Radioactive lenses - Oak Ridge Web site

Discussion in '35mm Cameras' started by Nicholas O. Lindan, May 19, 2004.

    1. Advertisements

  1. Nicholas O. Lindan

    Neil Gould Guest

    Neil Gould, May 19, 2004
    1. Advertisements

  2. Nicholas O. Lindan

    Lewis Lang Guest

    Subject: Radioactive lenses - Oak Ridge Web site

    The Oak Ridge Boys are radioactive?

    No wonder they don't sound so good on television anymore... ;-)
    Lewis Lang, May 20, 2004
  3. Nicholas O. Lindan

    Bandicoot Guest

    There was a thing on the wireless a few days ago about the craze for patent
    medicines based on Radium around the time of its discovery - mostly to
    stimulate the endocrine system and 'improve' sexual 'performance'. Amazing

    The funniest bit was from a guy at Oak Ridge who collected mementoes of this
    sort of thing, and had an empty box (so the contents were presumably used)
    of Radium suppositories...

    Bandicoot, May 20, 2004
  4. They have the eye-watering details elsewhere on the same site:

    "All Home Product customer orders were shipped in a plain wrapper for

    Richard Williams, May 20, 2004
  5. Nicholas O. Lindan

    Lewis Lang Guest

    Subject: Re: Radioactive lenses - Oak Ridge Web site
    "The end is near... and its glowing too!" ;-).
    Lewis Lang, May 20, 2004
  6. Nicholas O. Lindan

    Lewis Lang Guest

    Subject: Re: Radioactive lenses - Oak Ridge Web site

    Sounds like Viagra for the incredible Hulk ;-).
    Lewis Lang, May 20, 2004
  7. Nicholas O. Lindan

    Norman Worth Guest

    It's interesting that this does not mention the earlier lenses that
    contained thorium. I understand that Th has been used in optics at least
    since the 30s, and the AeroEktars (late 40s and early 50s) are famous for
    it. External radiation is almost entirely from gamma rays emitted by the
    daughter products of thorium decay. From the top of my head and looking at
    the formulation given, it would seem that there is significant
    self-absorption of gamma radiation in the lens itself. I wonder if that was
    taken into account in calculating the dose rates. In any case, the
    regulations have the force of law. I doubt if anyone has been harmed by
    normal use of these products.
    Norman Worth, May 21, 2004
  8. Nicholas O. Lindan

    Bandicoot Guest

    LOL - "Don't make me randy, you wouldn't like me when I'm randy..."

    Bandicoot, May 21, 2004
  9. Nicholas O. Lindan

    Lewis Lang Guest

    Subject: Re: Radioactive lenses - Oak Ridge Web site
    Randy and Paula and Ryan are fine - its Simon Cowell (spelling?) you have to
    worry about ;-)
    Lewis Lang, May 22, 2004
  10. Is this possibly the reason why some older lenses are revered over their current
    counteparts in that the hazmats they used to produce them then cannot be used
    steven.sawyer, May 22, 2004
  11. Nicholas O. Lindan

    Karl Winkler Guest

    Karl Winkler, May 23, 2004
  12. Nicholas O. Lindan

    Bob Monaghan Guest

    Karl, you might want to be careful about promoting that site, since it may
    encourage readers to destroy or discard their yellowed takumar lenses,
    when there may be a simple and non-destructive cure for their problems,

    A number of users have reported being able to bleach out the yellow
    discoloration of those pentax lenses by strong sunlight/uv - see gene
    poon's posting (on "Sunlight vs. Yellow Peril: IT WORKS!") on my lens
    faults pages at pages for details,
    quoting viz.:

    From camera fix mailing list:
    Date: Tue, 08 Apr 2003
    From: "Gene Poon"
    Subject: Sunlight vs. Yellow Peril: IT WORKS!

    I just posted the following to the Spotmatic group. Perhaps some
    members on camera-fix will find it useful:

    About the experiment to see if sunlight would bleach Yellow Peril, the
    radiation-caused yellowing of internal elements afflicting the
    7-element 50/1.4 Super Takumar, Super-Multi-Coated TAKUMAR and SMC
    TAKUMAR lenses for the Pentax Spotmatic cameras:


    It has only been since Thursday, April 3 that I put two 50/1.4
    Takumars on the windowsill. Since then, every day except Saturday has
    been at least mostly sunny here in Northern California. Today I got a
    bit impatient, and besides, I had to go into the box containing my
    Pentax M42 stuff anyway, so I figured I may as well find out what was
    happening and get out the rest of the 7-element 1.4 lenses to start on
    them, if the sun bleaching was actually proceeding.

    The experimental subjects were my very yellowest Super-Takumar and a
    Super-Multi-Coated TAKUMAR which was moderately yellowed and had
    filter ring damage and slightly stiff focusing. I figured I should
    experiment with the two worst lenses, in case something bad happened.
    The UNCAPPED lenses got completely wrapped in aluminum foil except
    for the rear element, to reduce heat buildup in the sun, and also
    because doing so would reflect light back through the lens, hopefully
    attacking the yellowing from both sides.

    This morning, after only five days, I unwrapped the lenses, and
    compared the two experimental subjects with the rest of my 50/1.4
    Takumars. THE SUN BLEACHING WORKS! The two experimental lenses are
    now the least yellow (the comparison is not even close) of all my
    50/1.4 Takumars except for the very early, 8-element Super Takumar
    that is not prone to yellowing. Compared to that lens, and to the
    55/1.8 and 55/2.0 lenses which also are not prone to yellowing, there
    is still a slight tinge of yellow, about the same as the pink tone
    from a weak skylight filter. They are being rewrapped for another stay
    in the sun, and the rest of my yellow Takumars are going to join the
    first two on the windowsill in a few minutes.

    Probably many Pentax M42 collectors and users will have Takumars on
    their windowsills, very soon if not already!

    -Gene Poon
    Bob Monaghan, May 23, 2004
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.