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02-13-2022, 07:46 AM   #1
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Radioactive lenses

Dear,
I just discover that there are a vintage lenses with radioactivity due to Thorium used in construction process.
Now I bought a Pentacon auto 50mm 1.8 M42 (wonderful lens) with a clean and not yellow glass but I need to understand if this lens may be radioactive.
I am very concerned and thank you for your help.
Have a nice day.
Toni


Last edited by Toni60; 02-13-2022 at 07:52 AM.
02-13-2022, 07:55 AM   #2
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I have no idea if that lens has radioactive elements, but it should no be of concern. The radioactivity of camera lenses is very small. It would be a bad idea to sleep with it under your pillow for years on end, but otherwise you are likely to have greater radioactive exposure by standing outside all day or visiting a clinic to have an x-ray.
02-13-2022, 07:56 AM   #3
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@Toni60

I suggest you review this thread:

QuoteQuote:
Pentax radioactive lenses
I'm not a scientist but this video does make me a little nervous... Pentax is not the only one that made these type of lenses in the 1950's 60's and 70's. Other manufacturers include Kodak and Canon.
Pentax radioactive lenses - Page 4 - PentaxForums.com

and this

https://camerapedia.fandom.com/wiki/Radioactive_lenses
02-13-2022, 08:03 AM   #4
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Thanks for your reply, I just posted the message in the thread suggested. I think that is too old but I hope to have a reply.

Toni

02-13-2022, 08:11 AM   #5
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Thereís a lot of fear and not a lot of good data on radioactive lenses. The key is that you need to really review it to decide if it matters to you.

The facts:

Yes some lenses are radioactive.

Yes thereís debate about the risks. Most suggest the risk is vanishingly small if the lens is used correctly. Donít sleep wearing a pair as goggles. Donít grind up the elements and season food with them. Etc.

However - as someone with moderately damaged eyes I made the conscious decision to avoid these lenses. I figured that with my already compromised vision issues the tiny risk to my eyes was too much for the tiny utility gained by using these lenses vs others I have access to. To be fair it isnít really a rational decision but it is what it is.
02-13-2022, 08:13 AM - 1 Like   #6
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no one should fault either @UncleVanya or @Toni60 or anyone else for deciding not to use those types of lenses
02-13-2022, 08:15 AM   #7
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Thanks again I absolutely don't want to create problems to my daughter.

02-13-2022, 08:18 AM   #8
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QuoteOriginally posted by aslyfox Quote
no one should fault either @UncleVanya or @Toni60 or anyone else for deciding not to use those types of lenses
Lol. It keeps me from having a few more lenses than I already have as an added bonus!
02-13-2022, 09:17 AM   #9
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My understanding is that the thoriated lenses will emit alpha radiation.
Alpha radiation is not very active, in fact cannot even pass through a sheet of paper.
Only problems that exist are if the lens element is pulverized and the dust/particles are ingested.
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02-13-2022, 09:25 AM   #10
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Concerning the Pentacon, have a look at the link bellow.

Radioactive lenses
02-13-2022, 09:25 AM - 1 Like   #11
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I have a Geiger counter and measured my SMC 55MM f1.8 lens a few years ago. The rear element is the radioactive one. Right next to the lens the dosage is about half that of a modern x-ray. It falls away rapidly as you move away from the element. :Once you are a meter or so away any radioactivity is lost in the background radiation. (Around 50 CPM where I live).


If you install it on a camera there are no problems. My lens is slightly yellow, but not really a problem.
02-13-2022, 10:17 AM   #12
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I was given a couple of Takumar radioactive lenses - both are yellow - by a friend who used them from the 1960s/1970s on. He is in his early 80's now and is quite healthy, no eye problems at all. Not a scientific analysis, but there it is.

Last edited by MikeStnly; 02-13-2022 at 10:17 AM. Reason: Fixed typo.
02-13-2022, 10:30 AM - 3 Likes   #13
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Radioactive lenses make me tingly all over
02-13-2022, 12:35 PM - 1 Like   #14
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QuoteOriginally posted by Toni60 Quote
Now I bought a Pentacon auto 50mm 1.8 M42 (wonderful lens) with a clean and not yellow glass but I need to understand if this lens may be radioactive.
I am very concerned and thank you for your help.
Toni
Thoriated glass will yellow; I've never known one that didn't. So if yours is not yellow, it's safe to say it's not radioactive.

I've used a geiger counter on several Super Takumar 50mm primes and they all emit alpha, beta, and gamma radiation. If you don't have access to a geiger counter, a cheap test is using a portable AM radio and tuning to a space between stations. As you put it close to another manual focus lens, or one that you're certain isn't using a thoriated element, listen to the level of static. How does that compare with your Pentacon? If the Pentacon creates much more static noise, it probably has thoriated glass.

As others have posted, relative to air travel, X-rays, or spending a lot of time outdoors, the amount is relatively small and is a very low risk if the lens is used as intended.
02-13-2022, 02:19 PM - 1 Like   #15
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Just do not use the camera lens while wearing an old glow in the dark watch, you do not want to mix the thorium and the radium together.
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