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Radioactive lenses
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PostPosted: Thu Aug 07, 2008 2:29 pm    Post subject: Radioactive lenses Reply with quote

This is a follow up on a previous post about Industar 61L/Z and radioactivity

I leant my S-M-C Takumar 50/1.4 and Industar 61L/Z to a specialist in radioactive materials and I got some interesting answers.

The Takumar did indeed contain Thorium but the radiation was only measurable very close to the lens so it's really not that radioactive. Naturally occurring Thorium (232) has a half-life of 1.405E10 years. The Industar on the other hand did not emit any radiation and the explanation for that is that most likely made of naturally occuring Lanthanium. La-139 is stable and is 99.910% of naturally occurring Lanthanium. La-138 has a half-life of 1.02E11 years and is 0.090% of naturally occurring Lanthanium.

Naturally occurring Thorium and Lanthanium has a large half-life so it is most unlikely that decaying will have any impact on the lens. So the conclusion must be that it's pretty safe to buy lenses containing Thorium and Lanthanium.


PostPosted: Thu Aug 07, 2008 2:32 pm    Post subject: Re: Radioactive lenses Reply with quote

Damnit! And here I am saving up lenses for a bomb. Your telling me its futile?

PS. Hello FRA.


PostPosted: Thu Aug 07, 2008 3:28 pm    Post subject: Reply with quote

Actually, if you use them as projection lenses you get a Death Ray Machine.


PostPosted: Thu Aug 07, 2008 3:39 pm    Post subject: Reply with quote

Thanks, that was informative.


PostPosted: Thu Aug 07, 2008 4:17 pm    Post subject: Reply with quote

Takumars use thoriated glass only for the rear element. Radioactivity near front elment is very low, but near rear part it's higher than on famous aero-ektars.

at least these Asahi lenses use thorium:
  • Super / Super Multi-Coated Takumar 35mm / 1:2 (later version with 49mm filter thread)
  • Super / Super Multi-Coated / SMC Takumar 50mm / 1:1.4 (later Super version and all SMC)
  • Super / Super Multi-Coated Macro Takumar 50mm / 1:4
  • Super / Super Multi-Coated Takumar 55mm / 1:2

tomioka lenses:
  • Yashinon-DX 28mm / 1:2.8
  • Yashinon 55mm / 1:1.2
  • Yashinon-DS 50mm / 1:1.4
  • Yashinon-DS 50mm / 1:1.7
  • Yashinon DS-M 50mm / 1:1.4
  • Yashinon DS-M 50mm / 1:1.7
  • Yashinon DS-M 55mm / 1:1.2

earlier versions get yellowish cast, newer (DS-M) use other optical glue, which is stable doesn't turn yellow

There are 4 ways to remove the color cast:

1. sun (attention, curtains are highly flammable)
2. UV lamp + tinfoil (not good for eyes, best closed in case)
3. optical glue exchange (quite expensive)
4. so-called Ayling's method

I use 11W UV tube and 4 weeks is enough for removal of >95% color cast. Left: before, each next: 1 week under UV tube:



It should also eliminate spores of fungus.

There was a story about a photographer, who had some problems in a nuclear power plant, because the safety equipment analysed his camera as contaminated.

I've also read somewhere, that one day of photography (using radioactive lens) means same level of irradiation as one transatlantic flight.

here are some interesting links:

http://yashica.org/254-2-Lens-radioactivity-measurements.html
http://photo.net/large-format-photography-forum/005obo
http://www.orau.org/PTP/collection/consumer%20products/cameralens.htm


PostPosted: Thu Aug 07, 2008 4:52 pm    Post subject: Reply with quote

Mine seems to be ok (?)
Yashinon-DX 50mm 1:1.7 84nSv/h
Yashica ML 50mm 1:2 81nSv/h


PostPosted: Thu Aug 07, 2008 6:01 pm    Post subject: Reply with quote

I don't buy these lenses because I heard that if you carry any of them in your front pockets you will become sterile.


PostPosted: Thu Aug 07, 2008 6:24 pm    Post subject: Reply with quote

TheFlyingCamera wrote:
...don't sleep with the lens between your thighs or you'll have funny-looking children.
Very Happy


PostPosted: Thu Aug 07, 2008 7:26 pm    Post subject: Reply with quote

No it is NOT kidding. see >

http://homepage3.nifty.com/ohbehello/kizai_shitsu_page_lens_housyasen_list.htm
http://homepage3.nifty.com/ohbehello/the_fl_lens_waku2/fl_lens_housyasen_sokutei.htm

Natural background radiation is normally 0.020 - 0.045 micro Sv / H,
so some of them are pretty dangerous to your possible descendant(s).


PostPosted: Thu Aug 07, 2008 8:07 pm    Post subject: Reply with quote

According to US Code of Federal Regulations there are no restrictions in connection with lenses that contain less than 30 percent by weight of thorium.

Typical thoriated glass elements contains 2-4x time lower concentration of thorium. It should be safe for normal usage, but it's not reccomended to keep thoriated lens under your bed or to stock them (in larger quantities) in your bedroom, or just behind wall which is near upon your bed.


PostPosted: Thu Aug 07, 2008 8:12 pm    Post subject: Reply with quote

Thorium is an alpha emitter but has some gamma radiation which is the worst kind of external radiation. As also mentioned else where in this forum a fluorescent watch is also radioactive which only harmed the workers painting this material on. I guess it's the same reason that they don't make lenses with thorium element in them since the radioactive source is too vague to do any harm.

