Patent ID: 8488956

Claim:
An apparatus comprising: image pickup unit that includes a first pixel group and a second pixel group, the first pixel group receiving a light beam that passes through a first pupil area of an optical system that forms an object image and the second pixel group receiving a light beam that passes through a second pupil area; correcting unit that corrects a first signal based on an output signal from the first pixel group and a second signal based on an output signal from the second pixel group using correction information with a sampling pitch corresponding to an amount of defocus determined by an amount of relative image displacement between the first signal and the second signal, the sampling pitch being changed when the determined amount of defocus is smaller than a preset threshold; and focus adjusting unit that adjusts a focal state of the optical system based on an amount of defocus determined by an amount of relative displacement between a corrected first signal and a corrected second signal obtained as a result of the correction.