Radioactive Lenses Part 2. How dangerous are they to use/store? Real world tests and conclusions. 

Every time I hear something about radiation, all I can think of is 3.6 roentgen and "not great, but not terrible"

I talked to scientists years ago about this and they said basically there's no worry about it and people who work as pilots or flight attendants will take higher doses of radioactivity than a user of a lens. So I guess if you are worried about being an airline pilot because you might get cancer, then don't use the lenses. Also it is more dangerous to live in certain parts of Colorado because the background radiation in some areas are actually causing cancer. The problem with thoriated lenses had to do with eye pieces for micro scopes and the people who would grind the glass manually were getting health problems, but users did not. Basically, don't break the glass or don't hold the glass right up to your eyeball and you'll be okay.

Hi, not particularly a photographer but I am an instrumentation engineer for astro & particle physics experiments (which basically means silicon sensor engineer). I broadly agree with your conclusions here in particular about safety. One point to add: the subject of radiation damage to silicon sensors is complex, but all imaging sensors absolutely do suffer from radiation degradation, this is the main thing that limits mission life in space telescopes, for example. Back when we used to use CCDs, the most important radiation damage mechanism was displacement damage to the silicon lattice caused by heavy (e.g. alpha, proton, neutron radiation) increasing charge transfer inefficiency over time. These sensors are less sensitive to so-called "TID" damage, which mainly comes from beta & gamma sources shifting the flat band of the MOS capacitor structures used in all (CCD and CMOS) imaging sensors. Modern CMOS sensors, due to not having to do so much charge transfer, are much more radiation hard from a displacement perspective on average, though their smaller pixel sizes cancels that out a little bit. In addition, modern thin-gate processes are a little more resistant to TID. Finally, in the case of modern sensors they are mostly back-illuminated, which again slightly increases TID hardness because a tiny bit more of the radiation (in particular beta) will be absorbed by the sensor before reaching the MOS gates which are most vulnerable. On the other hand, most commercial camera silicon is still fairly thin epitaxial, so this is likely negligible in a consumer camera. You will certainly be able to observe various patterns in a long, dark exposure, coming from various types of absorption (alpha/proton look like long straight "comet" tracks, a few electrons from a beta source generally look like curly tracks, and very occasional gamma "clumps" which deposit a large number of electrons in a small blob. There is an additional fictitious type of radiation used in the imaging sensor game which we call a "delta-ray", which is actually just when some radiation releases a secondary "knock-on" photo-electron from a silicon atom, this type of radiation isn't a separate type of radiation, can only be observed inside absorbing materials, and would be extremely rare from the types of radiation you're considering here). What is actually more concerning than sensor damage is probably the effect of both TID and displacement radiation on the camera sensor's filters, and in the case of a DSLR the mirror / prism coatings. I'm not an expert in that area. in brief: yes, your sensor will absolutely (eventually) get permanently damaged by (in CMOS, most likely) TID radiation. I would not suggest storing highly radioactive lenses "on-body" for long periods of time when you aren't shooting with them. Sorry for the long comment, hope it was of some interest.

I used to work in nuclear power for the US Navy, and I have to say this is an incredibly well done and informative video. For us US folks, 10 microseiverts is equal to 1 millirem. I just bought some very well taken care of SMC takumar lenses from a local, including the S-M-C 50 1.4 that you have that reads quite hotter than I would’ve ever thought. I’ll be storing this lens properly and not leave it in my camera when I’m done with it. Thanks again!

I'm an interventional radiology NHS nurse. On average we get (since you must consider the x-ray machine as if it was a very big camera) 2 to 5 FPS of x-rays for half an hour to 5-6 hours at a time, depending on the procedure. Obviously we are covered with lead and we have our radiation checkers which make sure you don't exceed the dosage you're allowed to take. I also own a beautiful mamiya-sekor 55mm 1.8, which I love, but I never found any sources to understand if it's radioactive or not, but since it's from the same generation and the same look of the 1.4. nevertheless I always keep it in its bag away from me and certainly not in my bedroom, even though it'll be a negligible dose compared to what I'm used to already

In astrophotography we take 'bias' frames and 'dark' frames. It is not uncommon to see the camera sensor recording cosmic rays. I'd be very interested to compare your lens results with what we see when shooting the stars. Should you have an interest get in contact and I'll give you some more info. In the meantime, this was really good work. You showed the effect of distance. This should fall off as an inverse square law. Your experiment with two lenses might simply be the sum of the first lens being close and the second lens being further, or there might be metal in the first lens that absorbs some of the radioactivity from the second lens. Anyway, overall it was very informative. Get in touch if you want to get a bit deeper into this.

