RE: [APML]: 300 mm Kodak Areo Ektar?

["Joseph O'Neil" <joneil@multiboard.com>]

The Astro-Photography Mailing List
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At 10:44 27/07/98 -0500, you wrote:
-snip-
>reflection) that many of the older surplus military lenses, and this
>includes essentially all of the aero Ektars, use glass which is fairly
>radioactive.  A lot of the glass was doped with things like thorium,
>uranium, cerium, etc. for the best possible performance, with the logic
>being, "hey, it's wartime, anything goes and what's a little dose in the

        If any of you ever ahve the chance to visit Corning, NY, drop in the
Croning glass museum.  Not only can you see the "spare" blank for the
palomar teelscope, but they have examples of radioactive glass, complete
with geiger counters to show the low level radioactivity.
        Uranium was used in glass aorund 1900 to 1920's to give it a golden
colour, mostly in table ware.  With WW2, the rush was on to develop new
lenses and glass,a nd by that time, realizing some things about
radioactivily, they still wnet ahead.

>process?".  Of course WWII was some time ago and this is now a
>consideration in the here and now.  That said, the two key items they
>mentioned were 1) don't leave the lens in close proximity with your film
>for extended periods of time (fogs the film, natch...) and 2) don't

        Not all lenses from that era are/where radio active, just some of the
"better ones", as uranium was scarce and expensive.   The whole use of
radio active materials during WW2 is rather facinatiing, if not off topic,
but to this day the effects are still seen, be it the Dene Indians
(original miners of the first Urianium used in Fat Boy) up inthe NWT of
Canada who are all dying/dead of Cancer to people who died of mouth &
throat cancer form licking the brushes they used to paint radium watch
dials (to get a fine point).
        Anyhow more to the point radio activiy can affect film, so store the lens
seperately form film.  Look for a yellowish/golden hue to the glass in the
lens, as this is the colour uranium gives to glass.  The table ware I
described earlier was actually more radio active than these lenses as they
used a lot of urainum for a strng golden colour, cosmetic purpose.  In
photo lenses the purpose was more to experiment with optical quaility and
refractive index.

>store the lens in close proximity to your person (some folks stash their
>lens collection under the bed).  Not a good idea in the long term.
>Don't let this put you off using the lens.  These are just precautionary
>notes so that you don't cause yourself any problems in the long haul.

        If I remeber correctly from my tour of the Corning factory some years ago,
the level of radiation put out by some of this glass was very, very low.
If you slept with the lens in your bed you would pick up the equivalent of
a couple dozen dental x-rays over the space of a year, so yes, do not store
it under your bed.
        Unless you are looking for a cheap alternative to vasectomy...
        :)
joe

http://www.multiboard.com/~joneil
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