50mm Lens Comparison – Radioactivity

14 thoughts on “50mm Lens Comparison – Radioactivity”

  1. Well done! Kudos to your thorough approach ๐Ÿ™‚

    I’m curious though.. in regards to the Takumar,
    if a rear lens cap absorbs 40%. of the radiation.
    What of a camera body, could it absorb twice
    as much or in fact all of it?

    Because I imagine this is a more common scenario
    for such a lens, unless of course one carries a zillion
    lenses along on photo excursions.


    1. Hi Eva.
      The absorption of radioactivity depends on the density of the material (that’s why lead is so effective at this).
      Of course, a camera body with several layers of plastic, glass or even metal in-between lens and photographer is bound to reduce the level of radiation more than a simple lens cap would.


    1. Hey, funny that you should ask ๐Ÿ™‚

      I just measured it this week and it’s definitely radioactive. Radiation is mainly emitted from the rear element and it’s not as intense as the Takumar, but still quite impressive.
      Really didn’t see that coming.


    1. I’m fairly certain that none of the 35mm format Pentacon branded lenses are radioactive. You could always measure it with a Geiger Counter. Take it to the physics department of your (or your kids) school/University and let them quickly measure it. Takes 1 Minute to do so and you’ll have absolute certainty.

      Be advised, however, that everything has a certain amount of radioactivity to it, so a measurement of 0 (mSv, R, Bq, etc.) would be a device error.


  2. @danielpetessondemo
    Hey 0.13 ฮผSv/h is 0.00013 mSv/h, which is about the same as I measured for background radiation in our physics department. That means the lens has not been manufactured using any radioactive glass.

    Truly radioactive lenses will be 100 – 1’000 times more radioactive at close distances (3cm from the glass surface)


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