JP2008129255A - Imaging apparatus, imaging method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of an image, resulting from a wobbling mode used for automatic focus. <P>SOLUTION: A movement determination section 41 detects a panning operation, tilting operation, or zooming operation performed by a user. An evaluation value acquisition section 42 accumulates, after the removal of noise, evaluation values, indicating the degree of focus, for only a predetermined period, and calculates, based on the accumulated evaluation values, an amount of variation in far-to-near evaluation value and an amount of variation in near-to-far evaluation value. A field depth computing section 43 computes the depth of field. A wobbling breadth determination section 44 determines, based on the amount of variation in far-to-near evaluation value and the amount of variation in near-to-far evaluation value, whether a wobbling breadth needs to be restrained or not. If restraint is not required, the wobbling breadth is determined so as to correspond to about 1/2 of the depth of field. If restraint is required, it is determined so as to correspond to about 1/4 of the depth of field. An AF control section 45 is wobbled with the determined wobbling width. The present invention can be used in a video camera. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image pickup apparatus, an image pickup method, and a program, and more particularly, to an image pickup apparatus, an image pickup method, and a program suitable for use in focusing with an autofocus function.

  The autofocus function employed in video cameras and still cameras is roughly classified into an active method and a passive method.

  In the active method, the distance from the camera to the subject is detected based on the time until the subject is irradiated with infrared rays or the like and the reflected wave is received. Based on the distance from the camera to the subject, the focus is controlled, that is, the focus lens is moved to adjust the focus.

  In the passive method, distance measurement is performed using an image signal of a captured subject. One example is a method called a contrast extraction method.

  In the contrast extraction method, focus control is performed based on the sharpness of a subject in an image signal obtained by an image sensor that images the subject.

  That is, in the contrast extraction method, the frequency component of the edge portion of the image signal obtained by the image sensor, that is, the high frequency component is extracted, and the value corresponding to the high frequency component is used as the evaluation value indicating the degree of focusing. The focus is controlled so that the evaluation value is maximized (see, for example, Patent Document 1).

  The focus control operation based on the evaluation value includes a hill-climbing mode and a wobbling mode.

  In the hill-climbing mode, for example, based on several (plural) evaluation values obtained so far, the focus lens is in the two directions of the front side and the back side (subject side) in the optical axis direction. The evaluation value is moved in one direction to increase. If the evaluation value decreases without increasing, it is determined that the focus has been brought into focus at the position where the previous evaluation value was obtained, and the focus lens is stopped at that position.

  That is, for example, if the camera and the subject are not moving, the evaluation value, which is a value corresponding to the high frequency component of the image data obtained by the image sensor, changes so smoothly only by moving the focus lens. In the hill-climbing method, the movement direction of the focus lens in which the evaluation value increases is recognized from the plurality of evaluation values, and the focus lens is moved in the movement direction. Then, when the evaluation value reaches the maximum, the movement of the focus lens is stopped.

  In the wobbling mode, it is used when finely adjusting the position of the focus lens. The focus lens is wobbling in the optical axis direction and stopped at a position where the evaluation value is maximized (see, for example, Patent Document 2). .

  The amplitude for wobbling the focus lens (hereinafter, appropriately referred to as the wobbling width) is usually fixed to a width corresponding to about ½ of the depth of field.

  Here, the depth of field refers to the distance (range) between the near side and the far side in the optical axis direction at which the image data captured by the camera appears to be in focus. That is, when the focus lens is at a certain position, the position of the subject that is in focus exists strictly on one plane orthogonal to the optical axis, but image data captured by the camera. , There is a range that appears to be in focus on the near side and the far side of the plane, and the range from the nearest position to the farthest position of the range is the depth of field. is called. The depth of field is determined by the aperture of the camera, the focus lens position, the zoom lens position, the pixel size of the image sensor, and the like.

JP 7-87377 A JP 2005-277765 A

  By the way, in recent years, high-definition video has been promoted, and video cameras tend to have high precision and a high depth of field by reducing the depth of field of the lens system.

  As described above, when the focus lens is controlled by the wobbling mode due to the high accuracy of the image and the shallow depth of field of the lens system, for example, several times the depth of field in the image. If there is a wide variety of subjects in the range, the background where the focus was blurred until then suddenly becomes sharp, the focus of the clear subject suddenly becomes blurred, For example, the light of a high subject is diffused, and the image is deteriorated so that the user can visually recognize the control of the focus lens in the wobbling mode.

