Patent ID: 8644698

Claim:
An apparatus that detects a focusing state of an optical system based on a detection area of a photoelectric conversion element including a plurality of pixels receiving a light flux from a subject space, the apparatus comprising: a selection unit configured to select, from outputs of the detection areas, an output of the detection area for controlling the optical system based on a reliability value of the output, wherein detection areas are related to a plurality of AF frames respectively; and a controller configured to control a drive of the optical system based on the selected output, wherein the selection unit makes it difficult to select, from the plurality of detection areas, an output having a part overlapping with an AF frame, on a primary imaging surface, compared to an output not having the overlapping part, and wherein the reliability value is updated in a case where the output has the part overlapping with the AF frame and the reliability value is not updated in a case where the output does not have the overlapping part.