Lens element glue
Levistarks
I remember reading a post about not getting a lens too warm, because you might
melt the balsam? that holds the individual elements together.
Well last weekend I bought some old lenses at an estate sale. none were fully
functional. All were cheap. anyway I decided to start on the worst one first.
It was a goerz double anastigmat 7" I say was, as the shutter which was what
I believe is called a compound type , and proved to be well beyond repair. the
Twin shutter leafs were both broken at the base where they should pivot.
anyway that wasn't the worst of it. the Lense had a lot of seperation Small
reticulations I will call them all across one of the interior surfaces. Both
front and rear elements.
So I decided what the heck, It's worthless anyway I might as well try to get
the thing apart. So out came the heat gun, It didn't take much heat to get the
lens out of it's mount. But quite a bit to loosen up the "glue" that holds the
elements in place. One is completely (all three elements) apart, and they
cleaned up nicely with a little laquer thinner. I think I'm going to try
boiling water on the next one, as it might be a little safer. Ok just on the
off chance that I wanted to put them back together what do the current Lense
makers use? The stuff between them smelled like pine tar. Is this what is
still used? where would I find it? yeah sure I know, on a pine tree. My first
inclination is to use some "slow" thick super glue. (after insuring that the
lens surfaces were absolutely clean), and I would try to find a dust free area
to work in. Obviously I would have a little more trouble getting them apart the
next time.
I have an old turner reich tripple convertable which is my primary lens. It had
a little seperation around the edge when I bought it (front element) hasn't
changed any since, but maybe someday I'll need to "fix" it also. I know that
If you've read this entire post, by now you think I'm a nut. But hey aren't
most L.F. people a little eccentric?
thanks for any help you might be able to give me.
Levi in St Louis.
Richard Knoppow
levis...@aol.com (Levistarks) wrote:
Gentle heat will separate lenses glued with Canada balsam. The usual
method is to heat the elements on a hot plate but dipping them in warm
to hot water will work. The water doesn't have to be boiling. In fact
boiling water may crack the elements.
Lenses can be re-cemented with balsam but there were several grades
and the setting depends on the thickness and solvent. Liquid balsam is
available from Tri-S Sciences in Burbank CA. After the cells are
cleaned very carefully a drop of balsam is put on the concave side and
the lenses very gently massaged together with a circular motion until
the balsam is uniformly spread out and there are no bubbles. The
assembly should then be kept in an oven at about 150F for a couple of
days to cure. The lens mounting can be used to insure centering of the
elements. (Assuming they were centered correctly when manufactured).
Modern optics are cemented with synthetic adhesives which are cured
with ultra-violet light. Similar to the stuff dentists use for
fillings now. The cement is readily available from Edmund Scientific
but the light sources are very expensive, around $500 US for the
cheapest. Balsam is good for practicing with in any case since it can
be easily removed and the cementing done over again.
Lenses which show just a small ring of separation along the edge
should be left alone. Slight edge separation does not affect
performance except with the lens wide open.
---
Richard Knoppow
Los Angeles, Ca.
dick...@ix.netcom.com
Arne Croell
Levistarks wrote:
The original lens cement was most probably Canada balsam (from balsam
firs). It may still be sold, but nowadays synthetic materials are used
for these purposes. Most of them are cured by the action of UV light, so
that it is possible to align lenses under yellow light and then harden
them with UV. You can get them at Edmund Scientific
(http://www.edsci.com/). Dont use conventional glues, they are probably
not clear, and will not give you optical quality. Without optical
instrumentation it is nearly impossible to get the lens elements
properly centered, but given the present condition of the lens as you
described it, it may be fun trying anyway. For the Turner-Reich I would
try to find a repair shop capable of proper centering the elements.
