Precision Camera and Lens Repair
Email PCL
John Van Stelten
1017 S. Boulder Rd.
Suite E-2
Louisville, CO 80027
Ph: 303-665-6640
Fax:303-665-3803
EMAIL: john@focalpointlens.com
Paul Ebel
W230 Terrace St. POB 86
Spring Valley, WI 54767
715-778-4372
Lens Services:
medium format lenses, cameras - CLA $58
view lens CLA $36
speed recalibrations $16
recement view lens elements $55
Rangefinder adjustments $45
brilliant focus screens $95
warranty - one year (shipping extra)
See Focal Point in the USA which also recoats lenses, repolishes them, handles fungus and hazing problems, and so on.
I have been advised that Ultraflat Corp. will
grind and polish and recoat lenses, a service they provide primarily for
the movie business. They provide a free estimate and examination
service.
Edmund Optics (formerly part of Edmund Scientific Inc.)
can provide a variety of coating services on a custom per-job basis. See
posting to learn more about:
http://zzz1.net/rd/rd.asp?ZXU=845&ZXD;=86085 - visit our website for more information!
Visit http://zzz1.net/rd/rd.asp?ZXU=845&ZXD;=86085 to read more about our coating capabilities!Our Coating Selection Includes:
Visible Broadband AntiReflection Near-Infrared Broadband AntiReflection Extended Broadband AntiReflection V and 2V Narrowband AntiReflection Single Layer MgF2 Broadband High Reflectance Narrowband High Reflectance (Notch Filter) Dielectric High Reflectance Aluminum Coatings Silver and Gold Dielectric Laser Mirror Dual Laser Line Mirror Hot and Cold Mirrors Broadband Visible Beamsplitter NIR & Telecom Non-Polarizing Beamsplitter Non-Polarizing Coatings Brewster Plate Polarizing Broadband and Laser Line Cube Polarizers High Efficiency Telecom Polarizing Filters Long Wave and Short Wave Pass Bandpass
For Australia resources, try:
Longman Optical
Ian Mansfield
Technopark Centre, Dowsing Point
Glenorchy Tasmania 7010
Ph. 03 6233 5505
45 years in business, camera lenses repolished, doublets recemented,
coated with MgF, aluminising of mirrors, with silicon monoxide
overcoating, collimation. [from posting]
How is the cost of repair computed?
The above lab will give you an estimated cost if requested. Some users
report being charged $15 to $20 per surface for lens coating. That sounds
cheap, but even a simple five element lens will have ten optical surfaces
to be coated. Refiguring a scratched lens surface may add even more to
your cost. Naturally, all this precision optical work carries a high
hourly wage and huge overhead expense that you have to pay for too.
Is there any danger the lens will be lost or destroyed?
Yes, there are always risks. Older lenses may have stress lines or hidden
fractures which will become all to evident when removed from their
optical adhesive mounting. The lens element can literally crack and
fall apart. The risk of a
broken lens is reportedly very small, but it is still a risk.
What sorts of problems can be fixed with lens polishing, refiguring,
and recoating?
- Most lens killing problems can be fixed with this radical lens surgery,
including:
- scratched lens
- scratches in coating
- flat spots worn in lens
- etched fingerprints or other spots
- fungus growth etching of lens elements
- separation of edges or center of lens
Do each of the above always involve an expensive process?
No, obviously not, as it depends on the nature of the problem. A light
fungus growth problem might be easily killed with some ultraviolet light
and a bit of disassembly and cleaning. A thumbprint might be removed from
a lens front coating, and a new coating reapplied only on that one surface.
But even such minor repairs will involve a good bit of skilled optical
testing and alignment to ensure required performance is retained and
achieved. The major costs of disassembly, testing, and re-assembly are
still the big cost drivers, so even minor repairs can still cost a lot.
Why are there so few recoating facilities available?
Doing the job right takes a huge investment in trained staff and
facilities. One of the biggest limitations is the lack of test plates
required to check the lens curvature at a very high degree of accuracy.
For each lens surface, you require a different test plate. Placing the
lens in contact with the test plate in an optical setup shows fringe
patterns. These fringe patterns reveal the accuracy or trueness of the
lens curvature to the desired lens figure shape.
Now recall that each
lens may have up to a dozen optical elements, each with front and rear
curvature that has to be verified and maintained. If any of these
surfaces are off even a few wavelengths of light dimensionally, your lens
may lose sharpness, contrast, and overall performance.
Now recall all the lenses out there, and the tremendous number of optical
designs and related lens sizes and curvatures in use over the last fifty
years of lens manufacturing and design. Think about all those former
manufacturers who have gone out of business. Imagine trying to get a
stock of test plates, accurate to wavelength of light dimensions, to get
into this business. Now you see why so few lens repair and recoating
facilities exist today.
It is also worth noting that the lens doesn't stand alone. The mechanical
mounting also has to be right and properly aligned, usually to dimensions
measured in ten-thousandths of an inch. So an optical lab is no good
unless you also have all the mechanical equipment and knowledge needed to
preserve the mechanical support and operation of the optical elements.
Finally, even if the mechanics are great and the lens curvature and
coating restored to an ideal state, you still have to reassemble the lens
correctly. This process requires precise re-alignment of the optical
elements, usually on an optical bench. Moreover, some elements have to be
cemented together with precise thicknesses of optically defined adhesive.
These adhesives range from the older Canada balsam to the latest optical
adhesives that science can produce.
What about separation? discolorations?
Separation is usually the result of an older adhesive between the lens
elements literally separating away from one or more glued elements. The
process is most often seen at the
edges of optical elements cemented together. A related problem in older
adhesives is optical discoloration, often towards a yellow
coloration.
Both of these defects can often be fixed by disassembly of the len elements, cleaning, and reassembly with the proper thicknesses of the right optical adhesive, and in precise alignment. Again, this repair is one that many experienced lens repairpersons can perform using a relatively simple optical bench and tools.
Why isn't multi-coating recommended?
Cost effectiveness of multi-coating over single coated lenses is very
low. A typical glass to air interface might pass 65% of the light
striking it in an old lens design. Add one layer of optical coating, and
that figure will jump to 90% or more. Add three to five or even more
layers, and you only raise that figure to perhaps 95%. So it really costs
a lot more to get multi-coating, and the benefits usually aren't worth
the efforts.
How was optical coating discovered?
Basically, observations of older lenses revealed superior optical
performance over new lenses of the same design. This result isn't what
you would expect. Study revealed that the older lenses had developed a
thin layer of oxidation or discoloration which greatly improved their
optical light transmitting properties. This discovery was finally put
into widespread practice just before the second world war.
How is a coating applied?
Optical coatings are usually very thin layers only a few dozens of atoms
thick applied to the optical
glass surfaces. Early coatings used calcium or magnesium fluoride. The
coating is applied by deposition in a vacuum, requiring the use of a
large and expensive vacuum chamber device.
In commercial practice, large numbers of lenses are processed at once to
reduce costs. Proprietary formulas for coatings are kept secret by the
various manufacturers. Many improvements have been made, especially in
the hardness and durability of coatings over the last fifty years.
| Multi-coating Lens Colors |
|---|
| From Shutterbug Lens Flare Definitions and
Solutions by Don Garbera, p. 38, March 1989 The color of multicoating on your lenses indicates the complimentary color of light the lens' multicoating is designed to control; purple, red and blue reflections mean that the coatings are controlling green, blue and yellow light... |
How does multicoating differ from a single lens coating?
Multicoating is obviously multiple layers of coatings applied to the same
lens surfaces. But a single lens coating is a compromise of a specific
single thickness which is optimal for only one narrow band of visible
light. At other wavelengths, the optical coating is less than optimal.
Multicoating uses not only multiple coatings, but also different
thicknesses and even different chemistries of coatings. This approach
makes it possible for multiple bands or colors of light to be channeled
into the underlying optical glass, rather than reflected off the
surface. As a result, you get additional improvements in lens
performance with multicoating over a single coated lens design.
Are all modern lenses multicoated?
No, largely due to the costs involved and nominal benefits in some
applications. A good example is the popular series E lenses made by
Nikon, such as the 50mm f/1.8 series E lens. These lenses are reportedly
not multi-coated as one of their cost saving design features. The
relatively simple lens design and limited number of elements and air to
glass interfaces makes this tradeoff possible. A zoom lens, with many
more air to glass interfaces to scatter light, might not do as well as a
simpler lens if we failed to multi-coat the zoom lens optics.
Will coatings convert my older uncoated lens into the equivalent of a modern optic?
From Modern Photography, November 1980, p. 18, View from Kramer column:
My protars are beautiful, but they are anything but crisp. Their contrast
is less than impressive, and having the lens coated (as I have) doesn't
help much. Coating has no effect in the scattering of light within the
glass. It cuts down on reflections between air spaced elements, but the
lower contrast of old lenses is a result mostly of poor scattering
characteristics due to the qualities of the old optical glasses. Generally
they [older lenses] are softer and flarier than modern lenses.
What about prisms used in cameras and binoculars?
Most places that can recoat lenses can also resilver prisms used in
cameras and binoculars. Some older books even have techniques to
resilver prisms or mirrors, usually using various poisonous chemicals
(not recommended!). Really advanced telescope makers could even make
their own vacuum sputtering chambers to resilver mirrors. A large current
through a thin aluminum wire in a vacuum could sputter enough aluminum
atoms to coat a nearby telescope mirror or prism. As you can guess, this
is a lot easier than refiguring an optical lens, but no cakewalk either.
Robinson's
Antique Hardware and
Mirror Resilvering Site
What is the cost of a prism cleaning and resilvering typically
run?
It varys with the number of prisms. A simple, single prism cleaning and
resilvering might cost $50. A more complex set of binoculars, many of
which have four prisms internally, might cost $125 up. Coating the
two primary lenses on older binoculars might add $75 to that cost too.
Why are prisms such problems in older cameras?
Older cameras literally used silver to form the reflecting surface on the
prism. Silver oxidizes in air, as any housewife will attest. The coatings
are thin, and there is a tendency for thermal creep and other effects to
cause separation of the silvering from the underlying glass prism.
Why are newer prisms brighter, or what about aluminum prism
coatings?
More modern designs usually use a more robust layer of sputtered aluminum
instead of silver on prisms and mirrors. The aluminum is reported
brighter, cheaper, and longer-lasting than silver, with fewer separation
problems. Certain other reflective metal elements are also used, but
much less frequently that the cheaper aluminum coatings.
Astronomical mirrors are one popular type of mirror employing such front
surface aluminum coatings in modern designs. These soft aluminum coatings
are often protected from oxidation, smog, and air-borne dust and chemical
attacks by a thin layer of silicon dioxide.
Spectrum Astro Mirror
Recoating Services
Why are older lens and coatings more often scratched than new
ones?
The older coatings were softer than the very latest protected coating
technologies in most modern proprietary coating designs. Some sources
suggest a nitride or similar coating is often used to protect the softer
coatings (see below). A related factor
is that older glasses were often softer and more scratch prone than some
of the more modern glass formulas. So older lenses were more prone to
scratching both the coating and the glass itself.
A final factor is the much greater prevalence and use of protective UV filters on many amateur and even a few professional lenses. Multicoated filters are available, at substantially higher cost, with all the optical benefits that the above discussion would imply for them. A lens cap is probably even cheaper and better insurance against scratches too.
What about aluminum coatings for front surface
mirrors?
Front surface mirrors are often used, for example in the flip-up mirror
on most 35mm SLRs. These surfaces are very susceptible to destruction as
they are soft and easily scratched and etched by acids deposited with
your fingerprints. These same acids can also etch the front surface
coating and glass of lenses.
In general, it is much cheaper to replace the front surface mirror than
to get one repaired by cleaning and resilvering.
Much of the above has been abstracted from:
Roger Hicks' I Spy 8 Feb. 1995 pp. 26-7 British Journal of
Photography
Related Postings:
[Ed. note: A useful test tip from a noted camera repairperson]
Date: Mon, 26 Jan 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Cleaning Tessars
The way to tell if the lens has gotten hazy is to open the shutter and
shine a flashlight through the lens. Any haze or other crud in the lens
will become immediately apparent. Also check the finder lens. Haze there
will reduce the contrast of the finder image and make it harder to focus.
Cleaning the finder lens requires actually more disassembly than the taking
lens and will also require re-setting the correlation between finder and
taking lens. The is perhaps better left to a repair type person.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
[Ed. About scratches in glass and coatings:]
Date: Wed, 28 Jan 1998
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Re: German Glass
Peter,
Most optical glass is pretty soft stuff, particularly in comparison with
window glass and such. I don't think the German glass is necessarily any
softer than the Japanese stuff. Coating has a lot to do with it. In
many cases small scratches, which dealers like to call cleaning marks,
really
are not in the glass at all but in the coating. Modern coatings are much
tougher than older ones.
Bob
[Ed. Bob Shell is an experienced camera repairperson and
editor of Shutterbug magazine]
-----
Date: Wed, 28 Jan 1998
From: Mark & Sue Hubbard hubbard@humboldt1.com
Subject: Re: [Rollei] Re: German Glass
Peter,
I experienced the same thing, even to the point that the taking lens on my
old 2.8F Planar would scratch but the viewing lens did not. I agree with
Bob, however, that I think it was the coating that got scratched, and I
never noticed any effect on the pictures I took with that camera.
Mark Hubbard
Eureka CA
----
Date: Thu, 29 Jan 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re: German Glass
Early coatings were indeed soft. The very first ones used by Kodak, in
the late 1930's were so soft they could be removed by cleaning so were
applied only to inner surfaces. Lenses for the ill-stared Ektra camera
were coated this way. Really hard coatings probably weren't available
until the early or mid fifties. Curiously, I have a pair of Bausch & Lomb
Navy binoculars made in 1943 which are hard-coated on the outer surfaces.
I have seen other such glases which carried a warning lable (gone on mine)
saying they were coated and to be careful when cleaning.
I think the general disruption of things in Germany following the war
probably delayed the coating of German made lenses for a time.
The idea of coatings originated with H.D.Taylor, the inventor of the
Cooke Triplet, who noticed that old, tarnished lenses had higher
transmission than freshly pollished ones. Practical coatings had to wait
for the end of WW-2 and the application of modern high-vacuum deposition
technology.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Thu, 29 Jan 1998
From: Marc James Small msmall@roanoke.infi.net
Subject: [Rollei] LENS COATINGS AND ZEISS
Alexander Smakula combined the two elements necessary for successful lens
coatings, fluoride compounds and vacuum-depositing techniques. He began
this while completing his doctorate in an internship at the small German
optical works of Pohl; afterwards, he was hired by Zeiss, where he
completed the process in 1935. Zeiss began the commercial production of
coated lenses in 1937; I own a 1.5/5cm CZJ Sonnar in Contax RF mount
dating from 1939 which is both coated and marked with the epic red "T", and
I have a number of other Sonnars from 1940 and '41 in both Contax and Leica
mount which are so marked and coated.
Kodak and, I believe, Wollensak, developed the same process independently,
and at about the same time. Their error was their failure to see the
marketing edge it would provide. Zeiss trumpeted their coatings, but the
war cut off their sales.
After the War, Zeiss licensed the process selectively: clearly, Leitz did
NOT have access to it until the Zeiss patent expired in '55, though
Schneider and Voigtlander did. Thus, Zeiss lenses were HARD-coated from
'37 onwards and, by 1942, all CZJ production photographic lenses are so
coated. The soft coatings do exist, but these are on lenses from other
houses not privy to the Zeiss patent, where they had to resort to the drip
process which left a moist and soft coating.
Zeiss later pooled their expertise with Pentax to produce the first
multi-coating, used initially by Zeiss around 1968 on industrial and
scientific optics and by Pentax on camera lenses in early '71. Later 2.8F
Rolleis are known to exist with multi-coated lenses, though these lack the
"T*" markings; there may be 3.5F's which were multi-coated, as well,
though I am still awaiting the List Member who will report such.
Alexander Smakula emigrated to the US after the War and was the head of the
Physics Department at Harvard during the late 1950's and early 1960's when
this was one of the bases for the American nuclear-bomb programme.
Marc
msmall@roanoke.infi.net FAX: +540/343-7315
----
Date: Fri, 30 Jan 1998
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Re: German Glass
For those times when something more than just a wipe with a microfiber
cloth is needed, there are lens cleaning fluids. I have found two really
good ones, and a lot of rotten ones. The cheap ones are usually just
isopropyl alcohol with maybe a little detergent added. The good ones are
sold by Singh-Ray and Deutsche Optik. Both of these are used by the
military and by NASA for cleaning optics.
Bob
----
Date: Fri, 30 Jan 1998
From: Doug Braun dbraun@scdt.intel.com
Subject: [Rollei] More babble on coatings and cleaning
My humble observations:
I think coated lenses are more likely to remain in cood condition
because any damage done by cleaning is very conspicuous, even if
its effect on the image quality is minimal. But uncoated lenses
can basically be ruined by cleaning and still look "shiny". It's
only when you carefully shine light through them and look through
them that you can seen the zillions of tiny cleaning scratches.
I was looking at an older 2.8 in a shop last weekend, and I
noticed that the taking lens had too many cleaning marks to make
it really worth using (especially for the asking price...), but
the viewing lens was basically fine. Obviously the previous
owners were very concerned that that they get the most out of
their fine taking lens by always keeping it clean, and ended up
ruining it in the process. Because they paid less attention to
the taking lens, it survived...
Doug Braun
----
Date: Fri, 30 Jan 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] More babble on coatings and cleaning
Taking a pencil flashlight along when buying lenses or cameras is a good
idea. when shined through a lens it will show up any scratches or haziness
right away.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Multicoating
What exactly constitutes multicoating? More than one coat? Three coats?
I think there are as many definitions as there are doing coating. Some of
the earlier coatings were more than one layer.
Modern multicoatings have varying numbers of layers depending on the type
of glass, element configuration, lens design, etc. Someone at Leica told
me that some of their multicoatings have as many as 21 layers. I think
around 8 is more common, but lots of companies treat this as a deep dark
secret and won't tell you how many layers they use, or why.
Bob
----
Date: Sat, 31 Jan 1998
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Multicoating
First of all lens coating is a way to reduce reflection of light from
glass-air surfaces. The reflection happens because there is an abrupt
change in the index of refraction. By coating the surface of the glass
with a transparent substance with an index of refraction which is the
geometric mean between air and the glass and making the coating one quarter
wavelength thick at some wavelength, the reflection at that wavelength is
stopped because the index at each side of the coating seems to be the same
as the material next to it.
This idea works only at one wavelength. Because the range of visible
light is only about an octave (and photographic light only a little
wider)
a single coating optimised at the center of the band of interest will work
fairly well at the limits. In order to broaden out the band of wavelengths
(or colors) over which the coating is effective several coatings of
material of varying index and varying thickness can be layered. The wider
the bandwidth of the coating and the more even its effect the more
complicated it gets. At some level one reaches a point of diminishing
return.
For simple lenses with few glass-air surfaces a simple coating may be
sufficient. In fact, for these lenses coating may not make a big
difference. But for more complex lenses coatings can substantially improve
the performance of the lens. For some very complex lenses, such as the zoom
lenses used on professional television cameras, which may have twenty or
more glass-air surfaces multi-coating is absolutely vital for the lens to
be even usable.
You can get some idea of what kind of coating is on a lens by the color
of the residual reflection. Single coated lenses typically have either a
magenta color (when the coating is peaked in the green) or a straw color
(when the coating is peaked in the blue). Some multi coated lenses have
peaks at the two ends and look green. A truely broad band coating whould
have little residual reflection and it would be pretty neutral in color.
For those familiar with electronics the process is exactly that of
stepped distributed constant impedance matching sections or filters.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Mon, 02 Feb 1998
From: "Glenn Stewart (Arizona)" gstewart@inficad.com
Subject: Re: 50mm E lens and Multicoating (nikon-digest V3 #194)
Derrik wrote:
Anyway, my question: how does multi-coating change the quality of the
lens?
Derrik,
Lens coatings are for the purpose of reducing reflections of light at lens
surfaces.
Each time light either enters or leaves a lens element by passing through
the glass (or plastic) surface, some of the light is lost to reflection.
Single coatings were optimized for certain wavelenghts of light, with the
intention of reducing the reflections of colors which would look 'faded' in
the final photo due to much of their quantity being lost to reflection. The
material used for the coating dictates which wavelengths (colors) of light
will be passed more optimally by the lens. Generally, any particular coating
material only works for a narrow band of wavelengths. If the coating is
optimized to pass more red, the blue colors will still be less saturated
because more of the blue wavelengths are reflected at the lens surfaces.
In the early '70's, Asahi Optical (Pentax) came out with the first
multi-coated lenses. These lenses carried several layers of coatings,
each
of a different material and optimized to reduce reflections of different
wavelength bands of light. One is designed to reduce reflections of blues,
another for yellows, another for reds, etc. This makes the lenses more
'contrasty', and enhances the brilliance of the colors transmitted to the
film because more of each wavelength of light reaches the film, rather than
being reflected by the lens surface and lost.
Best regards,
Stew
Date: Thu, 29 Jan 1998
From: FortunkoC FortunkoC@aol.com
Subject: Re: [Rollei] Re: German Glass
Rolleinuts,
This discussion about "soft" glass is a little silly. It reminds me of the
endless discussions on the sister (Leica) group, which appears to be
dominated
by collectors. Like Richard Knoppow, I have never scratched a lens.
However, I
have seen and owned older Leica lenses with a lot of small scratches on the
surface. I attribute these to the fact that Leitz coating processes were
initially not as advanced as those at Zeiss'. My newer Leica lenses
appear to
have very tough coatings. Also, I use the new cloths to clean the lenses.
My feeling is that the newer coatings are generally tougher than the glass
they are deposited on. All of my SL66 lenses (from Zeiss) have great
surfaces,
even though the appearance of the barrels indicates that they have been
used
quite a bit.
This business about using filters to protect the lens is interesting. I
adhere
to the Leica/Leitz school on this subject. - Do not use filters unless you
have to, for example, to protect the lens surface from dust or sea spray!
Refraction is a real phenomenon that causes ray displacement and other
undesirable effects. Also, coatings may introduce unwanted effects. Yes,
I use
filters, but very sparingly. The R1.5 is useful here in Colorado, because the
sky is very blue most of the year, and I have two of them. Most of the time,
they serve to protect my lenses during travel. I bought them used for less
than a new Rollei front cap. (In fact, I prefer the older Zeiss front cap
design, because it is more secure. However, these are very hard to find.)
So, best of light,
Chris
rec.photo.equipment.medium-format
From: dmunroe@vcd.hp.com (Dave Munroe)
[2] Fungus (was: Hasselblad- Blemish inside lens ?)
Date: Tue Feb 10 1998
SportsPht wrote:
You should have that lens cleaned by a competent repairman. Chances are
high that it's a spot of fungus and if you don' t have it removed it'll
mar the coatings and could eventually etch the glass.
Ugh. Should I send it back to the seller ? Not sure if it's already etched
the glass. What causes this anyway ? It does look like fungus, now
that you mention this.
Fungus occurs in humid environments; I've been told that fungus will grow on
lens elements when the relative humidity is greater than 50%. In addition
to keeping the humidity level down, another way to prevent fungus is to keep
the lens exposed to open circulating air (this is preferable to it being
locked
up in a camera bag with the lens caps on). Tossing bags of silica gel in
the camera bag helps, too.
If the fungus is very small now, then it's not currently affecting image
quality where'd you'd ever notice it. However, fungus will grow unless it's
killed. I've heard that one way to do this is to put the lens (just the
lens, not lens and camera) in sunlight, being careful not to focus on
anything
that would catch on fire. I'm not sure how long to keep the lens in
sunlight
and I personally don't feel good about letting the lens get hot (due to
the
different expansion rates of glass and metal). I would like to hear
about
how to do this from someone knowledgeable.
Another, more expensive and professional way to do it, is to have a
repair
technician expose the lens to strong ultraviolet light.
