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Dennis Walstrom
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 09:22 am: | 
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I purchased a Topcon Super DM with 50 and 200 mm lenses. The 200 was a "junker" with lens separation in the front group of two elements (due to being dropped). I have been able to disassemble, remove, and clean the elements. My task now is to find someone that can direct me to purchasing a very small amount of Canada Balsam to re-cement these elements. Any ideas where a person would get a couple drops of this stuff? Or any other ideas would be appreciated. Thank you... |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 12:16 pm: |
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Canada balsam is used in microscopy, for embedding small particles on glass carriers. Maybe a (biological) lab supply could help you. |
Jon Goodman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 12:28 pm: |
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Another option is UV cured optical quality watchmaker's cement. You can buy it here:
www.slarose.com
This cement is clear as water, and it stays liquid until exposed to UV rays for a certain period of time.
Jon |
David Nebenzahl
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 01:26 pm: |
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My understanding is that pretty much nobody uses Canada balsam anymore; the UV-cured cement is much easier to use, and gives better results with less chance of bubbles.
I'm no expert on this, but there is an expert on this, and a lot of other optical stuff, who posts on some of the Usenet newsgroups (in particular, rec.photo.large-format). His name is Richard Knoppow. You might try there. You could either post a message there, or better yet, search that newsgroup (Google's archives let you do this) for this subject, which has come up a number of times there. I believe I've seen complete instructions for recementing lens elements there. |
David Nebenzahl
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 01:34 pm: |
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I'm sorry, I gave the wrong name for that newsgroup: it's rec.photo.equipment.large-format. (There's also a r.p.e.35mm group which I think Richard K. also frequents.) |
Charles Ewen
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 08:30 pm: |
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You can get Canada Balsam from Post Apple Scientific:
http://www.postapplescientific.com/
Richard Knoppow has recommended Summers Optical's UV-cured cements in the past:
http://www.emsdiasum.com/Summers/optical/cements/products.html
The Summers site has a good how-to article on cementing technique. |
Steve Roberts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 09, 2005 - 02:48 am: |
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Hi,
I did this job on the four element colour correction filter of a video camera recently using a Loctite UV-curing optically clear adhesive. Can't remember the Loctite product details, but results were excellent.
Steve |
Reiner
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 09, 2005 - 04:01 am: |
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I have once successfully re-cemented a separated lens using clear car paint. Propably you know these small bottles of car paint with a brush inside to do quick repairs of small dings. They buy in automotive shops and super markets. I had one available in clear when I was searching a lens cement and jut used it. I shaked it well before which resulted in a lot of air bubbles in the paint. I placed a small drop of paint on the surface of one lens and placed the other lens on top of it. The upper lens swam like on an oil film and it was tricky to keep it on top. I kept it in position with two toothpicks. During that time all air bubbles disappeared without any additional care. Very soon (app. 30 sec.) the paint became more like honey and then thicker and thicker. I tried to align the two lenses as good as it is possible without a special tool. When it was hardened I placed it carefully on the radiator and left it for a week.
After that I removed the superficous paint from the sides with a screw driver blade and renewed the matt black paint at the sides of the lenses. After reassembly the complete lens was totally clear and looked as out of the factory. I took very good slides with it. However I am qiute shure that the alignment of the two parts is not perfect. But this issue independant of the glue anyway. |
Roman Dubravsky
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 10, 2005 - 03:11 am: |
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I'm using for lens repair synthetic acrylic "canadian balsam", which is used in optical industry. I have big can (one kilogram) of it, I can send small bottle to you. |
Mike Kovacs
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 10, 2005 - 10:17 am: |
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The advantage of Canada Balsam is that it can be heated and reseparated if you get the element centering wrong. If I were to recement a lens, I would also consider Canada Balsam. |
Roman Dubravsky
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 11, 2005 - 07:33 am: |
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Acrylic cement is possible to melt by xylen. |
