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Radioactivity of old manual lenses
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PostPosted: Tue Jan 31, 2017 1:30 pm    Post subject: Reply with quote
Gerald wrote:
Think positive. Radioactive lenses are immune to fungus. Mr. Green

I wouldn't bet on that. I have seen all kinds of things growing in radioactive solutions. Smile


PostPosted: Tue Jan 31, 2017 3:01 pm    Post subject: Reply with quote
Gerald wrote:
Think positive. Radioactive lenses are immune to fungus. Mr. Green


If only that were true. My Aero Ektar had MASSIVE fungus. I think the fungi FEED on gamma radiation, becoming thereby even more voracious and destructive.


PostPosted: Tue Jan 31, 2017 3:35 pm    Post subject: Reply with quote
guardian wrote:
Gerald wrote:
Think positive. Radioactive lenses are immune to fungus. Mr. Green


If only that were true. My Aero Ektar had MASSIVE fungus. I think the fungi FEED on gamma radiation, becoming thereby even more voracious and destructive.



ooooh! Now there's an idea for a creepy sci-fi film!


PostPosted: Tue Jan 31, 2017 4:33 pm    Post subject: Reply with quote
Miles Teg wrote:
Gerald wrote:
Think positive. Radioactive lenses are immune to fungus. Mr. Green

I wouldn't bet on that. I have seen all kinds of things growing in radioactive solutions. Smile
Rapidly mutating and turning into horror movie monsters......


PostPosted: Tue Jan 31, 2017 4:49 pm    Post subject: Reply with quote
guardian wrote:
Gerald wrote:
Think positive. Radioactive lenses are immune to fungus. Mr. Green


If only that were true. My Aero Ektar had MASSIVE fungus. I think the fungi FEED on gamma radiation, becoming thereby even more voracious and destructive.


It seems you've got a point here!

"Recent data show that melanized fungal species like those from Chernobyl’s reactor respond to ionizing radiation with enhanced growth." Surprised

source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2677413/


PostPosted: Fri Feb 16, 2018 2:09 pm    Post subject: Reply with quote
so essentially, what you're saying is that all the lenses whose readings are highlighted in white are NOT radioactive and that the measurement is only the background measurement? Sorry, I'm a noob at this. Thanks in advance.


PostPosted: Fri Feb 16, 2018 3:19 pm    Post subject: Reply with quote
I'm really wondering if people who are scared about the possible radioactivity of their lenses do also check their place of living.

There are regions (even within Europe), where the natural radiation level is 5 times higher compared to other ones; and I'm not talking about the cernobyl surroundings.

That's approximately the same effect like what is coming from these thorium lenses.

The big difference is that you are only affected some minutes during photography, whereas if you are living in higher radiation areas you're affected 24 hours per day. Consequently the place of living may be much more dangerous than any "radioactive" lens.

However, if somebody wants to get rid of such radioactive lenses, I'll take them all. Wink


PostPosted: Fri Feb 16, 2018 4:14 pm    Post subject: Reply with quote
I think comparing them to common activities helps put them into context.
The highest value on the table was around 2.5µSv/h, this is HALF that received from cosmic radiation when flying at 12,000m (typical airline).

As a photographer I might pend more time within 1cm of a lens than I do flying, but on average I very much doubt it.
Most of the lenses are closer to everyday life. On average in the UK people are exposed to ~2.5mSv a year (half of this being from natural radon gas, which is more than 5 times more concentrated in Cornwall than where I live). This average works out as 285nSv/Hr fairly typical for these lenses.


PostPosted: Fri Feb 16, 2018 4:17 pm    Post subject: Reply with quote
darcymiller wrote:
so essentially, what you're saying is that all the lenses whose readings are highlighted in white are NOT radioactive and that the measurement is only the background measurement? Sorry, I'm a noob at this. Thanks in advance.


Welcome darcymiller


PostPosted: Fri Feb 16, 2018 5:17 pm    Post subject: Reply with quote
darcymiller wrote:
so essentially, what you're saying is that all the lenses whose readings are highlighted in white are NOT radioactive and that the measurement is only the background measurement? Sorry, I'm a noob at this. Thanks in advance.


Welcome to the forum
Sorry I missed this.

