Imaging device, focusing control method, and focusing control program

An imaging device comprising:

• an imaging element that images a subject through an imaging optical system comprising a focus lens;
• first signal detection parts that detect signals corresponding to one of a pair of luminous fluxes passed through different portions of a pupil area of the imaging optical system;
• second signal detection parts that detect signals corresponding to other one of the pair of luminous fluxes;
• a focusing controller that selectively performs focusing control by a phase difference AF method using a result of a correlation operation of detection signals of the first signal detection parts and detection signals of the second signal detection parts or focusing control by a contrast AF method using contrast of a captured image captured by the imaging element in a mode in which focusing control for focusing on a main subject by driving the focus lens is continuously performed multiple times;
• and
• a detection unit that detects a direction of gravity,
• wherein the focusing controller performs the focusing control by the contrast AF method in a case where a state in which a degree of reliability of the focusing control by the phase difference AF method is equal to or less than a threshold value persists N times, N being a natural number of 2 or more, while the focusing control by the phase difference AF method is continuously performed,
• the focusing controller sets a first subject area, which is to be in focus in a case where the focusing control by the contrast AF method is performed, to be an area which includes a second subject area to be in focus in the focusing control by the phase difference AF method and is larger than the second subject area,
• the focusing controller sets a difference between a width of the second subject area in a first direction and a width of the first subject area in the first direction to be greater than a difference between a width of the second subject area in a second direction perpendicular to the first direction and a width of the first subject area in the second direction, and
• the focusing controller sets the first subject area with a direction perpendicular to the direction of gravity as the first direction.

A focusing control method comprising:

• a focusing control step of selectively performing focusing control by a phase difference AF method using a result of a correlation operation of detection signals of first signal detection parts that detect signals corresponding to one of a pair of luminous fluxes passed through different portions of a pupil area of an imaging optical system and detection signals of second signal detection parts that detect signals corresponding to other one of the pair of luminous fluxes or focusing control by a contrast AF method using contrast of a captured image captured by an imaging element that images a subject through the imaging optical system, in a case where focusing control for focusing on a main subject by driving a focus lens of the imaging optical system including the focus lens is continuously performed multiple times,
• wherein, in the focusing control step, the focusing control by the contrast AF method is performed in a case where a state in which a degree of reliability of the focusing control by the phase difference AF method is equal to or less than a threshold value persists N times, N being a natural number of 2 or more, while the focusing control by the phase difference AF method is continuously performed, and
• in the focusing control step, the focusing control by the contrast AF method is performed in a case where the state in which the degree of reliability is equal to or less than the threshold value persists less than N times and an elapsed time after the degree of reliability is equal to or less than the threshold value reaches a time threshold value while the focusing control by the phase difference AF method is continuously performed.

A focusing control method comprising:

• a focusing control step of selectively performing focusing control by a phase difference AF method using a result of a correlation operation of detection signals of first signal detection parts that detect signals corresponding to one of a pair of luminous fluxes passed through different portions of a pupil area of an imaging optical system and detection signals of second signal detection parts that detect signals corresponding to other one of the pair of luminous fluxes or focusing control by a contrast AF method using contrast of a captured image captured by an imaging element that images a subject through the imaging optical system, in a case where focusing control for focusing on a main subject by driving a focus lens of the imaging optical system including the focus lens is continuously performed multiple times;
• and
• a detection step of detecting a direction of gravity,
• wherein, in the focusing control step, the focusing control by the contrast AF method is performed in a case where a state in which a degree of reliability of the focusing control by the phase difference AF method is equal to or less than a threshold value persists N times, N being a natural number of 2 or more, while the focusing control by the phase difference AF method is continuously performed,
• in the focusing control step, a first subject area to be in focus in a case where the focusing control by the contrast AF method is performed is set to be an area which includes a second subject area to be in focus in the focusing control by the phase difference AF method and is larger than the second subject area,
• in the focusing control step, a difference between a width of the second subject area in a first direction and a width of the first subject area in the first direction is set to be greater than a difference between a width of the second subject area in a second direction perpendicular to the first direction and a width of the first subject area in the second direction, and
• in the focusing control step, the first subject area is set with a direction perpendicular to the direction of gravity as the first direction.

A computer readable medium storing a focusing control program causing a computer to perform:

• a focusing control step of selectively performing focusing control by a phase difference AF method using a result of a correlation operation of detection signals of first signal detection parts that detect signals corresponding to one of a pair of luminous fluxes passed through different portions of a pupil area of an imaging optical system and detection signals of second signal detection parts that detect signals corresponding to other one of the pair of luminous fluxes or focusing control by a contrast AF method using contrast of a captured image captured by an imaging element that images a subject through the imaging optical system, in a case where focusing control for focusing on a main subject by driving a focus lens of the imaging optical system including the focus lens is continuously performed multiple times,
• wherein, in the focusing control step, the focusing control by the contrast AF method is performed in a case where a state in which a degree of reliability of the focusing control by the phase difference AF method is equal to or less than a threshold value persists N times, N being a natural number of 2 or more, while the focusing control by the phase difference AF method is continuously performed, and
• in the focusing control step, the focusing control by the contrast AF method is performed in a case where the state in which the degree of reliability is equal to or less than the threshold value persists less than N times and an elapsed time after the degree of reliability is equal to or less than the threshold value reaches a time threshold value while the focusing control by the phase difference AF method is continuously performed.

A computer readable medium storing a focusing control program causing a computer to perform:

• a focusing control step of selectively performing focusing control by a phase difference AF method using a result of a correlation operation of detection signals of first signal detection parts that detect signals corresponding to one of a pair of luminous fluxes passed through different portions of a pupil area of an imaging optical system and detection signals of second signal detection parts that detect signals corresponding to other one of the pair of luminous fluxes or focusing control by a contrast AF method using contrast of a captured image captured by an imaging element that images a subject through the imaging optical system, in a case where focusing control for focusing on a main subject by driving a focus lens of the imaging optical system including the focus lens is continuously performed multiple times;
• and
• a detection step of detecting a direction of gravity,
• wherein, in the focusing control step, the focusing control by the contrast AF method is performed in a case where a state in which a degree of reliability of the focusing control by the phase difference AF method is equal to or less than a threshold value persists N times, N being a natural number of 2 or more, while the focusing control by the phase difference AF method is continuously performed,
• in the focusing control step, a first subject area to be in focus in a case where the focusing control by the contrast AF method is performed is set to be an area which includes a second subject area to be in focus in the focusing control by the phase difference AF method and is larger than the second subject area,
• in the focusing control step, a difference between a width of the second subject area in a first direction and a width of the first subject area in the first direction is set to be greater than a difference between a width of the second subject area in a second direction perpendicular to the first direction and a width of the first subject area in the second direction, and
• in the focusing control step, the first subject area is set with a direction perpendicular to the direction of gravity as the first direction.