Thank you for producing such a well researched video. I think it’s very important that people know of the risks so they can store these lenses safely. Nice job!

I was surprised that my old 1950s Kodak Bantam RF Camera showed a 4000 CPM count. Strong level for such a small rangefinder lens.

I am a research scientist (cancer research / molecular biology), and have worked with radioactivity. I can also confirm that this is a very well thought-out review. Thank you Simon for the wonderful thorough testing you did. I would like to add that my Super Takumar F1.4 has arrived last night! It is the late version, the least radioactive of them all, but it still made the list. I purchased it based on your reviews. Did a few test shots yesterday, and indeed, I love it!!! Beautiful pictures, so much more natural than my Canon EF-M lenses, which look really "digital" in comparison. Thank you for this wonderful recommendation! My copy has a very sticky focus ring, so I'll have to find out how to fix it.... another adventure awaits! ;

Great video. Appreciate your dedication to enlight the dangerous and safety measures in regards to radioactive lenses. Great thumps Up!

Hi Simon, Thank you for another excellent and informative video. A great follow-up to Part 1 and some much needed guidance for the growing vintage lens community. By your recommendation, my first vintage lens was the wonderful SMC Takumar 50mm f/1.4. So I had to laugh when it came out top of the list in terms of radioactivity. Wasn’t expecting that. I’m now thinking of storing this lens and others that I’m sure to purchase in a small metal safe. No doubt this is an overkill, but the fact that they are slightly radioactive is a good talking point and I also enjoy the warm tones.

Based on this evidence that you have presented very professionally, I had no fear in acquiring an SMC Takumar 1.4 recently. It is currently stored on the window sill of the spare bedroom, having a bit of UV treatment for the yellowed glass. The British weather though at the moment is not exactly UV friendly! I will store it very carefully on a shelf with caps on and at least three feet away from where we sit for any length of time. Caps will be on and use on the camera will be limited anyway, as I have so many other non radioactive lenses to use (vintage lens addict!).

Thank you for these videos. Clear and transparent knowledge goes a long way. :)

I enjoyed your treatment of radioactive lenses. It was not the usual inflammatory personal opinion piece I'm used to running across online, where the author is just trying to excite people without regard to the consequences of that excitement. The humility you show as a non expert demonstrates common sense. You will continue to pick up subscribers. I have enjoyed all of your videos and am rooting for your success. Also, your videos have come a long way from the first few! Your skills are sharpening nicely. Well done!!

Thanks for a very professionally though out, informative and produced video.

New lens measurements - right up against the counter, in a different position During the video, I asked for observations on my tests and measurements, and I would like to thank everyone who has commented (107 comments so far). Bo Zhang has alerted me to a feature of the Geiger Muller Counter I used. The counter's readings are extremely sensitive to precisely where the lens is placed right up against the counter. I kept the counter standing up-right, in the same position for all the tests. However, Bo Zhang has found ( and I've now found too) that the readings increase if one puts the lens up against the base, because that appears to be closest to the counter's measuring device. So here are the new measurements, excluding background radiation, putting the lenses right up against this new sweet spot at the base: SMC Takumar 50mm f1.4 - 18.148 μSv S-M-C Takumar 50mm f1.4 - 16.543 μSv Tomioka Auto Revuenon 55mm f1.2 - 16.061 μSv Carl Zeiss Jena Pancolar 50mm f1.8 - 12.896 μSv Mamiya/Sekor 55mm f1.4 - 11.765 μSv S-M-C Takumar 55mm f1.8 (earlier copy) - 10.329 μSv S-M-C Takumar 55mm f1.8 (later copy) - 10.140 μSv Yashica Yashinon DS 50mm f1.7 - 5.908 μSv Macro Takumar 50mm f4 (pre-set version) - 1.138 μSv Super Takumar 50mm f1.4 (8 elements, later version) - 0.403 μSv The counter is clearly very sensitive to changes in distance up close - even the difference between lenses with relatively "flat" rear elements, versus the more curved elements of other lenses.....or where the rear element sticks out at the back, versus being set behind a couple of mm's of a metal lip. I was surprised at how the measurements increased by between two and over four times by moving the lens around different parts of the counter. I now know that a much more expensive counter with a flat attachment for measurements, plus taking the glass out of the lens, would be the best way to get accurate very close up measurements. However, in terms of readings as one moves the lens away from the counter, the good news is that the sensitivity declines, and readings I reported in the video with the counter standing up-right are more in line with the counter on it's back, and become identical as you move more than a foot away from the counter.

