does anyone know which specific models of the 55mm 1.8 takumar are radioactive?

Discussion in 'Adapted Lenses' started by colbycheese, Jul 14, 2015.

  1. colbycheese

    colbycheese Mu-43 Veteran

    May 1, 2012
    Way up there.
    I am still consdering getting a 55mm 1.8 takumar but i am still paranoid about the radiation. It would be best for me to try and avoid a radioactive version for my peace of mind. Anyways, is there a way to know if the lenses are radioactive. The one i am looking at getting starts with 153 in the serial. And the glass looks yellow, but just on the front, so it might just be the coating. Anyways i was looking on pentax forums here:

    I took this directly from the page. It says "
    From the 1965 version, at least one of the glass elements is made from radioactive glass"

    They then tell you how you can differentiate the two:

    "1962: Super-Takumar 1:1.8/55 (first version) - fine knurls on aperture ring
    1965: Super-Takumar 1:1.8/55 (second version) - coarse knurls on aperture ring"

    So if i am understanding this correctly, only the second version out of these two has radioative glass. Anyways, how can i tell if the lens is the first version or second one. It mentions the knurls of the aperture ring but i am not sure how much of a difference in size they are. Anyways, does anyone know if this version of the lens is radioactive? I have a picture of the lens i was planning on getting here:

    Thanks in advance.
  2. barry13

    barry13 Super Moderator; Photon Wrangler Subscribing Member

    Mar 7, 2014
    Southern California
    I think those are the coarse knurls in that picture.

    Bananas and household smoke detectors are radioactive too.

  3. colbycheese

    colbycheese Mu-43 Veteran

    May 1, 2012
    Way up there.
    that's why i stay away from those as well :D 
  4. dwig

    dwig Mu-43 Top Veteran

    Jun 26, 2010
    Key West FL
    It's hard to tell in a photo attached to an ad. You might consider looking for the second all-black Auto-Takumar. This is actually the first "Super-Takumar" made in any focal length and ran from 1960-62 despite its naming. It's easier to distinguish this variant because of the naming. Just avoid the semi-auto diaphram version which is black and silver.
  5. Rum Maximus

    Rum Maximus Mu-43 Regular

    May 11, 2013
    LV, NV
    That's the coarse knurls on the focus ring. There's also the golden-brownish tinge to the lens that tends to be a hint that the glass is radioactive.

    I spent a few years hunting for a 2nd gen (7 element) Super Takumar 50mm f/1.4 simply because I wanted a radioactive one as a bookend to my 1st gen (8 element) Super Takumar 50mm f/1.4 lens. There's a significant difference in clarity of the glass between the two. It took a while before I tracked down one that was "just right" for me (ie - a nice golden tint to the glass).

    You can find a fairly comprehensive list of radioactive lenses here.

    For whatever reason, I find the radioactive lenses to be an interesting offshoot to collecting manual focus glass. Everyone seems to find their own particular genre of lenses once they figure out what they like - radioactive variants, "chrome nose" FD lenses, uncoated glass, certain date ranges, etc.
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