JP2003121721A - Imaging device and its focusing control method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging device and its focusing control method, and program which improve the durability of a focusing motor driving a focusing lens. SOLUTION: A monitor camera as the imaging device is equipped with the focusing lens and a microcomputer 9 which perform fine driving in a focusing direction when re-focusing operation is performed. The microcomputer 9 sets a threshold for deciding whether or not the re-focusing operation is carried out and varies the width of the fine driving of the focusing lens 4 when the re-focusing operation is carried out according to the set threshold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic focus adjustment (autofocus: AF) for automatically focusing a subject image.
The present invention relates to an image pickup apparatus including the apparatus, a focusing control method thereof, and a program.

[0002]

2. Description of the Related Art In recent years, the development of image pickup devices has been remarkable, and in particular, in order to improve the function and operability thereof, automatic focus adjustment devices and the like have come to be standardly equipped.

Such an automatic focus adjusting device detects a sharpness of a screen from a video signal obtained by photoelectrically converting a subject image by an image pickup device or the like, and a focus lens (focus adjustment) is made to maximize it. Position) to control the focus.

As the evaluation of the sharpness, generally, the intensity of the high frequency component of the video signal extracted by a band pass filter (BPF) or the blur width of the video signal extracted by a differentiating circuit (the edge portion of the subject image Width) strength is used.

For example, in the method of adjusting the focus by evaluating the sharpness based on the detection strength of the blur width, when a normal subject image is taken, the high-frequency component level is small and the blur width is large in the defocused state. By using the fact that the high-frequency component level increases and the blur width decreases as the focus becomes closer, the position where the high-frequency component level is maximum and the blur width is minimum reached the in-focus point completely. This is performed by controlling the position of the focus lens, which is regarded as the state.

Therefore, when the sharpness is low, the focus lens is driven as fast as possible in a direction in which the sharpness becomes high, and the focus lens is decelerated as the sharpness becomes higher so that the focus lens is accurately stopped at the peak of the sharpness. Controlled by. Such a method is generally referred to as a hill-climbing auto focus (hill-climbing AF) method.

Further, even after the focus lens is stopped at the peak of the sharpness by the autofocus function, the sharpness signal is continuously extracted from the video signal, and the focus adjustment is performed again when the subject changes. As a result, it is controlled so that it always stops at the peak of sharpness.

By adopting such an automatic focus adjusting device, conventionally, particularly in an image pickup device for picking up a moving image,
The operability has improved dramatically, and the autofocus function has become an essential function in recent years.

[0009]

However, in the above-described autofocus function, when the subject changes, the threshold value for whether focus adjustment is performed again is constant, so the subject changes significantly. Under the shooting conditions, the focus lens constantly moves, and the operation of searching for the peak of the sharpness is repeated. As a result, the motor that drives the focus lens is kept in a continuous rotation state, and durability is significantly reduced.

On the other hand, a method is known in which the autofocus function is switched to the manual focus mode and the focus motor for driving the focus lens is stopped to prevent the focus motor from continuously rotating. , It is possible to prevent deterioration of the durability of the focus motor that drives the focus lens. The burden on the side increases.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image pickup apparatus and a focusing control thereof for improving the durability of a focus motor for driving a focus lens. To provide a method and a program.

[0012]

In order to achieve the above object, an image pickup device according to claim 1 is an image pickup lens which focuses light from a subject on a focus, a focus adjusting lens which adjusts the focus, and Detecting means for periodically detecting a predetermined value according to the adjusted focus degree of focus, and focusing means for causing the focus adjustment lens to perform the focus operation according to the detected predetermined value. Calculating means for calculating a change amount between the predetermined value detected after the focusing operation of the focus and the predetermined value detected one cycle later, and the calculated change amount relates to the predetermined value. A discriminating means for discriminating whether or not it is larger than a threshold value, and a refocusing for refocusing by slightly driving the focus adjusting lens in the focusing direction when the calculated change amount is larger than the threshold value. In an imaging device including a focusing means, And setting means for setting the serial threshold,
And a changing unit for changing the width of the minute drive according to the set threshold value.

According to a second aspect of the present invention, there is provided the image pickup device according to the first aspect, wherein the predetermined value is a sharpness of a sharpness signal.

According to a third aspect of the present invention, in the image pickup apparatus according to the first aspect, the predetermined value is photometric data.

An image pickup apparatus according to a fourth aspect is the image pickup apparatus according to any one of the first to third aspects, wherein the setting means comprises an input means for a user to input the threshold value. And

According to a fifth aspect of the present invention, in the image pickup apparatus according to any one of the first to third aspects, the setting means sets the threshold value according to time. .