Outstanding presentation. Quantifying the potential level of radiation individual lenses in various practical scenarios hedges out most speculation and serves as a clear guide for photographers. Thank you.

Excellent video, thanks for putting in the work.

Great video. I really appreciate seeing all this information

Big fan of your channel! great video and very helpful to know about the safety factor on these lenses!!

Literally the best camera channel on RU-vid.

I sold a dozen Takumar lenses. As much as I wanted to keep them, I just made the decision that I don’t want ANYTHING radioactive by my eyes. People tell me all the time that “I get more radiation from ....” , whatever. Why put anything radioactive by my face / eyes if I don’t need to? So I sold them.

Thank you for doing this, it’s an invaluable resource!

Very interesting video. Based on your video and others, I took the trouble of buying a GQ GMC-320 Plus to test my own Super Takumar lenses. I was happy to see that none of my slower Super Takumar M42 lenses were radioactive (28mm/F3.5, 35mm/F3.5, 55mm/F2, 135mm/F3.5, 150mm/F4) and neither was my Pentax 67 Super Takumar 200mm/F4 lens. When I tested, however, a recently bought Super Takumar M42 55/F1.8 lens (serial # 2159592), the meter went ballistic, registering over 800 CPM and over 5.3 uSv/h. It started flashing its little red warning light and sounding its alarm. The background levels in my home today are around 20 CPM and 0.12 uSv/h. I am somewhat over cautious and risk-averse, so my lovely, newly acquired lens is going to be stored in a concrete box in my shed till I figure out what to do with it.

Thanks for a great video! Indeed, the amount of radiation you get from these lenses is negligable, as you so nicely demonstrated. Word to the wise - don't eat your lens! Having worked with a lot of potentially dangerous radioactive compounds as a scientist, be assured (even beyond your experiments) that the radiation coming from the lens is no problem with proper storage. Didn't know radiation can damage the digital sensor, good to know. Your explanation was excellent, convincing and fun! Thanks!

a very good video just like all others from you. depending on research and testing yourself! I'm glad that you are out there and part your knowlage and experience with us. Very nice indeed! Stay healthy and take good care (:

Plastic blocks most alpha partials from these lenses. Plexiglass in fact. I just bought a Olympus OM-System G.Zuiko Auto-S 55mm f1.2 1974 Radioactive 3389 CPM lens. It is hot. More on the front lens than the back. Back is 950 CPM. The front is 3389 CPM. After reading this paper on the use of plastic to block the Alpha partials I stacked four 0.25 blocks of plexi on the front of the lens. Using the same brand of GQ GMC 320 Plus. I was able to measure a drop from 3389 CPM to 540 CPM. Now that is news. Jim

Amazing scientific investigation on the topic! Great job! Thanks

just a note - keeping lenses in the basements or even in living areas with caps on and in containers is the ideal environment for fungal growth..

I came for lenses, and ended up learning about radiation. Extremely informative Sir & Thank you for taking the time to make it 👍

Excellent well researched video Simon. Thanks for adding some objective information to this emotion charged topic!

