Focus detection apparatus, focus control apparatus, image capturing apparatus, focus detection method, and storage medium

A focus control apparatus comprising a focus detection apparatus configured to detect a focus state of an image capturing optical system by using a phase difference between a pair of phase difference image signals obtained by photoelectrically converting, through a focus detection element, a pair of object images which are formed by dividing a light flux from an image capturing optical system, the focus detection element including a plurality of photoelectric converters that two-dimensionally arranged in a first direction in which a distance between the pair of object images changes according to the focus state, and a second direction orthogonal to the first direction;

• and
• a controller configured to control driving of a focus lens in the image capturing optical system based on the phase difference,
• wherein the focus detection apparatus includes:
• a first acquirer configured to acquire a first distance as the distance in the first direction based on the pair of phase difference image signals;
• a second acquirer configured to acquire a correction value corresponding to a second distance as the distance between the pair of object images in the second direction;
• and
• a calculator configured to calculate the phase difference using the first distance and the correction value.

An image capturing apparatus comprising:

• an image sensor configured to capture an object image;
• and
• a focus control apparatus that includes:
• a focus detection apparatus configured to detect a focus state of an image capturing optical system by using a phase difference between a pair of phase difference image signals obtained by photoelectrically converting, through a focus detection element, a pair of object images which are formed by dividing a light flux from an image capturing optical system, the focus detection element including a plurality of photoelectric converters that are two-dimensionally arranged in a first direction in which a distance between the pair of object images changes according to the focus state, and a second direction orthogonal to the first direction;
• and
• a controller configured to control driving of a focus lens in the image capturing optical system based on the phase difference, and
• wherein the focus detection apparatus includes:
• a first acquirer configured to acquire a first distance as the distance in the first direction based on the pair of phase difference image signals;
• a second acquirer configured to acquire a correction value corresponding to a second distance as the distance between the pair of object images in the second direction;
• and
• a calculator configured to calculate the phase difference using the first distance and the correction value.

A focus detection method configured to detect a focus state of an image capturing optical system by using a phase difference between a pair of phase difference image signals obtained by photoelectrically converting, through a focus detection element, a pair of object images which are formed by dividing a light flux from an image capturing optical system, the focus detection element including a plurality of photoelectric converters that are two-dimensionally arranged in a first direction in which a distance between the pair of object images changes according to the focus state, and a second direction orthogonal to the first direction, the focus detection method comprising the steps of:

• acquiring a first distance as the distance in the first direction based on the pair of phase difference image signals;
• acquiring a correction value corresponding to a second distance as the distance between the pair of object images in the second direction;
• and
• calculating the phase difference using the first distance and the correction value.

A computer-readable storage medium for storing a program that enables a computer to execute a focus detection method configured to detect a focus state of an image capturing optical system by using a phase difference between a pair of phase difference image signals obtained by photoelectrically converting, through a focus detection element, a pair of object images which are formed by dividing a light flux from an image capturing optical system, the focus detection element including a plurality of photoelectric converters that are two-dimensionally arranged in a first direction in which a distance between the pair of object images changes according to the focus state, and a second direction orthogonal to the first direction, the focus detection method comprising the steps of:

• acquiring a first distance as the distance in the first direction based on the pair of phase difference image signals;
• acquiring a correction value corresponding to a second distance as the distance between the pair of object images in the second direction;
• and
• calculating the phase difference using the first distance and the correction value.

A focus detection apparatus configured to detect a focus state of an image capturing optical system by photoelectrically converting, through a focus detection element, a pair of object images which are formed by a focus detection optical system configured to divide a light flux from the image capturing optical system, the focus detection element including a plurality of photoelectric converters that are two-dimensionally arranged in a first direction and a second direction orthogonal to the first direction, the focus detection apparatus comprising:

• a signal generator configured to generate a pair of phase difference image signals by using an output from the focus detection element;
• and
• a calculator configured to calculate a phase difference in the first direction between the pair of the phase difference image signals and to obtain the focus state based on the phase difference,
• wherein the signal generator corrects the pair of phase difference image signals about a shift of at least one of a shape and a position in the second direction of the pair of object images.