  The present invention has been made in view of such a situation, and is intended to prevent image degradation caused by a wobbling mode during autofocus.

  An imaging apparatus according to one aspect of the present invention calculates an evaluation value indicating a degree of focusing based on the captured image signal in an imaging apparatus having an autofocus function that captures an image signal of a subject. Means, focus control means for wobbling a focus lens with a predetermined wobbling width based on the evaluation value, and focusing on the subject, and the focus lens obtained when the focus lens is moved with an initial value of the wobbling width And a wobbling width determining means for limiting the wobbling width from the initial value based on a history of changes in evaluation values.

  The wobbling width determining means is configured to set the wobbling width to about a half of the depth of field based on a history of change in the evaluation value obtained when the focus lens is moved with an initial value of the wobbling width. Can be limited to a width corresponding to about ¼ of the depth of field.

  The imaging apparatus according to one aspect of the present invention may further include a detection unit that detects at least one of a zooming operation, a panning operation, and a tilting operation by a user, and the wobbling width determination unit includes: When at least one of the zooming operation, the panning operation, and the tilting operation is detected by the detection unit, the limitation of the wobbling width is stopped and the wobbling width is determined as an initial value. be able to.

  An imaging method according to an aspect of the present invention is an imaging method of an imaging apparatus having an autofocus function for imaging an image signal of a subject, and an evaluation value indicating a degree of focusing is obtained based on the captured image signal. A calculation step of calculating, a focus control step of wobbling a focus lens with a predetermined wobbling width based on the evaluation value, and focusing on the subject; and when the focus lens is moved with an initial value of the wobbling width And a wobbling width determination step of limiting the wobbling width from the initial value based on the obtained history of changes in the evaluation value.

  A program according to one aspect of the present invention is a program for controlling an imaging apparatus having an autofocus function that captures an image signal of a subject, and indicates a degree of focusing based on the captured image signal. A calculation step for calculating an evaluation value, a focus control step for causing the focus lens to focus on the subject by wobbling the focus lens with a predetermined wobbling width based on the evaluation value, and moving the focus lens with an initial value of the wobbling width The computer of the imaging apparatus is caused to execute processing including the wobbling width determination step of limiting the wobbling width from the initial value based on the history of the change amount of the evaluation value obtained at the time.

In one aspect of the invention,
Based on the captured image signal, an evaluation value indicating the degree of focusing is calculated. Based on the calculated evaluation value, the focus lens is wobbled with a predetermined wobbling width and focused on the subject. Note that the wobbling width is limited from the initial value based on the history of the evaluation value change obtained when the focus lens is moved at the initial value of the wobbling width.

  According to one aspect of the present invention, it is possible to suppress image degradation caused by a wobbling mode during autofocus.

  Embodiments of the present invention will be described below. Correspondences between constituent elements of the present invention and the embodiments described in the specification or the drawings are exemplified as follows. This description is intended to confirm that the embodiments supporting the present invention are described in the specification or the drawings. Therefore, even if there is an embodiment which is described in the specification or the drawings but is not described here as an embodiment corresponding to the constituent elements of the present invention, that is not the case. It does not mean that the form does not correspond to the constituent requirements. Conversely, even if an embodiment is described here as corresponding to a configuration requirement, that means that the embodiment does not correspond to a configuration requirement other than the configuration requirement. It's not something to do.

  An imaging apparatus according to an aspect of the present invention (for example, the imaging apparatus 1 in FIG. 1) is an imaging apparatus having an autofocus function that captures an image signal of a subject, and is focused based on the captured image signal. And a focus control unit (for example, the AF unit 20 in FIG. 1) that calculates an evaluation value, and a focus control unit that causes the focus lens to wobble with a predetermined wobbling width based on the evaluation value ( For example, the wobbling width is set to be less than the initial value based on the history of the change amount of the evaluation value obtained when the AF control unit 45) of FIG. 2 and the focus lens are moved by the initial value of the wobbling width. The wobbling width determining means for limiting (for example, the wobbling width determining unit 44 in FIG. 2).

  The imaging apparatus according to one aspect of the present invention further includes detection means (for example, the operation determination unit 41 in FIG. 2) that detects at least one of a zooming operation, a panning operation, and a tilting operation by a user.

