Radioactive camera lenses

[Manfred M]

From the 1940s through the 1970s some lens manufacturers used radioactive thorium oxide in some lens elements. The material was used to produce high refractive, low dispersion glass. The biggest offender appears to have been Eastman Kodak.


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

[William W]

Thank you for the link. It appears a comprehensive list and there are useful links contained in it.

From the 1940s through the 1970s some lens manufacturers used radioactive thorium oxide in some lens elements. The material was used to produce high refractive, low dispersion glass. The biggest offender appears to have been Eastman Kodak.

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

Probably depends how we define "biggest offender" - the author of the article cites Kodak and quantity/production: but it is probable that many (mostly all) of those lenses were never removed from their cameras and are now not used, possibly destroyed.

On the other hand, a good proportion of the Pentax (Takumar) 50mm lenses employed Thorium 232 and other naughties.

These Pentax lenses are still in circulation now and some are reasonably sort after. I see quiet a few used as "legacy" lenses today and for several years previous, by folk who have no idea of the lens's composition.

This video is old, but it is thorough and I have used it several time as part of my reference material for my talks on this topic.

WW

[Black Pearl]

Just picked one up the other week that I need to sort.

I got a Pancolar 50mm f1.8 for a couple of quid as it has bright yellow glass and a sticky aperture. I have read you can 'bleach' the yellow out with certain LED lights and a friend is pretty good at stripping down lenses and cleaning out the old grease to free them up. I'll put a post up when I'm finished showing the before and after.

[Shadowman]

I at first only read the thread and not the link, I was going to comment on the amount of dosage associated with the lens and read that it is similar to the amount we receive through other functions (airport xrays, dental xrays). One thing that seemed an odd statement is the amount of damage it can do to the eye when in actuality it is the skin or hand that would come in most contact with the lens. Granted we probably never wash our hands after handling a lens and no telling where we put our fingers after touching electronic equipment.

[pnodrog]

I at first only read the thread and not the link, I was going to comment on the amount of dosage associated with the lens and read that it is similar to the amount we receive through other functions (airport xrays, dental xrays). One thing that seemed an odd statement is the amount of damage it can do to the eye when in actuality it is the skin or hand that would come in most contact with the lens. Granted we probably never wash our hands after handling a lens and no telling where we put our fingers after touching electronic equipment.

There is no contamination - a bit like when your hands feel heat from a fire but they have no fire on them. The dose seems overstated. If film (much closer and longer proximity to the source) was constantly subject to worrying levels of radiation it would start to fog. I would not sleep clutching such a lens every night but with normal use it is not hazardous. Wearing an old style luminous watch is probably more of a concern.

In a radio chemistry lab you used to wear a film badge (about a credit size strip of film in light tight cover and with a thin lead shield on one end, no shield in the mild and from memory a copper shield on the other end). The film is processed once a month and any fogging indicates exposure and the difference under the shields gave a clue as to what type of radiation.

[tao2]

As the (former) owner and user of a number of thoriated lenses, ah did a fair bit of research on them and nothing raised any fear . I sold those lenses - Super Tak f1.4/50mm., Fujinon f1.4/50mm., MC Rokkor PG f1.2/58mm, not because they may have been radioactive (they were) but because of the ridiculously high prices that eBayers, with more money than sense, were willing tae pay, at certain times.

As far as Taks and and other lenses go re. radiation, wrap them in printing paper, put them in a cardboard box - yer protected. The yellow/brown discolouring can be removed but ye need consistent, warm/hot sun, say on a window ledge(window open) for 3/4 weeks. Or, a uv lamp - about a week, depending on the lamp. The only caveat ah've ever seen was - don't hold one of these lenses tae yer eye for regular, lengthy periods. That is, just the lens, if it's attached tae the camera, then ye have a large screen of metal and plastic between yer eyes and the lens.

Most experts say that, yer lens would have tae be smashed and the powdered thorium (if any) would have tae be ingested immediately or rubbed in the eyes, in order tae enable the possibility of radiation infection. Since the thorium was actually in the glass,as part of manufacturing the lens, seems unlikely tae me. Ah remember one scientist saying that if ye taped a thoriated lens tae yer belly for 5/6 hours a day, or licked a lens for a couple of hours, every day, then, ye would get around the same dosage of radiation as a resident in Scandinavia who receives around twice the world average because of where they live (background radiation).

Ah limited myself tae licking ma lenses, only for one hour per day...

PS Ah also have lenses containing Lanthanum, despite reports tae the contrary, this is not radioactive. Jist can't get rid of this cough, though...

