[Digitalis]

Yes, this is a radioactive lens element taken from a Takumar 50mm f/1.4.



In all the years radioactive Takumar lenses* have existed (and the viciously radioactive Koadak Aero Ektar large format lenses) I have never heard of anyone being directly injured or become sick due to use of these lenses.



*there are also some Canon, Konica, Voigtländer, Nikon, Zeiss and Leica lenses from circa 1940~1970s that used glass tainted with radioactive elements too. Typically thorium oxides were involved: however oxides of strontium 90 and caesium137 have been reported in some of the more intensely radioactive lenses - both of which are substantially worse.

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Last edited by Digitalis; 02-14-2022 at 10:34 PM.

[Paul the Sunman]

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.

Don't jest. Someone may take you seriously.

[Bob 256]

In recently viewing a YouTube posting (take this for what it's worth), Thorium is actually a bi-product of many mining processes, so much so, it can be a problem to get rid of, so some manufactures (Asian) blend it into certain products just to get rid of the stuff (an ink pen was one example). This makes the product mildly radioactive but more than enough to register on a radiation detector. Now this doesn't worry me too much but my OCD will now have me checking everything in sight since most of it is of Asian origin these days. That does worry me.

Youtu.be

Youtu.be

[stevebrot]

My understanding is that the thoriated lenses will emit alpha radiation.

They also emit gamma, hence the creation of so-called color centers in the glass.


Steve

[MarkJerling]

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

Hi Toni

I note you live in Italy. Be aware that the soil under your feet, in Italy, contains anywhere from 15 to more than 26mg of Thorium per kg of soil. (For most of central and Northern Italy) You're also standing on anywhere from 2.5 to 9.7mg of Uranium per kg of soil. Many other natural products such as granite kitchen benchtops and other natural stones are radioactive to a small degree. See Digital Atlas

Unless you feed the lens to your daughter for breakfast, you or her are exceedingly unlikely to experience any ill effect.

Enjoy your Pentacon lens.

Kind regards,
Mark

[pentaxus]

The possible danger of using radioactive lenses was always known. Using thorinated glass for eyepiece or viewfinder lenses was always illegal. An SLR has all sorts of stuff in the way before light goes through the eyepiece.

[photogem]

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

No Thorium in this lens.
None of the Pentacon lenses had Thorium as far as I remember.
But the facts brought be Mark are valuable, not to worry with lenses such as the Takumars containing Thorium.
Only if they fall on the floor and burst and you inhale glassdust or lick it up.
So to store them save and all is well.

I have quite a few of them, also some vintage Ricoh versions.

[Digitalis]

The radioactivity of the Takumar 50mm lenses is utterly overblown and sensationalized*, I wear watches from Luminox and to quote from their website "The watch hands and markers contain radioactive tritium inserts which provide long-term luminescence. The tritium undergoes beta decay, releasing electrons which cause the phosphor layer to fluoresce". FYI...I have never had problems with airport security when wearing these watches.



* There have been several youtube personalities that used un-calibrated equipment to measure the radioactivity of theses lenses and their readings were so far off the mark they amount to be utterly useless scaremongering.

[35mmfilmfan]

A friend was going to get Granite work surfaces in her new kitchen - until I mentioned that Granite is naturally slightly radioactive, so she got MDF instead. She was actually working in a 100 or so year old building constructed mainly from Granite at the time.

[Digitalis]

A friend was going to get Granite work surfaces in her new kitchen - until I mentioned that Granite is naturally slightly radioactive, so she got MDF instead.

Have you told her about Bananas yet?

[35mmfilmfan]

Have you told her about Bananas yet?

No, but she got really annoyed once when we were shopping and she told me to leave her in peace and do something useful. When she found me, I was using a pocket compass (no mobile phones in those far-off days) to align all of the bananas in the Produce section so they pointed North - South. I suffered no ill-effects - from the bananas, anyway.

[reh321]

No, but she got really annoyed once when we were shopping and she told me to leave her in peace and do something useful. When she found me, I was using a pocket compass (no mobile phones in those far-off days) to align all of the bananas in the Produce section so they pointed North - South. I suffered no ill-effects - from the bananas, anyway.

When I was a grad student, I had a summer internship at a place called “Los Alamos”.
During a tour I accidentally touched a fuel rod made of real uranium.
We also stood in front of our house when they went around “fogging” with DDT to kill mosquitoes.
That was about 50 years ago.
I’ve fathered two perfectly normal daughters since then.

[Digitalis]

During a tour I accidentally touched a fuel rod made of real uranium.

Briefly touching uranium metal isn't particularly bad - our hands are mostly bone,muscle and skin and have the ability to withstand a bit of cellular damage without incident. Assuming if the sample of uranium was the appropriate shape and you decided to wear it as a hat*, it would in all probability deliver a fatal dose of radiation in under an hour to your brain.


* Isn't Los Alamos where they had that prompt criticality incident with the "demon core"?

[Alex645]

Six years ago I ran a test with two lenses and got these results:

Kodak Instamatic Ektar lens: 50 mR/hr with no barrier.
Super Takumar lens: 500+ mR/hr with no barrier.
Super Takumar lens: 250 mR/hr with a plastic or aluminum rear cap barrier.
Super Takumar lens: 100 mR/hr with a lead barrier.

Alpha particles would be blocked with any lens cap.
Beta particles would be blocked by the lead barrier.
Gamma radiation went through the 1/2 inch lead shield.

@Digitalis' chart helps for us to understand that radiation is all around us and that just because some objects are more radioactive than others, doesn't necessarily mean it's significantly harmful.

[MarkJerling]

During a tour I accidentally touched a fuel rod made of real uranium.

There's so much in that one sentence.

"Tour" (What could go wrong?)
"Accidentally touched" (What could go wrong?)
"Uranium" (What could go wrong?)

I love it.