Radioactive Lenses - Super Takumar 50mm f1.4 - and other Radioactive Household Items.
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- เผยแพร่เมื่อ 7 ก.ค. 2024
- Having done a recent video where I repaired and tested a radioactive Super Takumar 50mm f1.4 camera lens, I thought it would be interesting to see how radioactive these old lenses actually are, in relation to other household items.
In the video I'll do my best to explain why these lenses are radioactive and then test the lens under various conditions. As a comparison I'll also test a banana, a smoke detector, an old luminous watch and a lamp mantle.
You can see the previous video featuring this lens here:
• Radioactive Lens - Sup...
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The best radioactive lenses related material I have seen so far on TH-cam. I really like your idea of long exposure radioactive lens test. Thank you.
Thanks Sang Do, I wanted to make the video as accurate as possible - the long exposure test worked really well.
I'd love to do a test over a period of one year, leaving the lens on a camera all the time, to see if the radiation does any noticeable damage to the sensor - but I don't particularly want to potentially sacrifice a camera for this purpose so I think I'll leave that test for someone else.
He is genious! 👍
Absolutely fascinating video! Thanks for taking the time to create it
Thanks Tobias, glad you enjoyed it :-)
Man, what a fantastic video. This must have taken you some time to make. Great all around.
Hi Michael, all of my videos seem to take far too long to make and this one definitely topped all the others for "amount of effort per minute of video" - I was probably working on this video for two or three weeks (not every minute of every day). It doesn't help that I seem to have a complete inability to speak in a coherent manor when the camera or audio recorder is rolling - SO many outtakes!!!!
Cheers for the comment.
Thank you so much for the detailed explanations!!
Cheers Matija, it's a really interesting subject and my video only touches the surface, but hopefully it'll give people a basic understanding. Thanks for the comment.
Great explanation
Cheers Joel, I tried my best to explain everything without getting too technical - it's a fascinating subject.
Fascinating. Thank you.
Cheers rdcoff, glad you liked it.
Very helpful video! Thanks a lot for your efforts.
Cheers Andre, glad the video was useful - I tried my best to make it relatively accurate and not over dramatic.
Very thorough. Thank you.
Thanks Pete Mc, glad you liked it.
Wonderful!
Cheers Ramon, glad you liked it :-)
Firstly , this is one of the most expansive videos with clear information on the use and dangers of Radioactive hot lenses. The comparison with the various other objects definitely helped.
That said I've had one death in my family and close circles in the last five years and another cancer case. The first one was my uncle who was a photographer and used various lenses from the 60's all the way upto the 90's.
Secondly I have another family friend and store owner who ran a photography store from whom I bought a lot of glass. he had an antire stock if old lenses in his shop lying right behind his head. This was for close to 39 years and he worked at this shop for so long. He has been diagnosed with Leukaemia and is undergoing treatment. Im planning to tell him about this so the doctors can try and see if there are specialized treatments since there is a chance that this could have been the root cause. Keeping my fingers crossed and i will find my old lenses which are hot and place them in lead containers to avoid further damage.
Hi What's on My Table, I thought the comparison to other household items made sense because to most people, saying a thing gives out "this" amount of radiation is kind of meaningless unless you have something you're more familiar with to compare it to - so I'm glad you found that bit useful.
I think you'll find people who will argue all day long as to whether these lenses are dangerous or not - my take on it is that they're not supremely unsafe, however it seems only logical to keep them at a distance when not actually using them (from my testing, a few feet away is all you need, to see no increase in radiation above ambient levels). Some people will argue, probably correctly, that there are areas of the world where background radiation is far higher than others, and taking a flight in an aeroplane will expose you to far more radiation than on the ground, yet people are allowed to live in and visit those more radioactive areas and airline pilots and cabin crew don't suddenly grow two heads. From what I've found out, and I'm ignoring high radiation doses such someone might receive during some sort of disaster situation, the more radiation you're exposed to during your life, the more the risk increases, even if only by a small amount, hence I don't recommend sleeping with a bag full of hot lenses as your pillow.
There's still a surprisingly large amount of radiation from these lenses (and other objects such as luminous switches) that will penetrate a thin walled lead lined box - I made myself a box that consists of about 2.5mm of aluminium, then 12mm of wood, followed by two layers of lead flashing and then 6mm of wood on the outside - it reduces the radiation a bit, but not as much as I expected, although, as before, once you're over a foot away, I couldn't detect anything more than background radiation. So if you make a box, I'd still keep it in a corner of the room. One of the key reasons I made the video in the first place was because I was constantly hearing people say "these lenses only produce alpha radiation which can't penetrate your skin so they're perfectly safe", which just isn't the case - they may well be right that they're perfectly safe, but not for the reasons they have given.
Sorry, I've kind of waffled on for ages there, but I hope some of the info might be vaguely interesting.
Note to self, do eat bananas, don't eat ground thoriated glass. :) Good video Tim.
Cheers Benedict, bananas = good, thoriated glass and old lamp mantles = bad!!!!
I wanted to get hold of a Fiestaware Red plate or something else in the range because the older ones of those were similarly radioactive but I couldn't find any when I looked. I even went through the bag of marbles that I has as a kid because some marbles contained Uranium - sadly none of mine did, not even the one I swallowed when I was a kid - that would have been a cool story for the video!!!!!!
Actually, maybe i should have that printed on a T-Shirt "Note to self, do eat bananas, don't eat ground thoriated glass"!!!!
@@GrumpyTim Interesting idea....
Really like the video and the outro! I took my early 7 element version to my HS lab and confirmed it was radio active with an analog counter, which certainly could use some calibration. The result I found was 20x background radiation at the rear element, and didn't consider it a significant risk. Your experiment on long exposure was a really cool idea and I plan to do the same with my NEX-7 to verify the result. Certainly not looking into the rear element of that lens from now on!
Hi Richard, cheers for watching and commenting - I'd agree with your thinking of "not considering it a significant risk", and I'd guess that the occasional glance into the rear element at close proximity wouldn't in actual fact be that bad, BUT for my own peace of mind I won't be doing that. Same thing applies to leaving the lens attached to a digital camera for long periods of time - it may well need many years before there's any lasting damage to the sensor (if in fact there is ever any damage to the sensor), but it's so easy to simply take the lens off the camera between usage, then that's what I do.
These old radioactive lenses are a really interesting topic and an awesome bit of photographic history to own, not to mention that they're actually a really good lens!!!
That was fun!
Cheers Chad, glad you enjoyed it 😀
VERY informative video. Thank you!!!... 👍🏻
Cheers Flat Twin Frog, glad you liked it :-)
Great video. Thank for sharing!
Cheers One Eye - I liked your radioactive lens video that you just released.
@@GrumpyTim Thank you :)
Very interesting
Hi Derek, the old radioactive lenses are quite fascinating, in fact radioactivity itself is pretty amazing, and far more complex than a lot of popular knowledge will have you believe.
This video is amazing. Liked and subscribed!
Thanks so much Michael, that's ace.
Great video! I just recieved a radioactive Takumar SMC 1.8 55mm lens and I absolutly love it.
One note, please dont keep radium exposed because it is a very nasty element. At least keep it in a sealed bag to stop radium dust from falling off.
Cheers allRadioactive, it's so long since I made this video I was thinking "radium, what radium?" but of course, the watch dial!!!!! I have a box of old watch mechanisms, a few of which have the radium paint - each watch is in it's own envelope, the whole lot are in a sealed plastic bag and that bag is in a box, on a shelf, in a room where no one goes, so they're well enough contained for now. I'd love to go back in time and see one of the radium dials when it was new because they supposedly had a really good glow - now, more or less all of that luminosity has gone and you're left with a pretty useless, dull looking, radioactive watch face.
I'm a musician and radioactive. Good informative video! Explained very well. Good teacher!
Thanks David, glad you enjoyed the video and thanks for leaving a comment, much appreciated.
I am a musician too. I also designed and produce a Pro Audio vacuum tube mic preamp. I started collecting lenses, some 38 lenses ago, to make TH-cam videos that explain and demo the preamp in 4K. I also upgraded my computer to handle those files sizes.
Thank you for what actually feels like a proper video. I was looking into these lenses about 2-3 years ago and I couldn't find a clear answer. I got someone saying it's just Alpha and Beta, then I got a different person saying it was Gama which I know is dangerous.
Hi Mitch, there probably is a small amount of Gamma emitted from these lenses, but probably not enough to get extremely excited about. I've read more material since I made this video which says that, although the main decay chain emits alpha and beta, some of the daughter isotopes have progeny that can/do emit gamma. However, I haven't checked the accuracy of this information but I presume it's accurate.
There is another way these lenses could emit Gamma radiation, although this is only a theory and again I have no solid proof that this could happen in the case of these lenses, but there is a phenomenon known as Bremsstrahlung or Braking Radiation, where a beta particle hits an atom of lead with such force that it causes the lead to decay, emitting gamma radiation. At the end of the Thorium decay chain is lead, and although the half life of Thorium is 14 or so billion years (meaning that after 14 or so billion years, half of the original Thorium will have decayed), the point in time that any atom decays is totally unpredictable, so it's not unreasonable to assume that some atoms have already made the journey to their stable form of lead, therefore, there could be some lead atoms close enough for a beta particle to smash into them causing them to decay, emitting gamma radiation. As I said earlier, this is only my own theory and I might be distorting physics beyond any reasonable logic, so don't take this as fact.
This additional information doesn't change my recommendations - these lenses don't really emit that much radiation compared to the background radiation that we're all exposed to, all day, every day - background radiation can be significantly higher in some locations due to the minerals in the ground etc. Also, flying in a plane, high in the atmosphere subjects your entire body to a far higher level of radiation than on the ground but we still do that (and pilots do it as their job). I personally see no reason not to use these lenses but a little caution and common sense doesn't go a miss - don't spend all your time unnecessarily close to the lens (in the case of my Takumar it's the rear element that's radioactive, so don't sleep with the rear element balanced on your forehead every night). Probably most importantly is not to ingest fragments of the glass should it get smashed and ground into a dusty powder - inside the body this level of radiation would be less than ideal.
On the subject of Gamma being more dangerous than Alpha and Beta, yes, it can travel further and penetrate the body more, but if there were significant levels travelling further than, say a foot from the lens, then they would be measurable when the lens is moved away from the geiger counter. Also, although people say things like "Alpha is safe because it won't penetrate the skin", if you swallow an alpha emitter, it'll be right next to your internal organs, and at that proximity it can be dangerous.
Hope that sort of helps.
Extremely informative video and thanks for following up with additional commebts like this. 👍
Hello again, what is happening is that the two naturally occurring isotopes of thorium decay at different rates, leading to the ‘growing in’ of two different isotopes of radium, which emit gamma rays. The main problem is the (tiny) minority isotope Thorium-230, which leads to in growth of radium-226 which emits 186keV gamma radiation, as well as alpha particles, and has a half life of 1600 years. If we make the reasonable assumption that all the thorium decay products are volatilised in the glass melt, then the newly made lens has negligible radioactivity. From that point, thorium decay product isotopes with shorter half lives (ie more radioactive disintegrations per second) start to appear and continue to build up until a radioactive ‘equilibrium’ condition is reached, after perhaps a few hundred years (I haven’t calculated it yet)... A Super Takumar 50mm f1.4 lens would have had about zero Becquerels(Bq, SI unit of radioactive decay = 1 disintegration per second) of radium-226 when new, but my example made c. 1967 now has about 40000Bq of radium-226 and this will roughly double over the next 50 years. I have two examples of the f1.8 version and the radium-226 content is roughly half, (i.e. about 20000Bq) which is what one might expect as the lens element has roughly half the area of the f1.4 version (almost 1 f stop). For a given example of the lens, the radioactivity is only a function of the time since manufacture. Concerning the coating, it’s quite possible that thorium elements were coated with thorium compounds in order to achieve suitable refractive indices. The coatings are quite hard and can only be removed by quite aggressive cleaning processes. However, avoid chipping the glass because if one were to cut oneself on a glass splinter, that could give rise to a significant internal radiation dose. On the Takumar lenses, the thorium element(s) are usually in the internal group between the iris diaphragm and the rear element and hence not accessible without dismantling the lens. A scratch on the rear lens element presents no radioactive risk.
Hi Jon, sorry, I hadn't seen your comment before - TH-cam tends not to inform me about third party comments in an existing comment thread, so I only see them if I go searching for them. Thanks for the additional information, I'll add that to my library.
Nice video!
Cheers Craig, much appreciated.
oh my god people don't panic takumar lenses won't kill you, people used it for over 50 years and no one got cancer from them, as long as you don't eat it you should be fine and so does your camera..... literally these radioactive lenses are that good and that sharp that I would never ever switch to other ones
Great video. You probably know that the Super-Multi-Coated Takumar 55mm f1.8 lenses have thorium glass as does the 35mm f2 Super Takumar. Also some Medium format Takumars are same. Thank you. Mike.
