Collapsible Summicron, how radioaktive is it again...?

[Helinophoto]

Hi

Just purchased a beautiful specimen of the old screwmunt Summicron:
http://www.ebay.com/itm/282097550920

I plan to use it on a iiif I also just bought:
http://www.ebay.com/itm/152368074971

It's a little radioactive (beta and gamma, which gamma is the one being emitted out of the lens), but how much really?

There is one guy that tried measuring the activity (albeit on the surface), but I cannot interpret those numbers.



Anyone with knowledge that know what values are actually measured here?

Apparently 1 Sievert (new unit) equals 100 RAD (old unit), so if the values on the surface are in millisieveterts, it should be pretty much safe from any distance. (Inverse square law)

The yellowing can be corrected by using UV-light.

Anyone with knowledge on this? (I only found a few old threads on photo.net)

 

[Soeren]

It is very dangerous, send it to me and Ill dispose of it correctly
Just dont eat it and youll be fine.

http://camerapedia.wikia.com/wiki/Radioactive_lenses

 

[guangong]

One advantage of these lenses is that for b/w photography the discolored glass never needs a yellow filter.

 

[removed account4]

hi guangong

i was thinking of something more practical, "nightlight" and ez way to make a hard boiled egg

 

[Helinophoto]

Haha ^^

But the numbers on the Geiger-meter, anyone know what those values were...?

 

[~andi]

The last physics lecture I heard is 20 years back but afaik those are CPM (counts per minute, cp. https://en.wikipedia.org/wiki/Counts_per_minute). The number of atoms the counter detected to have decayed in a minute. There's no direct conversion to Sievert. I reckon, you could very roughly extrapolate a value if you know the sensitivity of the probe, the exact elements it is calibrated to as well as a whole lot other properties of the emitter you are measuring (e.g. composition, type of radition reception e.g. through skin, lungs, etc...., i'm sure there are more properties).

TLDR: he video is nice for show effect, but the number don't tell you much, other than that something is going on beside the usual background radiation. I bet that holds true for measuring a banana as well (I wouldn't swallow it though, unless I knew it's going to be out again in a few hours )

Andi

 

[Helinophoto]

Ah......yeah, I googled it now, seems that a conversion to actual SI-values are usually done by knowledge of the equipment, radiation-type (and other factors) and then somewhat averaged into SI.

I just find that a bit funny, I see videos from Chernobyl all the time, where people are measuring mSV/h from objects, with small gadgets, all the time, so I thought this was something similar. ^^

I really don't think the lens(ses) are dangerous, but I would love to know the actual mSV-values at the surface of the lens.
So much actually, that I am thinking about getting in touch with the local university, or the "radiation-authorities", to get a proper measurement, just for the fun of it ^^

 

[Sirius Glass]

You could use it to keep your hands warm. Or since any radiation is so low, you can enjoy the lens. If it really bothers you, send it to me and I will deposit it in a toxic waste dump.

 

[Theo Sulphate]

Bananas, brick buildings / houses, and airplane flights probably expose you to similar amounts of radiation as the lens.

Basically, nothing to worry about.

From 2010-2013 I had about a dozen CT and PET scans (many magnitudes more radiation than your lens) and observe how rational I am. In fact, I can press most of the frets on a guitar simultaneously with my 36 fingers.

"A little radiation never hurt anyone." - me

 

[Saganich]

The meter count was 5796 CPM (counts per minute), which roughly translates to roughly 0.003 uCi (microcuries) of activity. The Geiger counter used is about 3-15% efficient for the energy range. I'll measure mine when I get home. I have a calibrated ionization chamber good for dose rates. The surface dose rate if I recall correctly is about 0.5 mR/hr or about 5 micro-Sieverts/hr. I keep mine in a shielded box due to film proximity. I measured the dose rate to my eye when mounted on my MP and that was background.

 

[removed account4]

Bananas, brick buildings / houses, and airplane flights probably expose you to similar amounts of radiation as the lens.

Basically, nothing to worry about.

From 2010-2013 I had about a dozen CT and PET scans (many magnitudes more radiation than your lens) and observe how rational I am. In fact, I can press most of the frets on a guitar simultaneously with my 36 fingers.

"A little radiation never hurt anyone." - me

pernicious lies i tell you !
hey wait a minute, you aren't J. Frank Parnel from RepoMan are you ?
i heard people self-combust all the time too !
( don't worry, i won't look in the trunk )

 

[Helinophoto]

The meter count was 5796 CPM (counts per minute), which roughly translates to roughly 0.003 uCi (microcuries) of activity. The Geiger counter used is about 3-15% efficient for the energy range. I'll measure mine when I get home. I have a calibrated ionization chamber good for dose rates. The surface dose rate if I recall correctly is about 0.5 mR/hr or about 5 micro-Sieverts/hr. I keep mine in a shielded box due to film proximity. I measured the dose rate to my eye when mounted on my MP and that was background.