I think you will need an M42 to "scrutom" adapter and mount it a fair amount of time to achieve funny looking children.


PostPosted: Thu Aug 07, 2008 8:33 pm    Post subject: Reply with quote

Michael S. Briggs. wrote:
The statement that Thorium and its daughters decay via alpha and beta emissions is correct, but neglects the fact that many of the daughter isotopes are created in excited states. These excited isotopes quickly transition to their ground states by the emission of gamma-rays. The atomic electrons also readjust their states by the emission of X-rays. Blocking the X-rays and especially the gamma-rays require much more shielding than blocking alpha and beta particles.

http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html


PostPosted: Thu Aug 07, 2008 11:38 pm    Post subject: Reply with quote

In other words: should I sell my SMC Takumar 1.4/50?
Is it safe to take it with me for a holiday, so that it will stay most of the time either at my neck on the camera, or next to my waist inside the bag?


PostPosted: Fri Aug 08, 2008 2:52 am    Post subject: Reply with quote

Orio wrote:
In other words: should I sell my SMC Takumar 1.4/50?
Is it safe to take it with me for a holiday, so that it will stay most of the time either at my neck on the camera, or next to my waist inside the bag?


This seems to be an ever repeating theme, and once again, a concise explanation can be found at http://www.hps.org/publicinformation/ate/q1356.html.

I wouldn't worry, especially as the received dose will very quickly diminish with distance: at ten times the distance, the dose on a given area will be 1/100.

Veijo


PostPosted: Fri Aug 08, 2008 6:32 am    Post subject: Reply with quote

Orio wrote:
In other words: should I sell my SMC Takumar 1.4/50?
Is it safe to take it with me for a holiday, so that it will stay most of the time either at my neck on the camera, or next to my waist inside the bag?


You have to remember Orio, without radiation niether the Hulk or Spiderman would have been the superheros they are.

I would be more worried of mobile and wireless phones, especially the later. Wink


PostPosted: Fri Aug 08, 2008 7:08 am    Post subject: Reply with quote

Orio wrote:
In other words: should I sell my SMC Takumar 1.4/50?
Is it safe to take it with me for a holiday, so that it will stay most of the time either at my neck on the camera, or next to my waist inside the bag?


The reply I got from the specialist(s) was that the radiation was only measurable very close to the lens and that such small amount of radiation wouldn't harm. It's more likely that it's not used today to protect the assembly workers, or better materials has been discovered?

Both specialist should be a very reliable source since it's their job to warn about radioactive hazards (is that what it's called?)


PostPosted: Fri Aug 08, 2008 9:16 am    Post subject: Reply with quote

lauge wrote:
The reply I got from the specialist(s) was that the radiation was only measurable very close to the lens and that such small amount of radiation wouldn't harm. It's more likely that it's not used today to protect the assembly workers, or better materials has been discovered?

Both specialist should be a very reliable source since it's their job to warn about radioactive hazards (is that what it's called?)


Thanks for that clarification, now I don't have to worry that my one-year old daughter spend to much time near the cameras.


PostPosted: Fri Aug 08, 2008 7:51 pm    Post subject: Reply with quote

If you're going to get rid of your Pentax lenses send them my way Wink


PostPosted: Tue Aug 19, 2008 7:14 pm    Post subject: Reply with quote

zewrak wrote:

I would be more worried of mobile and wireless phones, especially the later. Wink

Very true!


PostPosted: Wed Oct 08, 2008 6:38 am    Post subject: Reply with quote

The Canon FL 58mm f1.2 is thoriated. Very nice but no reasonable way to convert to dslr.

Zuiko 55mm, not 50mm, f1.2 is thoriated. 55mm came first, and thorium couldn't make it sharp. 50mm is flat field sharp like a macro lens, 55mm might make a nice portrait lens like helios 40-2 but it's a lemon in the Zuiko line.

There you have it. Zuiko 55mm f1.2 thoriated does not always produce the right kind of funny babies, like X-M3n.


PostPosted: Wed Oct 08, 2008 7:29 am    Post subject: Reply with quote

Prometheus wrote:

Thanks for that clarification, now I don't have to worry that my one-year old daughter spend to much time near the cameras.


Or maybe you have to worry, but for your lenses Wink


PostPosted: Wed Oct 08, 2008 9:10 am    Post subject: Reply with quote

Zewrak wrote:

"PS. Hello FRA."

As a fellow Swede that made me laugh real good.

/Jan


PostPosted: Wed Apr 15, 2015 5:12 pm    Post subject: Reply with quote

Even the Yashica ML 50/2 is leaking some neglible Radiation? Well, i don't own the lens, but the 50/1.7 ML, 50/1.4 and many others...and guess what, the lenses are into a Box on my Bed, no kidding - because elsewhere i haven't found space for them...huh...


PostPosted: Mon Apr 20, 2015 10:29 am    Post subject: Reply with quote

doomed-forever wrote:
Even the Yashica ML 50/2 is leaking some neglible Radiation? Well, i don't own the lens, but the 50/1.7 ML, 50/1.4 and many others...and guess what, the lenses are into a Box on my Bed, no kidding - because elsewhere i haven't found space for them...huh...


That might not be the best idea - i keep my three radioactive lenses (three versions of the Minolta MC 2.5/28mm) a least 3 m away from where i work / sleep.

Steve


PostPosted: Mon Apr 20, 2015 5:40 pm    Post subject: Reply with quote

I know...i'd move them to my night cupboard.