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08-06-2012, 11:50 AM - 1 Like   #16
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I usually wear a bio-hazard mask and wrap myself in tinfoil (I duck tape the foil at the seams). This however doesn't work too well outside, the rays from the sun hitting the tinfoil really makes it hot and unpleasant - so if I am shooting outside with the tinfoil on I will first rub myself down with a nice layer of land-o-lakes butter, this helps sooth the skin and makes it easier to move around with the foil suit on...

08-06-2012, 11:52 AM   #17
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This has been discussed at length before. Link to a thread with another link to another thread regarding radioactivity in takumars. I'm posting the thread that links to the other thread because I think there's some fun/good discussion in it, too.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/184271-takumar...n-anxiety.html
08-06-2012, 12:08 PM   #18
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When the thorium decays, is the lens still radioactive?
08-06-2012, 12:15 PM   #19
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QuoteOriginally posted by iNicole Quote
When the thorium decays, is the lens still radioactive?
The half life of throium 232 is 14 billion years, which means in 14 billion years it will be half as radioactive as it was when new. Not entirely sure how much thorium is used in the average Super Takumar, so it is hard to judge how long it would take enough of it to decay to make it lower than the background level, but it is safe to say that 50 years won't make a difference.

Just a note, the longer the half life, the less dangerous an element is. That Americium 241 in your smoke detector has a half life of 432 years.


Last edited by elliott; 08-06-2012 at 12:31 PM.
08-06-2012, 02:25 PM   #20
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QuoteOriginally posted by iNicole Quote
When the thorium decays, is the lens still radioactive?
Just forget about it. These lenses are no more radioactive than the ground is naturally in many parts of the world, many of those places having thriving human populations with no adverse effects. No special measures are needed with these lenses. You could keep one in your pants pocket with no ill effects.

Seriously, if you want to worry about potential health threats, air pollution from coal plants and engine exhaust, and water pollution from agricultural fertilizers and pharmaceutical waste are both much more serious threats to you.
08-06-2012, 10:57 PM   #21
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I think you are exposed to more radiation by eating bananas which contain Potassium-40. (many other plant materials also contain this not just bananas)
Your body contains Carbon-14 which is also emits radiation, albeit at a slower rate. This is how Carbon dating works to estimate the age of organic materials.

The way I see it, the radiation from bananas ,,radiation from Takumars or consuming alcohol (radioactive or otherwise) might kill some brain cells but it kills the weakest ones first, so on average it makes you smarter.
08-06-2012, 11:07 PM   #22
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QuoteOriginally posted by steve1307 Quote
I think you are exposed to more radiation by eating bananas which contain Potassium-40. (many other plant materials also contain this not just bananas)
Your body contains Carbon-14 which is also emits radiation, albeit at a slower rate. This is how Carbon dating works to estimate the age of organic materials.

The way I see it, the radiation from bananas ,,radiation from Takumars or consuming alcohol (radioactive or otherwise) might kill some brain cells but it kills the weakest ones first, so on average it makes you smarter.
Does that mean bananas can lead to cancer?
I don't think killing brains cells would make you smarter, even if it was the weaker ones.. Or else inhaling gas would be a good thing. I think more brain cells the better.

Either way, I will be covering my SMC takumar 50mm 1.4 with aluminum foil, heard that aluminum foil can stop radiation. It will also a shield of protection against scratching the body of the lens!
08-07-2012, 12:51 AM   #23
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QuoteOriginally posted by elliott Quote
I think there is one Industar that uses lanthanum instead of thorium, but it is very uncommon to find, unlike the ubiquitous Super Takumar 50mm f1.4.
True, also with Zenitar M 1.7

Contrary to what some might assume about USSR, they were very safety oriented about consumer products and production itself (know this from personal experience).
They thought of Lanthanum as much safer alternative vs Thorium.

08-07-2012, 01:32 AM   #24
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QuoteOriginally posted by iNicole Quote
Does that mean bananas can lead to cancer?
I don't think killing brains cells would make you smarter, even if it was the weaker ones.. Or else inhaling gas would be a good thing. I think more brain cells the better.

