Should I be worried about these lenses? Radioactive? Help.

Hi,

I own three very old large format lenses that seem to have rare

earth material which turned brownish. I have seen discussions which

mentioned some radioactive material in some of the older lenses.

Should I remove these lenses out of my home or are they safe to keep

around as long as I don't open them up? The lenses are very large

(for 8x10) with huge diameters. I would appreciate useful advice in

my situation. Thanks in advance.<div></div>

Radioactivity is known for fogging film--perhaps film samples can be used to assess the danger?

Raid,

 

First, the brownish color is no sure indicator of radioactivity. You could probably contact a college or university that has a physics department for a survey. The lenses would be safe even if you do open them up, the radioactivity is held in the glass if there is any. I've never seen any that would be a hazard, and the Nuclear Regulatory Commission and its counterparts in Europe and other countries place limits on how much radioactivity can be used in consumer products, at least since WWII. BTW, I do this for a living - it buys my camera gear.

 

I would not sleep with one under my pillow every night or store them under the baby's crib, just as I wouldn't with a radium-dialed alarm clock, a piece of old orange Fiestaware, vaseline glass, or other radioactivity-containing product. Many naturally occurring rocks and sand contain similar amounts of radioactivity.

 

If you're still worried, you can send them to me!

 

Steve

<p>My standard advice is what Steve says -- keep far away (at least several yards) from the lenses when you are not using them -- the inverse square law will greatly reduce the radiation level. I have a few comments on the hazard level on my webpage about Aero-Ektars: <a href="http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html">http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html</a>. I don't want to get into detailed computations of risk, etc., because I haven't had time to do a careful calculation and I don't want to make the decision for other people.</p>

 

<p>As Steve mentions, there are many other items available to consumers that are radioactive, and thorium isn't highly radioactive. Most of these items were made before today's regulations about radioactivity, but experts of the US Nuclear Regulatory Commission have thought about the hazards of the items that are out there. Such calculations are, no doubt, behind the regulation that specifically makes possesion of thorium-containing glass legal (see my webpage).</p>

 

<p>As least with experience, the brown coloration is a pretty good indicator of thorium glass. I have heard that balsam cement aging can look similar, but I have never seen the same uniform tea-colored shade from balsam. Also, with some of these lenses you will increase the radiation level if you disassemble the lens, e.g., with most of the Aero-Ektars the thorium glass is in interior elements, and the radiation level on the surface of these elements is significantly higher than on any surface of the exterior of the lens. As Steve says, even if you take a lens apart, the radioactivity will still be trapped in the glass.</p>

 

<p>As Zack says, you can test for radioactivity by exposing film -- significant fogging will probably take a week or more. Or you could tell us the specific names of the lenses and someone might know the answer. Or take them to a physics department and ask if they can check with a geiger counter or other radiation detector.</p>

 

<p>Some relevant info on photo.net: an example auto-radiogram by Arne Croell at <a href="http://www.photo.net/photodb/photo.tcl?photo_id=1221738">http://www.photo.net/photodb/photo.tcl?photo_id=1221738</a>, a discussion of Repro-Clarons and Aero-Ektars at <a href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=004cye">http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=004cye</a>, and on using UV light to remove the brown color at <a href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=005obo">http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=005obo</a>.</p>

 

<p>There are many thorium containing lenses out there, including some relatively common ones for 35 mm cameras.</p>

I have never used this old camera since it is "incomplete". I don't have the film back for it. Thanks for the advices. I certainly don't sleep with it beside me :-) I may check out a geiger counter from the physics department at my university, just to be on the safe side.

Thanks agin.

Hi Michael,

I have exchanged with you some email a yewar ago or so regarding my camera. I am a little concerned that the lenses are only two yards away from me in this room. Should I get a Geiger counter, as recommended here, or maybe just move the lenses to the garage?

Since my lenses are quite large, then the amount of radioactive material may be greater than in smaller lenses. What do you recommend to me to do here?

The specific names of the lenses are as follows:

 

1. Kodak Ektar 362mm f1.66

 

2. Bausch & Lomb 14.5 inch f2.2 (I have two of them)

I have one of the putative radioactive Super Takumar lenses on my Spotmatic. I've had the lens for around 20 years, and keep it mounted on the camera, which is usually loaded with ISO 400 film and in a bag with other rolls of ISO 400 film. I've never seen a trace of fog, which I would expect to be the case if radiation from thorium in the glass were a hazard.

