Image capturing apparatus and control method therefor and storage medium

A control method for an image capturing apparatus, the method comprising:

• by a light receiving sensor including two-dimensionally arranged pixels, photoelectrically converting a pair of object images having passed through a first pupil region and a second pupil region into which a pupil region of an image capturing lens is divided in a first direction and outputting a first image signal and a second image signal, each of the first image signal and the second image signal corresponding to a respective object image of the pair of object images;
• calculating a first phase difference between the first image signal and the second image signal in the first direction and a second phase difference between the first image signal and the second image signal in a second direction orthogonal to the first direction;
• calculating a first focus detection result based on the first phase difference;
• and
• determining presence or absence of heat haze based on the second phase difference.

A non-transitory computer readable storage medium storing a program for causing a computer to execute each of the steps of a control method for an image capturing apparatus, the method comprising:

• by a light receiving sensor including two-dimensionally arranged pixels, photoelectrically converting a pair of object images having passed through a first pupil region and a second pupil region into which a pupil region of an image capturing lens is divided in a first direction and outputting a first image signal and a second image signal, each of the first image signal and the second image signal corresponding to a respective object image of the pair of object images;
• calculating a first phase difference between the first image signal and the second image signal in the first direction and a second phase difference between the first image signal and the second image signal in a second direction orthogonal to the first direction;
• calculating a first focus detection result based on the first phase difference;
• and
• determining presence or absence of heat haze based on the second phase difference.