Canon EOS-1D C EOS 1D X Instruction Manual - Page 297

Sensor Cleaning The camera has a Self Cleaning Sensor Unit attached to the image sensor's front layer (low-pass filter) to shake off dust automatically. The Dust Delete Data can also be appended to the image so that the dust spots remaining can be erased automatically by Digital Photo Professional (provided software, p.410). About smudges adhering to the front of the sensor Besides dust entering the camera from outside, in rare cases lubricant from the camera's internal parts may adhere to the front of the sensor. If visible spots still remain after the automatic sensor cleaning, having the sensor cleaned by a Canon Service Center is recommended. Even while the Self Cleaning Sensor Unit is operating, you can press the shutter button halfway to interrupt the cleaning and start shooting immediately. 297