Thorium glass - how bad is it?

[Coldkennels]

I bought a geiger counter after I found about about this a few years ago. My finding was that 80mm Biometar and a 50mm Flektagon were significantly radioactive....

Jesus, I own both of those lenses. Not used them since the Pentacon Six gave in back in 2012, but I still own them. Had no idea they were "hot". Luckily they're the less concerning "Zebra" versions!

According to the list @MNS posted - Radioactive lenses - the Zebra Flektagon comes in at 2.5-3.0 µSv/h. According to XKCD's radiation dose chart, one hour of exposure to said Flektagon is equal to thee arm x-rays, using a CRT monitor for three years, or eating 30 bananas (the Banana Equivalent Dose is a handy way to get some perspective on these things).

On a related note, Alfred Klomp tested the supposedly radioactive Industar 61 L/D years ago; there's a page about it on his site. There's no measurements in µSv, but it is slightly radioactive.

Maybe I'll have to buy a geiger counter myself...

 

[Freakscene]

I think that night vision devices were much worse. Regarding lenses and hazardous radiation, It is a never ending story full of speculations. Truth is that most lenses can be used safely. Who knows what emits potentially dangerous radiation in your household? I personally don‘t have a Geiger counter…

I do. Your smoke detector is the biggest source of radiation in your house, unless you picked up a piece of yellowcake from the roadside on a road trip through the Northern Territory 🙄

I have one of those Ross large format lenses in the lens swamp. It has its own special box.

 

[FotohuisR]

Well, I took my Geiger counter (because I am sometimes in Ukraine) and start measuring my lenses including that Industar L/D. It gives about 2x the back ground radiation which is almost nothing. Then I have tried my gas light. The Camping Gas light gives about 4x the back ground radiation and also here is Thorium involved. So I better can take care about that gas light which can break easily and then you have a bit radio active dust. So I don't think anybody has to worry about 2x radio active background glass.

 

[Freakscene]

Well, I took my Geiger counter (because I am sometimes in Ukraine) and start measuring my lenses including that Industar L/D. It gives about 2x the back ground radiation which is almost nothing. Then I have tried my gas light. The Camping Gas light gives about 4x the back ground radiation and also here is Thorium involved. So I better can take care about that gas light which can break easily and then you have a bit radio active dust. So I don't think anybody has to worry about 2x radio active background glass.

If you have travelled through or visited the Zone of Alienation (Зона відчуження Чорнобильської) in Ukraine, the Sick Country in the Northern Territory, or worked in a facility that uses ionising radiation, anything in a normal house is not even worth being concerned about.

 

[santino]

Allegedly the British army sold a lot of their Pentax cameras without lenses. Rumour has it that somewhere in Britain there are thousands of Takumars? (I don‘t know the lenses exactly) burried in a forest 😉

 

[Freakscene]

Allegedly the British army sold a lot of their Pentax cameras without lenses. Rumour has it that somewhere in Britain there are thousands of Takumars? (I don‘t know the lenses exactly) burried in a forest 😉

[gets his shovel]

 

[x-ray]

That was the other point that puzzled me. Although, I think it might be interesting using a changing bag to place a Thorium lens onto a small film strip and develop it to see if theirs is any effect.

It’s possible you’ll get an image. I’ve done this with the old Coleman lantern mantles years ago. The mantles today aren’t radioactive but for decades Coleman and other manufacturers of gas mantles coated them with thorium. It supposedly made them brighter and produce a whiter light.

When I was in high school in the 60’s I took a pack of Coleman mantles, a sheet it TX and placed a key under the mantles in a black paper bag. The next day I processed it and had a distinct shadow of the key.

Eleven years ago I was diagnosed with prostate cancer. I opted to haven radioactive palladium seed implants. When I had the procedure done I taped some coins to a film bag and placed a sheet of 400 iso film in it. I sat on it at lunch for a couple of days and then processed it. I was radioactive enough to actually expose an image.

I picked up 6 gas mantles from the 1800’s from an antique store. These are really radioactive and I’m going to recreate my key experiment when I get a chance.

 

[FotohuisR]

the Zone of Alienation (Зона відчуження Чорнобильської) in Ukraine

Well the Russian army digged in in this zone in the beginning of the war on 24th February 2022 when they had serious resistance of artillery from the Ukrainian army. They had to retreat from Hostomel and suburb villages of Kyiv, Bucha etc. and started killing (excecuting) citizens instead.

 

[Mackinaw]

I have a Canon FD 35/2.0, the first generation one with the concave front element and thorium element. Knowing that thorium is radioactive, I tried the “place the lens on photo paper overnight” experiment. When I developed the paper, it was inky black. For Canon users, the thorium FD 35/2.0 is a legendary lens, sharp and contrasty, even wide-open. Probably the FD lens I use the most.

Jim B.

 

[x-ray]

I picked up 6 of these antique thorium coated gas mantles in an antique shop. Yes these are radioactive and I plan to recreate imaging objects using these as a source of radiation.

 

[rfaspen]

Everyone should have a Geiger counter. Seriously.
I have at least two! 😬. I think it's fun and interesting to find out what's emitting particles around my house.

BTW, my 61LD doesn't register any emissions on any of my Geiger counters. I consider that un- lucky😕.

The 50/1.4 super tak on the other hand...

 

[Valkir1987]

Should avoid handling too much or just not worry about it?

I don't worry too much about it. But the people who worked in the grinding and polishing department in Zeiss Jena did worry back in the days. They wanted a thorium free version of the Jena Prakticar 1.4

Prakticar 1,4/50 | zeissikonveb.de
(chapter 4)

 

[Freakscene]

Well the Russian army digged in in this zone in the beginning of the war on 24th February 2022 when they had serious resistance of artillery from the Ukrainian army. They had to retreat from Hostomel and suburb villages of Kyiv, Bucha etc. and started killing (excecuting) citizens instead.

I went through long before 2022.

 

[p.giannakis]

I don't worry to much about it. But the people who worked in the grinding and polishing department in Zeiss Jena did worry back in the days. They wanted a thorium free version of the Jena Prakticar 1.4

Prakticar 1,4/50 | zeissikonveb.de
(chapter 4)

This website is a treasure trove.