Radioactive lenses

**Toni60** · 02-13-2022, 07:46 AM

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.

pschlute · 02-13-2022, 07:55 AM

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.

**aslyfox** · 02-13-2022, 07:56 AM

@Toni60

I suggest you review this thread:

Quote:

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

**Toni60** · 02-13-2022, 08:03 AM

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

**UncleVanya** · 02-13-2022, 08:11 AM

There’s 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 there’s debate about the risks. Most suggest the risk is vanishingly small if the lens is used correctly. Don’t sleep wearing a pair as goggles. Don’t 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 isn’t really a rational decision but it is what it is.

**aslyfox** · 02-13-2022, 08:13 AM - **1 Like**

no one should fault either @UncleVanya or @Toni60 or anyone else for deciding not to use those types of lenses

**Toni60** · 02-13-2022, 08:15 AM

Thanks again I absolutely don't want to create problems to my daughter.

**UncleVanya** · 02-13-2022, 08:18 AM

Originally posted by aslyfox

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!

**FozzFoster** · 02-13-2022, 09:17 AM

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.

**Papa_Joe** · 02-13-2022, 09:25 AM

Concerning the Pentacon, have a look at the link bellow.

Radioactive lenses

**gaweidert** · 02-13-2022, 09:25 AM - **1 Like**

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.

MikeStnly · 02-13-2022, 10:17 AM

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.

Roadboat24 · 02-13-2022, 10:30 AM - **3 Likes**

Radioactive lenses make me tingly all over

**Alex645** · 02-13-2022, 12:35 PM - **1 Like**

Originally posted by Toni60

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.

**VSTAR** · 02-13-2022, 02:19 PM - **1 Like**

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.

02-13-2022, 07:46 AM	#1
Toni60 Site Supporter Join Date: May 2013 Posts: 97	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, 09:17 AM	#9
FozzFoster Custom User Title Join Date: Jan 2016 Location: Alberta Photos: Albums Posts: 6,337	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. Attached Images

02-13-2022, 10:17 AM	#12
MikeStnly Senior Member Join Date: Jun 2012 Location: Algonquin Highlands Posts: 249	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.

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02-13-2022, 07:55 AM	#2
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 6,337	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
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,316	@Toni60 I suggest you review this thread: Quote: 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
Toni60 Site Supporter Join Date: May 2013 Posts: 97 Original Poster	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
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 24,481	There’s 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 there’s debate about the risks. Most suggest the risk is vanishingly small if the lens is used correctly. Don’t sleep wearing a pair as goggles. Don’t 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 isn’t really a rational decision but it is what it is.

02-13-2022, 08:13 AM - 1 Like	#6
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,316	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
Toni60 Site Supporter Join Date: May 2013 Posts: 97 Original Poster	Thanks again I absolutely don't want to create problems to my daughter.

02-13-2022, 08:18 AM	#8
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 24,481	Originally posted by aslyfox 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, 09:25 AM	#10
Papa_Joe Site Supporter Join Date: Sep 2018 Location: SW Bavaria Posts: 427	Concerning the Pentacon, have a look at the link bellow. Radioactive lenses

02-13-2022, 09:25 AM - 1 Like	#11
gaweidert Loyal Site Supporter Join Date: Mar 2012 Location: Rochester, NY Photos: Gallery Posts: 5,146	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, 10:30 AM - 3 Likes	#13
Roadboat24 Pentaxian Join Date: Jul 2017 Posts: 384	Radioactive lenses make me tingly all over

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02-13-2022, 12:35 PM - 1 Like	#14
Alex645 Site Supporter Join Date: May 2015 Location: Kaneohe, HI Photos: Albums Posts: 3,358	Originally posted by Toni60 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
VSTAR Loyal Site Supporter Join Date: Mar 2010 Location: Toronto Posts: 390	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.