These techniques will kill the fungus, but they won't remove any damage
that's already been done. In severe cases (i.e. the fungus has spread
over
a substantial part of the glass), an etched element may have to be
replaced.
-Dave
Date: Sun, 26 Apr 1998
From: Joe Berenbaum joe-b@dircon.co.uk
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Rollei E TLR 2.8 Planar
At 18:49 25/04/98 +0000, you wrote: >Hello, >I've got a rollei (TLR #1643352) that I bought a couple of years ago. >It takes great pictures and I would say it's a 9 condition. However, I >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 >directly under a bright light you can't really see it. Does anyone know >if these lenses can be re-coated or re-conditioned? Guess the worst >thing that could happen is that it will stay the way it is and I'll keep >taking pictures with it. Suppose it would be worth more to a collector >if it didn't exibit this condition. Would apprecate any feed-back from >the group about this. >Thanks. Roger
My 2.8F taking lens has this problem, and you can see the effect visually
really easily if you just breathe on the lens- the condensation seems to
outline the missing areas and it looks like a satellite picture of the
Phillipines. When I first noticed this I got lots of advice and information
and found that here in the UK I could get Rollei Service (Classic Repair
Services) to dismantle the lens and get the front element recoated for
something like GBP 100.00, and I also found out there were places that
would do it much cheaper if I could dismantle the lens myself and send them
just the front element! I also did a comparison of against the light shots
on both that camera and another 2.8F (both Planars) and found no
discernible difference in flare or contrast, or anything else. So far I
have not felt an urgent need to get it done.
Joe Berenbaum
Date: Mon, 27 Apr 1998
From: JJMcF JJMcF@aol.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] recoating lenses
My understanding of the recoating process is that the original coating is
ground off both front and back of the element, and it is then recoated. The
grinding has to be just right to avoid grinding any of the glass off. This
description has given me pause with respect to having any of my lenses
recoated, since it seems doubtful that optical grinding can be done by a
repair shop with the same precision as (for example) at the Zeiss works.
But I may be misinformed--does anybody know any more about recoating lenses?
Date: Mon, 27 Apr 1998
From: Terry Price terry@free.midcoast.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] recoating lenses
I do know that removing a coating is not something to be tried by an tyro.
I had a camera with a super sharp tessar lens that I had cleaned and
aadjusted by a local repairman who is fortunately no longer in business.
When I got it back he said, "The coating on the rear of the lens was rough
so I ground it off."(without asking me.) The camera has never been the
same since. It takes ok pictures but there is something missing in the
sharpness and contrast. Don't touch that coating!
Terry
Date: Mon, 27 Apr 1998
From: Todd Belcher toddmb@intergate.bc.ca
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] recoating lenses
The original coating is POLISHED off...not nearly as invasive as grinding.
As long as the curvature is the same, there will be negligable difference.
Once the curvature changes, then the lens will start exhibiting
abberations. The amount of stuff that must be polished off is
miniscule...or should be miniscule. These two fact are what I think that
you refer to when you speak of the precision.
todd
Date: Tue, 28 Apr 1998
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,
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.
----
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
"Christopher M. Perez" chrisper@vnd.tek.com wrote:
>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
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.
---
Richard Knoppow
Los Angeles, Ca.
dickburk@ix.netcom.com
From: Ron Wisner 72072.2763@CompuServe.COM
Subject: Re: Cleaning Older Coated Lens
Newsgroups: rec.photo.equipment.large-format
Date: Mon, 31 Aug 1998
Richard,
Perhaps this is an oversight, but you did not mention
"retro-coated" lenses, those which were not originally coated, but
coated by a third party after manufacture. Burk and James was the
most well known of those doing this, in which, by placing the
lenses in the vacuum chamber without the requisite heat to form a
good bond, they avoided the necessity of disassembling and
de-cementing the lenses. Unfurtunately, these coatings are not
resistant at all and are easily damaged. There are many of these
around, as they were coated by the thousands. To make matters
worse, they are especially susceptible to alkalies such as
ammonia, the very ingrediant in most lens cleaning fluids. Just
one application of Kodak lens cleaner can ruin a soft coating by
making it foggy. In those cases where a soft coating has been
irrevocably damaged I will make a pitch-lap using the lens itself
as the mold and simply polish the coating off. In these cases, no
coating is far better than a bad coating.
RW
From: "Ed Kirkpatrick" edkirkpatrick@erols.com
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Can Older lenses be (re) coated?
Date: Tue, 1 Sep 1998
They can but you should beware. Read Ron Wisner's article on just this
subject in last months issue of "View Camera", it is very complete and there
is excellent material on which you can base a decision to re-coat.
Ed Kirkpatrick
Rich Marti wrote
>I was wondering if there was anyone who coats older lenses. (or is this not >advisable?
From: "Michael A. Covington" covington@mindspring.com
Newsgroups: rec.photo.equipment.35mm
Subject: Re: ar coating damage question
Date: Fri, 28 Aug 1998
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.
--
Michael A. Covington / AI Center / The University of Georgia
http://www.ai.uga.edu/~mc http://www.mindspring.com/~covington
Date: Thu, 8 Oct 1998 19:07:19 -0400 (EDT)
From: Bob Shell bob@bobshell.com
Reply to: rollei@mejac.palo-alto.ca.us
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Coating lens
>At 07:16 AM 10/8/98 -0400, you wrote: >>>This exchange is from the Zeiss collector's list. The question has been >>>asked many times on this list as well, so I post it for your >>>information... >>> >>>---------------------------------------------------------------- >>> >>>Mario Nagano asked: >>> >>>> > I was just wondering if pre-war uncoated lenses like CZJ Tessar >>>> > lenses could be coated to improve their performance. >>> >>>and Yi-Chin Fang responded: >>> >>>> Dear Sir: >>>> As a Ph.D.candidate of optics design, MTF test and Zeiss >>>> collector, I have to say that it is not worthwhile to recoat your lens. If >>>> you want to recoat your lens, lens must be repolished it again, which >>>> might lose the accurancy of optical tolerance even decentering. The >>>> accurancy of optical tolerance plays the role of the wonderful >>>> classical-design optics lens made before 1975. >>>> The coating might reduce the inter-reflection and enhance the >>>> energy transmission. It works when the lens aim at the point light when >>>> photography work goes through. It is important but I have to say that no >>>> lens is absolutely perfect for every working condition even the great >>>> Zeiss modern lens. I suggest that you might avoid the back light >>>> photography with the lens without coating or only single coated. >>>> >>>> > Could it minimize flare problems? >>>> >>>> >>>> Impossible. As far as I'm concerned, flare is mostly due to >>>> aberration. >>>> >> >>Maybe this is a language problem, but I have no idea what he is talking >>about. Flare, more technically referred to as veiling glare, is caused by >>reflection of light from internal surfaces in the lens (lens flare) as well >>as by reflections inside the camera body. This has nothing to do with >>optical aberrations, per se, although some optical designs are obviously >>more prone to flare than others. >> >>Bob >> >> >> > Hi Bob, Spherical aberration can produce an overall haze which mimics >flare. This haze is dependent of the stop and goes away when the lens is >stopped down. Not all lenses exhibit this. I certainly agree that most >flare is from multiple reflections in lenses and a great deal is also from >light scattered around inside cameras, especially when the image circle of >the lens is much larger than the film and there is no means of baffling it >in the camera. Roleiflex TLR's and Rolleicords starting with the IV have >very effective internal baffling. Lenses should also have effective >internal baffles to prevent light from being scattered by the inside of the >lens mounting. I have, for instance, a couple of Ilex lenses which are not >properly baffled and have severe flare until stopped down enough to >vignette the edge reflections.
Understood. I know about spherical aberration and the veiling effect it can
produce. But that's technically not flare. But this fellow who says he is
a " a Ph.D.candidate of optics design, MTF test and Zeiss collector" says
that as far as he is concerned "flare is mostly due to aberration." As you
and I know, this is simply not true. Even allowing for spherical
aberration mimicking flare, this is a ridiculous statement. I'd say he
has a LONG way to go to get that PhD!!!
> As far as lens performance, coating will improve contrast somewht and >reduce ghost images in lenses which produce them, but has no effect >whatever on lens corrections. Coating does make practical designs with a >multitude of glass-air surfaces, many high performance modern lenses fall >into this catagory. > The improvement from coating a lens like a Tessar is modest.
Yes, we're on the same wavelength on all this (pun intended)!!
> I suspect that when a lens is considerably improved by coating or >re-coating it is because of something ancillary to the process such as >re-cementing or even thorough cleaning. Many lenses develop a haze over >their internal surfaces. This haze quite noticably reduces contrast. Since >the internal surfaces of lenses are often hard to get at these surfaces >never get cleaned. I hasten to point out that I don't mean only those >surfaces facing the shutter. Rather the sealed ones in the front of a >Tessar, for instance. Shining a flashlight through the lens will show up >this sort of thing right away.
Yes, it is a wonder what a good cleaning can do on some old lenses. Also,
lenses that are owned by tobacco smokers tend to pick up a coating of tar
on the external surfaces which can be hard to remove.
Have you had any experience with ROR lens cleaner? I see these people at
all the trade shows with their claims of 20% improvement in transmission by
simply cleaning off residual oil from lens surfaces. It's a good cleaner,
but I think the 20% is a great exaggeration.
Bob
Date: Thu, 8 Oct 1998
From: Dan Post dwpost@email.msn.com
Subject: Re: [Rollei] Coating lens
My question in re the exchange, "does it apply to lenses originally
uncoated?"
John Van Stelten polished and recoated a Schneider lens for me and it is
like new. I asked him about his process, and it involved polishing with
cerium oxide which apparently does not change the curvature of the lens- it
is then recoated.
When I got it back, the lens performed a whole lot better than before I sent
it off.
Now, this could be because this lens was designed to be coated- whereas a
lens design to be uncoated might suffer from the treatment.
Any ideas?
Sorry if I missed something in between, but MSN has had email disabled all
day!
Dan
dwpost@msn.com
Date: Thu, 8 Oct 1998
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Coating lens
Dan,
It is not what the polishing is done with but how it is done. Extremely
careful polishing with very fine abrasive, as Van Stelten apparently does,
can leave optical characteristics unharmed.
But for every lens I have heard of which has been successfully repolished,
there are three or four that were ruined.
I had a 150 mm Zeiss for Hasselblad repolished, recoated, and recemented
years ago by Ercona when they still did this sort of work, and the lens
came back as good as a new one. I then had the same people do another lens
and they ruined it! It would not focus sharply at any distance. It went
back to them several times, but ultimately it had to be junked.
On a lens with only a few elements coating may not make a great difference,
anyway. Some photographers, particularly large format shooters, say that
uncoated lenses actually perform better! This is because their somewhat
higher flare level cuts contrast and renders detail in shadows which would
otherwise be lost.
Bob
From Nikon Digest:
Date: Tue, 10 Nov 1998
From: "Roland Vink" roland.vink@ait.ac.nz
Subject: 4: Re: New lens coating?
> I picked up a new Nikkor 28/2.8D from my local dealer today and noticed the > lens has a deep green coating the same shade as the Nikon L37c filters. > All my other Nikon lenses have a light amber coating. Is the green coating > a new trend for Nikon? Just wondering.
I have a nikon catalogue which has a big double spread of all their
lenses. Most lenses have coatings from amber through to deep red. A few
are purple or bluish, and some are green. Various nikkor lenses have
different optical designs and probably use different types of glass, which
requires different coatings to ensure a consistent color balance.
Also, lens coatings have changed and improved over time, so newer lenses,
such as the AF-D 28/2.8 may have different colored coatings from earlier
versions.
Roland.
[Ed. From Nikon Digest]
Date: Sat, 14 Nov 1998
From: "Kok Hoo Lim" raphael@tm.net.my
Subject: [13] Nikon Lens coatings
Ray Tai asked in v04.n114:
" I picked up a new Nikkor 28/2.8D from my local dealer today and noticed
the lens has a deep green coating the same shade as the Nikon L37c filters.
All my other Nikon lenses have a light amber coating. Is the green coating
a new trend for Nikon? Just wondering."
Roland Vink commented in v04.n117:
" I have a nikon catalogue which has a big double spread of all their
lenses. Most lenses have coatings from amber through to deep red. A few are
purple or bluish, and some are green. Various nikkor lenses have different
optical designs and probably use different types of glass, which requires
different coatings to ensure a consistent color balance.
Also, lens coatings have changed and improved over time, so newer lenses,
such as the AF-D 28/2.8 may have different colored coatings from earlier
versions.
The early NIKKORs came with single coating which were usually yellow in
colour. Various multicoating were then made which resulted in colours like
blue, purple, and amber. In 1971, Nikon introduced what it called NIC (Nikon
Integrated Coating involving the application of between 3 to 10 coatings of
each individual element in a vacuum the duration of which was adjusted by an
electric current). The duration of coating of each element is between 30-45
min depending on the number of coating. The elements are then removed from
the vacuum chamber and the edges painted black before assemby into the final
lens. This process of NIC gives the green colour. Since 1971, 2 filters
(L1Bc and L37c) and most Nikon lenses have had NIC. The first new lens to be
given NIC is the NIKKOR-N 35/1.4. Other existing lenses were updated in the
course of time and these lenses had the suffix .C attached to the lens ID,
e.g. NIKKOR-H.C 50/2, NIKKOR-S.C 50/1.4, etc. However, if you look at the
lens with reflected light, you will note that not all lenses are completely
green in all the lens elements. Some have purple coatings inside. I suppose
this depends on the optical formula used. However, overall, NIKKOR lenses
have been consistently green coated since 1971.
Hope this has been helpful
Dr. Lim Kok-Hoo
Date: Thu, 19 Nov 1998
From: Dirk-Roger Schmitt Dirk-Roger.Schmitt@DLR.DE
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Coatings: T* vs HFT
>At 10:24 AM 1998-11-16 +0900, Jim Chow wrote: >>Does anyone know the technical/visual differences between the Zeiss T* and >>Rollei HFT coatings? > >Cutting through the sales hype as generated from both Oberkochen and >Braunschweig, there really ISN'T a difference. The mechanical part of the >process is identical (as is that used by Pentax and, probably, everyone >else, by now!), but each manufacturer selects the precise chemical bath used. > >I haven't noticed any difference in use between my T* coated Zeiss optics >and my Rollei HFT stuff. > >Marc
There is no chemical bath.
The coatings are evaporized by electron beam evaporation or target
sputtering under high vacuum.
Coating plant manufacturerers as Leybold or Balzers are selling the vacuum
machinery with the complete process. There is very very few development on
the coating by the lens makers. The residual colours you see in reflection
are choosed not by the performance of the lens but by marketing purposes.
Best example is that Zeiss eye glasses show a green yellow reflexion as
Rodenstock glasses show a blue red reflexion. In terms of the eye glasses
the colours are even different for the European or US market.
Greetings
Dirk
rec.photo.equipment.35mm
From: bob@bobshell.com
[1] Re: WOULD YOU LIKE TO SEE...
Date: Fri Dec 11 05:44:40 CST 1998
esquire-NOSPAM@.clear.net.nz wrote:
> I'll have to say that little unknown factory out in Taiwan (or was that > Thailand). great lens cap. they seem to make it for everyone.
It is a little-known fact that using cheap third-party lens caps is dangerous
to the health of your lenses. Plasticizer fumes from some of them will strip
the multicoating right off the front of your lens, greatly reducing the
contrast in your images. Stick with proper name-brand caps to be safe.
Bob
Date: Sun, 13 Dec 1998
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Re-coated lens
At 12:43 PM 1998-12-13 +0100, Jimi Axelsson wrote:
>I came across a camera (a Rolleicord ´38 (IIb if I know anything)) whose >lenses, according to the seller, has been re-coated. Now this seems pretty >strange to me, and I do not know who has made the re-coating of the lenses. >Do any of you know of any similar instance? Could for example F&H have done >this kind of work for an earlier owner?
Zeiss offered a coating service, as did Leitz, on uncoated lenses from
approximately 1950 until 1965. There are a number of coating facilities
today: anyone wishing to have an uncoated lens coated should contact,
inter multa alia, John Van Stelten focalpt@ecentral.com at Focal Point.
John charges per lens surface, though, so it can be expensive.
Marc
Date: Fri, 26 Feb 1999
One word of caution before going doen this path: If the foam pads between
the prism and the housing have adhered themselves to both surfaces,
lifting the housing off may pull the silvering off the prism.
Proceed with care!
Regards,
M.Phillips
Date: Sun, 04 Apr 1999
At 03:32 AM 4/4/99 -0400, you wrote:
I think the terms hard and soft coating are being used rather loosely
here. True soft coatings were chemical and not vacuum deposited. Kodak
used such coatings on some lenses in the late 1930's. The lenses for the
Ektra camera and the first Medalist were coated on _inside_ surfaces_
only. These coatings would rub off with ordinary cleaning so could be
applied only to protected surfaces.
Vacuum deposited coating may have originated at Zeiss in the mid thirties
but it was developed independantly elswhere and hard vacuum coatings were
applied to military optics in the US from about 1943. While there is
variation in the hardness of "hard" coatings none of them will come off a
lens without rather heroic effort. I think some of the older lenes which
show wear of the coating on the front surface must have been scrubbed over
and over in a way than most lens owners know better than to do.
Schneider evidently had some problem with coating when they first started
applying it after WW-2 but I've never seen a Schneider lens with a worn off
coating. I suspect the problems had more to do with controlling the
thickness, etc. I've seen plenty with scratched coatings, but that applies
to all coated lenses.
Scratching is mostly the result of cleaning lenses with dirty cloth or
paper wipers. I don't think you can scratch any vacuum deposited coating
with ordinary fairly carful cleaning with lens tissue and lens cleaner.
I have many Schneider lenses from the mid fifties and all are hard
coated. Zeiss may have had a patent on a particular method of vacuum
deposition, or on a particular material for depositing, but certainly many
other companies were doing vacuum coating in the mid fifties, the lenses of
the period are the evidence of this.
----
Date: Sat, 27 Mar 1999 12:45:43 -0800
From: Richard Knoppow
Re: the coating. WD-40 is oil in a solvent. It leaves a very think
coating of oil which can be pretty persistent. Try cleaning the lens with a
solvent to see if the problem is not just an oild coating on the surface.
Isopropyl alcohol from the drugstore works OK. The really soft coatings
were usually not used on outside lens surfaces.
It would be useful to know the dates over which Schneider, et al applied
the softer coatings. I have had several Schneider lenses, on and off
Rolleis, from the mid-fifties which all seem to have modern type coatings.
FWIW, Kodak used soft coatings on the inside surfaces of a few of its
lenses begining about 1940. All the lenses for the ill-stared Ektra camera
were coated as were the Eastman Ektar lenses which were re-named Kodak
Commercial Ektar after the war. Some other types may also have been coated.
----
Date: Wed, 07 Apr 1999
Bill,
It is sad that you're lens has separated. I have repaired several Rollei
lenses that have separated. If you search back in the archives you will
find that I have posted complete instructions on how to uncement and
recement lenses back together.
Todd
Date: Thu, 08 Apr 1999
I saw your article on lens recoating at :
http://www.smu.edu/~rmonagha/bronrecoatings.html. I resilver mirrors, but
this is not the type of service I offer. However, I get a fair amount of
questions about it. Can I place a link on my site (
www.mirrorresilvering.com) to your Lens Recoating page so as to better serve
my customers?
Remove spots, streaks and faded areas!
Date: Sat, 01 May 1999
Focal Point did a set of Mutars and a 2.8F for me. All of the lenses
were really moldy, mottled, speckled and otherwise unsightly. They came
back in amazingly good condition. Also, and I am hypersensitive to
this, the slotted rings were not marred by careless toolwork.
JC
Date: Tue, 11 May 1999
There are a lot of myths concerning the coating of lenses.
My opinion is, there are only few differences with the coatings.
Multicoating is a bit better than one layer coating, but that is marginal.
If lenses of today are different concerning flare that is due the lens
design, not due to differences of the coatings.
Nobody, neither Zeiss nor somebody else does coat lenses with a process
tailored to the specific lens design. If I achieve a reflectance reduction,
that will work for all lens designs.
The residual reflectance colours you see on the lenses of different
manufacturers are n o t due to a different performance. They are
adjusted for marketing reasons. Each optical manufacturer has its "own"
residual colours. The coating process is sold to the optical industry
together with the coating plant by the coating plant manufacturers as
Leybold or Balzers. Few own development is done by the optical industry on
standard coating processes. I have personnally seen a presentation of
Leybold company (one of the major coating plant manufacturers) where it was
explained that the the residual colours of coatings will we taylored to the
marketing goals of the customer.
Greetings
Dirk
Date: Sat, 01 May 1999
I have a gorgeous 2.8E Planar, but...there is separation in a ring all
around the edge of the taking lens (I assume this is occurring in the
two front elements, which seems to be fairly common). I've read about
the work of John Van Stelton of Focal Point in Colorado. Does anyone
have a general idea what Focal Point charges to have the elements
recemented? Can they make the lens as good as new? Thanks for your
help.
Greg Lawhon
Date: Sat, 01 May 1999
greg,
john charges 125 bucks per group. the planar will run you 250 to recement
and the xenotar 125. i got this quote from john a few weeks ago when i
inquired for myself.
andre
Greg Lawhon wrote:
From: Vasu Ramanujam v.ramanujam@worldnet.att.net
Just a little factoid regarding lens coatings: To get the slightly faded
effect in the war scenes in Saving Private Ryan, they are reported to have
actually stripped the coatings off of the movie camera lenses.
I have toyed with the idea of doing that to one of my old Minolta MC 58/1.4
lenses just to see what I'd get with an uncoated lens. Probably more flare
and probably something that can be used creatively in certain situations.
Anyone tried something like this? Know of a good lens coating remover?
Vasu Ramanujam
Rav wrote:
From: mtsano@aol.com (MtSano)
I just had two Leica lenses repolished and recoated by:::: Focal Point, Inc.
1017 So. Boulder Rd, Louisville, CO 80027. Pho. 303 665 6640. Cost will
be in
the $125-175 range, depending on the lens and its problems.
Check with them.
Gene.
From: "Kotsinadelis, Peter (Peter)" peterk@lucent.com
I second that. Focal Point did a Xenotar and a .7x Mutar for me and WOW!!!!
What a great job. On each the coating was the problem, light scratches whih
ch were not into the glass. John fixed both and they are better than new
(arguable to the purists, but IMHO the newer/modern coatings are always
better than the older.)
Peter K
From: John Stewart radiojohn@delphi.com
If you have a TLR with a badly desilvered mirror, please read this!! I
just had the opportunity to review (and take-apart) the new Polaroid
"PopShot" single-use camera. Normally, you return it in a postage-paid
bag for refilling and get $4.00.)
Inside is a mirror used to bounce the image from the lens to the film
pack. It is high quality and is shaped and sized VERY MUCH like the ones
found in Rolleis, Yashicamats, etc. Perhaps someone with a really bad
mirror will invest the $19.95 for the came ra to see if the mirror can be
used.
Please let us know. A review of the camera will be found (in a week or
so) at www.acpress.com in our newsletter's "Imaging" area.
Hope this "brightens the view" of some TLR users! ;) John
Date: Mon, 21 Jun 1999
At 08:24 21.06.99 -0400, you wrote:
Well again, the patent should be from the 1970's and already run out.
Everybody could use it now. But nowbody would do, because there are
nowadays much better and cheaper processes available. What protected is, is
the brand name T* or Rollei HFT.
Believe me or not, it is a cheap standard process nowadays you can order
everywhere for some bucks. And it is the same process eye glass
manufacturers are using. There is no more myth and no know-how in it anymore.
Do me understand correctly: The Zeiss as well as the Rollei lenses are
coated in a superior quality. But the quality is nowadays just state of the
art for every coating you can get. Buy a coating machine from Balzers and
they will sell you that process or even a much better one for some 1000 $.
