Patent ID: 8823851

Claim:
An image capturing apparatus comprising: an optical system configured to form an image of a subject; an image sensor that includes a plurality of pixels each having a plurality of photoelectric converters and that is capable of outputting image signals independently from the plurality of photoelectric converters, the plurality of photoelectric converters respectively receiving a plurality of luminous fluxes that have passed through areas of different exit pupils of the optical system; a driving unit configured to control driving of the image sensor; a focus detection unit configured to conduct focus detection using a phase difference method based on the image signals independently output from the plurality of photoelectric converters in the image sensor; and an addition unit configured to add the image signals independently output from the plurality of photoelectric converters in the image sensor on a per-pixel basis, wherein in each pixel, the plurality of photoelectric converters are divided into a plurality of groups each including at least two photoelectric converters, a charge accumulation period for one group is delayed from and partially overlaps a charge accumulation period for another, the driving unit drives the image sensor with first driving whereby image signals are read from the plurality of groups, one group in each predetermined period, and the focus detection unit detects a focus state based on the image signals read through the first driving.