Radioacive element in my Canon FD 35 f2 lens

[Uncle Bill]

I bought my brother's Canon F-1n yesterday along with a couple of lenses, one of them being a '70s vintage 35 f2 which I guess went head to head with the legendary Nikkor O 35 f2 lens.

Small challenge, one of the elements yellowed, did Canon use any rare earth glass like Pentax did with their 50 f1.4 and can the same UV exposure trick get rid of the yellow? I shoot black and white about 80% of the time but I would prefer a more colour neutral glass.

[Mustafa Umut Sarac]

I have had a Leitz Summitar 5cm and when you look from the outside , it had a brown tint. But it took my lifes most neutral , highest quality pictures. So deciding from outside is not a good idea.
Get your lens , get your 35 mm film and put your lenses front element on your film strip for few minutes , if there is no burn at your film , there is no radioactive glass.
Buy a piece of aluminum foil , wrap the back element , and put your front element directed to the sun , if you can find the bright sun at this winter. After 48 hours , if there is radioactive yellow tint , it would be turned to neutral. Summitar have a proven high ratio thorium inside and back element made by lead crystals to prevent burn.

Good luck , if it is radioactive , it is rare and excellent.

Umut

[hpulley]

The original Canon FD 35mm f/2.0 SSC with a concave front element indeed has a thorium element. Most people put it in the sun for a while to bleach it out. I leave mine yellow since I like the effect in B&W as a subtle yellow filter, often enhanced with a #8 filter.

Absolutely excellent optics! Sharp, sharp sharp! I can blow up pictures made with that lens and the detail is incredible.

[hpulley]

Oh and here is a comparison of the warmth, can't remember what film this was, E200 or Kodak Gold probably with 35mm f/2 thorium and a normal 28mm f/2:


TRAIN35 by Harry Pulley, on Flickr


TRAIN28 by Harry Pulley, on Flickr

[benjiboy]

I have one of these lenses and it's a stunning performer, it was an " L " lens before Canon ever thought of the term, it seems to defy the laws of physics because at all apertures its as sharp at the edges as it is in the middle, this is a legendary lens too.
They did use rare earth glass Uncle Bill like the Pentax 50mm f1.4 until the Japanese Government prevented optical companys using this glass because of health and safety issues of the workers grinding it.
I have done a lot of research to find out if there is any danger from owning a Thorium lens, and so has one of my sons who is a physicist on my behalf, and as far as we can tell there's extremely little, only a tiny fraction of the radiation level that is permissible for workers in the nuclear industry.

[hpulley]

35mm f2 thorium 2 by Harry Pulley, on Flickr


FD 35mm f2 thorium 1 by Harry Pulley, on Flickr

[benjiboy]

My example of this lens Harry is an older chrome nosed version that that was made in November 1971 that isn't marked S.S.C. so it isn't multi- coated, I had mine CLA'd a few months ago because the lens cost me very little and I thought the expense on such a good optic was justified, I even managed to find the original BW 55A hood, it now looks and works like a new one and is my best lens and probably my most used one.

[hpulley]

Yes, mine is the II version though Canon didn't mark version on the lens back then. As you say, the original version had a chrome nose.

I've never had a lens CLA'd though my 28mm f/2's aperture doesn't stop down reliably so I may need to look into it. Just tough when the lenses are so cheap on the used market these days, the labor costs of repair and maintenance seem quite high by comparison.

[benjiboy]

The CLA probably cost about £75 probably less that than I could have bought a second hand one for, and I now know that it's reliable and in first class condition, I generally prefer having the equipment I have maintained if possible.

[Uncle Bill]

I'm going to try out this lens on Friday with my F-1n with some Legacy Pro 400 and see what I get. The lens I have is the early chrome nose FD version.