 

I'm not an expert on radiation -- I repair nail guns for a living -- but I know a little about it and the above advice is well taken. Beta and especially alpha radiation aren't great penetrators -- alpha from a lens wouldn't penetrate other elements or the lens barrel in sufficient intensity to be of any concern. Beta is the greater concern, but is still unlikely to be a hazard if nearby fast film isn't affected. Try leaving the lens in a dark location for a few days, on top of a piece of film in a light tight plastic or paper wrapper. If it emits sufficient radiation to be hazardous, I'd expect you to see significant fogging in a pattern that will look like the lens element or barrel.

A Geiger counter clicks abit to all three of my Kodak Aero Ektar 178mm F2.5 lenses. Also it clicks abit to a Kodak printing Ektar lens. None of my Russian lenses registered. Several unused packs of Coleman mantles from the 1970's also clicked the Geiger counter the same amount. A buddy brought his Surplus meter; we checked everything in the house. It has a calibration patch on the side that is radioactive; it is old; and just a rough uncalibrated meter now. It is the more sensitive type of meter. An old neon tube in a voltmeter clicked abit too. These were in the feedback loop of a DC Differential Voltmeter. The neon tubes that are radioactive have a lower voltage to fire the tubes. Newer replacements are non radioactive; and dont last as long. <BR><BR>New type Coleman type mantles are not radioactive; at least the ones we see around here. The radioactive ones are still sought out; for Physics experiments etc.<BR><BR>Two of the lens groups in the 178mm F2.5 Aero Ektar are radioactive; I have one of my three lenses apart. These two lens groups are behind the iris; and are closest to the lens. The rare earth elements on mine are tea colored; and radioactive.<BR><BR>Never use a radioactive lens as an eyepiece. Reduce your exposure to these lenses; move them in another room; when not in use. Dont keep them under your bed; on in your pants pocket. <BR><BR>Some glassware is radioactive too. Some cheap imported cups and dishes contain lead; and are probably a much bigger danger; even more so to kids.

Is it safe to be about 2-2.5 yards away from such lenses?

I don't know where to store such heavy lenses, especially if walls don't stop radioactive material from reaching you in the house.

My wife asks me to get rid of the camera and lenses. Oh well.

How much of the time are you 2 yards away?

There are four ways to reduce the danger from radioactivity: Shielding, distance, time and getting rid of it...

 

I handle radioactive sources in my job, and we have very strict procedures about everything. But those sources are highly radioactive - the activity is measured in Gigabequerel which translates to billions of counts per second.

 

Shielding doesn't have to be much - every little bit helps. All the alpha radiation is already stopped buy the other elements, along with quite a lot of the beta. Gamma you can't do anything about in a normal home (several feet of lead is probably not an option).

 

Distance works; the inverse square law works for all kinds of radiation. That only means that you shouldn't sleep with hte lens under your pillow. Remember that doubling the distance quarters the radiation - so moving from one inch away to 2 inches gives the same reduction as moving from 1 yard to 2 yards. But moving from one inch to one yard (how much is a yard? 3 feet?) reduces the radiation to about 1/1300 (assuming 36 inches to the yard - I'm "metric", so I can never remember)!

 

Pointing the lens (if it's on a camera) towards the wall will give some shielding from the camera back, as well as maximising the distance. Putting it in a drawer with the radioactive element down does the same.

 

Time doesn't mean you should only use it at exposures less than 1/50th of a second - instead you shouldn't spend unnecessary time in close proximity to it. Don't use it unless you use it: Use it for photography, not for looking through (nor as a letterpress on your desk).

 

As a conclusion, these are fine old lenses which present no hazard unless you go out of your way to create it - by fondling or even ingesting (!). I have radioactive lenses too (APO-Lanthar), and they are among my finest lenses. My dosimeter badge sits right next to my camera case when I'm not at work; if it ever gets too much radiation I'll be looking for a new job. The lenses are not that radioactive!

 

If you are still nervous, increase the distance by sending it to me here in Norway. After all, I'm trained to handle these things ;)

Dear Raid,

 

There are many here who know a great deal more than I but I can make two modest contributions.

