Image capturing apparatus and focusing control method

A focusing control method performed by an image capturing apparatus including an image capturing element configured to capture an image of a subject through an image capturing optical system,

• wherein the image capturing element comprises signal detection units having first signal detection units and second signal detection units, each of the first signal detection units is configured to detect a signal according to one of a pair of light fluxes, said one and the other of the pair of light fluxes having passed through different portions of a pupil area of the image capturing optical system, and each of the second signal detection units is configured to detect a signal according to the other of the pair of light fluxes,
• wherein the focusing control method comprising:
• a focusing control step of performing a focusing control of the image capturing optical system by a phase difference AF method using the detection signals of the first signal detection units and the second signal detection units;
• a matching degree generation step of generating
• a first matching degree which corresponds to a matching degree of two images captured by a first pair using the detection signals of the respective signal detection units of the first pair, wherein the first pairs is a pair of a first signal detection unit group of a plurality of the first signal detection units parallel in a phase difference detection direction by the first signal detection unit and the second signal detection unit and a signal detection unit group of the second signal detection units arranged to be spaced apart by a same distance in one direction with respect to the respective signal detection units of the first signal detection unit group, and
• a second matching degree which corresponds to a matching degree of two images captured by a second pair using the detection signals of the respective signal detection units of the second pair, wherein the second pairs is a pair of a second signal detection unit group of a plurality of the first signal detection units arranged to be spaced apart by a same distance in a same direction with respect to the respective signal detection units of the first signal detection unit group and parallel in the phase difference detection direction and a signal detection unit group of the second signal detection units arranged to be spaced apart by a same distance in another direction different from the one direction with respect to the respective signal detection units of the second signal detection unit group;
• and
• a credibility determination step of determining credibility of the focusing control by the phase difference AF method using the detection signals of the respective signal detection units of each of the first pair and the second pair based on the first matching degree and the second matching degree.