Either way, I will be covering my SMC takumar 50mm 1.4 with aluminum foil, heard that aluminum foil can stop radiation. It will also a shield of protection against scratching the body of the lens!
I don't know, maybe I've eaten too many bananas, drunk too much alcohol and killed some of my better brain cells, if there were any good ones to begin with
I breath gas everyday. Usually a mixture of Nitrogen and Oxygen but in this office there is often some methane too..

In stopping radiation
alpha particles (helium nucleii) - can be stopped by a thin sheet of paper/ foil (or some distance in air)
beta particles (which are electrons) - can be stopped/absorbed by a thin sheet of aluminium plate
gamma rays (electromagnetic radiation) - can go through solid iron , humans etc etc without losing intensity.

Thorium-232 is an alpha emitter.


Just a tip: I keep old lenses in those neoprene beer bottle coolers. That would give a nice cylindrical shape and easier to wrap (roll up) in Aluminium foil, I think.

Wrapping bananas in foil and then eating them I wouldn't recommend Yuk
08-07-2012, 02:04 AM   #25
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QuoteOriginally posted by steve1307 Quote
In stopping radiation
alpha particles (helium nucleii) - can be stopped by a thin sheet of paper/ foil (or some distance in air)
beta particles (which are electrons) - can be stopped/absorbed by a thin sheet of aluminium plate
gamma rays (electromagnetic radiation) - can go through solid iron , humans etc etc without losing intensity.

Thorium-232 is an alpha emitter.
Just an observation I made : aluminum foil not even halved the radiation coming out of the rear of my 50/1.4.
My hypothesis: only the alfa parts near the surface of the glass can escape, but the gamma rays (although very little is emitted by the thorium) come from the total volume of the several thoriated elements.

Do I worry : no.
08-07-2012, 03:50 AM   #26
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QuoteOriginally posted by iNicole Quote
Hi,

So I'm planning to buy a radioactive lens. I know it sounds crazy.. but it's a fantastic lens in great condition, it's just radioactive. The last thing I want is for my family to be harmed from the radiation of the lens. Do you think lead foil will be enough to protect from radiation? Or do I need something thicker?

Thanks,
Nicole
There were a small number of lenses ever made with Thorium glass. The Tak 50/1.5 and 35/2 were among them. There is no personal risk. They do not seem to raise concern in airport security either. The main risk is the discolouration of the coating resulting from the radiation, for which there is a cure - UV light. Thorium glasses ahve now been banned, but that was because of the risk to workers in the factory where the glass was ground who could inhale the dust. Not good for them, just like asbestos is not good for people.
08-07-2012, 08:24 AM   #27
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Something I discovered today is this app actually will detect a radioactive lens, of course I wouldn't expect it to give a meaningful measurement. I was getting 30-40 counts per minute on my non-radioactive control lens and over 700 counts per minute on my known radioactive Super Takumar, so it can definitely be used to tell whether or not your lens is radioactive.
08-07-2012, 10:43 AM   #28
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QuoteOriginally posted by iNicole Quote
Does that mean bananas can lead to cancer?
No, it means that low levels of radiation are a normal part of our environment, and are harmless to us. We get more exposure from background radiation every day than you would get from using your lens periodically, even frequently. People get so silly about radiation, partly because of the media, and partly because it's invisible, but it's something that is present all the time, that either passes through us or gets absorbed by our skin all the time.

You do not need to take any additional precautions with thoriated glass, as long as you don't grind it up and eat it, and that would be a case of eating the glass and the chemical toxicity of the thorium, rather than the radiation it gives off. This is one of the big misunderstandings with radioactive metals in general. The places that the U.S. has shelled with DU artillery is a fine example. It's not the radiation causing deformities and cancers, it's the fact that uranium is highly poisonous to us. The radiation is incidental by comparison.
08-07-2012, 10:44 AM   #29
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QuoteOriginally posted by iNicole Quote
Yes I am talking about japanese lenses, I heard that they were quite expensive to make and each copy made the company loose money.


Okay, so you think that they won't be harmful at all? Or should I still protect myself from the lens when I'm not using it?
Don't worry, you can always file a class action lawsuit if anything goes wrong in the long run.
08-07-2012, 07:45 PM   #30
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QuoteOriginally posted by elliott Quote
Soviet lenses are not radioactive
The Industar 61 L/Z is highly regarded, inexpensive, readily available, and has Lanthanum glass.


Steve
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