The quality in such a process can be judged from the dust particles in the
coatings. The more less dust, the better the coating is. Take a small
Maglight and illuminate the lens from one site, look into the lens from the
other site. Compare the flare from the dust you see. You will be surprised
how this flare differs from lens to lens. Most reason for this scattering
is due to unproper dust particles in the coating layers.
The cheap process most companies are using is electron beam evaporating.
Best manufacturing companies for these process chambers are Balzers and
Leybold.
The most sofisticated coating process nowadays available is ion beam
sputtering. This process is available at Zeiss Oberkochen (however, Zeiss
did not invent it, they just bought it), but they do not use it for
consumer optics.
A mid range process is ion beam plating by Balzers. This is available at
Schneider and Biermann & Weber, but I don't know for what lenses they do
use it.
From: colyn.goodson@airmail.net (Colyn)
On Wed, 16 Jun 1999 02:03:15 GMT, joe-b@glopdircon.co.uk (Joe B.)
wrote:
If the glass surface (not the coating) is badly scratched or chiped,
you would want to consider buying a new lens, but if the coating only
is damaged or the lens has fungus or hazing, it can be easily
repaired..
If the lens has slight cleaning marks, they can be polished out and
the lens recoated.. it's only when these scratches are too deep for
the polishing to remove without removing too much of the glass surface
that you need to deside whether to let the repairman at extra cost
remove these scratches and then shin the element to make up for the
difference, but this is only a good idea if the lens is too valuable
to throw away..
Most cleaning marks are just slight damage to the coating and may or
may not affect the picture quality..
From: bc1959@my-deja.com
B Peters bill.peters@home.com wrote:
To do it right you will need to first make a test plate to do an
interference test against the existing scratched lens surface. Then
the lens element can be re-polished or re-ground and re-polished and
checked for accuracy against the test plate. If the scratches are deep
enough to require a significant amount of grinding to remove them, then
the center thickness reduction may noticeably lower the overall
correction of the objective, but removal of 0.2mm or less may not cause
much harm. Re-grinding may also cause decentration, which is usually a
more serious problem than thickness reduction. All of this can be done
successfully by a dedicated amateur optician with fairly simple
equipment, but you will need training, practice and patience. If
you're going to go to all this trouble, why not go all out and design
and make your own lenses - I have, and can say that it was definitely
worth the effort.
-Brian
From: "Frank Earl" fearl@utah.uswest.net
I have tried to get a pentaprism recoated locally. The people who do
antique mirrors were unable to get it recoated and in fact, took off the
rest of the coating. Unless you want historic restoration, I would suggest
that you find one of the older cheap Polaroid plastic cameras that has a
flat base. These have a front coated mirror that is relatively large and
can be cut down by you (or a glass shop) to match the size of the Ikoflex.
I have done this with a Minolta Autocord and it works just fine. The light
through the finder improved tremendously. If there is a difference in the
thickness of the mirrors (I would guess the Polaroid would be thinner as it
is newer) you can put brass shims under the mirror to retain proper
focusing. I have been buying the old Polaroids (the Kodak instant cameras
might also work) for about $2 at thrift shops. Good luck.
Subject: Re: Composition of lens antireflex multicoating ?
The basic chemicals used are various fluorides, and they are deposited by
direct sublimiation in a vacuum chamber. The antireflective properties
depend more on controlling the thickness of the layer than on the exact
chemical composition of the coating; the composition has more influence on
the coating's durability.
The reason that chemical cleaning is mostly not recommended is that many
common chemicals might react with the fluorides to discolor the coating
and/or impair its effectiveness. This is the reason for the warning against
cleaning lenses with the silicone-treated cloths made for polishing
eyeglasses: the silicone can react with the fluoride and impair its
effectiveness.
From: hrphoto@aol.com (HRphoto)
In order to have an effective anti reflection coating, the refractive
index of the coating material needs to correspond to the square root of
the refractive index of the glass. Since this changes with the various
wavelengths of light, multicoating with different materials usually
results in a more complete elimination of reflections off the glass
surface.
Heinz
From: abaddon@ibm.net (Michael Ross)
This caused me to think, and I dug up the following archive:
From: Jim Lebiedz jim.lebiedz@customcpu.com
I recently pickup up a very used lens for my Hasselblad. The Carl
Zeiss CF 5.6/250 T* lens had a terribly scratched front
lens element that afforded me the opportunity to buy it for very
little.
Thinking that it could not be too expensive to have the front lens
element replaced, I called Hasselblad USA and inquired
about the cost. Their reply was that they would only replace the
entire front lens group, which consists of 3 of the 4
elements that make up the lens, for $790, plus labor. To say the least
I was surprised by their response.
Not willing to pay close to $1,000 for labor, material and shipping I
sent an e:mail message to Carl Zeiss in Germany asking
them if I could just get the front lens element. Well, to my surprise,
in somewhat broken English, I received a reply. Carl
Zeiss replied that for 194 DM they would send me the front lens
element with T* coating. Translated into US dollars, that
was less than $100! Replying to them that I would like for them to
send it, two days later it was delivered to my door!
snip...
The poster then goes on to describe the successful installation of the
new front element...
Looks like it might be cheapest to purchase CZ optics in kit form!
Mike
From: "Michael Covington" mc@ai.uga.edu
....
I suggest you clean it carefully with lens cleaning fluid. I have
astronomical telescopes that get dew on them every time I use them; after
several years, the coatings are undamaged. A dirty coating will look
damaged.
--
From: h.nareid@nareid.demon.co.uk (Helge Nareid)
dickburk@ix.netcom.com (Richard Knoppow)
wrote:
This is nearly always true, even though _modern_ coatings can be very
scratch resistant. In particular, the coatings on the outer (exposed)
elements of a modern multicoated lens are nearly always designed with
scratch-resistance in mind. The term multi-coating covers a wide range of
coating types, and they are normally matched very closely to the
application. On the other side of scratch resistance - I had occasion to
discuss customised coatings with a coating specialist last week, and he
mentioned coating types which would be severely damaged by contact even
with water condensation.
We tend to use methanol. It is slightly less effective than acetone, but
it is much safer in use, and is much less to likely to inadvertently
remove an expensive coating. Pure ethanol is nearly as effective - in the
region I come from in Norway, moonshining is a fine (albeit illegal)
tradition, and a friend of mine used to make moonshine of a quality
suitable for lens cleaning (which is highly uncommon, by the way) ...
--
Date: Sun, 02 Jan 2000
Jim Brick wrote:
>Coatings on "early" coated lenses were soft. For Leica lenses, this was
>anything prior to the 1960's. I suspect Zeiss lenses are similar.
No. Zeiss developed vacuum-deposited coatings in 1935 and patented them
in 1939; hence, Leitz had to use drip coatings, which resulted in more
residual moistness and a softer coating until the Zeiss patent expired in
1959.
So, Zeiss had hard coatings for twenty years before Leitz did.
Marc
From Rollei Mailing List:
Godfrey DiGiorgi wrote:
Zeiss began regularly multi-coating lenses early in '72 and, by the end of
'73, were multi-coating virtually all production. They trumpeted the
process by marking lenses with the "T*" marking. We are now figuring out
that what Zeiss did was to license the "T*" mark for cash -- in other
words, manufacturers such as Rolleiflex or Hasselblad seem to have
received nothing BUT multi-coated lenses, as that was all that Zeiss was
making, but could only use the "T*" mark if they paid the freight.
Rollei did not; Hasselblad did, after a while. Still, we are finding that
all late F Rolleiflex production is multi-coated, though we cannot yet
ascribe a precise date to when "late" begins. 1975? 1974? 1976?
Marc
[Ed. note: Mr. Knoppow is a noted lens repair expert etc.]
you wrote:
The tarnishing observed by H. Dennis Taylor was not the white haze seen
inside lenses. Rather it is an oil-slick looking effect. It is most often
seen on the front surface of a lens, the inside being protected by being
inside the camera. This tarnish is clear, the haze is not. The haze is
most often observed inside sealed air-spaced cells. It may be due to
outgassing of anti-halation paint, or it may be some degeneration of the
glass. It may be that the cell is not really sealed enough to keep
polutants out over a very long time.
I've observed this effect on lenses made as recently as the late 1950's
or early sixties. It is found on coated lenses, which makes me doubt its
due to oxidation of glass. The coating might itself oxidize but the haze
seems to be very much the same on coated and un-coated surfaces.
Whatever the source, it seems to come off easily. It is well worth
cleaning lenses with it since it very materially degrades the contrast,
much more so than being simply un-coated.
Most lenses are not too hard to get apart and the haze comes off with
ordinary lens cleaner. Inspecting by shining a flashlight through the
lens will show up this haze as well as many other defects and blemishes.
Carry a pencil flashlight and a low power loupe with you when shopping for
lenses.
H.Dennis Taylor was the inventor of the triplet. He worked at the time
for Cooke and Sons, an manufacturer optical instruments. Cooke did not
want to manufacture photographic lenses so allowed Taylor to offer the
design to Taylor, Taylor, and Hobson. TTH made the lens but called it a
Cooke Triplet after Taylor's employer. H.D.Taylor later worked for TTH and
made the discovery there that tarnished lenses had higher transmission
than freshly polished ones. He understood the reason for this and tried to
find a way to produce artifical tarnishing. He was unable to find a
practical method. Currently, two methods are used for coating. The most
common one for photographic objectives is vacuum deposition. The second
method, often used for plastics is bathing the lens in a solution which
deposits the coating. I do not know of a single source with details of
coating methods although there is stuff scattered throughout the
literature.
Those familiar with radio frequency transmission will find that
transmission theory and filter theory are analogues of optical thin film
coatings. A single anti-reflection coating is analagous to a quarter-wave
matching section.
----
From Rollei Mailing List:
you wrote:
The color of the coating will tell you which colors it _doesn't_ work
for.
Single coatings work completely at only one wavelength. That wavelength
is usually placed somehere near the center of the range of visible or
photographable light. When its in the green the coating will have a
magenta (violet) color. When shifted toward the blue end, the coating will
have an amber color. Sometimes coatings of differing thickness, and
therefore optimum wavelength, will be used on the various surfaces of the
lens to try to broaden out the band of effectiveness of the coating. When
that is done the color of the reflections from different surfaces will be
different in color.
Multiple coating is a way of broadening out the bandwidth over which the
coating is effective. A multi-coating may be no more effective at the
single color of a single coating but will have nearly that efficiency over
a wide range of colors.
A perfect multi-coating would have no characteristic color. In fact, if
it were completely effective, the coated surfaces would have no reflection
whatever. In practice, there is some residual color, which may vary with
the angle of incidence of the light, and will vary with the design of the
coating. Mostly, it will be at the extreme ends of the spectrum.
Multicoated lenses often have red reflections.
While the effectiveness of a single coating falls off slowly with
wavelength on both sides of its optimum, a multiple coating may stop very
abruptly at its limits.
----
[Ed. note: ferric chloride is a caustic chemical, so this info is just for
information purposes on past practices, as noted, commercial firms will do
this for you prior to recoating mirrors...]
Dan,
As I recall, these coating companies will strip the old coating for
a small fee of maybe $10, or you can do it yourself using Ferric Chloride.
This is sold by Radio Shack for stripping circuit boards. With a small
mirror such as yours, you can place a piece of parchment paper over the
mirror and apply the Ferric Chloride with a dropper to the paper. It won't
take very much to soak the paper. Do this in a a plastic tub. Several
hours
or over night should strip it. You can rinse it down the sink followed
by lots of running water.
CAUTION: WEAR SAFETY GLASSES and rubber gloves also. This
material is corrosive. It will also corrode stainless steel sinks
(hence the need for the plastic tub). Better yet, have the coating
company do the stripping. But if you do it yourself, PLEASE BE
CAREFUL.
Alan
Dan Bush wrote:
I intend to have the mirror of my (1970) 8" Dynascope recoated. DO
From Rollei Mailing List;
Focal Point removes your lenses, de-cements the elements, polishes and
re-coats them, then cements them back together. Once this is done they
have to go back into the camera :-)
Here comes the calibration matter. In order to see a shapr picture on the
ground glass and have a sharp one on the film at the same time, the two
lenses must be calibrated precisely. There are some fancy pieces of
equipment used by professionals and I am sure Focal Point has some as
well.
The information below is just hearsay as it has not happened to me, but I
remember reading a few posts (two or three of them and they were likely
from different posters, though I cannot remember precisely) saying that
after having the lenses worked on by focal Point, the calibration was off
and the pictures were not sharp on tthe film. Make of this what you want,
but I am still sending a Tele to Focal Point this year :-)
-_______________
From Rollei Mailing List:
you wrote:
Perhaps van Stelten has data showing what his coatings do.
Single coatings have minimum reflection at one wavelength and fall off
on either side of that. Since the total bandwidth of the light for visual
and ordinary photographic processes is only about an octave a single
coating can substantially reduce the reflection over the whole range. The
thickness of the coating is chosen to adjust the null at some point near
the center of the spectrum but the exact point is a matter of choice for
the lens designer. The color of the coating by reflected light will be the
compliment of the color of the null. Typical coatings are set to null in
the green so will have a magenta or purple color. When they are set to
peak more toward the blue the reflection will be more yellow.
Coatings work best only for light striking the surface at 90deg. For
light striking at an angle the effectiveness is less.
Multiple coatings are like complex eletronic filters. They are intended
to broaden the spectrum over which the coating as a whole works. An ideal
coating would have no residual reflection at all.
Some single coated lenses have somewhat different coating thicknesses on
the various elements so the color of reflections from internal elements
may not be the same as from the front. This is another way of attempting
to broaden out the effectiveness of the coating.
A Xenotar or Planar has eight glass-air surfaces. This is about where
coatings start to make a really significant difference in contrast. For a
Tessar or Triplet, with six surfaces, the difference is less. For
instance, I have both an un-coated and single coated Kodak Ektar, 127mm,
f/4.7. Both lenses have been thoroughly cleaned of haze and dirt. It is
very difficult to see any difference in side by side comparisons.
Lenses with more surfaces than a Planar will likely be unsatisfactory
without effective coating.
Even a single coating usually requires at least three coating steps.
Typically a substrate is coated first, then the anti-reflection coating,
and, often, a protective coating on top of that.
Multiple coatings may run to a dozen or more layers.
Modern coatings are applied by vacuum deposition, the most recent
version is electron deposition. I have no idea of what van Stelten uses.
I had some brief experience with vacuum deposition many years ago in the
manufacture of precision metal film resistors for space vehicals. There
remains a good portion of black art it it:-)
----
From Hasselblad Mailing List:
I worked for a number of years at Varian Ion Implant Systems, one of the
makers of the 'ion bombardment' equipment Henry spoke of. It can indeed be
used to coat filters with appropriate specie, as long as the element you
want to use can be coupled to another to form a gas a room temperature.
Although designed for the semiconductor industry, one of my jobs was to
track where old ion implanters ended up. Some are used in medical industry
to harden artificial joint materials, for instance. I think a competent
coating engineer could work with one of several companies using old ion
implanters to come up with a reasonable 'recipe' for coating glass. This
is same business model as 'fabless' chip companies, just rent a fab for a
week
or so.
[Ed note: Mr. Small is a noted expert on Zeiss and related optics
etc.]
Austin Franklin wrote:
It obviously IS coated. All Zeiss lenses made for Hasselblad were, to my
fairly extensive knowledge, coated. (There may be a rare technical lens
which wasn't, but Rick Nordin would be the guru to consult on this point!)
This lens certainly is coated. Zeiss began regular production of coated
lenses in 1937, and, together with Asahi, introduced multi-coating in
1973.
Marc
msmall@roanoke.infi.net
From Hasselblad Mailing List:
Yes of course the Biogon is coated. Not the "rainbw style" but yet. Even
the new 903 looks the same way. I have heared (and possibly it is true)
that the hand-calculated, more than fifty years old lens when recalculated
by a computor could not be improved in any way. So the lens is basically
the same as the first one. But the barrel is somewhat changed......
Ulf Sjögren
Sweden
From hasselblad Mailing List;
ULF SJÖGREN wrote:
Yes of course the Biogon is coated. Not the "rainbw style" but
yet. Even
the new 903 looks the same way. I have heared (and possibly it is true)
that the hand-calculated, more than fifty years old lens when recalculated
by a computor could not be improved in any way. So the lens is basically
the same as the first one. But the barrel is somewhat changed......
I suspect it is more appropriate to list the Biogon as being designed with
"computer assistance". Its designer, Bertele, was one of the first major
designers to use computers and his employer, Wild, was the second optical
firm, after Leitz, to buy a computer for lens design. I believe Zeiss and
JSK were the next two.
Marc
msmall@roanoke.infi.net
[Ed. note: reminder that some astro folks may be able to help...]
SHAMELESS COMMERCIAL PLUG:
I am offering a mirror refiguring service. Check out my web site:
http://tlepage.home.mindspring.com/refigure.html
I will work for eyepieces! :-).
Scott
From: "Malcolm Stewart" malcolm_stewart@megalith.freeserve.co.uk
Hope this is brief enough(!)
Lens coatings vary from company to company, but in the simplest case where
there's just one layer, it has to be one-quarter wavelength thick for the
light for which you're trying to remove the reflections. There is another
requirement which has to be met, and the refractive index (r.i.) of the
coating should be the geometric mean of the external medium (air) r.i. and
the underlying glass r.i. In practice this means the square root of the
glass r.i. (Early coatings were of this type with, sometimes, different
colours on different surfaces in the lens - this helped to balance out the
colour transmission.)
These two requirements taken together are one reason why multi-coating is
done, in that the extra layers allow better results over a wider
wavelength range. Coatings are applied in ultra clean conditions in a
vacuum, and the coating material is vaporised - again, different companies
have different techniques for heating the coating material. Camera lens
coatings are relatively simple compared with some done for the mirrors
used in laser systems where very many layers may be used in an attempt to
achieve almost 100% transmission or reflectance - at a single wavelength.
Different techniques are used for gauging when enough coating has been
deposited. (Without coating, the reflection from a surface increases as
the refractive index increases- window glass typically reflects about 5%
of the incident light.) Magnesium fluoride is one of the coating materials
used some years ago - the details of materials used today are kept
confidential for commercial reasons.
At high angles of incidence the path length through the coating layer may
not meet the quarter wavelength criterion, and the coating may become less
effective.
M Stewart
Joseph Tainter jtainter@mindspring.com wrote
From Rollei Mailing List:
FWIW: "...the efficiency of aluminum over the entire spectral range
is higher than that of any other metal. It is but slightly less efficient
in the visible spectrum than a fresh silver coat, with a reflective
index of about 88 per cent, but it retains this reflective quality
almost indefinitely. Its absorption in the ultraviolet is considerably
less than that of silver, and so it is decidedly superior for
photographic purposes." (Allyn J. Thompson, 1947, "Making Your
Own Telescope," Sky Publishing Corp., p.20)
The use of aluminum on telescope mirrors is essentially universal
these days.
--
From Rollei Mailing List;
you wrote:
What is happening is probably due to the protective coating over the
Silver. Silver coatings oxidize very rapidly so are coated with a lacquer
to protect them. As long as the lacquer is intact the mirror stays bright.
Once the lacquer starts to break down the silver underneath oxidizes very
quickly and the rest of the lacquer is likely to peel off too. Second
surface mirrors are protected by a fairly thick coating of opaque paint
over the silver on the back so tend to last longer than first surface
mirrors. The front protective lacquer can also become yellow.
Aluminum coatings are nearly as bright as silver and have much longer
lifetimes. The aluminum surface forms a one-molecule deep layer of
Aluminum oxide on the surface almost immediately on exposure to the air.
Aluminum oxide is very tough and does not further oxidize. This layer has
little effect on reflectance.
The efficiency of mirrors can be increased by coatings similar to lens
coatings, but adjusted to maximize reflection rather than to minimize it.
Dim Rollei finders may be due to old mirrors which are in poor condition
but an Aluminized mirror won't produce a dim image. The dimness is more
likely to be due to the nature of the ground glass (although Rollei stock
GG is quite fine grained) or a bright surround, or the fact that we have
gotten used to 35mm SLRs with collimated finders (makes the corners
bright) and lenses which are one or two stops faster then the Rollei
finder lens.
----
From Rollei Mailing List:
Sorry for chimming in late, but was out camping, putting my Rollei through
alot of abuse.
Other than keeping Rollei's as collectors and not users, modern enhanced
aluminum coatings for telescope mirrors can get up to 95% reflectivity.
A 5% loss is not much, compared to the amount lost through the ground
glass.
Typically, the "enhanced" coating is an additional layer of magnesium
flouride and a layer of cerium dioxide to the base aluminum coating. As
most reflecting telescopes use multiple mirrors, the light losses add up
quickly.
Is it noticible? Yes, especially when I compare my home built telescope
side by side to a store bought telescope, most, due to cost are made with
regular aluminum coatings (about 85% reflectivity).
However, before you send off your Rollei mirror, you might want to check
with your the company doing you coating, as to whether or not they
can/want to take off your silver coating before they re-coat the mirror.
Hope this helps,
Vincent.
...
[Ed. note: Mr. Erwin Putts is a noted author of photobooks (e.g. on Leica
Cameras and lenses) and lens testing authority, photoindustry
historian...]
The information on which most of Lug discussions is based, is extracted
from product brochures, company leaflets, articles in the popular
photographic press, personal experiences and the many books about Leica
and photography, which in a large part are based on product brochures
etc.Generally this information is not the best source for the advancement
of knowledge.
In a report from the Naval Research Laboratory from October 3, 1946, a
number of scientists report on the state of the coating technique in the
Zeiss and Leitz factories in wartime. They note specifically that both
companies use multiple layer coating as a technique, but because of its
costly procedure, only experimentally. It can thus be established that the
technique multilayer coating did exist at Zeiss and Leitz.
In a report of the BJP from Otober 24, 1975, also referenced in The Leica
Collectors Checklist, it is stated that Leitz used multiple layer coating
in the Summilux 1.4/35 (British Patent Literature from 1957). Reports in
the Journal of Optical Society of America in 1957 discuss the use of
multilayer coating based on progress in the leading optical firms.
ML-coating has been used since the fifties in many optical instruments,
but mass production was not yet possible. The innovation of OCLI and
Pentax is NOT to invent the ML-coating, but respectively to design a
technique for muli layer depositing in an economical way and to make a
marketing hype out of its application on Takumar lenses. Other firms
already used it, but did not advertise it.
The Summicron-C 2/40 coating. In Gunter Osterloh's handbook on Leica M it
is stated that Leitz policy dictates that no information is given about
the type of coating of lenses. Leitz position is simply that coating is
part of the optical design and single and multiple layer coatings are
applied as deemed necessary and no specific references are to be made. And
even today Leica is not promoting the fact of ML-coating although all
their lenses now employ MLC.
So given this directive it is logical that Kisselbach (Leica employee)
simply notes that the S-C is coated. And in the same vein magazines like
PP and MP will report what they know: the lens is coated. They are right
in not speculating about the use or absence of MLC as you cannot know
without given specific facts from the company and as the company says they
will not disclose the info, that is as far as they can go.
Given Osterloh's position his statement reflects the status-quo about the
S-C: without direct access to the company info (which is not disclosed or
at least may not be publicized) we cannot infer from the designation that
the S-C is coated , that is it therefore not multi-coated. This would be a
fatal flaw in any logical reasoning.
Erwin
From Rollei Mailing List:
you wrote:
Previous thread snipped...
The problem with repolishing is when an attempt to remove a deep scratch
is made. Even if the radius of curvature is preserved the thickness of the
element will be changed. The sensitivity of this varies among lens designs
but it certainly is a last resort.
Probably a scratched coating can be gotten off without changing the
figure. The coating itself does not change the figure.
Recementing varies in difficulty. When the parts to be cemented are of
equal diameter they will be automatically centered when they are edge
clamped, assuming they were centered correctely to start with.
