French photographer Mathieu Stern gets this question a lot: What do you think of radioactive lenses? Then comes a barrage of follow up questions like, “Do you think they are dangerous?” “Can I get cancer?” “You would never use that, right?” To put an end to these questions, he just had to put his answer up on YouTube for everyone to watch.
So, there you have it, film snapping, vintage-loving folks. Some lenses from the 1960s to the 1970s (some say all the way to the 1940s, actually), are radioactive because the coating contains a radioactive element called Thorium (specifically, a compound called Thorium oxide). Thoriated glass was particularly used to make high quality lenses with increased refractive index, which means they get more light inside the glass. Over time, lenses with Thorium coating or glass elements get a yellow or yellowish-brown tint, which is an indicator of its radioactivity.
Oh no, so you think you have some radioactive lenses? As Mathieu pointed out in his fun video, a radioactive lens contains only approximately 0.01 milliroentgen per hour (mR/hr). Camera-wiki states that it approaches 1 mR/hr at the surface of the lens and decreases rapidly with distance. For reference, at typical chest X-ray exposes you to around 10 mR, a round-trip cross country airline flight would expose you to 5 mR, and a full set of dental X-rays would expose you to 10 – 40 mR.
Kodak has been found to have widely produced radioactive lenses from the 1940s to the 1960s. However, several other non-Kodak lenses were also reported to be radioactive. Camerapedia has an extensive list here. Still, we wouldn’t worry if you find yours on the list, as the only real danger would be if you use cameras with thoriated glass viewfinders, which is very rare.
Want to find out more about radioactive lenses? You can check out this article by Oak Ridge Associated Universities on Thoriated lenses, and this article by NASA scientist Michael Briggs on the Aero-Ektar lenses by Kodak.
Bottomline: keep shooting and collecting those lovely vintage lenses!
Screenshot image from the video by Mathieu Stern