Very informative, thanks =)

Although, I seem to see that the max-measurement on the front of the lens is 15.60 at 0:32 (with *1000 in the top left corner), but I suppose that would be 0.009 uCi or something like that.

It's just interesting stuff ^^
I keep my film-stash in the next room (freezer) from my cameras, but how thick led-lining would you recon is required to shield the top (and possibly sides) ?

I have 40 rolls of neopan 1600 that may be a bit sensitive, and I might move soon, so things can change.

Would be fun to make a real sweet box ^^

 

[Soeren]

Since the decay chain from thorium emits alpha and beta radiation you are good with a piece of paper Those are only dangerous in direct contact like if ingested/inhaled and are stopped within few cm in air. Alpha wont penetrate a piece of paper and beta will be stopped by glass or at last something in that category.

 

[Fraunhofer]

Soeren, this would be true if all decays were to the ground state, but they are not and so there are gammas from de-excitation. In particular thallium-208 produces an energetic 2.6MeV gamma, which requires quite bit of shielding. BTW, this line is used to identify thorium ore. In any case, I doubt there is enough intensity to fog film.

And just to come back to the OP: there are not enough of those either to be harmful, assuming your not carrying it in your pant pockets 24/7.

 

[Saganich]

Very informative, thanks =)

Although, I seem to see that the max-measurement on the front of the lens is 15.60 at 0:32 (with *1000 in the top left corner), but I suppose that would be 0.009 uCi or something like that.

It's just interesting stuff ^^
I keep my film-stash in the next room (freezer) from my cameras, but how thick led-lining would you recon is required to shield the top (and possibly sides) ?

I have 40 rolls of neopan 1600 that may be a bit sensitive, and I might move soon, so things can change.

Would be fun to make a real sweet box ^^

Yes, that looks correct. I measured the lens last night with a calibrated ionization chamber. The dose rate was approximately 7.0 uSv/hour (0.7 mR/hr) on surface. The energy range barely exceeded 300keV. These are all the low energy gammas, conversion electrons and x-rays in the decay chain above. The majority of energy deposited in the glass is from alphas, which don't escape the glass which is why the glass changes color. The betas (if they escape at all since most are too low energy) won't travel more than 20cm.

For shielding I use 2.5mm thick lead sheet in the top and bottom of a stainless steel jar, like the old jars in doctors offices, to get the count rate close to background in the draw below where I keep my bulk loaders, which I don't use anymore anyway. No worries about film in the freezer in the next room. I would dismount the lens if the neopan 1600 is kept in the camera for extended times.

 

[kb244]

I wonder if that explains the slight yellowing I have on my Industar-61L/D (L for Lanthanum).

 

[Soeren]

Soeren, this would be true if all decays were to the ground state, but they are not and so there are gammas from de-excitation. In particular thallium-208 produces an energetic 2.6MeV gamma, which requires quite bit of shielding. BTW, this line is used to identify thorium ore. In any case, I doubt there is enough intensity to fog film.

And just to come back to the OP: there are not enough of those either to be harmful, assuming your not carrying it in your pant pockets 24/7.

The decay chain is offcource simplified but still the conclusion remains.
I would worry more about radon from the underground etc.
If one really is affraid of radiation he/she should live a couple of meters beneath the water surface in a construction made of e.g. pre WWII ship steel

 

[kb244]

The decay chain is offcource simplified but still the conclusion remains.
I would worry more about radon from the underground etc.
If one really is affraid of radiation he/she should live a couple of meters beneath the water surface in a construction made of e.g. pre WWII ship steel

I figured nearly all radioactive lens (radioactive from manufacturing, not from being contaminated after the fact), is at best a conversation piece in regards to it's radioactivity. IF they were high enough to cause a concern, there would be restriction of their sales in today's market.

Though I learned something interesting about eyepieces being radioactive, didn't know those existed.

 

[Rrrgcy]

A gentleman about a year and a half ago offered a couple of Summicron lenses on Evilbay of which he measured their radioactivity out to the front (the rear was much much less - since he had the equipment available to measure it (his old profession involved the equipment). In the listings he did explain a bit of history to the lenses, the elements, and his method and equipment measuring same. He Really seemed to want to be responsible. He did warn on about the higher one, especially. I bid then rethought retracted and didn't buy. I wrote to him and he did confirm based on the readings that given standard tables the higher one was the equivalent of about seven chest X-Rays per exposing your hand to the front for a sec or so. He didn't object to my retracted bid, especially after I mentioned I had children who would be learning on some older leica iiif's. I suspect you'd need to have someone credibly measure the output of radiation w the appropriate equipment, then check to see exactly to what the output equates. I don't think I'd want several Xrays exposure each moment I handled the front end, which I suspect would be often enough in using it.

