scratches on either the front or rear lens elements, but the sellers
> insists that they doesn't affect image quality. How is this possible?
> How can light refraction NOT become scattered when passing through a
> scratch?
>
> Are these eBay sellers trying to foist flawed lenses on an
> unsuspecting public, or is there a valid explanation for their claims?
>
> Thanks,
> - John
>
It seems to depend a lot from lens to lens and scratch to scratch. I had a
Carl Zeiss Jena 29mm f2.8 with a tiny scratch on the front element just to
the right of the centre, and it flared horrendously (compared with a clean
specimen) in even vague light, and sharpness was affected quite heavily.
However, on my Pentax Super-Takumar 35mm f3.5 there is a nasty chip in the
dead centre of the front element, yet images are pin sharp across the board,
and there is only the natural flare I would expect from an uncoated or
single-coated lens. Weird.
Ahriman
From: "Joseph Meehan" sligojoe@hotmail.com>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Sun, 09 Sep 2001
Most of the time it will not show up at all. When it does it generally
shows up a as a little flair which will cause a little reduced contrast,
generally localized in one part of the image. Even when it does cause a
problem, it is difficult to see.
Even at that 90% of the potential problem can be eliminated by darkining
the scratch with a little ink or paint. That will eliminate the flair
problem. I have found that a little India ink in a dip pen works well. We
did it all the time when I worked at a photo studio. The India ink and dip
pen were always handy as we used them to mark the 4x5 - 20x24 negatives we
used.
--
Dia 's Muire duit
Joseph E. Meehan
"John R. Cooper" john@jrcooper.com> wrote
> I see a lot of used lenses being sold on eBay that have small
> scratches on either the front or rear lens elements, but the sellers
> insists that they doesn't affect image quality. How is this possible?
> How can light refraction NOT become scattered when passing through a
> scratch?
>
> Are these eBay sellers trying to foist flawed lenses on an
> unsuspecting public, or is there a valid explanation for their claims?
>
> Thanks,
> - John
>
From: christophe.pinson2@freesbee.fr (Christophe Pinson)
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Sun, 09 Sep 2001
>> How can light refraction NOT become scattered when passing through a
>> scratch?
Basically , we all spontaneously think that this or this part of the
lens will give this or this part of the image. It's wrong : every
point of the lens gives a full image, the center giving an image with
infinite dof, a point on the border giving a zero dof image. What you
get is the sum or the superposition of these images
So , a scratch is a zone that gives no image, or a blurred image, or a
shadow. These are delayed among the others, and thus affect them to a
certain point, but you won't find the scratch on the final image.
In fact, a film of grease or fingerprints on the lenses are far more
dommageable than a scratch, because the surface ( the number of
"points " affected ) is much larger, so there are more blurred images
in the final mix.
From: David Littlewood david@nospam.demon.co.uk>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Sun, 9 Sep 2001
John R. Cooper john@jrcooper.com> writes
> I see a lot of used lenses being sold on eBay that have small
>scratches on either the front or rear lens elements, but the sellers
>insists that they doesn't affect image quality. How is this possible?
>How can light refraction NOT become scattered when passing through a
>scratch?
>
> Are these eBay sellers trying to foist flawed lenses on an
>unsuspecting public, or is there a valid explanation for their claims?
>
I mostly agree with Christophe's comments.
I suspect that many more pictures have been spoiled by fingerprints on
the lens than by modest scratches on the front or rear elements, and
that many more lenses have been badly degraded by a host of micro-
scratches from clumsy cleaning than from single visible scratches.
For a lens wide open, a scratch on the front element will normally only
cover a tiny percentage of the surface. This percentage will *normally*
be significantly higher if it is on the rear element, simply because the
rear element of most lenses is much smaller in area. If the scratch is
in the centre, it is possible that this percentage will increase
dramatically as the lens is stopped down.
I believe the kind of micro-scratches which are caused by vigorous
cleaning of dusty lenses, or using grimy cleaning cloths, will be more
damaging. They are barely visible to the naked eye, and reduce contrast
quite markedly.
In the end, you have to make your choice: a cheaper lens which will
probably perform as well as any other, or a cosmetically perfect one for
more cash. At least if the seller tells you, you are not having anything
foisted on you. I think Joseph Meehan's idea is the best one; if I had
any scratched lenses I would try it.
--
David Littlewood
From: bachchaconne@my-deja.com
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Mon, 10 Sep 2001
Seems the size and location of the scratch will determine the effect:
http://www.leicagallery.com/scratchedlenses.htm
However, according to this page, scratches on the_rear_element doesn't
matter as much. Perhaps a typo.