Cheers Mike, I'd read that there were a fair few Takumar lenses containing Thorium, along with a fair few other manufacturers at that time. At present I only have this Takumar and a 55mm Mamiya Sekor f1.8 that are radioactive, but I always check any suspicious new arrivals, purely out of scientific curiosity.
NICE VIDEO
Cheers Carmine, glad you liked it.
VERY GOOD. This hits the nail on the head.
Cheers jmoss99, I tried my best to make the video simple, yet still informative enough to give a basic understanding about these old radioactive lenses.
You bet. I am an EE, Programmer, Musician and Filmmaker, but having the following list of lenses I was trying to know how to deal with the risk issues of radioactive lenses. This is a scientific approach which I value.
Asahi Super-Multi-Coated Takumar 55mm f1.8
Asahi Super-Multi-Coated Takumar 35mm f2
Asahi Super-Multi-Coated Takumar 28mm f3.5
Asahi Super Takumar 50mm f1.4 Radioactive rear element baked into glass
Takumar Super multi coated 135mm f3.5
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FUJINON EBC SW 28mm f3.5
FUJINON 55mm f1.8
FUJINON 55mm f2.2
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Russian Jupiter 9 85mm f2 (1976 version)
Russian Helios 44-2 58mm f2
Russian HELIOS 81H 81N 2/50
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That's a nice collection of lenses there - I'm guessing that you're familiar with the list of radioactive lenses on this camerapedia page camerapedia.fandom.com/wiki/Radioactive_lenses - I don't know how accurate or complete the list is, but it's a useful enough source of information to help identify some of the radioactive lenses.
I'm happy enough with my radioactive lens to just keep it in a corner of a room where I don't spend much time - from my own tests, being anything more than a foot away reduces the radiation dose you receive to little (if any) more than background radiation but I always like to err on the cautious side. I'm quite happy to use my lens because the actual increase in my lifetime dose or radiation will be absolutely tiny, but as I said in the video I wouldn't sleep with it in the bed.
I do know about that site. It doesn't seem to complete. I wonder when it was last updated? I don't think it is good to leave the lens on the camera. I think it could hurt the sensor. I should look into a affordable geiger counter for this. There seems to be some under $100 on Amazon. That might be good enough for this. I will need to research it though. What do you suggest?
I keep the lenses in lens cases and the cases in a plastic clear case, and the case down in my lab. I am in that room a lot.
Yeah, I designed a Pro Audio vacuum tube mic preamp/limiter and needed to produce some interesting images of it in use. I found the vintage prime lenses to perform much better than the new lenses. So, I started collecting some. The Russian lenses have not made it to me yet. It takes a long time to get shipments out of Russia, but the make in time.
Thanks for your good work.
Jim Moss
Hi Jim
I agree, the radioactive lens list looks like it probably hasn't been updated for a while but it's still a nice starting point - and someone bothered to make it in the first place, so thanks to them for their work.
Assuming you basically want to check if a lens is radioactive or not and maybe be able to tell how radioactive it is in relation to another lens that you own, a cheap Geiger counter like the GQ Electronics GMC-300E that I have should do the trick - mine was unsurprisingly, bough from Amazon. If you wanted to do really scientific analysis of the lenses, you'd probably want something much better but I wouldn't know what to advise for that. If you're wanting to measure Alpha radiation with any sort of accuracy, you'd want a Geiger counter with an open ended chamber, usually protected by a mica window. I've been recommended "Geiger Fever" but I haven't checked him out yet - I think he does reviews of Geiger Counters, so he might be worth a look.
The fact that you're in your lab a lot, and that's where you keep your lenses shouldn't be a problem - maybe if the case they were in was doubling up as your chair, you'd get an increased dose of radiation over background levels but depending on who you ask, even that wouldn't be particularly dangerous. If you do get a Geiger Counter, you can do a simple test, move the case of lenses out of the room and run the Geiger counter for half an hour and see what your average radiation level is, then repeat this after moving the lenses back into the room - unless your Geiger counter is within a foot or so of the lenses, then I wouldn't expect to see an increase (well no more than normal variation in background radiation - it can fluctuate a fair bit - it might even double from your initial reading but twice not a lot is still not a lot.
I like the sound of your vacuum tube mic preamp, that's cool. I love the look that I get using vintage lenses, particularly for video - it looks somehow less clinical. I've tended to shoot fully manual for years so not having auto focus and stuff isn't really something I miss. Maybe if I was a sports photographer or similar I'd think differently.
Great video! I just watched a Mark Holtze video about the 8 element and the newer 7 element non-radioactive version. I think to prevent third eye growth I'll either look for the 7 element or go with your Chinon recommendation :)
Cheers David. Yeah, unless you specifically want a radioactive version, there are plenty of other options. I went out of my way to get one because it's an interesting subject and I'm happy enough to use it, but I don't blame anyone for not wanting one of those sitting in their house. Another lens I really like is the Meyer Optik Gorlitz Oreston 50mm f1.8 - I've got some cracking shots out of mine and they turn up on ebay all the time - often with a free Praktica camera attached.
@@GrumpyTim Ooh, thanks for the tip. I'm still new to the vintage lens game so I'm eager to see what I can get my hands on. I'm really enjoying my Pentacon 50mm 1.8 and the Hanimar 135mm f3.5 both of which came with a Praktica super tl2 I was given.
@@DavidFlowerOfficial I think you'll probably enjoy most vintage lenses you pick up, sometimes the unloved bargains ate more fun than the ones everyone shouts about. Having just recommended the Meyer Optic Gorlitz Oreston, I suddenly seem to remember that it might be more or less the same as your Pentacon 50mm, maybe a slightly earlier version so possibly don't rush out and get one of those!
Great video! It has me wondering did anyone notice film degradation when a roll was stored for a period of time in a camera with a radioactive lens attached? There had to have been an effect but the cause of a degraded picture probably was not correctly identified. I also wonder how many campers changed the mantles in their lanterns not knowing to wash the dust from the old mantle from their fingers before eating, touching their mouth, etc. or if the dust from an old mantle got into their tent or sleeping bag. Thoriated tungsten filaments were used for years in automobile lights to increase their life.
I had wondered the same thing about old film cameras - I figured that there's the mirror, shutter curtain and a bit of an air gap between the back of the lens and the film which would reduce the exposure to the radiation to a certain extent - it wouldn't stop it completely by any means but it would reduce it a little. I'm guessing many of the radioactive lenses were the higher spec models and possibly more likely to be in the hands of professional photographers so the film might not hang around in the camera that long, but I'm fairly sure there would be some effect if you did leave film in the camera for long enough.
I do remember our old family caravan had gas lamps with those mantles - they were open to the air with only a glass diffuser round the sides but I can't remember ever seeing a mantle being replaced so maybe they lasted quite well.
Possibly it's a good thing we now know these items are radioactive and can take the appropriate care but I also suspect that in normal use, they're not too dangerous. Definitely my biggest worry would be inhaling or otherwise ingesting powdered material. I'd also be pretty wary of spending excessive time in very close proximity to them.
I didn't know about the thoriated tungsten filaments - I'll have to test some of the old bulbs we have kicking around!!!
I have the same lens and Geiger counter and it does make my drink like crazy too
Thanks
You're welcome :-)
İmpressive video. Thank you for the video. I have both lenses you show. I m gonna use chianon 55 mm f 1.4 much more than takumar. I don't cover the lens when I don't use. I m gonna use chianon on my DSLR when I keep my DSLR on my table. Thank you.
I very rarely use my Takumar, mostly because I store it in a box far in a corner of a room I don't go into all the time. It's an interesting lens to own, and great quality too, but I have others that are similarly good, which live in my "every day" camera bags, so those are the ones that get used.
Cheers for watching.
They are totally save and so much better than non radioactive lenses !!!! Just store them at least 1 meter away from you and don't use them 24/7 .
Cheers Robert - they are pretty amazing lenses. I've also got a Mamiya Sekor radioactive lens - the optics are in great shape but someone had obviously dropped it, causing the front of the housing to bend, which in turn stops the focusing mechanism from working - that one is still on the workbench until I get round to fixing it.
why they are better? can i get that vintage look with non RA lences?
@@elian3486 Thorium improves contrast in lenses, so radioactive lenses might produce a better image than some other lower quality or older non-radioactive ones. However, I don't know if there's a noticeable difference between a radioactive f1.4 and a non-radioactive one.
About your second question, no, it is not necessary to have a radioactive lens to have a "vintage look" in your pictures. I'd say a good chunk of old lenses have it, and some of them are quite cheap
@@cruzdesangre2850 there are videos on YT comparing the thoriated takumar 50mm 1.4 and a non-radioactive pentax M 50mm 1.4 (same lens, just for a K Mount). There was no visible difference, apart from the warmer tint produced by the radioactive lens.
I have a 50 year old Olympus M-System (later OM-System) 50mm f1.4 lens, and it is quite radioactive at the front, and negligibly radioactive at the rear.
Edit: I took some readings from the lens. With the GM tube as close as possible to the front element, 12.1uSv/hr. With the GM tube as close as possible to rear element, 0.6uSv/hr. With the GM tube at the same distance in front of the front element as it was from front element to the rear element in the rear element test, 3.1uSv/hr. This was at f1.4. I then placed a 3mm plate between the lens and the GM tube, and the reading dropped to 0.8uSv/hr. Background at my place is usually 0.16uSv/hr. The lens was wide open for these tests.
Hi Lungs, I haven't exactly done exhaustive testing, but I'd definitely heard that the location of the Thoriated elements can vary from one lens design to another, which makes sense seeing as though the optical design itself can be very different. That's a nicely executed set of tests, - as you prove there, you can gain quite a bit of knowledge about your lens with just a few simple tests.
Grumpy Tim....
yes the Super Takumar 50mm f1.4 lens is radioactive, but... have you ever heard of the FUJINON 50mm f1.4 lens? It is radioactive to the tune of 3706 CPM and get this... 22.77 uSv/h !!! They say that 100 uSv/h will cause you to start growing a third eye. I just bought this lens as was surprised to learn about the level of uSv/h it has.
Just checking in...
Hi Jim (or at least I presume it's Jim using a different account), I've heard of that lens but never seen one in the flesh - it must have a huge chunk, or even several huge chunks of Thoriated glass inside. Have you taken any shots with it yet - I'd be willing to bet that it's quite a nice lens optically. Definitely wouldn't be everyone's cup of tea though - not that a lot of people would even know it's radioactive, I know some people are pretty shocked when they find out the old lens they've been using for years is radioactive, but it would be even more of a shock to find out it's as radioactive as that!!!
I was reading one japanese website where a person overhauled the whole lens. The original Fujinon (all metal body, with silver apperture ring) and an early-style EBC Fujinon 50mm 1.4 (the short one, non-diamond rubber band) have 6 out of 7 elements made with thorium.
What's that icon in your gigar counter next to the speaker icon?
Hi Exploring new, that icon is supposed to look like a bell. It shows that the alarm is enabled - you can change the threshold at which point the alarm will sound, either for when the radiation reaches a specific CPM or when using it as a dosimeter the alarm will sound once you have been subjected to a specific amount of radiation and it's time to get out...
The other icon, to the left of that indicates that data saving is enabled, so you can download your radiation history to your PC.
What did I find out? 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 inch blocks of Plexiglass on the front of the lens. Using GQ GMC 320 Plus I was able to measure a drop from 3389 CPM to 540 CPM. Just think about what 2 inches of plastic would do. Now that is news.
Jim
Hi Jim, nice bit of testing there, thanks for doing the legwork. Also, exciting lens purchase - definite lens envy here. I bought a copy f the Zuiko f1.4 recently but I haven't even had time to try it on a camera yet - bit of a major project in progress so not much time for anything else at the moment.
I have one of those too. I bought the f1.4 first. f1.4 lenses are really "good enough". However, the f1.2 is even more lens and harder to use. You have about 8 mm in focus with the f1.2 lens wide open. You need a tripod. The trick it finding those few millimeters. Use a high sensor speed and a fast shutter speed because those few millimeters are a fleeting event.
I bought two f1.2 lenses in the last couple of weeks.
Both lenses are in Excellent shape, but I can tell that using a f1.2 at wide open is not what most like. The depth of field is like 8 mm. When does someone need that? I am thinking it will help me with product photography, maybe. "I think the f1.4 is the most practical for narrow depth of field." However, I could not resist the deals I saw. The Olympus came from Japan. The Canon FL came from here. I had bought my Olympus f1.4 from him a few weeks before and he cut me a deal. It is winter and lenses are my winter past time, I guess. It is too cold to go into the recording studio. If you heat the studio up, the strings stretch. When the room cools, the strings tighten. It is impossible to stay in tune. Olympus OM-System G.Zuiko Auto-S 55mm f1.2 1974 Radioactive 3389 CPM lens for $256
and
The Canon FL 55mm f1.2 Fluorite Lens elements 1968 (1.05822 lbs) for $100.
