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Mac Hayes
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 24, 2004 - 02:49 am: | 
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I recently picked up some Pentax Spotmatics on eBay, two of which had the F1.4 50mm lenses. Both these lenses are decidedly amber, noticeable both through the viewfinder and when just looking through them off the camera. None of my other non-SMC screwmount lenses have this 'feature.' Is this an aging effect, or did they come from the factory that way? |
Berk Sirman
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 24, 2004 - 05:51 am: |
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It is the aging effect on some 50/1.4 Takumars and some 35/2.0's I believe. A radioactive element, torium, was used in coating the glass (I believe) and this turns yellow with age. I do not think there is anything to do about it. You can use the yellowed lenses in B/W work and some colow work where a warming filter may be needed. You may pick up another 50/1.4 that does not have the yellowing for other color work. I have a Super-Multi-Coated Takumar 50/1.4 that does not show yellowing at all. Yours is Super-Takumar not Super-Multi-Coated Takumar or SMC Takumar I believe, right?
Do some research about this online, you will get plenty of info.
If you hate the yellowed lens completely, you may give it to me:-) |
Howard
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 24, 2004 - 07:53 am: |
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Hi Mac,
I'm not sure exactly where, but if I remember correctly there is a thread in the archives on this site about treating this condition with sunlight.
Good luck with it. I don't think it was in the coating, but the fact that these lens used rare earth glass in the lens elements.
Howard |
Zygmunt Roslon
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 24, 2004 - 07:56 am: |
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Mac.You got one of the best ever lense produced on a planet . Have myself plenty of Pentaxes from 70 s and found the pictures they make are better than blueish new Pentax ones... Zygi |
Henry
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 24, 2004 - 08:09 am: |
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Basically, you wrap the lens in aluminum foil. Wrapped up like a baked potato. That is all but the front element. Then set it on a window sill pointed towards the sun. You want as much of the sunlight to shine into the lens as possible. Let "bake" for several days and the yellow should be gone.
When I say bake I'm mostly joking. I've done this a couple times and the lens doesn't really get that warm. It would get much warmer without the aluminum foil.
Henry |
Mac Hayes
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 28, 2004 - 04:33 am: |
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Thanks for the comments, guys. Birk, these *are* Super Takumars, not SMC. I will try the sun-baked treatment and let you know what happens - if the sun ever comes out again. I have already taken some test shots with one of them and didn't find the tint even noticeable with color print film. They are so sharp I am not ready to give them away just yet. |
Mac Hayes
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 28, 2004 - 04:36 am: |
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Sorry, slip of the finger, I meand "Berk" not "Birk." That "i" in your last name threw me off... |
nihraguk
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 28, 2004 - 07:45 am: |
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Hi, I have a yellowed SMC 50/1.4 Tak as well, and I was wondering: what if I get a UV bulb and place the lens under it? Would it have the same effect, and is this advisable? Have reservations about leaving the lens on the windowsill, where dust/fungal spores can collect and where the errant little sister might knock it over. |
