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07-13-2015, 06:27 PM   #16
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Don't fly....Don't talk on cell phones ..... don't get X-rays at the hospital .....don't go through airport security ......and last but not least.....stay out of the sun ! All of these are radiation sources too.
I know that a thorium glass lens is not any worse than the fact its a minute miniscule amount compared to the above..........Relax ........take some vit C and E with Selenium if your worried.....and simply enjoy your lens !
I would worry more about Japans Fukishima Nuclear reactor that is now detectable world wide , than anything else. Radiation is All around us every day.
And.....for what its worth....I worked at W.I.P.P ( Waste Isolation Pilot Plant) in Carlsbad New Mexico for several I guess You could say I know a bit about radiation

Last edited by Dlanor Sekao; 07-13-2015 at 06:41 PM.
07-13-2015, 07:02 PM   #17
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That's great in theory. My cat had kittens. They all have 6 toes and two tails. Kinda seems to bust the " safe" theories, eh.
07-13-2015, 07:05 PM   #18
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QuoteOriginally posted by MadMathMind Quote
You'd be exposed to more radiation on a single air flight than a lifetime for a lens or even a radium watch from yesteryear.

Heck, if you live in Denver, you get even more radiation than that on a daily basis from the granite.
I was going to raise this point, but now I'll just say +1.

Coincidentially, I own a variety of early wrist watches with luminous hands. These are all mildy radioactive. But, the simple reality is that you'll probably get more radiation exposure from your home's smoke detectors. And, as a bonus, my left wrist is showing no signs of a lifetime of radioactive wrist watch wearing!
07-13-2015, 07:22 PM   #19
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QuoteOriginally posted by condor27596 Quote
That's great in theory. My cat had kittens. They all have 6 toes and two tails. Kinda seems to bust the " safe" theories, eh.
Cats with six toes are the result of an inherited genetic mutation

I wouldn't think that is related

A s I said back on page 1 the issue is more one of worker exposure and to a much lesser extent disposal, although from all the discussion about old radioactive lenses it seems most of them are still in circulation.

As others have noted, old radium painted watch dials are radioactive , and from personal experience I can remember seeing my fathers wrist watch set off the hand detector at a nuclear facility during a tour.

07-13-2015, 07:33 PM - 2 Likes   #20
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After reading several articles....Im going to make an estimated semi educated quick calculation that 10 mrem (.10mSv) per year would be the absolute maximum exposure in the worst case scenario. I based this on the industry standard maximum of Thorium oxide at 30% of a lens. In reality I have no exact data of thorium oxide content for our Pentax Takumar lenses ? Im making an assumption its at about 12% but this is nothing more than an educated guess. Even my figure would be very high as I calculated a 12 hr a day exposure at less than 12". This would be the maximum possible exposure , not what was actually absorbed internally. Like dcshooter said....many things block it. Clothing , skin , even the camera bag or metal body of the camera its self.
In reality I would estimate my possible personal exposure at less that .5 mrem per year for weekly sporadic use........I could get get more from the granite counter tops in my kitchen than from a Takumar lens !

This was the first time I stopped to look at any data. Im putting it to rest for myself as I always wondered if there was even a miniscule chance of being an issue.....Now I know. Its a Non Issue......and Im very cautious of such things.

On top of it all there are about 30 known isotopes of thorium and its not completely clear to me which one we are even talking about for sure ? I used the worst case scenario for my over the top maximum calculation........hope this helps.

Last edited by Dlanor Sekao; 07-13-2015 at 08:12 PM.
07-13-2015, 08:04 PM - 1 Like   #21
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07-13-2015, 08:34 PM   #22
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QuoteOriginally posted by luftfluss Quote
You my friend....Are Over the Top ! I love it !
07-13-2015, 08:34 PM   #23
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QuoteOriginally posted by dcshooter Quote
First, radiation exposure follows the inverse square of distance, so at even a foot away, you are getting a biologically insignificant exposure.
Another reason to have a K-01

07-13-2015, 08:34 PM - 1 Like   #24
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It's all harmless, my left head was telling the right one this morning!
07-13-2015, 08:45 PM   #25
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QuoteOriginally posted by clackers Quote
It's all harmless, my left head was telling the right one this morning!
Even though I say its harmless.....I wont carry this lens around in my pocket ! But then again I don't carry a cell Phone ........... And haven't flown for a long time either !
I get my daily dose of radiation here in Carlsbad NM from the Nome Project........not many even know this......... Its still quite detectable and largely covered up. It wasn't suppose to be powerful enough to breech the surface.....IT DID.......and still detected today. As far as Im concerned Carlsbad NM isn't fit for habitation due to excessive radiation levels. This was the FIRST Atomic bomb test in the USA !

Last edited by Dlanor Sekao; 07-13-2015 at 09:03 PM.
07-13-2015, 09:58 PM   #26
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Don't duct tape the lens to you forehead. Either it will kill your brain cancer or cause it. Not knowing is the problem.
07-13-2015, 10:53 PM   #27
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Thorium is all the rage these days.

Have a look at this:

Molten Salt Reactors (incl Liquid Fluoride Thorium Reactor) | No CO2, No High Pressure, No Loss of Coolant Accidents, No Long-Term Radioactive Waste

and then the rebuttal by the no-nukers:

Thorium: Not Green, Not Viable and Not Likely, Oliver Tickell, June 2012

07-14-2015, 06:21 AM   #28
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I'm very intrigued by the idea that the alpha radiation converts to gamma radiation. It seems this is how The Hulk got his start. I'm currently taping my lenses to my biceps. I will post results as the happen.
07-14-2015, 07:25 AM   #29
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You get more radiation standing in the sun. You can reverse the yellowing in many takumars by letting them bask in the direct sunshine for a while.
07-14-2015, 11:21 AM   #30
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Americium 241 is at a level significantly higher than a Takumar lens.......where is it found ? The smoke detector in your Home ! Now lets all worry
Also cigarettes also contains about 100 mrem per hour of Radon.......That's It !!!! .......................We are All "DOOMED" !

Last edited by Dlanor Sekao; 07-14-2015 at 11:37 AM.

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