Super-Tak 50/1.4 and X-ray emissions

I'm not concerned with alpha-beta, but has anyone measured the X-ray

emissions from one of these lenses? I just got a rather yellow one;

it's sitting wrapped in foil on the window sill right now, and I'm

wondering how much it emits at X-ray energy levels. If I understand

correctly it doesn't emit a whole lot of gamma.

 

I read somewhere that it emits the same as a transatlantic flight.

How much is that? Is that mainly cosmic or solar radiation? I

understand solar photonic radiation is mainly at gamma levels while

cosmic radiation is X-ray? (Actually, I don't have a clue what makes

me think that but I'll leave it here anyway.) Is this a nightside or

dayside transatlantic flight it's equal to? At what latitude and time

of year? Route? Direction?

Economy or business class?

What diffeence does it make? Don't carry it around in your underwear 24/7 and you don't have to worry about it. A gadget bag is enough to block those evil rays.

I never can understand why people buy 1.4 standard lenses. I think I've shot at that aperture about once or twice in my life. The focussing is hardly any brighter than a 1.8 and less if you have a bright screen camera like a Fuji ST. And you have to lug around that extra weight all the time. Personally, I'd steer clear of any lens that had yellowed or browned glass.

I thought X-Rays are gamma radiation? That is, very short wave ultra violet light. The AMA

just came out with a study saying there is no "Safe minimum" X-Ray exposure. Something to

think about next time the dentist wants to zap your brains out.

 

I've heard the Super Tak can be hot, but not as bad as some of the APO Lanthar large format

lenses. No way to tell unless you take it to a college science lab and get it tested. Why do

people buy 1.4 lenses? Why do they fall in love? Enjoy food? Tell jokes?

Maybe it's so they can take photos like the one below in low light without a flash.<div></div>

"I've heard the Super Tak can be hot, but not as bad as some of the APO Lanthar large format lenses."

 

Well, if this is more than an urban legend, the Super Tak will have very, very little radiation. The Lanthar lenses were made with lanthanium alloy glass, and lanthanium is a substitute for thorium which was used for some time to make high refraction index glass. Lanthanium contains much less of an radioactive isotope than thorium did. I have severe doubts whether lanthanium glass has any noticeable radiation at all, and if the Super-Tak has less...

 

BTW I read in a (professional) book about optics that lanthanium glass was introduced in the mid-50s, so I think there is hardly any lens made after this date containing thorium glass which was already known for radiation back then.

 

Another BTW: did anyone talking about "radioactive lenses" ever made an actual test with a radiation tester on these lenses?

Old Lanthanum glasses, though used Lanthanum Oxide to make the glasses there was always residual Thorium in them as the Lanthanide elements occur together in their mineral. So, it is just not a matter of a particular radio isotope of Lanthanum being the source.

 

I have heard the sound and seen the dial move on a counter when one of my XR-Heligon lenses (Rodenstock collimating lenses, large and heavy glass) was measured. It is real for that lens. The same guy who did the checking also informs me that the old 35mm f/1.4 Nikkor has radioactive glass elements.

Hi,

this topic has been discussed quite a while ago in an oly mailing list. I wrote something there, but the archives are inaccessible at the moment. So I have to use my memory. I own a Zuiko 50/1,4, which has some radioactive element. I took the opportunity (I am a radiochemist)to take a gamma ray spectrum of the lens and found the whole decay chain of thorium. The total activity and dose rate was extremly low.If I recall my posts correctly, I did say almost the same as Glen said: don?t carry the lens close to your reproductive organs all day, and don?t dissolve the glass and drink the liquid....

In my opinion, there is absolutely no reason for concern (although I cannot figure out real numbers at the moment).

 

Gamma and x-ray is the same type of radiation, only discerned by energy. x-ray is a low energy type of gamma radiation.