Arne Croell
Scott Dorsey
In article <19971211065...@ladder02.news.aol.com> levis...@aol.com (Levistarks) writes:
>So I decided what the heck, It's worthless anyway I might as well try to get
>the thing apart. So out came the heat gun, It didn't take much heat to get the
>lens out of it's mount. But quite a bit to loosen up the "glue" that holds the
>elements in place. One is completely (all three elements) apart, and they
>cleaned up nicely with a little laquer thinner. I think I'm going to try
>boiling water on the next one, as it might be a little safer. Ok just on the
>off chance that I wanted to put them back together what do the current Lense
>makers use? The stuff between them smelled like pine tar. Is this what is
>still used? where would I find it? yeah sure I know, on a pine tree. My first
>inclination is to use some "slow" thick super glue. (after insuring that the
>lens surfaces were absolutely clean), and I would try to find a dust free area
>to work in. Obviously I would have a little more trouble getting them apart the
>next time.
The stuff in there is Canada Balsam, which is available from Edmund
Scientific in NJ. More modern lenses use UV-setting epoxies, which are
also available from Edmund.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Richard Davis
Richard Knoppow wrote:
> Modern optics are cemented with synthetic adhesives which are cured
> with ultra-violet light. Similar to the stuff dentists use for
> fillings now. The cement is readily available from Edmund Scientific
> but the light sources are very expensive, around $500 US for the
> cheapest. Balsam is good for practicing with in any case since it can
> be easily removed and the cementing done over again.
>
Dentists found they were getting cataracts from UV exposure, so there
are a lot of these UV sources available on the used market. You can
pick a used one up at a dental supply store for much less. And be
extremely careful because the cataract danger is real.
Jean-David Beyer
My dentist has a "paddle" about 3/8 inch thick of an amber color (sort
of like a 0C safelight filter in color) that he (or his technician) place
between their eyes and the light source (which is inside my mouth anyway).
I close my eyes when it is on. I assume my eyelids filter out most of
the uV light.
--
Jean-David Beyer
Shrewsbury, New Jersey
Jay Wenner
Jean-David Beyer (jdb...@exit109.com) wrote:
: My dentist has a "paddle" about 3/8 inch thick of an amber color (sort
: of like a 0C safelight filter in color) that he (or his technician) place
: between their eyes and the light source (which is inside my mouth anyway).
: I close my eyes when it is on. I assume my eyelids filter out most of
: the uV light.
I've worked over UV tables, and it took me a while to learn. After
wearing goggles, I looked like Rocky Raccoon. Then I used a face shield,
long sleeve shirt and gloves. I ended up with a sunburned neck and
wrists.
Anyway, if you need UV light, the question is how strong? Most
university biochemistry depts have UV transilluminators (tables) for
viewing gels. It would seem pretty easy to talk your way into leaving a
lens on a (cleaned) table for a 15-30 min. (I say cleaned because the
dyes used in gels like to bind to DNA, so they're mutagens.) Many labs
also have hand held UV light sources.
Jay Wenner
Gregory Blank
In article <19971211065...@ladder02.news.aol.com>,
levis...@aol.com (Levistarks) wrote:
Is this what is
> still used? where would I find it? yeah sure I know, on a pine tree. My first
> inclination is to use some "slow" thick super glue. (after insuring that the
> lens surfaces were absolutely clean), and I would try to find a dust free area
> to work in. Obviously I would have a little more trouble getting them
apart the
> next time.
Try Edmund Scientific's website, you can locate them with the search
engines commonly found on the web. Request thier optics catalog they have
your glue.
Best Always Greg
Jean-David Beyer
chips. Perhaps there still are; I have not done any hardware work in some time.
To erase them, they were put under a uV light for a while. So an eeprom
eraser would probably work, too, if you have some computer hardware types
in your circle of acquaintance.
Bill Harris
Subject: "Re: Lens element glue: UV Source"
Jean-David Beyer <jdb...@exit109.com> writes (in part):
>There used to be EEPROMs (erasable electronically programmable read only memory)
>chips. Perhaps there still are; I have not done any hardware work in some time.
>To erase them, they were put under a uV light for a while. So an eeprom
>eraser would probably work, too, if you have some computer hardware types
>in your circle of acquaintance.
