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06-19-2020, 02:17 PM   #1
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Element oranging

I down loaded an article or thread and of course did not get the authors name. Anyhow the title was MANUAL FOCUS LENSES and spoke of all Pentax manual focus lenses, a very helpful article. In the discussion about the Takumar 50mm 1.4 and the Takumar 55mm 1.8 (all M42s) the author wrote that the lenses suffered "element oranging". My question is what is element oranging and how do you determine if your lens glass is oranging? and does this really make a lot of difference when using the lens or does it effect picture quality? I shoot mostly outside landscapes and natural things ponds, animals, etc., very few portrait work except birthdays of course.

thanks dipo 1

06-19-2020, 02:30 PM   #2
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QuoteOriginally posted by dipo 1 Quote
I down loaded an article or thread and of course did not get the authors name. Anyhow the title was MANUAL FOCUS LENSES and spoke of all Pentax manual focus lenses, a very helpful article. In the discussion about the Takumar 50mm 1.4 and the Takumar 55mm 1.8 (all M42s) the author wrote that the lenses suffered "element oranging". My question is what is element oranging and how do you determine if your lens glass is oranging? and does this really make a lot of difference when using the lens or does it effect picture quality? I shoot mostly outside landscapes and natural things ponds, animals, etc., very few portrait work except birthdays of course.

thanks dipo 1

It's due to slight radioactivity of rear thorium element which over time turns the cement yellow. Easily removable with UV either from sun (slower) or UV lamp (faster).

Or find an 8 element super takumar which doesn't have thorium oxide element.
06-19-2020, 02:35 PM   #3
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These lenses (and some others of that era) used glass that contain radioactive Thorium oxide. Over the years, the radiation inside the lens tends to turn the glass a pale orangish-amber. It could affect color balance somewhat but not sharpness.

The coloration can be reduced by exposing the lens to UV light. UV doesn't reduce the radiation (the lens will turn amber afters some additional years) but it clears the color cast for a while.

It's easy to spot a lens with this issue -- just hold the lens in front of a well-lit white piece of paper. If the paper looks somewhat amber or orange through the lens, it has the issue.
06-19-2020, 02:41 PM   #4
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Here's old thread discussing the de-yellowing, in case you are interested.


Takumar yellowing question - PentaxForums.com


If you use auto white balance, or set the white balance manually, maybe that can counteract the effects of a yellowed lens.


Nice thing is you have a built in yellow filter to be used for B/W photography

06-19-2020, 02:42 PM   #5
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Because you are not doing much portrait work, you would probably be happier with a clear lens. As zvon says the 8 elements don't yellow and I feel the SMC yellows to a lesser extent. But I couldn't perceive any loss of sharpness from the yellowing and chose to not go ahead with any bleaching. So should I bleach my 50s - PentaxForums.com
06-20-2020, 02:21 PM - 1 Like   #6
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I have a 50mm f/1.4 lens that has this very characteristic. Automatic white balance will often do the job, but there are times (say, sunsets) where you don't want to let AWB rob you of the rich colors. In some of those cases you would be better off with a set WB, and the slight yellowing would be harmless. As chance would have it, I just a few moments ago did an experiment with the lens on my K5. I took five shots: AWB, Daylight, 4800K, 4400K and 4000K. The Daylight WB is, of course, too yellow. To my eyes, somewhere between the 4400K and 4000K seems as though the WB would match the AWB result. These shots were taken around 5:00 PM, so the light was a little yellower than it would be earlier in the day, but somewhere around 4200K looks as though it would be a good setting to mimic Daylight with a non-yellowed lens.
06-20-2020, 03:13 PM   #7
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Many years agoI bought a spotless S-M-C Takumar 50/1,4 that had yellowed over the years. I think I paid $10/ One week on a south facing windowsill cleared the yellow and I still have the lens - one of my fav’s.

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