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Blue_agave
Tinkerer
Username: Blue_agave
Post Number: 1
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 13, 2007 - 09:51 pm: | 
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We're talking about a Mamiya TLR lens here. The viewing lens had some lens separation on an internal, and required cleaning, and believe it or not, as I was disassembling it, the two glued elements literally fell apart. Surprisingly, the glue must have been Balsam, because it was a bit sticky and cleaned off readily with acetone.
Now the barrel mounting arrangement for this doublet is snug, and it is tightened into place with a ring - IOW, I could just put the elements, un-joined, into the barrel, tighten down, and I'd have a lens with bit more reflection, a bit less contrast, and maybe a teensy bit of wonkiness because of the lack of the thickness of a glue bond.
Or, I could get some UV-cure optical adhesive and re-glue the lenses. Obviously, re-gluing would be best, but it also will cost for the glue, and the time, and there's something grimly permanent about using glue.
Remember - it's just the viewing lens, so standards are way more relaxed than if I were attempting the same thing with the taking lens.
What does everyone think - should I go to the trouble of gluing, or not? |
Markus
Tinkerer
Username: Markus
Post Number: 17
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 13, 2007 - 11:01 pm: |
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Canada balsam is pretty hard to find these days. I ended up buying some from a guy from Canada on ebay to re-cement a lens element. With balsam the repair is reversible and more old school. The balsam was not all that expensive (I think about $15 incl. shipping for 20ml) and after using two drops of it I now have a lot more than a lifetime supply. It also smells pretty nice.
If you want to give the Canada balsam a try, I can mail you some. You really only need a few drops. Send me an email to markus.berndt at gmail dot com with your address if you are interested.
- Markus |
Blue_agave
Tinkerer
Username: Blue_agave
Post Number: 2
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 14, 2007 - 12:42 am: |
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Sounds like a plan, Markus - thanks! I'll drop you a note. You know, I was wondering about that eBay balsam - I wrote the guy to ask him a little about it, but did not get a reply. But if you got good, crystal clear results, then I'm sure willing to give it a try (especially on the cheap).
How do you use the eBay stuff - right out of the bottle? And how do you cure it?
Thanks again and I'll drop you a note. If balsam is reversible, and if I can get a bit easily, I guess attempting a glue job makes more sense than leaving the elements un-joined. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 225
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 14, 2007 - 03:07 am: |
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I can highly recommend Kremer Pigmente http://kremer-pigmente.com/ as an excellent source for Canada balsam. I have recememented three lenses by now and all of them show excellent results. For those who are not really familiar with recementing lenses, read this first http://www.atmsite.org/contrib/Sapp/LensGlue/
It is however not so easy to get first class results (dust, air bubbles, too much or not enough glue) and the whole affair can turn out to be a nasty mess in the end with glue all over your workbench, good preparation can help prevent this. |
Markus
Tinkerer
Username: Markus
Post Number: 18
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 14, 2007 - 06:19 am: |
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The Canada balsam I bought from that guy on ebay worked well. The lens is clear and I managed to get it together without making too much of a mess. The trick is not to use too much of it, a little more than one drop of it was enough for a lens with a diameter of less than 2cm. Here is another helpful link courtesy of google books: http://www.google.com/url?sa=t&ct=res&cd=10&url=http%3A%2F%2Fbooks.google.com%2F books%3Fid%3DFVYGuuNYF6QC%26pg%3DPA45%26lpg%3DPA45%26dq%3Dcanada%2Bbalsam%2Blens %26source%3Dweb%26ots%3DNH0mQuliXl%26sig%3Dav7rGg-RgirB6u0a79HbHlDEu14&ei=ZIFiR7 7JGaCqigGM25j4Dg&usg=AFQjCNH6zWJjhlEM3tlWq3LQgUlEOEKtjA&sig2=zyYPI-agkU3vRY7dMhD XyQ
I will mail you some Canada balsam this weekend. |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 85
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, December 16, 2007 - 04:06 am: |
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Balsam is very commonly used in Histology labs to mount tissue samples under a cover slip. If there is a lab in your area, ask em and they will probably be glad to give you a few CCs of it. Bring your own bottle. |
Blue_agave
Tinkerer
Username: Blue_agave
Post Number: 6
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 20, 2007 - 05:10 am: |
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In case anyone is following along, Markus, as good as his word, mailed me a syringe of Canada balsam. I have already repaired the 250mm lens (3 drops), and I've repaired a 135mm rear element (1 drop). I will say that if I had not enjoyed the advantage of a snug barrel and tightening ring for both repairs, I would most definitely have required some sort of jig, like machinist V blocks or the like, to position and hold the lenses. But if you've got a cooperative barrel and ring, this is really almost fun. (It would surely be fun if the hovel where I live were not so remarkably dusty.)
Actually, the most difficult aspect of the repair was getting the cap off the syringe. Markus warned me about that.
Now, some purists may roll eyes and moan that it is possible that the glued elements are not centered with precision - but remember, these are viewing lens repairs on TLR equipment, and they simply do not require ultra-precision. Having said that, Markus pointed me to some photographs he has taken with his repaired lens, and they are tack-sharp, and certainly do not appear to be suffering any deleterious effects from his repair.
Anyway, I'm uncharacteristically happy, and not a little amazed that everything worked out.
Thanks Markus! |
Markus
Tinkerer
Username: Markus
Post Number: 20
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 20, 2007 - 11:16 am: |
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I am glad to hear the repairs worked out for you! You're most certainly welcome.
I second your statement about the difficulty in centering the lenses. The one that I repaired also was sitting in a barrel without any play so there was no problem in getting it centered.
Repairing/cleaning a shutter is one thing, but actually repairing a lens made very fond of that particular camera!
- Markus |
Realityguy
Tinkerer
Username: Realityguy
Post Number: 4
Registered: 12-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 21, 2007 - 08:48 am: |
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I have a large format 90mm angolon that the front element has separated into the large front lens and smaller rear one..Apparently by this thread..not a good idea to "self-fix"..Anybody have an idea of the cost and where to have it done(and have you had it done yourself?)?I have a couple other wide angle 90ms(angolon and carl meyer) so it's not all that important to repair that one,just might be nice to have a spare front element..just in case. |
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