  An imaging method and a program according to an aspect of the present invention include a calculation step (for example, step S3 in FIG. 3) for calculating an evaluation value indicating a degree of focusing based on the captured image signal, and the evaluation value. Based on a focus control step (for example, step S10 in FIG. 3) in which the focus lens is wobbled with a predetermined wobbling width to focus on the subject, and obtained when the focus lens is moved by the initial value of the wobbling width. And a wobbling width determination step (for example, step S7 in FIG. 3) for limiting the wobbling width from the initial value based on a history of the change amount of the evaluation value.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 shows a configuration example of an imaging apparatus according to an embodiment of the present invention. This imaging device 1 has an autofocus function, and controls the focus lens mainly in a hill-climbing mode, and transitions to a wobbling mode at the time of fine adjustment. While the autofocus function is performed in the wobbling mode, the wobbling width is reduced to 1 of a narrower depth of field from a width corresponding to about 1/2 of the normal depth of field according to the situation. By limiting to a width corresponding to about / 4, image degradation due to the wobbling mode is suppressed.

  The imaging apparatus 1 mainly includes a control unit 11 that controls the entire imaging apparatus 1, an operation input unit 14 that receives a user's operation, a focus lens, a zoom lens, and a diaphragm that focus an optical image of a subject (all not shown). An image sensor 18 that generates an image signal corresponding to an optical image, an image signal processing unit 19 that performs predetermined image signal processing on the generated image signal, and auto-focusing AF unit 20 for generating an evaluation value indicating the degree of in-focus, a codec (CODEC) 23 for encoding an image signal during recording and decoding during playback, and an encoded image signal (encoded image signal) A media drive 24 that records on the recording medium 25 and reads an encoded image signal from the recording medium 25, and an electric video display that displays a video for composition determination. Over finder (EVF) 21, a display 22 for displaying the image of the reproduced image signal and,, and a motion detector 26 for detecting the imaging apparatus 1 itself moves.

  The control unit 11 controls each unit of the imaging device 1 connected via the bus 13 by executing a control program recorded in the memory 12. For example, control information for controlling the driving of the zoom lens is notified to the pre-driver 15 corresponding to the operation information about zoom notified from the operation input unit 14, or based on the evaluation value supplied from the AF unit 20. Control information for controlling the drive of the focus lens to the pre-driver 15 is notified. Note that functional blocks related to autofocus control by the control unit 11 will be described later with reference to FIG.

  In the memory 12, in addition to the control program described above, the relationship between the zoom lens and the focus lens included in the lens group 17, more specifically, the focus lens in a state of being focused on a specific distance is stored in the zoom lens. A zoom tracking curve indicating a trajectory when driving in accordance with the change in magnification is held.

  The operation input unit 14 includes a user interface including a switch, a button, a ring, and the like for performing an auto focus function valid / invalid switching operation, a zoom lens telephoto / wide angle adjustment operation, a manual focus operation, and the like. Operation information corresponding to the operation is notified to the control unit 11 via the bus 13.

  The pre-driver 15 controls the operation of the lens driving unit 16 in accordance with control related to focus and zoom from the control unit 11. The lens driving unit 16 drives a focus lens, a zoom lens, and an aperture included in the lens group 17 in accordance with control from the pre-driver 15. Then, the control unit 11 is notified of the position of the focus lens, the position of the zoom lens, and the aperture value via the pre-driver 15 and the bus 13. This notification is used for calculating the depth of field.

  The image sensor 18 photoelectrically converts the optical image of the subject focused by the lens group 17 and outputs an image signal, which is an electrical signal obtained as a result, to the image signal processing unit 19.

  The image signal processing unit 19 performs predetermined image processing on the image signal input from the image sensor 18 or the image signal read from the recording medium 25 and outputs it to the subsequent stage.

  The AF unit 20 generates a luminance component (Y signal) based on the image signal input from the image sensor 18 in the previous stage, extracts a high-frequency component of the generated Y signal, and calculates the maximum value for each column of the absolute value. A detection value is generated by detecting and integrating. This detection value is supplied to the control unit 11 at the subsequent stage as an evaluation value indicating the degree of focusing.

  The motion detection unit 26 includes, for example, an acceleration sensor or an angular velocity sensor, and notifies the control unit 11 of motion information indicating the detection result via the bus 13.

  Next, FIG. 2 shows functional blocks for controlling the focus lens during autofocus, which is realized by the control unit 11 executing a control program.

  The motion determination unit 41 determines whether the panning operation or the tilting operation is being performed by the user based on the motion information notified from the motion detection unit 26. Further, the operation determination unit 41 determines whether or not a zooming operation (zoom lens telephoto / wide-angle adjustment) is being performed based on operation information notified from the operation input unit 14. The determination result is notified to the evaluation value acquisition unit 42.

