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Voigtlander Heliar 75/2.5 milky cement
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PostPosted: Fri Feb 08, 2019 12:13 pm    Post subject: Voigtlander Heliar 75/2.5 milky cement Reply with quote

I know this is not a "real" Heliar, but I digress.

I bought one of these lenses for $150 in M-mount knowing that it had some milkiness inside. I thought it was just something I could clean off (I have a lens spanner..) but it turns out the milkiness is in the cement in the 4th group (the cemented achromat).

It doesn't seem to have a terrible effect on image quality, but I'm wondering if it's worth it to decement and recement that doublet. This is a modern lens so am not sure if it still uses canada balsam or some UV epoxy.

PostPosted: Fri Feb 15, 2019 11:19 pm    Post subject: Reply with quote

Almost certainly UV epoxy. Apparently soaking in methyl ethyl ketone can dissolve it. The fumes of MEK can also destroy your liver (fatally) in short order -- be very careful about where and ventilation.

But might be worth seeing if you can buy the group as a replacement part.