Solution
If you cannot remove dirt or dust on the image sensor (CMOS) even by using the sensor cleaning function on your camera, you can clean the sensor on your own by using a commercially available blower.
Caution
The surface of the image sensor is extremely delicate. If the sensor needs to be cleaned directly, having it done by a Canon Service Center is recommended.
1. Set the power to [OFF].
2. Detach the lens.
3. Using a commercially available blower, blow dust that is stuck to the surface while preventing the blower from directly touching the sensor.
Caution
The surface of the image sensor is extremely delicate. Clean the sensor with care.
Use a plain blower without any brush attached. A brush can scratch the sensor.
Do not insert the blower tip inside the camera beyond the lens mount. It can damage the shutter curtains.
Never use canned air or gas to clean the sensor. The blowing force can damage the sensor or the spray gas can freeze on the sensor.
If a smudge that cannot be removed with a blower remains, having the sensor cleaned by a Canon Service Center is recommended.