Image capturing apparatus having focus detection pixels producing a focus signal with reduced noise

Abstract

An image capturing apparatus comprises: an image sensor having image forming pixels for receiving light that has passed through an entire pupil area of an imaging lens which forms an object image, and focus detection pixels, which are arranged discretely among the image forming pixels, for receiving light that has passed through part of the pupil area of the imaging lens; a detection unit configured to detect an edge direction of an object based on an image signal acquired by the image sensor; an averaging unit configured to average image signals, while shifting a phase of the image signals, which are acquired respectively from each of the focus detection pixels, based on the edge direction detected by the detection unit; and a calculation unit configured to calculate a defocus amount of the imaging lens using the image signal averaged by the averaging unit.