Radioactive lenses, the movies, making an x-ray at home

Here are some videos I shot of the radioactive lenses.

First: holding such a lens near a tube that sends electronic pulse every time a fast electron or a very energetic photon shoots through it. The lens has a thorium lens element at the back, that successfully corrects abberations.

Making an x-ray at home

This Mamiya lens is way more radioactive than the Takumar above. Yet, the exposure to make a photo with a radioactive source like thus, needs to be at least a day and a half. That is because I exposed the film directly. It does not mean that the lens is far less radioactive than a medical X-ray though. It is actually about the same. Note that real X-rays utilizes a fluorescent or "glow in the dark paint” layer, that in turn exposes a green or blue light sensitive film. This is how medical X-rays are so efficient with the same amount of radiation.

I'll try this next. I already bought the paint.

BTW, this is also how green glowing hands and numbers on radioactive watches work. You do not see the radiation directly, but the effect on fluorescent material. If these watches stop glowing, it's because the fluor is gone, not the radioactivity.