If you google for "radiation exposure airplane", you will find lots of information, e.g. http://www.hc-sc.gc.ca/hecs-sesc/rpb/cosmic.htm

 

Rainer

"I never can understand why people buy 1.4 standard lenses. I think I've shot at that aperture about once or twice in my life."

 

Because they want one stop more exposure than they get with a F2 lens?<div></div>

I'm guessing that damage to individuals using items with residual radioactivity is unmeasurable. However, the story may have been different among workers in industries producing the items. I think the problem was documented among watch makers who handled radium for painting watch faces. Don't know about lens makers.

Russ:

 

You wrote, "Something to think about next time the dentist wants to zap your brains out." Well think about this. If your dentist finds a small correctable problem with that x-ray, don't you think it might be a fair trade-off? Enjoy your meal with a new set of dentures.

If you don't like radiation exposure, quit flying. Absolutely the largest preventable source of ionising radiation exposure to humans in the world today -- probably excluding cancer patients getting radiation therapy.

Might also want to avoid travel in southern Chile and Argentina where people are getting reluctant to let their kids out in the daylight because of the ozone hole. Another source of exposure is the accumulation of radon gas in improperly vented house foundations. Of course, since these hazards are cumulative, the answer may be to just not live too long.

Very interesting and informative thread. I have one of the old single coated Zuiko 1.4 lenses.

It sure takes good photos. Frank, I agree and let my dentist zap my brains out with X-Rays

the other day. I like candy and taking pictures way too much to worry about radiation!

 

If anyone wants to see a good movie about what thorium can do to people, rent an English

film from 10 years back called "The Young Poisoner's Handbook". This guy was real, and he

worked in a top secret UK lens plant where thorium was used for aerial recon lenses. You can

guess the rest....

My dear friend, let me tell you honestly:

living means living perilously...

 

My personal translation of the german sentence by Erich Kaestner:

 

Mein lieber Freund , ich sag es Dir ehrlich:

Leben ist immer lebensgef�hrlich!

Rainer

Russ, if that's the case I've seen on History Channel, it was thallium, not thorium, he used. It's much more toxic than thorium and not significantly radioactive; also rare enough that few physicians or medical examiners would recognize the symptoms. As I recall, he was caught by old fashioned police methods, before they even realized it was thallium poisoning knocking off the people he killed.

 

And yes, the Super Takumar 1.4/50 is radioactive, at least in certain serial numbers. I have one of those, and have recently cleared (most of) the yellowing with a sunbath.

 

My take on the radiation is simple: it doesn't fog film through a cloth shutter, even with weeks of exposure; therefore, if I don't sleep with it under my pillow or use it for a loupe with my eye right against the rear glass, it's unlikely to do me as much harm as the radon evolved from thorium in the soil and bedrock here in North Carolina.

 

If you smoke, don't even begin to worry about the level of radiation from any commercially sold lens, unless it was in Chernobyl on the Very Bad Day. Likewise if you ride a motorcycle, climb mountains, or work as a firefighter, policeman, or cab driver. If you fly regularly, as already suggested, you'll take a lot more dose of more damaging radiation from spending a few hours a week way up high above the Earth's natural shielding than you would from years of keeping a radioactive Super Takumar in your camera bag or on the camera.

Yeah, I saw that thallium episode thing. Not the same thing as thorium. I ran across a web site once that had very interesting and thorough dope on radioactive lenses. Can't remember where it was but in a nutshell, as I said, just keep it out of your pants and don't worry about it. There are even government regulations regarding the manufacture of these things. Over so many units of what ever it is, ya can't make 'em like that.National security, health and all that, ya know.

X-rays are emitted when electrons in a atom fall to a lower energy level. Gamma rays originate in the nucleus of an atom. The products of radiactive decay may be alpha particles (helium nuclei), beta particles (high speed electrons) or gamma rays. I don't remember the decay sequence for thallium or thorium, but if the lens is a gamma emitter, wouldn't that fog the film? If the element is a beta emitter the metal in the camera will stop it. Alpha particles can be stopped by paper or most anything else. If an internal element is radioactive, then it's doubtbul any alpha radiation would escape.