Centering is done by fastening the lens on a rotating tube and examining
the reflection of a point source with a telescope. the lens is rotated
while being slid around on the tube. When the two reflections are
absolutely stationary during rotation the lens is clamped with another
tube on the other side and the edge ground. The edge must be exactly
concentric and coaxial with the optical axis.
There are some lenses where two or more elements of different diameters
are to be cemented. The Schneider Angulon is an example. To center these
correctly a precision fixture is required.
The difficulty and hazard of getting elements apart depends on what they
were cemented with. Pre 1945 lenses are almost uniformly cemented with
Canada Balsam. This will part in hot water or by heating the lens gently
on a hot-plate. Later lenses, and some Aerial lenses made as early as
1941, are cemented with various types of synthetic cement. These require
rather high temperatures to get apart. Summers Optical has a de-cementing
fluid which is used at something like 350F. It is relatively safe,
however, there is always the danger of cracking from thermal shock or
differential expansion of the glass parts.
Summers also has a selection of optical cements which are not hard to
use. The one I use is the standard two-part cement which requires curing
at 150F. This allows lots of time to fix mistakes since the mixed cement
stays usable for several hours.
They also make quick curing cement which works at room temperature and a
couple of types of UV curing cement.
I have had success in re-cementing a number of fairly simple lenses and
also a Wollensak copy of a Protar with three cemented surfaces on each
side. That was a bit of a chore.
I've also used Canada Balsam, but its actually harder to use than the
synthetic stuff. It also must be heat cured and must be of the right
consistency to begin with. The synthetic cementis superior in every way.
Unfortunately, both the cement and the de-cementing solvent must be
shipped as hazardous materials, just about doubling their cost.
----
From Rollei Mailing List;
....
How many of each have you seen?
Seriously, it could be a difference in the coatings since it is usually
the coating that is scratched. Optical glass also varies in hardness. The
two lenses are similar but of different designs and the front elements are
likely of different glass.
Lenses are harder so scratch than people think. If you are reasonably
careful you will never scratch one.
I used to see press guys cleaning lenses with the back of a tie. Silk
may be OK (if they were silk) but a dirty tie thats been around is not OK.
I see a lot of lenses at the camra sales which seem to have been cleaned
with sandpaper.
----
From Rollei Mailing List:
The recoat and polish was performed by John Van Stelten
(focalpt@ecentral.com) and cost somewhere in the neighborhood of $200.
Jonathan
----- Original Message -----
From Rollei Mailing List:
John Van Stelten charges 250 bucks for repolish/recoat and
125 dollars per cemented surface should the lens need re-cementing. For
example, a Xenotar will cost 125 bucks while the Planar would cost 250 to
redo because the front element in the Planar is a cemented doublet.
Andrei D. Calciu (VA-4270)
From Rollei Mailing List;
Well, repolish/recoating can be done without affecting the lens formula
(i.e., radius, curvature, etc). The actual activity involved means the
coating is buffed off the lens affter heating the lens at about 200
degrees.
If a lens defect is big enough to be felt when you run a fingernail over
it, than it is non-repairable (at least non repairable without turning
your Planar into a Trashar).
There are many risks involved with this repolish job. The heating can lead
to de-cementing, or worse, to a heat-induced fracture in the lens. The
recoating does not affect the lens formula if done properly. The amount of
coating deposited on the lens is negligeable and will not change the lens
formula.
De-cementing can really make Coke-bottoms out of a good lens. Once
de-cemented, the lens must be centered and the amount of glue must be
minimal and properly cured in order to avoid destroying the work of the
Lens Gods. An optical bench is mandatory for this operation. Doing it at
home, on the kitchen table is definitely a no-no.
Andrei D. Calciu (VA-4270)
[Ed. note: caveat emptor! but you might find this book reference useful,
so...]
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There are several techniques discussed: Preparation of new Front Surface
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Restoration section should be of interest to the collector, since it
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Front Surface Mirrors are ideal for use in a wide variety of optical
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specialized tools or materials. Preparation takes very little time or
effort.
In addition to making and restoring Front Surface Mirrors, there is a new
section devoted to precision cleaning of optical surfaces such as
un-mounted filters, fresnel glass and existing front surface mirrors.
These cleaning techniques are used in laboratories to clean optical and
laser systems where the demand for absolute cleanliness is mandatory.
The Guide is $9.00 + $1.50 Postage. It is Laser Printed in black and
white, 8-1/2 x 11, and Velo Bound.. Shipped First Class. Order From: H.C.
Maxey, P.O. Box 16289, Salt Lake City, Utah 84116-0289.
If you have any question, please feel free to write or send me an e-mail
message. I will be glad to do whatever I can. I offer e-mail support
after your purchase should you have any problems. The processes are very
simple, so I doubt you will have too much difficulty.
HCM
From Minolta Mailing List:
It's sort of a Leica mystique. While Leica produced the first multicoated
camera lens their coating was a little on the soft side and was very
delicate and easy to scratch. Zeiss and Pentax were doing some
collaboration during that time and Pentax bought the rights to a new
coating deposit process developed by an American company called,
appropriately, Optical Coatings. From this they developed their patented
hard coated 7 layer SMC coatings (also called by another copyrighted name
as Ghostless coatings). Some or all of their competitors licensed the
rights to either part or all of the patents involved. I've got a list
somewhere on which companies and how much they bought. Leica held out as
they figured they would get it right sooner or later. Zeiss got the rights
due to the cross licensing they were doing at that time. However after the
famous Honeywell-Minolta suit all the camera makers got together and
decided to cross license each others patents regardless of whether they
used them or not.
Doing a patent search will produce interesting things. Such as Pentax
actually developed and owns the original patents used by Canon to develop
both eye-controlled focus and image stabilization even though Pentax has
never used either outside the lab. Pentax makes a bunch of its money from
licensing fees of its technology. But it is still the only family owned
Japanese maker and they don't have the capacity to do a lot of innovative
things all the time. You will notice that both Contax and Pentax announced
new 35mm/full frame digital cameras at the last show both using the full
size Philips 6 MP CCD and their standard 35mm lenses. The impact of this
is that you won't see the current Nikon D1, Canon D30, and Fuji FinePix
2/3 CCD digital cameras in a year or two. They will be replaced with
cameras based on the new chip real fast. I've noticed quite a few Nikon
D1 users selling longer lenses on eBay and being forced to replace their
300/2.8 with a 200/2.8 to get the same image scale. They don't like doing
that. While a 2/3 CCD 4.3 MP camera sounds great the amount of increased
information on a 6 MP with standard 35mm image scale will make it lots
easier to use. As it is you have to relearn a lot of stuff.
Basically a Pentax SMC FA* and a Zeiss T* lens have the best
anti-reflection coating (internal reflection around a strong light source
causes flare). But it is still a lens by lens problem not really a lens
maker problem. Some are just better than others by both optical design and
coating efficiency.
Lenses with good coatings and fewer elements are generally better.
Sorry to ramble on.
Kent Gittings
...
From Rollei Mailing List:
Javier Perez wrote:
No. Early coatings were quite soft, in fact, especially those who did not
share in the Kodak/Zeiss vacuum-coating patents. The purpose of lens
coatings is the reduce flare.
Marc
msmall@roanoke.infi.net
From Rollei Mailing List:
....
During WW 2, coated optics were considered so valuable that repair shops
aboard capital ships were equipped with vacuum devises to recoat optical
equipment in which the soft coatings of the day wiped or weathered off.
I was told this by a repairman who had served aboard a carrier as
precision equipment maintenance mechanic. He said almost all carriers and
battleships had such capabilities, even many cruisers.
Allen Zak
From Rollei Mailing LIst;
ShadCat11@aol.com wrote:
This is absolutely true, in the US and UK Navies, at least. Zeiss
coatings were a bit harder but, even so, Kriegsmarine repair facilities at
every major German naval base performed the same role.
Marc
msmall@roanoke.infi.net
From Rollei Mailing List;
you wrote:
No, these are hard vacuum coatings, probably made of Magnesium flouride,
which is fairly hard. I am not sure what "extremely careful" means, I
would be careful of any lens. Some optical glass is pretty soft and
coatings are softer than some glass. Cleaning should be done with the
object of keeping grit of any sort from getting trapped and rubbed against
the glass. Tissue used for cleaning should be used once and discarded. I
don't like the use of lens brushes, which an pick up grit and scratch the
next time they are used, a one-time brush can be made of lens tissue by
rolling into a tube, tearing the end and folding the torn ends so they
face the same way. Use this once and toss it.
Some lenses I've seen look like they were scrubbed with a pad of steel
wool.
----
From Rollei Mailing LIst;
Aren't you actually polishing off the coating which is the first thing to
get scratched?
I had a bad Xenotar on a 2.8E but had it redone by John Van Stelton. Yes,
it was a bit more pricey, but the scrtaches were in the coating so
stripping
the coating, polishing and then recoating the lens yielded a perfect
Xenotar
(although the user body leaves a bit to be desired).
PK
From Rollei Mailing List;
Actually, the lens coating serves several purposes:
1.- reduces reflections
all these effects plus much more can be achieved with filters. Of course,
Schneider, Zeiss and others will tell you that you should avoid certain
filters (i.e. skylight) because their effect is negated by the
multicoating techniques used in recent years. Besides, ANY filter placed
on a lens will alter the focal length (by 1/3 of its thickness), and may
also introduce a certain degree of other aberrations (that have been
compensated in the original lens design).
-_______________
From Rollei Mailing List:
you wrote:
Quite true. The Planar and similar lenses have eight glass air surfaces.
This is about the maximum that can be tolerated in an uncoated system
(although there were certainly lenses made with more). When Zeiss needed a
fast lens for the Contax Bertele used his Ernostar lens as the basis for
the Sonnar which has only six glass air surfaces but four cemented ones.
Bertele liked the design but also was trying to minimize flare in a lens
which needed to be complex because of its speed (f/1.5) and the high
degree
of correction desired. The Contax Sonnar was an excellent lens. The
version
of it made by Nikon for their rangefinder cameras made their reputation.
However, Zeiss and others (E.Leitz among them) used the Planar-Biotar type
for most other f/2 or faster lenses.
Taylor noted that tarnished lenses had higher transmission than freshly
polished ones. He understood the principle by which the tarnish was
working and tried to find a way of duplicating it in a controlled way. The
use of acid was not to etch but, rather, to tarnish, or oxidize a thin
surface layer on the glass. Taylor's method was not sufficiently
successful for practical use. There was a great deal of research into how
to produce practical lens coatings. Zeiss came up with the vacuum
deposition method about 1935 but it was not adopted for general use until
after 1945. Kodak used chemical coating methods starting about 1938, but
the resulting coatings, while effective, were very soft and could be
removed by ordinary cleaning. They were nonetheless used in premium lenses
but only on protected internal surfaces. The lenses for the ill stared
Ektra camera, and the Eastman Ektar, forunner of the Commercial Ektar,
were coated in this way. I believe the lenses for early Medalist cameras
may also have been coated.
There were many other researchers. RCA, for instance, reported on the
use of chemical coating sometime in the mid to late 1930's. I am not sure
of the application but think it may have been for the microscope
objectives used for photographic sound recording. The coatings were too
delicate for practical use.
Vacuum coating started to be widely used around 1946 but it was several
years before the majority of lenses were coated. The process requires some
expensive equipment and special knowledge. Goerz-American, for instance,
seems to have been a latecomer to coating, perhaps because of having to
farm it out.
The back pages of popular photography magazines of the immediate post
war era have adds from companies offering to coat existing lenses. I
expect they ruined a few in the process.
I have, BTW, a pair of Bausch & Lomb U.S.Navy night binoculars, which
are coated but bear a manufacturing date of 1943. I think these were
coated after manufacture. Many binoculars of the period bear labels
warning that they are coated and need to be treated with care. I would be
beholden to anyone with definite knowledge about this.
Don't ask why I am up at this crazy hour typing into the computer (which
is awake and scheming all the time), its time to go back to sleep.
----
From Rollei Mailing List:
you wrote:
No, these are hard vacuum coatings, probably made of Magnesium flouride,
which is fairly hard. I am not sure what "extremely careful" means, I
would be careful of any lens. Some optical glass is pretty soft and
coatings are softer than some glass. Cleaning should be done with the
object of keeping grit of any sort from getting trapped and rubbed against
the glass. Tissue used for cleaning should be used once and discarded. I
don't like the use of lens brushes, which an pick up grit and scratch the
next time they are used, a one-time brush can be made of lens tissue by
rolling into a tube, tearing the end and folding the torn ends so they
face the same way. Use this once and toss it.
Some lenses I've seen look like they were scrubbed with a pad of steel
wool.
----
Date: Sat, 13 Jan 2001
In many cases recoating will cost more than $200.00. You can try
International Camera in Chicago....IF they are still around. The last
lens I sent to them cost $300.00 to recoat.
Mike
"mkuszek" mkuszek@mediaone.net wrote
From Rollei Mailing List;
Here is a source for aluminum coating of mirrors. Ran across him on a
telescope article. He does do mirrors for TLRs and other small jobs.
"Bob Fies" alcoat@sirius.com
--bob.
From Contax Mailing List:
All multicoating isn' t the same. There should be no difference in lens
coating between identical Hasselblad and Fuji lenses. Maybe they changed
the coating at some point in production and one lens is older than the
other.
Zeiss T* is not just one thing. Coatings are matched to lens formula and
type of optical glass.
...
Bob
..
From Rollei Mailing List:
Bob Shell wrote:
Well, both Zeiss and Rollei (and a slew of others) use the Zeiss/Asahi
PROCESS for multi-coating, but each manufacturer produces its unique mix
of chemistry; with the better manufacturers, they fine-tune the mix for
each lens type.
Marc
msmall@roanoke.infi.net
From Rollei Mailing List:
Ajit,
Try E-mailing this guy.
alcoat@sirius.com
He aluminizes mirrors for telescope makers. I talked to him once about
re - doing some mirrors for me, and I think it was pretty reasonable if
you sent him more than one at a time, and if you removed the old
aluminum yourself. That's easy with bon ami. He has a website
www.sirius.com
Gene
From Rollei Mailing List:
Silver vs. alumin(i)um mirrors :
For a good summary about what the industry can offer now, you can
check this web site (a European company specialised in mirror
coatings) http://www.gclinc.com/techinfo.htm
As a summary up to 97% can be achieved with protected silver in a
broad visible wavelength range, whereas a special coating on
alumin(i)um allows to reach 94% but in a more limited wavelength
range.
--
From Rollei Mailing List;
I checked with Edmund Scientific and they have mirrors (51 x 51 mm) with
aluminium coating that will fit the pre-war 4x4 Rolleiflexes if they are
cut, and they cost only $4.25 !!!! I will order three of them!
I first thought about cutting my new Rollei mirror to fit, but it cost me
$60, so I better save it...
/Patric
From Rollei Mailing List;
My thanks to all those who responded to my queries on Rollei mirrors and
to those who went out of their way to help me out by dipping in to their
cache of spare parts! The camaraderie in this newsgroup never ceases to
amaze me!
I did find out a few things which I feel the group may find useful, and
thought I'd share it with you.
After much looking around, I spoke to five probable companies, of which
two look like paydirt. Both of them had done recoating of TLR mirrors
before and both recommended Aluminum coatings.
The first is ( Thanks to Harry Fleenor for this one ):
This is a family run business which dates back to 1927 and the lady who
runs the shop is Patricia Clausing. She recommended the 'Beral' coating
developed by them as the optimum, with 91% reflectivity .Being harder than
Aluminum coating, it facilitates washing or cleaning. She said she would
do both my Rolleiflex mirrors for $40.00 plus $5.00 shipping. See details
of the various coatings at their website. They will strip the original
coating and recoat the mirrors.
The second was Bob Fies at:
I spoke to him and he sounded like a wonderful gentleman. He recommended
Aluminum coating and said that he had recently done a TLR mirror. He
stressed that Aluminum coatings are soft and will not tolerate much
handling. He quoted me $40 for the first mirror and an additional $7 for
the second, plus shipping.
I hope to send out my mirrors in the next couple of weeks. I will report
on how they turn out.
My thanks once again to all those who tried to help!
Ajit
From ROllei Mailing List:
you wrote:
Recementing lenses is quite practical but its cost depends a lot on the
amount of labor necessary to disassemble the lens. Where the cemented
elements can be removed easily the job is not too difficult.
Your address indicates you are in the Netherlands, I don't know of
anyone there who does re-cementing but others on this list might. Its even
possible that Zeiss might do it. This lens should have been cemented with
a synthetic cement which should not fail, although I've seen other Zeiss
lenes with separating elements.
You can even do it yourself although the cement and the solvent for
decementing must be shipped as hazardous materials, at least in the US.
That about doubles the cost here.
To get an idea of how lenses are cemented see Steve Grimes web page at:
http://www.skgrimes.com
The cement is available from Summers Optical at:
http://www.emsdiasum.com/
Click on Summers Optical. There is an on-line primer on lens cementing.
Its really not very difficult.
----
From Leica Mailing List;
douglas@dysmedia.com writes:
Douglas, I am not an expert, and I have no hard facts, but.... I have a
DR Summicron that I bought cheap that had cleaning marks and or scratches
on the front element. I sent it to John VanStelton at the Focal Point to
be polished and recoated. Before he worked on it the lens was virtually
unusable because of flare. When I got it back it looked like new and
performs wonderfully. The difference is nothing short of amazing-flare is
almost nonexistent.
Richard Wasserman
From Leica Mailing List;
....
I'd say that your experience makes you an expert ;-)
I send a Biogon 38 to John to have it re-coated, and fungus cleaned off
the middle element...well, needless to say, the lense is as new, of not
better...since the coating is far harder than the original coating it had
in the first place.
From Leica Mailing List;
Douglas,
I had JVS polish and recoat a 1950s Summarit which had serious cleaning
scratches bought for a song from Camera Exchange in Minneaoplis . It now
works and focusses just fine and produces beautiful bokeh wide open. My
favorite 50mm for portraits! Also I had JVS polish and coat the taking
lens (55 Distagon) on my Rolleiwide (which I had stupidly scratched after
the lens had been pristene for 30 years!) and again it takes very sharp
photos.
By my experience, lenses polished and recoated by JVS are as good (or
better) than new and they focus accurately.
My 2 cents
From Rollei Mailing List;
Hi all!
Just a few tips:
If the mirror in your Rollei TLR is in bad shape you can either order a
new mirror from a camera repairman, or get the old one recoated. The older
Rollei mirrors are silver coated and laquered for protection.
If you buy a new mirror, remember what camera model you have since they
have different sizes. The pre-war 4x4 cameras have smaller and thinner
mirrors, so if you cut a new mirror to fit you must have the viewing lens
focus adjusted.
I have ordered two new mirrors for 3,5 Rolleiflex cameras from a repairman
here in Sweden and will get the mirror for my Rolleiflex Sport 4x4
recoated at Sirius Optics in Kirkland, WA. They have good prices, $20 for
a silver- plus a SiO protecting coating.
http://www.siriusoptics.com/
/Patric
From Rollei Mailing List;
Properly, the mirrors in Rolleiflex TLR's should be first-surface
SILVERED, and not aluminized. This was a common home process for amatuer
astronomers until the last generation; the chemicals are easily obtained
and the instructions can be found in older amatuer-telescope making (ATM)
books.
Or look in any issue of SKY & TELESCOPE, where several firms doing such
work advertise.
Marc
From Rollei Mailing List;
[snip]
Marc,
I thought the mirrors WERE 1st surface silvered. Thanks for confirming
it. Now, in the books I've read on building 'scopes, they compare the
older silver method with the newer aluminium diffusion method. According
to these references, the aluminium doesn't quite reflect as much light as
the FRESHLY silvered mirrors, but the silvered mirrors would rapidly
tarnish, loosing their reflectance.
In the Rollei first surface mirrors, are there any steps to prevent this
tarnishing of the material?
I was looking at the aluminizing process for two reasons. 1) I was going
to have a scope mirror done anyway, and would just include the Rollei
mirror as well. 2) Everything I've read about the aluminizing process
says that it is rugged and longer lived than the silver process.
If anyone wants to correct my folly here? Thanks!
--
From Rollei Mailing List;
Craig
Please restructure your e-mail sender to use plain text. You appear to be
using some bizarre concoction of fonts.
Yes, silver is better than aluminium for reflectivity, unless you lived in
Pittsburgh (as I did) in the 1960's.
Best,
Marc
From Rollei Mailing List:
...
Maybe old Rollies but hardly later ones. Silvering is _very_ old
fashioned and very short lived. First surface silvering must be coverd
with a layer of lacquer to protect it from almost immediate oxidation. Its
typical to find the silvering of old cameras with front surface mirrors
has oxidised in spots due to the peeling of the lacquer, and, generally,
the lacquer has yellowed where it remains.
My c.1936 Rollei has a perfect mirror which appears to be aluminized but
I can't swear its the original.
----
From Rollei Mailing List:
....
Absolutely _fresh_ silver is slightly more efficient in the visible
spectrum but not outside of it, especially in the IR. The difference in
the visible range is only a couple of percent. It is definitely inferior
to Aluminum for astrophotographic uses. Since silver tarnishes so rapidly
it is _never_ used on telescope mirrors or instrument mirrors, and hasn't
been since about 1945.
Zeiss , at one time, definitely used silvering with an overcoating on
some mirrors. I have a couple of Mirroflexe bodies with sivered and
lacquered mirrors. The mirrors are a mess.
----
From Rollei Mailing List;
Richard Knoppow wrote:
Richard, I am stunned to find myself disagreeing with you, but your
posting flatly contradicts quite a bit of ATM literature I have in my
possession (bibliography available, grudgingly, on request!).
Simply put, silver does MUCH better -- 8 or 10 percent! -- when fresh, but
needs renewing every two or five years, depending on your climate.
Aluminium coatings are dim beyond measure in visual wavelengths, but do
last longer -- I own a Meade 1037 which Meade advised me to only have
recoated "when needed".
Those who bitch about the "dimness" of their Automat or MX Rolleis should
certainly have their mirrors recoated. Aluminium coatings would work.
But, to see what Carl Mydans or Capa saw, go for silver: the image WILL
be brighter and more useable.
Marc
From Rollei Mailing List;
Gene Johnson wrote:
Uh, silver is more reflective in visual wavelengths than aluminium, by 8
or 10 per cent.
Marc
Date: Wed, 25 Jul 2001
--- Josef Seidl JosefSeidl@web.de wrote:
Depending on whether you think a broken Polaroid OneStep
is a camera or not: there's a large front-surface mirror
inside each one. It's trapezoid-shaped, about 75mm high,
about 75mm wide at the bottom, and about 25mm wide at the
top. They seem to turn up a lot at junk stores and yard
sales.
Tim Victor
From Camera Fixing Mailing List;
Hi
Were the mirrors you used of the front-surface coated variety? Remember,
camera reflex mirrors are silvered on its front surface, unlike common
mirrors which are silvered 'under'. Focus deviations occur when this
coating is placed somewhere else other than where they should be, and that
light moving through a glass layer (as in rear-silvered common mirrors)
would be distorted.
Or were the toy mirrors made of metal (hence its reflecting surface is
already on the front)? The thickness of the material is also critical- a
replacement mirror should have the same thickness as the original to
retain focussing accuracy.
From Camera Fixing List;
a piece of glass has two surfaces, one nearest you is the front surface,
the back one is the rear surface. Regular mirrors are usually rear
surface mirrors, the reflective coating is on the back of the piece of
glass, so the glass protects it from scratches and dirt and esp. from H2S
and other pollutants in the air that might attack it (with moisture etc.).
