Focus adjustment apparatus, focus adjustment method and program, and imaging apparatus

A focus adjustment apparatus for performing a focus adjustment of an object by using pixel signals obtained by photoelectrically converting object light which passes through different pupil areas of a focusing optical system for forming an optical image of the object, comprising:

• at least one processor, configured to function as:
• an obtaining unit configured to obtain the pixel signals;
• a signal generation unit configured to generate a plurality of focus detection signals corresponding to the different pupil areas by using the pixel signals;
• a first focus detection unit configured to detect a first defocus amount on the basis of a correlation amount which is generated from the plurality of focus detection signals;
• a second focus detection unit configured to detect a second defocus amount on the basis of a contrast evaluation value which is generated from the plurality of focus detection signals;
• and
• a control unit configured to control the first focus detection unit and the second focus detection unit and control the focus adjustment in accordance with a focus adjustment state of the object on the basis of one of the first defocus amount and the second defocus amount.

An imaging apparatus comprising:

• a focusing optical system that includes one or more optical elements and is configured to form an optical image of an object;
• an image sensor configured to receive, through a pupil division unit, object light which passes through different pupil areas of the focusing optical system and photoelectrically convert the received object light, thereby generating pixel signals corresponding to the object light which passes through the different pupil areas;
• and
• at least one processor, configured to function as:
• a signal generation unit configured to generate a plurality of focus detection signals corresponding to the different pupil areas by using the pixel signals;
• a first focus detection unit configured to detect a first defocus amount on the basis of an image shift amount of the plurality of focus detection signals;
• a second focus detection unit configured to detect a second defocus amount on the basis of a shift amount of the focus detection signal for generating a refocus signal from the plurality of focus detection signals;
• and
• a control unit configured to control the first focus detection unit and the second focus detection unit and controls the driving of the focusing optical system in accordance with a focus adjustment state of the object on the basis of one of the first defocus amount and the second defocus amount.

A focus detection method comprising:

• an obtaining step of obtaining first and second image signals having a mutual parallax;
• a combining step of generating a combination signal obtained by combining the first and second image signals at least one of which is shifted by a predetermined step, wherein the shift and the generation of the combination signal in the combining step are executed for a plurality of predetermined steps and a plurality of combination signals are generated;
• a calculation step of calculating a contrast evaluation value from the plurality of combination signals;
• and
• a focus detection step of detecting a defocus amount on the basis of the contrast evaluation value and a shift amount of the shift.

A non-transitory computer-readable storage medium storing a program for controlling a focus detection apparatus, wherein the program comprises code for causing a computer to function as:

• an obtaining unit configured to obtain first and second image signals having a mutual parallax;
• a combination unit configured to generate a combination signal obtained by combining the first and second image signals at least one of which is shifted by a predetermined step, wherein the shift and the generation of the combination signal which are performed by the combination unit are executed for a plurality of predetermined steps and a plurality of combination signals are generated;
• a calculation unit configured to calculate a contrast evaluation value from the plurality of combination signals;
• and
• a focus detection unit configured to detect a defocus amount on the basis of the contrast evaluation value and a shift amount of the shift.

A focus adjustment method of performing a focus adjustment of an object by using pixel signals obtained by photoelectrically converting object light which passes through different pupil areas of a focusing optical system for forming an optical image of the object, comprising:

• an obtaining step of obtaining the pixel signals;
• a signal generation step of generating a plurality of focus detection signals corresponding to the different pupil areas by using the pixel signals;
• a first focus detection step of detecting a first defocus amount on the basis of an image shift amount of the plurality of focus detection signals;
• a second focus detection step of detecting a second defocus amount on the basis of a shift amount of a focus detection signal to generate a refocus signal from the plurality of focus detection signals;
• and
• a control step of controlling the first focus detection step and the second focus detection step and controlling the focus adjustment in accordance with a focus adjustment state of the object on the basis of one of the first defocus amount and the second defocus amount.

A non-transitory computer-readable storage medium storing a program for controlling a focus adjustment apparatus for performing a focus adjustment of an object by using pixel signals obtained by photoelectrically converting object light which passes through different pupil areas of a focusing optical system for forming an optical image of the object, wherein the program comprises code for causing a computer to function as:

• an obtaining unit configured to obtain the pixel signals;
• a signal generation unit configured to generate a plurality of focus detection signals corresponding to the different pupil areas by using the pixel signals;
• a first focus detection unit configured to detect a first defocus amount on the basis of an image shift amount of the plurality of focus detection signals;
• a second focus detection unit configured to detect a second defocus amount on the basis of a shift amount of a focus detection signal to generate a refocus signal from the plurality of focus detection signals;
• and
• a control unit configured to control the first focus detection unit and the second focus detection unit and control the focus adjustment in accordance with a focus adjustment state of the object on the basis of one of the first defocus amount and the second defocus amount.