Lens Asahi Super-Takamar

[lucien]

lolz and lolz,
and what would my 1/2 life be a mere 1,000,000 yrs : ) btw that name might be copyrighted better make sure

 

[Roboticspro]

Get two of them and place them 48.75mm apart to achieve sustained critical mass...helps to stay warm in the winter. On the serious side, I have this lens and the Canon FD 35mm f2 (V1 Concave) which has a thorium front element. No worries with the alpha emission; the workers that handled the glass grinding operations were in harm's way though. I used a single Philips UV fluorescent tube in an enclosure to rid the yellowing, which took about a week (~150-170 hours) with no grease running in the lenses. That tube also kills any fungi present found in many "vintage eBay" lenses...;-).

 

[Lawrence A.]

My SMC Takumar is sitting on a mirror in the sun in the window clearing up the yellowing. I had my doubts the UV in plain old sunshine would work, but it was quite yellow when I started this project and is almost clear now. The UV at 5000 ft. of elevation probably helps, the same UV that has my dermatologist freezing of dozens of pre-cancers every time I go, although most of the sun damage to my skin was done growing up at sea level in Boston. Anyway, I recommend a zinc sunscreen for your skin and a good sunny window for your yellowing thorium glass. I sat the lens on a mirror to maximize the UV it got, and turned it occasionally. I also cooled it now and again lest the glue holding the lens elements melt. It seemed unlikely, but it didn't hurt to be safe. I nice lens. I'm looking forward to test driving it without the yellow which, in the absence of a custom white balance, left a noticeable cast.

 

[lucien]

thanks for the info. Some good tips there. I think I'll leave mine as is. I haven't even shot with it yet. Will the yellowing return overtime? What camera body do you have it mounted on

 

[Lawrence A.]

I'm using mine on a Pen-F for fun (I have other 50's and the terrific little m. Zuiko 45mm f1.8), but I hope to acquire a Sony a7 and use legacy glass on it for a while, mostly Olympus OM lenses, but this too, and a couple of Leica thread mounts.