Canon LTM Yellowed Canon 50mm f1.4 -- light loss?

Canon M39 M39 screw mount bodies/lenses
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pagpow

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Has anybody estimated the light loss that comes with a yellowed 50 1.4? I'm trying to figure out whether my light meter reads too high in low light or its angle picks up too much background light or the yellowing is costing me a noticeable portion of an f stop. Any experience out there?

Any advice about keeping it yellowed for its B&W shooting properties outside or giving it the sun cure the web talks about to eliminate the yellowing?

Thanks.
 
I had no idea they would yellow - are you sure ? Coating on the Canons
is orange/yellow anyway.

(I have two).

Roland.
 
Unless I am misreading or misremembering -- both possible -- that Canon had thorium or other radioactive lens element that, over the passage of time provides a nice light yellow. This is especially so with long-term dark storage. Some people like it for shooting B&W film w/o a yellow filter and some people indicate it can be reversed by exposure to sun. Now that you've reaised the issue. I'll go check it again.

I take it you haven't seen any such effect with yours?
 
pagpow said:
Unless I am misreading or misremembering -- both possible -- that Canon had thorium or other radioactive lens element that, over the passage of time provides a nice light yellow. This is especially so with long-term dark storage. Some people like it for shooting B&W film w/o a yellow filter and some people indicate it can be reversed by exposure to sun. Now that you've reaised the issue. I'll go check it again.

I take it you haven't seen any such effect with yours?
Click to expand...

No, pagpow, mine have not yellowed.

I know the effect from other lenses (like a Zuiko 55/1.2 that I once had),
they definitely looked yellow, even threw a yellow shaddow on white paper
in the sun. The consensus there was to leave it on a window sill for a while
and the lens will get bleached.

Can anybody else confirm that some 50/1.4 lenses included
radioactive elements ? I need a Geiger counter :)

Thanks,

Roland.
 
If you're near Boston, MA, feel free to stop by and use my Geiger counter. This is how I found out that the RE GN Topcor 50/1.4 is radioactive -- hotter than radioactive Summicron.
 
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