Treating a Thorium-Tinted Takumar 50mm Lens

Takumar 50mm 1.4 in foil

Let’s take a quick trip back to my old lenses, shall we? I have been playing with them quite a bit lately. The M42-EOS adapter with a confirm chip has helped keep my focus on point and made a big difference in how this one-eyed photographer shoots with them. My favorite lens has been the Super-Takumar 50mm f/1.4. It has proven to be tack sharp (once properly focused) while giving a nice vintage vibe that I’m not getting from my modern lenses.

The Super-Takumar 50mm f1.4 has an interesting history. My particular copy is from 1971 or earlier but, given the provenance, I’m guessing no later than 1968. This is a lens my father used while on active duty following the Pueblo Incident. The fun part of this lens is that it yellows with age. Thorium was used on the rear lens element. It is radioactive and, as it decays, effects the glass. The more I used the lens, the more I argued the wisdom of trying the easy, home-remedy to clear the yellow tint. Part of me liked the yellowing which, in my mind, mimics the yellowing of old photographs. But if this lens is this much fun yellow, what can I do with it clear?

I followed the general instructions online: Expose the lens to UV light to make the yellow tint go away. Wrapping it in aluminum foil, I placed it in the back yard to suck up the brilliant, Oklahoma sun. The foil served two purposes. First, it helps prevent the black lens from getting overly hot. Second, it helps the sunlight reflect back through the lens, hopefully helping “bake” the yellow a little faster. The important part is to have the aperture wide open and be patient.

On that note, it is time to be patient. The lens is in place and I’m checking it on occasion to make sure it is getting good light. Initial results seem to be promising. More news when the lens is finished baking!



Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.