From the values shown the white values are within the range of background readings taken at the site so certainly not what most people would consider radioactive.
If the where measured with more sensitive equipment in a very well shielded position some radiation would almost certainly be detectable - but this is the case with just about everything. Their values are well below what you'd get for bananas or crushed brazil nuts....


PostPosted: Fri Feb 16, 2018 5:46 pm    Post subject: Reply with quote
DConvert wrote:
I think comparing them to common activities helps put them into context.
The highest value on the table was around 2.5µSv/h, this is HALF that received from cosmic radiation when flying at 12,000m (typical airline).

To be fair, the highest value I got with calibrated equipment was 37 µSv/h, directly at the mount. But even that is nothing to worry about, as long as your are not carrying your lens for prolonged time as some sort of crazy monocle, balls-attached jewellery or very weird sex-toy...


PostPosted: Fri Feb 16, 2018 5:58 pm    Post subject: Reply with quote
tb_a wrote:
I'm really wondering if people who are scared about the possible radioactivity of their lenses do also check their place of living.
There are regions (even within Europe), where the natural radiation level is 5 times higher compared to other ones; and I'm not talking about the cernobyl surroundings.
That's approximately the same effect like what is coming from these thorium lenses.
The big difference is that you are only affected some minutes during photography, whereas if you are living in higher radiation areas you're affected 24 hours per day. Consequently the place of living may be much more dangerous than any "radioactive" lens.


Well, radiobiology would probably disagree a bit. A constant exposure of low-level radioactivity likely stimulates repair systems, such as DNA-repair enzymes, therefore causing so-called "hormesis" effects. This has been seen in the Taiwan study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2477708/), where exposed people had significantly reduced cancer death and congenital malformation incidence rate. According to this and other studies, the biopositive annual dose might actually be around 50 and 100 mSv/year. So a short-term mid level exposure is probably more dangerous as long-term low-level exposure, even though the accumulated dose might be similar or even higher in the low-level exposure. Bu in any case, none of the lenses will causes anything different that low-level exposes, even when used as intended, even daily.


PostPosted: Fri Feb 16, 2018 5:59 pm    Post subject: Reply with quote
darcymiller wrote:
so essentially, what you're saying is that all the lenses whose readings are highlighted in white are NOT radioactive and that the measurement is only the background measurement? Sorry, I'm a noob at this.
Hello. here is a maintained list of known radioactive lenses (and some lanthanum ones): http://camerapedia.wikia.com/wiki/Radioactive_lenses. So check the list and provided you have a "mainstream"/consumer grade lens, you should be safe.


PostPosted: Sat Feb 17, 2018 5:31 am    Post subject: Reply with quote
Miles Teg wrote:
tb_a wrote:
I'm really wondering if people who are scared about the possible radioactivity of their lenses do also check their place of living.
There are regions (even within Europe), where the natural radiation level is 5 times higher compared to other ones; and I'm not talking about the cernobyl surroundings.
That's approximately the same effect like what is coming from these thorium lenses.
The big difference is that you are only affected some minutes during photography, whereas if you are living in higher radiation areas you're affected 24 hours per day. Consequently the place of living may be much more dangerous than any "radioactive" lens.


Well, radiobiology would probably disagree a bit. A constant exposure of low-level radioactivity likely stimulates repair systems, such as DNA-repair enzymes, therefore causing so-called "hormesis" effects. This has been seen in the Taiwan study (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2477708/), where exposed people had significantly reduced cancer death and congenital malformation incidence rate. According to this and other studies, the biopositive annual dose might actually be around 50 and 100 mSv/year. So a short-term mid level exposure is probably more dangerous as long-term low-level exposure, even though the accumulated dose might be similar or even higher in the low-level exposure. Bu in any case, none of the lenses will causes anything different that low-level exposes, even when used as intended, even daily.


That's indeed quite interesting as I have already seen studies (in my country as well) that have shown exactly the contrary; i.e. a direct link between higher natural radiation dose and higher cancer rate shown on geographical maps.
Like it's the case with many other studies as well the intention behind any study undertaken may also play a role....
However, I'm not an expert. Nevertheless I've also seen contradictory studies, particularly when it comes to higher radiation rates in the surroundings of nuclear power plants and the rate of leukemia rate (affected children) in that areas; i.e when the study was ordered by the operator or even the government it showed a different result to what was found by health care organisations.
Anyway, I prefer to live in a low level radiation area with a relatively low average cancer rate which is both proven by simple statistics.


