Radioactive lenses - a worry?

I have read on several sites about radioactive Leitz lenses. Seems the

"rare earth element" lanthanum used in lenses made in the early 50s,

such as my Summicron, is radioactive. There's possibly thorium too.

Should I worry? Is this the reason these lenses always get such

"glowing" reviews?

I've never worried about it. In fact, the third eye is quite convenient when using a shoe-mounted auxiliary viewfinder. ;-)

 

Seriously, I've not seen readings of the actual radiation levels, if any, actually associated with such "rare earth element" lenses. Another urban myth perhaps?

Ralph, Love the comment!! - still laughing!

I've got an old 55mm Olympus Zuiko f/1.2 - pretty certain that its one of the optics in question!!

I've never noticed any changes (minute differences in density, fogging) in 400 speed film, whether the lens is stored in close proximity, over a period of time, or not. I imagine any radioactivity must be very minimal - by the way, I've noticed an increase in night vision capability with the new eye!!

Just don't swallow the darn thing!

Shutterbug ran an article on radioactive lenses from the 50's and 60's with rare earth elements a few years ago. I don't remember the year or month. The list wan't comprehensive and I don't recall which if any Leica lenses were included. Their opinion was that you could sleep with a box of these lenses under your bed without measurably increasing your health risk. To demonstrate the radiation levels, they placed several lenses front element down on sheet film for several WEEKS. This film showed round patches of fogging to various degrees where the lenses were placed. Keep in mind that the lens elements were much closer to the film than they would be in a camera and the exposure was over several weeks time. For normal use on a camera the radiactivity will have NO effect on the film.

<a href="http://people.smu.edu/rmonagha/mf/radioactive.html">Radioactive Glass in Lenses

Are Your Lenses Really "Hot"?!!

by Robert Monaghan</a>

Better night vision sounds good. Now I see how they developed "Leica

lenses with eyes" for the M3. And the famous "Leica glow". Sounds like

it's not too much of a worry, but always good to find out more.

And thanks to Kelly for the link. Lots of comments and info, but the

jury seems to be out on whether or not radiocative lenses are a

concern:

 

"Just how radioactive are typical "hot" lenses? Studies of a half

dozen Leica lenses (see postings below) came up with 1.5

milliroentgens/hr. This figure compares to 20 milliroentgens (mrem)

per day maximum permissible dosage in many western countries. But that

20 mrem is for whole body exposure, while the lenses mostly emit

shorter range beta and alpha particles. On the other hand, it may take

just a single gamma ray to turn one of your cells into a cancerous

cell and cause a tumor. These 1.5 mrem/hr levels are surprisingly high

compared to typical levels for radiation sources used in scientific

and civil defense training (often 2 or 3 orders of magnitude lower

levels). Don't tell OSHA or the EPA, or all those collectible Leica

lenses may end up in a secret government landfill! "

Dear Leica forum members.

 

It has come to the attention of the Atomic Energy Commission and the Environmental Protection Agency that several of you are in possession of the above mentioned "Leica" lenses. These lenses violate minimum safety standards for radiation emission as specified by law. Under the right of eminent domain, and said law, please surrender immediately all such lenses in your possession to the appropriate representative of the United States Department of Energy. Further details may be obtained by contacting said representative at the following email address.

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Kelly, you're a genius! ROTFLOL!!

 

:-D