Binocular lens-barrel for stereoscopic microscope

PURPOSE: To obtain constitution suitable to an observer in human engineering by arranging two roof prisms on the exit face of a direction turning prism in a prism element group so as to be positionally deviated from the optical axes of partial optical paths. CONSTITUTION: This binocular lens-barrel having at least one optical direction turning element arranged in common to two partial optical paths so as to be optionally rotated around a rotational axis and at least one optical image inverting element is provided with a prism element group constituted of a direction turning prism 3 and two roof prisms 4a, 4b to be optical image inverting elements are arranged on the exit face of the prism 3 so as to be positionally deviated from the optical axis 11a, 11b of the two partial optical paths. Thereby an interval between two optical axes of the partial optical paths can be extended after passing the optical elements, space for turning the elements can be correspondingly and more widely utilized and the adjustment of an interval between pupils by a rotatable deflected diamond prism can remarkably easily be executed.