In the following video we can very clearly see the way in which the Self Cleaning Sensor Unit that is present in the new Canon EOS 400D - and which will presumably be present in all the next reflex of the company - works.

The system is automatically activated when the camera is connected and causes the low pass filter to vibrate during a second. If we cannot wait and need to shoot immediately it stops as soon as it detects that we press the trigger.

If despite this, we continue having problems of filth in the sensor, we will always have the option of using the new tool of the Digital Photo Professional application of Canon for this end. For this we take a photo of a white surface with an opening as reduced possible (greater f number) and the program takes charge of eliminating the constant pattern of filth.