 

First, I got an autoradiograph off the rear glass of an Aero Ektar sitting fully assembled, rear glass down, on a sheet of Polaroid 3000 -- in less than 48 hours!

 

Second, the first paper of which I am aware on this subject was in the British Journal of Photography some 10-20 years ago. One of the authors was a friend of mine, Dr. A. Neill Wright, who is a serious lens collector and used to work in the field of radioactive substances. His advice was (and is) 'don't store them under the bed, but don't worry about it otherwise.'

 

There are two generations of 'hot' glass, the first probably due to incomplete purification of monazite sands, in Neill's opinion, and the second where (as far as I recall) ferric and ferrous salts (brown) were bleached to ferrates (colourless) with a radioactive salt: I think of thorium, but I've forgotten, I've mislaid the paper, and I never was much cop on this branch of physics anyway. The first generation (LF, 1940s and early 50s, including the Aero Ektar) is relatively 'hard' or penetrating while the second (mostly Japanese glass of the 50s and 60s) is easily shielded -- even a lens cap will do it -- but VERY dangerous if used as an eyepiece on a telescope (as some were) where the naked eyeball is millimetres from the naked glass.

 

Interestingly, Neill found that some Apo-Lanthars were radioactive and not others.

 

As I say, all the above is from memory and I've not read the paper for several years (it got mislaid on my last move) but I think those are the salient points. Those who know more than I (most people) may find it interesting to look up the paper, perhaps via a web search.

 

Cheers,

 

Roger (www.rogerandfrances.com)

<p>For those who don't recognize the name, Roger Hicks is the author of numerous excellent photo articles and books. In fact, it was his article in a Shutterbug that got me interested in radioactive lenses. Since then I have researched by measuring lenses and reading recent literature (such as the two articles by Frydman and Wright in the British Journal of Photography) and literature from the time period: patents, scientific articles, optic books and some product literature from manufactures. I have to disagree with several of his statements above about radioactive optical glass.</p>

 

<p>From the evidence that I have seen, there are not two generations of thorium glass. (There are of course more than one recipe for thorium glass, with different amounts of thorium.) Optical glass containing thorium intentionally contains thorium for one reason: the very desirable optical properties that it gives: a high index of refraction with low dispersion. All thorium containing glass emits the same types of radioactivity. By now, since thorium glass hasn't been made in years, the thorium is in equilibrium with its daughter radioisotopes. The combination gives off alpha, beta, x- and gamma-rays. The first are relatively easy to shield against. The gamma-rays are more penetrating and won't be stopped by a lens cap.</p>

 

<p>The only other type of radioactive glass that I know of contains uranium. This glass is yellow/green and fairly common in art glass. It is said to have been used for some yellow/green optical filters in the past.</p>

 

<p>Roger is correct that eyepieces using thorium glass could be dangerous. They might be used for long hours (e.g., by a professional using a microscope) and are used in close to the body, in fact to an organ that is more sensitive than the bulk of the human body to radiation. For this reason, the possesion without a license of thorium-containing eyepieces, eyeglasses and contact lenses is illegal in the US -- see my Aero-Ektar webpage. Thorium containing eyepieces are believed to be extremely rare.</p>

 

<p>There are longer explainations of some of this in my Aero-Ektar webpage: <a href="http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html">http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html</a>.</p>

Hello Roger,

I have been thinking about asking you a question for some time. I bought a book by you and Frances, and I noticed that in many photos the Vivitar 90-180 macro zoom was used. I have one too, and it has a brownish cast. I appreciate your input and those of Michael and the other commenters on my question.

I discussed today with someone at the Physics Dept. the situation, and he will next week visit my home with a Geiger counter. He also offered to take the lenses for his Dept. to use them as telecopes ... just what someone warned about in this forum.

I worried abit about these radioactive lenses too; and dont sleep with them :) Then I found out that the old radioactive Coleman Lantern mantles were in a cigar box; in the desk; where my home computer is; below my keyboard. I probably got a million times more exposure to the radioactive mantles; than the exposure to the lenses. The mantels have been in the drawer since the 1970;s' my computer there for several years; with me a foot away. The radiocative lenses were moved a room or two away long ago; while I got daily zapage from the hot old unused "old type" mantles. There maybe another thing more harming than your lenses! <BR><BR>The common 178mm F2.5 Aero Ektar was about 5 dollars in the 1960's ; mail order surplus.The radioactive two elements are of rare earth materials.

