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Yashinon 50 1.4 dx radioactivity some datas and calculations
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PostPosted: Tue May 31, 2016 5:49 am    Post subject: Yashinon 50 1.4 dx radioactivity some datas and calculations Reply with quote
I have just bought the yashinon 50 dx 1.4, chrome type.

Nice buy but I ran across a youtube video showing its radioactivity level (1359 nSv/h) at a close distance

https://www.youtube.com/watch?v=Alt6fmXgyik

1359 nano Sievert will convert to 1.359 Micro Sievert per hour. (http://www.convertire-unita.info/Convertitore-di-unita-di-misura.php?tipo=dose-di-radiazione)

The lens will keep me company for all my day trips, residing in my side bag along with a praktica bc20 with zoom.

At work it will stay at a certain distance from me (couple meters).

basically I will be walking all the day with the lens close to my body.

Now this website gives a nice warning for living at 1 Micro Sievert per hour (http://radiationsurvival.blogspot.it/)

"0.001 Sv/hr or 1 mSv/hr or 1,000 uSv/hr [Total: 24 mSv/day] = Long term danger and long term cancer risk"

The lens will dangle at close distance from my body, in my side bag, for an approximate 2 -4 hours a day, so I can safely assume to receive an average 2 - 3 Micro Sievert a day, five days a week, plus I will keep it in my living room or other house room permanently.

Frankly speaking to me this is too much and it will ever be.

I have just had my second post cancer surgery and I'm ever at risk of developing new one.


PostPosted: Tue May 31, 2016 6:48 am    Post subject: Reply with quote
It should not be an issue as the radiation is mostly alpha. When you mount the lens on a camera, most of the alpha radiation are blocked by the camera.
https://www.reddit.com/r/askscience/comments/11bj4s/thorium_coated_camera_lens_what_kind_of_danger_is/c6l0xsp

Metal caps which helps to block the radiation too.


PostPosted: Tue May 31, 2016 7:51 am    Post subject: Reply with quote
A former radiologist and oncologist wrote me back just now

"Lei scrive di essere un paziente oncologico. Il dato da solo dice poco. Per darle un esempio, gli accertamenti radiologici indispensabili in tante situazioni di malattia espongono il malato a dosi significative di radiazioni. Nessuno si sognerebbe di mettere in dubbio gli enormi vantaggi clinici derivanti dall'impiego di tecniche diagnostiche. I dati che lei riporta relativi al Torio presente negli obiettivi che impiega non dovrebbero preoccuparla. Nelle cantine delle nostre case è presente il Radon: tutti da tempi immemorabili siamo esposti alle radiazioni del fondo naturale. Continui a fare buone fotografie. XX"

Synthesis: do not worry. Go on taking good pics.

Ok. Now it's really cleared. Do not ask me for a deal on the yashinon, as long as you are not sending me c7y 35 1.4 in a fair exchange ...


PostPosted: Tue May 31, 2016 7:52 am    Post subject: Reply with quote
calvin83 wrote:
It should not be an issue as the radiation is mostly alpha. When you mount the lens on a camera, most of the alpha radiation are blocked by the camera.
https://www.reddit.com/r/askscience/comments/11bj4s/thorium_coated_camera_lens_what_kind_of_danger_is/c6l0xsp

Metal caps which helps to block the radiation too.


Good idea. Will machine a cap with my friend. Ty


PostPosted: Tue May 31, 2016 8:18 am    Post subject: Reply with quote
It's a lovely lens, and I'm using mine more and more over other good 50's that I've got.

You could carry it in one of those bags used to carry film through airport X Ray machines, that would probably be enough of a barrier when it's in your bag.


PostPosted: Tue May 31, 2016 8:28 am    Post subject: Reply with quote
Lloydy wrote:
It's a lovely lens, and I'm using mine more and more over other good 50's that I've got.

You could carry it in one of those bags used to carry film through airport X Ray machines, that would probably be enough of a barrier when it's in your bag.


It may be overkill, but I cut up into pieces one of those old lead film bags and lined a couple of lens cases with it for carrying around old Yashinons. I think that solves any possible issue of proximity to something radioactive while the lens is not on the camera.


PostPosted: Tue May 31, 2016 9:03 am    Post subject: Reply with quote
good suggestions. health is not a secondary issue as we are constantly exposed to many sources of pollutants, so reducing them is ever good.

i was thinking of coating a lens cap with lead salvaged from somewhere.

lead is easily melted and hammered to shape with basic tools, than it can be glued to an ordinary cap


PostPosted: Tue May 31, 2016 9:49 am    Post subject: Reply with quote
Melting lead may be more of a health risk than the radioactivity! Could be fun though.