To store my Super Takumar lenses, I just had the idea of using watch cases. Fossil watches come in perfectly-sized steel / tin boxes, with a foam liner. This is my perfect storage solution. Hope this helps.

Fascinating video! Thank you

Great presentation! Thanks 😊

Good job very well executed. While no longer active, no pun intended, I used to be a specialist in nuclear, biological, and chemical warfare in the armed forces (not the UK) and I find your research accurate and well presented. I have handled far more radioactive material in I certainly wouldn't see radioactive lenses as we are talking about such low levels of radiation as a danger; as you have pointed out (correctly I may add) at those distances you store the lenses the background radiation is the main source of exposure of radiation. The only thing I could point out that at conclusion number 3; the lens isn't more radioactive or dangerous after being chipped unless there is the risk of more material being dislodged from the glass (substantial damage, several cracks visible in and around the impact zone), the radioactive material is part of the glass itself, but now there is a risk of small alpha-emitting glass dust in the air when the impact happened and my recommendation, if you are afraid of the long term effects of radiation-related issues: - Hold your breath. - Evacuate the room, depending on the ventilation, the entire house/flat. - Ventilate the room/house/flat while wearing a high-quality face mask (not surgical masks like popular now during the pandemics) that protects from inhalation when reentering the premises. - Use a safe method of hoovering/vacuuming the area (central vacuum if you have it that expels the sucked up air outside or with a HEPA filter) or simply wet wipe it up to make sure you don't get the particles up in the air. This is if you are worried and ultra-careful, or call me to sanitize. ;)

If your looking for a lead storage solution you could get some of the old film storage bags that they sell to protect film from airport x-rays. There are still some available and I know B&H sells them.

Thank you very much for the well detailed video!

I usually use a focal reducer (FR) on my M4/3 body and have even less concern when using Super Tak 50/1.4 (other other Thoriated glass) when it comes to long term impact on a sensor. For M42 to M4/3, I find the FR is a must for the camera bag. IMO, there are decent FR's at or under $100 (e.g. Viltrox)...maybe not to the level of Metabones...but of good quality and performance for my needs. That extra set of glass in between the sensor and Thoriated rear element of the lens is an adequate barrier to low energy gamma and shielding overkill for the beta and alpha. (note: high energy gamma can be shielded using certain materials...the 2-4-24 rule being a good measurement of effecting shielding. 2 inches of lead = 4 inches of steel = 24 inches of water; e.g., I have stood over a university research/critical reactor core to observe the blue light of the Cherenkov radiation; I had an 18 foot water column between myself and the core.) In my youth I was a Chemistry and Radiological Controls officer (CRA) on a US nuclear submarine, so my knowledge of the issue is on a professional level. In this context, I have no issue using these lenses for their intended purposes (i.e., I do not place them in contact with the cornea of my eyeball...nor do I grind them into dust). Very early in the development of Thoriated glass, various regulations (incl. self regulation by manufacturers) exempted the use of thoriated glass for eyepieces in microscopes, binoculars, view finders, etc. The reason being that these lens elements would be too close to the cornea, where a thin living cell layer could be exposed to alphas. IMO. PS: Thorium-232 is the only naturally occurring isotope on Earth, with a half-life of over 14.1 Billion years (very low radioactivity). It is as common in the Earth's crust as Pb (lead). About 2cc's per cubic meter of Earth. The reason China is effectively the single source for many rare earth elements is due to Western regulations, whereby Thorium, once dug from the ground and separated from the valuable Lanthanides, must be treated separately as low level rad-waste. The US has massive sources of rare earths...but their mining is cost prohibitive due to these regs.

Great video. Tnx for detail examples

Greetings from Essex County (UK)! Thank you for an entertaining and informative video. I own a 50mm f1.4 Super-Takumar lens (SN: 4111346) which I use with my Canon 80D. I took it to work (thin blue line) and my CBRN colleagues used their equipment to check if my GQ GMC-500+ is working. The background level was correct, but my highest home reading (just over 3000 cpm // 19 uSv/h) was twice their pro kit reading. Their £10000 geiger was showing a maximum level of about 10 uSv/h. Now, I'll keep using my amateur geiger counter, but take the highest readings with a pinch of salt. I'm stil storing my Takumar in its own Peli case lined with 6mm thick lead plates. And not under my pillow. 😂

Oh no! This explaines the reason i have lost my hair,i believe. I love my takumar 50 f 1.4 that i always sleep with it under my pillow.im afraid of theift,a bad neighborhood here.after 15 yrs,im now bald.if i remove lens from sleeping area,will my hair grow back?

