I know this thread is old but thought this fits here. I just learnt about radioactive lenses and found this thread when searing for more info.
I also found this list of known radioactive lenses. The page is in Swedish (use google translate) but the list of lenses shouldn't cause bigger language problems. The bolded lines doesn't mean that lens is especially radioactive. It just means they have measured the radioactivity themselves. Cyberphoto is large camera shop, on- and offline.
https://www.cyberphoto.se/captains-log/radioaktiva-objektiv
It's mentioned at the end of the page that some brands also used thorium in the viewfinder glass, which they think can be a real health hazard since it's so close to the eye. They mention Pentax 6x7 and Pentacon Six.
They also offer to test your lenses for you - free of charge! They don't even require you pay the return shipping. I have a feeling this offer isn't international though! ;-)
Nothing to do with radioactivity, but you may want to look at their museum while you're there. Quite a collection.
https://www.cyberphoto.se/captains-log/kameramuseum
At the time, I bought a Geiger counter to measure radiation from a variety of lenses. I had too many from too many periods, so it was interesting to be able to test them all. I only had to get rid of the Takumars, the few others like the Killar or one Meyer are just mild and likely to be early lanthanum formulas - just don't put them under the pillow.
To me it's just amazing how some old rock can give high energy particles non stop for hundreds of years or more.
Can you buy a Geiger counter? Well, of course I understand that you can, but i thought they were very expensive.
There are all kinds of prices, from $50 to $3500, so they don't need to be expensive. The core of these things, simply put, are different sensors, much like a computer, the raw ability is mostly determined by the sensor type. One for alpha + beta + gamma may be around $150 (the tube / sensor, in the analogy).
I bought one that measures A+B+G and realize it was a bit overkill, way more precision that I need. But I also have some findings. Alpha is supposed to be blocked by air itself, it just bumps into it and releases the energy, just a few cms away it may be hard to detect. Beta is longer reaching, but is attenuated by clothing and will be blocked by thin aluminum. Gamma goes through everything, you'd need deep concrete or thick lead to block it.
The other aspect is is that radiation is a form of light. The further away you are, the dimmer, since the ways cover a full sphere. I may have this wrong, but assume it's inversely proportional to the surface of a sphere, which a quick google tells me it's 4 * PI * r^2. So if at 1cm the counter counts some radiation, at double the distance or 2 cm it's 1/4, at 3cm it's 1/9, at 4cm 1/12, at 8cm it's 1/64. So when you measure something, it may seem high, but be almost like background at a very small distance away from it.
I'm not concerned about my lenses, but I pick a lot of mushrooms and stuff from Chernobyl fell down on areas close to where I live.
I know nearly enough for me to have a good self-informed view of all the aspects. I think there all kinds of situations that may make something not very healthy seem innocuous, or something innocuous seem ominous. For example, one may try to live all healthy and not know some old plate set may be highly radioactive, or have tiles that are relatively active, which since they may cover a big surface, is enclosed may lead to radon being present.
It blew in our direction and it rained the days after. It would be great to be able to test mushrooms and berries from different areas.
This is the kind of thing I have no clue about, because you are eating this, and I am not sure but it will be within your system, something way different than say, a lens with some crystal with minor lanthanum.
I actually bought the A+B+G counter because I wanted to like the Takumars. The problem was it the count went to 50,000 CPM (and equally high m/Sv), then I put paper (which should block alpha) and it was the same reading, then I put 1 layer of alu sheet and it read the same. Then I put 16 layers of alu, and it read the same thing. It was all gamma rays.
It's likely bananas may be more dangerous, but I didn't want a gamma lighthouse when I had so many other and good 50mm lenses.
