M42 50mm SMC Takumar f/1.4 Yellowed - Light Source Suggestions?

Discussion in '35mm Cameras and Accessories' started by zenrhino, Sep 1, 2012.

  1. zenrhino

    zenrhino Member

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    Hi,

    I have a yellowed SMC Takumar in M42 for my Spotmatic. I love the lens for b/w, but I want to shoot color with it and I find the yellowing drops probably a full half-stop from getting through the viewfinder (which at my age is increasingly a problem).

    I could just set it out in the sun as such: http://www.apug.org/forums/archive/index.php/t-41848.html

    But, is there a better/faster way to get UV on it?

    Thanks,

    Clint
     
  2. Steve Smith

    Steve Smith Subscriber

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    I can't think of a bigger or brighter UV source.


    Steve.
     
  3. Chrismat

    Chrismat Subscriber

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    I've read blogs where people have used a black light. They put the black light and the lens in a shoebox. I used the sun method myself for my Takumar 1.4, but make sure you wrap the lens body in aluminum foil. If not, the black exterior of the lens is going to absorb a lot of heat possibly loosening the lens elements.

    Chris
     
  4. Gerald C Koch

    Gerald C Koch Member

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    With the yellowing of the lens element what you will see will be a slight warming of colors. People will tolerate any color shift provided it is toward a warm color. I would try the lens with at least one roll of color slide film and determine whether you like the colors. Putting the lens in the sun can cause lubricants to migrate to the lens elements. Once this happens the lens must be disassembled and cleaned.
     
  5. brucemuir

    brucemuir Member

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    Dont feel bad Zen…I have a 35 1.4 Nikkor in the same condition. The only part that bugs me is the light loss (that cant be proper grammar)

    I haven't gotten around to trying a fix…the sun is only good during certain seasons around here.
     
  6. ignatiu5

    ignatiu5 Subscriber

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    I've used the sun before for M42 Pentax lenses, but I recently wanted to speed up the process for a yellowed SMC Takumar 6x7 lens. I tried the UV lamp in my biosafety cell culture cabinet for hours and hours. I tried the UV of a DNA crosslinker box, again for hours times multiple sessions. Neither was as effective as the window ledge wrapped in aluminum foil. Go figure.
     
  7. rdtaylor_sea

    rdtaylor_sea Member

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    I bought a UV-A reptile light at Petco. Cleared up a yellowed radioactive LTM Summicron 50 in about 10 days.
     
  8. RidingWaves

    RidingWaves Member

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    Bruce, its possible to remove the cells from the 35 1.4. I cleared one of mine and kept one yellowed, looks nice in B&W. The one I cleared took at least 2 weeks, all day, but it was in the winter, put the lens on a old busted body and wrapped with foil.
     
  9. polyglot

    polyglot Member

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    Sun is the cheapest option; for faster you need a UV lamp bright enough that it's a hazard to humans, e.g. a medical-sterilisation tube.
     
  10. jochen

    jochen Member

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    Hello,
    I have cured 2 SMC 1,4/50 Takumars under an OSRAM Vitalux 300 W lamp in a distance of about 20 cm (about 8''). I think this is similar to what is described above as UV-A reptile lamp. It took about 2-3 days. The lens was wrapped in aluminium foil an I put a metal sheet with a roud opening for the rear lens over it, but nevertheless it got about 60° C warm. I neither had lens separation nor problems with migrating lubricant. Not only the UV irradiation but also heat causes the bleaching, but you have to be careful not to to melt the lens cement. Besides the radioactive lens (contains Thorium, an alpha-emitter) is in the rear element (affirmed by a Geiger counter), so put this towards the light source. I put a little mirror under the front lens (without filter!), so the light is reflected and can work two times. I want to warn to do the same with the 1:2/35 mm Takumar since this lens will suffer lens separation in the rear element by the resulting heat (the glas types seem to have different thermal expansion)!
    Some weeks ago I have read that a LED lamp from the international furniture house IKEA (the name was JANSJÖ) was successfully used for this and had success in less than one day! So I assume that every strong LED lamp (MAGLITE; LED lenser; CREE LED) could do the same job without producing so much heat like a UV-A reptile lamp and does not need so much electrical energy, only a set of batteries.
     
