A March 1950 ad by Kodak touting the use of Lanthanum glass in its lenses
Toronto. When I first saw this March 1950 ad for a Kodak lens that used Lanthanum, I immediately thought about the radio-active Leitz lenses I remembered reading about.
To create unique glass characteristics, many glasses were melted with pinches of stuff like rare earths such as Lanthanum added. I looked up Lanthanum and learned that most Lanthanum is inert – except that there is a very small percentage of a Lanthanum isotope that is radio-active.
Looking further the next day, it turned out that certain high end lenses from the 1950s were indeed slightly radio-active due to using elements made from glass with slight amounts of Thorium Oxide which is radio-active with a very long half life.
So indeed some 1950 era lenses were slightly radio-active – but not from using glass made with a touch of Lanthanum rare-earth added!
Thanks to my good friend, George Dunbar for discovering and sharing the March, 1950 ad from Popular Mechanics.