PostPosted: Sat Feb 17, 2018 5:49 am    Post subject: Reply with quote
The only practical consideration I have for radioactive lenses applies to my usual practice of fixing cast away lenses with issues. I'd prefer not to remove or work around thoriated elements and risk chipping or fracturing them in the process.


PostPosted: Sat Feb 17, 2018 9:52 am    Post subject: Reply with quote
y wrote:
darcymiller wrote:
so essentially, what you're saying is that all the lenses whose readings are highlighted in white are NOT radioactive and that the measurement is only the background measurement? Sorry, I'm a noob at this.
Hello. here is a maintained list of known radioactive lenses (and some lanthanum ones): http://camerapedia.wikia.com/wiki/Radioactive_lenses. So check the list and provided you have a "mainstream"/consumer grade lens, you should be safe.


I don't find that listing as useful as the one at the start of this thread. Many of the lenses have no indication of the relative amount of radioactivity and with multiple testers there's no way to account for variations in background/equipment. Of those where rates are given some are low enough I would consider them not really radioactive. (At work we use twice background as the trigger level of not totally decontaminated).

Compiling data from multiple sources like this certainly widens the scope, but the data has to be treated with a much wider degree of caution.


PostPosted: Sat Feb 17, 2018 9:36 pm    Post subject: Reply with quote
Gerald wrote:
guardian wrote:
Gerald wrote:
Think positive. Radioactive lenses are immune to fungus. Mr. Green


If only that were true. My Aero Ektar had MASSIVE fungus. I think the fungi FEED on gamma radiation, becoming thereby even more voracious and destructive.


It seems you've got a point here!

"Recent data show that melanized fungal species like those from Chernobyl’s reactor respond to ionizing radiation with enhanced growth." Surprised

source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2677413/


No joke. The darn fungi all but destroyed the rear element of my lens!

As I have written elsewhere on this forum, the only radiation that really matters or amounts to anything with these lenses is the gamma radiation. They are hot gamma radiation sources up close. But back off not very far at all from your lens and the level of gamma radiation quickly falls almost to background levels.

Problem is, the fungi are living right ON the surface of the lens. They are receiving the maximum dose of gamma radiation available. And they LOVE it!!


PostPosted: Mon Feb 19, 2018 8:26 am    Post subject: Reply with quote
tb_a wrote:
That's indeed quite interesting as I have already seen studies (in my country as well) that have shown exactly the contrary; i.e. a direct link between higher natural radiation dose and higher cancer rate shown on geographical maps.

It is not really clear whether radiation has a linear dose-respose effect on the human body or if the effect, at least the initial part (in the low level area) of the curve is either steeper of flatter. There is even no consensus whether there is a threshold. I am no expert as well, but from what I remember, the three (and probably more) models basically either predict a higher detrimental effect of low level radiation, a linear relationship or even a lower effect including hormesis. Based on my personal experience, I tend to think that most of the biological systems rather respond in a non-linear fashion, e.g. as seen in many drug dose-response curves. Combined with the inevitable background radiation, which was likely higher in the advent of life on this planet, I would tend to think that it makes more sense that low-level radiation has a lower risk, maybe even with a "hormesis zone". The Taiwan study is not the only one on this side of the spectrum. Ramsar in Iran has a background level of radiation 10-50 times higher as compared to Europe, and yet, cancer incidence rates are lower than in the rest of the country.
tb_a wrote:

Like it's the case with many other studies as well the intention behind any study undertaken may also play a role....
However, I'm not an expert. Nevertheless I've also seen contradictory studies, particularly when it comes to higher radiation rates in the surroundings of nuclear power plants and the rate of leukemia rate (affected children) in that areas; i.e when the study was ordered by the operator or even the government it showed a different result to what was found by health care organisations.

