Are these lenses radioactive? ☢️😲

I've had a film era Pentax Asahi lens for years that I suspected was radioactive. Though, many sources said that the version I had wasn't. That motivated me to buy a low cost Geiger counter to see for myself if that lens or any of my others measured above ambient. Don't take my results and what I say here as perfect. I'm learning this as I go. ;) Doing your own research and testing is part of the fun! That yellowing of the Asahi Super Takumar 50mm is real and likely due to the radioactive element in the glass. My specific copy of the lens is serial number 1381406. It does have the orange infrared focus mark right of the numeral 4 on the depth of field scale, so it should be one of the 8-element versions. Maybe the really radioactive version measure higher but 0.92 usv/h is decently high in itself.

Check out the cheap Geiger counter I used in this video:
https://amzn.to/3GqVT9S
Pentax Asahi Super Takumar 50mm f1.4 Lens:
KEH: https://shrsl.com/29oxb
ebay: http://ebay.us/6bsUgi

Information Sources:
https://www.pentaxforums.com/lensrevi...
https://camerapedia.fandom.com/wiki/R...
https://en.wikipedia.org/wiki/Thoriat...
https://www.sciencefocus.com/science/...
https://cs.stanford.edu/people/nick/g...
https://xkcd.com/radiation/

#RadioactiveLenses #RadioactiveCameraLenses #CameraLenses

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