In this video I talk about the legendary, the glorious, the fantastic KONICA HEXANON AR 1.4/50. Three reasons why you will want one and one big reason why you should probably not get it.
I hope you like it.
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Hello @zerosapte, normally I don’t watch product videos on Youtube because they are nine times out of ten sooo boring. But not yours, you made me laugh several times and starting with a beer is at least original!
After having seen the intro, I skipped to the radioactivity part. Your topic interested me because there was one week ago a discussion on a Dutch analogue forum about the radioactivity of a Takumar 1.4/50 (for Asahi Pentax). Here’s a summary of some remarks in that thread.
Some people said that the radiation was below the background level so not dangerous. This kind of radiation is called alpha radiation: a piece of paper is enough to stop it. But don’t attach that lens on your head for 1 year, radioactivity levels might become a bit too high. Don’t let it drop either, there might be some radiation emitting from the broken glass (as you said as well). Don’t inhale that but you can touch the glass, alpha radiation doesn’t penetrate the skin.
Another person said that the isotope used for coating photographic lenses is thorium 228. This has a half-life of about 16 years. Your Hexanon is made from 1973 and 1978 (two series apparently), so there’s still about 1/8 of the original radioactivity left.
I’m not a chemical specialist at all, but I do have a Takumar as well, and I concluded after having read that thread that we don’t have to worry about our radioactive glass! So… Cheers! 
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Thank you for your feedback.
I happy I made you laugh. While I do try to be helpful and informative, I want to do it in a way that’s casual, light-hearted, relaxed and fun.
Regarding the radioactivity, my understanding is that it’s the glass itself that is radioactive, and not merely the coating.
However, while also not being a scientist, I did research the issue quite a bit and I think there at least two inaccuracies in your post.
Firstly, if I’m not mistaken, these radioactive lenses emit multiple types of radiation, including alpha, betta and gamma. While alpha radiation is indeed stopped by a thin piece of paper, the other two arw much more penetrative.
Furthermore, even according to Wikipedia, thorium has a much MUCH longer half life.
“All known thorium isotopes are unstable. The most stable isotope, 232Th, has a half-life of 14.05 billion years, or about the age of the universe; it decays very slowly via alpha decay, starting a decay chain named the thorium series that ends at stable 208Pb.”
However it is also my understanding that used with some precautions, these lenses are really nothing to worry about.
Mission accomplished !
I can’t comment on the inaccuracies in my post, I just compiled what I read in that Dutch thread.
The half-time you mentioned, from Wikipedia, is indeed a bit longer than 16 years! 
There’s one more thing to consider: have we ever heard about photographers who became “radioactive” after using Hexanon or Takumar lenses? Not me at least…
EDIT. Your Wikipedia half-time is about 232Th, for glass 228Th is used (indeed not as a coating but integrated in the glass). According to the English Wikipedia, the half-life of this one is 1.92 years. But once again, I’m not a scientist!
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Hmmm. Interesting. Have you got a source?
From the same English Wikipedia article:
Thirty radioisotopes have been characterised, which range in mass number from 209[22] to 238.[20] After 232Th, the most stable of them (with respective half-lives) are 230Th (75,380 years), 229Th (7,340 years), 228Th (1.92 years), 234Th (24.10 days), and 227Th (18.68 days).
Again, not a specialist here.
Yes, but how do you know which one was used for making optical glass?
I found this: “Radioactive lenses | Camerapedia | Fandom” Radioactive lenses | Camerapedia | Fandom
There is no indication anywhere of a special kind of thorium being used, so I would assume it has natural isotopic composition. If that’s the case, most of it would be Th-232 (“Isotopes of thorium - Wikipedia” Isotopes of thorium - Wikipedia).
Unless the thorium used comes from reprocessed spent nuclear fuel… 
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