I recently visited the Chernobyl exclusion zone the pictures of the damaged reactor of the power plant were slightly faded, I suspected it was due to the background radiation.
I figured it was easy enough to test how radiation affects digital CMOS-sensors so I irradiated my Nikon to see what kind of effects would I get.
Exposing the camera to radiation
I built a rig to expose my camera to different levels of radiation. Two radioisotopes were used as radiation sources, Cobalt-60 which is a strong Gamma-emitter and Cesium-137 which emits Beta-particles. These yielded the highest activity levels of my samples.
In the measurements I used my trusty Russian dual-tube RADEX RD1706 Geiger Counter with a custom sticker in it.
Rig contained a lab stand holding the Geiger-counter, camera which had its sensor set the same height from the table and a laboratory scissor jack to rise and lower the isotope sample.
The gamma-emitter was covered with 8 mm aluminium sheet to block any Beta and Alpha-particles from reaching the sensors. For Cesium-137 paper envelope was used as an Alpha-shield. Lens was removed from the camera and replaced with thin plastic body cap.
I took 11 measurements with both isotopes from different heights swapping the lab-elevator under the the Geiger-counter and camera. Pictures were taken in RAW-format with 30 second exposures to maximize the amount of interference in the shots.
Radiation produces spots in the image that are caused by high energy particles hitting the CMOS-sensor. When the ray is absorbed by the electrons in the censor, they get exited and soon release their excess energy as a flash of light.
Unless the radiation is affecting the control and processing circuitry of the camera, anomalies seen on the images are not caused by ionizing radiation.
- Camera did not take any damage during the tests
- Ionizing radiation can be picked up by camera’s CMOS-sensor
- High energy particles cause bright dots in digital images
- Remember to switch off camera’s manual mode if not using it