Patent ID: 7863550

Claim:
A focus detection device, comprising: an image shift detection unit that detects a relative shift amount of a pair of images formed by a pair of light fluxes having passed through an optical system; a conversion unit that converts the shift amount to a defocus amount based upon dimensional information of an exit pupil corresponding to an aperture restricting light flux in the optical system and distance information of the exit pupil indicating distance to the exit pupil from a predetermined imaging plane of the optical system; a gravitational center information output unit that outputs a center position of gravity of at least one of the light fluxes in the pair of light fluxes included in the light flux restricted by the exit pupil on a plane on which the exit pupil is set, based upon the dimensional information and the distance information of the exit pupil; a detection point positional information output unit that outputs positional information indicating a position of the detection point at which the defocus amount is detected; and a light quantity distribution information output unit that outputs light quantity distribution information indicating light quantity distributions in at least one of the light fluxes on the plane on which the exit pupil is set, wherein: the conversion unit converts the shift amount to the defocus amount based upon the distance information of the exit pupil and the center position of gravity, and the gravitational center information output unit outputs a center position of gravity of at least one of the light fluxes in the pair of the light fluxes included in the light flux restricted by the exit pupil on a plane on which the exit pupil is set, based upon the distance information of the exit pupil, the dimensional information of the exit pupil, the positional information, and the light quantity distribution information.