I like the FL better so far, but I am sure they are both going to be big hits here.
The FL is only good up to maybe 6 feet away with a cheap FD adapter.
What is needed here is a conversion kit that will recess the lens by 6 mm and then focus out to infinity.
I am not who has them at this point.
You need to read up on Fluorite glass.
Jim
Hi Jim, yeah you're right, I definitely don't NEED an f1.2 lens, it's just one of those that I'd kind of like, because I've never tried one. For most stuff I don't even use my f1.4 lenses wide open, but they're definitely a nice thing to have around. Thanks for all the added info.
I have used a f1.4 a lot in my product photography at a distance of 20 feet. The depth of field works out then. Sometimes I use 5 feet. You can see these photos on my website here. Make it one word. Then use the com extension. "audio gear for the artist"
The console photo is from 20 feet. The rest are 5 feet.
I was using the Asahi Super Takumar 50mm f1.4 lens there.
Let me know if you can make this work.
Jim
I have a SMC takumar (7,2 uSv/h directly at the element) and its always on my EOS R7 via a EF RF filter adapter. No damage so far, also the camera or adapter itself got not (yet?) radiated itself.
If the camera or sensor ever take damage it was for science. I heard about 500mR an average modern pixel can "consume" before the sensor really takes damage. thats basically more radiation resistance than a human.
To measure a banana you would need at absolutely least a Radiacode 101, better the newer 102. But this device really tells you within a few minutes its decay is from Kalium 40. Its primary function is that its not only a regular (and fast and relatively precise) geiger counter but also a gamma spectrometer.
With a few more years of information I'm inclined to think that IF the radiation was going to cause any damage to the sensor, it would take a very long time, probably well beyond the expected life of the camera, but I'm really glad you're conducting a proper test, great stuff. I knew the banana would show nothing on my Geiger counter, it was just an amusing bit to add to the video, that said, it would be fun to have better testing equipment that could detect banana radiation!
@@GrumpyTim If i would really need it i would have a radiacode already, but about 300$, despite being not too much is somewhat too much for my "needs", hell i dont even need this "cheap" geiger counter anymore, i needed it like 3 days in the chernobyl exclusion zone longer ago (with stalkers, no official tour where you get them anyways)
Yep, it's the same with me, I don't really need anything more exotic than the simple geiger counter that I already have - it's handy for checking old stuff like clocks and anything else with luminous paint before I charge in and start repairing it. Coo, you've been to Chernobyl, I always fancied visiting Pripyat for some cool photography (not that I'd be the first to have that idea), but it seems a little less likely nowadays.
@@GrumpyTim yeah i think the stalker days are gone in pripyat i would not wonder if there are now a lot of butterfly mines (laid by russians as well ukranians!)
Yep, definitely an uneasy time for everyone over there.
The neutrons they do have a charge but it 0+ know as neutral charge it’s very hard to explain this as you will get into quantum mechanics but in simpler terms neutrons have a charge but it’s 0+ due to counter balancing and Like all hadrons, neutrons are made of quarks. A neutron is made of two down quarks and one up quark. One up quark has a charge of +2/3, and the two down quarks each have a charge of -1/3. The fact that these charges cancel out is why neutrons have a neutral (0) charge. All this information I got from Geiger Fever he is so good at explaining and reviewing Geiger counters you should all check him out he is great
Cheers Luxury Culture, I'll check out Geiger Fever, that sounds good.
I wanted to keep my physics lesson very simple in the video, it was really there just to give a basic idea of why these lenses don't just release Alpha particles (as is often mis-quoted) without getting too bogged down in complicated stuff. I wanted to demonstrate in a fairly simple way how radioactive the lenses are in relation to some other common household items - none of the tests I did could be classed as accurate scientific data, but they do give an indication of the relative radioactivity.
Cheers for the comment :-)
You're genious, lovely vid! 👍
I have too the GX80 😊
This lovely Geiger counter isn't available, do you know how can I get it, or which one instead? Thnx
Hi Antal, how right you are, there seem to be none of the GMC geiger counters on Amazon any more - I don't know if that's because they're out of production at the moment or whether people have been buying them in case of of an escalation in current troubles around the world. I have no experience of any of the other ones available on Amazon at the moment. I would expect to pay between £80 and £100 sterling for an entry level geiger counter, any less and I'd be pretty wary.
The best advice I can give would be to search on TH-cam for something like "Amazon geiger counter" and see what people are recommending.
@@GrumpyTim
You're amazing, thank you! 👍
Hi Antel, I know it's quite a while since your first message, but Amazon do appear to have the next model up, the "GMC-320 Plus" available at the moment - here's an affiliated link if you're still interested amzn.to/3NzrDwe
Amazing video! I find your video very interesting, I have two of this lens store in my room 10 feet approx (3 metres away from me,( in a camera bag ) do you think I have to put them in another room ?? Thanks!
Hi Rodrigo, at that distance of 10 feet away, I think you'd be hard pushed to detect any increase over background radiation levels (even using much better equipment than I did in the video), so, from all the research I have done, I would say that you don't have to worry. People have differing levels of worry/panic/hysteria regarding radiation, so if you do suddenly find yourself worried about your lenses, then sure, you can move them to another room.
Using these lenses at close range occasionally (ie taking photographs with them) will add a tiny tiny bit to the amount of radiation that your body receives over it's lifetime, so theoretically they could very very slightly increase the risk of cells mutating, but that really has to be put into perspective. The small increase in radiation dose will be localised around where the lens is positioned whereas if you go on a transatlantic flight (or any other flights), your whole body can be subjected to an increased dose of radiation for the duration of the flight. The same applies if you happen to live in one of the areas of the world where background radiation levels are higher, then your entire body will receive a higher dose of radiation all day, every day.
Generally these lenses can be thought of as safe to use but it's always worth being aware that they are radioactive so don't sit on them all day every day (your 10 feet away should be fine) and probably most importantly, don't grind the glass into a powder and breathe in that powder - inside the body there's nothing to block the radiation, it will be in there, right up against your organs, where it would be far more likely to cause cell damage.
Hope that helps.
@@GrumpyTim thank you very much!! 👍
@@GrumpyTim thank you very much! 👍
Do you take any precautions when storing your radioactive lenses? I have three
Asahi Super-Multi-Coated Takumar 55mm f1.8 750 CPM
Asahi Super-Multi-Coated Takumar 35mm f2 1850 CPM
My Asahi Super Takumar 50mm f1.4 reads 2250 CPM
A friend of mine started a company that built geiger counters.
She suggested that I take precautions when storing them together.
Hi jmoss99, I don't specifically take precautions in storing the single radioactive lens that I own (I thought I owned two of them until my Geiger counter told me otherwise because my Yashinon lens showed no increase in radiation above ambient levels), having said that, I don't store the radioactive lens with my other lenses - I keep it in the corner of a room where the closest I'll ever get to it is about 4 feet away (unless I'm using it). Maybe, if I didn't have the luxury of storing it well away from me, I might think about building a radiation proof box to keep it in - not so much because I think it will be terribly dangerous but more for peace of mind.
If I was building a box to keep radioactive lenses in, I would make sure I researched the subject thoroughly - typically, people think of using a lead lined box to stop radiation escaping but, there is a phenomenon called "Braking Radiation" or "Bremsstrahlung" given it's German name, where high energy beta particles can hit the lead with such force that the lead decays and emits gamma radiation. To prevent this, the beta emitter should first be surrounded in something else and then the lead on the OUTSIDE of the box. I believe Perspex is sometimes used as the inner layer with the lead on the outside but I haven't yet done enough research to confidently recommend an exact method of construction for a radiation proof container. This information about braking radiation may not apply to these lenses - I've read about it more in connection with P32 which is a very high energy Beta emitter, but without definitive information to say that it doesn't apply, I'll assume that it might. Additionally, if I was making a box, I'd probably make a multiple layer container with Perspex on the inside, then aluminium, then lead and finally another material such as wood on the outside (just so it was nice to handle). Probably way over the top for these lenses, but if I was doing the job, I'd want to do it thoroughly!!!!
Hope that sort of helps, sorry it's not a definitive answer, but with the slight query about Braking Radiation, I wouldn't want to recommend just a lead lined box.
Perspex or here called acrylic, does not have any effect on the radiation. I just tested it.
Yeah, I had previously tested acrylic (not specifically Perspex which is a brand name as far as I'm aware, but another generic brand of acrylic), I also tested polycarbonate sheeting and saw no significant reduction in the quantity of radiation that I was reading with either material - at that point I headed into "hunch" territory so there would need to be more investigation, but my hunch is that the Perspex/acrylic or whatever doesn't block the particles but it slows them down (or reduces their energy) enough that the Braking Radiation phenomenon doesn't take place - I must stress that this is just my hunch and I don't have actual proof of this.
My belt and braces thinking if I wanted to make a radiation proof box for these lenses was: Use acrylic as the inner layer (in the assumption that it slows the particles), then Aluminium because that IS supposed to block Beta particles (not just a bit of kitchen foil - I did read somewhere about what thickness of Aluminium you need but I can't remember where so I figured I'd use a 1 or 2mm layer, then a layer of lead and then finally my outer layer of wood/plastic or whatever. Again, this is "hunch" science and not anything that I have absolute and accurate information on at the moment.
I guess it would be interesting to try to make a "safe" box, but then I'd potentially want to find someone with a much more sensitive Geiger Counter and maybe even test it in a radiation proof room to see if it was 100 percent successful.
Let me know if you make a box or enclosure, I'd be interested to hear.
hey great video, could you give me a little help? do you know if Pentax-M SMC 50mm 1.7 and nikkor af 35-80mm f/4-5.6d are radioactive? i know pentax was released in 1977 and nikon in 1993, i suppose in 90s they stop to make this radioactivel lens, am i right? but this pentax i have, im a little worried, i dont find in internet so much about, but im suppose if is radioacvtive its not gonna be so much like takumar?
Hi Gabriel, cheers for the question - I've never used or tested either of these lenses myself so I can't give an absolute answer, but, there's a list of radioactive lenses at camerapedia.fandom.com/wiki/Radioactive_lenses - I don't know how accurate the list is but assuming it is accurate and up to date, lower down the list is the section for NON radioactive lenses and this includes the Asahi SMC Pentax-M 50mm f1.7 so it could well be that your Pentax isn't radioactive.
As for the Nikkor 35-80, if it was made in 1993 I'd be amazed if it was radioactive, I'm sure by that time they'd figured that maybe adding radioactive materials to the glass wasn't such a good idea.
The only way to be totally sure is to check them with a Geiger counter.
Even if the Pentax lens is radioactive (which it probably isn't), you can still use it, but for total peace of mind you might not want to keep it close all day, every day - for occasional use it will be totally fine.
@@GrumpyTim thanks for your help, recently i bought a pentax me and now i got a nikon fm2, and i'm looking for a 50mm lens to use in my nikon and then i'm realized in the existence of radioactive lens, and i think the old nikon lens are better than the plastic lens (at least cheaper here in brazil the AI-AIs lens), so i was a little afraid of buy a hot lens, but how do i use this cameras something like once a week for like 2-3hour, wont gonna be a big problem for me. But just another question for curiosity, have you ever heard about radioactive lens out of youtube/internet? it's look like this big companys dont talk much about, i'm suposse has a lot of people who has radioactve lens in house and have no idea about
2:45 just letting you know the number of protons doesn't necessarily equal the number of neutrons for an isotope to be stable. as you move along the periodic table you actually need more neutrons than protons for stability
Thanks Pupper, I tried to keep the physics lesson as basic as possible, otherwise that could be a series of videos all by itself. I mostly just wanted to give a rough idea of what radiation is and how much there was in relation to other relatively common objects.
It's funny how many other objects I've discovered from my childhood that are fairly radioactive - today's discovery (thanks to another TH-cam channel) was a vintage electrical switch with a luminous dot on the top - the Geiger counter gets pretty excited when placed next to said switch!!!
@@GrumpyTim it was still a very good explanation though :D
ooh thats pretty cool. maybe radium?
Yeah, I would expect it to be Radium in the luminous paint - I really should link to the video where he tested a similar switch to mine, so here it is th-cam.com/video/Q7uyF35gL7I/w-d-xo.html
Thanks for the comments and info.
I've been shooting with my newly acquired Super Takumar 50mm 1.4 for the past three days. If I had seen your video essay sooner I would not have let it on the camera all this time. The sensor recovers, doesn't it? once the lens is removed?
