BACKGROUND

1. Technical Field

A technique of the present disclosure relates to an imaging device, an imaging method, and a program.

2. Related Art

In the related art, an imaging device comprising a zoom tracking unit that executes a zoom tracking control for moving a focus adjustment lens according to the drive of a zoom lens is disclosed (refer to JP2012-255910A). In a case where the drive of the zoom lens is detected while the focus adjustment lens is driven in order to detect a focus state of an optical system, the imaging device stops the drive of the focus adjustment lens and causes the zoom tracking unit to execute the zoom tracking control.

An imaging device comprising a memory that holds data of an imaging range where imaging by focusing using a cam curve of a lens is ensured; and a control unit that moves a focus lens in conjunction with the zoom lens is disclosed (refer to JP2006-162821A). In a case where a focal depth detected by the position of the zoom lens is less than the imaging range at the position of the zoom lens, the imaging device drives the focus lens by an autofocus control using an evaluation value indicating a focusing degree. Further, in a case where the focal depth detected by the position of the zoom lens is greater than the imaging range at the position of the zoom lens, the imaging device drives the focus lens by the cam curve in the data of the imaging range.

SUMMARY

In the imaging device including the zoom lens and the focus lens, in a case where a zoom operation is performed during the execution of the autofocus, the zoom tracking control is performed based on the position of the focus lens during the autofocus, and as a result, focusing accuracy may be reduced in some cases. On the other hand, it is considered that in a case where the zoom operation is performed during the execution of the autofocus, the autofocus is interrupted, the focus lens is returned to the position before the execution of the autofocus, and then the zoom tracking control is performed.

However, in such a case, in order to suppress a decrease in focusing accuracy, the autofocus is executed again after the zoom tracking control is performed, and thus the control time of the imaging device becomes longer.

An embodiment of the invention is made in view of the above circumstances, and is to provide an imaging device, an imaging method, and a program which can suppress a decrease in focusing accuracy while reducing control time of the imaging device.

An imaging device of the present disclosure comprises: an imaging lens having an imaging optical system including a focus lens; an acquisition unit that acquires a focal length of the imaging lens; and a control unit that performs zoom tracking control to change a state of the focus lens according to the focal length acquired by the acquisition unit, in which in a case where a change of the focal length acquired by the acquisition unit is detected, the control unit varies a criterion in the zoom tracking control depending on whether autofocus is being executed or not.

In the imaging device of the present disclosure, in a case where the autofocus is not being executed, the control unit may perform the zoom tracking control based on a current position of the focus lens, and in a case where the autofocus is being executed, the control unit may perform the zoom tracking control based on a position of the focus lens before execution of the autofocus.

In the imaging device of the present disclosure, in a case where the autofocus is being executed, the control unit may change control on the basis of a driving amount of the focus lens at a time of performing the zoom tracking control based on the position of the focus lens before execution of the autofocus.

In the imaging device of the present disclosure, in a case where a change of the focal length acquired by the acquisition unit is detected and the autofocus is being executed, when the driving amount of the focus lens at the time of performing the zoom tracking control based on the position of the focus lens before execution of the autofocus is equal to or less than a threshold value, the control unit may continue the autofocus, and when the driving amount exceeds the threshold value, the control unit may interrupt the autofocus and performs the zoom tracking control based on the position of the focus lens before execution of the autofocus.

In the imaging device of the present disclosure, the threshold value may be a value less than a distance between consecutive positions at a time of deriving an evaluation value of the autofocus while changing the position of the focus lens.

In the imaging device of the present disclosure, in a case where a change of the focal length acquired by the acquisition unit is detected and the autofocus is being executed, when a peak value of an evaluation value of the autofocus has been detected, the control unit may interrupt the autofocus and perform the zoom tracking control based on the position of the focus lens where the evaluation value is the peak value, and when the peak value of the evaluation value has not been detected, the control unit may perform control to continue the autofocus.

In the imaging device of the present disclosure, in a case where a change of the focal length acquired by the acquisition unit is detected and the autofocus is being executed, when a search direction of the autofocus is opposite to a driving direction of the focus lens associated with the zoom tracking control, the control unit may interrupt the autofocus and perform the zoom tracking control based on the position of the focus lens before execution of the autofocus, and when the search direction is the same as the driving direction, the control unit may perform control to continue the autofocus.

In the imaging device of the present disclosure, in a case where a change of the focal length acquired by the acquisition unit is detected, the autofocus is being executed, and the autofocus is continued, the control unit may perform control to perform the autofocus by changing an end position of a search range of the autofocus by the driving amount of the focus lens associated with the zoom tracking control.

In the imaging device of the present disclosure, in a case where a change of the focal length acquired by the acquisition unit is detected and the autofocus is not being executed, the control unit may perform the zoom tracking control based on the current position of the focus lens.

An imaging method of the present disclosure is an imaging method executed by an imaging device comprising an imaging lens having an imaging optical system including a focus lens. The imaging method comprises acquiring a focal length of the imaging lens; and in performing of zoom tracking control to change a state of the focus lens according to the acquired focal length, in a case where a change of the acquired focal length is detected, varying a criterion in the zoom tracking control depending on whether autofocus is being executed or not.

A program of the present disclosure is a program causing a computer of an imaging device comprising an imaging lens having an imaging optical system including a focus lens to execute processing of: acquiring a focal length of the imaging lens; and in performing of zoom tracking control to change a state of the focus lens according to the acquired focal length, in a case where a change of the acquired focal length is detected, varying a criterion in the zoom tracking control depending on whether autofocus is being executed or not.

Further, an imaging device of the present disclosure includes a processor and a memory. The memory stores a command for causing a computer of the imaging device comprising an imaging lens having an imaging optical system including a focus lens to execute processing of: acquiring a focal length of the imaging lens; and in performing of zoom tracking control to change a state of the focus lens according to the acquired focal length, in a case where a change of the acquired focal length is detected, varying a criterion in the zoom tracking control depending on whether autofocus is being executed or not. The processor executes the command.

According to an embodiment of the invention, it is possible to suppress a decrease in focusing accuracy while reducing control time of an imaging device.