I wouldn't worry about Thorium doped lens:

1) Thorium emits *low* energy particles. Depending on the isotope, you get them all, alpha, beta, and gamma. But they are ALL fairly low energy. And since the Thorium is vitrified (incased in the glass) most are adsorbed and never get out.

2) The alpha emissions (a heavy two proton decay particle) are only a problem if you breath or eat a lot of material in a very fine powder form, where the alpha will encounter living cell material before it's stopped. Alphs can't penetrate more than 1 cell thickness.

3) The beta is also weak. Mostly a problem to the lens of the eye. As long as your eye glasses aren't Thorium doped, you're safe.

4) All but one of the gammas are much less than one MeV. Not a big deal. Don't eat your lens and you'll be fine.

 

paul... nuclear engineer, NRC licensed reactor operator

Paul,

I will not eat these lenses. They weigh each over 20 pounds, and I need to lose some weight :-)

Dear Michael,

 

I didn't say there were two generations of thorium glass: I said there are two generations of hot glass. As I said, this was from memory and from conversations with Neill; the 1940s glass being the result of poorly refined monazite sands, and the 1950s glass being the result of thorium bleaches. But you almost certainly know more than I, especially if my memory is at fault. Am I misremembering about ferrates too?

 

I've always said that a good teacher likes to see a pupil who knows more than the teacher, so I guess I must have been a good teacher with that article!

 

Cheers,

 

Roger (www.rogerandfrances.com)

Dear Raid,

 

You know, I've never thought about it? I'd be surprised if a lens this late was 'hot' but I suppose it might be. Unfortunately I now live 400 miles from Neill, not 14 miles, but I'll ask him next time we speak on the phone.

 

Good lens, isn't it?

 

Cheers,

 

Roger (www.rogerandfrances.com)

Dear Michael,

 

An impressive analysis on your web-site. Thanks.

 

Cheers,

 

Roger (www.rogerandfrances.com)

<p>Thorium glass was used in lenses into the 1970s, so if the Vivitar lens that Raid asked about was made before approx late 1970s, it is possible for it to have thorium content. An example of a 1970s lens with thorium: the pre-AI 35mm f1.4 Nikkors -- see <a href="http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=0054IM">http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=0054IM</a>.</p>

Since several Physics experts have been commenting on my posting, I have dug up a link about my mystery camera and lenses. The key person seems to be a Douglas Winnek who invented the Trivision design. Here is the link:

 

www.microlens.com/HistoryofLenticular.pdf

 

It is lengthy, but gives a historical background to the old 3D designs.

Mike,

The Vivitar lens mention is a first-class macro zoom lens. It is extremely heavy and is a flat-field lens. As Roger pointed out, it is a great lens. It was initially manufactured for the medical field to be a "surgery lens"; to document surgery. However, it was too expensive and beacme a "legend". Popular and Modern Photography always referred to it as "legendary". Until recently, it was the only true flat-field macro zoom lens. I know that other owners of this lens have commented on photo-net about the brownish color of the lens. However, one person stated that his 90-180 lens did not display this coloring.

Hello Roger,

Are you referring to the same "Neill" who sold most of his collection to Japan? I recall Bob Shell sending photos of my mystery camera to a collector (maybe Neill) who could not find in his vasr records any mentioning of my camera. I bet it was Neill.

If the camera and lenses are from Winnek's Tri-Vision X-ray system, it would explain the extreme speed of the lenses for their focal lengths. As shown in the HistoryofLenticular.pdf, Winnek was photographing an x-ray image off of a fluorescent screen. The dim image on the fluorescent screen would cause one to want a fast lens. From the 1950s there are Fluro-Ektars for the purpose of making regular (non-3D) images of fluorescent screens -- these are fast lenses that incorporate thorium glass.

 

The HistoryofLenticular.pdf document refers to Popular Science in 1942 and also cites "Winnek", but the last page of the reference list won't display with the readers that I have tried due to some defect near the end of the file.