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Radioactive Legacy Lens
- Thread starter Ron766
- Start date
LOLI have some legacy lenses. Should I be worried about the radioactive lens?
Are these some sort of dangerous? I always imagined "the hulk"!
Which lenses do you have? Only certain legacy lenses have radioactive elements, generally using Thorium or Lanthanum glass.
Even if you have one or more lenses that have 'radioactive' glass, the risks to your health are tiny - unless you plan on grinding up the glass and inhaling or ingesting the dust, there isn't really any cause for concern.
Some old cameras used radioactive glass in their viewfinders which is far more dangerous due to the close proximity of the users eyes to the glass for extended periods of time. No need to worry with any modern camera though!
davect01
Veteran Member
Yup, it is mostly in the glass.LOLI have some legacy lenses. Should I be worried about the radioactive lens?
Are these some sort of dangerous? I always imagined "the hulk"!
Which lenses do you have? Only certain legacy lenses have radioactive elements, generally using Thorium or Lanthanum glass.
Even if you have one or more lenses that have 'radioactive' glass, the risks to your health are tiny - unless you plan on grinding up the glass and inhaling or ingesting the dust, there isn't really any cause for concern.
Some old cameras used radioactive glass in their viewfinders which is far more dangerous due to the close proximity of the users eyes to the glass for extended periods of time. No need to worry with any modern camera though!
Here is some info to read:
http://camerapedia.wikia.com/wiki/Radioactive_lenses
"Most smaller lenses with thorium elements are not very dangerous. However, thorium eyepieces are dangerous. They can give a very large alpha and beta particle dose to the cornea of the eye, causing cataracts and other problems. Normally these particles are stopped by , but the surface of the eye is quickly damaged by them, and at close range, the dose can be very high."
"By far the most prolific producer of radioactive lenses was Eastman Kodak. From the 1940s through the 1960s, substantial numbers of amateur cameras were produced and sold with thoriated (containing thorium oxide) lenses, including some of the Pony, Signet, and high end Instamatic (e.g. 800 and 814, but not 100 or 124) cameras. In addition, many professional level Ektar lenses from this era contain thorium. Perhaps the most famous radioactive lenses of all were the Kodak Aero-Ektars."
--
Novice . Former NEX-3, F3, and 6 . Current proud A6000 owner.
http://davesnex-3photos.blogspot.com/
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ProfHankD
Veteran Member
Of course you should... in the same way you worry about putting on a safety belt when you get into your car even though the probability of needing it that trip is quite low.
It turns out that adding heavy rare earth elements to glass does good things for the optical properties. You knew this: remember how people are always praising the appearance of lead crystal? As much as 15% or 20% of a "glass" element could actually be one of these rare earth additives. Unfortunately, these rare earths include many radioactive isotopes, and they might also be significantly contaminated with other elements from the relevant decay chain -- so, the radiation source is really integral to the glass. By the late 1970s these radioactive materials were phased out of use; modern lenses tend to use cheap aspheric elements to get many of the same kinds of design benefits (although cheap aspherics have optical issues, such as the "onion skin" bokeh problem).
Most of the radioactive lenses (exceptions include some military lenses) primarily are low energy emitters where most of the radiation is stopped by the lens barrel or camera body before it can reach you. Don't grind-up and eat or inhale your radioactive lens, and the exposure risk is quite low. However, the decay chains for elements like Thorium have a variety of emitters, so you might see a mix of alpha, beta, and gamma. The higher-energy gammas don't get blocked so easily, so they're the primary concern, and even Thorium itself emits some gamma. Overall, many radioactive lenses produce significantly above normal background radiation levels when in close proximity, so don't keep them too close all the time -- remember that inverse square law stuff? Radiation risks from using most radioactive lenses are vaguely comparable to flying a lot on commercial jets, where the higher altitude multiplies your exposure, and are far lower than eating off red fiestaware.
One of my radioactive lenses; the yellow patch shows the severity of radioactive yellowing
The radioactivity will often cause yellowing of the glass. Most radioactive lenses have just one radioactive element, usually at the back, although some are at the front and the Minolta Rokkor 28mm f/2.5 has it in the middle. It is chemical changes that cause yellowing, much like white plastic parts yellow with exposure to sunlight -- interestingly enough, the "cure" for radioactive yellowing is UV light exposure. It may take from hours to weeks of exposing the lens to UV to remove most yellowing, mostly depending on how much UV light gets to the yellowed glass; glass blocks most UV, so the element in the middle of the aforementioned Rokkor takes a lot longer to clear than the one at the rear of a Takumar 50mm f/1.4. I have observed that the yellow tint does more damage than just tinting the image, so I strongly recommend UV treatment of any yellowed lens. Of course, UV treatment doesn't make the lens stop being radioactive, it just bleaches the yellowed materials.
nuzzart
Forum Enthusiast
I have the Minolta Rokkor 28mm f/2.5 lens. What is the best way to clear it?
Since the element is in the middle, is it better apply the UV from the front of the lens or from the mount end, or maybe from both ends?
What can be used as the UV source? Does a full spectrum CFL bulbs provide any UV or do you need a specific UV bulb?
Thanks for any information.
ProfHankD
Veteran Member
Be very patient. ;-) Mine took a month or so.
Kind of a losing battle either way.
Nobody has posted a definitive answer. It's complex because there are so many UV emission profiles (UV is a band with highly frequency-dependent absorption characteristics) and lots of UV is absorbed by lens glass. I've tried everything from ordinary daylight to UV EPROM erasers. Overall, halogen lamps with aluminum foil shaped around the lens to direct the light in seem to be one of the better choices, but keep in mind that you don't want the lens to get too hot. A halogen lamp fixed yellowing on the Tak shown in about a day or two, and on another in just a couple of hours... this stuff really varies a lot.
