Thoriated lenses for MF Mamiya cameras (RB/RZ67, C330)?

Drone · Dec 10, 2014

I have been looking for a good and reasonable MF kit set already for some time, and I will probably end up with Mamiya RB/RZ67 or Mamiya C330 TLR (or both). As RB 67 and C-series TLRs were designed in the 60-70's, I am wondering whether thoriated (radioactive thorium) was used in their typical lens lineup (Sekor, Sekor C, Sekor K/L, Sekor Z and Sekor TLR lenses)?

I have been browsing through many sources in the internet and it seems that some 35mm (M42?) Sekor lenses had models with thoriated (hot) glass. I haven't found though any information on RB/RZ67 or C330. One symptom of this is yellowing of the glass over time, but it seems that many of these lenses may use yellow/amber colored non-radioactive coatings anyway. Fortunately, by using geiger-counter with alpha-particle detection spotting a hot-glass should be easy (as long as just one has the glass and counter already ).

flavio81 · Dec 10, 2014

Yellowing of glass over time is not the same as amber/yellow coatings. Coated lenses are supposed to be color-neutral when looking through the lens.

My advice? Don't worry. Even if you have one of the highest radioactive lenses such as the early 50/1.4 Takumar, it's not of too much concern, unless you want to sleep with the lens next to you everynight.

There is tons of info on this subject on the 'net, and i have never ever found mentioning of the Medium Format Sekors being radioactive. And if they were, i would be happy, since this means that Mamiya used the most expensive glass available then.

Drone · Dec 10, 2014

There is tons of info on this subject on the 'net, and i have never ever found mentioning of the Medium Format Sekors being radioactive.

Exactly! I haven't found either, and this is why I try to find it out.

I am not so much concerned about the emitted radiation dose (as long as one does not keep stuffs 0.5m away, several hours per day). I find it more dangerous that the lens can get dropped and shattered into small pieces (in lungs or under skin this could become an issue).

Gerald C Koch · Dec 10, 2014

If you are worried about the radiation from thorium glass lenses then never visit the black sand beaches of Hawaii. The sand is quite radioactive being formed from lava.

I have several of these lenses both the Takumar and the Russian RF ones. Any concern about them is very far down on my list of worrisome things. BTW. I have an MS in nuclear chemistry. so relax and enjoy using them.

benjiboy · Dec 10, 2014

Don't worry, a little knowledge is dangerous, I've owned a Canon 35mm f2 Thorium lens for almost forty years and in a few months I'll be 76 and I'm fit and healthy. read this http://photo.stackexchange.com/ques...f-dose-can-you-expect-from-a-radioactive-lens

Theo Sulphate · Dec 10, 2014

My philosophy is: "a little radiation never hurt anyone"

For the early Takumar 50/1.4, I've heard that the yellowing can be "cured" (?) by exposing it to UV light (or, to a lesser extent, the Sun). Personally, I'd never bother or worry about it.

Xmas · Dec 10, 2014

Thorium was banned because of the airborne dust during polishing pervading the whole facilities. Ditto lead.

Don't worry.

Dan Fromm · Dec 10, 2014

Drone said:
I haven't found either, and this is why I try to find it out.

Ah! The old "If I can't find any they must exist and be very well-hidden. I'll have to look harder." delusion.

Athiril · Dec 10, 2014

You'll much likely get a bigger dose of radiation eating a banana, taking a plane flight, or living in a brick building.

Drone · Dec 10, 2014

Thank you for the vacation tips and rigorously rationalized radiation safety info.

Still no one answered the question if thorium was used in MF Sekor glass or not ...

Alan Gales · Dec 10, 2014

Here you go!

https://www.youtube.com/watch?v=6Aq5cqjUFOo

Theo Sulphate · Dec 10, 2014

Drone said:
Thank you for the vacation tips and rigorously rationalized radiation safety info.

Still no one answered the question if thorium was used in MF Sekor glass or not ...

If anyone wants to get rid of their radioactive lenses, send them to me; I can always use more lenses. In return, I will send some nice red-glaze Fiestaware from the 1930's.

AgX · Dec 10, 2014

Drone said:
I find it more dangerous that the lens can get dropped and shattered into small pieces (in lungs or under skin this could become an issue).

This is already a issue with a industrial dump of glass dust.