There still are; the current Mouser Electronics catalog lists a EEPROM
eraser for ~$40 (four chips). Mouser is at http://www.mouser.com/ or
(800) 346-6873.
I wonder if ordinary sunlight has enough UV in it to work?
Bill Harris
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skgrimes
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--All types of rings, adapters, flanges, etc
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----
>
> I wonder if ordinary sunlight has enough UV in it to work?
>
> Bill Harris
>
Although I use a U.V. lamp in actual practice I have tried sunlight to cure
this UV cement and it works fine.Takes all day here in the Northeast but
this could be a real advantage to photographers in the SouthWest. And, you
end up with an all natural result, contact with the Solar System, etc. SKG
Charlie
Bill Harris wrote:
> I wonder if ordinary sunlight has enough UV in it to work?
I've been thinking the same thing. Might have to leave it in the Sun
for several hours. Outside would be best. I believe ordinary glass
knocks out some of the UV.
--
Charlie Newark, DE
To reply by email please remove antispam "TY" from address.
Scott Dorsey
In article <66t9i0$g...@camel12.mindspring.com> NOSPAM....@mindspring.com writes:
>Subject: "Re: Lens element glue: UV Source"
>Jean-David Beyer <jdb...@exit109.com> writes (in part):
>
>>There used to be EEPROMs (erasable electronically programmable read only memory)
>>chips. Perhaps there still are; I have not done any hardware work in some time.
>>To erase them, they were put under a uV light for a while. So an eeprom
>>eraser would probably work, too, if you have some computer hardware types
>>in your circle of acquaintance.
>
>There still are; the current Mouser Electronics catalog lists a EEPROM
>eraser for ~$40 (four chips). Mouser is at http://www.mouser.com/ or
>(800) 346-6873.
No, you guys are thinking of EPROMS. EEPROMS are Electrically Erasable,
which is what that extra E is for.
Anyway, the Mouser EPROM eraser has two germicidal lamps of about 2W
each, and will work nicely as a handy little UV source.
>I wonder if ordinary sunlight has enough UV in it to work?
Yes, but it will take a day or so to set. It's a real pain. And you
ought to have a short wave UV source around the house anyway, because
it's handy for all kinds of stuff.
Bill Harris
Subject: "Re: Lens element glue: UV Source"
>No, you guys are thinking of EPROMS. EEPROMS are Electrically Erasable,
>which is what that extra E is for.
>Anyway, the Mouser EPROM eraser has two germicidal lamps of about 2W
>each, and will work nicely as a handy little UV source.
Dang, did I stick an extra "E" in there? <s>
--Bill
Bill Harris
Subject: "Re: Lens element glue: UV Source"
>Although I use a U.V. lamp in actual practice I have tried sunlight to cure
>this UV cement and it works fine.Takes all day here in the Northeast but
>this could be a real advantage to photographers in the SouthWest. And, you
>end up with an all natural result, contact with the Solar System, etc. SKG
I imagine that if one recements lenses on a very irregular basis, the
"solar powered" UV lamp might be cost-effective.
But as Scott Dorsey notes, everyone needs a UV lamp around the house.
Paul M. Anton
Wouldn't a sun lamp work? If they still sell them that is.
Cheers:
Paul Anton
Scott Dorsey
In article <670kro$a...@sjx-ixn2.ix.netcom.com> "Paul M. Anton" <xx...@xxxx.xx> writes:
>Wouldn't a sun lamp work? If they still sell them that is.
Old fashioned sunlamps are still available, but they are mostly IR, without
any real short wave UV. You can't get a tan off of them.
However, your local tanning salon might let you put a lens on their bed....
Bob Mueller
Scott Dorsey wrote:
>
> In article <670kro$a...@sjx-ixn2.ix.netcom.com> "Paul M. Anton" <xx...@xxxx.xx> writes:
> >Wouldn't a sun lamp work? If they still sell them that is.
