On 30/01/2013 7:22 PM, RichA wrote:
The Kodak Ektamate and Ektar lenses all use thorium glass. Pretty
harmless just sitting around but I wouldn't want to press my eye to
one for any length of time.

http://www.surplusshed.com/pages/item/l3759.html

What was the purpose of having a glass made of thorium? What was the
advantage?

Yousuf Khan