PPS
Just noticed this fae John (Shadowman)

when in actuality it is the skin or hand that would come in most contact with the lens

the radiation is so weak that your skin acts as a barrier to it.

[Manfred M]

Looking at it from the back of the lens (i.e. from the photographer holding the camera); the alpha particles would have been stopped by the shutter (even a piece of paper blocks alpha particles), beta particles would have been blocked by a metal shutter and / or the back plane of the camera (that puts the Pentax and Leica M users at a disadvantage, as these cameras had cloth shutters; I don't know the specifics of the other brands ). So gamma emissions would have been the only issue from a photographer's standpoint.

Of course, had it been a problem; the film (which is sensitive to radiation) would have been fogged as it sat right behind the shutter. I guess that was one advantage of the relatively slow films of the day; they were less sensitive to radiation, but it still suggests that the dosage was quite low.

[Saorsa]

Tao2

You really need something with the lanthanum lenses.

[Wideopeniris]

I dont think there is any need for alarm. Radioactive lenses are safe to use - the radiation rates at more than 1m distance are well below background rates. I wouldn't sleep with one under my pillow, but for normal use there is little risk.

Thoriated lens elements used in lenses like the Aero ektars and other eastman kodal lenses produce alpha beta and gamma radiation types due to the long thorium decay chain. Alpha emitters are considered most dangerous as ingested material causes tissue damage. But the alpha emitters in the glass are bound in the glass matrix and are not free to be ingested. If you ground the glass and ate it then maybe you might cause a radiation problem :-)

The only area of concern is microscope and telescope eyepieces that are used at close proximity to the eyes for long periods. But on a camera most of the radiation is shielded by the camera anyway.

You might be surprised how common lenses with radioactive elements are - some Canon FD and Pentax lenses from the 80's have some level of radiation. I found my Pentacon 6 mount Zeiss Flektogon 50mm was hot too. Smaller lenses for 35mm format are usually hard to detect even close up due to the small amount of glass with thorium content.

As someone once said - any worth-while pursuit involves a degree of danger - the elements with this property all enable faster or wider angle lenses, so its a small thing to put up with to use these lenses' unique properties :-)

Kevin.

[Helly123]

Thank you for the link. It appears a comprehensive list and there are useful links contained in it.



Probably depends how we define "biggest offender" - the author of the article cites Kodak and quantity/production: but it is probable that many (mostly all) of those lenses were never removed from their cameras and are now not used, possibly destroyed.

On the other hand, a good proportion of the Pentax (Takumar) 50mm lenses employed Thorium 232 and other naughties.

These Pentax lenses are still in circulation now and some are reasonably sort after. I've read a lot about this and tried to find more information using essays on scientists & inventors. I see quiet a few used as "legacy" lenses today and for several years previous, by folk who have no idea of the lens's composition.

This video is old, but it is thorough and I have used it several time as part of my reference material for my talks on this topic.

WW

I think now it is already possible to treat the concept of radioactivity more calmly, since it still surrounds us to some extent.

[Manfred M]

I think now it is already possible to treat the concept of radioactivity more calmly, since it still surrounds us to some extent.

The reason the lens makers used glass with radioactive elements in the formulation was to achieve specific refractive indices for the glass. Glass chemistry has advanced a lot over the past 60 - 80 years.

The problem with ionizing radiation is that the effects are cumulative, so eliminating these sources makes sense. Some of the nasty side effects of these glass types include decreasing opacity of the lens element and discolouration of the optical component. I have not examined one of these lenses myself and am basing my comments on things I have read about them.

[William W]

I think now it is already possible to treat the concept of radioactivity more calmly, since it still surrounds us to some extent.

I am not sure of your meaning and your message in that comment.

Perhaps you could expand, please?

As mentioned, "The problem with ionizing radiation is that the effects are cumulative".

I think the 'concept' of radioactively should be addressed objectively and with scientific method: "calmly" vs. "heated emotion" doesn't come into that equation.

I think that the commentary above, is mostly an objective discussion, and, it was also calm.

WW

[DanK]

Indeed. The more we are exposed to, the more we should be concerned about additional exposure.


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[Ken MT]

If you are concerned about radiation don't go out in the sun, or take long distance flights.

[revi]

Indeed, there are a lot of other radiation sources out there (granite, anyone?)

Also, those lenses were used for film photography. Film fogs when it's irradiated :
- X-ray photo's are taken at doses that are considered relatively harmless and used to be taken on film
- and there was the idea that the X-ray scanners at airports were bad for film (another use where the dose
for the passenger should be harmless...)

So I don't think normal use of a lens with some thorium in it is will have any significant effects.

Oh, and while thorium is an alpha radiator, that type of radiation won't even leave the lens...