Image capturing apparatus and control method thereof, and storage medium

A non-transitory computer-readable storage medium storing a program for causing a computer to execute the steps of a method of controlling an image capturing apparatus including an image sensor in which pixels are arrayed two-dimensionally, each of the pixels including a plurality of photoelectric conversion elements for a single microlens, the method comprising:

• switching between carrying out a first readout operation of reading out, from the image sensor and at a first framerate, signals from photoelectric conversion elements corresponding to a first number of pupil areas among a plurality of pupil areas of an imaging optical system and a signal obtained by adding together signals from the photoelectric conversion elements corresponding to all of the pupil areas among the plurality of pupil areas of the imaging optical system, and a second readout operation of reading out, from the image sensor and at a second framerate, signals from photoelectric conversion elements corresponding to a second number, different from the first number, of pupil areas among the plurality of pupil areas of the imaging optical system and a signal obtained by adding together signals from the photoelectric conversion elements corresponding to all of the pupil areas among the plurality of pupil areas of the imaging optical system;
• and
• controlling whether to cause the first readout operation or the second readout operation to be carried out in accordance with a status of the image capturing apparatus.