Hi Richard, don't panic - you won't have done any harm to your sensor. There's background radiation hitting your camera sensor all the time. The increased radiation hitting the sensor when the Super Takumar 50mm f1.4 is attached, could potentially speed up the ageing of the camera sensor, but that is only my hunch and not based on any scientific evidence (it would be interesting to do a controlled test - for instance, buying two identical cameras, fitting one with a Super Takumar and the other with a non radioactive lens and then leaving them for a year to see if there was any noticeable effect on the sensor of the one fitted with the Super Takumar, but that would be a bit of an expensive test to carry out, so it's not for me!).
For my own peace of mind I don't leave the Super Takumar on my camera when it's not in use but I would guess that you'd need to leave it on the camera for a few years to notice any detrimental effect, if indeed there was any detrimental effect at all.
The increased noise you saw when I did a long exposure shot with the Super Takumar fitted to the camera, shows that the lens has some effect on the sensor, but it's only activating some pixels, as if there was a little bit of light hitting them.
You should be fine to carry on enjoying using your new lens (they really are a fantastic lens), just be aware that it IS mildly radioactive and maybe don't keep it close to you ALL of the time.
@@GrumpyTim -- thanks for your prompt and excellent response.
Try wrapping the lens in a lead foil just to prove if it is effective to store this lens at home in this way.
Hi Dr Jorge Driottez, funnily enough, I made myself an enclosure earlier this year, to house the two radioactive lenses that I own. The construction of my enclosure was 1.2mm of Aluminium on the inside, then 10mm of chip board, followed by 2.6mm of lead and finally 6mm of plywood on the outside. Although it does reduce the radiation, it by no means stops it completely. As with the tests I did in the video, by the time the lens is about a foot or so from either of my geiger counters, I can no longer detect any radiation.
I've heard the later "Super-Multi-Coated" version of the Takumar 50mm /1.4 is more radioactive because radioactive elements were used in the coatings as well as in the glass. Do you know anything about this, or have one to test?
This was a very fun and informative video. Thank you for making it.
Hi Danny, I've heard the same thing about the later "Super Multi Coated" version of the lens but I haven't had one in my hands to test. I would assume that it IS correct that they are more radioactive because I've heard that from many sources but I don't know about the radioactive coating part - it could well be true but as far as I was aware, the Thorium was added to the glass to lower the dispersion of the glass, a job that it did very well - the coatings are mostly there to reduce unwanted reflections and I don't know if the addition of radioactive material would help with this (someone out there will know). It could just be that more of the elements were radioactive in the Super Multi Coated version - it's just the back end of my lens that's radioactive but I've heard that some lenses have radioactive glass in the front elements too.
@@GrumpyTim Thanks for replying and giving your insight! I hope one finds its way into your hands one day so you can run some tests
Cheers Danny, I'll keep my eyes peeled.....and also for the early eight element version which tends to fetch a fairly high price.
Does the radiation remain in the place or container where it was left for a long time? Or does it disappear from the area once the lens is moved?
Hi myroombirdblack, rather handily, as each atom decays and emits it's radioactive particle, that particle just flies off and vanishes, so you don't get left with radioactive stuff, it's only there when the lens in this case, is present. It doesn't make whatever it's sitting next to turn radioactive.
Other radioactive materials such as radioactive Caesium are, to a certain extent, soluble in water, which means they can be absorbed into soil and water courses and so on. I believe much of what came out of the Chernobyl accident was radioactive Caesium, hench the slight problems it caused.
I would say not great, not terrible :D Is there any way of storing it in isolation, so that it doesn't affect the environment at all when sitting in the drawer?
Hi Marcin, there's quite a long answer to that question: The radioactive particles emitted by the lens don't travel very far - by about a foot away you can read little more than background radiation, so theoretically, keeping the lens a couple of feet away from anything else would do the trick. When the lens is close to other objects, it doesn't magically turn the other objects radioactive so you won't suddenly have a drawer full of radioactive things.
However, the radiation would/could fog old camera film, if left in close proximity for long enough (kind of bizarre seeing as though that is EXACTLY what you'd expect to do with a camera lens), and, as seen on my video, the radiation will also effect the images on a digital camera sensor by adding noise. I have no specific proof that the radiation could maybe prematurely age certain objects that it's in close proximity to but, as a precaution, I store my lens in a basic lens case, on a window sill, away from anything else (this is probably unnecessary but that's what I do anyway).
As for making a specific radiation proof box for the lens, things get a little more complicated. Typically, people think of using a lead lined box to stop radiation escaping but, there is a phenomenon called "Braking Radiation" or "Bremsstrahlung" given it's German name, where high energy beta particles can hit the lead with such force that the lead decays and emits gamma radiation. To prevent this, the beta emitter should first be surrounded in something else and then the lead on the OUTSIDE of the box. I believe Perspex is sometimes used as the inner layer with the lead on the outside but I haven't yet done enough research to confidently recommend an exact method of construction for a radiation proof container. This information about braking radiation may not apply to these lenses - I've read about it more in connection with P32 which is a very high energy Beta emitter, but without definitive information to say that it doesn't apply, I'll assume that it might.
Hope that helps a little.
Hi :) Sorry to bother you again, but do you happen to know if the Minolta md 28mm. f2.8 is radioactive? Thanks :)
Hi Cofake-1984, I don't know for absolute certain but, from what I can see, the Minolta MD lenses appear to have been introduced around 1977 - I think by that time most of the radioactive lenses had been phased out.
Was planning to use these on my expensive arri alexa now i just cancelled my order on ebay. All thanks to you cannot take risk on the sensor
Hi Mansh, that's interesting, I hadn't thought about using one of these lenses on something really expensive like that - it may well be fine, but I agree, it seems maybe a bit of an unnecessary risk - I won't leave the lens on my Lumix GX80 when I'm not using it, and that's pocket money in comparison. Thanks for the comment.
@keketonttu
Hi, excuse me, one question. Is this Yashica ML 50mm 1.9 model radioactive? Regards!
Hi Pablo, the only Yashica lens I've tested is the 5.5cm (in other words 55mm) Yashinon f1.8 which I've had since I was a kid, and that one isn't radioactive at all. I know some of the earlier Yashinon lenses are radioactive but I would suspect that your version isn't.
@@GrumpyTim I hope it's not, because I almost completely disassembled it to clean it and even scraped a few joints to try to separate the lens. I don't have a meter and I would like to find a video of the Yashica ML 50mm 1.9 lens in which they measure its radioactivity to know that I was not in danger by disarming it.
Hi Pablo, from what I can see, looking at the following website yashica.boards.net/thread/1011/yashica-ml-lens-timeline - your Yashica ML 50mm f1.9 was introduced in 1985, and by that time I'm pretty sure all manufacturers had stopped producing radioactive lenses. I'd have thought that you'd be pretty safe with anything made in 80s. I've not seen anyone suggesting your lens is radioactive. The Yashica DS 50mm f1.7 appears to be radioactive (or at least some versions are).
Hope that helps.
Hi, I’m thinking of buying a Canon 50mm f0.95 Dream Lens, does anyone know if it is radioactive? Apparently canon used rare earth glass, not sure what that means. Thanks
Hi Shahram, I hadn't heard of that lens until I read your comment - wow that's an interesting lens. I haven't heard people talking about that lens as being radioactive (usually if a popular lens has been tested as radioactive you'll find out with a simple google search). I suspect the rare earth glass means that they used Lanthanum in the glass. I've never done any research on Lanthanum, I remember reading somewhere that it could be radioactive under certain circumstances, such as if it was poorly refined before being added to the glass, but that is not something that I've investigated myself.
My hunch is that the Canon 50mm f0.95 dream lens is either non radioactive or only very slightly radioactive, but that hunch isn't based on any actual knowledge of that lens.
Sorry that wasn't much help, but at least you can now go and read all about Lanthanum to see if that helps!!!
Thank you so much for your reply! I actually use to have one awhile ago and sold it, but I’ve decided to buy another one, as the rendition of this lens is very unique. I remember that the glass against a white background was clear, but had a amber coating to the rear and front elements. I know in the advertising for the smaller version of this lens the Canon 50mm 1.2, it stated proudly that rare earth glass was used. I think you’re right it’s more of a Lanthium type lens than thorium, as it would have had yellowing in those big elements.
Thank you so much for your reply
That GMC-300E isn't effective at measuring Alpha and Beta in small quntities. I have 2 of them, and 1 GCA-07W
Hi James, yeah, I acknowledged that the 300E isn't any good for detecting Alpha in the video - for that I'd need a probe with an open ender chamber and mica window (or something along those lines) - your GCA-07W would do the trick. The 300E was good enough for the purpose of this video though - to give an idea of the relative radioactivity of some common items you might find in the home. The tests I did wouldn't be good enough for laboratory use but that wasn't the purpose of the video - there's so much mis-information about these lenses "the radioactivity is only the coating" and "they ONLY emit alpha waves" (yes, I have seen the Alpha emissions referred to as "waves") are two that I've read so many times - I just wanted to make a balanced video that didn't set out to scare or over dramatize what is, for most people, a pretty complicated and confusing subject.
Hey Tim
I just bought this lens and I have two doubts:
Do you have any recommendations for storing the lens? I rent a room to sleep and I keep my lens inside a wooden crate 7 feet from me.
There is a way to remove the amber tint with UV, but I guess the radiation would still be emitted, am I correct?
I hope you can answer me, thank you very much Tim!
Hi CupHead, from all the measurements I took, storing the lens 7 feet away from you should be fine. But if you were worried, you could always put the wooden box inside a metal box, or depending on the size, put the lens in a metal box and place that box in the wooden box - the more material there is between you and the source of the radiation, the less radiation will get to you - some radiation containment methods involve lots of concrete - it's the quantity and density of the concrete (along with some lead) that reduce the radiation levels. If you do use lead, always put another material between the lens and the lead such as some aluminium or acrylic material like perspex.
Yes you can often remove the amber tint - I've heard about people using UV, although from what I've read, it's actually the warmth from the LED light bouncing back off some silver foil on the other end of the lens that actually does the de-yellowing rather than the UV. However, this will make no difference to the amount of radiation emitted.
My own opinion is that you should be fine keeping the lens as you do because at that distance, the actual increase in radiation that you'll receive above the normal background is negligible.
@@GrumpyTim I really appreciate your detailed explanation. You are one of the few content creators who take the time to respond to comments and questions about your videos.
Thank you very much from everybody!
Thanks CupHead, hope you enjoy your lens, they're pretty awesome.
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 inch blocks of Plexiglass on the front of the lens. Using GQ GMC 320 Plus I was able to measure a drop from 3389 CPM to 540 CPM.
This is such a coincidence that I came across your video, as I was greatly stressing about this recently. It came to my attention that a few of my lenses and cameras (a Yashica Electro 35 GX, and potentially some of my Minolta lenses) may be radioactive. I’ve stored them under my bed in a case for years. It really worried me. I know you can’t say for certain, but how great of risk did I put myself in? I recently bought a Pen F and saw the glass is thoriated, which makes me not want to use it. :( They are far away from me now!
Hi Robert, the first thing I'll say is DON'T PANIC - even if some of your lenses are radioactive, the radiation level decreases rapidly the further away from the lens you are - even about a foot or so away from my lens I couldn't detect anything more than background radiation levels. Radiation levels will also reduce as they pass through other objects, particularly dense objects - your bed frame and mattress aren't exactly dense so they wouldn't block the radiation but they would have a nominal effect on reducing the amount that got to you.
I expect that if I put my Geiger counter (which admittedly isn't the best or most sensitive Geiger counter in the world) on your mattress with the lenses in the case below, I wouldn't be able to detect any increase in radiation.
It would be fair to assume that a tiny bit of additional radiation from the lenses did get to you but probably far too little to worry about. There's radiation all around us all the time which is the background radiation but it's not a lot so we don't really need to worry about it - lets say that your lenses under your bed doubled the background radiation levels when you slept (it wouldn't be anything like that much of an effect in reality - it probably only added a couple of percent) - twice not a lot is still not a lot.
I'm generally over cautious so I would do what you've done and move the lenses to a new location and then not worry about it any more.
You can still use your camera and lenses - The highest levels of radiation I measured from my lens were pressed right up against the rear element, but in normal use, the radiation dose I measured at the back of the camera was only about 8 times background radiation, and 8 times not a lot is still not a lot.
I live in a relatively low background radiation area with around 0.15 to 0.3 Micro Sieverts Per Hour - (which we'll refer to as uSv/h from now on) but there are places where background radiation is higher - there are areas of Cornwall for instance where the levels are higher because the rocks in the ground contain more radioactive minerals but people still live there.
If you fly in a plane, high in the Earth's atmosphere you're exposed to greater levels of cosmic radiation because there is less atmosphere to absorb this radiation - up in a plane you will be receiving a dose of 3.0 to 4.0 uSv/h (this is based on other people's information, I haven't measured this myself but it appears to be about right).
