I have a Fed NKVD (serial 76777), with the following lens problem. The rear optics consist of two elements cemented (glued) together. This glue is separating, causing som kind of blur and spider web like cracks. It took a long time to search a repair method, but I found one. I'm planning to separate both elements, using solvents. And reglueing them with canada balsam (which is used for microscope preparations). When I succeed, i'll let you know if you are interested. I'm testing this on an old broken I-22 now, but the two lenses won't yet separate.
Well... I have to say this topic is more than 5 years old now. But I recently fixed the lens, recementing the elements with canada balsem.
It was a hard job. I had to 'open' a seam first before I could carfully take out the two rear elements out of their brass fitting. I heated the lens in the oven on 180 degrees, and after a while it gently came loose. I re-cemented it after removing the old resin and ultrasonic cleaning of the lens parts.
It's a very hard job... I know one guy in France working on glasses He is used to unglue and re-cement lenses He can also polish glasses, but you will loose the coatings. It is not really cheap, so it's better to choose high value lenses...
Fed Lens repair
Posted - Feb 16 2010 : 1:38:17 PM
