The DSLR sensors do return a signal even in complete darkness. This signal is due to the thermal movement of the electrons. The atoms, excited by the heat, are expulsing some electrons from time to time, the heater the merrer. These electrons are then analysed by the DSLR electronic such as the "real" electrons generated by the photons. This current is called the "dark current". It is proportional to the exposure time and increases with the temperature.

A common rule of the thumb says that the dark current doubles every 6 to 8 °C. This article tries to measure the law of the Canon EOS 1000D sensor.

Key word : Canon EOS 1000D, dark current, temperature