  11. benjiboy

    benjiboy Subscriber

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    Last edited by a moderator: Sep 3, 2012
  12. Chrismat

    Chrismat Subscriber

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    This last post is great, I'm definitely going to keep that in mind in case I get another yellowed lens or the Takumar 1.4 I have no yellows again. Thanks benjiboy!

    Chris

    http://www.flickr.com/photos/chrismat61/
     
  13. benjiboy

    benjiboy Subscriber

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    These lenses go yellow because they contain Thorium salts and are mildly radioactive so might consider also getting some lead lined boxer shorts too :D
     
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  15. rdtaylor_sea

    rdtaylor_sea Member

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    The UV-A reptile lamp I mentioned a couple posts ago doesn't produce much heat at all. It's not a heat lamp. I had the lens under the lamp for ten days and it never got warm to the touch. It only cost me $9.00 and completely cleared the lens.
     
  16. Uncle Bill

    Uncle Bill Subscriber

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    I got two lenses a M-42 50 f1.4 and an early 35 F2 FD lens that need the UV treatment, the desk lamp looks to be the most effective solution. I got too much shade around my house.
     
  17. benjiboy

    benjiboy Subscriber

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    The Ikea Jansjo lamp's neck is so flexible Bill I was able to put the head almost touching the rear element of my FD 35mm f2 lens that I placed on a small mirror to maximize the effect, and it worked like a charm, in fact every time I look at the lens now I can't believe it, I shot some Fuji Provia with it to test it and I projected it and can see no colour caste at all.
    Interestingly my eldest son who's a nuclear physicist told me that the yellow caste will eventually come back, but not in my lifetime :D
     
  18. benjiboy

    benjiboy Subscriber

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  19. Uncle Bill

    Uncle Bill Subscriber

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    I'm stopping by Ikea on the way home to pick one of those lamps up this afternoon.
     
  20. benjiboy

    benjiboy Subscriber

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    Please let me know if it works for you Bill.
     
  21. 2bits

    2bits Subscriber

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    benjiboy,
    Thanks for the great tip! I'm getting one right away.
    2bits
     
  22. benjiboy

    benjiboy Subscriber

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    I'm going to ask Ikea to pay me a kickback, maybe they could advertise the lamps as being particularly suitable for this purpose :smile:
     
  23. fenderslash

    fenderslash Member

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    I was keen to try this out so I went and bought a cheap no-name brand LED desk lamp from Woolworths, similar in style to the Ikea lamp that people have been posting about above, and tried it out on a significantly yellowed Takumar S-M-C 35mm f2 lens. I put the lens front element down on to a compact mirror and shone the LED lamp through the rear element from above. The results? I checked it ten hours later after just leaving it overnight and the improvement was amazing. Right now it's at the two and a half day mark and I don't think there's been much improvement since my initital check, but it's still early days. Maybe that last bit of yellow is hard to kill. I'll continue to leave it under the lamp and see what happens over the coming days.
     
  24. PentaxBronica

    PentaxBronica Member

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    I can confirm that the Ikea lamp works. Mine took about four days exposure to clear completely, I used an old CDR as a mirror underneath the lens to reflect the light back into the lens (and just in case the lens turned out to focus it well enough to scorch the desk!)
     
  25. GarageBoy

    GarageBoy Member

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    Does the yellowing warm or cool images? I always assumed since it was yellow, it would pass more blue
     
  26. benjiboy

    benjiboy Subscriber

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    It warms the image on colour film, on monochrome film it has the same effect as a pale yellow filter.