The dose rate I measured at the back of the camera was 1.15 uSv/h, which doesn't suddenly sound so scary when you consider that a pilot will be making many flights per year and the dose they will be getting is a whole body dose, whereas the dose from the radioactive lenses is much more localised.
There's a list of radioactive lenses at camerapedia.fandom.com/wiki/Radioactive_lenses - I've no idea how accurate the list is but you could check to see how many of your lenses are on the list.
Also, if you were worried/interested, Geiger counters like mine are surprisingly affordable from Amazon, and it can be quite fun going round your house finding out how many things are radioactive.
Hope that sort of helps.
@@GrumpyTim It absolutely does, thanks! Seriously, the back and forth on forums had me really fretting. I think I will pick up a geiger counter, sounds like a fun distraction while also putting things into perspective. Thanks again!
Hi Robert, radioactivity is such a complex subject, it can be a bit overwhelming, and there's a lot of incorrect or at least misleading information out there. One of the difficult things is evaluating how dangerous a particular level of radiation is. As a general rule, it's the accumulative effect of radiation over your lifetime that you need to worry about (or at least when referring to the relatively low levels we're talking about here - the guys who first attended the Chernobyl disaster were hit by so much radiation that the effect was pretty rapid). Using things like these lenses will slightly increase your overall lifetime radiation dose but it really is a tiny increase so isn't really worth worrying about. However, it is at least worth being aware that they are radioactive and treating them accordingly - the biggest risk would be to manage to smash the glass so it became tiny fragments that you could breath in - once in the lungs, the fragments could have a much greater effect.
Having a Geiger counter is quite interesting - depending on the sort of stuff you have around your house, you might find a fair few things that are radioactive. There was Uranium glass, used for decorative glass objects, it was even used in some glass marbles - when I was a kid I swallowed a marble - by accident of course - I dug out my marbles when I got the Geiger counter but sadly none of them were radioactive because that would have been such a good story if I'd swallowed a radioactive marble!!! Fiesta ware Red is another radioactive product - to get the vibrant colour in the glaze they added Uranium (or at least I think it was Uranium - I haven't got my notes with me today) which made the plates, cups, bowls etc fairly radioactive. Old watches and clocks are often radioactive due to the Radium that was used to make the luminous paint glow brighter and for longer - bizarrely, now, the part of the paint that glows has long since lost it's effectiveness and they hardly glow at all - you're just left with a splodgy looking dull paint that's radioactive. The thoriated mantle on the old lamp I showed in the video is probably the biggest health risk - the brand new mantle is ok because it is very much intact, but once they've been used, the y become very fragile and will break into dust if knocked - it would be all to easy to be restoring one of these lamps and unknowingly blow the dust using an air line, creating a cloud that you could inhale. But there are other risks associated with old things like that lamp - the wick at the bottom of the burner stem will almost undoubtedly contain asbestos which could again be a risk for an unsuspecting restorer.
Hope you have lots of fun measuring stuff if you do get a Geiger counter.
I wouldn stress about a lens. The poluted air and food are more of an issue IMHO
Have you tested whether looking through the lens using the mirror/prism of a standard SLR would expose you to more radiation? If that's the case, it seems like you would only want to use this with mirror-less cameras like your Lumix
I haven't actually tested the lens on a traditional SLR - I could easily do that but I wouldn't expect to see that much difference. The radioactive particles emitted by the rear element of the Takumar won't act like light, reflecting off the mirror and passing through the prism into your eye (the radioactive particles will travel more or less in a straight line, in all directions, from the rear element, passing through bits of the camera as they travel). The distance between your face and the lens will be similar on an SLR camera, and as the radioactivity reduces over distance, that part of the effect should be similar.
The other thing that will reduce the amount of radiation that gets to you will be the materials that the particles are passing through - the more stuff the particles have to pass through, the less actually makes it through so if there's actually more solid stuff in an SLR, you might receive a lower dose than on a modern mirrorless camera. Concrete is used for radiation shielding, not because sand, cement and gravel specifically block the radiation, but because a large amount of dense material does.
Radioactivity is a really complex subject - I tried to make the video relatively accurate and informative but you could probably spend years at university and still not know everything. There's bound to be parts of my information that could have been improved.
Another little side note I found out after making the video was about breaking radiation which has the German name "Bremsstrahlung" - I found this out in reference to P32 which is a very high Beta emitter - largely, people will tell you that you can use lead to block radiation, this is largely true but with a high energy Beta emitter, the particles can knock into a lead atom with such force that the lead decays and emits Gamma radiation, so the thing you are intending to use for shielding actually becomes an emitter itself. To prevent this, the P32 is stored in a perspex container which reduces the Beta enough so the perspex can then be surrounded safely by lead. I don't think this phenomenon will particularly apply to these lenses but it's just an example of the fact that radioactivity is a complex subject - and if I was making a box for radioactive lenses, I wouldn't just make it out of lead!!!!
@@GrumpyTim Thank you for the detailed response! That's very interesting, and it makes sense that the radiation wouldn't act the same as light. It seems riskier to have lower density materials shielding your eye, but I'm sure you're right that it's similar to a mirrorless. Are you going to do a build video for your radioactive lens case?
I'm not particularly planning to do a video of making a case for the radioactive lenses - only because it'll probably be ages before I get round to making anything - it's not at the top of my "to do" list!!!
Radiation does not reflect in a mirror (unless it's light). The radiation from the lens will pass through the mirror diagonally to you in the same way that it will pass right through your mirroless camera. In fact your mirroless camera will be a little thinner than a SLR so less radiation would be absorbed by the camera body and innards (this also depends on the density of the materials used).
I doubt there will be any significant difference between the two however.
While I agree that this kind of radiation is not so dangerous for normal usage, I wonder if there is a major health risk by inhaling small amounts of radioactive coating if you dismantle the lens and clean it.
Hi Mindtravelness, good question, here are my thoughts:
The Thorium was added to the glass to improve it's optical properties - it's added into the mix of molten glass during manufacture so it's actually a part of the glass itself. I have often heard people saying that the coating is radioactive, but as far as I'm aware, that is not the case, BUT I don't know with absolute certainty that some manufacturers didn't use radioactive elements if the coatings as well.
On the subject of cleaning, if during the cleaning of any lens you are managing to remove some of the coating, then either the coating has become damaged / degraded in some way, OR your cleaning method is far too harsh and you're damaging the lens - for instance, if you use a car windscreen cleaner to clean a lens, such as Autoglym car glass polish which is abrasive, then you'll definitely be polishing off the thin coating and also leaving the surface of the glass with tiny scratches, which will affect the lens in an adverse way.
For my final thought, if some lens manufacturers did indeed use radioactive elements in the coating of a lens, and that coating degraded in such a way that it was flaking off, then that would be the worst case scenario that I can think of, because loose flaking coating fragments could easily be inhaled and we definitely don't want radioactive material lurking in our lungs.
Overall, my recommendations remain the same - these lenses are safe enough to use, but I would never want to force anyone who wasn't sure about them to use a radioactive lens - there's so many other options available, if someone is not happy, then just steer clear of them completely. I would always recommend treating these lenses with respect and be aware that there could be a tiny, tiny risk of increased exposure to radiation over your lifetime, if you kept one (or several) of these lenses close to you at all times, but there are other things you could do that would that would cause a far greater increase in your lifetime exposure to radiation than using these lenses.
Hope that somewhat rambling response sort of answers your question.
@@GrumpyTim Thank you so much!
I have bought a 55 1.4 Chinon that has a yellow rear element, so I thought maybe it is radioactive. Does your copy have a yellow rear element? My serial number is actually 109424, so it's ten pieces apart, haha :)
Wow, that IS virtually made at the same time as my copy!!! If I look through my copy of the Chinon 55mm f1.4 at a sheet of white paper it doesn't significantly change the colour of the paper, but if I glance at the rear element at a slight angle it looks yellowish - this is just the coating and doesn't mean it's radioactive in this case. I also have a Yashinon 55mm f1.8 which looks even Yellower when you glance at the rear element - I thought this one was going to be radioactive but it turned out to just be the coating.
On the other hand, when I look through the Super Takumar at a sheet of white paper, the white paper looks significantly yellowish brown.
I'm hoping that someone can help alleviate some concern for me. I own one of these Super Tak 50mm, with a small scratch on the back element. Does this scratch pose an immediate threat to become airborn at any time (with wear and time) or would it require some force to be applied to it to further damage the glass, to become an airborn threat at risk of being inhaled? I'm wondering if I should get rid of this lens based on that.
Hi Jason, assuming the scratch is just a small scratch, then it's not so likely that any bits of glass are going to fall off. If there are some flaky looking fragments of glass around the scratch you could potentially dab at the back of the lens with something like BluTack, which should remove anything that's likely to fall off - if your BluTack is new and clean, it shouldn't leave any marks on the lens. If you are planning to clean the lens, the BluTack trick might be a good idea before you clean it, because, if a tiny fragment of glass came loose, it could drag round on your cleaning cloth, causing even more tiny scratches. It goes without saying, if you do remove any fragments, wrap up the blob of BluTack and dispose of it.
Jason, on the Super Takumars, it is not the rear element which contains thorium, but one of the inside rear elements. A scratch on the rear element poses no radioactive risk.
Hi Jon, thanks for that brilliant nugget of information - that should put Jason's mind at ease and allow him to enjoy using a fantastic old lens.
@@GrumpyTim I do appreciate the replies all. I've actually bought a meter and checked my copy of the lens. The 8 element that I have is NOT radioactive at all. I have an early serial number so I lucked out. Going to measure all my vintage glass then return it to Amazon 👍
Excellent, cheers for the update Jason, and well done for having one of the sought after 8 element versions - no lens envy here at all!!!!!
Thorium decay chain also emits gamma particles alongside alphas and betas. See: pubs.usgs.gov/of/2004/1050/thorium.htm
Cheers Michael, I'll take a look at that article as soon as I get a chance. Radioactivity is a fascinating subject with so much information to explore :-)
@@GrumpyTim Indeed. I'm also armed with a Geiger counter, some radioactive lenses and a lot of enthusiasm when it comes to this topic.
Hi Michael, it's weird, as a kid I was taught that radioactivity was a dangerous thing which should be avoided - probably not a bad generalisation but possibly prevents learning about something quite fascinating and also it creates a terror of all things radioactive. I'm not planning to become over complacent about handling radioactive items or substances but it's certainly interesting finding out about that things we may already have in our homes that are radioactive - particularly for people who have lots of old stuff like clocks, watches, lenses and even ceramics in the case of Fiesta Ware.
Hope you have lots of fun with your Geiger counter - it would be great to go round an antique shop armed with Geiger counter to see how many things made it tick!!!!!!
So... What I gather from this video, these lenses are safe to shoot video, which is what I usually do, anyway. Just don't hold it next to your face.
Hi Major Tom, even holding one of these lenses close to your face for a limited time probably wouldn't really present much of a risk. We're exposed to low levels of radiation all the time, it's all around us. The overall dose of radiation we receive over a lifetime can take it's toll on our body and can increase the risk of developing cancer. Using one of these lenses occasionally will add a tiny tiny bit to that overall dose of radiation so therefore could increase the risk of developing cancer a tiny tiny bit. However, there are other things we do that will increase our overall dose of radiation, such as flying in an aeroplane, where we receive a higher dose of radiation over our entire body, not just a small part of our body. Or simply living in an area which has a naturally higher background radiation level, where again, we'll be receiving a higher dose over our entire body, all day, every day.
Radiation levels fall off rapidly as the distance from the source increases, so once you're a bit over a foot away from the lens, there's no measurable increase above background radiation on my geiger counter. So it's only when you're actually using the lens that your body will see that slight increase in it's radiation dose.
However, it's worth taking some care with these lenses, there's no point in being totally complacent and holding the back of the lens right up to your eye or face, because that's an unnecessary additional dose of radiation. Where these lenses could actually present a real risk would be if you ground the glass up into a fine powder and inhaled the dust - that dust would remain in your lungs, without distance or even your skin to reduce the radiation (skin can reduce the amount of alpha particles that penetrate the body). With the radioactive glass dust in direct contact with your vital organs, cell damage would more than likely occur, and the risk of developing cancer would increase.
Correct, with radiation, it is all about duration AND rate. Flying long haul will expose a person to 3µSv to 6µSv /h. The highest rates were 6.6 µSv h-1 during a Paris to Tokyo flight and 9.7 µSv h-1 on the Concorde in 1996-1997. I would say shooting with this lens is safe as long as you're not storing it in a "Fanny Pack" for long periods of time or perhaps making a monocle out of it.
