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07-15-2015, 08:59 AM   #16
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Ok... now I'm just curious about that lens... Is the lens itself the mystery, or whether it has thoriated elements? If the lens is the mystery, perhaps someone can identify it.

07-15-2015, 03:56 PM   #17
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Turtle sunning itself at the lake. ISO 100, F8, Super Takumar 50mm f/1.4 7-element radioactive.



Taken today.
07-16-2015, 01:35 AM   #18
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QuoteOriginally posted by Auzzie-Phoenix Quote
Ok... now I'm just curious about that lens... Is the lens itself the mystery, or whether it has thoriated elements? If the lens is the mystery, perhaps someone can identify it.
I already post a thread about my mysterious lens : https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/295176-unkn...5mm-2-8-a.html
it's yellowish seems to be caused by thoriated elements @_@ it's an unknown lens so I have no other info
07-16-2015, 01:38 AM   #19
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Know anyone with a geiger counter? lol. Then you'd know for sure.

08-20-2015, 01:22 PM - 1 Like   #20
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Another from SMC Takumar 50mm 1.4

08-21-2015, 11:03 PM   #21
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Well, you certainly don't seem to have any problems achieving critical focus with that 50mm super tak. Everything I've seen you post is crisp and sharp.
08-22-2015, 01:00 AM - 1 Like   #22
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In camera b&w processing K20D. Book sharing with great grand mother.

Super Takumar 55 1.8

08-22-2015, 02:26 AM   #23
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K20D Super Takumar 55 1.8
08-22-2015, 03:01 AM   #24
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These are great photos and the lens could lead to a bonus, these lenses could fuel a nuclear reactor one day.

See the photo of thorium lenses, a Tak is on the left.


https://en.wikipedia.org/wiki/Thorium
08-24-2015, 12:56 AM   #25
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QuoteOriginally posted by Auzzie-Phoenix Quote
Well, you certainly don't seem to have any problems achieving critical focus with that 50mm super tak. Everything I've seen you post is crisp and sharp.
thankss, the focus peaking on the K3 helps a lot ^^
09-22-2015, 11:24 PM   #26
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A swarm of insects around sunset, taken with the super takumar 50mm f/1.4 7-element radioactive.
09-23-2015, 01:32 AM   #27
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I've just added the 50mm/1.4 to my Takumar collection, and it's my first Tak to have some yellowing. My other radioactive Taks are clear.

So here's the question: to de-yellow or not to de-yellow? Should I think of the yellowing as an intrinsic part of the character of the lens after its 40 year life and leave it as it is? Or am I entitled to put it under a UV lamp and return it to the same clarity it had on the day it was made?

I'd be interested to hear everyone's opinions about this. My own gut feeling is that I want to de-yellow the lens and use it as a day-to-day shooter. But in doing that will I be destroying an essential part of what makes it such a classic lens?
09-23-2015, 03:35 AM   #28
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QuoteOriginally posted by Dartmoor Dave Quote
I've just added the 50mm/1.4 to my Takumar collection, and it's my first Tak to have some yellowing. My other radioactive Taks are clear.

So here's the question: to de-yellow or not to de-yellow? Should I think of the yellowing as an intrinsic part of the character of the lens after its 40 year life and leave it as it is? Or am I entitled to put it under a UV lamp and return it to the same clarity it had on the day it was made?

I'd be interested to hear everyone's opinions about this. My own gut feeling is that I want to de-yellow the lens and use it as a day-to-day shooter. But in doing that will I be destroying an essential part of what makes it such a classic lens?
I have a yellowed sup tak and a clear smc tak as well as K,M,and A 50 1.4s . The yellowed sup tak is easily my favourite. It seems to have far more character but maybe I am just fooled by the warmer images it creates. I will be interested in other peoples experiences here.
09-23-2015, 01:45 PM   #29
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I de-yellowed mine as much as possible. I can't get it 100% clear though as the LED lights I have aren't powerful enough for the job, and in PA sunshine isn't exactly something we get enough of for proper de-yellowing. I don't think of the yellowing as "character", per se. The actual optical elements, plus any scratches, dust, etc.... would be the character. Plus the yellowing will just come back over time anyway.
09-23-2015, 02:45 PM   #30
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Thanks for the input, GUB and Auzzie-Phoenix. I've decided to do a sort of staged de-yellowing. At the moment the lens is so yellowed that I get almost a brown colour cast that needs heavy correction in post-processing. So I've put it under a full spectrum LED in the hope of bringing it down to a more subtle level of yellowness. Hopefully I'll be able to keep some yellowness when it adds a pleasant warmth to shots, but get rid of it completely in post-processing when I want a neutral colour rendering.

And I guess if I decide that I want the yellowing back then it's just a matter of waiting another 40 years.
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