 

[Helinophoto]

Yes, that looks correct. I measured the lens last night with a calibrated ionization chamber. The dose rate was approximately 7.0 uSv/hour (0.7 mR/hr) on surface. The energy range barely exceeded 300keV. These are all the low energy gammas, conversion electrons and x-rays in the decay chain above. The majority of energy deposited in the glass is from alphas, which don't escape the glass which is why the glass changes color. The betas (if they escape at all since most are too low energy) won't travel more than 20cm.

For shielding I use 2.5mm thick lead sheet in the top and bottom of a stainless steel jar, like the old jars in doctors offices, to get the count rate close to background in the draw below where I keep my bulk loaders, which I don't use anymore anyway. No worries about film in the freezer in the next room. I would dismount the lens if the neopan 1600 is kept in the camera for extended times.

Thank you very much for your information, always good to have some actual figures to relate to

I will probably make a simple box and line it with a little lead, then I can store the lens where ever (and, as others have mentioned, it's a cool conversation-piece), I will cover the lead with plastic, as this, in practice will be more hazardous than the radiation, I figure

 

[kb244]

A gentleman about a year and a half ago offered a couple of Summicron lenses on Evilbay of which he measured their radioactivity out to the front (the rear was much much less - since he had the equipment available to measure it (his old profession involved the equipment). In the listings he did explain a bit of history to the lenses, the elements, and his method and equipment measuring same. He Really seemed to want to be responsible. He did warn on about the higher one, especially. I bid then rethought retracted and didn't buy. I wrote to him and he did confirm based on the readings that given standard tables the higher one was the equivalent of about seven chest X-Rays per exposing your hand to the front for a sec or so. He didn't object to my retracted bid, especially after I mentioned I had children who would be learning on some older leica iiif's. I suspect you'd need to have someone credibly measure the output of radiation w the appropriate equipment, then check to see exactly to what the output equates. I don't think I'd want several Xrays exposure each moment I handled the front end, which I suspect would be often enough in using it.

Yeesh... is that even commercially sellable ? (not sure what the guidelines are in specific countries). If someone said a lens was radioactive I wouldn't assume much more than background radiation, but several chest x-rays, brought up to your head every time you shot? (though much more so on your hands/fingers as you operated/handled it)

 

[Saganich]

Yeesh... is that even commercially sellable ? (not sure what the guidelines are in specific countries). If someone said a lens was radioactive I wouldn't assume much more than background radiation, but several chest x-rays, brought up to your head every time you shot? (though much more so on your hands/fingers as you operated/handled it)

Time and distance are often overlooked in radiation. A typical total dose from a chest x-ray ranges from 2 - 6 mrem (or 20 - 60 uSv) depending on the procedure (Health Physics Society Website). The dose RATE from my lens (front element) is measured to be 0.7 mrem / hour on surface flat energy response. In order to receive 1 chest x-ray worth of dose from my front element I would have to put it to my chest for between 3 and 8 hours. In order for one chest x-rays worth of dose (2mrem) to be received by a shooter the dose rate at the back of the camera would have to be: 2mrem/3 seconds per shot x 3600 sec/hr = 2400 mrem/hr. I can say that this is very very unlikely from a natural source material in glass.

 

[kb244]

Time and distance are often overlooked in radiation. A typical total dose from a chest x-ray ranges from 2 - 6 mrem (or 20 - 60 uSv) depending on the procedure (Health Physics Society Website). The dose RATE from my lens (front element) is measured to be 0.7 mrem / hour on surface flat energy response. In order to receive 1 chest x-ray worth of dose from my front element I would have to put it to my chest for between 3 and 8 hours. In order for one chest x-rays worth of dose (2mrem) to be received by a shooter the dose rate at the back of the camera would have to be: 2mrem/3 seconds per shot x 3600 sec/hr = 2400 mrem/hr. I can say that this is very very unlikely from a natural source material in glass.

Though the person I quoted said it was the equivalent of 7 (seven) chest x-rays for the one on sale.

 

[Helinophoto]

Was it a Summicron, or an Ektar or something else?

I have seen discussions on lenses (WWII stuff) that seemingly emits more that the Summicron.

 

[bdial]

You may be thinking of an aero-Ektar, which is quite a large beast. There may be enough glass in its radioactive element to make an entire Summicron.

My M4/collapsible Summicron is sitting idle and loaded, and has been for a while. I guess I'll see what happens, I'm not expecting any issues.