Canon EOS R5 C User Manual page 661

Cleaning Manually
Dust that could not be removed by automatic cleaning can be removed manually with a
commercially available blower or similar tool.
Always use a fully charged battery.
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.
Select [Clean manually].
2.
Select [OK].
3.
Remove the lens and clean the sensor.
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