on 12/3/03 8:56 PM, ClassicVW@xxxxxxx at ClassicVW@xxxxxxx wrote:
> Hello all...
> I picked this up from an ebay auction's description of the 55mm f/1.2 lens...
>
> "Here's the caveat? This lens is famous for an element that gradually yellows.
> The result is a ³weak tea² coloration. The tint is strong enough to render the
> lens unsuitable for color-transparency film (Kodachrome, Fujichrome), but
> there's no problem with or color- or B&W-negative materials."
>
> Having just acquired one of these myself in an auction, (yes, it was mis-id'd
> as a 50mm in the auction), I'm curious if this "famous yellowing element"
> statement has any basis in fact? The last sentence kills me too- The yellowing
> element renders the lens unsuitable for color transparency, but it is OK for
> color negative film use ??!!
>
> Thanks!
> George S.
Its all true. Some believe that the yellow coloring is due to 'rare earth'
or radioactive additives in the optical glass. The list went around on this
a while back. My 55/1.2 isn't yellow, but a recently picked up Pentax 50/1.4
Super Takumar is - there is a famous website telling of a sure cure for
it... The early 50/1.4 Super-Takumar is famous for this yellowing.
I'd rather try a different fix that went around on my camera-fix list a
while back. Supposedly, some have had good results by 'bleaching' out the
yellow by setting the lens in direct sunlight for a couple weeks... the
theory is that the sunlight's UV and/or heat buildup reverses the
'radioactive' yellowing... Whether this is true or not I don't know, nor do
I know if its physically (in the notion of Physics) possible for this to
work.
I do know that you can relatively easily correct color casts when printing
color negative, compared to correcting color casts in transparency
projection. Of course, scanning a transparency makes correcting the color
easy.
--
Jim Brokaw
OM-'s of all sorts, and no OM-oney...
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