So not quite needing to make a lead-lined lens box :P
Considering humans made condoms containing Radium for humor, it's not surprising we have glass products with radioactive ingredients for genuine quality improvements. Though I'll bet there were health risks in the lens making process!!! Mixing ingredients... Grinding the glass...!
Dubious Conspiracy Warning: The lead in household paints was always known to be dangerous, but was phased out only after humans managed to reduce our emission of radioactive elements into the atmosphere. OR... it maybe we used it until made paint stick like sh** to a blanket :P
I figured the same thing Busters Garage, I bet the manufacturing process was potentially dodgy when they were making these lenses (but maybe they controlled the process well - can't say I've heard of any issues, unlike the people who applied the Radium paint on the watch dials). There were plenty of other things at that time that we now frown upon - as you said, lead based paints, and of course, asbestos - that miracle product you can still find in older houses, waiting for you to unwittingly drill/sand it and create dust to breathe in!!!
@@GrumpyTim I found my father's Spotmatic that was sitting in a case for about 20 years. A Takumar 50mm (7 element) was in the camera body all these years. Should i worry about the camera, or me using it? If i understand correctly, radiation doesn't get transferred from a radioactive object to a non-radioactive object, (unless the first breaks and radioactive particles actually move from one object to the other) so removing the lens and using the camera with a different one should be a completely radiation free activity, right?
@@waitwat1142 Spot on Birds are Dinosaurs, your father's Spotmatic will not be radioactive having had the Takumar lens attached for 20 years or so - rather handily the radiation doesn't migrate to another object like that. So if you want to use the camera with a different lens, you will be radiation free.
Of course you still have the radioactive lens sitting around somewhere - if you're concerned and want to get rid of it, they're a pretty popular item on ebay so you shouldn't have much trouble selling it, if that's what you decided to do.
I have the Super-Multi-Coated Takumar 55mm f/1.8 lens, which is radioactive too.
Can you tell me if it's safe to use the lens mounted to an SLR for some hours a day ? I just handle my camera with the lens every couple of days, and you said that about a foot away from it the radiation levels are almost indetectable.
If I just handled it like I said at this distance, is it safe ?
I accidently looked through the lens, about two inches away from my eye, for less than one minute. Could it have caused damage to my eyes ?
I never did this again, after I realized that it was radioactive.
Also, my camera is mounted with the lens, has a leather case on and it's sitting on a shelf when I'm not using it, in my bedroom, about 4 feet about my bed.
Should I store it somewhere else or is this distance long enough to be safe ?
Coo, that's a good lot of questions.
My understanding is, that the more radiation you are exposed to over a lifetime, the more risk you have of getting cancer as a result, BUT, before that makes you freak out, you can apply the same risk to almost everything you do - if you drive your car, every time you go out there is a risk that you could be involved in a fatal accident (albeit, hopefully a fairly tiny risk), so therefore, the more frequently you drive your car, the greater the overall risk is.
Normal background radiation where I live is around 0.15 to 0.3 Micro Sieverts Per Hour - which we'll refer to as uSv/h from now on.
We'll ignore the dose rate right at the back of the lens which was 13.84 uSv/h but if we look at the dose rate I measured at the back of the camera which was 1.15 uSv/h, that's only about 8 times the background radiation that your entire body is receiving all day, every day (and that's if I take the lowest background reading I quoted).
If you go on holiday and fly on a plane over the Atlantic, you're high in the earth's atmosphere and not getting the normal shielding from cosmic radiation that the atmosphere provides - up there you will be getting a radiation dose of 3.0 to 4.0 uSv/h (this is based on other people's information, I haven't measured this myself but it appears to be about right).
So, if you go on a 4 hour flight, your entire body will be subjected to the same dose of radiation that your face will be if you use your camera for 12 hours (maybe a little bit more for your hands on the focus ring, because the reading there was about 2.0 uSv/h).
In reality of course, if you're our photographing for a day, you only spend part of that day actually taking photos, the rest of the time your camera will be in your bag and therefore slightly further away from your body - and, as I said in the video, radiation levels fall off rapidly as the distance increases.
Put another way, if your local background radiation levels are 0.15 uSv/h then after 24 hours, your entire body has received a dose of 3.6 uSv - if you use your camera for a solid 4 hours pressed against your face, then your face will have received an additional 4.6 uSv dose - suddenly it doesn't sound quite so scary.
So, you should be fine to use your camera and lens, the additional risk is fairly minimal but, in my own opinion, don't unnecessarily increase your dose, ie by sleeping with your lens next to you in bed every night.
There will be no issue from you looking directly through the lens for a minute or two - I wouldn't want to make a habit of doing that all the time - I've heard of but never actually seen, old binoculars that had thoriated glass in the eyepiece - now that is a little more worrying because the radioactive source would be very close to your eyes, potentially for extended periods of time.
Theoretically, with your camera on a shelf 4 feet above your bed, it should be totally fine, BUT I always assume there's something I've missed or haven't been able to measure, so I would probably move it a little further away myself but that's only my own over cautious opinion and not based on actual science that I'm aware of.
Hope that sort of helps.
@@GrumpyTim Thanks for answering my questions !
I'm now less concerned, it's not as dangerous as I thought. I'm still going to keep my lens, but avoid handling it too much when not in use. I was very anxious when I got my film camera, I couldn't wait to take some pictures. That's why I was constantly picking it up and handling it. After I discovered the lens was radioactive, it made me a bit worried.
Hi Ryan, it's understandable to be concerned about having a radioactive lens, and depending on where you look you can find people telling you that it's the most dangerous thing in the world and everyone that uses one of these lenses is going to die (clearly untrue otherwise there would have been a large amount of photographers in the 60s and 70s that met an untimely end), OR other people telling you there's absolutely no risk at all.
I tried to make my video as unbiased and informative as I could whilst leaning towards the cautious side.
Enjoy using your film camera and Super Takumar lens - the old film cameras are lovely things - I've got lazy and very rarely put a film in any of mine these days, but just handling them brings a smile to my face.
I’ve carried such lenses with me constantly since 1967. And I only got cancer once. Non Hodgkins lymphoma in 2012. My mother has had it too. Possibly a family thing. Meanwhile, I simply don’t worry about this any more.
@@martyzielinski2469 I understand your point, but I prefer to avoid taking any risk, mainly because I'm young and don't wan't to have unwanted fear of something that should be part of my passion (film photography).
I moved my camera further from myself and don't plan in taking it of my shelf too often. Thanks for your reply.
Basically what you are saying here is that your lens radioactivity is not bananas
Yep, I think that just about sums it up!!!
so, are you saying that all "auto chinon" lenses are definitely radioactive-free, meaning totally safe? or just the 55?
is that a "yes, just the 55"?
Hi skepsys, I haven't heard of any Auto Chinon lenses being radioactive but I've only tested my own ones (I have about 5 of them), they were around at the time when it's possible that some models could have had Thorium added to the glass so I can't totally say that none of them will be radioactive.
The ones I've tested are my 55mm f1.4, 28mm f2.8, 200mm f3.5, 135mm f2.8 and a 55mm f1.7
@@GrumpyTim thanx
Hi, thanks :) Do you know if the Vivitar 28mm, super wide angle, F2.0 is radioactive? Thanks :)
Hi Cofake-1984, I haven't heard of the Vivitar 28mm f2.0 being radioactive, in fact Vivitar isn't one of the names that you hear all the time when people are discussing radioactive lenses - that's not to say that it isn't radioactive of course. I've only got one Vivitar lens myself, a 28mm f2.5 - that one isn't radioactive. Possibly the only way to be absolutely sure is to check it yourself using a Geiger counter - there is a list of radioactive lenses on the camerapedia fandom site but I don't think the list is necessarily complete, or even how accurate it is but at least it's a good starting point. Out of all my vintage lenses I actually only have the one that's radioactive - the Super Takumar 50mm f1.4 which is well known to be radioactive.
If you have a large collection of vintage lenses or you buy vintage lenses regularly, and you're interested or worried about radioactive lenses, a cheap Geiger counter from Amazon should give you a definite answer.
Sometimes the radioactive lenses take on a brownish yellow appearance in the glass, which can be an indicator that the lens is radioactive but it's not a reliable way of checking - not all radioactive lenses will be brownish yellow (particularly if someone has taken the time to de-yellow them), and not all lenses that look brownish yellow will be radioactive - there are other reasons such as the coatings used that can give a lens a yellowish appearance.
You could of course fit a lens to a digital camera and do a long exposure (say 2 minutes) with the lens cap on and then repeat the experiment using a modern lens - if the Vivitar showed significantly more noise in the image, then it could be an indication that it's radioactive. Make sure you shoot fully manual ISO, shutter speed etc and even noise reduction, otherwise the camera might add it's own confusion to the results.
Hope that sort of helps.
@@GrumpyTim Thanks for your extensive reply :) They talk about the Vivitar Series 1 28mm f1.9 as being radioactive; what I wanted to know is if the Vivitar 28mm, f2.0 MC auto wide angle is newer than the series 1, thus non radioactive, right? Do you know where I can get a cheap geiger counter? My lens is this one: www.pentaxforums.com/userreviews/vivitar-28mm-f2-mc-m-series.html
Your Vivitar looks like a really nice lens - as you say, the f1.9 version is listed as radioactive on the Camerapedia page, so it is possible but far from definite that the f2 version that you have is also radioactive - I would kind of suspect that you would come across some information online saying that it was radioactive IF it was actually radioactive - I've done a couple of searches and not really found anything useful about your particular lens.
The budget Geiger counter that people (including myself) use is the GQ GMC-300E available from Amazon - sorry for the long link www.amazon.co.uk/QG-GMC-300E-Plus-Radiation-dosimeter-monitoring/dp/B00IN8TJYY/ref=sr_1_5?crid=1HF8SXBK8WQAN&dchild=1&keywords=geiger+counter&qid=1615895023&sprefix=geiger+counter%2Caps%2C148&sr=8-5 There's a TH-camr "Geiger Fever who appears to do reviews of Geiger counters so he might be worth checking out too.
If you do find out a definite yes or no about your lens, I'd be interested to hear.
@@GrumpyTim thanks :) I also have the Canon 50mm FD F1.4, and the Minolta Md 28mm, f2.8. I think these ones are safe, right? :)
I've just had a quick look at the two lenses that you mentioned - if I'm looking at the right models, they look like they are probably new enough to have avoided the radioactive trend.
As far as I'm aware, you can have a lens that's radioactive, and then a later version of the same lens that isn't because it was produced after the time that the manufacturer stopped using Thoriated glass, so it's not always reliable to think that just because one lens IS radioactive, that all versions of that lens are - and vice versa of course.
As far as "safe" goes, it's kind of relative - the old radioactive lenses aren't that unsafe, but now we all know they're radioactive, it seems sensible to treat them with a little respect. Theoretically, occasional use of these lenses will present such a tiny addition to the amount of radiation your body will receive in it's lifetime that it isn't worth considering, BUT it makes sense to not increase that exposure unnecessarily by sleeping with the lens in your bed for years or carrying the lens in your pocket for absolutely no reason. Which of course loops back to you wanting to know if your particular lenses are radioactive - my hunch is that your lenses aren't radioactive, but the only way I'd know for sure would be to test them with a Geiger counter.
Sorry for not giving you a definite answer - if I suddenly find out, I'll let you know.
Is the canon fd 50 f/1.8 radioactive as well?
Hi niu-Finn, I haven't tested the Canon FD 50mm f1.8, or any other Canon lenses for that matter, but, from what I can tell, the FD mount lenses were introduced at a time when most of the radioactive lenses had been phased out. Obviously this is not a definite answer, but my hunch would be, that your 50mm f1.8 is not radioactive.
Hope that helps.
@@GrumpyTim Many thanks :)
@@GrumpyTim sorry to bother you again.
I saw a video, where the guy said that lenses also emit gamma rays, is that true?
Another question of mine is: can this radiation "transfer" to other objects, e.g if I store my ipad with the lens in my backpack, is my iPad radioactive as well? If yes, how long?
Hi niu-Finn, I deliberately kept the physics lesson simple in the video because it's such a complex subject that I could have done a whole series about radioactive decay and still only just touched the surface of the subject. I listed the main decay chain which is made up of Alpha and Beta decay, but there can apparently be some Gamma rays emitted too - there's a little bit of information in this link (athough I haven't checked the accuracy of the information here) pubs.usgs.gov/of/2004/1050/thorium.htm.
From what I can make out, the amount and strength of Gamma emitted will be relatively low - Gamma Rays can travel further and penetrate more than the Alpha and Beta particles but if there was a significant amount of Gamma reaching further from the lens, then there should have been some evidence even on my basic Geiger counter.