Thank you for performing these tests! Testing the rear element cover was a good idea. However, PLEASE do not purchase lead to shield against these lenses. These lenses emit such tiny amounts of radiation, storing them in any closet is perfectly fine. If you absolutely feel the need to shield these lenses, steel has a very high attenuation of gamma radiation as well. Bringing any amount of VERY hazardous lead into your home is much more dangerous than then these lenses!

Several lens manufacturers in the 1960s were looking for ways to create new types of glass with a high refractive index and a low chromatic aberration. They started to use rare earth compounds, such as fluorite and quartz, even radioactive thorium dioxide (ThO2). Quartz and fluorite are quite expensive and hard to produce. For other lenses they added small amounts of thorium dioxide to the glass, but only in the rear or front lens group. The radioactivity (alpha radiation) of the thorium dioxide may cause self-degradation of the glass (turning it brownish yellow over time). Not all lenses turn yellow, however. Alpha radiation is effectively shielded by a few centimeters of air, paper or the thin layer of dead skin cells that make up the epidermis, so it is not particularly dangerous. The rear cap of the lens will block most of the radiation effectively and there is no danger of fogging the film or damaging the sensor in a digital camera. Radiation levels are stated in microsievert per hour (μSv/h). A set of dental radiographs will expose you to approx. 5 μSv of X-rays. If a lens was to emit 5 μSv/h, it would generate the same dose of alpha radiation in 1 hour.

Very informative, thank you.

Basement or Garage? Great possible way to encourage fungus on your lenses. A dedicated dry area away from most human activity like a dedicated closet or room would be the most effective. If you have a dry temperature regulated basement, that might be fine too. Excellent videos on the subject. Well researched. :)

One danger we should take into account about “not breaking radioactive lenses" is the possible reactions of the lens owners...

Storing radioactive lenses between one or more Acrylic Plexiglass sheets of 1/2 inch reduces the CPM a lot, almost to zero.

Simon thanks so much for these videos my family and I have been having similar discussions, the lens I am concerned about is my Zeiss Jena Tessar 50 2,8 I just ordered a Geiger counter to check. Will let you know what I see your list of radioactive lenses is helpful it would be interesting to see which lenses you tested that are NOt radioactive. I have a few helios 44's and Meyer Otik Orenston that I am curious about as well.

I bought a brand new Super Takumar 50mm 1.4.... It came in the mail, and I immediately put it up to my eye, and was looking through the lens for about 30-45 seconds. I didn't think it was radioactive because it was the 8 element. Turns out, it was radioactive, I got super paranoid, and went to the eye doc. He seemed to brush off my concerns after giving me an eye exam, but I swear I had a case of dry eye in that particular eye for at least 2 weeks.

Great video, thank you !!

Thankyou for your hard work on all your videos and after watching your videos I bought 4 vintage lenses and one lens was radioactive the yashinon 55mm. I also had to buy a Geiger meter after watching part 1 of your video on radio active lenses!!!😮 I keep my lens in a plastic container and the reading from the meter next to the box was nothing more than background radiation

(Not to mention neutron emission). Some houses are built on soil that has naturally radioactive sand. We live with a nuclear reactor everyday, it rises in the morning and sets in the evening. Was it Rolf Sievert who remarked that there is no safe level of radiation. The safe level drops periodically as the ability to detect tissue damage improves. No two bodies react in the same way. Some people develop tumours whilst others don't. That's life I guess.