Mike,

you are totally correct. Indeed, most of the isotopes in the decay chain of thorium ( forget thallium, please) emit characteristic gamma-rays. But the total dose is so low, that you will not notice any fogging during normal film use. Perhaps , if you leave a film for years without moving the frame .

I'm not asking whether there's risk, whether in anyone's opinion it's high or low, or whether it's higher or lower than something else -- but exactly what's emitted and how much so I can make my own decisions. What's pretty clear from reading the stuff I could find is that none of the information is designed for a person to make a health risk assessment. For instance, X-rays are 2-3X as mutagenic as gamma, which is many orders of magnitude more mutagenic than alpha even if the latter is in the form of inhaled gas. Yet there is only a single measurement (usually expressed in mSv, millisievert, or sometimes cSv) for dosage. Doesn't matter what kind of radiation it is. Similarly, the MPD set by the government is 1mSv annually for non-radiation workers. (I suspect that's actually 1cSv, or 10mSv.) But 1mSv of X-ray is mutagenically comparable to 2-3mSv of gamma, or maybe several Sv of alpha. (Several Sv of X-ray would kill a human within seconds.) Not only that, but the effects are completely different -- a whole Sv of alpha would more likely cause severe surface burns, not internal organ failure (other than indirectly). The exception is alpha in the lungs, but even that is far less mutagenic than even gamma by several orders of magnitude.

 

Yet e.g. the air industry applies the same 10mSv MPD limit. On the ground we get on average (USA) 0.27mSv from radon alpha, at 30kft that's replaced with 0.27mSv cosmic X-rays. Over the pole on a transatlantic flight it's 3X that. It doesn't take a genius to recognize that the health risk isn't comparable just because the dosage numbers are the same. One site mentioned a limited study that showed airline pilots, despite being generally healthier and less prone to cancers than normal, have 4-5X as many cases of certain forms of Leukemia, 2X certain brain cancer, and various other illnesses typically contracted from radiation exposure. Curiously, this was hypothesized by one writer as not caused by cosmic radiation but radar (i.e. microwave).

 

A chest CT scan on an adult was listed by one document as 5mSv. A head area (e.g. dental) X-ray as 1.5mSv. These are X-rays, not gamma, and positively not alpha which wouldn't even work. With 2-3 images made each time, that's equivalent to 400 and 100 hrs of flying, respectively. A 75000 mi annual frequent flyer flies about 250 hours, and a commercial pilot about 1000 hours. Clearly one can't just say a dental X-ray is equivalent to flying unless we're talking about airline pilots.

 

I also don't think cosmic radiation or a lens element, or some such is a strong enough X-ray/gamma source to fog film.

 

It's also not reasonable to say a risk should be ignored because it's lesser than something else; the sum is always greater and risks additive, sometime they grow geometrically (when multivariate). Also, when assessing risk the probability needs to be multiplied by impact and these negative expectancies accumulated.

 

I think it would be far more useful if radiation dosage were measured in terms of "mutagenic power" rather than the number of decay events or some such. (The latter has clearly its uses, but doesn't seem to me to be directly related to health effects.)

 

Anyway, it seems to be a difficult area to assess, and apart from the juvenile penis jokes isn't one many like to talk about.

I wrote "On the ground we get on average (USA) 0.27mSv from radon alpha, at 30kft that's replaced with 0.27mSv cosmic X-rays". By this I meant that .27mSv of radon alpha is relatively harmless compared to .27mSv of cosmic X-ray. Yet purely by the numbers there wouldn't seem to be any difference.

To understand the difference between thorium and thallium you should download this little song by Tom Lehrer and get a laff....... (with apologies to Gilbert and Sullivan)

 

http://chemistry.ucd.ie/lab/Humor/tom-lehrer-the-elements.mp3

Jan, visit Michael Briggs' site http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html