Sorry about the bad news that it's slow to fix. The good news is that the 28mm f/2.5 is one of the best performing 28mm ever made -- when not yellowed. It's barely average when seriously yellowed, and hence often undervalued. A true "sleeper" value wise....
PC Wheeler
Forum Pro
How did you clear yours? I have one of these, too.
SQLGuy
Forum Pro
Maybe the Zuiko 1.4. I don't think any of the others are likely to be radioactive. It's pretty much only F1.4 or faster lenses.
ProfHankD
Veteran Member
Not exactly; there are various f/1.8 or slower radioactive lenses. It is often lenses that are fast for their focal length because the use of radioactive glass can simplify the design and, even more dramatically, can reduce weight and size. Basically, it allows for better correction with a smaller, simpler, optical formula. Contrary to popular belief, radioactivity doesn't directly improve bokeh, nor is the radioactive yellowing intended to be a feature to increase contrast (like yellow filters).
Known radioactive lenses include Kodak Ektar 101mm f/4.5 (large format lens, circa 1946), various Kodak Aero-Ektars, and at least some Takumar 55mm f/1.8. There are lots of lists online. In some cases, the lens was produced in both radioactive and non-radioactive variants.
nuzzart
Forum Enthusiast
Thanks for the information. I tried clearing the lens once before using a full spectrum CFL. I might have let it run only 4 or 5 days. Maybe I'll try again following your suggestions.
Thanks again!
Thanks again!
Dr JLW
Senior Member
ProfhankD covered most of the issue very well.
Most fast lenses of the 50's had these elements. All the major makers used the material.
There is one minor issue which is more a curiousity than a problem or a hazard.
These lenses can fog film. I saw an article in Shutterbug in which one of the lenses was paled in a Polaroid film pack for a few days resulting in and exposed spot.
At least one camera of the era, the Voightlander Prominent, was designed around the original 50mm f/1.5 Nokton which was "hot". The camera had two sets of metal shutter blades, I suspect the second set was to prevent film fogging from radiation from this lens.
I suspect that one of these lenses if mounted to a modern digital camera might produce a hazy background from a very long (hours) time exposure. Probably not for most cameras since the IR blocking filter would likely take out the radiation but in infrared converted cameras it might be possible.
To see the effect, which gives an idea of how likely it is to become a problem one needs a camera that can mount the lens remove the IR filter from its sensor and open the shutter with a cap on the lens and leave it for a an hour or so. Now when the shutter closes cover the camera or keep it dark and remove the lens while the camera corrects for sensor dark signal.
That is what you have to do to see the effect of this radioactivity.
Most fast lenses of the 50's had these elements. All the major makers used the material.
There is one minor issue which is more a curiousity than a problem or a hazard.
These lenses can fog film. I saw an article in Shutterbug in which one of the lenses was paled in a Polaroid film pack for a few days resulting in and exposed spot.
At least one camera of the era, the Voightlander Prominent, was designed around the original 50mm f/1.5 Nokton which was "hot". The camera had two sets of metal shutter blades, I suspect the second set was to prevent film fogging from radiation from this lens.
I suspect that one of these lenses if mounted to a modern digital camera might produce a hazy background from a very long (hours) time exposure. Probably not for most cameras since the IR blocking filter would likely take out the radiation but in infrared converted cameras it might be possible.
To see the effect, which gives an idea of how likely it is to become a problem one needs a camera that can mount the lens remove the IR filter from its sensor and open the shutter with a cap on the lens and leave it for a an hour or so. Now when the shutter closes cover the camera or keep it dark and remove the lens while the camera corrects for sensor dark signal.
That is what you have to do to see the effect of this radioactivity.
Forget danger from radioactive lenses. The gamma dose you get from them is insignificant. If you are a person who frequents a house basement a lot, or have a forced-air heating system, you are going to be exposed to a much more dangerous radioactive alpha particle source, dust particles that pick-up the daughter radioactive particles of radon gas which comes from the ground around the house, even the cement the foundation is made of. This dust then enters the lungs. About 20,000 people in the U.S. die every year from lung cancer caused by this. So, from an environmental standpoint, the mild radioactivity in lenses is harmless. I did know one person who was using an old Kodak Ektaprint (like an Ektar) lens as a telescope eyepiece, that is best avoided since gamma radioactivity exposure is subject to the inverse square law where the closer you get to it, the bigger the dose and the longer you stay in proximity, the bigger the dose.
Focus Breather
Senior Member
These are dangerous lenses. I will safely dispose them safely for you, free of charge. Just send them to me.
Joke aside, they will not harm you. Just don`t do anything stupid with them: sleep with them, eat them, ingest them, carie them in your pans every day...
--
www.TaraMountain.com
www.PlaninaTara.rs
Joke aside, they will not harm you. Just don`t do anything stupid with them: sleep with them, eat them, ingest them, carie them in your pans every day...
These are the my lenses.
I think these are the radioactive ones..
Olympus Zuiko 50mm F1.4 Silver Nose
Canon FL 50mm F1.8
Auto Takumar 55mm F1.8
Super Takumar 55mm F1.8
I don't know about the others
--
www.TaraMountain.com
www.PlaninaTara.rs
Utterlyotter
Forum Enthusiast
Rumor has it that George Bush Sr frequently had one of those hanging from an unusually long strap 1-2 years before George W. was born.I have some legacy lenses. Should I be worried about the radioactive lens?
Are these some sort of dangerous? I always imagined "the hulk"!
Please be careful... ;-)
The yellowest lens elements I've seen were in a 1950's Bausch & Lomb lens, almost brown from radioactive changes.
donaldsc
Senior Member
Unless you plan to strap the lens to your testicals and leave it there for a really long time, I would not worry about it.
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