Thank you Simon 🙏

Respect you for an excellent video

Great explanation of the units and the effects of distance. I bought a dosimeter for testing my old lenses but was totally ignorant concerning the readings obtained. It was difficult to find the info explained in a clear way or at least in layman's terms. The burning question here though is cumulative radiation. As far as I understand radiation is cumulative so it will build up albeit slowly until a person passes away. There must be some added risk because it's adding to the dose a person might be expected to have during the course of their life.

Very well researched and presented! While I do not intend to minimize the damage of ionizing radiation, keep in mind that cataracts are not necessarily caused by radiation. Our cell tissues don't regenerate as well after decades of use. Cataracts and other harm may be caused in part by natural background radiation (like the sunlight we love) over a long lifetime. Exposures can be cumulative, but the natural background may be the biggest component when considering the added risk of using these lenses.

Oh forgot to say: thanks Simon

Excellent video.

Seemes like this may be an opportunity for a company to produce m42 rear lens caps containing a small amount of lead shielding. Actually I'm wondering if I should DIY some sheet lead from old lead film bags. I really like my old takumars. I honestly don't use them that often. Thanks for the information.

Good video. I only own one radioactive lens (Yashica Yashinon 50mm f/2). I keep it in storage away from the other lenses. In 2019 I encountered an SMC Takumar 50mm f/1.4 with a shattered back element, at a camera fair. The people behind the table had no idea. They had even tried to mount it on their camera. Thorium Dioxide dust in the house is not a good idea. I measured a very high count of 40.000 µSv/h from that lens (compared to your approx. 8 thousand. Background was high in that lens/camera fair (about 1 µSv/h). Geiger counter is a callibrated Inspector+ with a pancake tube at the back.

I’m new to your channel. I have the same Geiger counter you used, I’ve had for about 2-3 years. My SMC Takumar 50mm f1.4 measurement is about 40% of your measurement, maybe because it’s further from calibration or maybe indicating the accuracy of the instrument. Background radiation measurement hasn’t changed over the years. My S-M-C Takumar 35mm f2 radiation level is comparable to the 50mm f1.4. My SMC Takumar 55mm f1.8 is about 40% of the 50mm. I have 14 Takumar lenses, mostly S-M-C, and the rest measure close to background levels. The only storage precautions I take is to use metal lens caps, rear and front, on the offending lenses.9

Great great video. Thanks!

I store my SMC Takumar 50 1.4 in my dry cabinet in the apartment, in the office room, with all my other cameras, lenses, and stuff... I just keep it with both caps on and never store it mounted on my camera. No more protection. I feel absolutely safe. Like you just show with your great video, the radioactivity is so small there is no real danger. But maybe I should keep it to my eyes for few hours every day to cure my myopia? 🤔😁

Well done! The Inverse Square Law is your friend!

Interesting video! Shooting in liveview mode and holding the camera away from your eyes is probably an additional step one could take to minimize the risk. Doesn't work with film though.

There would be more danger from contact with the lead lining than from any radioactivity out of the lenses. Very informative videos tho, thank you!

I don't have thorium-dioxide based radioactive lenses, but I also would recommend not to have such lens attached to a film camera with film inside over a longer period of time. The radiation can harm the film emulsion and potentially expose it.

in your camera collection would you happen to have a Konica s2 auto? Many of Konicas hexanon lenses are radioactive, and I am a little worried....

Well researched, well presented, and reasonably considered. Great video on the subject, far and above the ghost stories told elsewhere I've never been all that worried and simply (as the tongue in cheek bit goes) don't bite or sleep with the lenses underneath my pillow. I believe I have a total of 5 thorium impregnated pieces, the highest is likely the early Hexanon 57/1.2, and due to size I'd imagine, my early 67 Takumar 105/2.4. I pay it little mind. Some of the very best vintage lenses used thorium in this way and I don't believe this is coincidental. And also, if I'm honest and considering the relative safety in the end, there's just something a little bit awesome about owning and using photographic lenses that have a half-life. :)

Out of curiosity, have you tested the resistance an old m42 film camera provides similar to the test with the digital camera bodies?

Sampled a Super Takumar 50mm 1.8 with a Radeye PRD. Background was 12 micro Sv. From the front the level hardly deviated even close to the lens. From the rear it reached 40+ micro Sv with units detector against the rear element. But a metre away it was back to background.

