Optical device and signal processor

摘要

A camera 200 comprises an image pickup element 107 which has imaging pixels performing a photoelectric conversion of an object image formed by a light beam emitted from an image pickup optical system and focus detection pixels performing a photoelectric conversion of two images formed by two divided light beams, a focus detector which obtains first and second pairs of image signals having optical base lengths different from each other from the focus detection pixels, a selector which selects one of the first and second pairs of image signals based on at least one correlation amount of the first and second pairs of image signals, and a calculator which calculates a defocus amount based on the selected pair of image signals.