I would think that multi-coated lenses from well-known makes will
suffer less than those with single or poorer coating, if other things
are equal.
Andrew
On Sun, 09 Sep 2001 doregan@attglobal.net wrote:
>It depends on the size and location of the scratch. For a light, five
>scratch on the perimeter of a front element, I'd say you'll never noyice
>it. A deep gouge in the center of the front element? I'd avoid it. I'd
>avoid virtually any lens with a defect on the rear element.
>
>"John R. Cooper" wrote:
>>
>> I see a lot of used lenses being sold on eBay that have small
>> scratches on either the front or rear lens elements, but the sellers
>> insists that they doesn't affect image quality. How is this possible?
>> How can light refraction NOT become scattered when passing through a
>> scratch?
>>
>> Are these eBay sellers trying to foist flawed lenses on an
>> unsuspecting public, or is there a valid explanation for their claims?
>>
>> Thanks,
>> - John
From: "eMeL" badbatz99@hotmail.com>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: How can lens scratches NOT affect image quality???
Date: Sun, 9 Sep 2001
Tony Polson no.email@please.com> wrote
> This may or may not be apparent to the photographer. If you are using
> consumer-grade film and having it developed at a consumer-grade minilab,
> you probably won't notice. But try having the negs enlarged. You will
> probably see a difference.
>
> If you use slides and view them with a top quality loupe the difference
> becomes even more apparent.
How does a 4x, 8x and 15x loupe sound? Color balanced light table? 20x
enlargements (film - Ektar 25 and Tech Pan!) ???
It was an obsession for me for quite a long time. Still cannot see any
difference. But it is just ONE shallow scratch on the front element of an
otherwise pristine lens.
Sooo...in photographic PRACTICE (even in the rarified air of high end
equipment and process) a single shallow scratch on the front surface of a
lense simply does not matter.
Michael
From: Karen Nakamura mail@gpsy.com.invalid>
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Chip on rear element
Date: Fri, 14 Sep 2001
At most, it'd cause a bit of contrast reducing flare. Try taking some
photos of a bare light bulb in a dark room at f8 or 11. Look at the
shape of the flare patterns. If they seem to be consistently strangely
shaped in ways that have nothing to do with the orientation of the
lightbulb to the lens, but do seem to have something to do with the
orientation of the lens to the film, then you might have a problem.
Otherwise, just use some india ink to fill in the scratch (a black spot
is better than a white one).
- Karen
chrisplatt@aol.com (ChrisPlatt) wrote:
> I was told the rear element of the lens was chipped, but $40 for
> an SMC Pentax 85mm f/1.8 K-mount MF lens is a great price.
> And Pentax parts still has the rear lens group in stock for $35.
> Even with the cost of installation this lens would still be a bargain.
> The store had a good return policy so I went ahead and ordered it.
>
> Now that I have the lens in hand, I find that the chip is much smaller
> than I had imagined; it is in fact only about the size of a pinpoint
> and approximately the same depth. It is just slightly off center.
> The lens is in good shape otherwise, a solid 8 and working well.
>
> How and to what degree will such a chip to affect image quality?
>
> Should I spend $60-70 to repair, while the parts are still available?
>
> TIA,
> Chris
>
From: rpatrasc@cs.uwaterloo.ca
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Scratch on lens - help!
Date: 7 Dec 2001
Brian Ascot bascot@hotmail.com> wrote:
> depends where the scratch is - only a problem if in the center of the lens
I will very much doubt that you will see any difference. The reason I say this
is because a while ago I bought a Hasselblad 500c with the normal 80mm Zeiss
lens on it from eBay. The lens was described as clean, clear and free of
scratches. When I opened the lens from the plastic wrap, what do I see? A
scratch of about 2mm right in the middle of the rear element. And it was
deep enough to catch on the cleaning cloth. So I agonized over it and the
seller replaced the entire rear group at no cost with one without a scratch.
However, I had taken pictures (both slides and negatives) with the scratched
lens and compared them with those taken with the good lens and I was not able
to see ANY DIFFERENCE in contrast, flare, or sharpness. And this with a
scratch on the rear element, which is supposed to be more troublesome than on
the front.
I guess you have to have it happen to you to get over such a thing, because
ever since then, I do not clean my lenses as often, and I will consider
buying a lens with soft wipe marks on it. Something which I wouldn't have
done before the episode with the Zeiss lens. It is not uncommon that
excellent lenses have tiny bubbles of air in the front element (happens to
Leica too) yet they will take great pictures.
