The Truth About Vintage “Radioactive” Lenses: Watch the Entire Video Before You Freak Out

Have you ever noticed a yellow tint to the glass in a vintage lens? That may be because certain lenses in the 60s and 70s used a Thorium coating that yellows over time. Thorium has a high refractive index that improves light transmission, but it also turns out to be slightly radioactive.

To determine the danger, if any, posed by radioactive optics, Lens Guru Mathieu Stern conducted a few tests. Hint: The video below is a bit tongue in cheek and has a happy ending.

Stern spent a week eating, sleeping, working, and even showering with a Thorium-coated lens by his side. He also purchased a rare lichen plant that is unusually sensitive to radiation to see if it suffered any ill effects when exposed to his lens. Bottom line: You’d have to spend four months inside a room with two million “radioactive” lenses to fear for your life.

You can find a variety of interesting videos on Stern’s YouTube channel, and be sure to check out his earlier tips we shared for safely removing mold from vintage lenses.