Canon EOS-1D C - Manual (Page 297)

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.
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