Mirror cleaning

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The mirror of an SLR camera should be periodically inspected for dust and grease. Dust and grease enter the chamber when lenses are changed, and the vigourous action of the mirror then moves particles around the chamber.

The mirror is not in the optical path to the film or sensor, but it is in the path of the autofocus mechanism, so substantial debris on the mirror, especially smearing, can affect performance.

Dust can be removed easily with a blower or mirror brush. Smears can only be removed with a specialist cleaning solution. Care must be taken not to apply any force onto the mirror, which could damage the mechanism.