OPTISCHES GERÄT

An optical apparatus is disclosed which is capable of preventing degradation of image quality caused by an ND filter. The optical apparatus includes an aperture stop (9, 9a, 9b) having an aperture variable in size, and an ND filter (9f) movable with respect to the aperture of the aperture stop, an actuator (9c) that drives the ND filter, and a controller (37) that controls the actuator. The ND filter includes a part (9f3) having a size that can fully cover a first aperture that is the aperture with the aperture stop being narrowed. The controller (37) controls the actuator so that the ND filter (9f) is moved without a halt between a first position where the part is retracted with respect to the first aperture, and a second position where the part fully covers the first aperture in any stop operation.