File :-(, x, )
Anonymous
I had read about some 50/1.4 Pentax that had a look similar to what gets called the "Leica Glow," and had been trying to figure out what it was. One-hundred something dollars all told plus film sounded pretty good for something that sounded like it would be a great conversational portrait set up.

I had been looking at just K-mount lenses; in another recent thread, someone pointed to me that it was a screwmount. I found it: it's the SMC Takumar 50/1.4 in the M42 mount. Perfect. Get myself a Spotmatic and go to lovely, glowly town.

But here's the problem: it doesn't just glow in the image. It turns out it contains radioactive thorium elements. There's a lot of advice about sticking it in far corners of the house when you're not using it and being fine. The problem is that I live in a small studio apartment; I'd never be more than maybe eight yards from the lens. Does anyone know if I have any options?

TL;DR how do I shield myself from Thorium lens elements in a small apartment?
>> Anonymous
the most common misconception about radioactive materials is that they act like basically a big powerful microwave, zapping out cancer energy to anyone in a five mile radius. while this is true for gamma radiation, alpha and beta radiation are particle-based. they literally shoot out radioactive particles. Beta decay is slightly more dangerous: it has a 12-foot range in the air, and it can penetrate human skin. Alpha decay is relatiely safe: it can't penetrate human skin and is too heavy to travel through the air. Just don't swallow it or get it in any cuts.

which is to say, you'll be fine. thorium emits alpha radiation. If you're feeling nervous, wear latex gloves, but otherwise just make sure you wash your hands after handling the lens, and try not to feel up the front element too much.
>> Anonymous
>>95893
The stuff I read said it also put out gamma radiation that only a few feet of lead or a good distance would help. Which did seem like a lot... I didn't think gamma was that bad, but I'm not a physicist.

Are there any nuclear physicists on /p/?
>> Anonymous
>>95899
I wouldn't be worried if it were just alpha and beta, but I found a few places saying it gave off gamma, too.

The thorium elements are towards the rear, I think.
>> Anonymous
>>95898
You *can* get busted for carrying a radioactive lens over the border; I know of at least one guy who had problems with getting a package of lenses through customs because it contained a radioactive Takumar.
Anyway, that doesn't seem much of a problem. Pack it in a thick case, or just buy a non-radioactive lens for such occasions, as they're quite cheap nowadays.
>> Anonymous
>>95902

well, technically all radioactive material emits gamma radiation, since it's most often a byproduct of alpha and beta decay. but i seriously doubt that thorium emits enough gamma radiation to be of any concern, which is to say that you're getting the same dose of gamma radiation just from walking outside or smoking a cigarette.
>> Anonymous
You'll be fine.

Just think of all the alpha radiation you get from just visiting /p/. Speaking of which, where is Butterfly right now?
>> Anonymous
>>95911
I see what you did there.
>> Anonymous
>>95911
haha oh wow.
>> Anonymous
>>95911
I'm actually an A100 owner myself and I think Butterfly is actually quite reasonable and sane. I just couldn't avoid the gag ;)
>> BlackAdder !!bSWRwu/NqzQ
>>95921

Lies. All Sony Alpha owners are clearly mad as a barrel of strawberries. It must be all that radiation. It causes some kind of brain fever.
>> BlackAdder !!bSWRwu/NqzQ
>>95895

On the other side of the coin, if you sleep with it nestled against your crotch you'll get a free vasectomy with your lens. Help prevent any unwanted sprogs from turning up in years to come.
>> ac !!VPzQAxYPAMA
>>95945
Might leave a few sperm alive, though, but mutated. So he might have a monsterbaby. Or a superhero.
>> Butterfly !xlgRMYva6s
>>95911
hah i lol'd.

I was out shooting (rifles not cameras)
>> Anonymous
>>95983
You lie!

You were out detonating dirty bombs... that emit only alpha radiation! Terrist!
>> BlackAdder !!bSWRwu/NqzQ
>>95952

I fail to see the downside in this plan.
>> I||ICIT
>>95899
>>95905
QFT

i remember my physics teacher talking about the different radiations.

alpha is pretty much harmless stuff and as mentioned above can barely penetrate skin so i doubt it could even penetrate the casing of the lens...
if your worried about radiation in a lens, i sure hope you changed out your old smoke alarms for the new ionisig ones....

also another note i remeber seeing about these thorium lenses is that over time the lenses go yellow and to counteract this simply place it in the sun so the sun travels through it(on end) probably on a windowsill.
>> Anonymous
>>96049

Yes. Thorium undergoes alpha decay. Alpha particles can only penetrate a few inches of AIR, let alone anything else. They bouce off a single sheet of paper, or skin. The only way the thorium could hurt you would be if you ground up the camera and ate the bits.
>> Anonymous
http://cameras.alfredklomp.com/fed5/radiation/

It's about lanthanum, but close enough. Conclusion: it won't hurt you
>> Anonymous
>>96203
seconded. The research I did showed that the only health risks involved broken glass cutting the skin. Don't sleep with it and don't be shooting anything likely to explode (generally a good idea regardless of the lens) and you'll be fine.
>> Anonymous
Thanks everyone.

One more question: does anyone know of any M42 mount SLR with better viewfinder coverage? The Spotmatic only does 93%.
>> Anonymous
>>96226
And I have another one, actually: could people provide samples of different films, especially black and white ones?

Because all I know the "look" of is Velvia and T-Max 400.

Sorry for bumping my own thread up so much, but I figure someone else would be interested in this, too.
>> Anonymous
>>95892
wouldn't the radiation affect the exposure somehow, or create noise? or is it not enough?
>> des
>>96226
I don't think any of them have 100%. The absolute closest you'll get, afaik, is a Pentax LX with an m42 adaptor. That one's about 98, I think.
The spotmatic has a pretty craptastic finder, imo; you're better off with a fujica/mamiya/chinon. I've read a voigtlander bessa is fine too, but haven't poked one.
>> Anonymous
>>96305
No. Photographic film has very little sensitivity to light outside the visible range.

>>96293
Buy film, take pictures, see for yourself. Besides, black and white film isn't like color slide film. The look is highly dependent on processing factors, and the chemistry is not standardized like it is with E-6. One lab may use T-Max developer, one may use D-76, one may use Ilfotec, and they'll all produce different results.

>>96226
93% is perfectly useful unless you plan on doing photomicrography or some special application. Most people don't even look at the whole frame before they click the shutter in the first place. If you're really worried about it, you can always frame a little bit wide and if need be crop later.