An optical apparatus has an imaging optical system provided with a deformable mirror and an electronic zoom function that an image recorded in an image sensor by the imaging optical system is magnified by image processing. A ray deflecting function of the deformable mirror is changed in accordance with a change of an object area corresponding to an image to be used, and aberration of the imaging optical system is optimized. The deformable mirror is controlled by an arithmetical unit connected to an image processor and a driving circuit. The electronic zoom is performed with respect to the image recorded in the image sensor through a signal processing circuit and the image processor, and when the image is displayed on a display device, the deformable mirror is deformed so that sharpness at nearly the center of an object image formed on the image sensor is improved. This offers the optical apparatus in which a compact design is achieved, the magnification of the optical system can be changed, and the sharpness of the image is high even when a variable magnification ratio is increased.