Focus detection apparatus, focus control apparatus, image-capturing apparatus and focus detection method

A focus control apparatus comprising circuitry which function as:

• a focus detection apparatus;
• and
• a controller configured to control driving of a focus lens depending on focus detection information acquired by the focus detection apparatus,
• wherein the focus detection apparatus comprises:
• a producer configured (a) to acquire paired phase difference image signals that are produced through photoelectric conversion of an object image formed by an optical system including the focus lens and that have therebetween a phase difference corresponding to a focus state of the object image, and (b) to produce focus detection information using the phase difference acquired from the paired phase difference image signals;
• and
• an acquirer configured to acquire a feature value relating to a correlation value between the paired phase difference image signals,
• wherein the producer is configured to acquire the phase difference depending on a result of comparison between the feature values acquired before and after driving of the focus lens.

An image-capturing apparatus comprising:

• an image sensor configured to capture an object image;
• and
• a focus control apparatus,
• wherein the focus control apparatus comprises circuitry which function as:
• a focus detection apparatus;
• and
• a controller configured to control driving of
• a focus lens depending on focus detection information acquired by the focus detection apparatus,
• wherein the focus detection apparatus comprises:
• a producer configured (a) to acquire paired phase difference image signals that are produced through photoelectric conversion of an object image formed by an optical system including the focus lens and that have therebetween a phase difference corresponding to a focus state of the object image, and (b) to produce focus detection information using the phase difference acquired from the paired phase difference image signals;
• and
• an acquirer configured to acquire a feature value relating to a correlation value between the paired phase difference image signals,
• wherein the producer is configured to acquire the phase difference depending on a result of comparison between the feature values acquired before and after driving of the focus lens.

A focus detection method comprising the steps of:

• acquiring paired phase difference image signals that are produced through photoelectric conversion of an object image formed by an optical system including the focus lens and that have therebetween a phase difference corresponding to a focus state of the object image;
• producing focus detection information using the phase difference acquired from the paired phase difference image signals;
• and
• acquiring a feature value relating to a correlation value between the paired phase difference image signals,
• wherein the method acquires the phase difference depending on a result of comparison between the feature values acquired before and after driving of the focus lens.

A non-transitory computer-readable storage medium for storing a computer program to cause a computer to execute a focus detection process,

• the focus detection process comprising:
• acquiring paired phase difference image signals that are produced through photoelectric conversion of an object image formed by an optical system including the focus lens and that have therebetween a phase difference corresponding to a focus state of the object image;
• producing focus detection information using the phase difference acquired from the paired phase difference image signals;
• and
• acquiring a feature value relating to a correlation value between the paired phase difference image signals,
• wherein the process acquires the phase difference depending on a result of comparison between the feature values acquired before and after driving of the focus lens.