In any case, if the initiator of the study has some kind of agenda, it can easily affect the outcome. And the "fallout" from psychological stress as a result of "fear tactics" is probably a force to be reckoned with, similarly as if we would loosen the control of how to deal with radiation, radioactive waste etc. But quite a few people keep this irrational fear, probably due to nuclear weapons and the NPP disasters, but don't really care about all the chemicals in their food, their cloth etc. And they seem to have no issues with this kind of cognitive dissonance, which I don't really get, because if one thing is great about radioactivity: it can be easily measured.
tb_a wrote:

Anyway, I prefer to live in a low level radiation area with a relatively low average cancer rate which is both proven by simple statistics.

I can understand this, but I also think that statistics apply to a number of events and might not predict the outcome of a single event, e.g. the individual human being. Wink


PostPosted: Mon Feb 19, 2018 10:20 am    Post subject: Reply with quote
DConvert wrote:
I don't find that listing as useful as the one at the start of this thread. Many of the lenses have no indication of the relative amount of radioactivity and with multiple testers there's no way to account for variations in background/equipment. Of those where rates are given some are low enough I would consider them not really radioactive. (At work we use twice background as the trigger level of not totally decontaminated).

Compiling data from multiple sources like this certainly widens the scope, but the data has to be treated with a much wider degree of caution.
Well, nobody stated the data were obtained in a scientific way.

There was no re-testing, no consistent (let alone calibrated) equipment was used, no exact distance setup, etc. Same goes for the lens specification - sometimes there are many different optical designs of a single lens. Some of them may use radioactive elements, some of them may not.

Sure, it would be nice to create a unified testing methodology and send all lenses of the world to a single lab which would measure them but... you know.

The list serves more like a note saying there is a certain possibility a listed lens might be more radioactive than those not listed Wink


PostPosted: Mon Jun 15, 2020 5:20 pm    Post subject: Some points Reply with quote
(I did not read _all_ the responses, so maybe some of this has been mentioned already.)

According to what little research I've done, thoriated glass gives off primarily alpha radiation and I don't think the detector you mentioned (Radex RD1503) detects alpha radiation, so I don't know what you detected, but it is unlikely to be alpha radiation from thoriated lens elements.

Alpha radiation (from what I read) is easy to block, so a lens cap, a lens case, a backpack, should all provide adequate protection while carrying thoriated lenses around or sleeping with them in the room with you.

I collect only Super-Takumars, and from what I can tell (based only on research, I have no alpha radiation detector) perhaps five examples contain thorium:
Three examples of the Super-Takumar 50 / 1.4 -- 7-element variant, serial numbers greater than about 1.5 million
Two examples of the Super-Takumar 55 / 1.8 -- serial numbers greater than about 1.5 million
The consensus is that the early 50 / 1.4 (8-element) never has thorium, and early 55 / 1.8 (below about 1.5 million) do not.

Two other (unsubstantiated) rules of thumb concerning Super-Takumars are:
Focal lengths longer than 55mm do not contain thorium (though I have seen someone say that his 85 / 1.8 does).
Only the "faster" (more expensive) versions were thoriated -- the 55 / 1.8 , not the 55 / 2 ; the 35 / 2 , not the 35 / 3.5 ; etc.


PostPosted: Tue Jun 16, 2020 4:12 am    Post subject: Reply with quote
HI all,

I have a number of these radioactive lenses. It is my opinion that the low level of alpha radiation present in photographic lenses is of little consequence to health.

Most precautions regarding low-level radiation exposures are based on a theory known as the linear hypothesis, which supposes a linear relationship between radiation exposure and negative health effects (ie. various cancers, etc.) developing over time. This linear relationship supposes that even the smallest of doses will result in some small, non-zero number of health effects. In fact, many physicists believe that such a non-threshold linear relationship is not a valid model of real world health physics. Their theories propose some low threshold of exposure at and below which there are no health effects at all. Furthermore they speculate that even if small amounts of cell damage do occur due to low levels of radiation exposure, our cells have the ability to repair these slight inconsistencies. Lastly most radiological models of exposure are based on whole body exposures, and the kind of exposure we might receive from the alpha particles escaping from a thoriated camera lens would be much more localized than a standard whole body dose.

If you would like a really practical explanation of radiation health physics and the linear hypothesis, check out Chapter 4 of Physics and Technology for Future Presidents By Richard A. Muller.

My background is in mechanical engineering, but I sometimes teach a physics for non majors course at the College I work at, and Muller's book is the text I use.

All the best,

paul
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