An endoscope eyepiece grasping mechanism comprising: - a base part comprising a base portion with a radially inward light passage and an outer surface and a base part arcuate wall portion disposed radially outward of the light passage, the base part arcuate wall portion extending axially from the base portion and extending a circumferential distance between base part arcuate wall portion circumferential ends and defining a base part arcuate wall portion wall opening between the base part arcuate wall portion circumferential ends; - a rotatable part with a radially inward surface, the rotatable part comprising an annular portion, and a rotatable arcuate wall portion including an axial surface extending axially from the annular portion and including a coupling edge with a radial surface extending radially inwardly from the axial surface, the rotatable arcuate wall portion extending a circumferential distance between rotatable part arcuate wall portion circumferential ends and defining a rotatable part arcuate wall opening between the rotatable arcuate wall portion circumferential ends; - a path guide formed between the base part and the rotatable part for guided movement of the rotatable part relative to the base part for moving the rotatable arcuate wall portion relative to the base part between an open state, with the rotatable part arcuate wall opening and the base part arcuate wall portion wall opening at least partially overlapping to define an eyepiece receiving spacing and with the radial surface spaced from the base portion by a first axial distance to define an endoscope eyepiece side opening and a closed state with the rotatable part arcuate wall opening and the base part arcuate wall portion wall opening not overlapping or overlapping to an extent to provide a gap that is smaller than the eyepiece receiving spacing and with the radial surface spaced from the base portion by a second axial distance, which second axial distance is smaller than said first axial distance; and - a biasing device acting to bias the rotatable part toward the closed state, whereby an endoscope eyepiece may be pushed through the endoscope eyepiece side opening to a coupled position in the open state and the rotatable part rotates to the closed state and the radial surface moves axially toward the base position to retain the eyepiece in the coupled position. - a base part comprising a base portion with a radially inward light passage and an outer surface and a base part arcuate wall portion disposed radially outward of the light passage, the base part arcuate wall portion extending axially from the base portion and extending a circumferential distance between base part arcuate wall portion circumferential ends and defining a base part arcuate wall portion wall opening between the base part arcuate wall portion circumferential ends; - a rotatable part with a radially inward surface, the rotatable part comprising an annular portion, and a rotatable arcuate wall portion including an axial surface extending axially from the annular portion and including a coupling edge with a radial surface extending radially inwardly from the axial surface, the rotatable arcuate wall portion extending a circumferential distance between rotatable part arcuate wall portion circumferential ends and defining a rotatable part arcuate wall opening between the rotatable arcuate wall portion circumferential ends; - a path guide formed between the base part and the rotatable part for guided movement of the rotatable part relative to the base part for moving the rotatable arcuate wall portion relative to the base part between an open state, with the rotatable part arcuate wall opening and the base part arcuate wall portion wall opening at least partially overlapping to define an eyepiece receiving spacing and with the radial surface spaced from the base portion by a first axial distance to define an endoscope eyepiece side opening and a closed state with the rotatable part arcuate wall opening and the base part arcuate wall portion wall opening not overlapping or overlapping to an extent to provide a gap that is smaller than the eyepiece receiving spacing and with the radial surface spaced from the base portion by a second axial distance, which second axial distance is smaller than said first axial distance; and an open state, with the rotatable part arcuate wall opening and the base part arcuate wall portion wall opening at least partially overlapping to define an eyepiece receiving spacing and with the radial surface spaced from the base portion by a first axial distance to define an endoscope eyepiece side opening and a closed state with the rotatable part arcuate wall opening and the base part arcuate wall portion wall opening not overlapping or overlapping to an extent to provide a gap that is smaller than the eyepiece receiving spacing and with the radial surface spaced from the base portion by a second axial distance, which second axial distance is smaller than said first axial distance; and - a biasing device acting to bias the rotatable part toward the closed state, whereby an endoscope eyepiece may be pushed through the endoscope eyepiece side opening to a coupled position in the open state and the rotatable part rotates to the closed state and the radial surface moves axially toward the base position to retain the eyepiece in the coupled position.