>
> Old fashioned sunlamps are still available, but they are mostly IR, without
> any real short wave UV. You can't get a tan off of them.
Is "real short wave UV" really what is needed? I don't think it even
goes far through glass, but the near UV does better in penetration, so
it can reach the glue through the lens.
The fluorescent kind of UV lamp makes a moderate amount of near UV,
enough so I can cure Plexiglas cement in a fairly short time. In the
Edmund list of products, the Summers Laboratories adhesive is explicitly
stated to be cured by 355 nm to 365 nm, which is not "real short". With
luck an old tanning lamp can be found at a flea market for a few
dollars; look for the kind with fluorescent tubes and not the kind with
a small, high-pressure mercury vapor tube. The latter let out a lot of
the eye-damaging kind of very short wavelength radiation, and often make
all that IR for which you have no need.
Bob
Richard Knoppow
Bob Mueller <r.mu...@kfa-juelich.de> wrote:
The entry in the Edmund catalogue for Summers Laboratories
adhesives specifies long-wave UV with a wavelength of 355nm to 365nm.
It refers to a flourescent source. The cheapest source listed in this
catalogue is the "Bond Wand" at something like $600 US.
I called Edmund about sources and was told that sunlight would not
work and that black-light sources using a mercury lamp would also not
work. No mention of "Gro-Lites" etc. The bonding lamps indicate
curing times of a few minutes.
The adhesive is cheap ($20/oz!) enough to get some to experiment
with. If some readily avaiable and cheap light source works it would
be great, even if it isn't fast. It would still be better than the
three or four days of baking that Canada Balsam needs.
Steve Grimes has posted that he has had some luck with sunlight and
I would rather believe the voice of experience than some telephone
order taker at Edmund.
Arne Croell
A good description of how to glue lens elements can be found in:
Hank H. Karow: Fabrication methods for precision optics.
Wiley-Interscience, New York 1993.
It is expensive (123$ list price), so buying probably does not make
sense, but a library should be able to get it. The part on cementing
lenses can be found on pages 551-563.
In this article he states that for for fixing the lenses with UV-curing
cement a short exposure to longwave "black light" UV (no wavelength
specified) is enough, and that full curing takes about an hour in a UV
light box. The recommended solvent for removing the UV cement is
acetone.
Hope this helps.
Arne Croell
Richard Knoppow
Arne Croell <ar...@sgi3.krist.uni-freiburg.de> wrote:
Thanks for posting this. The only other books I've seen on actual
lens manufacture are Brittish books published in the mid 1930's and
early 50's. The methods described in them are probably no longer
current practice.
Scott Dorsey
In article <349459...@kfa-juelich.de> r.mu...@kfa-juelich.de writes:
>Scott Dorsey wrote:
>>
>> In article <670kro$a...@sjx-ixn2.ix.netcom.com> "Paul M. Anton" <xx...@xxxx.xx> writes:
>> >Wouldn't a sun lamp work? If they still sell them that is.
>>
>> Old fashioned sunlamps are still available, but they are mostly IR, without
>> any real short wave UV. You can't get a tan off of them.
>
>Is "real short wave UV" really what is needed? I don't think it even
>goes far through glass, but the near UV does better in penetration, so
>it can reach the glue through the lens.
> The fluorescent kind of UV lamp makes a moderate amount of near UV,
>enough so I can cure Plexiglas cement in a fairly short time. In the
>Edmund list of products, the Summers Laboratories adhesive is explicitly
>stated to be cured by 355 nm to 365 nm, which is not "real short". With
>luck an old tanning lamp can be found at a flea market for a few
>dollars; look for the kind with fluorescent tubes and not the kind with
>a small, high-pressure mercury vapor tube. The latter let out a lot of
>the eye-damaging kind of very short wavelength radiation, and often make
>all that IR for which you have no need.
Hmm.... at that long a wavelength you might even be able to get away with
a blacklight bulb. $2.50 at your local head shop, though not terribly
high intensity.