In summary, if you can, just ignore it. If it does bother you psychologically,
then the only thing that will make you happy is to replace the front element.
Hope this helps,
Relu.
To: camera-fix@yahoogroups.com
From: rolohar@aol.com
Date: Fri, 28 Dec 2001
Subject: [camera-fix] Re: Minolta SRT-101
Kurt Weiske
Thomas Tomosy in "Camera Repair and Maintenence, Vol.I" talks about how the
prism assembly on the SRT-101 can become dull and cloudy because the Canada
balsam cement yellows and dries out.
He says the cracked, cloudy, yellowed glue restricts light transmission and
fools the meter into reading low, thus causing overexposures. He gives
instructions on how to get to the pentaprism assembly. There are two auxilary
prisms cemented to the top of the pentaprism that transmit light to the Cds
meter cells. He also gives a lot of other information about working on the
camera.
If you would like to see the pages from the book, let me know and I will post
them in my FTP space where you can access them. I have not worked on this
particular Minolta model.
Good luck on your repair
Roland F. Harriston
Date: Sat, 29 Dec 2001
To: hasselblad@kelvin.net, hasselblad@kelvin.net>
From: Jim Brick jim@brick.org>
Subject: Re: [HUG] Questions about 150/4C
My best C lenses had bubbles. Back then the really good glass could not be
made without some bubbles according to Zeiss. Zeiss had a big write-up
about this way back then. My 50 C certainly had its share of bubbles. And
was a stellar performer. I hope my new/used 50 FE (which I haven't used
yet) is as good a performer.
Jim
Tourtelot wrote:
>I just got (what I think is) a nice 150/4 C. In the"old days" did some
>Zeiss lenses show up "flawed." This lens seem to have a cluster of bubbles
>trapped in one of the elements. It doesn't look like classic fungus (not
>spiderwebby) and it seems to be a little globe shape so I don't think it's
>separation. Seems to shoot fine and at my budget, I plan on using it for a
>long time. I will send it in in about six month to have it CLA'd, but
>shutter speeds are good. Just curious.
>
>D.
Date: Sat, 12 Jan 2002
Subject: Re: [HUG] 150 Sonnar with scratch
From: Peter Rosenthal petroffski@mac.com>
To: hasselblad@kelvin.net>
> I was recently traded some exercise equipment for a 150 Prontar f/4 CF
> Sonnar lens that has a small scratch (less than one millimeter) in the
> center of the rear element. The scratch actually goes into the glass a
> bit. Otherwise the lens is mint. The scratch has yet to show up on my
> chromes, but it bugs me to no end just knowing that the scratch is
> there. Opinions on whether or not it is worth getting fixed?
>
> Lewis Weber
Scratches on the rear element are somewhat more serious than on the front
element. Smaller apertures will tend to enhance any scratches, or dust for
that matter, and what we're dealing with is scattering of light. Reduced
contrast. Trying to quantify it is just about impossible. It sounds nuts on
the surface but if you could just fill the scratch with black crayon or
paint you can avoid the scattering but there is then a small issue with
refraction. Filling the scratch really does help. The refraction (reduced
contrast) is minor compared with the open scratch. It sounds like the real
problem is, "it bugs me no end." There is no fix for this except time. I
don't have the cost of a rear element in my head but it should cost no more
than $120 if my memory is OK (not much chance of that).
My guess is it's not worth getting fixed but there is that "it bugs me no
end" thing. I'd use it for a couple of months and see if you feel better
about it. Then decide. It's a tough one for sure!!
Peter
--
Peter Rosenthal
PR Camera Repair
111 E. Aspen #1
Flagstaff, AZ 86001
928 779-5263
From nikon mf mailing list:
Date: Thu, 17 Jan 2002
From: Rick Housh rick@housh.net>
Subject: Color cast of lens
I didn't take the time to search the archives, but I do remember that we
had a discussion some time ago about a problem some were having with lenses
imparting a distinct color cast to slides.
I chanced on a 35mm f/1.4 (converted) AI lens on ebay which the seller says
imparts a very distinct yellow shift to everything. He said he had sent it
to Nikon Canada for diagnosis and possible repair, and was informed by them
that the problem was caused by some of the coating having been removed by
cleaning, that it wasn't repairable, and that it was a problem on some of
the early samples of the lens.
Just thought this might be of interest to those who had raised the issue
earlier.
