Abstract: A sub-stage, dual-turret assembly provides a rapid interchange of condensers and birefringent elements without sub-stage assembly, disturbance of illumination system, refocusing the microscope or dislocation of the object being studied and minimizes storage problems normally associated with maintaining convenient access to a selection of interchangeable delicate optical elements. The assembly has an upper turret normally adapted to carry at least two condensers and a lower turret usually adapted to carry a plurality of birefringent elements. The two turrets are independently rotatable in order to provide maximum versatility.