I will try to remove a lot of old fungus in my Carl Zeiss Jena Sonnar 1:2 f=5cm for Contax.
The front lens was in a really shape and there only little to do, but the back lens group turn out to be really good, much better than I expected to be.
I first try with some lighter fluid, but it could not remove the fungus, then I try with Hydrogen Peroxide 3% and then the magic happen, all the fungus simply is gone away.
I had a big problem when I try to unscrew the front name ring, because there was a little set screw that was glued with a strong glue, so I simply drill it out the set screw with a 0,9mm drill bit
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