Image capturing apparatus and control method thereof

An image capturing apparatus comprising:

• an image sensor having focus detection pixels that photoelectrically convert each of a pair of light fluxes that pass through different exit pupil areas of an imaging optical system and output a focus detection signal, and image forming pixels;
• a calculation unit configured to calculate a first charge accumulation period for the image forming pixels, a second charge accumulation period for the focus detection pixels, and a third charge accumulation period for a predetermined number of rows that do not contain the focus detection pixels;
• a control unit configured to read out the focus detection signal accumulated in the focus detection pixels and an image forming signal accumulated in the image forming pixels;
• a first focus control unit configured to perform phase difference focus control process based on the focus detection signal read out after accumulated for the second charge accumulation period from the focus detection pixels;
• and
• a second focus control unit configured to carry out a focus detection process based on a high-frequency component of an image signal obtained from the image forming pixels in a row driven with the third charge accumulation period, while moving the focus control mechanism,
• wherein the control unit reads out the focus detection signal and the image forming signal, and sets a readout rate of the focus detection signal to be lower than a readout rate of the image forming signal, and
• wherein the control unit drives the predetermined number of rows with the third charge accumulation period while moving a focus control mechanism.