Here's the lens on ebay:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item;=1320554177
- Rick Housh -
From nikon mf mailing list:
Date: Thu, 17 Jan 2002
From: "bruce_a_conklin" bruce_conklin_99@hotmail.com>
Subject: Re: Color cast of lens
--- In NikonMF@y..., Rick Housh rick@h...> wrote:
> a problem some were having with lenses
> imparting a distinct color cast to slides.
>
I have dabbled in the past with Pentax cameras, another altogether
usable 60s-70s era camera system. The 50mm f1.4 Takumar (and some
other fast Takumars of the day) were constructed using rare earth
elements to enhance light transmission and help the designers achieve
the desired lens speed. Unfortunately, the rare earth glasses have a
pronounced aging phenomena of yellowing, rendering them difficult to
use for chromes. Could this be a partial explanation of some Nikkor
yellowing?
There was a fellow on the Spotmatic list who posted photos of his
corrective procedure for the yellowing problem. He placed the lens
on a stump.....then whacked it with a 16 pound hammer. I believe he
called the procedure "Shower of Glass". As a testament to the lens
construction, the lens body was distorted very little, although glass
did fly everywhere.
BTW, I HAVE repented and have only Nikons any more. ;=}
Bruce Conklin
Sacramento
From nikon mf mailing list:
Date: Fri, 18 Jan 2002
From: "bruce_a_conklin" bruce_conklin_99@hotmail.com>
Subject: Re: Color cast of lens
--- In NikonMF@y..., monotreme@w... wrote:
> Wouldn't it be easier to just use a filter?
Excellent question. The problem is compounded by yellowing becoming
more pronounced over time AND by not progressing at the same rate in
all lenses. So you just can't predict how much correction a given
len will need. I have had lenses which showed virtually no shift and
others that were quite yellow.
B&W; prints and color prints can be corrected with custom printing.
Slides are the real problem.
Bruce Conklin
Sacramento
From nikon mf mailing list:
Date: Thu, 17 Jan 2002
From: "Mel" mgreg@intcon.net>
Subject: Re: Re: Color cast of lens
----- Original Message -----
> I have had lenses which showed virtually no shift and
> others that were quite yellow.
>
> Bruce Conklin
> Sacramento
Over the period of too many years to really brag about, I have collected
many MF and AF lenses from the earliest Non AI to the D series. My manual
lenses show the greatest variance in coating colors. A 43-86 Zoom
exhibits a yellowish color as does a 28mm 3.5 and this worried me as I
started shooting slides with these lenses years ago and thought the
coloration would carry over to the slides. If it does, I can not see it.
In fact, some of the best slides for apparent contrast and apparent color
are from these two lenses. I have one lens with sort of a purplish hue
and the rest exhibit little if any colorization.
Perhaps my sense of color is not as great as some or perhaps my ideal as
far as color in a slide is different but search as I might for a fault, I
find none.
Mel
from leica topica mailing list:
Date: Fri, 16 Nov 2001
From: Jim Brick jim@brick.org
Subject: Re: Nocti Vignetting
Ted Grant wrote:
>And we wont tell them about the little zit in the glass of my 15mm R lens I
>discovered the other day. Oh well life is just awful some days. ;-)
>
>I have no idea how long it's been there, but probably happened when I stuck
>it in my pocket during a quick lens change and there happened to be
>something else in the pocket with it.
>
>Hey I'm not loosing any sleep over it as it's not effecting the images at
>all. Why it might even be improving them. ;-)
>ted
Ted,
You and I both know that a zit or two, scratch, small hole, whatever, won't
in any way effect your images.
If the giant bubbles in my early Zeiss lenses didn't effect anything, a zit
or two sure as hell won't.
To all LUGgers:
But dirt and grime will since it is evenly distributed over the whole
lens. It effects 100% of the light rays. Not just .00000001% of the rays
as a zit or bubble will. It makes fine detail disappear. Turns your film
camera resolution into digital camera resolution. Keep your lenses clean.
Go to LUGger Joe Codispoti's site and partake.
http://www.clearsightusa.com/
Great great stuff!!!
Photographed any welders lately Ted?
:)
Jim
From nikon mailing list:
Date: Sun, 15 Apr 2001
From: David Lew dlew2@yummysushi.com
Subject: Re: [NIKON] Re: Dust & Scratches with Nikkor 28-70 f/2.8 AFS?
We're basically talking about the new AFS lenses that are assembled in
Japan. I received 2 AFS with scratches and 1 80-200 the one before the
AFS with scratches too.