A front surface mirror puts the reflective coating on the first or front
surface, with the glass behind it only as a support
the big deal in photography is that a rear surface mirror will have two
reflections, one from the front of the glass (weak) and one from the
reflective surface at the rear. A front surface mirror will have only one
reflection from the front surface. To eliminate the weaker but
disconcerting second image of a rear surface mirror, a front surface
mirror is used so you have only one image in view and focus accurately
the bad news is that front surface mirrors are VERY delicate, easily
damaged by touch and easily scratched (unless protected by SiO2 or other
coatings as in telescopes). Once damaged, you have to replace or somehow
recreate a single surface mirror at the precise plane of the original
mirror to keep focusing working etc. Most photo types will use tricks
from amateur astronomers to put a silver layer on glass (after cleaning),
but the silver is quickly tarnished (unlike aluminum reflective coatings).
older prisms have similar problems with flaking edges and separation and
may also need resilvering (or re-aluminizing); but this is a costly
process however the result can be a good bit (stop) brighter and cleaner
hth bobm
From Camera Fixing Mailing List;
lots of sources; from repair suppliers (microtools I presume), scientific
supply houses (like Edmund Scientific), "donor" bodies, and transplants
the most commonly cited is the Polaroid cameras (disposables) which have
thin mirrors in them. more examples at recoating and resilvering FAQ
pages:
http://www.smu.edu/~rmonagha/bronrecoatings.html
the biggie problem is matching the position of the front surface mirror
to the exact spot to achieve exact focusing; you can adjust the prisms
and/or screens a bit usually to adjust, but you can't usually put a
biggie mirror in place of a thin one ;-(
an ideal item would be an easily cut front surface mirror made on some
really thin glass (like a microscope slide cover, only bigger?) ;-)
another possible option would be some sort of really thin but highly
reflective film (mylar like, but without distortions of mylar?) - but I
haven't found the right stuff yet either.
best advice is be really careful around the mirror ;-) bobm
From Camera Fixing Mailing List;
On 26-Jul-01 Kelvin wrote:
These two surplus dealers sometimes have front-surface mirrors cheap:
Surplus Shed: http://www.surplusshed.com/index.cfm
(lots of optics, some pretty unusual)
C & H Sales: http://aaaim.com/CandH/index.htm
--Michael
From Rollei Mailing List:
you wrote:
Previous thread snipped...
All Planar and Xenotar lenses used on Rolleiflex cameras are coated.
Virtually all lenses made after about 1947 are hard coated. The
Rolleiflex E series dates from about 1957.
Multiple coating dates from perhaps 1980. Multiple layer coating is more
effective than a single layer but single layer coating very substantially
reduces flare. Flare increases rapidly with the number of glass air
surfaces, so it makes more difference in an f/3.5 Planar or Xenotar with
eight surfaces than in a Tessar with six.
The E Series Rollei also has internal baffles to reduce flare due to
light bouncing around inside the camera. These baffles were introduced in
about 1954. Generally Rolleis with grooved base adaptors for accessories
also have the baffles.
----
From Rollei Mailing List;
Richard Knoppow wrote:
Multiple coatings were developed in a co-operative effort between Zeiss
and Asahi in the 1960's; this was part of an effort to work out an
arrangement whereby Asahi would produce a camera and lens line in concert
with Zeiss to fill in the voide which would soon occur when Zeiss Ikon
went west. The deal fell through (Asahi did not feel that the Japanese
market would accept "Zeiss" lenses made in Japan, and Zeiss really wanted
to get out of the photographic optics business, as this was costing them
money by diverting resources from more lucrative items, such as medical
lab gear and submarine periscopes), and Asahi got the Zeiss-designed K BM,
while both shared their pooled multi-coating research.
Zeiss got the resulting "T*" process onto scientific and medical gear
around 1970; Asahi began to market "SMC" lenses in mid-'71. There are
those who argue that Zeiss was first to the photo marketplace, but I've
never seen any hard data which challenges Asahi's priority. Zeiss then
began to sell multi-coated optics which could be identified by this "T*"
marking around 1972. There are a number of late-model Rolleiflex TLR's
which have surfaced which lack the mark but which are clearly
multi-coated.
The inner circle of Zeiss researchers have concluded that Zeiss, for
reasons of economy, switched around 1975 to only using the multi-coating
process on all lenses, but that they only marked lenses with the "T*"
marking when the firm ordering the lens paid extra for this. Hence, both
Rolleiflex and Hasselblad received multi-coated lenses, but only Victor
paid the freight, and so only the Hasselblad lenses bore the "T*" mark.
Marc
From Rollei Mailing List;
in nordin's _hasselblad system compendium_ page 142 he indicates that
multicoating in general was introduced in the 70's.
"The third modification [to the hasselblad 80mm f2.8 C Planar] was when
T* multicoating was introduced (about 1971 and 1972 at Zeiss although
they started being supplied with cameras in 1972-73)"
by that time, the Rollei F has only a few years of life left in it
(according to Ian Parker, by 1977 the TLF is available only thru
special order and by 1979 the TLR no longer in production and are sold
only through existing stock.)
parker also writes of the special edition 2.8F platin (1984) which
features "a new HTF zeiss planar lens." 500 are made.
-rei
....
From Camera Fixing List:
Hi Kevin,
A mirror's silvering/reflective coating can be applied either on top of
its glass surface ("first surface") or beneath this. Common mirrors (such
as the one you find in your bathroom) are examples of the second type.
Reflex mirrors in cameras have their reflective coatings laid on its first
surface. This is done to cancel out the effects like distortion of light
when it passes through glass, or to allow precise measurement of the light
path's distance. In a reflex viewing system, as found in SLR or TLR
cameras, light is deflected by the mirror to the focussing screen. The
precise measure of this path's distance is critical. The mirror used to
deflect the light should not introduce an "extra distance" of its own or
distort the light beam, as what would likely happen if it were made to
pass through glass in a second-surface coated mirror (aka common mirrors).
Jay...
Date: Fri, 24 Aug 2001 There are single-coated lenses (originally the Zeiss T coating or equiv.). Take note that coating does NOT by itself improve transmission by default. Some lenses suffer "fogging" , which can be caused by one of several >My name is Gopalakrishnan, call me Gopal. I am a new member of From Topica Leica Mailing List
Apart from the fact that lens defects that have desirable effects might
Otto Giesenfeld
From Topica Leica Mailing List --- Luis From Leica Topica Mailing List: > The notion that lens defects can somehow improve image quality is one of the --- Luis
from camera fixing mailing list:
Date: Thu, 21 Feb 2002
From: "toolmaker48" toolmaker48@yahoo.com
Subject: Re: Cutting First Surface Mirrors
--- In camera-fix@y..., "Don Mills" dbmills@k... wrote:
Hi Don,
When you think 'padding', think 'bending', which will happen
when you press down on the glass. It's okay to use a layer of paper
towel or a sheet of soft paper to lay the glass on but not something
thick and spongy like a piece of carpeting.
Tip: Start your score inside the edge and end it inside the
opposite edge.
Suggestion: Get a piece of glass from an old storm window (it's
usually fairly thin). practice making little pieces until you get the
knack of it.
Robert
From Leica Mailing List:
Date: Sun, 3 Mar 2002
From: "kyle cassidy" kcassidy@asc.upenn.edu
Subject: [Leica] re: removing lens coating
i've successfully done it but putting the lens elements in a tub of
nailpolish remover (the kind filled with foam rubber with an X cut in the
middle you're supposed to stick your fingers in to remove the nail polish
(those of you who are not lea and never painted your nails black before
attending an Alien Sex Fiend concert will be looking blankly at the screen
now asking "what?"), be forwarned however that this also cleanly removed the
cement between lens elements. (leave it overnight) (i did this previously to
uncement lense which had partial seperation.) you may have luck removing
only the coating by pressing it down on top -- experiment with a nikon lens
before putting one of your trusty leitz lenses to the test.
just my .02. take it for what it's worth.
KC
From Leica Mailing List:
Date: Sun, 3 Mar 2002
From: Dr.Alexander.Kraus@gmx.de
Subject: Re: [Leica] Removing lens coating
It is true that toothpaste contains polishing agents, but its grain size is
about same as the finest grain size that's use in the optical industry. There
is no other way to remove a lens coating than to polish it off. Vapour
deposited mineral salts (like magnesium fluoride or aluminum oxide) are insoluble
in all common solvents. Maybe it would come off if soaked in concentrated
potassium hydroxide solution, but that would etch the glass surface and make
the lens unusable.
Old coatings are usually much softer than the glass underneath. If you
polish it by hand, it would take *very* long until a significant amount of glass
get grinded off. Just don't use a power tool with 10,000 rpm! I treated an old
Zeiss Sonnar, which had quite severe cleaning marks in the coating, with
toothpaste and had very good success. I couldn't see any negative impact on the
performance.
Alex
Date: Sun, 03 Feb 2002
From: yupiter3 ccm952@bellsouth.net
To: camera-fix@yahoogroups.com
Subject: [camera-fix] Re: rangefinder mirror glue
Bob & the group; I guess we can find out who last owned our Zorki
cameras:
http://www.detectoprint.com/default.htm
Here is why super glue (cyanoacrylate ) bonds to skin so well:
"In 1966 a special surgical team was flown to Vietnam, trained and
equipped to use cyanoacrylate adhesive. A quick spray over the wounds
stopped bleeding and bought time until conventional surgery could be
performed"
http://www.fensende.com/Users/swnymph/refs/glue.html
When I was on the Burroughs Optical memory project; I bonded many
mirrors with different adhesives.... A TOO fast drying adhesive may
warp a mirror....Our mirror vendors recommended the thickness to
longest dimension to be no less than 1:6 ..A thin mirror may warp; a
stocky mirror is a better design....Also remember that if the
adhesive dries (outgases) thru the already cured skin of adhesive ;
the central core may take along time ie weeks to dry.....We bonded 50
cent piece diameter mirror blanks to optical mounts; and recorded the
progression of the drying glue bond.....When we used RTV; the central
portion would take MONTHS to dry.. The ring of dried RTV was the same
as the RTV adhesive tube; it prevented it from drying... Thus we
found a U shaped blob of adhesive allowed the adhesive to dry
quickly....
Regards Philip
Jim Brokaw at jbrokaw@p... wrote:
>
> > I recommend staying away from super glue for gluing around glass. Super glue
> > (generically cyanoacrilite glues) have a strong attraction to moisture and
> > skin oils. They are used to 'develop' fingerprints on criminal evidence. The
> > suspect items are placed in an enclosed chamber with an open pot of cyano-
> > glue and the glue vapors form a frost-like coating anywhere there is even
> > minute deposits of moisture/skin oils. So these kinds of glues are a big
> > risk for contamination of optical surfaces... I learned this the hard way!
> > For anchoring a rangefinder mirror, what about the Pliobond glue that is
> > used for leather and rubber gluing?
...
From Leica Mailing List:
Date: Tue, 5 Mar 2002
From: Dr.Alexander.Kraus@gmx.de
Subject: Re: [Leica] Removing Lens Coating
> Why do you want to remove a lens coating? Because it is 'old" or because
> it
> is "defective", and does one relate to the other?
Certainly not because it is old. Usually I don't treat my lenses with
toothpaste ;-)
I did it in the past with some two lenses that had a "dull" coating on the
front lens. On an other occasion I tried to clean an old Summicron 50mm (7
element) which was very hazy. Allthough I wiped the element behind the
aperture *very* carefully with a microfiber coth soaked with isopropanol, the
coating came partially off. In order to have it recoated, I had to remove the old
coating completely. I was sucessful in using toothpaste for this purpose.
Alex
From Leica Mailing List:
Date: Tue, 05 Mar 2002
From: Javier Perez summarex@yahoo.com
Subject: Re: [Leica] Removing Lens Coating
BTW: I've seen several types of coating damage.
The typical kind is damage through abrasion,
that's to say light cleaning marks. Then there's fungus damage.
But I've also seen coating that seems to be chemically damaged
other than by fungus. One of my favourite lenses (Steinheil
35 Auto Quinaron - Exakta) has spots on the front glass that
could only have ocurred through chemical action. So I'm still
convinced that a coating remover must exist!
Javier
"John M. Sikes, Jr." wrote:
> Why do you want to remove a lens coating? Because it is 'old" or because it
> is "defective", and does one relate to the other?
>
> ----------
> >From: Dr.Alexander.Kraus@gmx.de
> >To: leica-users@mejac.palo-alto.ca.us
> >Subject: Re: [Leica] Removing Lens Coating
> >Date: Mon, Mar 4, 2002,
> >
>
> >>
> >> >As a practicing dentist for the past 25 years, I can tell you that
> >> >toothpaste not only will remove just about any lens coating, but will
> >> also remove a fair amount of the lens element itself. You'll have a cloudy
> >> lens in no time!
> > I don't dispute the abrasive character of toothpaste. But I can also ensure
> > you that I have sucessfully used toothpaste to remove an old defective
> > coating without getting a cloudy lens. I used a special toothpaste for
> senstive
> > teeth which contain less pumice (or finer paritcles). One time I messed a lens
> > up, but this was when I used a power tool for polishing. If you make a slurry
> > of toothpaste and some water and wipe the lens without too much pressure, it
> > takes quite a while untile the coating is polished of - and here we are
> > talking about a layer of approx. 300 nanometers. I frequently check the
> appearance
> > of the surface and as soon as the coating is gone, I stop wiping the lens
> > and wash the lens with water until the toothpast is completely gone. Even with
> > a 10x magnifier I wasn't able to see any cleaning marks or cloudy surfaces.
> >
> >> >Toothpaste contains varying amounts of pumice and is very
> >> >abrasive. I've seen patients over the years who are so aggressive with a
> >> >toothbrush and toothpaste that they have removed tremendous amounts of
> >> >tooth enamel such that the tooth has snapped in half due to
> >> >toothpaste-induced erosion. Tooth enamel is far harder than any lens I've
> >> >ever seen.
> >
> > What you describe is the result of years of abuse and the addtional impact
> > of agressive chemicals (acids) that are formed in the mouth.
> >
> >> >As an aside, toothpaste can remove scratches in your car's
> >> >paint or clearcoat quite nicely if used in small amounts on a wet rag.
> >
> > I know. Toothpaste is a perfect allround polishing aid :-)
> >
> > Alex
From Camera Fixing Mailing List:
Date: Thu, 21 Feb 2002
From: "camfix55" camfix@webtv.net
Subject: Re: Cutting First Surface Mirrors
Hi Don;
The secret to "Not scratching the silver side" is a very clean flat
surface.
Place your mirror stock against a stop or tape it down with masking tape so
your stock can't move. No dirt + no friction = no scratches. If your like me
and your straightedge slips halfway through the cut. Try taping that down also.
I never think of that till I end up with a tapered mirror that I have to stone
to get it to fit. A pair of clean cotton gloves or rag can be a confidence
builder when snaping off the cut . Helps prevent fingerprints also.
Keep your feet warm. Everett
Date: Sat, 26 Jan 2002
From: toolmaker48 toolmaker48@yahoo.com
To: camera-fix@yahoogroups.com
Subject: [camera-fix] Re:TLR mirrors
American Science and Surplus (http://www.sciplus.com/ ) is presently
selling rear view mirrors and a 25 x 38 beam spiller that could be
used for reflex cameras (either one is cheap). They often buy Edmund
Scientifics surplus or rejected optics.
Their inventory constantly changes but years ago I was able to buy
an 8 1/2" x 9" x 2mm sheet of FS material for only a few dollars.
At the very least, it's an interesting place to visit.
Robert
From rollei mailing list:
Date: Sun, 21 Apr 2002
From: Marc James Small msmall@infi.net
Subject: Re: [Rollei] Re: Seeking TLR parts/service
Mirrors can be resilvered at home. The process does involve some fairly
high-powered chemistry but, still, it can be done safely with a minimal
amount of care. This was the standard in amatuer astronomy circles until
the cost of aluminizing fell rather precipitously in the early 1970's. The
instructions for silvering are readily available in older amatuer
telescope-making (ATM) books such as Texereau, Thompson, or the like, and
there are probably a number of ATM's in your area who could help -- check
with your local Science Museum.
On the other hand, you can have your mirror aluminized at a couple of
places. Pick up a copy of SKY & TELESCOPE magazine and look for companies
that offer this service.
Marc
msmall@infi.net
From rollei mailing list:
Date: Sun, 21 Apr 2002
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re: Seeking TLR parts/service
you wrote:
>curtiscr@pe.net wrote:
>>
>>Ahem! Mirror makers, amateur and professional, that I knew back
>>in the 1950s and 60s were having them aluminized. It was standard
>>for commercially-made scopes such as Cave, Coast Instruments,
>>etc. Cave's were coated by Panchro Mirrors.
>
>Very few amatuer astronomers had mirrors aluminized until the prices
>dropped. Check out the adverts in S&T; for the early 1960's and for the
>1970's -- the prices fell and, when it became simpler to have the mirror
>coated commercially than to do it yourself, then the switch occurred.
>
>I am not discussing commercial telescopes (my '62 Questar has an aluminized
>mirror, as does my 1954 Fecker Celestar) nor am I denying that some
>amatuers did choose to aluminize. All of the books previously cited
>discuss the choice, as do Sidgwick and Howard.
>
>Silver, in the end, is better for visual use and aluminium for photographic
>or digital use, another factor in the change.
>
>Marc
>
>msmall@infi.net
The first book on telescope making I got, in junior high along about
1953, discussed aluminizing vs: silvering and stated that silvering had
just about fallen out of use. Perhaps they meant professional telescopes.
Aluminizing is done by vacuum deposition, a process which became much
more available after WW-2, as is demonstrated by availability of lens
coating. Lenses are coated in exactly the same way.
_Uncoated_ aluminum has somewhat less average reflectivity than _fresh_
silver. It has a wider band. Silver tarnishes very quickly unless protected
by laquer so its original reflectivity can be short lived.
Aluminum mirrors can be coated (and I think usually are now) similarly to
lenses. The coatings in the case of mirrors _increase_ reflectivity. A
coated Aluminum mirror is a match or superior to Silver.
Probably the best solution to a bad finder mirror is to find a
replacement. Probably cheaper than having it Aluminized.
The old process of silvering required the use of Mercury but there are
methods which do not.
I think someone posted a web link to one.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
from rollei mailing list:
Date: Sun, 21 Apr 2002
From: Marc James Small msmall@infi.net
Subject: Re: [Rollei] Re: Seeking TLR parts/service
Richard Knoppow wrote:
> _Uncoated_ aluminum has somewhat less average reflectivity than _fresh_
>silver. It has a wider band. Silver tarnishes very quickly unless protected
>by laquer so its original reflectivity can be short lived.
> Aluminum mirrors can be coated (and I think usually are now) similarly to
>lenses. The coatings in the case of mirrors _increase_ reflectivity. A
>coated Aluminum mirror is a match or superior to Silver.
A COATED aluminum coating will produce between 83% and 88% reflectivity at
visual wavelengths, while an uncoated silver coat will produce between 93%
and 95%, Richard. The situation is reversed for photographic and digital
uses. Hence, a fresh silver coating remains the best visual method. There
are professional telescopes being made as I write this which will have gold
or silver coatings to achieve better reflectivity at the wavelengths desired.
And a silver coating, in a dry and unpolluted climate, will last more than
5 years before there is a measureable drop in reflectivity. I live in a
wet climate with a fair amount of air pollution, so it might last six or
eight months here. I have forty-year-old aluminium coatings which are
still good to go.
Marc
msmall@infi.net
From rollei mailing list:
Date: Sun, 21 Apr 2002
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re: Seeking TLR parts/service
...
I don't know where you are getting these numbers. See the Optical Society
handbook and I think also the AIP Handbook of Physics for graphs of coated
reflectors. The reflectivity of a multiple coated metallic reflector is
well above 90%.
It doesn't take anything beyond oxygen to tarnish Silver. Its very
reactive. Certainly, in city conditions it will tarnish very fast.
I don't remember now how long the old Mount Wilson mirror was expected to
last between silverings, they had the equipment there at the telescope for
re-doing it. At the time this instrument was constructed there must have
been no air polution at all up there.
Silver makes good mirrors but the difference in visual brightness
compared to Aluminum is not great and they last practically forever.
Silvered mirrors should be laquered to prevent very rapid oxidation.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From rollei mailing list:
Date: Sun, 21 Apr 2002
From: Marc James Small msmall@infi.net
Subject: Re: [Rollei] Re: Seeking TLR parts/service
Richard Knoppow wrote:
> I don't know where you are getting these numbers. See the Optical Society
>handbook and I think also the AIP Handbook of Physics for graphs of coated
>reflectors. The reflectivity of a multiple coated metallic reflector is
>well above 90%.
These are the figures used by optical engineers, Richard. They are widely
published in the astronomical and telescope-making literature as well as in
manufacturer's literature. Zeiss and Questar both use 88% as the maximum
for coating aluminized coatings, as did Zoomar for their Reflectars.
Marc
msmall@infi.net
From rollei mailing list:
Date: Mon, 17 Jun 2002
From: Todd Belcher Todd.Belcher@Creo.com
Subject: Re: [Rollei] Coating Flaws in E Series
If the problem is only on the front surface of the front element, I would
suspect environmental damages rather than manufacturing problems. That being
said, I suppose it is possible the coating Schneider used was susceptible to
a particular form of environmental damage - fungus, moisture, heat??
Early Zeiss coatings on the 2.8 lenses were quite bad as well - very soft. I
have seen quite a few lenses where there is no coating left - completely
rubbed off. The front coating on the Zeiss 2.8 Planar should be a yellow
colour and these were reflecting true colour without the yellow tinge. Inner
elements of the same lens were obviously coated. Other early Zeiss 2.8
Planars I've seen had partial amounts of the front element coating left. It
seems that Zeiss did something to the coating after a few years because
later yellow tinged Planars seem fine.
todd
[quoting..]
I've seen this a number of times on lenses stored where there was a lot
of moisture. It may be the effect of fungus but I suspect it may be
something else.
Most coatings are Magnesium Flouride, a fairly hard and resistant
material. I don't know specifically what attacks it but have seen enough
lenses with damaged coatings, or damage which is much deeper than the
coating, to think it may be sensititve to moisture or the exudations of
fungus.
BTW, I also remember a runor that Schneider had coating problems in the
mid 1950s. My 2.8E shows some coating flaws on the outer surface but
neither of my Xenars do nor does a Componon enlarging lens from about the
same period. Actually, the Xenars are older, so may not have been coated in
the same way.
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From rollei mailing list:
Date: Mon, 17 Jun 2002
From: Bob Shell bob@bobshell.com
Subject: Re: [Rollei] Coating Flaws in E Series
Richard Knoppow at dickburk@ix.netcom.com wrote:
> BTW, I also remember a runor that Schneider had coating problems in the
> mid 1950s. My 2.8E shows some coating flaws on the outer surface but
> neither of my Xenars do nor does a Componon enlarging lens from about the
> same period. Actually, the Xenars are older, so may not have been coated in
> the same way.
I had two Symmars, a 150 and a 210 which I bought new from Burleigh Brooks
with a Cambo view camera around 1974. Both lenses developed this
characteristic flaking or pitting of the coating after several years. I
replaced both in the mid 80s with Symmar-S versions, and neither of those
has shown any sign of having this problem. At the time I thought maybe the
lens surface had not been adequately cleaned prior to coating.
Bob
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: Wed, 19 Jun 2002
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] THE FINAL WORD on Coating Flaws?
...
This may not be entirely a reflection of coating problems but may be
influenced by the attitude of the owners of various makes/types of lenses
or their perceived value, as well as simply the quantity of various lenses
around. There are lot of Leica lenses out there.
Vacuum coating technique was developed in a lot of places. Zeiss was
experimenting with it as early as 1935 and soft coatings were being
experimented with at very much earlier dates. These soft coatings were
applied by immersion of the lens in a solution which left the coating on
the lens surface. Some of these coatings simply rubbed off in ordinary
cleaning. Kodak used a type of soft coating on the internal surfaces of a
few of its lenses beginning about 1940.
Vacuum coating, or hard coating, began to become generally available
after WW-2. Major manufacturers began to offer coated lenses about 1946
although some of the smaller ones, Goerz, for example, did not generaly
coat lenses for some years after. There were a number of places offering
after-market coating, probably of quite variable quality.
