Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,548   Posts: 1,544,575   Online: 968
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. #1

    Join Date
    Aug 2006
    Shooter
    35mm
    Posts
    174

    Hey! My Takumar actually IS yellow...

    I'd heard rumors before that Super Takumars (or maybe it was just the 50/1.4?) go yellow sometimes with age, but I always thought the rumor was just a product of people being confused by seeing a yellow lens coating rather than a purple one.

    But, in the wake of my last 50/1.4 being stolen last spring, I've just got a new one, and looking through it it looks like I've got a yellow filter on the front.

    So how's that going to effect my photography? Like a yellow filter? Including having to factor in the filter factor, I suppose, as I haven't got a TTL on any of my m42s? Anyone know what exactly causes this little phenomenon?

  2. #2
    TheFlyingCamera's Avatar
    Join Date
    May 2005
    Location
    Washington DC
    Shooter
    Large Format
    Posts
    8,363
    Blog Entries
    51
    Images
    436
    I believe it is radiation from a thorium element in the lens that turns it yellow. I also believe you can effect a (relatively) short-term "cure" by putting the lens in direct sunlight for several days. Over time the yellow would come back, because of continuous radioactive decay of the thorium in the glass.

    If my memory is correct and this is indeed the source of the yellow color, just don't sleep with the lens between your thighs or you'll have funny-looking children. Otherwise the radioactive output is weak enough your desk drawer or closet door or whatever else you keep between you and the lens is enough to block the radiation.

  3. #3
    Lee L's Avatar
    Join Date
    Nov 2004
    Shooter
    Multi Format
    Posts
    3,244
    Can't vouch for the degree of accuracy here, it's the internet after all:

    http://www.pentax-manuals.com/repairs/yellow.htm

    Lee

  4. #4
    Trond's Avatar
    Join Date
    Jul 2004
    Location
    Harestua, Norway
    Shooter
    Multi Format
    Posts
    661
    Images
    74
    I used a strong UV lightsource on both my 35mm 2.0 and 50mm 1.4 Super-Takumars. The yellow color was gone after one day´s treatment. This was at least two years ago, and the lenses still look good to my eye.

    Trond

  5. #5
    Michel Hardy-Vallée's Avatar
    Join Date
    Apr 2005
    Location
    Montréal (QC)
    Shooter
    Multi Format
    Posts
    4,351
    Images
    132
    I had some yellowing on a SMC takumar 50mm f1.4, and what I did was to wrap it in aluminium foil, uncovering only one side of the lens, and leaving it on a windowsill for a few days. Somewhere I've read that the foil supposedly bounced the UV rays back, thus accelerating the cure, but who knows. At any rate the yellowing was gone after a few days.
    Using film since before it was hip.


    "One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11

    My APUG Portfolio

  6. #6

    Join Date
    May 2003
    Location
    Valley Stream, NY
    Shooter
    Multi Format
    Posts
    3,216
    Yeah, mine is too. I use it only for B&W anyway, so I didn't bother with the sunlight treatment. Rough guesstimate say that it knocks about 1/3 to 1/2 stop worth of the light passing through it.

  7. #7
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,270
    Images
    148
    Luckily mines in a new home, it fell out of my backpack halfway up the Glyders 18 years ago. (Welsh mountains)

    Ian

  8. #8

    Join Date
    Jun 2003
    Location
    Nova Scotia
    Posts
    923
    Quote Originally Posted by Ian Grant View Post
    Luckily mines in a new home, it fell out of my backpack halfway up the Glyders 18 years ago. (Welsh mountains)

    Ian
    Not necessarily Ian-you may have lost a magnificent lens with a built in yellow filter. Among my lenses is a 35 f2 which is one of the sharpest 35's I've ever used,
    Mark
    Mark Layne
    Nova Scotia
    and Barbados

  9. #9
    DBP
    DBP is offline

    Join Date
    Mar 2006
    Location
    Alexandria, VA
    Shooter
    Multi Format
    Posts
    1,883
    Images
    34
    Quote Originally Posted by TheFlyingCamera View Post
    I believe it is radiation from a thorium element in the lens that turns it yellow. I also believe you can effect a (relatively) short-term "cure" by putting the lens in direct sunlight for several days. Over time the yellow would come back, because of continuous radioactive decay of the thorium in the glass.

    If my memory is correct and this is indeed the source of the yellow color, just don't sleep with the lens between your thighs or you'll have funny-looking children. Otherwise the radioactive output is weak enough your desk drawer or closet door or whatever else you keep between you and the lens is enough to block the radiation.
    Or funnier looking children, whichever the case may be.

    Some of the FSU lenses have the same issue, supposedly because of lanthanum. I would think that if shooting black and white the 'problem' may be worth retaining for contrast.

  10. #10
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,270
    Images
    148
    my Chinon f1.4 50mm lens that only recently replaced it is far better anyway.

    Actually I had a great pair of Chinon's and an f1.4 lens until they were stolen and I went back to Pentax equipment

    Quote Originally Posted by Mark Layne View Post
    Not necessarily Ian-you may have lost a magnificent lens with a built in yellow filter. Among my lenses is a 35 f2 which is one of the sharpest 35's I've ever used,
    Mark

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin