radioactivity

A Radioactive Lens

Between the 1940s and 1970s, a number of camera manufacturers designed lenses employing thoriated glass in one or more elements. Incorporating as much as 40% thorium dioxide (ThO2) in the glass mixture increases the index of refraction of the glass while maintaining low dispersion. Thoriated glass elements allowed lenses to deliver low levels of aberration and distortion with relatively simple and easy to manufacture designs.

Decades-Old Lenses May Be Radioactive, Especially if They’re Made by Kodak

Late last year, we shared a video in which a photographer tested the radioactivity of an old Pentax 50mm f/1.4 lens that is really popular with film photographers. But that is far from the only lens you have to worry about when it comes to radioactivity.

Camerapedia lists 54 lenses that have been reported as radioactive and that, if you use them often enough, you may want to take note of.