An optical apparatus including an imaging apparatus and a lens apparatus each having a communicating portion performing communications is disclosed. The optical apparatus is provided with: an imaging optical unit; a memory in which information of an optical performance of the imaging optical unit is stored; an image pickup device imaging a subject image from the imaging optical unit; an imaging controller changing an information size of image information from the image pickup device; and a lens controller connected to the imaging controller through the communicating portions and performing communications with the imaging controller. The lens controller takes out the information of the optical performance from the memory in response to an instruction from the imaging controller, and transmits the information to the imaging controller through the communicating portions. The imaging controller changes the information size of the image information in accordance with the information of the optical performance from the lens controller.