Archived posting to the Leica Users Group, 2006/05/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Greg, The yellow cleaned up so it is not decaying balsam. Another way to test the lens is to leave it on a piece of film(the thorium element were in the front group) for say a day and process the film. No fog, no radiation, nice circular fog, then indeed a yellow glass Summicron. It really doesn't matter, the signature of both sets of lenses is very similar with the latter design somewhat superior as they could use the high diffraction elements in the last group when it became radiation free. Don don.dory@gmail.com On 5/24/06, GREG LORENZO <gregj.lorenzo@shaw.ca> wrote: > > Don Dory writes in part: > > > Greg, > > Your lens lies beyond the serial number range for the thorium > > glass lenses. > > Don, > > I've seen the Serial Numbers for the Lak9 Summicrons extend to 104XXXX. I > believe you may be confusing the Summicron serial numbers with the Crown > glass that Leica obtained from a British glass supplier. Most of these lens > were Summicrons in Summitar clothing. > The 104XXXX lenses were made in 1952. 1953 was the first year that Leica > advertised 'rare earth' Summicrons. > > Best way to confirm whether a particular lens is hot or not is with a > Geiger Counter. Something I don't happen to keep handy. However, if your > yellow glass Summicron imparts a warmer cast when shooting slide film it is > most likely a rear earth lens. Otherwise it is most likely the result of > decaying balsa glue. I'll ask number 1 daughter to check if her high school > physics lab has a Geiger Counter. > > Regards, > > Greg > > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >