1. Blow away loose particles and dust by means of a
bellows or compressed air (according to ISO 8573:2010
class 1).
2. Get the cleaning liquid and cleaning tissues ready.
3. Move the table up and put a cloth under the lens holder
(so that the lens will not be damaged if it falls out of
holder by accident).
4. Unscrew the lens fixation screw.(1 screw)