  That is, when any of the panning operation, the tilting operation, or the zooming operation is being performed by the user, the captured image has a motion, so that the deterioration of the image quality due to wobbling does not cause a problem. Therefore, the normal wobbling width is applied without suppressing the wobbling width. The user does not perform any panning operation, tilting operation, or zooming operation, and the wobbling width is suppressed under a predetermined condition.

  The evaluation value acquisition unit 42 removes noise of the evaluation value indicating the degree of focusing supplied from the AF unit 20 by a built-in low-pass filter or the like, accumulates it for a predetermined period, and performs perspective evaluation based on the accumulated evaluation value A value change amount and a near-far evaluation value change amount (described later) are calculated. Further, the evaluation value acquisition unit 42 focuses on the AF control unit 45 that controls the movement of the focus lens in order to obtain an evaluation value for calculating a near-far evaluation value change amount and a near-far evaluation value change amount (described later). Request a small movement of the lens from far to near or from near to far.

  The depth-of-field calculating unit 43 is based on the aperture value of the lens group 17, the position of the focus lens, the position of the zoom lens, and the number of pixels of the image sensor 18 notified from the lens driving unit 16. The depth is calculated and notified to the wobbling width determination unit 44.

  The wobbling width determination unit 44 determines whether or not to suppress the wobbling width based on the perspective evaluation value change amount calculated by the evaluation value acquisition unit 42 and the near-field evaluation value change amount. If not suppressed, the wobbling width is determined to be a width corresponding to about ½ of the calculated depth of field. In the case of suppression, the wobbling width is determined to be a width corresponding to about ¼ of the calculated depth of field. However, when the width corresponding to about 1/4 of the calculated depth of field is narrower than the minimum wobbling width of the focus lens (depending on the performance of the motor built in the lens driving unit 16), the wobbling width Is the minimum wobbling width. The determined wobbling width is notified to the AF control unit 45.

  The AF control unit 45 generates a control signal for moving the focus lens from far to near or from near to far with a width corresponding to about ½ of the depth of field in accordance with a request from the evaluation value acquiring unit. And output to the pre-driver 15 via the bus 13. The AF control unit 45 generates a control signal for controlling the movement of the focus lens based on the evaluation value indicating the degree of focusing supplied from the AF unit 20, and the pre-driver 15 via the bus 13. Output to. Further, the AF control unit 45 generates a control signal for wobbling the focus lens based on the wobbling width determined by the wobbling width determination unit 44 and outputs the control signal to the pre-driver 15 via the bus 13.

  Next, the process of determining the wobbling width when the wobbling mode is set during autofocus will be described with reference to the flowchart of FIG.

  In step S <b> 1, the motion determination unit 41 performs any of panning operation, tilting operation, or zooming operation by the user based on the motion information notified from the motion detection unit 26 or the operation information notified from the operation input unit 14. It is determined whether or not the process is being performed. When it is determined that none of the panning operation, tilting operation, and zooming operation is performed by the user, the determination result is notified to the evaluation value acquisition unit 42, and the process proceeds to step S2 in order to suppress the wobbling width. It is advanced.

  In step S <b> 2, the depth-of-field calculating unit 43 is based on the aperture value of the lens group 17, the position of the focus lens, the position of the zoom lens, and the number of pixels of the image sensor 18 notified from the lens driving unit 16. The depth of field is calculated and notified to the wobbling width determination unit 44.

  In step S3, the evaluation value acquisition unit 42 obtains an evaluation value for calculating the near-far evaluation value change amount and the near-far evaluation value change amount with respect to the AF control unit 45 that controls the movement of the focus lens. Request a small movement from far to near or from near to far. In response to this request, the AF control unit 45 slightly moves the focus lens from far to near or from near to far with a width corresponding to about ½ of the depth of field. Specifically, as shown in FIG. 4, before and after the exposure period of the image sensor 18, the focus lens is slightly moved alternately from far to near or from near to far.

  Then, the evaluation value acquisition unit 42 calculates the difference between the evaluation values acquired when the focus lens is slightly moved from far to near as the distance evaluation value change amount, or the focus lens as the distance evaluation value change amount. The difference between the evaluation values acquired when is moved slightly from near to far is calculated. The calculated perspective evaluation value change amount or perspective evaluation value change amount is notified to the wobbling width determination unit 44.

