A: Can you detect radiation with a regular camera?

As always, we need to split the main question:

• what type of sensors is used in cameras
• is it possible to trigger the events by radiation
• are there any physical barriers that could stop radiation

Camera sensors

Basically all the cameras on the market use either CCD sensor or CMOS. In post-2000 research papers, it was described that CCD could be used as dosimeters for gamma and there are also some papers in which CMOS was used for X-rays.

Both types of sensors work on the same principle - photoelectric effect.

In theory, it is possible!. There are photos from Fukushima with the unusual noise pattern caused by γ radiation.

Is it possible to trigger the events?

Radioactive lenses are emitting two types of radiation, α and β^-.

Penetrability of α particles is very low, order of magnitude is tens of microns in silicon. Succesfull test was conducted with ²⁴¹Am, 33 kBq, distance between the source and the image sensor 9 mm.

(*flange distance on mirrorless systems is about 15 mm, and about 45 mm for dSLR, and the activity of camera lenses is measured in tens or hundreds of Bq)

For β^- it's more difficult to compare the measures as different isotopes with the different energy of decay were used. As β^- can penetrate much deeper, the effect on a thin sensor is actually lower.

If exposition is long enough... It could be possible

Physical barriers

This is probably the most disappointing part of the answer.

Unless the camera is modified, there is a Bayer filter in the front of sensor which is about 0.5 mm thick. There is an option to remove it and replace with IR filter (filter, again) or even to remove it completely. If it's completely removed, it will be possible to detect α particles. Otherwise, α will be stopped before reaching the sensor. Even the flange distance of dSLR could be problematic for α particles as they can be stopped after travelling about 3-4 cm through the air.

The same goes for β^-. In this case, air is not a problem, as β^- can travel between a meter and 10 meters. It depends how much MeV they carry. Unfortunately, in glass, plastic, silicon, penetrability will be somewhere between 1 mm and 1 cm. In other words, the only way to put some beta particles on the sensor is to have completely clear path between the lens and the sensor.

Now, the worst part: Thorium glass is used almost exclusively in concave elements. Finding the lens with radioactive front element will be difficult, but not impossible. This 35mm f/2.0 Canon for example. Only if the last element is emitting radiation, it will be possible (*theoretically) to detect something.

Final verdict

Only, maybe, if... :

• you take a mirorless camera (to get as most alpha as possible)
• with removed filter (not IR conversion, completely removed)
• lens with the last element radioactive
• and use incredibly long exposition (for beta or "reasonably long" for alpha)

Maybe it could be possible to get some effects.

In any practical situation - probably not.

Bonus Q:

@lemouth, @maticpecovnik - Do you have any idea about suitable DIY solutions? Something to act as scintillator... A naphthalene-like organic molecule, some inorganic crystals (NaI. Once the Bayer filter is removed, sensor can detect anything from 350-1050 nm or even further to the IR side, maybe up to the 1350 nm

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