PostPosted: Tue May 31, 2016 11:17 am    Post subject: Reply with quote
You don't need one made of lead. Aluminum caps like this one Click here to see on Ebay should stop most alpha and beta radiation.


PostPosted: Tue May 31, 2016 12:06 pm    Post subject: Reply with quote
calvin83 wrote:
It should not be an issue as the radiation is mostly alpha.

Sorry, that's wrong. Thorium itself mainly emits alpha particles, but after 10-15 years the gamma radiation from daughter ions gives more counts than the original alpha particles.

Usually the radiation close to lens is quite high (several hundred times background), but in >5m distance it is lower than background.

Since even small additional radiation levels (e. g. doubling of the background) are scientifically linked to higher cancer risk, keeping a hot lens close to your body is definately a risk.

I keep my "hot" lenses in a safe distance from my living/sleeping rooms, and i use them only for a very short time.

(i have studied chemistry, and i made my master thesis at an analytical laboratory which was using radiochemical methods at that time)

Stephan


PostPosted: Tue May 31, 2016 12:14 pm    Post subject: Reply with quote
stevemark wrote:
calvin83 wrote:
It should not be an issue as the radiation is mostly alpha.

Sorry, that's wrong. Thorium itself mainly emits alpha particles, but after 10-15 years the gamma radiation from daughter ions gives more counts than the original alpha particles.

Usually the radiation close to lens is quite high (several hundred times background), but in >5m distance it is lower than background.

Since even small additional radiation levels (e. g. doubling of the background) are scientifically linked to higher cancer risk, keeping a hot lens close to your body is definately a risk.

I keep my "hot" lenses in a safe distance from my living/sleeping rooms, and i use them only for a very short time.

(i have studied chemistry, and i made my master thesis at an analytical laboratory which was using radiochemical methods at that time)

Stephan


The physician I quoted in italian has had a long experience in oncology, treating people with radiotherapy. He claims that radon in houses will be a comparable threat, and says that oncological patients are often exposed to massive doses of x rays.

Said that I would still gladly examine your references, a single physician is often not enough in delicate matters.

Creating a small lead shield would be easy for me, I only do not have a geiger to check the shielding effectiveness but I might find one.


PostPosted: Tue May 31, 2016 12:45 pm    Post subject: Reply with quote
Just how close was the 'close distance'?
Radiation dose follows the inverse square law (like flash photography).
So if 'close' was 1cm increasing the distance to 2cm the dose rate would be 1.4/4 = 0.35 mSv/h. I'd expect your average distance in photographic use to be over 4cm (less than 0.1mSv/h)...

With alpha radiation anything denser than a vacuum will further attenuate the dosage (Typical alpha range in air is 3cm).
Your camera bag or any lens cap or camera body will reduce it very significantly, and make it pretty much impossible to detect the alpha radiation.

Even if you are touching the glass of your lens, typical low energy alpha particles are stopped by 0.04mm of dead skin. The 2+ layers of dead skin over your body is enough to mitigate external exposure from this.

BTW average annual dosage from NATURAL radioactivity across the UK is 2.2 mSv, in Cornwall it's ~7mSv.


PostPosted: Tue May 31, 2016 1:29 pm    Post subject: Reply with quote
DConvert wrote:
Just how close was the 'close distance'?
Radiation dose follows the inverse square law (like flash photography).
So if 'close' was 1cm increasing the distance to 2cm the dose rate would be 1.4/4 = 0.35 mSv/h. I'd expect your average distance in photographic use to be over 4cm (less than 0.1mSv/h)...

With alpha radiation anything denser than a vacuum will further attenuate the dosage (Typical alpha range in air is 3cm).
Your camera bag or any lens cap or camera body will reduce it very significantly, and make it pretty much impossible to detect the alpha radiation.

Even if you are touching the glass of your lens, typical low energy alpha particles are stopped by 0.04mm of dead skin. The 2+ layers of dead skin over your body is enough to mitigate external exposure from this.

BTW average annual dosage from NATURAL radioactivity across the UK is 2.2 mSv, in Cornwall it's ~7mSv.


I think the core of the question lies in gamma rays. The movie shows that the lens emits mostly betas and gamms, and they can damage tissue and body.

gamams are also known as x rays.

It must be stablished if keeping the lens within 10 cms from skin for around three hours a day, five days a week, can be harmful in the long haul (I carry my notebook camera everywhere, and use betetr gear only on weekends and holydays or at night.)