I've had a little experience with vacuum coating in the dim, distant
past. Its tricky. I have no doubt that early coating had many problems.
Modern technique is to give the surfaces a final cleaning by electron
bombardment. Coating is done by evaporating a metallic substance in a
vacuum chamber. For multiple coating several differnet materials are
evaporated successively to very precisely determined thicknesses.
The coatings must be uniform and must stick to the glass.
The thickness of a single coating can be controlled by visual observation
but there are more accurate methods, and they must be applied to a multiple
coated lens if the coating is to work right.
Lens coating fits into the catagory of thin-film technology, a massive
field brought to an exceptionally high degree of advancement by the
semi-conductor industry.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
Date: Wed, 19 Jun 2002
From: "Kotsinadelis, Peter (Peter)" peterk@avaya.com
To: "'rollei@mejac.palo-alto.ca.us'" rollei@mejac.palo-alto.ca.us
Subject: RE: [Rollei] THE FINAL WORD on Coating Flaws?
Craig,
I had JVS do the recoating on one of my E2.8 Xenotars. It will look great,
but bear in mind the lens will have a slight color shift which is only
noticeable on transparencies. To get around this I use a R1,5 which
compensates when shooting trannies.
Peter K
Date: Wed, 19 Jun 2002
From: Douglas Anthony Cooper douglas@dysmedia.com
To: rollei@mejac.palo-alto.ca.us
Subject: [Rollei] Re: Coating and Collimating
> I had JVS do the recoating on one of my E2.8 Xenotars. It will look great,
> but bear in mind the lens will have a slight color shift which is only
> noticeable on transparencies. To get around this I use a R1,5 which
> compensates when shooting trannies.
This surprises me -- John made a point of explaining to me that he closely
replicates the original purple, but applies the coating at a much higher
temperature, which makes it harder. I was also under the impression that
coating colors don't really affect the color of transmitted light (although
that does seem a bit counterintuitive). How does the color shift manifest?
Also -- and this is a delicate matter -- Bill Maxwell has noted that a few
Rolleis have come back to him for recollimating after being recoated; there
is some concern that Focal Point's collimator is a touch off. I wouldn't
want to be the one to point this out to JVS, who is cl
Douglas Cooper
http://www.dysmedia.com
From rollei mailing list:
Date: Mon, 15 Jul 2002
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re: [RF List] Zeiss Jena 50/1.5 Sonnar
you wrote:
> Douglas Anthony Cooper wrote:
>>I've just come into possession of an aluminum-bodied Zeiss Jena 50/1.5
>>Sonnar in LTM. What's strange -- I believe -- is that it seems to have
>>coating (and should, as this is post-War, no?), but there is no "T" to be
>>found anywhere. I was told that all of the post-War East German lenses had
>>the T mark... The serial number is 2554708.
>>
>>The second oddity is that, although it has no cleaning marks on the exterior
>>surfaces, there do seem to be marks of some sort on the *inside* surfaces,
>>next to the diaphragm. Might have been opened, and cleaned badly? Who
>>knows. Still, a pretty clean lens; I'm looking forward to shooting with it
>>-- have never used the 50/1.5 Sonnar.
>
>2554708 dates from around the early War years and it certainly should be
>coated and marked with the "T". Yours seems to be a bit of an oddity if it
>isn't so marked. These coatings were rather soft and the internal markings
>might be an artifact of a drying coating.
>
>The 1.5/5cm CZJ LTM Sonnar is the most common of the LTM Zeiss lenses.
>These normally sell for between $200 and $500, depending on condition.
>They appear on e-Bay with some frequency.
>
>Marc
>
>msmall@infi.net
The Zeiss serial number list in McKeown's Guide indicates 1939 as the
year of manufacture. I don't think Zeiss was coating any consumer lenses
this early although they had the technology to do so.
I suspect this lens was coated aftermarket, perhaps at the same time it
was remounted to fit a Leica. There were a number of places offering to
coat existiing lenses right after WW-2. I have no idea how good a job they
did or if they all did hard coating.
Hard coating, as generally applied to lenses after about 1945 is done by
vacuum deposition. The most frequent material for single coatings is
Magnesium Flouride, although other materials can be used. MgF has close to
the ideal index of refraction and forms a very hard surface which is bonded
to the glass.
Earlier coating methods were chemical using various types of baths to
treat the surfaces. Most of these coatings were so soft they could be wiped
off. Kodak used this type of coating on a few premium quality lenses
beginning about 1940. A similar type of "soap film" coating was used
expermimentally by RCA for sound recording optics at about the same time
(the recorders use microscope objectives).
Beginning in about 1946 some manufacturers began routinely coating
lenses. Most had some trade-mark for the coating. In particular, Kodak used
a circle with an L in it for "Luminized", Wollensak used a large C with the
W in it for "Wocoated", Schneider used a triangle, at first white, then
red. I suspect the T* symbol of Zeiss began at about the same time.
I think B&L; used colored dots but they also used colored dots to indicate
color correction of aerial lenses. Getting any information about B&L; serial
numbers and other lens markings has proven impossible.
In any case, a fair number of older lenses were coated aftermarket. Some
I've seen had their serial numbers defaced for some reason.
In order to hard coat a cemented lens it must be separated befor coating
and recemented. This was a necessity for lenses cemented with Canada Balsam
since the heat of the coating process would very effectively destroy the
adhesive.
Zeiss appears to have had some working vacuum coating capability as early
as 1935.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From Rollei Mailing List:
Date: Mon, 15 Jul 2002
From: Marc James Small msmall@infi.net
Subject: Re: [Rollei] Re: [RF List] Zeiss Jena 50/1.5 Sonnar
Richard Knoppow wrote:
> The Zeiss serial number list in McKeown's Guide indicates 1939 as the
>year of manufacture. I don't think Zeiss was coating any consumer lenses
>this early although they had the technology to do so.
> I suspect this lens was coated aftermarket, perhaps at the same time it
>was remounted to fit a Leica. There were a number of places offering to
>coat existiing lenses right after WW-2. I have no idea how good a job they
>did or if they all did hard coating.
To the contrary, Richard, I own 1.5/5cm CZJ Sonnar T 2554180 in Contax RF
BM which was originally purchased in March, 1939, with a Contax III at the
old Roanoke Photo-Finishing about four blocks from where I write these words.
Zeiss began regular use of vacuum coating (the so-called "Smakula" method)
from at least 1937 onwards, though this was originally used primarily on
industrial, medical, scientific, and military equipment. Starting around
1939, regular coating of export commercial lenses began, and special runs
of LTM lenses were made from 1939 until 1945 for the Swedish market -- the
Germans had to pay for all those ball-bearings they were shipping home
across the Baltic! Zeiss licensed their method to JSK early on, but Leitz
and Voigtlander did not share in the largesse for quite a while.
Kodak and Wollensak in the US and Ross in the UK also developed the same
method at the same time, and much of the military gear produced by these
companies during the war was vacuum-coated.
Numbering systems are not a perfect gauge for dating a lens, in any event.
Zeiss numbers are all over the board from 1939 untill 1945, with a GENERAL
trend that earlier numbers (say, 2,5xx,xxx) are from the earlier war years,
while later numbers (such as 3,xxx,xxx) would be quite late. Postwar
numbering is even less consistent, as Zeiss shifted to block production
which might be off as much as three or four years. Leitz/Leica is equally
shaky.
Marc
msmall@infi.net
From rollei mailing list:
Date: Mon, 15 Jul 2002
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Re: [RF List] Zeiss Jena 50/1.5 Sonnar
you wrote:
>Richard
>
>No, the T (alone) meant it was coated, T* was for multi-coated.
>
>On the same subject, wasn't it some woman whose name was
>Isabel**** with Kodak, who did some important early work in
>coating?
>
>Jerry
>
Aaarghh. Yes, there was a woman with Kodak. I can't remember her name or
where to find it.
I will also have to find some very old references to the work at RCA, it
may have been done by the same person.
I will have to get to the library and check to see if they have
cumulative indexes for a couple of photo technology journals and the photo
history journal (not its right title). Someone must have written some
history of coating. Kingslake just barely mentions it.
I tried to find out from Thom Bell at Kodak when they first started
coating but he found all the records had been sent to RIT. At that time all
the stuff was still uncatalogued. Very frustrating.
I am curious about Marc's comments on early coating at Zeiss. Evidently
they did not mention this in their advertising, at least in the US.
The f/1.5 Sonnar has only six glass-air surfaces, same as for a Tessar,
so its not a flary lens. However, Zeiss made lots of lenses with eight
surfaces (Biotar for instance) where it makes a noticable difference.
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From Rollei Mailing List:
Date: Thu, 18 Jul 2002
From: Douglas Anthony Cooper douglas@dysmedia.com
Subject: Re: [Rollei] fungus
>
> Yes, Focal Point recoats lens surface. Peter K on the
> list has some past experience on this ...His email : peterk@avaya.com
>
> - - Jay
Yes, I've used John's service. He's great. I just spoke to him, and indeed
he does do rear elements. His prices have gone up, unfortunately: he now
charges $180 per lens surface.
Btw, something I neglected to ask him: is it true that fungus can spread
from one camera to another camera in the same bag? Do I have to quarantine
this Rolleiflex until I have it properly cleaned? (Some say that *even
after cleaning*, you can't be sure that the fungus is gone.)
From nikon mf mailing list:
Date: Thu, 13 Jun 2002
From: Michael Briggs michaelbriggs@earthlink.net
Subject: RE: Re-coating a Lens
On 14-Jun-02 NikonMF@yahoogroups.com wrote:
> Message: 20
> Date: Thu, 13 Jun 2002
> From: "mike_mcisaac" mike_mcisaac@yahoo.com
> Subject: Re-coating a Lens???
>
> Greetings from Alaska!
>
> I recently acquired a Vivitar Series 1 800mm F11 Solid Cat for taking
> pictures of grizzly bear tonsils from a safe distance with my trusty
> old F2. The lens is in mint condition except for one problem: there
> is fogging on the surface of one of the glass elements.
>
> I disassembled the optics (that was really easy - remove the lens
> retaining ring and everything came out into my trembling hand). The
> fogging would not clean up using the usual methods (lens cleaning
> solution and cotton balls followed by a microfiber cloth). It appears
> that as the coating on the glass has aged, it has deteriorated unless
> it came this way from the factory.
....
>
> Does anyone have any suggestions? Can this kind of defect be cured by
> polishing and then re-coating the lens element? Should I try cleaning
> it with gasoline and a wire brush? Should I leave well-enough alone?
> Should I call NASA - after all, this lens WAS made by Perkin-Elmer.
My suggestion is that your first rule should be "Do no harm.". With a rare and
valuable example of a fine optic, you would really regret damaging the lens
while making a perhaps unnecessary repair. So unless you are absolutely
confident that you know what you are doing because you are doing something that
you have done before (such as the cleaning procedure that you already tried),
send it to a professional. This isn't the lens to learn repair on.
The haze might be outgassed material from paint or lubricant that has condensed
on the glass. If so, it should be removable. Probably the best solvent is
acetone, but acetone will quickly damage plastics and paint, and is therefore
risky to use unless the lens has been disassembled to bare pieces of glass.
I have heard that optical labs use reagent grade acetone.
There are one or two camera lens repair services that will recoat lenses, but
AFAIK they only do single-coating. Probably the lens originally was made with
multicoating. The problem with multicoating is that it is much more
work and should be designed to the particular optical glass used--how would a
repair place know which glass was used? There are optical suppliers who will
custom multicoat the optical components that they sell.
It would best to remove the old coating without polishing, or extremely minimal
polishing. The curvature should not change on a scale of the wavelength of
light. I am very leery of repair services that say they will polish out
scratches.
Unless you are certain that the haze cannot be removed by cleaning and that it
is actually reducing the photographic performance of the lens, I think it would
be wiser not to try to have the lens recoated.
--Michael
From rollei mailing list:
Date: Tue, 27 Aug 2002
From: Paul Kollas pkkollas@gorge.net
Subject: Re: [Rollei] Re: Toothpaste
I tried ordinary run-of-the mill toothpaste to remove the coating on an
Yashinon lens. It didn't remove it at all.
pk
You wrote:
>> I had forgotten that toothpaste makes
>> a good and very gentle polish for all sorts of things.
...
From camera makers mailing list:
From: SOEL96@aol.com
Date: Thu, 5 Sep 2002
Subject: Re: [Cameramakers] Opaque Projector
regarding the first surface mirror-- american science and surplus usually
have a decent supply of these, usually around 10-15 dollars, and they ship.
http://www.sciplus.com/
joel
From: "Richard Knoppow" dickburk@ix.netcom.com
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Mirror for Zeiss Ikoflex
Date: Thu, 12 Sep 2002
"Wolfgang Haunzwickl" wolfgang-haunzwickl@t-online.de wrote
> Hi,
>
> we've bought an old Zeiss Ikoflex and the mirror is blind. We've found places
> who offer resilvering services in the US, but the price would be a lot higher
> than the price of the camera, especially as we'd have to ship it from Europe.
> We could replace the mirror if we could find a suitable mirror pane, 1mm thick
> and front side mirror. Does anybody know a source for such a glass or has a
> better idea?
>
> Thanks
You might find suitable mirror material at Edmund Optical,
I don't have the current URL but a Google search will find
it, they have an on-line catalogue. About the only other
thing is to use a mirror from some other camera.
Modern first surface mirrors are usually coated with
Aluminum rather than Silver. Aluminum has a very much longer
life. First surface Silver mirrors oxidize very quickly.
Most of them were coated with laquer for protection. Over
time the laquer flakes off allowing the air to get to the
silver.
You might also check with any amateur astronomy groups to
find out where they have their mirrors coated. Perhaps the
mirror could be cleaned and coated with aluminum along with
a telescope mirror.
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
From: Marv Soloff msoloff@worldnet.att.net
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Mirror for Zeiss Ikoflex
Date: Thu, 12 Sep 2002
...(quotes Wolfgang above..)
The classic source for fine optical mirrors is the cheap Polaroid pack
cameras. These have a noticable 45 degree angle behind the lens.
Carefully break open the plastic camera, and you can harvest a large,
fine piece of optical glass. I generally pay from 25 cents to one US
dollar for mine at garage sales, swap meets, etc.
Regards,
Marv
Date: Wed, 18 Sep 2002
From: dave dafouchey@comcast.net
Newsgroups: rec.photo.technique.nature
Subject: Re: silvered mirrors
If you know of a Copy Machine Shop or Technician they use First
Surface mirrors in most copy machines.
Dave Fouchey
"Hamish Niven" hamishniven@onetel.net.uk wrote:
>Hi I'm looking for mirrors of high enough quality and reflective on the
>front of the glass rather than the rear so I don't get double images when I
>use it. I live in the uk so any suggestion of outlets here would be really
>useful.
>
>Cheers
>Hamish
From: beasleyglb@mindspring.com (Gary Beasley)
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: growing beyond my Yashica Mat
Date: Sat, 19 Oct 2002
The bad mirror in the Rollei could probably be resilvered (actually
it's aluminized) by an astronomical mirror company. This is the one I
used last.
http://www.newportglass.com
From: "Sherman" sherman-remove_this@dunnam.net
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: growing beyond my Yashica Mat
Date: Sat, 19 Oct 2002
...
Scott,
Pick up an old Polaroid 600 or similar at a garage sale for $5. It will
have a very nice first surface mirror in it that you can use to replace the
one in the Rollei. You will have to trim it a bit but the price can't be
beat.
Also the Yashica should be making excellent contrasty images. Perhaps the
lens has some almost invisible haze on it? Maybe the back element or
between elements.
Sherman
http://www.dunnamphoto.com
From: Matthew Phillips mlphilli@hsc.vcu.edu
Subject: Re: [Rollei] Prism Problem?
>It could be two things that I can think of, either one of the shade tension
>springs has come undone, or one of the screen flatclips has worked itself
>loose. It's not hard to take off the finder and you'll probably see what's
>wrong with it right away.
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] lens coating on MX-EVS Xenar
>I've been searching the archives (yeah, this is how I have fun late at
>night), and I note an inconsistency regarding whether or not JSK had
>access to hard coating techniques in the mid-fifties. One poster
>(Marc?) says at one point that Zeiss did not license the technique out
>to JSK until later; another post suggests that JSK *did* have access to
>it. As my MX-EVS has a Xenar, I'm wondering whether I should worry about
>the coating evaporating...
>
>(Surely F&H wouldn't have installed both Tessars and Xenars at a time when
>one was hard-coated and the other not?)
>
>Doug
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com BR>
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: todd todd_belcher@bc.sympatico.ca
Subject: Re: [Rollei] Lens separation!
From: Robert Easthope reflectionsagain@writeme.com
To: rmonagha@post.cis.smu.edu
Subject: Lens Recoating
Make old mirrors look new again!
From: John Coz johncoz@erols.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Recementing Lens Elements
> > > I have a gorgeous 2.8E Planar, but...there is separation in a ring all
> > > around the edge of the taking lens... I've read about
> > > the work of John Van Stelton of Focal Point in Colorado. Can they make the lens as good as new?
> > > Greg Lawhon
From: Dirk-Roger Schmitt Dirk-Roger.Schmitt@dlr.de
Subject: Re: [Rollei] Recementing Lens Elements
From: Greg Lawhon glawhon@unicom.net
To: rollei@mejac.palo-alto.ca.us
Subject: [Rollei] Recementing Lens Elements
From: Andre Calciu a.calciu@anent.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Recementing Lens Elements
> I have a gorgeous 2.8E Planar, but...there is separation in a ring all
> around the edge of the taking lens (I assume this is occurring in the
> two front elements, which seems to be fairly common). I've read about
> the work of John Van Stelton of Focal Point in Colorado. Does anyone
> have a general idea what Focal Point charges to have the elements
> recemented? Can they make the lens as good as new? Thanks for your
> help.
>
> Greg Lawhon
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Single Coated or Multicoated Lens?
Date: Wed, 19 May 1999
> On Tue, 18 May 1999 shooter999 tai906@my-dejanews.com
> wrote:
>
> >Does it really matter? Single coated or Multi-coated. Like the SMC
> >Pentax lenses. Does it make the Pentax lenses the best because of their
> >patented coating process?
> >TIA.
>
> Lens coatings can make a huge difference !!!
>
> Generally you will find that the big 4 manufacturers offer better
> coatings than the independent manufacturers (With maybe 1 or 2
> exceptions !)
Newsgroups: rec.photo.equipment.misc
Subject: Re: sources URL Re: Lens polishing
Date: 22 May 1999
Subject: RE: [Rollei] Recementing Lens Elements
Date: Sun, 2 May 1999 12:12:52 -0700
Newsgroups: rec.photo.equipment.medium-format
Subject: Cheap TLR mirror replacement found?
Date: Thu, 27 May 99
From: Dirk-Roger Schmitt Dirk-Roger.Schmitt@dlr.de
Subject: Re: [Rollei] HFT Coatings
>At 08:32 AM 6/21/99 +0200, Dirk-Roger Schmitt wrote:
>>Well, I gave a lot of statements concerning the multicoating process. I
>>repeat it again: There is nothing special with it. You buy it together with
>>the coating plant from the coating plant manufacturer. A lots of myths are
>>concerned with it. No one is true. It is simple, it is cheap and it is not
>>licensed from Zeiss, and in most cases it is n o t specially designed for
>>the lens.
>
>Well, the process is patented, and the original patent is held jointly by
>Asahi and Zeiss; other manufacturers have similar, though not identical,
>proprietary processes. In any event, both Zeiss and Rollei contend that
>Rollei licenses the process from Zeiss.
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Are Leica users dummies?
Date: Wed, 16 Jun 1999
>>Here's a question. How badly affected does a lens need to be before
>>recoating is not worthwhile?
>>For example- with the Summicron, early lenses had soft coatings which
>>were easily damaged. So if only the coating was damaged recoating
>>seems a good idea. When a lens has a great many so-called cleaning
>>marks, ie multiple light scratches on the front and/or rear glass
>>surfaces, does that sound like a good candidate for recoating? I
>>haven't got a lens in this category; my only 50mm Summicron is a
>>fairly nice early collapsible screw version with some very minimal
>>damage to the coating that isn't really worth fixing yet. But I might
>>get a rigid Summicron and would like to know how bad the surface
>>marking has to be before I should pass on it. Is there any good way to
>>tell if the multiple surface scratching only affects the coating or
>>goes into the glass itself? Enquiring minds want to know.
Newsgroups: rec.photo.equipment.large-format
Subject: Re: How to polish a lens
Date: Thu, 22 Jul 1999
> I have successfully repolished lenses by preparing a pitch tool that is moulded to
> the lenses surface an polishing using cerium oxide optical compound. It takes
> considerable skill to prepare and manage the tool to maintain the figure of the
> lens, however it is sometimes possbile to remove rather ugly crazing and polish
> marks on uncoated lenses. Deep scratches cannot be removed this way.
>
> Bill Peters
>
> Hemi4268 wrote:
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Restoring an Ikoflex mirror
Date: Sat, 31 Jul 1999
From: "Jim Williams" jlw@nospam.net
Newsgroups: sci.chem,rec.photo.equipment.35mm
Date: Fri, 06 Aug 1999
>Hello,
>
>I am an chemist and an amateur photographer too.
>I have interested on cleaning lenses, and there are many
>articles about mechanical and chemical cleaning
>( The latter is mostly not recommanded, I know ).
>
>BUT does anybody know usual chemical composition
>of this fine layers ?
Newsgroups: rec.photo.equipment.35mm
Subject: Re: Composition of lens antireflex multicoating ?
Date: 18 Aug 1999
>The simplest antireflective (AR)
>> coatings ar quarter waves of magnesium fluoride or cryolite.
HRphotography
http://hometown.aol.com/hrphoto/myhomepage/index.html
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Getting lens polished/coated
Date: Sat, 02 Oct 1999
>I have a Konica Hexanon 1:3.5 F=135mm lens for my Koni-Omega that need the
>front element polished & recoated. Who do I contact. Does anyone have a
>ideal how much it will cost me. The coating is flaking off? I got it this
Subject: Lens Repair Experience
Date: 1998-05-13
[Ed.note: Mr. Covington is the author of a number of noteworthy books on
astrophotography...]
Newsgroups: rec.photo.equipment.35mm
Subject: Re: moisture on lens will damage coating on lens
Date: Wed, 3 Nov 1999
> hi I was doing night shots and run into a moisture problem. I unfortunaly
> found out later that the lens coating was damaged as a result of this
Clear skies,
Michael Covington
Author, Astrophotography for the Amateur
http://www.CovingtonInnovations.com/astro
Newsgroups: rec.photo.equipment.large-format
Subject: Re: Cleaning Old Lens' Surfaces
Date: Mon, 29 Nov 1999
> Actually, coatings are easier to scratch than bare glass.
> If its dusty blow as much surface dust as possible off using a hand
>operated blower. Then brush off what is left using a brush made of
>lens tissue by rolling a piece of tissue into a tube, then tear it in
>the middle and fold the two halves back so that the feathered end
>makes a brush. Use each once only, picking up as much dust as it will
>hold. Then toss it and make another.
Good advice.
> The surfaces can be cleaned using any standard lens cleaner. If the
>lens is quite dirty place the tissue across the lens and drop some
>cleaner onto it. Drag the tissue off the lens. Use fresh tissue each
>time.
> All this is a bit heroic for most cases but will be helpful when a
>lens has a lot of grit on it.
The classic technique for cleaning delicate optical surfaces.
> If there is oil on the surface try 91% Isopropyl alcohol. If that
>doesn't do it the standard optical shop cleaner is reagent grade
>Acetone. Acetone must be used with great care since it will dissolve
>paint and optical cement.
- Helge Nareid
Nordmann i utlendighet, Aberdeen, Scotland
From: Marc James Small msmall@roanoke.infi.net
To: hasselblad@kelvin.net
Subject: RE: cleaning marks
Date: Mon, 17 Jan 2000
From: Marc James Small msmall@roanoke.infi.net
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] lens coatings ?
