Archived posting to the Leica Users Group, 1999/08/02
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I'm just passing on information from an interview with an ex- Leitz employee who left Wetzlar in about 1969. His knowledge comes from the Leitz family. Perhaps there was a prototype that got out? Ed On Mon, 2 Aug 1999 LEICAMAN56@aol.com wrote: > Ed, > > I call your attention to an article in the LHSA Viewfinder 29/3, third > quarter 1996. > > In an article on the early 50/2 Summicrons, Bill Gordon wrote a well > researched article about the use of thorium oxide glass in these lenses. > Bill reports low but measurable levels of radiation from these lenses as > tested by a Geiger counter. He also cites an earlier report by Dr. Cyril > Blood in the Leica Historical Society Newsletter on the use of thorium oxide > by Leitz in the Summitar* and early Summicron lenses. According to Bill, > Leitz never officially acknowledged the use of these radioactive elements. > This is understandable in that they would not want to alarm employees or > users of the radioactive elements in these lenses. Many other manufacturers > of optical lenses also used this radioactive glass. > > If radioactive thorium oxide was not used in the early Summicrons, how do you > explain the positive readings obtained with a Geiger counter? > > Bill Rosauer >