[boriscleto]

I just received the Super Tak 35/2 I purchased from Shopgoodwill. It is a V1 with 67mm filter ring and no Thorium elements. My question is how do you tell the early V1 from the late V1?

[glasbak]

My 67mm filter size super tak 35/2 is radioactive, how do you know yours is not ?

[boriscleto]

My 67mm filter size super tak 35/2 is radioactive, how do you know yours is not ?

All sources I have seen say the 49mm thread 35/2 is Thoriated, not the 67mm. Mine is not yellow, so unless someone de-yellowed it it is not Thoriated.

The late version of the 67mm 35/2 was introduced in 1966 so it may have been Thoriated. The Thoriated 50/1.4 was introduced in 1965. I know some claim there are Thoriated 55/1.8s and 55/2s too, but the sources I have seen don't back that up either.

[glasbak]

All sources I have seen say the 49mm thread 35/2 is Thoriated, not the 67mm.

I know some claim there are Thoriated 55/1.8s and 55/2s too, but the sources I have seen don't back that up either.

Time to add a new source:

Youtu.be

Youtu.be

If your 35/2 is not radioactive, you have your early/late version differentiator found.

[lytrytyr]

Time to add a new source:

Interesting.

But this does get me wondering.

If the radioactivity is such a big deal,
how come no-one ever complained
about their films getting fogged
back in the day?

[Lloydy]

Radioactive materials in camera lens

This seems like information from an organization that should know something about it.

http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1717/nureg-1717.pdf the full document.

I have seen video of someone testing a lens then testing the granite worktop in a kitchen, and the worktop beat the lens hands down!
I'm keeping my old Tak's.

[lytrytyr]

Radioactive materials in camera lens

This seems like information from an organization that should know something about it.

Good perspective.

Just don't let it fall into the hands of the MILC lobby,
or we'll start hearing about radioactive optical viewfinders!

"Of significantly more concern is the possibility that the eyepiece itself employs a thoriated lens. This has been the case in some military devices and some unauthorized commercial devices. This is a much greater problem because of the proximity of the eyepiece to the eye and the fact that alpha and beta emissions now contribute to the dose. If the eyepiece is radioactive, the germinal cells of the cornea become the tissue of concern and the potential annual dose becomes quite high."

[glasbak]

If the radioactivity is such a big deal,
how come no-one ever complained
about their films getting fogged
back in the day?

It's not a big deal, but using a radioactive eyepiece could be unadvisable because of the short distance to the eye.

I have read that if you put a radioactive takumar 50/1.4 for a few weeks on a piece of photographic paper, you could see some effect, but in a camera the distance film to lens is already quite large (45mm), and the radiation very low.
So don't worry.

[lytrytyr]

It's not a big deal,

Sorry, my post did not use "international" English.

In colloquial English, "If . . . is such a big deal, . . . "
implies that I don't think it is.

but using a radioactive eyepiece could be unadvisable because of the short distance to the eye.

That seemed to be the issue raised in the report David quoted.

I have read that if you put a radioactive takumar 50/1.4 for a few weeks on a piece of photographic paper, you could see some effect, but in a camera the distance film to lens is already quite large (45mm), and the radiation very low.

There were times when people used to carry film next to lenses in a bag.
With the film only a couple of millimeters from the glass,
one might have expected any significant radiation to be noticeable.

[glasbak]

Sorry, my post did not use "international" English.
There were times when people used to carry film next to lenses in a bag.
With the film only a couple of millimeters from the glass,
one might have expected any significant radiation to be noticeable.

Most radiation from thorium is alpha particles, easily blocked by a few cm air, a lens cap, or a film cannister.

[Lloydy]

Some of the other stuff on the Gov't Commission document is interesting, we don't really think that the auto shifter in our cars is radioactive.

[boriscleto]

After taking a look at Blue's serial # database I am sure it is a late V1. So if this is a radioactive lens someone de-yellowed it. Or it just saw constant use.