PostPosted: Tue May 31, 2016 3:58 pm    Post subject: Reply with quote
Even though the seller admits this device isn't accurate to scientific standards, it might be good enough to monitor any increase in dosage due to close proximity to the lens, and the effectiveness of anything used as a barrier while a lens is being carried.

http://www.anythingradioactive.com/smart-geiger-FSG01



.


PostPosted: Tue May 31, 2016 9:45 pm    Post subject: Re: Yashinon 50 1.4 dx radioactivity some datas and calculat Reply with quote
bghomofaber wrote:
I have just bought the yashinon 50 dx 1.4, chrome type.

Nice buy but I ran across a youtube video showing its radioactivity level (1359 nSv/h) at a close distance

https://www.youtube.com/watch?v=Alt6fmXgyik


Having just watched the video (youtube is blocked at work) I can't see where you get your dose rate measurement. '1359nSv/h'
The read out of the Geiger counter is in counts per second. The relationship between CPS & dose is rather complicated - IIRC it requires knowledge of the active isotopes (or at least the energy & type of the activity) neither of which was shown in the video.

All radioactive lenses I've ever heard of are radioactive due to 'Thoria' a thorium based ceramic that increases refractive index and decreases dispersion in the glass. Nearly all natural thorium is Th232 an alpha emitter (with very long half life).

There will be other types of radioactive decay going on as the daughter nucleotides decay, but most of these are also alpha decays (four beta, and six alpha decays takes thorium to stable lead). This other radioactive decay can only happen after the daughter nucleotides have formed (via decay of an atom of the original thorium), Half-lifes of all the daughter nucleotides are minuscule compared to the initial Thorium (The longest lived daughter has a half life less than 1 billionth of Thorium 232) so it's decay is very much the rate limiting step...

Last edited by DConvert on Tue May 31, 2016 9:57 pm; edited 1 time in total


PostPosted: Tue May 31, 2016 9:52 pm    Post subject: Re: Yashinon 50 1.4 dx radioactivity some datas and calculat Reply with quote
DConvert wrote:
bghomofaber wrote:
I have just bought the yashinon 50 dx 1.4, chrome type.

Nice buy but I ran across a youtube video showing its radioactivity level (1359 nSv/h) at a close distance

https://www.youtube.com/watch?v=Alt6fmXgyik


Having just watched the video (youtube is blocked at work) I can't see where you get your dose rate measurement. '1359nSv/h'
The read out of the Geiger counter is in counts per second. The relationship between CPS & dose is rather complicated - IIRC it requires knowledge of the active isotopes (or at least the energy & type of the activity) neither of which was shown in the video.

All radioactive lenses I've ever heard of are radioactive due to 'Thoria' a thorium based ceramic that increases refractive index and decreases dispersion in the glass. Nearly all natural thorium is Th232 an alpha emitter (with very long half life).

There will be other types of radioactive decay going on as the daughter nucleotides decay, but most of these are also alpha decays (four beta, and six alpha decays takes thorium to stable lead). This other radioactive decay can only happen after the daughter nucleotides have formed (via decay of an atom of the original thorium), Half-lifes of all the daughter nucleotides are minuscule compared to the initial Thorium so it's decay is the rate limiting step...


Data are given in the Camerapedia article. Source not quoted.

"Yashinon-DX 50mm f/1.4 (Yashica) (Measured at 1359 nSv/h)
Yashinon-DX 50mm f/1.8 (Yashica) YouTube
Yashinon-DS-M 50mm f/1.4 (Yashica) (Measured at 572 nSv/h)
Yashinon-DS-M 50mm f/1.7 (Yashica) (Measured at 798 nSv/h) https://www.youtube.com/watch?v=Z2DyF3o7hQ4"

from

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

the fourth quote from Camerapedia's article point to the same series of video from which I took the one about the yashinon 1.4


PostPosted: Tue May 31, 2016 11:43 pm    Post subject: Reply with quote
I posted this a while back, the link is now dead, but the text is copied, and you can view the link at the internet archive if needed.

Quote:
http://www.hps.org/publicinformation/ate/q1356.html
Quote:
Category: Doses and Dose Calculations — External dose calculations

The following question was answered by an expert in the appropriate field:
Q
Several photography websites I read have had questions in their forums about radioactive materials in camera lenses. I know that lanthanum and thorium (possibly other elements) have been used to modify the index of refraction for glass used in some lenses. Others have raised concerns about safety when using the lenses. Can you provide a discussion of the problem and an assessment of the risk to users?
A

There is a partial answer to your question in the "Historical" category of "Ask the Expert."