  In step S4, the wobbling width determination unit 44 inputs the perspective evaluation value change amount (or perspective evaluation value change amount) input this time and the near-point evaluation value change amount (or near-field evaluation value change amount) input last time. Calculate the difference. In step S5, the wobbling width determination unit 44 calculates the near-evaluation value change amount input this time (or the near-evaluation value change amount) calculated in step S4 and the near-evaluation value change amount input last time (or near-distance). It is determined whether or not the difference from the (evaluation value change amount) is larger than a preset threshold value. When it is determined that the difference is larger than the threshold value, it is sufficiently effective even when the wobbling width of the focus lens is a width corresponding to about ½ of the depth of field, and even if the wobbling width is narrowed. Since it can be determined that there is no hindrance, the process proceeds to step S6 in order to suppress the wobbling width.

  In step S6, the wobbling width determination unit 44 determines whether or not the width corresponding to about 1/4 of the depth of field is wider than the minimum wobbling width of the focus lens. If it is determined that the width corresponding to about 1/4 of the depth of field is wider than the minimum wobbling width of the focus lens, the process proceeds to step S7, where the wobbling width corresponds to about 1/4 of the depth of field. To the AF control unit 45.

  Conversely, in step S6, the width corresponding to about 1/4 of the depth of field is not wider than the minimum wobbling width of the focus lens, that is, the width corresponding to about 1/4 of the depth of field is If it is determined that it is equal to or smaller than the minimum wobbling width of the focus lens, the process proceeds to step S8, where the wobbling width is determined as the minimum wobbling width of the focus lens, and is notified to the AF control unit 45. In response to this notification, as shown in FIG. 4, the AF control unit 45 reduces the depth of field to about ¼ until the next perspective evaluation value change amount (or perspective evaluation value change amount) acquisition timing. The autofocus control is performed in the wobbling mode that adopts the corresponding width or the minimum wobbling width.

  If it is determined in step S1 that at least one of the panning operation, the tilting operation, and the zooming operation is performed by the user, there is a meaning of suppressing the wobbling width due to the movement of the captured image. There is no suppression of the wobbling width. In order to obtain a normal wobbling width, the process proceeds to step S9.

  In step S9, the depth of field is calculated and notified to the wobbling width determination unit 44, as in the process of step S2.

  In step S <b> 10, the wobbling width determination unit 44 determines the wobbling width as a width corresponding to about ½ of the depth of field, and notifies the AF control unit 45. In response to this notification, as shown in FIG. 4, the AF control unit 45 reduces the depth of field to about ½ until the next perspective evaluation value change amount (or perspective evaluation value change amount) acquisition timing. The autofocus control is performed by the wobbling mode adopting the corresponding width.

  In step S5, the distance evaluation value change amount input this time (or distance evaluation value change amount) calculated in step S4 and the distance evaluation value change amount input last time (or distance evaluation value change amount). ) Is not larger than a preset threshold value, the effect of wobbling is lost if the wobbling width is further narrowed, so that the process proceeds to step S10 in order not to suppress the wobbling width. .

  This is the end of the description of the wobbling width control process. According to the wobbling width control process described above, when the panning operation, tilting operation, and zooming operation are not performed by the user, there is no depth of field corresponding to the normal wobbling width. When the evaluation value when the focus lens is moved with a minute width corresponding to about ½ changes sufficiently effectively, the wobbling width is suppressed to a width corresponding to about ¼, thereby wobbling. It is possible to suppress the deterioration of image quality that the image is visually recognized.

  Incidentally, in addition to the wobbling width control process described above, the wobbling width may be controlled using the following three examples.

  For example, when a first high-frequency component for determining sharpness and a second high-frequency component having a frequency lower than the first high-frequency component are detected and the second frequency component is larger than the first high-frequency component, a low-contrast object is detected. In this case, the wobbling amplitude may be maximized in order to improve the direction determination capability, and in other cases, the wobbling amplitude may be suppressed (decreased).

  Further, for example, the depth of field is deep on the wide angle side, and the focus lens has a sufficient control margin. Therefore, on the wide angle side, the wobbling width may be reduced to about 1/4 of the depth of field.

  Further, for example, as shown in FIG. 5, when a high-luminance subject exists in both the perspective (in the case of perspective conflict), when only a low-contrast subject exists as shown in FIG. In each of the cases where only a high-contrast object exists as shown in FIG. 6B, the wobbling width may be controlled to be narrow in the region indicated by x, and the wobbling width may be increased in the region indicated by ○.