Additionally, there is a phenomenon called "Braking Radiation" or "Bremsstrahlung" given it's German name, where high energy beta particles can hit the lead with such force that the lead decays and emits gamma radiation. I've initially heard about this regarding the making of storage containers for high beta emitters such as P32 - I do not know if it applies to these lenses, but I'll just assume that it does for now. In the case of making a box to store your high beta emitter, the beta emitter should first be surrounded in something else and then the lead on the OUTSIDE of the box. I believe Perspex is sometimes used as the inner layer with the lead on the outside but I haven't yet done enough research to confidently recommend an exact method of construction for a radiation proof container. Now, my theory here is, we know from the decay chain that when a Thorium atom gets to the end of the decay chain, it finished in the stable form of Lead, and although the half life of Thorium is 14 billion years or so, that only means that it will take 14 billion years for half of the original Thorium to decay. The actual point in time that any one single atom will decay is totally unpredictable, therefore, it's not unreasonable to assume that some atoms have already reached their stable form of Lead, and therefore, IF the Braking Radiation phenomenon DOES apply to these lenses, it seems possible that a Beta particle from the lens could hit one of the Lead atoms, causing it to decay. This is beyond my knowledge area so I'm only expressing my thoughts rather than exact knowledge here.
On your final question, "can the radiation transfer to other things" - that would be no. The particles emitted by the lens will hit, and some will pass through, other objects depending on what the objects are, but that object won't magically become radioactive itself.
Hope this helps.
@@GrumpyTim Many thanks again!
I have a Super Takumar 135 mm that I belive isn't radioactive: it also doesn't get yellow.
Hi Badscrew, I haven't had a Super 135mm Takumar in my hands to test, but I haven't seen anything to say that model was radioactive. Definitely the fact that a manufacturer made some radioactive lenses, doesn't mean that all of their lenses were radioactive - they would only have used Thoriated glass if there was an increase in optical performance to be had in a particular lens.
I also own a SMC Tak 135 f3.5, this is by far the most common 135 so I am assuming it is also the same one you have. I've not seen any article that showed thoriated glass ever being used in a 135 3.5.
I own both the 135 3.5 and the 135 2.5 more rare version, and I am testing both tomorrow. Neither show up on any of the testing lists, as most of the thorium glass was made in 50mm lenses thereabouts.
Incredible video! In my opinion, there's no reason at all, in 2020, to buy a radioactive lens... A modern CHEAP! 50mm lens has AF, is much more sharp, flexible and safe, than this in the video.
I can't argue with your thinking although there is a certain fascination in using vintage lenses of all kinds. I wanted the Super Takumar, not because it was radioactive but because I'd heard so many reports of how good it is, and in terms of vintage lenses it IS pretty good - I haven't tried a back to back comparison with a modern 50mm - maybe that's something for a future video.
For most of my still photography and particularly architecture and landscapes I definitely favour modern lenses on my full frame Nikon but I actually love the look I get from the vintage lenses on my Panasonic camera when I'm shooting video - its the imperfections that add a little interest.
I'll keep collecting and fixing vintage lenses but I have no particular desire to get more radioactive models - it was interesting playing with the Super Takumar and doing all the research for the video - if nothing else, it forced me to learn a whole load of new stuff, so that can't be bad.
Bizarrely, the thing I miss most when using vintage lenses isn't the lack of autofocus, but it's not having the aperture in the meta data. If I'm taking shots specifically to use in a video I'll make a note of what aperture I'm using but otherwise, I generally can't remember what aperture I shot at, if I look at the image a couple of weeks later!!!!
Have you got any top tips for a cheap modern 50mm - I might look one out and give it a try.
Cheers for the comment.
@@GrumpyTim My opinion on 50mm lenses is not the "most documented" because I do not use anymore 50mm lenses (I find them "too wide" for portrait or macro photography, and "too tele" for landscape, travel & family photography).
However, I think that the Nikon 50mm 1.8 AF lens (which costs around 200€) is an excellent VFM choice! I've used this lens in the past on a D750 body, and I noticed how reliable it was!
Anyway, I can't criticize at all anyone's options for vintage lenses! Creativity and pleasure are expressed in different ways for anybody! But they must not harm our health...
@@k.7306 I'm much like you in that I hadn't used 50mm lenses for years - on full frame they're not wide enough for landscape and not really long enough for portraits, but on the Micro Four Thirds with it's 2x crop factor they make quite a nice short tele with an equivalent focal length of 100mm (or 110mm if it's a 55mm lens). That same crop factor can be a bit annoying if you want to shoot wide though and I think my full frame Nikon will remain my preferred choice for landscapes.
Have a great Christmas :-)
@@GrumpyTim Exactly! However, a 50mm lens doesn't be transformed into a 100mm lens on a Micro 4/3rds sensor (or into a 75mm on a crop sensor) - it simply "offers" the same angle of view. If you want to capture a whole-body portrait (for instance), with a full frame camera & a 105mm lens, you have to be 5m away from the model. For the same whole body portrait with a Micro 4/3rd camera & a 50mm lens, the demanded distance between the camera & the model is closer to the lens' infinity focus distance, and the background blur is not the same as this one in the fx set up. Everything seems to be dealing with maths...
Merry Christmas! Stay Safe @home!
Cheers, yes, maybe I should change the way I describe the crop factor effect when using Micro 4/3 cameras - I know it doesn't suddenly change a 50mm into a 100mm but for many people it's the simplest way to describe the effect without getting too technical. Probably a better way for me to explain (not to you, as you clearly understand focal lengths fully), would be to say using a 50mm lens on Micro 4/3 is like shooting on a full frame camera and then cropping to image to 50%.
I've spent lots of time in the past explaining to people why parts of their shot will be cropped off if they want it put in a 10" x 8" frame (or any other non original aspect ratio).
Hope you're having a good Christmas period with plenty of good food.
I've got a Pentax Takumar showing 7.73uSv/hr when the GMC-320 is placed on the rear.. how much gamma here
Hi David, I'd need to do some more precise and controlled testing to estimate how much of that was gamma - maybe something like enclosing the lens in 12mm of aluminium (a bit of silver foil isn't enough) would be enough to cut out nearly all the alpha and beta, and therefore what was left would be gamma, but I'd want to do some tests with known quantities to see if my theories were right before believing the results.
@@GrumpyTim I read some mm of aluminum will help stop most beta, but then my other lens is an Asahi Tele Takumar 300, an inner element I read has the Th, it still reports several hundred CPM, gamma indeed. I need a better GC.
Hi David, from the little bit of testing I've done, plus the little bit of knowledge I have, you need quite a thickness of material to completely stop the beta let alone the gamma. It would always be interesting, purely out of scientific interest, to try to identify how much of each type of radiation was being emitted. I made a box to contain my Takumar, along with a few other radioactive items - it has something like 1.5mm of aluminium, 10mm of dense wood, about 3.5mm of lead and then finally 6mm of plywood - all it does is reduce the amount of radiation, it doesn't block it completely at all. Which doesn't matter, it was again out of scientific curiosity to see if I could make a simple enclosure that would completely block the radiation, the answer being NO!!!
@@GrumpyTim It's my understanding that if you use a relatively high-density material like aluminium to absorb alpha and beta particles/radiation, their rapid deceleration will cause gamma rays to be produced. That's actually where the gamma rays are produced, because the whole 11-step decay chain from Thorium-232 to Lead-208 is by alpha and beta decay only.
Hi Chris, I'd done a little delving into "Bremsstrahlung" or "Braking Radiation" and I knew the phenomenon could occur when high energy Beta particles struck lead without something between to slow them down - I had been talking to someone who regularly handled P32, which is stored in a perspex (or similar) container, which was then surrounded by a slug of lead. I didn't delve much more than that. If the phenomenon can occur with aluminium as well, then it will happen as the Beta particles strike the aluminium lens housing anyway. I did initially plan to use perspex as the inner layer of my storage box, but for some reason I changed my mind before I made it. I did get some information from another viewer which I'll paste below when I find it.....
Found it.....
"Hello again, what is happening is that the two naturally occurring isotopes of thorium decay at different rates, leading to the ‘growing in’ of two different isotopes of radium, which emit gamma rays. The main problem is the (tiny) minority isotope Thorium-230, which leads to in growth of radium-226 which emits 186keV gamma radiation, as well as alpha particles, and has a half life of 1600 years. If we make the reasonable assumption that all the thorium decay products are volatilised in the glass melt, then the newly made lens has negligible radioactivity. From that point, thorium decay product isotopes with shorter half lives (ie more radioactive disintegrations per second) start to appear and continue to build up until a radioactive ‘equilibrium’ condition is reached, after perhaps a few hundred years (I haven’t calculated it yet)... A Super Takumar 50mm f1.4 lens would have had about zero Becquerels(Bq, SI unit of radioactive decay = 1 disintegration per second) of radium-226 when new, but my example made c. 1967 now has about 40000Bq of radium-226 and this will roughly double over the next 50 years. I have two examples of the f1.8 version and the radium-226 content is roughly half, (i.e. about 20000Bq) which is what one might expect as the lens element has roughly half the area of the f1.4 version (almost 1 f stop). For a given example of the lens, the radioactivity is only a function of the time since manufacture. Concerning the coating, it’s quite possible that thorium elements were coated with thorium compounds in order to achieve suitable refractive indices. The coatings are quite hard and can only be removed by quite aggressive cleaning processes. However, avoid chipping the glass because if one were to cut oneself on a glass splinter, that could give rise to a significant internal radiation dose. On the Takumar lenses, the thorium element(s) are usually in the internal group between the iris diaphragm and the rear element and hence not accessible without dismantling the lens. A scratch on the rear lens element presents no radioactive risk."
If you are worried by that chart, which clearly is a "we have no idea so we will just cover our backsides", then you will never fly in a plane again.
If you however see that chart for what it is, and see that its > 13uSv/h advice is just cold war "duck and cover" BS then continue flying happily at over 40uSv/h :)
And again if you are concerned, never go to California, the whole placed is hot, its in the damn soil you walk on all day and taking a walk on a beach there should look like Fallout 3, yet it strangely doesnt. Also never go to that highly radioactive beach in Brazil where people who live long keep burying themselves in the highly radioactive sand as it seems to "keep them going". Its probably the bananas to be honest, the sand is just a radioactive gimmick.
Basically, the only think you need to do is dont eat lenses.
Hi dlarge6502, I featured the chart only because it was in the box, rather than because I wanted to show "how dangerous these lenses are!!!!!" - I was trying to present a relatively balanced video and not try to dramatically scare people.
As you say, there are many places in the world where the background radiation is significantly higher than it is where I live for example, and the people there don't grow two heads and zap their enemies with their x-ray vision! I seem to recall that the radiation levels in Cornwall are higher than much of the UK but it doesn't mean you shouldn't go there.
I would still advise (rightly or wrongly) not to cuddle up to one of these lenses every night in bed - the risks are probably still minimal but it would unnecessarily add to your lifetime accumulative dose of radiation. Simply leaving the lens a few feet away or in another room would do the trick.
Cheers for the comment.
@@GrumpyTim I meant "you" as in the viewer ;)
I think the levels listed on the chart are wildly conservative and even presented (on the chart) in a way that helps induce irrational fear of low level radiation, which we simply don't know anything about. I think that chart is subdivided on the CPM, not dosage, looks like they just listed 100,200...,1000,2000 CPM and then converted to a dosage unit. It should have been the other way around imho. High radiation levels we know well what happens medically there but we have relied on assumptions about how any organism that evolved on this planet, in all sorts of radiation levels, will deal with such low amounts.
Your video was pretty clear in not being one sided. Unlike the Chernobyl "docu drama" which intentionally over dramatised certain things just for, drama, such as the helicopter flying over the reactor crashing "due to radiation corroding the metal" instead of what really happened which was the chopper, a few days after the main event, hit a crane cable that the pilot could not see due to the smoke and steam from the reactor.
We need to re-evaluate our entire understanding of low levels of radiation to help us shout down the "manic" theories from the various groups who have hampered the development of nuclear power for the last several decades. They think Chernobyl was a result of the fact it was a reactor, and not the result of a rushed design built to a very low cost (it had no pressure vessel, nobody else builds reactors like that) simply to allow the Russians to enrich uranium.
Back on subject. I found that there are a ton of lenses from many manufacturers which emit levels of radiation. They seem pretty common. I don't care about the radiation from them, I'm more interested in the cameras that used glass treated in the same way for the viewfinder. I don't think these were common, however. It would be interesting to test them. There you would be frequently very close to the radiation source, well your viewing eye that is.
Radiation from the main lenses could also fog film, which would be an interesting test much like you did with the sensor on your camera. If you want to see a video of that, look up Thunderfoot on TH-cam. We works with reactors often and placed his iPhone in beam of radiation while it was recording video :D
As for sleeping with the lenses. I would avoid that, it makes the lenses dusty! If you were to strap the lens to me and have me keep it in the same spot for a year I would probably have something to say about that!