Perhaps the best single source of information is the Nuclear Regulatory Commission's NUREG-1717, "Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials." When the NRC website is back up and running, this report should be available at http://www.nrc.gov/reading-rm/doc-collections/nuregs/. Refer to pages 3-285.

Some general points:

The radioactive component of the lenses is 232Th (and its decay products). The thorium was added to increase the index of refraction of the lenses. The fact that thorium is radioactive was irrelevant. The first use of thoriated lenses seems to date from the late 1930s or WW II. The production of thoriated camera lenses seems to have ceased in the late 1980s. Lenses used by the military are particularly likely to be radioactive. Almost everything is radioactive to some extent. I have seen ordinary glass double the counts on a Geiger Muller detector because of the potassium content of the glass (most glass will not do this however).

One tissue of concern might be the lens of the eye—the potential consequence being cataracts. The development of cataracts as a result of a radiation exposure is referred to as a "nonstochastic" or "deterministic" effect. This means that in order for cataracts to occur, an effective threshold dose must be exceeded. The minimum dose at which cataracts can occur is a few hundred rad (the threshold depends to some degree on the type of radiation).

Thorium emits alpha, beta, and gamma radiation. For cameras employing thoriated lenses, only the gamma rays result in a dose to the lens of the eye (or any other part of the body for that matter).

The major determinant of the dose to the lens of the eye is the length of time the photographer is holding the camera up to the head. As an example, the dose rate near the viewfinder of an old Pentax camera of mine (Super Takumar lens) is roughly 100 microrad per hour—approximately ten times background. In other words, looking through the viewfinder of this camera for one minute results in the same dose that I receive every ten minutes when not using it. I would have to hold this camera up to my eye for several million hours to exceed the threshold dose for cataracts. For what it's worth, I have never had any qualms about using the camera and to my knowledge, there have been no documented cases of individuals developing cataracts as a result of cameras employing thoriated lenses.

Other parts of the body might also receive an exposure, in particular the abdomen due to the camera hanging from the neck. NUREG 1717 reported an "effective dose equivalent" of 0.7 mrem per year to users of cameras employing thoriated lenses. This is the dose to the whole body that would carry the same risk as a specified dose to a single tissue or tissues (for example, the dose to the abdomen and eye). This 0.7 mrem is substantially less than 1% of the 300 mrem that we receive each year due to our exposure to background radiation.

Of significantly more concern is the possibility that the eyepiece itself employs a thoriated lens. This has been the case in some military devices and some unauthorized commercial devices. This is a much greater problem because of the proximity of the eyepiece to the eye and the fact that alpha and beta emissions now contribute to the dose. If the eyepiece is radioactive, the germinal cells of the cornea become the tissue of concern and the potential annual dose becomes quite high. NUREG 1717 discusses this in some detail. Fortunately, thoriated eyepieces are comparatively rare.

As an additional point of interest, it was not unusual many years ago (1940s) for photographers to employ a uranium-containing toner to tint photographic prints (Kodak made such a toner). These prints would be measurably radioactive.

References

Radiation Exposure of the U.S. Population from Consumer Products and Miscellaneous Sources. National Council on Radiation Protection and Measurements Report 95

Frame P, Kolb W. Living with Radiation—the First Hundred Years

Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials. NUREG-1717

Paul Frame, CHP, PhD


I originally posted this here: http://forum.mflenses.com/viewtopic.php?t=53099


PostPosted: Wed Jun 01, 2016 12:04 am    Post subject: Reply with quote
Another good read: http://www.orau.org/ptp/collection/consumer%20products/cameralens.htm

Quote:
Perhaps the greatest health concern is the potential for thoriated glass to be used in an eyepiece. This is not permitted by the regulations, but it has occurred. If the eye is positioned close to a thoriated eyepiece, the dose to the eye’s outer tissues can be substantial.

(Don't use thoriated lenses as loupes.)

Re: normal usage, not eyepieces:
Quote:
Measurements have indicated that the exposure rate at a depth of 10 cm in the body of an individual carrying a camera containing 0.36 uCi of thorium would be approximately 0.01 mrem/hr. Based on this value, NUREG-1717 calculated that a serious photographer might receive an annual exposure of 2 mrem. This assumed that the photographer carried the camera 30 days per year and for 6 hours per day. They also estimated an exposure of 0.7 mrem per year for an average photographer. If the camera lens contained the maximum permitted concentration of thorium (30%), NUREG-1717 estimated that the aforementioned annual doses could triple.


