Archived posting to the Leica Users Group, 2007/11/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Graham, Thanks for the reminder. I have seen that previously. However, I prefer to keep my Takumar intact. I have not been able to detect any noticeable yellowing in my sample. Jim Nichols Tullahoma, TN USA ----- Original Message ----- From: "geebee" <geebee@geebeephoto.com> To: "Leica Users Group" <lug@leica-users.org> Sent: Wednesday, November 07, 2007 4:41 PM Subject: Re: [Leica] OT: Fixing radioactive lenses > 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 >