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How radioactive are some of the "thorium" coated lenses? Looking at buying a Takumar lens. Stay away from it?
Radioactive lenses
- Thread starter Mozziephotography
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- John
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Not very. The radioactivity is inside the glass and is not going to escape to reach you. The radiation is beta radiation and not very energetic.
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I've tested a couple of allegedly radioactive lenses with a simple geiger counter that can read the Thorium in gas mantles. No reaction above background.
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Other lenses have been tested and found to be significantly radioactive. Don't use these lenses as loupes, or keep them on your bedside table, or (e.g.) leave them on loaded film cameras with cloth shutters for a prolonged period. The glass can also become discoloured.
View: https://www.youtube.com/watch?v=3ozOMssiP2E
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