Ed Mathews wrote:
> Do these problems people are talking about have anything to do with where
> the lenses are assembled? Or, is it the glass itself? I understand it's
> common these days to have lenses assembled in places like China, Taiwan,
> Korea, in order to save money on labor. Are they scratching the elements
> during assembly? I also have heard that Nikon does not manufacture their
> own glass, but rather (like most camera/lens manufacturers), they design the
> lens and order the glass to fill their specifications. Could this be a
> problem at the glass supplier level? I can't imagine that all of a sudden
> Nikon Japan has simply lost quality control.
>
> Thanks,
> Ed
From nikon mailing list:
Date: Mon, 16 Apr 2001
From: "Steve Tyler" tylers@shoalhaven.net.au
Subject: Re: [NIKON] Re: Dust & Scratches with Nikkor 28-70 f/2.8 AFS?
Ed Mathews: Finished his post by saying,
I can't imagine that all of a sudden
Nikon Japan has simply lost quality control.
As far as I am concerned, this is not all of a sudden,
but rather over the last few years or so, the decline
has been slow but sure. They once made their own glass
and lenses and were fanatical about QC, but now they
could not give a rats' proboscis about it, or so it seems.
It may be an urban myth, but I have gleaned from this
list and heard it else where that Nikon lost their top
three lens designers, some time ago, over the QC issue,
and they are now in Tokina's employ.
Steve. [bah - humbug]
From nikon mailing list:
Date: Mon, 16 Apr 2001
From: "Phil" pjh@bellsouth.net
Subject: Re: [NIKON] AFS 28-70 2.8 scratch/quality control issue?
Hi,
After reading about all these scratches that are present on so many of the
AF-S 28-70/2.8, I decided to check mine thoroughly and I'm pleased and proud
to report there are no scratches of any kind on my lens..... I feel like the
value of my lens has now risen 50% because it is one of the few without
scratches.... :-) Just kidding.......
Have Fun, Phil
North Palm Beach, FL
From kiev mailing list:
Date: Fri, 14 Dec 2001
From: Kevin Kalsbeek krkk@earthlink.net
Subject: Re: Lens Bubble?
Eric,
The bubble in the Flektogon with hurt nothing!! Forget it! Many years ago,
lens bubbles were very common until a Japanese engineer in the early 1950's
came up with a special crucible the virtually elimated them.
A bit of dust will hurt nothing either!!
Kevin
From nikon mf mailing list:
Date: Fri, 16 Nov 2001
From: "Riccardo Polini" RIPOLIN@TIN.IT
Subject: OT: Inhomogeneous sharpness across the frame
Hi all-
I have recently tested a (not Nikon) 80-200/2.8 zoom. I did shoot some test
rolls at different apertures and at different focal lengths. Then I
scrutinized the slides by 8X loupe.
Well, I observed a rather strange sharpness loss at 200mm and both f/2.8 and
f/4 in a region between the center and the frame edge. The reduced sharpness
was not attributable to depth of field issues, nor to misalignments of the
camera back; in fact, with the same camera, a AIS 80-200/4 @ 200 mm f/4
doesn't show the same "local" sharpness loss.
I think that it might be attributed to misalignment of some glass element
inside the zoom, but I would greatly appreciate hearing your opinions about
that strange behaviour and if you've noted similar inhomogeneous sharpness
issues with Nikkor lenses.
TIA,
Riccardo Polini
http://space.tin.it/arte/ripolini
ripolin@tin.it
From nikon mf mailing list:
Date: Sat, 17 Nov 2001
From: tpeach@gte.net
Subject: Re: OT: Inhomogeneous sharpness across the frame
--- In NikonMF@y..., "Riccardo Polini" RIPOLIN@T... wrote:
> I think that it might be attributed to misalignment of some glass element
> inside the zoom, but I would greatly appreciate hearing your opinions about
> that strange behaviour and if you've noted similar inhomogeneous sharpness
> issues with Nikkor lenses.
> TIA,
My one foray into KEH "Ugly" lenses was a 20mm f/2.8 AFD. The lens
passed my usual visual inspections. When I went out to run a test
roll through it, I noted an odd behavior: when focusing, the lens
"point of aim" changed fractionally somewhere in the travel
(particularly noticable with AF since the camera is racking the focus
rapidly while I hold still).
I made sure to include some "field flatness" subjects on the test
roll. At infinity, the sharpness was almost acceptable, but close in
the left half of the frame was noticably softer than the right. I
assumed that one or more elements was not being held in the correct
position, and that it was off-center.
I returned the lens to KEH without incident. In my conversation with
them, they educated me that "ugly" to them means that the lens has
some problem; it's intended to be purchased by someone who will either
live with that problem or repair it themselves.
-Todd Peach
tpeach@gte.net