PostPosted: Wed Jun 01, 2016 3:15 am    Post subject: Reply with quote
There are some thorium coated lenses for infrared photography. These lenses are pretty safe when the coating is not damaged. However, one need to pay attention when the coating is damaged or the lens is broken. See here http://www.crystran.co.uk/userfiles/files/zinc-selenide-znse-thorium-coatings.pdf .


PostPosted: Wed Jun 01, 2016 5:24 am    Post subject: Reply with quote
Well, even if the camerapedia article is correct, my estimate of 2-3 microSievert a day of radiation would not mean much according to this source

"10 μSv – The average radiation you received today"

http://www.pureearth.org/blog/radiation-101-what-is-it-how-much-is-dangerous-and-how-does-fukushima-compare-to-chernobyl/

what a pity. I already have some kilos of lead in my basement, close to vice, hammers and tools.

building a special lead cap would have been interesting.

In any case I just understodd how to adjust perfectly the rf of my isolette 3, collimating back the rf into a cristal clear unit.

Feel better

calculating 3 mSievert a day, in a year it would be 3 times 5 (days I carry the lens a week) times 52 (week in a year) that would be around 780 msievert a year. (MICRO Sievert)

A single mammogram gives a woman 3.000 microSievert, and each woman has usually one per year withi normal brest cancer prevention checks

Last edited by bghomofaber on Wed Jun 01, 2016 9:08 am; edited 1 time in total


PostPosted: Wed Jun 01, 2016 9:07 am    Post subject: Reply with quote
As usually, latin m is not the greek mi .... what is dangerous are millisievert (latin m symbol). Microsievert are 1000 times less, an order of magnitude less. They are written with the greek letter mi as a symbol

And on the web mi comes out pretty badly, easy to take it ofr an m for me, we used to write it correctly with a long leg as it has to be back in time....


PostPosted: Wed Jun 01, 2016 10:33 am    Post subject: Reply with quote
Lloydy wrote:
Even though the seller admits this device isn't accurate to scientific standards, it might be good enough to monitor any increase in dosage due to close proximity to the lens, and the effectiveness of anything used as a barrier while a lens is being carried.

http://www.anythingradioactive.com/smart-geiger-FSG01


Had one of these for testing purposes. They are not sensitive enough for the measurement of low radiation levels and cannot detect alpha or beta radiation. I'm currently looking into buying a GQ GMC-320 or GQ GMC-300E, as they are much more sensitive, detect beta particles and are not that much more expensive.


PostPosted: Wed Jun 01, 2016 11:11 am    Post subject: Reply with quote
bghomofaber wrote:
As usually, latin m is not the greek mi .... what is dangerous are millisievert (latin m symbol). Microsievert are 1000 times less, an order of magnitude less. They are written with the greek letter mi as a symbol

And on the web mi comes out pretty badly, easy to take it ofr an m for me, we used to write it correctly with a long leg as it has to be back in time....


On the PC Alt+0181 usually works Ok for µ. I've often seen u used instead which is easily understood & not mistaken for any of the other prefixes.


PostPosted: Thu Jun 02, 2016 12:31 pm    Post subject: Reply with quote
And I was going to make an offer for your DX f/1.4.
Laugh 1
I'm not concerned over the radiation issue of these lenses. I have about a dozen radioactive lenses.
Yes, these thoriated lenses do emit alpha, beta and gamma. Alpha is no concern as it's blocked by the camera itself, or a lens cap.
Use some due diligence in storing them. I keep mine in the garage or in an aluminum case in the dining room.
I simply shoot as usual with them.

We get a greater dosage from other source in our lives than these lenses. The exposure from a number of transcontinental flights annually far exceeds what I will get from taking a few shots with these lenses.


PostPosted: Thu Jun 02, 2016 2:47 pm    Post subject: Reply with quote
WNG555 wrote:
And I was going to make an offer for your DX f/1.4.
Laugh 1
I'm not concerned over the radiation issue of these lenses. I have about a dozen radioactive lenses.
Yes, these thoriated lenses do emit alpha, beta and gamma. Alpha is no concern as it's blocked by the camera itself, or a lens cap.
Use some due diligence in storing them. I keep mine in the garage or in an aluminum case in the dining room.
I simply shoot as usual with them.

We get a greater dosage from other source in our lives than these lenses. The exposure from a number of transcontinental flights annually far exceeds what I will get from taking a few shots with these lenses.


If I ever get a glowing green nose I will send you for free.
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