Ahha, silly me, yes "you" was not intended as me personally :-)
I haven't seen the Chernobyl docu drama but I can believe that it would be over dramatised - the helicopter bit sounds ridiculous, people will take that as fact - radiation makes aircraft crash.
I think the general mis-information about radioactive stuff is now so ingrained in many/most people's minds that it will always be the big bad monster and must be avoided........until you're ill and need an X-ray. I wonder if people would stop going to concerts that have a LASER show if they know what the "R" in laser stands for. I guess in general it's not a bad idea if people are cautious rather than complacent.
I'd heard about some binoculars that had thoriated glass in the eye pieces - I haven't actually seen any myself so that's just on other peoples word but that is a bit of a scary idea and I'll definitely be testing any stuff like that if I see it on my travels.
I'll look up Thunderfoot, that sounds interesting. I kind of figured that most of the radioactive lenses were the higher end lenses and therefore would have been used by professionals or keen amateurs so probably they didn't leave film in the camera very long without taking a photo and moving that frame away from the strongest concentration of radiation.
@@dlarge6502 Cheers for the tip to watch Thunderfoot - I just watched his video on growing plants in radioactive waste, that's a VERY good video - even though I know it's ok, it still made me giggle like a school kid seeing him eat his dinner off the Fiesta ware.
Hello. Here we go again...You say your device does not measure alpha rays, but putting paper in between makes a lot of difference (therefore your device is actually measuring alpha rays, but the lens is supposedly with thorium and not tantalium). You say that putting aluminium foil also has an effect on the reading but that would eliminate only the beta rays. To stop gamma, only lead or thick concrete walls: what are you measuring exactly?
Hi Patrizio, thanks for the comment. The manufacturer of my geiger counter states that my counter isn't sensitive to alpha radiation and I'm happy to believe them about that.
The book I used was 12mm thick so the increased distance would significantly reduce the amount of beta radiation because beta drops off rapidly as the distance increases. Also, the paper and ink within that book has a certain amount of conductivity and with that density of paper and ink it will also reduce the beta radiation to a certain extent. The point of that part of the exercise was just to disprove the myth that these lenses only emit alpha radiation.
The aluminium foil did reduce the level a little as I expected - what I was trying to prove at that time was that wrapping a lens in aluminium foil will block the beta radiation is a myth, you'd need about 20mm thick aluminium to block the beta radiation entirely, so a tiny bit of thin aluminium foil will only block some of the radiation.
Looking at the decay chain of Thorium the radiation will be entirely alpha and beta radiation that is emitted.
Hope that answers your questions.
@@GrumpyTim Hi. The half life of Thorium is 14 billion years - I think you'll have to wait a little bit longer to see some "important" difference...Science for kids (source Britannica): kids.britannica.com/students/assembly/view/53873 and from US NRC www.nrc.gov/about-nrc/radiation/health-effects/radiation-basics.html#:~:text=Alpha%20Particles,-Alpha%20particles%20are&text=In%20other%20words%2C%20these%20particles,does%20not%20pose%20a%20danger.
Hi Patrizio
I'm interested, are you a fan of these old radioactive lenses or do you dislike them?
I did as much research as I could before making this video to make sure my facts were mostly accurate - I wanted to give balanced and factual information without delving too deeply into the physics of the subject.
Regarding the half life of Thorium, you are absolutely correct that the half life is 14 billion years - which means that after 14 billion years, half of the Thorium will have gone, or at least it will no longer be Thorium. The term "half life" refers to the rate of decay of the Thorium (or any other radioactive material), it doesn't mean that you have to wait for 14 billion years for anything to happen.
This decay happens at an atomic level and it is totally random and unpredictable at what point in time a single atom will decay. The decay will be a continuous process and when an atom of Thorium decays (ie it emits an Alpha particle), it then becomes Radium. That Radium atom then has a half life of just 5.7 years - so within 5.7 years it has a 50/50 chance of decaying itself. When that Radium atom decays it will emit a Beta particle (which my geiger counter IS sensitive to). Once that Radium atom has emitted it's Beta particle, it becomes Actinium. The Actinium atom has a very short half life of 6.1 minutes and when it decays it also emits a Beta particle, and so on all the way down the decay chain.
Admittedly, the majority of the radiation emitted by the Thorium and it's daughter isotopes will be Alpha particles but, as shown in my tests, there are plenty of Beta particles too. If I was able to measure Alpha particles I would expect to see much higher levels of radioactivity.
Hope this helps.
@@GrumpyTim Hi Tim. For sure the thoriated glass gave a distinct advantage to those companies who used it.
I have a few of those radioactive lenses, mainly Takumars. Some of those are supposed to be radioactive and actually are radioactive and some that are supposed to be radioactive but actually aren't (I cannot explain this mistery, but the serial numbers position them close to the time when Asahi decided to stop using radioactive glass and my RADEX RD1212-BT seems to be operating ok).
If Thorium dioxide was used up to 17% w/w to produce glass (no idea about the production process, since molten glass is produced at about 1500 °C but Thorium oxide melts at about 3200 °C), some lenses were coated using thorium flouride. You are right about the decay process, but I invite you to consult these pages: pubs.usgs.gov/of/2004/1050/PalosVerdesRn.htm#thorium.htm
hps.org/publicinformation/ate/q11530.html
where you can see that some of the daughter isotopes do emit gamma rays as well.
If you are worried about the effects of radiation exposure to lenses, again I suggest to refer to this official army document: assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/383654/JSP392_Lft_29_Thorium.pdf .
Dose rates fall off with the distance, as you noticed, therefore the occasional use of lenses with thoriated glass should not really create a health problem. Since flaking is possible, those lenses wich were coated with throrium flouride have a higher risk of inhaling radioactive particles
In accordance to the suggestions in the army document, I store my lenses in an aluminium case where I removed the foam and glued all around walls of lead sheets 1,5mm thick, then placed the foam back again. Next step will be to place a radioactive material sticker outside!
I hope I was able to add some useful material to your research.
Take care.
@@patriziodalessandro1693 Cheers Patrizio, I think I read the army document a while back (in fact I've got it bookmarked in my browser) - quite an interesting read.
It's a fascinating subject and kind of a shame that there wasn't an equally good replacement for the Thorium in the lenses when they stopped using it.
Similarly, I store my lens well away from me and my other equipment. I'm still happy that they are ok to use for their intended purpose, as a camera lens but definitely people should be aware that there are certain risks, most significantly if you happened to inhale some broken fragments or flaking coating as you suggest - that is quite a scary thought.
I love the sound of your lens storage box - I might copy your idea.
I'll have a look at some of the other documents you shared links to later.
Cheers for some useful information.
Have a great day.
Anything bad to health ?
Hi Anuraj, with these lenses we're talking about relatively low levels of radiation, and generally with low levels of radiation it's all about how much radiation you receive over a lifetime - there's radiation everywhere anyway, coming from the planet that we live on and from the sky. Being in close contact to one of these lenses will marginally increase your lifetime exposure to radiation so with that it will bring a tiny tiny amount of increased risk - if you're using the lens occasionally it's fairly reasonable to assume that the increased risk is so small that it's not worth worrying about. If you were using one of these lenses all day, every day, your increased dose of radiation would still be fairly low, and in many peoples opinions, still not worth worrying about but it might be sensible to not use one of these lenses as your every day lens. It would seem a sensible precaution not to store the lens close to where you spend a lot of time such as under your pillow.
Hope that helps a little bit.
@@GrumpyTim Thank you for the information! I have my lens collection (I'd say 1 third of them are radioactive) in an office cabinet under my desk, on which I spend at least 8 hours, daily. I'll definitely put them a little farther.
@@marvinracer88 Hi Mark, it may well be that your lenses are fine exactly where they are, but for the sake of your own peace of mind, I would do as you suggest and move them a little further away. I've got a Mamiya Sekor lens on my workbench at the moment - I didn't know it was radioactive until I received it and the geiger counter started clicking wildly - it's a bit of a wreck of a lens (mechanically not optically) but it'll be fun to try it out once I can actually focus the thing.
@@GrumpyTim Thank you for the quick response! Just found your channel yesterday, already subscribed. Thank you for being so thorough.
@@marvinracer88 Thanks so much Mark, that's really kind.
Of the Super Takumars, is it only the 50mm that’s radioactive or the entire set and every focal range lens?
Hi SurgeNetwork, there were several of the Super Takumar lenses at that time that were radioactive but not everything that they made. The same applies to other manufacturers such as Canon, Zeiss, Olympus and Yashinon (among others) - all of these produced some radioactive lenses in that period. Generally it was the better quality lenses that were radioactive rather than the cheap and cheerful ones. Out of all my vintage lenses, only the Super Takumar that I featured in this video is actually radioactive - I thought my Yashinon was going to be but when I tested it, there was no radiation.
@@GrumpyTim Do you know if the vintage Olympus OM Systems lenses are amongst the radio I strive? And the Vintage Zeiss Contax?
Hi SurgeNetwork, There's a list of radioactive lenses on camerapedia - if you search for "camerapedia radioactive lenses" it should pop up in your search. I have no idea how accurate or up to date the list is but it's useful as a starting point anyway.
From what I can tell, the majority of radioactive lenses had been phased out by the 80s so theoretically, the later in the 70s a lens was made, the less likely it is to contain radioactive glass.
Two of my OM lenses are hot. The 55mm f1.2 is the hottest of my collection, so far.
Olympus OM-System G.Zuiko Auto-S 55mm f1.2 1974 Radioactive 3389 CPM
Olympus OM-System Zuiko MC Auto-S 50mm f1.4 Black Nose Radioactive 460 CPM (Great Color Rendering)
Auto Mamiya Sekor 55mm f1.4 with M42 Mount TOMIOKA Design Radioactive 460 CPM
Asahi Super-Multi-Coated Takumar 55mm f1.8 Radioactive 750 CPM
Asahi Super-Multi-Coated Takumar 35mm f2 Radioactive 1850 CPM
Asahi Super Takumar 50mm f1.4 Radioactive 2250 CPM SN 3237402
some are, some are not. Google "camerapedia radioactive lenses"
The 8 element Takumar isnt radioactive.
Hi Nick, I'd read that some of the 8 element versions were non radioactive and some were slightly radioactive, but nowhere near as radioactive as my later 7 element model. I have no idea how accurate that information is, and short of someone giving me a sample of maybe 3 of the 8 element version from the beginning, middle and end of production (which would be nice but somewhat unlikely), I have no way of finding out for myself. Do you have one of the 8 element models, and do you know if it's an early or late one? It would be kind of nice to get hold of a load of the radioactive lenses from all manufacturers and measure the radioactivity using some better equipment and a more controlled test set up, to create a really accurate database, but that would be a rather expensive exercise, not to mention that I'd then have a huge lens box full of radioactive material!!!
Grt video, thx. I have the 8 element version. Gonna test it now!
I have 6 different 50mm f1.4 Takumars including an 8 element. My 8 elemtent does not have a yellow cast and i have not had to de-yellow it like my other examples. I also have some 55mm F1.8 Super Multi Coated Takumars that have thorium in the glass.
Close Proximity is a tautology and Bad English. Proximity to the lens is correct, close proximity means close near.
Hi Mark, I'll take it as a positive that your only criticism was a bit of bad English and not bad particle physics. I'm sure bad English is one of my specialist subjects and you'll more than likely find examples in all of my videos (no I'm not suggesting you go searching for them). You are correct, but I think people will get what I was meaning.
A tautology! By Jove old chap, where may I ask did you learn English? Well done. Just remove the capitalisation in "Proximity" and "Bad", then substitute "poor" for "bad", and you'll be well on your way to a medal from the King, fine carriages, country estates and as many girls as your tongue can cope with😜
Ive never heard someone say Beta that way until now...
Ah yes, a lot of people pronounce is a "Bayter" whereas I say "Beeter" - I've not really considered which might be correct, or maybe they're interchangeable. I guess I grew up hearing about the Lancia Beta and it's infamous rust problems and everyone called that a Lancia "Beeter" so I just followed suit!!!
While it’s true that pure thorium decays by emitting an alpha particle as stated above, this is only the start of the long series of decays that emit alpha, beta and gamma radiation until it ends with the stable isotope of lead. You can read it as such:
Thorium 232 -> releases alpha α -> becomes Radium 228, then
Radium 228 -> releases beta β- -> becomes Actinium 228, and so on.
radium, actinium, radon, polonium, bismuth, thallium, and lead in minute quantities, resulting from slow thorium decay.
I plan on using Plexiglass to stop the alpha in it's tracks. 1 inch of Plexiglass should know it down a lot. 2 inches should block it completely.
Jim
This guy loves to hear his owm voice.
I had Multi Grain Hoops for breakfast.
Unsurprisingly, his voice conveyed more of interest and relevance than your asinine, adolescent comment.
And for a good reason!