Abstract: A compact, portable microscope for use in the field is provided with: an optical path extending within the microscope casing between a viewing port and an eyepiece element, which path is folded by a plurality of reflectors; and a cam and follower microscope focusing mechanism. The cam and follower microscope focusing mechanism is configured such that an objective lens element is moveable relative to a substantially planar viewing stage comprising the viewing port. A first portion of the folded optical path between the viewing port and a first reflector extends in a first plane substantially perpendicularly to a second plane in which the remainder of the optical path extends.