Really nice video. Really interesting. That's mainly because I am an happy owner of a Super Takumar 50mm f1.4. According to your list, the Super Takumar is not that radioactive, emitting the lowest amount of mSv. My question for you regards the little note about this lens: you say you tested the #2 late version. Do we have to expect that the early version could be more radioactive? And how to recognize the actual version of the lens? Thank you very much. Greetings from Italy.

I’m trying to decide if I should buy a Geiger counter. I do own quite a few, and I store them in an aluminum case when not in use, but they are grouped in close proximity to one another. Your video was excellent putting the issue into perspective. I actually don’t see an issue using them on a camera. I think I spend only 10% of using a camera with it actually held by my eye.. if that. I need to look at that list carefully - were there surprises? Some that were radioactive that you hadn’t realized? Knowledge is the best way to approach a personal solution.

Thanks you from France !

Does the radioactive lenses affect the sensor? By the way I love your video on the Takumar lenses, as I have several of them that I have picked up at thrift stores. Such little gems when I find them.

I don’t know if you’ll see this but I have a Super-Takumar 50/1.4 lens that puts out 4000cpm of beta/gamma and 28,000cpm of alpha/beta/gamma. This was measured at United Nuclear, a supplier of radioactive materials and various equipment and I have a certificate from them of the radioactivity

Thanks for sharing

Great Video - Thanks for answering so many questions. The only question left is does any radiation reflect up through a DSLR pentaprism? I only use lenses like my CZJ Pancolor on mirrorless but it does puzzle me...

I measured about 200 lenses a long time ago already and only a few of them showed levels that could classify them as "radioactive". For example, it is evident from your readings that the Super-Takumar 50mm f/1.4 (8/7) is another confirmation that the lens was not built with glass contaning thorium, but with glass containing improperly purified lanthanum. As per their statement, Asahi Optical Co. started to use glass containg thorium only with their Super-Multi-Coated series and stopped its use in the late 70s.

Hi, nice video and info. I wish you've tested the lens against a film camera also. And, do you know if the radioactive lens affects the film if it's forgotten inside for a long period?

Thoriated glass is typically used within the REAR elements, NOT the front element. It is the improved refractive properties of the Thorium-232 doped glass that made it a choice material for certain premium lenses in the 1960's-1970's.

Thank you...

fascinating!

thank you

Time Distance Shielding Measurements and dosimetry Combine or accentuate. For time, less is more, for the others; more is more, and more is better. And keeping tracking exposure is equally important

One sunny morning 10 years ago i bought a Mamiya sekor 60mm 2.8, from day 1 a was aware of the radiation but fell in love with it. Its my daily shooter, going with me everywhere and always on my camera. I even bought a second copy just in case :) Good to know that they should be kept apart, and i might not store my super-multi-coated takumar in my bedroom anymore. I also use aluminium lenscaps, lining them with lead might be a good idea since radiation is emmited most at the front and rear of the lens.

I recently got rid of my in pristine condition Super Takumar f1.4 50mm. My reason for this is just understanding that if anything else in my house was emitting radioactivity I wouldn't make excuses to keep it. Or find out a safe way to store my lens. It comes down to the fact that I am a gear geek and love vintage lenses but I shouldn't make excuses to keep a radioactive object just because its a lens. Its obvious to me if it was anything else I'd remove it immediately and not store it in a led box or tinfoil.. good thing not all lenses are made with thorium.

I come across this experimenting with lenses as you did, I fond an old super Takumar lens. I like the pictures it took and the way I was able to manipulate the photo. I made a mistake and left the lens on my digital camera, I went to use it a couple of months later and noticed there was a malfunction with the cameras metering and speed. I took it o be checked out. the camera repair told me that sometimes the radio active lenses will mess up the electronics of the digital camera. They could repair it or I could buy another due to cost. I'm not saying this will happen to others, I happened to me

great vid!! really nice also i would like to ask you if u know something about the auto mamiya sekor 50mm f2 I wonder if this lens is radioactive, because the big brothers mamiya sekor 55mm f1.4 and 1.8 are radioactive it seems made by tomioka but idk about the this one if u have any information i will really apreciated so much!!! besides do you know another 55mm lens with out thorium elements? i dont want to take the risk with the takumars i know they have an excellent performance and great quality but risky in my humble opinion. thank so much for your passion and dedication im still learning about the world of vintage lenses is really fun take care.