To determine the area indicated by ×, use the ratio of the near-field evaluation value change amount and the near-field evaluation value change amount of the high-frequency detection value to determine the vicinity of the inflection point of the evaluation value ratio curve indicated by ×. can do.
More specifically,
| Perspective Evaluation Value Change -Near Evaluation Value Change | / | Perspective Evaluation Value Change + Near Evaluation Value Change |
When the differential amount (a suitable example is a difference between the evaluation value 1V before and the evaluation value) is larger than a fixed amount threshold value determined for each detection, the wobbling amplitude is controlled to be narrow. As a result, the wobbling amplitude is suppressed in the vicinity of the focal point and in the vicinity of the near and far conflict point.

  In addition, for example, when there is a high-luminance subject that is determined using a counter whose threshold is controlled by subject luminance, and there are various perspective conflict determination conditions, such as when the detection frame is the largest among the detection frames that can be set. When the near / far conflict is determined, the wobbling width may be decreased.

  In addition, the wobbling width affects wobbling responsiveness, visibility, and stability, but the autofocusing speed itself can be controlled as an independent parameter. It does not mean lowering the speed.

  As described above, according to the imaging apparatus 1 to which the present invention is applied, an image caused by wobbling of the focus lens that may have been visually recognized during high-accuracy image capturing without sacrificing the focusing performance. Deterioration can be suppressed.

  In this specification, the steps executed based on the program are executed in parallel or individually even if they are not necessarily processed in time series, as well as processes executed in time series according to the described order. It also includes processing.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

It is a block diagram which shows the structural example of the imaging device to which this invention is applied. It is a figure which shows the functional block for controlling a focus lens at the time of autofocus implement | achieved by the control part. It is a flowchart explaining a wobbling width control process. It is a figure which shows the acquisition timing of a near-far evaluation value variation | change_quantity and a near-far evaluation value variation | change_quantity. It is a figure for demonstrating the example of wobbling width control. It is a figure for demonstrating the example of wobbling width control. It is a figure for demonstrating the example of wobbling width control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Imaging device, 11 Control part, 12 Memory, 14 Operation input part, 17 Lens group, 18 Image sensor, 19 Image signal processing part, 20 AF part, 26 Motion detection part, 41 Motion determination part, 42 Evaluation value acquisition part, 43 Depth of Field Calculation Unit, 44 Wobbling Width Determination Unit, 45 AF Control Unit

Claims (5)

In an imaging device with an autofocus function that captures an image signal of a subject,
Calculation means for calculating an evaluation value indicating the degree of focusing based on the imaged image signal;
A focus control means for causing the focus lens to focus on the subject by wobbling a focus lens with a predetermined wobbling width based on the evaluation value;
An imaging apparatus including: a wobbling width determining unit that limits the wobbling width from the initial value based on a history of a change amount of the evaluation value obtained when the focus lens is moved at an initial value of the wobbling width. . The wobbling width determining means determines the wobbling width to be ½ of the depth of field based on the history of the change amount of the evaluation value obtained when the focus lens is moved with the initial value of the wobbling width. The imaging apparatus according to claim 1, wherein the width corresponding to about ¼ is limited to the width corresponding to about ¼ of the depth of field from the initial value of the width corresponding to the degree. A detecting unit for detecting at least one of a zooming operation, a panning operation, and a tilting operation by a user;
The wobbling width determining means stops the restriction of the wobbling width and determines the wobbling width when at least one of the zooming operation, the panning operation, or the tilting operation is detected by the detecting means. The imaging device according to claim 1, wherein the imaging device is determined as an initial value. In an imaging method of an imaging device having an autofocus function for imaging an image signal of a subject,
A calculation step of calculating an evaluation value indicating a degree of focusing based on the imaged image signal;
A focus control step for causing the focus lens to focus on the subject by wobbling a focus lens with a predetermined wobbling width based on the evaluation value;
The wobbling width determination step of limiting the wobbling width from the initial value based on the history of the change amount of the evaluation value obtained when the focus lens is moved at the initial value of the wobbling width. . A program for controlling an imaging device having an autofocus function for capturing an image signal of a subject,
A calculation step of calculating an evaluation value indicating a degree of focusing based on the imaged image signal;
A focus control step for causing the focus lens to focus on the subject by wobbling a focus lens with a predetermined wobbling width based on the evaluation value;
A wobbling width determination step for limiting the wobbling width from the initial value based on a history of changes in the evaluation value obtained when the focus lens is moved at the initial value of the wobbling width. A program to be executed by a computer of an imaging apparatus.

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