lars_bergquist Posted March 21, 2009 Share #21 Posted March 21, 2009 Advertisement (gone after registration) As far as I know only the prototypes (including the 'Summitar*' lenses) and maybe the very first small batch of the first version collapsible 50mm Summicron had the radioactive glass. It does not seem to be known, in terms of lens numbers, exactly when the change was made. The old man frm the Age of the Manhattan Project Link to post Share on other sites More sharing options...
Advertisement Posted March 21, 2009 Posted March 21, 2009 Hi lars_bergquist, Take a look here radioactive glass used in Leica lens in 1950s. I'm sure you'll find what you were looking for!
StS Posted March 21, 2009 Share #22 Posted March 21, 2009 We can start to narrow this down, the serial number of mine is starting with 1194xxx and has a violet coating. In fact, when I bought the collapsible summicron with the M3 (both from 1954), I remember wondering about the antireflective coating looking like a modern one (although I'm sure it will be a single layered one). However, I wouldn't bother, if my lens would have such an element - as Jaap has pointed out one has to go through a quite unusual procedure to get a chance to make this harmful. I would assume it's not covered by the user's manual Link to post Share on other sites More sharing options...
rob_x2004 Posted March 21, 2009 Share #23 Posted March 21, 2009 Gee I'm still not convinced. Try licking it and see if your head begins to glow in the dark. Link to post Share on other sites More sharing options...
luigi bertolotti Posted March 21, 2009 Share #24 Posted March 21, 2009 Gee I'm still not convinced. Try licking it and see if your head begins to glow in the dark. I lick TWICE A DAY all my lenses (including some BIG Telyts) : at morming, just arised, and before going to sleep... addicition has made me smarter, and the coatings have earned something too...:D Link to post Share on other sites More sharing options...
farnz Posted April 2, 2009 Share #25 Posted April 2, 2009 I noticed today that the 7th edition of the Hove Leica Pocket book says about my v1 135/4 Elmar (1960): "... the new lanthanum glass has been used to the full ...". I haven't noticed mention elsewhere that any Elmars contained potentially radioactive glass and the elements don't appear yellowed - am I misinterpreting the presence of lanthanum as a radioactive element (in its La 138 isotope)? (Fwiw, I'm not concerned about the levels of radiation for the reasons stated earlier, particularly that the presence of naturally occurring Radon gas and over-enthusiastic medical people will potentially present a far higher dose.) Pete. Link to post Share on other sites More sharing options...
veraikon Posted April 2, 2009 Share #26 Posted April 2, 2009 Lanthanium only one but zt isn´t the "main" problem - it is Thorium Thorium - Wikipedia, the free encyclopedia You will win La from the most common rare-earth thorium-phosphate mineral monazite, which may contain up to about 12% thorium oxide. And it is difficult to separate.... Link to post Share on other sites More sharing options...
kenneth Posted April 3, 2009 Share #27 Posted April 3, 2009 Advertisement (gone after registration) Hi, I heard that there was a kind of radioactive glass used in Leica Summcron-m 50mm lens around 1950s. Because of its radioacvtie, Leica built a factory in countryside for it. I am not sure the type of the lens and, will it make bad effect to its users health? Thanks! It was mainly used so the authorities could detect spies going though customs with a gigacounter joke Link to post Share on other sites More sharing options...
johnastovall Posted April 3, 2009 Share #28 Posted April 3, 2009 If you have granite counter tops, they are most likely more radioactive than any lens doped with Thorium. Some types of granite meets radiation levels of assigned to low level radioactive waste. The background count in the center of Texas state capital's rotunda of the is higher than the background count outside the building. This is due to the presence of Uranium, Thorium and Radium in granite. So, if you are worried about the radioactive of lenses, stay out of granite building, don't have granite counter tops and avoid cemetaries with a large number of granite markers. Link to post Share on other sites More sharing options...
pop Posted April 3, 2009 Share #29 Posted April 3, 2009 ... avoid cemetaries with a large number of granite markers. Thank you for your advice. I will instruct people not to install a granite tombstone on my grave. Link to post Share on other sites More sharing options...
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