" In conclusion - no, you can’t get sick or die from radioactive lenses. You’d have to spend months in a room filled with 2 million of them in order to feel any consequences, and I believe no one’s collection is that big. So, if you have a couple of good ones, don’t be afraid to use them. " Quote from some article.

Thank you very much for this informative video. I have a Super Takumar 55mm f1.8 . SN begins with 16... . It has a light yellow tint on front and back glass. Do you know is it a radioactive one or not?

Thank you for doing this testing! Personally, I am going to reduce how often I smuggle these lenses in my shorts to only four or five times a year.

Very interesting. I thought Leica also had a line of thorium lenses. I've been interested because of the aesthetic I've heard about thorium lenses. Just a couple ideas. Radiation follows the inverse square law. Radiation drops proportionally by the square of the distance from the source. That would give you a predictable measure with your counter. I'm guessing your counter is better counting Alpha particles than beta particles or gamma rays per se. So the drop off may be even greater over a given distance Without going into detail beta particles can be either an electron or a positron (sometimes thought of as an anti-electron). Both Alpha an beta are particles which means they can be stopped or retarded by a physical barrier. One more thing, as you probably already know, you can buy lead foil on line (depending local laws) and use it to line a hard lens case or box, you can also buy gold even platinum dental foil (not gold artisanal foil) if you want something more aesthetic and will not pollute the environment as lead is want to do. There is probably no reason you couldn't use thin copper or brass sheets given how little radiation is given off by these lenses.

Hi Simon. Could you please tell me what are the first 2 digits from your SMC Tak 55 1.8 that is not radioactive ? I would like to buy one and maybe this info will help me. I saw on RU-vid tests on SMC Tak 55 1.8 with serials 6.3 and 7.0 mil and it turns out to be quite radioactive. Thanks !

I have a very similar unit. Be sure you take the lens off the camera to protect the CCDs. Don't use the view finder. Use the LCD. I am going in for my first Cataract surgery next week. My radioactive lenses so far: Olympus OM-System G.Zuiko Auto-S 55mm f1.2 1974 Radioactive 3389 CPM Auto Mamiya Sekor 55mm F1.4 with M42 Mount TOMIOKA Design Radioactive 360 CPM Asahi Super Takumar 50mm f1.4 Radioactive 2250 CPM Asahi Super-Multi-Coated Takumar 35mm f2 Radioactive 1850 CPM Asahi Super-Multi-Coated Takumar 55mm f1.8 Radioactive 750 CPM

Hi Simon - I see from your list that the early version of the Super Takumar 8 element lens are not radioactive but the later versions are. Do you know how to tell which versions are which? Many thanks.

Spare a thought for me! With exactly the same Geiger counter, I have a Super Takumar 50mm f1.4 that's giving me a reading of 1800 CPM when the rear glass is pressed right up to the vents on the underside of the counter. Thankfully when it's a 50cm away it reverts back to background levels. And on the camera, the Geiger counter registers 120 CPM, so not bad.

One solution would be to buy lead sheet foil 1/16” and use an old hard lens case. Cut 2 circles and 1 strip. So as to place in the bottom and lid and inside. Then replace the foam rubber lining. The radiation count will now be minimal. Leas sheets 12”x12”x1/16” available on Amazon.

So is the carl zeiss jena zebra lenses tessar 50mm 2.8 not safe? What about the Helios 44?

Had another thought 💭.. obviously the radiation continues to be thrown even if you are 3 feet or more away, however levels measured fade to that of background radiation. My thought is radiation, like photons spread randomly about as they are thrown and are not “directed” in any direction - IE out the rear of the lens. I hadn’t really thought about this before, but it has provided a little food for thought concerning how radioactive particles behave.