Image pickup apparatus and control method thereof

An image pickup apparatus comprising:

• an image sensor including plural pixels, each pixel being constituted by (a) a microlens causing light fluxes from mutually different areas in an exit pupil of an image capturing optical system to form two object images and (b) two photoelectric conversion portions photoelectrically converting the two object images;
• a signal reader configured to perform a first reading operation that adds signals from the two photoelectric conversion portions to read the added signal as a pixel signal and a second reading operation that independently reads the signal from each of the two photoelectric conversion portions as the pixel signal;
• and
• a phase difference detector configured to detect a phase difference between the two object images by using the pixel signal read by the second reading operation,
• wherein the signal reader performs, when the phase difference detector detects the phase difference, the second reading operation only on the pixels arranged at a predetermined arrangement cycle among the plural pixels.

A method of controlling an image pickup apparatus including an image sensor including plural pixels, each pixel being constituted by (a) a microlens causing light fluxes from mutually different areas in an exit pupil of an image capturing optical system to form two object images and (b) two photoelectric conversion portions photoelectrically converting the two object images, the method comprising:

• a signal reading step of performing a first reading operation that adds signals from the two photoelectric conversion portions to read the added signal as a pixel signal and a second reading operation that independently reads the signal from each of the two photoelectric conversion portions as the pixel signal;
• and
• a phase difference detecting step of detecting a phase difference between the two object images by using the pixel signal read by the second reading operation,
• wherein the signal reading step performs, when the phase difference detecting step detects the phase difference, the second reading operation only on the pixels arranged at a predetermined arrangement cycle among the plural pixels.