Image-capturing apparatus and control method thereof

An image-capturing apparatus comprising:

• an image sensor including a plurality of pixels arranged in a matrix, the plurality of pixels configured to output a signal by photoelectrically converting a light flux passing through an image-capturing optical system;
• and
• a focus detector configured to perform a focus detection process using an output from the image sensor;
• and
• a controller,
• wherein the image-capturing apparatus has a first focus detection mode and a second focus detection mode,
• wherein in the first focus detection mode, the focus detector performs the focus detection process using a first output from the image sensor, the first output being obtained by controlling a first assist light emitter so as to emit a flash assist light in synchronization with a timing when the image sensor is exposed, and
• wherein in the second focus detection mode, the focus detector performs the focus detection process using a second output from the image sensor, the second output being obtained by controlling a second assist light emitter so as to emit a constant assist light,
• wherein the controller causes the focus detector to perform the focus detection process in the second focus detection mode in a case where a photometric value acquired when the constant assist light is emitted from the second assist light emitter has a predetermined change with respect to a photometric value acquired before the constant assist light is emitted, and to perform the focus detection process in the first focus detection mode in a case where the photometric value acquired when the constant assist light is emitted does not have the predetermined change with respect to the photometric value acquired before the constant assist light is emitted.