>A friend of mine just bought a Rolleiflex 3.5F Xenotar (not sure what
>year yet) and I own a 3.5F Xenotar "whiteface" from near the end of the
>line. Were any of the Zeiss or Schneider 3.5F camera lenses multicoated?
msmall@roanoke.infi.net
From Rollei Mailing List:
Date: Sat, 19 Feb 2000
From: Richard Knoppow dickburk@ix.netcom.com
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Hazing
>Folks,
> Wasn't it the haze or tarnish on old lenses that
>tipped off the lens designers to coatings? In that
>case, why fool with something that is seemingly
>beneficial? A (very) small tad of extra speed and less
>ghosting or flare would seem to be a good thing.
>Perhaps my age enfeebled mind is not comprehending
>something here. If so, please enlighten me as to why
>one would be compelled to dismantle a lens (a tetchy
>situation without the proper equipment and work area),
>just to rub off some tarnish. As to removing dust, if
>it isn't REALLY bad, there is no earthly reason to
>remove it. Besides, lenses, being the leaky sieves
>they are, will gather dust internally no matter what
>you do, even packing them in Baggies and stowing them
>away in air-tight crypts, never to see the light of
>day again.
>
>Jon
>from Deepinaharta, Georgia
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 22 Mar 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: RE: [Rollei] 3.5 Planar question
>That is a factor of the coating technology.
>
>-_______________
>Andrei D. Calciu
>NEC America, Inc.
>No Archive
>
>
>One question here for you. The Xenotars have a bluish coating and the
>Planars almost a clear coating. Does this have to do with the layers or
>the
>coating specific to a lens? Seems odd since they are so similar in design.
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Thu, 23 Mar 2000
From: Alan Davenport adaven@teleport.com
Newsgroups: sci.astro.amateur
Subject: Re: Stripping mirror coatings Hello All,
most coating companies do the stripping of the old coating for me?
Date: Fri, 7 Apr 2000
From: calciua@hn.va.nec.com
Subject: [Rollei] Re: Rollei repair
Andrei D. Calciu
NEC America, Inc.
Date: Mon, 09 Aug 1999
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Lens recoating
>I read with interest the discussion of polishing and recoating Rollei
>lenses. I didn't readlize anyone was doing it. What is the
>approximate cost for Xenotars and Planars?
>
>I assume that the (re)coating used would be a "single" coating
>rather than "multi" coating. ??
>
>Aside from improved durability, would it be better than the original
>coatings from the 50's and 60's? I assume that van Stelten cannot
>equal the HFT and T* coating performance, but what, if anything,
>do we know about reflection-reduction of his coatings? Planar and
>Xenotar coatings have to contend with a lot of surfaces.
>
>Myron
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 12 Apr 2000
From: Dan Arsenault Dan.Arsenault@cportcorp.com
Reply to: hasselblad@kelvin.net
Subject: RE: coating on 'blad pol filters
From Hasselblad Mailing List:
Date: Sat, 15 Apr 2000
From: Marc James Small msmall@roanoke.infi.net
To: hasselblad@kelvin.net
Subject: RE: SWA and filter
>It's probably not a coated lense, since
>it's from 1954
Date: Mon, 17 Apr 2000
From: ULF S JOGREN ulf.sjogren@mbox310.swipnet.se
To: hasselblad@kelvin.net
Subject: SV: biogon coating
Date: Mon, 17 Apr 2000
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: SV: biogon coating
From: Scott Rychnovsky srychnovnospam@uci.edu
Newsgroups: sci.astro.amateur
Date: Thu, 08 Jun 2000
Subject: Mirror Refiguring Service
Newsgroups: rec.photo.equipment.35mm
Date: Tue, 20 Jun 2000
Subject: Re: What's in Lens Coatings
> I just got a B+W filter that came with a little booklet saying that the
> filter's multi-coating consisted of "metallic dioxide," or something
> like that. That got me wondering: just what goes into lens coatings, how
> are coatings made, how are they applied? Can anyone give a brief answer?
>
> Thanks,
>
> Joe
Date: Thu, 10 Aug 2000
From: curtiscr@pe.net
Subject: Re: [Rollei] Rollei mirror refurbishing
Curtis Croulet
Temecula, California
Date: Fri, 11 Aug 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Rollei mirror refurbishing
>you write:
>
> My c.1936 Rollei has a perfect mirror which appears to be aluminized but
> I can't swear its the original.
> ----
>If you compare a silver mirror with aluminum side by side, it is easy to tell
>the difference--silver is brighter, while the aluminum has a greyish-blue
>tone by comparison. However, this is most easily observed on back-silvered
>mirrors such as the ones in our bedroom (one Victorian, one modern) which are
>relatively well protected from tarnish. On my old cameras, some of the
>mirrors are almost unscathed, while others are a wreck. Apparently once they
>start to go, they go fast.
>JMcFadden
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Sun, 13 Aug 2000
From: Vincent Chan v7chan@acs.ryerson.ca
Subject: Re: [Rollei] Rollei mirror refurbishing
From Leica Mailing List:
Date: Sat, 19 Aug 2000
From: "Erwin Puts" imxputs@knoware.nl
Subject: [Leica] History of coating
Date: Thu, 05 Oct 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] blue-green coating hue
>Well, repolish/recoating can be done without affecting the lens formula
>(i.e., radius, curvature, etc). The actual activity involved means the
>coating is buffed off the lens affter heating the lens at about 200
>degrees.
>
>If a lens defect is big enough to be felt when you run a fingernail over
>it, than it is non-repairable (at least non repairable without turning your
>Planar into a Trashar).
>
>There are many risks involved with this repolish job. The heating can lead
>to de-cementing, or worse, to a heat-induced fracture in the lens.
>The recoating does not affect the lens formula if done properly. The amount
>of coating deposited on the lens is negligeable and will not change the
>lens formula.
>
>De-cementing can really make Coke-bottoms out of a good lens. Once
>de-cemented, the lens must be centered and the amount of glue must be
>minimal and properly cured in order to avoid destroying the work of the
>Lens Gods. An optical bench is mandatory for this operation. Doing it at
>home, on the kitchen table is definitely a no-no.
>
>-_______________
>Andrei D. Calciu (VA-4270)
>NEC America, Inc.
>14040 Park Center Dr.
>Herndon, VA 20171-3227
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Tue, 17 Oct 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] IWC watches, was ? Who cares, what it was? NOW
XENOTAR VS PLANAR
>Do other people seem to notice that there are more Xenotars with cleaning marks out
>there than Planars? Was/is the coating on the Planar harder than the Xenotar? Or is
>it the psychological explanation that people paid less for the Xenotar (usually),
>therefore they treated them like junk in the long run?
>
>Cheers,
>
>Lucian
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 4 Oct 2000
From: Jonathan Prescott jonpre@uswest.net
Subject: Re: [Rollei] blue-green coating hue
From: David Kabelik kabelik@asu.edu
To: rollei@mejac.palo-alto.ca.us
Sent: Wednesday, October 04, 2000
Subject: Re: [Rollei] blue-green coating hue
> How much does it cost to re-coat and polish the lens?
>
> Thanks,
> David
Date: Thu, 5 Oct 2000
From: calciua@hn.va.nec.com
Subject: [Rollei] Re-coating lenses by Focal Point
Date: Thu, 5 Oct 2000
From: calciua@hn.va.nec.com
Subject: Re: [Rollei] blue-green coating hue
From: photo-for-sale@egroups.com
Date: Sun, 12 Nov 2000
From: herbert c maxey mircraft@juno.com
Subject: Re: NEW GUIDE
Date: Fri, 5 Jan 2001
From: "Kent Gittings" kent@ism.com
Subject: RE: Ghosts and rays (long)
Date: Thu, 11 Jan 2001
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Re: Scratched 2.8 C lenses
>I always assumed that the coating on the outer surface
>of the front element was a hard coat put there to keep
>the surface from getting scratched.
Date: Thu, 11 Jan 2001
From: ShadCat11@aol.com
Subject: Re: Re: [Rollei] Re: Scratched 2.8 C lenses
Date: Thu, 11 Jan 2001
From: Marc James Small msmall@roanoke.infi.net
Subject: [Rollei] Coatings in World War II
>During WW 2, coated optics were considered so valuable that repair shops
>aboard capital ships were equipped with vacuum devises to recoat optical
>equipment in which the soft coatings of the day wiped or weathered off. I
>was told this by a repairman who had served aboard a carrier as precision
>equipment maintenance mechanic. He said almost all carriers and battleships
>had such capabilities, even many cruisers.
Date: Fri, 12 Jan 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: RE: [Rollei] Coatings in World War II
>How about the coatings right after WWII? Does this mean that we have be
>extremely careful with the coated Tessars of the late Automats?
>
>Siu Fai
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Wed, 10 Jan 2001
From: "Kotsinadelis, Peter (Peter)" peterk@avaya.com
Subject: RE: [Rollei] Re: Scratched 2.8 C lenses
Date: Wed, 10 Jan 2001
From: Andrei.Calciu@hn.va.nec.com
Subject: RE: [Rollei] Re: Scratched 2.8 C lenses
2.- reduces flare
3.- increases light transmission
Andrei D. Calciu
Date: Thu, 11 Jan 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: RE: [Rollei] Re: Scratched 2.8 C lenses
>>Date sent: Wed, 10 Jan 2001
>>From: Richard Knoppow dickburk@ix.netcom.com
>>Subject: RE: [Rollei] Re: Scratched 2.8 C lenses
>> Early designers tried to avoid glass-air surfaces by using cemented
>>elements werever possible. However, this is a very limiting approach to
>>design. Once effective coatings became available the whole approach to lens
>>design changed. The Xenotar was one of the first designs to take advantage
>>of using air spaces as lenses.
>>....
>The airspaces in the Planar P. Rudolf 1896 seem quite similar to
>those on the Xenotar U.S patent date 1952.
>and didn't Taylor take out a patent in 1904 on the use of acids to
>tarnish the surfaces of lenses to reduce reflectivity?
>In the interests of historical nit picking
>In the interests of historical nit picking
>All the best
>Larry Cuffe.
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Fri, 12 Jan 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: RE: [Rollei] Coatings in World War II
>How about the coatings right after WWII? Does this mean that we have be
>extremely careful with the coated Tessars of the late Automats?
>
>Siu Fai
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
From: "Mike" NEDSNAKE@email.msn.com
Newsgroups: rec.photo.equipment.medium-format
Subject: Re: Cleaning mark on lens,what can be done?
www.mfcrepair.com
> Would appreciate some suggestions.I have a lens that has some slight rub
> marks on the inside element.Not a scratch.It is like the purple coating
> has been rubbed off.Can it be polished to reduce it?Or will it be made
> worse?Can I send it back to the manufacturer for recoating? Thanks in
> advance
Date: Sun, 28 Jan 2001
From: "R. Peters" torx@nwrain.net
Subject: [Rollei] Re "silvering" mirrors
Date: Thu, 25 Jan 2001
From: Bob Shell bob@bobshell.com
Subject: Re: [CONTAX] OT.. P&S;
Date: Wed, 21 Feb 2001
From: Marc James Small msmall@roanoke.infi.net
Subject: [Rollei] T* and HFT
>They say theirs is different. I know if I hold my 80/2.8 Planar HFT
>next to a Hasselblad 80/2.8 T* the reflections are different, with the
>Rollei lens reflecting more blue-green to my eye.
Date: Sun, 11 Mar 2001
From: Gene Johnson genej2@home.com
Subject: Re: [Rollei] Rollei TLR mirrors
> Ajit Cheema wrote:
>
> I had posted a query on the RUG regarding this, but had only one
> answer. So, I am trying again.
>
> I have two Rolleiflex TLRs with badly damaged finder mirror coatings.
> Where can I find replacement mirrors? Or else, where can I have them
> resilvered or aluminized? I have been searching the web and find
> various references to Focalpoint Lens, QSP, Spectrum, Clausing etc.
> but am yet to find a contact address or phone number.
>
> I would appreciate all inputs from the group on this. Thank you!
>
> Ajit Cheema
Date: Mon, 12 Mar 2001
From: bigler@ens2m.fr
Subject: Re: [Rollei] OT Alumin(i)um vs. silver mirrors
Emmanuel BIGLER
bigler@ens2m.fr
Date: Sat, 17 Mar 2001
From: J Patric Dahlén jenspatricdahlen@hotmail.com
Subject: [Rollei] Mirrors for 4x4 Rolleiflex
Date: Sun, 18 Mar 2001
From: ajit1 ajit1@home.com
Subject: [Rollei] Re: Rollei TLR mirrors
H.L.Clausing
8038 N. Monticello
Skokie, IL 60067
USA
Ph:847 676 0330 Fax:847 676 2930
website: www.clausing.com
Aluminum Coating
807 Rutherdale
San Carlos, CA 94070-3733
USA
Ph: 650-593-6277
Website: www.sirius.com/~alcoat ( takes a while loading )
E-mail: alcoat@sirius.com
Date: Fri, 23 Mar 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: RE: [Rollei] Newbie.What to look for to exclude coating separation
>>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.
>
>Is there a way to fix this? Anybody has experience with this and how much
>does this generally cost? The Sonnar of the Tele-Rollei I have played with
>is seperating and I was wondering if that can be fixed.
>
>Siu Fai
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Mon, 28 May 2001
From: Disfromage@aol.com
Subject: Re: [Leica] Re: Cleaning Marks/ Recoating
>Some reputable experts suggest that if you have a lens recoated at Focal
>Point, it will be better than new (or at least as good). Ken Ruth (another
>legendary repairman) told me that it's impossible to grind and recoat a
>lens
>without doing damage.
>
>I am, in short, confused. Anyone have hard facts regarding this?
Date: Mon, 28 May 2001
From: "Austin Franklin" darkroom@ix.netcom.com
Subject: RE: [Leica] Re: Cleaning Marks/ Recoating
Date: Wed, 30 May 2001
From: Cummer Family cummer@asiaonline.net
Subject: [Leica] Re: Grinding and recoating lenses
Howard.
Date: Sat, 30 Jun 2001
From: J Patric Dahlén jenspatricdahlen@hotmail.com
Subject: [Rollei] Mirror recoating
Date: Thu, 10 Aug 2000
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Rollei mirror refurbishing
msmall@roanoke.infi.net
Date: Thu, 10 Aug 2000
From: Craig Stewart reddwarf@nbnet.nb.ca
Subject: Re: [Rollei] Rollei mirror refurbishing
> Properly, the mirrors in Rolleiflex TLR's should be first-surface SILVERED,
> and not aluminized. This was a common home process for amatuer astronomers
Craig Stewart, VE9CES
reddwarf@nbnet.nb.ca
Date: Thu, 10 Aug 2000
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Rollei mirror refurbishing
msmall@roanoke.infi.net
Date: Thu, 10 Aug 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Rollei mirror refurbishing
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Thu, 10 Aug 2000
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Rollei mirror refurbishing
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Fri, 11 Aug 2000
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Rollei mirror refurbishing
> Absolutely _fresh_ silver is slightly more efficient in the visible
>spectrum but not outside of it, especially in the IR. The difference in the
>visible range is only a couple of percent. It is definitely inferior to
>Aluminum for astrophotographic uses. Since silver tarnishes so rapidly it
>is _never_ used on telescope mirrors or instrument mirrors, and hasn't been
>since about 1945.
> Zeiss , at one time, definitely used silvering with an overcoating on
>some mirrors. I have a couple of Mirroflexe bodies with sivered and
>lacquered mirrors. The mirrors are a mess.
msmall@roanoke.infi.net
Date: Fri, 11 Aug 2000
From: Marc James Small msmall@roanoke.infi.net
Subject: Re: [Rollei] Rollei mirror refurbishing
>I know that dealing with collectible things sometimes requires a
>different mind set than I posess, but do you really think giving up the
>extra brightness and durability that aluminizing gives is a fair price
>to pay for the authenticity?
msmall@roanoke.infi.net
From: Tim Victor timvictor@yahoo.com
To: camera-fix@yahoogroups.com
Subject: Re: [camera-fix] mirrors
> Any non-camera source for getting the mirror material?
TimVictor@yahoo.com
Date: Tue, 24 Jul 2001
From: J-2 nikitakat@edsamail.com.ph
Subject: Re: Re: [camera-fix] mirrors
Date: Thu, 26 Jul 2001
From: Robert Monaghan rmonagha@post.smu.edu
To: camera-fix@yahoogroups.com
Subject: front vs rear surface mirrors Re: Re: [camera-fix] mirrors
Date: Thu, 26 Jul 2001
From: Robert Monaghan rmonagha@post.smu.edu
To: camera-fix@yahoogroups.com
Subject: Re: front vs rear surface mirrors Re: Re: [camera-fix] mirrors
Date: Thu, 26 Jul 2001
From: michaelbriggs@earthlink.net
To: camera-fix@yahoogroups.com
Subject: [camera-fix] Re: front vs rear surface mirrors
> Are there good sources for front-surface mirrors, therefore?
Date: Sat, 28 Jul 2001
From: Richard Knoppow dickburk@ix.netcom.com
Subject: Re: [Rollei] Choosing TLR
>No, Im not planning to shoot in 220.
>But I want to know are all E Planar models coated? When was the first
>production of such model?
>
>Xosni
Richard Knoppow
Los Angeles,Ca.
dickburk@ix.netcom.com
Date: Sat, 28 Jul 2001
From: Marc James Small msmall@roanoke.infi.net
Subject: [Rollei] Multi-Coatings
> Multiple coating dates from perhaps 1980.
msmall@roanoke.infi.net
Date: Sat, 28 Jul 2001
From: shino@ubspainewebber.com
Subject: Re: [Rollei] Choosing TLR
Date: Thu, 26 Jul 2001
From: J-2 nikitakat@edsamail.com.ph
Subject: Re: Re: Re: [camera-fix] mirrors
From: kelvin <kelvinlee@pacific.net.sg>
To: camera-fix@yahoogroups.com
Subject: Re: [camera-fix] Digest Number 70
hello Gopal
These are old questions!
No, not all lenses have coatings. There are uncoated lenses (typically
before about 1930s when Zeiss invented the "T" coating. For cheap Japanese
lenses, into the 1960s).
There are multicoated lenses (post late 1960s , when Pentax and Zeiss
toghether invented it). The material is made from an assortment of
minerals, you could probably learn more about it doing a google search for
"lens coating technology". The minerals used give you the colour.
Just beacuse you see coating of a deep colour, it does not necessarily
mean it's multicoating.
Lens coating reduces the reflections off any given surface of glass.
Within the camera lens, it is used to reduce internal reflections between
lens elements. On the front, it is used to reduce reflections off the
front glass. These serve to increase overall transmission characteristics
of the lenses from a typical 80%+ to about 99% with multicoating.
Coating is more useful in multi-element lenses, esp. zoom lenses which may
have 10 elements in 8 or 9 groups. In the old days, designs were kept to a
minimal of air/glass surface e.g. Tessar design, triplet designs ... so
multicoating these old lenses do not make significant difference.
Someone else may give you a more precise explanation, but this is the gist
of it.
As to your second question, this is a function of the coating material,
storage conditions determined by temperature and humidity levels. And of
course, handling. Lenses deteriorate in part because of condensation
settling on the elements, or dust . A cleaning will solve this ...and to
some degree, fungus growth.
common factors:
1. evaporation of oils in the helicoid settling on the glass surface
2. condensation
3. fracture of the cement in the compound element
4. characteristic changes in the glass element
To some degree , 1 & 2 can be cleaned. No. 3 will involve a complex
process of removing and recementing the elements and realigning them.
Costly. SK Grimes does it for expensive large format lenses.
No. 4 usually occurs beause of the inherent materials used to make the
lens which do not age well. For example, Leica RF lenses from the 1930s
are commonly fogged. Pentax and Canon super-fast lenses from the 1960s are
extra yellow because of thorium used in the glass e.g. Super-Tak 50/1.4,
35/2.0 , Canon FD35/2.
You can read more about this at sites like photo.net and others. Do a net
search!
....
"Camera-fix". I own a Ricoh XR-8, with Rikennon 28-70. I was silent for a
few days to observe if I am at the right place. Now I am so happy to be
here.....!
>
>I have a few questions, answers to which were not so very forthcoming at
other places:
>
>1. All lenses have coatings. Any idea(s) on what material the coating is
made of and how it functions?
>
>2. How long does the coating last? In effect, how long is a lens a good
lens. I am sure the performance of the lens detoriates over a period of time.
>
>Thanks in advance.
>
>Regards,
>Gopal
Date: Fri, 24 Aug 2001
From: "Otto Giesenfeld" <otto.giesenfeld@springtime.nu>
Subject: RE: Lens coating color
save some post-processing work, there are some theoretical
justifications stemming from the limited tonal range of photographic
film. For example, in high-contrast scenes, a low-contrast lens may
actually produce more shadow detail than a modern high-contrast lens. If
either the extreme highlights or the extreme shadows captured with a
high-contrast lens lie outside the dynamic range of the film, it is
unfortunately not possible to reliably simulate the effect of using a
low-contrast lens by processing the captured image data.
This said, in most photographic situations, modern high-contrast lenses
are certainly preferable, and it should also be possible to emulate the
effect of an older lens by exposing through a weak softening filter.
Differences in the rendering of in-focus and out-of-focus regions,
respectively, are of course also impossible to simulate by image
processing, since the distance information is lost in the
two-dimensional image. (Unless perhaps a stereo camera is used.)
Date: Fri, 24 Aug 2001 14:54:38 -0400 (EDT)
From: *- CHILLED DELIRIUM -* <sfunp@scfn.thpl.lib.fl.us>
Subject: Re: Old lenses
On Fri, 24 Aug 2001, David Young wrote:
> I cannot agree more, Mark! I shoot mostly with the "old" (1969) 90/2-R and
> mostly informal portraits at that. The perspective is ideal and the lens
> is tack sharp. If the new APO 90/2 is sharper (contrasiter?), I wouldn't
> want it - particularly for photographing women!
My view on this is that in my case, most of my photographic
problems and compromises are made to circumvent contrast
problems. Excess contrast, for the most part. I suppose if I lived
in Oregon or Washington State it might be the other
way around, but in the warm climes it's excess. As any schoolboy
knows, older lenses tend to have more flare than the latest
ones. This flare acts as a form of pre-exposure, adding to shadow
detail and lessening contrast (read Adams on this, with uncoated
lenses it was at least one paper grade's worth !). Yes, when one
shoots into the sun, it can cause problems, but...look at pics from
the single-coating days, and you'll see that Bischof, Schuh, HCB,
et al all managed to "get by" on equipment that rank amateurs
today, as good little pawns of the industry, look down upon
with disdain. Learn how your tools work, become intimate with them,
learn their strengths and weaknesses and how it all fits in with your
perosnality, vision and what you're out to photograph. No
one throws out a Stradivarius or an old bottle of Chateau-Laffite because
there's new ones around. Obsophilia is just as dumb as neophilia.
So I treasure my older lenses, and they allow me to make images that
I cannot with my current optics. This is not a put-down of
the latest & greatest, just a simple reality.
Date: Fri, 24 Aug 2001
From: *- CHILLED DELIRIUM -* <sfunp@scfn.thpl.lib.fl.us>
Subject: Re: Lens coating color
On Fri, 24 Aug 2001, Anthony Atkielski wrote:
to this...
> > low-contrast lens may actually produce more
> > shadow detail than a modern high-contrast
> > lens.
>
> Low contrast always obscures detail. If you believe otherwise, I'd like to
see
> images that prove your belief.
This is untrue for shadow detail.
> main branches of photo mythology.
I suggest you buy and read Adams' books...this is covered clearly. Adams
even states that Paul Strand and another cinematographer realized this
as coated lenses began appearing on the market. It's worth at least
one paper grade of extra detail in the shadows. To some people,
this is eminently useful. YMMV.
Plus many low contrast lenses have very high
resolution and viceversa. This is hardly a secret.
