Radioactive Takuma Lenses?

[airconvent]

Hi
I just realised that some of these older pentax lenses make use of a mildly radioactve element in their designs. I'm intrigue to know what properties these material impart on the lens and why is it necessary to use them. Are they still being used today?
How do you remove the radioactivity?
Conpared with the Pentax 50 f1.4, any difference in performance (assuming the pentax does not use radioactive stuff).

[fengwei]

Originally Posted by airconvent Hi I just realised that some of these older pentax lenses make use of a mildly radioactve element in their designs. I'm intrigue to know what properties these material impart on the lens and why is it necessary to use them. Are they still being used today? How do you remove the radioactivity? Conpared with the Pentax 50 f1.4, any difference in performance (assuming the pentax does not use radioactive stuff).

Everything about this can be found here:

http://www.pentax-manuals.com/repairs/yellow.htm

And the best cure? Like this maybe?






Cheers


.

[CYRN]

Originally Posted by fengwei And the best cure? Like this maybe? Cheers .

[chantyeroop]

It seems like after the 'repair' procedure, the lens has become BER :- beyond economical repair.