Focus detection apparatus and focus detection method

A focus detection apparatus comprising:

• an image sensor that includes a plurality of focus detection pixels and that images a subject via an imaging optical system;
• a correction value calculation circuit that calculates a correction value based on an optical state, the correction value being used to correct pixel signals output from the focus detection pixels, the optical state being associated with light fluxes from the subject incident on the focus detection pixels;
• a luminance correction circuit that corrects the pixel signals output from the focus detection pixels using the correction value;
• and
• a focus detection circuit that performs focus detection based on the corrected pixel signals,
• wherein the luminance correction circuit calculates, when imaging for still image capturing is performed in a continuous-exposure mode, the correction value based on the optical state during driving of a focus lens and an aperture immediately before the imaging for still image capturing by the image sensor, and calculates, when imaging for focus detection is performed in the continuous-exposure mode, the correction value based on the optical state during reading of the pixel signals acquired in a previous imaging for still image capturing, and
• the correction value calculation circuit performs the correction using the correction value simultaneously with the reading of the pixel signals from the focus detection pixels subsequent to the imaging for the still image capturing and the imaging for the focus detection.