A viewer for viewing an object under magnification, the viewer comprising : an objective lens for producing an image of an object located at an object plane and having a radial extent defined by an aperture stop; a partially- transmissive reflector for allowing transmission of light therethrough from the objective lens to a mirror arrangement and providing for reflection of light which is returned thereto from the mirror arrangement; a mirror arrangement which receives a light component from the partially- transmissive reflector, and is located such that a focussed image of the object is produced at the mirror arrangement and light received by the mirror arrangement is reflected back to the partially-transmissive reflector and relayed to produce an image of the object; a viewing lens arrangement for producing an optical image of the object which is viewable by an observer at an exit pupil at a viewing plane; wherein the objective lens has a beam path angle (a) as defined by a distance from the object plane to the objective lens and a radial extent of the aperture stop; wherein the viewer has a viewing angle (ß) as defined by a distance along an optical axis from the mirror arrangement to the viewing plane and a radial extent of the exit pupil at the viewing plane; wherein the viewer is configured such that a displacement ratio of the beam path angle (a) to the viewing angle (ß) is at least 3 : 1, whereby the observer is provided with a greater change in depth perception of the object being observed relative to an extent of displacement of a head of the observer.
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