Roger Cole · Dec 11, 2014

Theo Sulphate said:
If anyone wants to get rid of their radioactive lenses, send them to me; I can always use more lenses. In return, I will send some nice red-glaze Fiestaware from the 1930's.

I'll take 'em too. Especially the Takumars since I have Pentax cameras both K and M42.

Xmas · Dec 11, 2014

Visit Chenobyl instead.

Poisson Du Jour · Dec 11, 2014

A couple of early Pentax 6x7 Takumars used thorium in the elements line up (chiefly the front element). All sorts of spooks and sooks stories circulating on the web are as good as ignored. Travel next to the window in a plane for 11 hours and you'll get a hell of a lot of radiation. No big deal to pick up these or any other thorium element lens, either for practical photographic use of bragging rights. To be sure, a lot of achievements in optical technology have been made in the many years since thorium was added to glass for whatever effect, other than the commonly seen yellowish tinge that causes people to routinely head off on a freaky, bollocky-riddled bender. Radiation, contamination, infertility, blindness, mental derangement... the bullshit on the web goes on and on. Buy what you fancy and have some fun.

benjiboy · Dec 11, 2014

My eldest son is a nuclear physicist who works at at a leading U.K nuclear facility and he tells me there is more radiation than I'm getting from my Canon FD Thorium lens coming from the granite work surfaces in our kitchen and it doest represent 1/10th of the annual radiation dosage that workers in his industry are allowed safely to absorb, and that as long as I don't sleep with it under my pillow it's perfectly safe and Thorium emits alpha particles that only have a range of an inch or two.

lxdude · Dec 11, 2014

Poisson Du Jour said:
Radiation, contamination, infertility, blindness, mental derangement...

And then there are the negative things...

lxdude · Dec 11, 2014

Drone said:
Still no one answered the question if thorium was used in MF Sekor glass or not ...

I searched, and it turns out that lots of lenses used radioactive glass. It appears that only one lens from Mamiya is radioactive, and that is a 50mm for the 135 format cameras. You're welcome.

benjiboy · Dec 11, 2014

lxdude said:
And then there are the negative things...

Radiation, contamination, infertility, blindness, mental derangement..[/QUOTE]

I'm not worried at my age I already suffer from two of the three afore mentioned.

Dan Fromm · Dec 11, 2014

benjiboy said:
My eldest son is a nuclear physicist who works at at a leading U.K nuclear facility and he tells me there is more radiation than I'm getting from my Canon FD Thorium lens coming from the granite work surfaces in our kitchen and it doest represent 1/10th of the annual radiation dosage that workers in his industry are allowed safely to absorb, and that as long as I don't sleep with it under my pillow it's perfectly safe and Thorium emits alpha particles that only have a range of an inch or two.

Here's the story: http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html

Ben, Thorium's decay products are much worse than Thorium itself. Thoriated lenses are harmless in normal use but I wouldn't carry one as a good luck charm in a pants pocket even though, e.g., a 55/8 Repro Claron is small enough to serve.

E. von Hoegh · Dec 11, 2014

Dan Fromm said:
Ah! The old "If I can't find any they must exist and be very well-hidden. I'll have to look harder." delusion.

(peels banana, takes a bite)

flavio81 · Dec 11, 2014

There is an article (by Marco Cavina) that analyses some propietary (i.e. specific to Nikon, Leitz, Zeiss) optical glass compounds, and there was one of them - i think it was for Leitz ELCAN - that had like 80% thorium oxide!

Rick A · Dec 11, 2014

benjiboy said:
Don't worry, a little knowledge is dangerous, I've owned a Canon 35mm f2 Thorium lens for almost forty years and in a few months I'll be 76 and I'm fit and healthy. read this http://photo.stackexchange.com/ques...f-dose-can-you-expect-from-a-radioactive-lens

Yeah, but when you bought uit you looked like Cary Grant, now you resemble Wallace(or is it Grommet?)Is the lens to blame?

benjiboy · Dec 11, 2014

Rick A said:
Yeah, but when you bought uit you looked like Cary Grant, now you resemble Wallace(or is it Grommet?)Is the lens to blame?

Ah, that could explain it Rick, but I was never as handsome as Cary Grant even forty years ago, nor I can assure you have I ever looked like Wallace, and I can't even attribute the way I look to being irradiated, only the passage of time

Thoriated lenses for MF Mamiya cameras (RB/RZ67, C330)?

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