Archived posting to the Leica Users Group, 2007/11/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]LOL. Yes a little extreme. ;-) Thanks, Graham. Len On Nov 7, 2007, at 5:41 PM, geebee wrote: > From: "Leonard Taupier" <len-1@comcast.net> > > Subject: [Leica] OT: Fixing radioactive lenses > > >> I have an old Pentax 50/1.4 Super Takumar that has, over time, >> yellowed due to one of the elements containing Thorium, a mildly >> radioactive element. The addition of thorium makes a very high >> refractive index glass, and a very good lens. This lens is >> probably one of the most famous lenses with this element but I'm >> sure there were more. >> The fix for removing the yellow cast to the lens is to expose it >> to a UV source like sunlight or a UV light for a week or more. I >> have been putting the lens in a window during the day and exposed >> to a black light at night. >> My question is concerning the glass used in my windows. They are >> made of high E glass and have an air space between the double >> panes. I know high E glass is supposed to suppress Infra Red but >> I see no info on if it passes Ultra Violet which is at the >> opposite end of the light spectrum. Does anybody know? >> Thanks, >> Len > ---------------------------------------------------------------------- > ------------------------------ > > One man's remedy for the yellowing. May be a little extreme for > your purposes :-) > http://www.hermes.net.au/bayling/repair.html > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information