Archived posting to the Leica Users Group, 2000/01/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> OK, but this doesn't address my initial question, unless I'm supposed to > derive from this that there is no effect on film, since the lens *was* > purposely designed with one or more radioactive elements. > > Or, perhaps, you just make sure that the film doesn't sit in the > camera for any length of time. I'd be interested in actually seeing one of the radioactive lenses leaving a fogged piece of film. According to my wife [who does radioactive particle analysis for a living], distance would play a crucial role in whether the film was exposed or not by the Thorium elements. According to her, the alpha particles would not expose film outside of a fairly short distance [~2 inches or less, depending on some variables], while gamma particles would travel several yards. Take the following examples: - - The Staticmaster brushes you use on your negatives have radioactive alpha emitting polonium in them, but it poses no danger unless you shove your fingers inside the metal guard cage, rip out the metal patch that actually contains the material and have physical contact with it. However, if you stick the metal cage of the brush very close to your eye for an extended period, it will burn your cornea. - - The old Coleman gas lantern mantles containing alpha emitting Thorium that everyone used while camping [the new ones are safe]. You were fine as long as you didn't touch or breath the mantles or the dust they turned into when they were jarred. - - The high tech watches that have the little glass vials full of glowing Tritium gas that lasts for many years. As long as the tiny glass vials don't break, you are safe from the beta emitting gas, the same material that is used to enhance nuclear weapons. /Mitch