Archived posting to the Leica Users Group, 2007/11/08
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I believe low-E glass coatings suppress infrared, either way those coatings don't do much for UV. The UV you would need to reverse the coloration would be quite a bit more then found on a windowsill. About one month continuous 24/7 exposure would do the trick. Best to get a UV lamp and a tinfoil lined box. At 05:10 PM 11/7/2007, you wrote: >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 > > > >_______________________________________________ >Leica Users Group. >See http://leica-users.org/mailman/listinfo/lug for more information Chris Saganich, Sr. Physicist Weill Medical College of Cornell University New York Presbyterian Hospital chs2018@med.cornell.edu Ph. 212.746.6964 Fax. 212.746.4800 Office A-0049