When you read lens tests, you may run across the phrases
"High contrast at the expense of resolution, or
High resolution at the expense of contrast".
Date: Wed, 17 Oct 2001
To: rollei@mejac.palo-alto.ca.us
From: Richard Knoppow dickburk@ix.netcom.com>
Subject: Re: [Rollei] bright screens
you wrote:
>I pulled out my jewelers screwdriver to examine my 2.8D screen and was
>startled to see the mirror was perfect. I can't imagine how the screen
>became so dirty and scratched. I've only looked at 45 or 50 Rollei screens
>of various models and eras, and might be persuaded as to some theory
>involving the quick-release screens, but I can't figure out the scuffs and
>scratches on those non-removable screens.
>
>Was dragging a rollei screen behind your baaad motor scooter Vespa a popular
>activity back in the sixties? Enlighten me, because a camera store filled
>with 4 20-and 30-somethings couldn't understand how the inventory of 6
>rolleiflexes and -cords with nonremovable (screw) hoods were so scratched.
>
>-Robin
>
Some of these mirrors are pretty soft. All it takes is one cleaning with a grit filled cloth to do up the mirror.
You can get a clue as to the mirror condition by looking through the
finder lens. If its flaky looking it needs to be recoated. I've had some
disagreement with Marc about what later Rollei mirrors are coated with but
there is no doubt those up to probably 1950 are silvered. Silered first
surface mirrors are very vulnerable to oxidation so they are coated with
laquer. The laquer can become yellowed but it can also flake off after a
time. When that happens the silver underneath blackens from oxidation.
Modern first surface mirrors are usually aluminized. The aluminum coating
is not quite as efficient an reflector for visible light as _fresh_ silver
but it is very resistant to oxidation. The reflectance can be improved by a
coating something like a lens coating. Chemically pure Aluminum develops a
coating of oxide one molecule deep over the surface, which prevents further
oxidation unless its damaged.
Mirrors of either kind should be blown off and cleaned by dragging a lens
tissue dampened with lens cleaner across the surface once. The tissue is
not pressed against the mirror, just dragged across it. Toss it after one
use. This is also a good way to clean dusty lenses.
Again, first surface mirror surfaces, regardless of coating, are very
delicate.
>Marc James Small wrote:
>
>> Leslie E. England wrote:
>> >I recently obtained an Old Standard Rolleiflex and have used it several
>> >times. I use normally a Leica M2, and I'm struck by how dim the
>> >focusing screen is on the Rollei.
>>
>> Your problem almost certainly arises NOT from a "dim screen" but from a
>> desilvered mirror. After almost seventy years, the mirror has probably
>> lost all or most of its silvering.
>>
>> Easily fixed: remove the mirror and send it to one of the places which
>> advertises in SKY & TELESCOPE for exactly this service.
>>
>> Marc
>>
>> msmall@roanoke.infi.net
----
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com
Date: Tue, 13 Nov 2001
Subject: Re: [Rollei] Petri Color 35 vs Rollei 35
From: Bob Shell bob@bobshell.com>
To: rollei@mejac.palo-alto.ca.us>
> From: Jerry Lehrer jerryleh@pacbell.net>
> Date: Mon, 12 Nov 2001
> To: rollei@mejac.palo-alto.ca.us
> Subject: Re: [Rollei] Petri Color 35 vs Rollei 35
>
> However, I have been thinking lately of a RF camera.
> What does the RUG think of the Leica CL?
Rangefinder accurate but prisms prone to flaking of silver. I don't know if
replacement parts are still available. Rangefinder works properly only with
the lenses made for the CL and will be slightly off with other lenses.
Shutter reputed to be troublesome but I never had one come in for shutter
problems, always rangefinder desilvering.
Meter is very accurate but can't be used with a few lenses which protrude
into the body too far.
Bob
Date: Thu, 15 Nov 2001
Subject: Re: [Rollei] Planar lens design changes from 2.8E to 2.8F
From: Bob Shell bob@bobshell.com>
To: rollei@mejac.palo-alto.ca.us>
> From: Kip Babington cbabing3@swbell.net>
> Date: Wed, 14 Nov 2001
> To: rollei@mejac.palo-alto.ca.us
> Subject: Re: [Rollei] Planar lens design changes from 2.8E to 2.8F
>
> FWIW, my understanding is that John Van Stelten does single layer
> coating of lenses (and very well, too, from what I've heard) but that he
> does not do multicoating. I've read somewhere, probably on this or the
> Leica list, that multicoating is a very involved process that takes a
> substantial industrial plant to do, so that basically only the lens
> factories are equipped to do it.
The problem is really that different lens designs and glass types may
require different types of multicoating. If JVS or any other repairman
buys a single vacuum depositing machine he can do single coating very
easily, but for multicoating he would need to determine what's right for
a particular lens and then run the lens elements through the machine
multiple times. Multicoating has anywhere from about 7 to as many as
21 layers, so it would require running in the macine that many times.
Lens factories, of course, have that many machines and just move a
batch of elements from one machine to another until the process is
completed. These machines are not cheap, nor are they small!!
Bob
Date: Thu, 15 Nov 2001
From: Kip Babington cbabing3@swbell.net>
Subject: Re: [Rollei] Planar lens design changes from 2.8E to 2.8F
To: rollei@mejac.palo-alto.ca.us
Jay -
I called JVS about a year or so ago to inquire, hypothetically, about
coating an uncoated Tessar in a Super Ikonta. He said his coating
services were aimed mainly at "repairing" (my word) front or rear lens
surfaces that had had the coating damaged. He charges $75 (or $150, I
can't remember) per surface, and that adds up so quickly that it wasn't
economically sensible to talk about doing a whole lens.
I'd give him a call and see if that's still his opinion - maybe things
have changed in his shop in the last year. But don't be surprised if it
proves to be cheaper to buy a newer, coated lens than to have your old
one coated in full.
Cheers,
Kip
Jay Kumarasamy wrote:
>
> Peter,
>
> I need to give Mr. Stelten a call. I have a pristine un-coated
> Summar, with faint fogging. I was thinking of getting it cleaned by
> JVS or DAG. Maybe I can get it coated, by JVS. It might cost
> quite a bit, but it might be worth it.
>
> - Jay
To: camera-fix@yahoogroups.com
From: Jim Brokaw jbrokaw@pacbell.net>
Date: Thu, 30 Aug 2001
Subject: Re: [camera-fix] Of screwthreads and pellix mirrors
Ron Schwarz at rs@clubvb.com wrote:
> you wrote:
>> Pellix mirror... I'm not sure, but possibly you can try and find a wrecked
>> Canon EOS RT, as these have pellix mirrors too. Or see if Canon still
>> stocks Pellix mirrors for this and the later EOS 1N RS.
>>
>> Or you can buy an EOS 1N RS and canibalize the pellix mirror...heh heh.
>
> Wouldn't Canon sell spare parts for an EOS?
>
> I believe Nikon had a very high speed version of the F or F2 that used the
> Canon pellicle, and I could swear that someone posted something somewhere
> in the past month or two about the company that Canon bought the pellicles
> from, I think it was an American company, who *may* still make them. I'll
> see what I can find out.
>
Isn't the pellicle mirror just a partially-silvered mirror? I'm not sure
what the % transmission v/s % reflectance is but it might be possible to get
glass of the same thickness and have it coated. At my last job, we used to
buy 'beam-splitter' glass for use in a sextant. This was ion (electron-beam)
coated with some kind of metallized finish, and was otherwise just plain
flat float glass, about 1/10" thickness. A sheet ~18" x 18" was about $50,
and you could get a *lot* of Pellix mirrors cut from a piece that size.
Perhaps someplace like Edmund Scientific sells this type of mirror glass. A
good web search will probably turn up someplace that could cut to size and
partial-mirror coat (for a price $$$).
--
Jim Brokaw
To: camera-fix@yahoogroups.com
From: Ron Schwarz rs@clubvb.com>
Date: Fri, 31 Aug 2001
Subject: Re: [camera-fix] Of screwthreads and pellix mirrors
>Isn't the pellicle mirror just a partially-silvered mirror? I'm not sure
>what the % transmission v/s % reflectance is but it might be possible to get
>glass of the same thickness and have it coated. At my last job, we used to
>buy 'beam-splitter' glass for use in a sextant. This was ion (electron-beam)
>coated with some kind of metallized finish, and was otherwise just plain
>flat float glass, about 1/10" thickness. A sheet ~18" x 18" was about $50,
>and you could get a *lot* of Pellix mirrors cut from a piece that size.
>Perhaps someplace like Edmund Scientific sells this type of mirror glass. A
>good web search will probably turn up someplace that could cut to size and
>partial-mirror coat (for a price $$$).
The pellicle was a thin piece of mylar (or similar) stretched taut across a
rectangular frame, with some sort of coating on one side. The term
(pellicle) predates photography, i.e., when you smoke jerky, one of the
stages is when the meat forms a pellicle on the outside.
I've got a *large* (relatively:)) beamsplitter with my front projector that
I used Way Back When in my studio days. (no idea where it is, of course,
after lo these many moves) I can only imagine what it would cost to
replace. It was a piece of optical glass, not particularly thin, with a
magic coating on one side, so that some of the projected light (aimed up)
would reflect out to the screen, while allowing some of the subject (and
screen image) to pass through to the camera.
I suspect that if you put something that was much thicker than the original
pellicle into a Pellix, you'd probably have to adjust the lensmount flange
distance. No idea how much or which direction.
From: jenspatricdahlen@hotmail.com>
To: rollei@mejac.palo-alto.ca.us
Subject: Re: [Rollei] Rollei tlr mirror replacement
Date: Thu, 24 Jan 2002
From: P Leeson
>Hi, a newer member here.
>I have an old Rolleicord with a severely de-silvered mirror and wondered f
>anyone here knows of a source for a replacement. I've been searching for
>front surface mirrors on the web and could try to cut one from a square one
>but a pre-made one would make my life a lot easier.
You can also have the mirror re-silvered! www.siriusoptics.com
/Patric
From: "Gene Johnson" genej2@home.com>
To: rollei@mejac.palo-alto.ca.us>
Subject: Re: [Rollei] Rollei tlr mirror replacement
Date: Thu, 24 Jan 2002
Phil,
I have some front silvered mirror I've salvaged from old Polaroids. I have
cut these for replacements before with very acceptable results. They are
slightly thinner than the originals, so a paper shim must be used. If you
don't come up with anything else for a reasonable price, let me know and
we'll work something out.
Gene
----- Original Message -----
From: P Leeson pjleeson@home.com>
To: rollei@mejac.palo-alto.ca.us>
Sent: Wednesday, January 23, 2002 6:38 PM
Subject: [Rollei] Rollei tlr mirror replacement
> Hi, a newer member here.
> I have an old Rolleicord with a severely de-silvered mirror and wondered if
> anyone here knows of a source for a replacement. I've been searching for
> front surface mirrors on the web and could try to cut one from a square one
> but a pre-made one would make my life a lot easier.
> THANKS
>
> Phil Leeson
>
To: camera-fix@yahoogroups.com>
From: "Rafael Alday" imaginafoto@iespana.es>
Date: Thu, 24 Jan 2002
Subject: Re: [camera-fix] TLR mirrors
Try at http://www.edmundoptics.com/
They have all kind of mirrors at not ver high prices
Rafael Alday
----- Original Message -----
From: P Leeson
To: camera-fix@yahoogroups.com
Sent: Thursday, January 24, 2002 1:27 PM
Subject: [camera-fix] TLR mirrors
Anyone have a source for tlr mirrors?
Old Rolleicord with severe desilvering.
Have found some Re-Silvering sites but was also looking for replacements
Thanks
To: camera-fix@yahoogroups.com>
From: "Mike Bergen" mike@creativedialog.com>
Date: Thu, 24 Jan 2002
Subject: RE: [camera-fix] TLR mirrors
I agree that a good original Polaroid SX-70 should not be destroyed for its
mirror. That is why I said "Polaroid SX-70 type cameras". However there is
another reason not to use an original SX-70, it is very difficult to get the
mirror out without hurting it or yourself (the mirror is glued in place, in
the cheaper models it slides out easily). I tried this on a badly damaged
SX-70.
While on the subject, Polaroid mirrors are not exactly the same thickness as
the Rollei mirrors and some focus adjustment (or shims) may be necessary.
Mirrors from old Kodak Instant cameras can also be used, however they are
even thicker as I recall. Each Kodak Instant camera has several mirrors
including a small half silvered mirror. These cameras are usually about $1
each, less by the truckload.
Mike
-----Original Message-----
From: Jim Brokaw [mailto:jbrokaw@pacbell.net]
Sent: Thursday, January 24, 2002 12:10 PM
To: camera-fix@yahoogroups.com
Subject: Re: [camera-fix] TLR mirrors
Mike Bergen at mike@creativedialog.com wrote:
> I use the first-surface mirrors out of old Polaroid SX-70 type cameras.
> They are a bit larger so they need to be cut to size. I get the Polaroids
> usually for about $5 at thrift stores, they must be the type in which you
> look through the lens.
> Hope this helps,
> Mike
>
> -----Original Message-----
> From: P Leeson [mailto:pjleeson@home.com]
> Sent: Thursday, January 24, 2002 4:27 AM
> To: camera-fix@yahoogroups.com
> Subject: [camera-fix] TLR mirrors
>
>
> Anyone have a source for tlr mirrors?
> Old Rolleicord with severe desilvering.
> Have found some Re-Silvering sites but was also looking for replacements
> Thanks
>
I have read (in Thomosy's books I think) that many of the Polaroid cameras
have a front-surface mirror inside, including the non-folding '600' series,
the ones that look like a lumpy plastic box. It seems a shame to dismantle
an SX-70 to take the mirror; that camera is one of the truly innovative
designs of the past few decades. Another source for front-surface mirror as
well as many things optical is Edmund Scientific Corp. They have a website I
think.
--
Jim Brokaw
To: camera-fix@yahoogroups.com
From: Frank Earl fbearl@yahoo.com>
Date: Thu, 24 Jan 2002
Subject: Re: [camera-fix] TLR mirrors
The short answer is NO! Especially yourself at home.
One chemical process involves suspending the clean
mirror in a solution of silver nitrate (involves
nitric acid) and a few other chems. When you add
another chem it precipitates the pure silver onto the
glass. (you can find the process somewhere in a
practical chem book, this is my best recollection).
You block the part you don't want silvered with a wax
resist or similar. There are companies that deal in
antique glass who will still do this for you. The fee
when I tried to get a pentaprism resilvered was about
$25 and I had to wait for the next batch to run. They
couldn't get it to work.
Another process they use for the mirrors in large
telescopes is to totally clean the glass, place it in
a vacuum chamber, heat aluminum until it vaporizes and
falls like rain on the glass surface.
Another process is a coating process they use for
hobbyists who grind their own telescope mirrors. You
grind the mirror, send it to the company, and they
coat it with a very thin "paint"-like material and
return it to you. They don't seem to sell the
material for DYI.
The best bet is to order the correct thickness of
front-surface mirror from Edmund. Take it to a glass
shop and have it cut for $2 and install it. If you
are worried about keeping the cameral original, put
the old mirror in an envelope, label it and keep it.
The mirror you get from Edmund's or from a Polaroid is
better quality. It is "silvered" with thin film
aluminum and won't tarnish in our lifetimes.
Good Luck
Frank
--- Martin Trucco martintrucco@tutopia.com> wrote:
> >Anyone have a source for tlr mirrors?
> >Old Rolleicord with severe desilvering.
> >Have found some Re-Silvering sites but was also
> looking for replacements
>
> Any easy way of resilvering/silvering? Or all the
> sites are commercial
> "resilverers"?
>
> Thanks
>
> Martin
>
Date: Fri, 25 Jan 2002
From: Michael Briggs MichaelBriggs@earthlink.net>
To: rollei@mejac.palo-alto.ca.us
Subject: [Rollei] RE: Rollei TLR mirror replacement
Phil Leeson asked:
> I have an old Rolleicord with a severely de-silvered mirror and wondered if
> anyone here knows of a source for a replacement. I've been searching for
> front surface mirrors on the web and could try to cut one from a square one
> but a pre-made one would make my life a lot easier.
Sometimes Surplus Shed, http://www.surplusshack.com/, or C and H Sales,
http://aaaim.com/CandH/index.htm, have front surface mirrors at surplus prices.
Maybe if you are lucky in the correct thickness.
--Michael
To: camera-fix@yahoogroups.com
From: Mr Mike Butler teamfcar@yahoo.com>
Date: Fri, 25 Jan 2002
Subject: [camera-fix] Re: TLR mirrors
Martin Wrote:
Any easy way of resilvering/silvering? Or all the
sites are commercial "resilverers"?
Martin,
If you know any Amateur Telescope Makers, a lot of
those guys silver there own mirrors. The address
below is one such person, pretty nice site.
http://lerch.yi.org/atm/Silver.htm
He seems to have spent a lot of time figuring it out.
Mike Butler
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, 28 Sep 2001
From: Dave Saalsaa SaalsD@cni-usa.com
Subject: Re: Harder coatings
Hi Roger,
With the advent of the Summicron M in 1969, Leica improved their
coatings to more durable types. The previous coatings of the 50's and
earlier as you are probably quite aware of were not the most abrasion
resistant especially when cleaned with old underwear and chewing tobacco
spit. ;-) Leica continued to increase the durability of the coatings to
this day with the latest version of lens coatings being the most
abrasion resistant. According to John Van Stelton of Focal Point, it is
not only the composition of the coating material but also the
temperature and method of application which determines the durabililty
of the coating. Leica improved their method of application greatly in
the late 60's and that is the main reason that we don't see the number
of cleaning marks on these later lenses that we do on the lenses from
the 40's and 50's.
Dave Saalsaa
>Since my only reference, Rogliati, pays little attention to coatings,
>does anyone have any information as to when or at what serial
>numbers Leitz began to use the modern much harder coatings?
>You know, those that Ted can rub the bejeepers on with his
>unmentionables without making the cleaning marks so often seen
>on the older glass.
>
>--
>Roger
From Leica Topica Mailing List:
Date: Fri, 28 Sep 2001
From: Dave Saalsaa SaalsD@cni-usa.com>
Subject: Re: Harder coatings
I think you're probably right, Roger. One other feature, which I
beleive may also factor into this, is the fact that Leitz was able to
make use of some newer optical glasses which also allowed for much
higher coating application temps which previously was not possible
because of the high failure rate of the older glass formulas. This also
from John Van Stelton at Focal Point. Failure rate due to thermal shock
of high temperature coatings accounted for an extremely high discard
rate until Leitz was able to come up with new optical glass formulas
which could withstand the application of high temperature coatings. This
probably accounted for some of increased durability of Leitz coatings of
later years.
Dave Saalsaa
From russian camera mailing list:
Date: Tue, 04 Dec 2001
From: Bob Shell bob@bobshell.com
Subject: Re: Cosmorex SE w/ Split Prism
> From: Blanka007@aol.com
> Date: Tue, 04 Dec 2001
> To: russiancamera@yahoogroups.com
> Subject: Re: Re: [russiancamera] Cosmorex SE w/ Split Prism
>
> I have two Zenit-16s, they are quite rare now, and both have it, very visible,
> almost to the point of being unusable. I know this camera had a lot of quirks,
> so I assumed this could be one of them.
My guess would be incomplete cleaning of the prisms prior to silvering.
If any of the lubricant from the polishing rouge is left on the surface
the silvering will not adhere completely and will flake off in time.
This was explained to me at the Canon factory in Shah Alam, Malaysia,
where they make most of the prisms for their SLR cameras. The inspection
process on finished prisms is surprisingly low tech. Young women with
good eyesight hold the prisms in the beam of light from a slide projector,
and rotate it around looking for flaws. I was surprised to see ordinary
Cabin projectors being used for this purpose!!
Bob
[Ed. note: caveat emptor - test first on non-critical bad and busted lens;
Bob Shell, noted former Shutterbug Editor and photobook author, has suggested
that there isn't any good solution (pun intended) for removing lens coatings,
and as noted, this one may loosen lens cement etc....]
From Leica Mailing List:
Date: Sun, 3 Mar 2002
From: "Dan Post" dpost@triad.rr.com
Subject: Re: [Leica] Removing lens coating
The stuff to use is good ole "Bon Ami"- which advertises that it hasn't
scratched yet!
It is recommended by Corning for cleaning glass, and their glass based
products- it is softer than the glass, and I have used it to remove crud
from many lens elements, lab ware, microscope slides, and even use it to cut
the wax and film build up on my auto windows-- Bon Ami, a rinse, and wiped
down with newspaper makes the glass sparkle- and it hasn't scratched yet!
Not as sweet smelling as toothpaste, but it is reliable!
Dan
- ----- Original Message -----
From: Dr.Alexander.Kraus@gmx.de
To: leica-users@mejac.palo-alto.ca.us
Sent: Sunday, March 03, 2002
Subject: Re: [Leica] Removing lens coating
> > Thanks Don
> > But I'm talking about a cheap lens.
> > He charges about 100 per surface and grinds some
> > glass away. I just want to strip the coating away and use it like that.
> > Javier
>
> Javier,
> no solvent will be able to dissolve magnesium fluoride (which is actually
> very good). I had good success removing older coatings with toothpaste in the
> past. You have to rub a little bit until it comes off, but it doesn't seem to
> harm the glass.
>
> Regards,
> Alex
>
> --
> GMX - Die Kommunikationsplattform im Internet.
> http://www.gmx.net
From camera fix mailing list:
Date: Fri, 5 Apr 2002
From: "Kelvin" kelvinlee@pacific.net.sg
Subject: Fw: Custom Optical Coatings from the Experts at Edmund Optics
FYI, those of you looking into re-coating.
----- Original Message -----
Originator: Edmund@em10.net
We've got Ion Beam Assisted coatings to make sure our coatings get an A+ for
coating durability and stability. And we can design and apply custom coatings
up to 130 layers - so we can handle any assignment you give us. E-mail
sales@edmundoptics.com or http://zzz1.net/rd/rd.asp?ZXU=845&ZXD;=86085
visit our website for more information!
Our Coating Selection Includes:
Visible Broadband AntiReflection
Near-Infrared Broadband AntiReflection
Extended Broadband AntiReflection
V and 2V Narrowband AntiReflection
Single Layer MgF2
Broadband High Reflectance
Narrowband High Reflectance (Notch Filter)
Dielectric High Reflectance
Aluminum Coatings
Silver and Gold
Dielectric Laser Mirror
Dual Laser Line Mirror
Hot and Cold Mirrors
Broadband Visible Beamsplitter
NIR & Telecom Non-Polarizing Beamsplitter
Non-Polarizing Coatings
Brewster Plate Polarizing
Broadband and Laser Line Cube Polarizers
High Efficiency Telecom Polarizing Filters
Long Wave and Short Wave Pass
Bandpass
http://zzz1.net/rd/rd.asp?ZXU=845&ZXD;=86085 read more about our coating capabilities!
If you would like to continue receiving information from us you do not need
to respond to this email.
However, if you would NOT like to receive these messages, please unsubscribe
by http://em10.net/UM/CMF.asp?A33.402.86085 clicking here.
Edmund Industrial Optics has been a leading supplier of optics and optical components to industry since
1942, designing and manufacturing a wide array of multi-element lenses, lens coatings, imaging systems,
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Visit http://zzz1.net/rd/rd.asp?ZXU=846&ZXD;=86085 www.edmundoptics.com to learn more
Date: Fri, 05 Apr 2002
From: "stuey63au" madfamily@bigpond.com
Subject: Re: Fw: Custom Optical Coatings from the Experts at Edmund Optics
Or for those in Australia:
Longman Optical
Ian Mansfield
Technopark Centre, Dowsing Point
Glenorchy Tasmania 7010
Ph. 03 6233 5505
45 years in business, camera lenses repolished, doublets recemented,
coated with MgF, aluminising of mirrors, with silicon monoxide
overcoating, collimation.
Cheers
Mark