According to a sixth aspect of the present invention, in the image pickup apparatus according to the fifth aspect, the setting means further comprises input means for inputting the threshold value set by a user according to time. And

In order to achieve the above object, a focusing control method according to a seventh aspect of the present invention is a combination of an image pickup apparatus including an image pickup lens that focuses light from a subject on a focus and a focus adjustment lens that adjusts the focus. A focus control method, comprising: a detecting step of periodically detecting a predetermined value corresponding to the adjusted focus degree of the focus; and a focus adjustment of the focus adjustment lens according to the detected predetermined value. A focusing step for performing a focusing operation; a calculation step for calculating a change amount between the predetermined value detected after the focus operation for the focus and the predetermined value detected one cycle later; A determination step of determining whether the amount of change is greater than a threshold value for the predetermined value, and when the calculated amount of change is greater than the threshold value, the focus adjustment lens is slightly driven in the focusing direction. Let refocus That re-focus and a step, a setting step of setting the threshold value, characterized in that it comprises a changing means for changing the width of the finely driven in accordance with the set threshold value.

The focusing control method according to claim 8 is the method according to claim 7.
In the focusing control method described above, the predetermined value is a sharpness of a sharpness signal.

A focusing control method according to a ninth aspect is the seventh aspect.
In the focusing control method described above, the predetermined value is photometric data.

A focusing control method according to a tenth aspect is the focusing control method according to any one of the seventh to tenth aspects, wherein in the setting step, the threshold value is set by a user. Characterize.

The focus control method according to claim 11 is the focus control method according to any one of claims 7 to 10, wherein the setting step sets the threshold value according to time. Is characterized by.

A focusing control method according to a twelfth aspect is the focusing control method according to the eleventh aspect, wherein the setting step further comprises an input step of inputting the threshold value set by a user according to time. It is characterized by having.

In order to achieve the above object, a program according to a thirteenth aspect of the present invention provides a focus control method for an image pickup apparatus comprising an image pickup lens that focuses light from a subject on a focus and a focus adjustment lens that adjusts the focus. A program to be executed, which comprises a detecting step of detecting a predetermined value according to the adjusted focus degree of the adjusted focus, and an operation of focusing the focus on the focus adjustment lens according to the detected predetermined value. A focusing step to be performed, a calculation step of calculating a change amount between the predetermined value detected after the focus operation of the focus and the predetermined value detected one cycle later, and the calculated change amount Is greater than a threshold value related to the predetermined value, and when the calculated change amount is greater than the threshold value, the focus adjustment lens is slightly driven in the focusing direction. In a program for causing a computer to execute a refocusing step for refocusing, a setting step for setting the threshold value and a changing means for changing the width of the minute drive according to the set threshold value are provided. It is characterized by being provided.

[0025]

DETAILED DESCRIPTION OF THE INVENTION An image pickup apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of an image pickup apparatus according to the first embodiment of the present invention.

Referring to FIG. 1, a surveillance camera as an image pickup apparatus according to the first embodiment of the present invention includes a fixed lens 1,
The variable magnification lens 2, the second fixed lens 3, the focus adjustment and variable magnification lens 4 which is a focus lens (focus adjustment lens) for correcting the focal plane, and the imaging device 5 on which focused light forms an image.
Equipped with. Each of these lenses 1 to 4 is arranged in a line so as to focus the light from the subject on the imaging element 5.

The surveillance camera further includes a microcomputer (microcomputer) 9 for controlling the surveillance camera as a whole, an amplifier 6 for amplifying a signal detected by the image pickup device 5, and a camera process circuit 7 for separating a luminance signal from the amplified signal. , The microcomputer 9 uses a part of the separated luminance signal as a sharpness signal.
And a bandpass filter 8 for transmitting to.

The microcomputer 9 also uses the focus lens 4
The moving amount is detected by the encoder 12 and the amplified signal is acquired by the amplifier 6.

The variable-magnification lens 2 is driven by a variable-magnification motor 14 via a variable-magnification motor driver 13 according to a variable-magnification command from the microcomputer 9, while the focus lens 4 is driven by a focus adjustment command from the microcomputer 9. Focus motor 11 via focus motor driver 10
Driven by.

The microcomputer 9 is a so-called one-chip microcomputer and includes a CPU, RAM and ROM. The ROM stores a control program for controlling the focus motor driver 10 and the zoom motor driver 13, and adjustment data for the zoom lens 2 and the focus lens 5. A non-volatile RAM is used as the RAM, for example.

In the first embodiment, the light passing through each of the lenses 1 to 4 forms an image on the image pickup device 5 and is converted into an electric signal, and this signal is amplified by the amplifier 6. , To the camera process circuit 7. The luminance signal separated in the camera process circuit 7 becomes a sharpness signal by passing through the band pass filter 8. When the microcomputer 9 detects the sharpness signal, it issues a drive command to the focus motor driver 10 to output the focus motor 11
The focus lens 4 is driven by to adjust the focus. In the focus adjustment, when the sharpness of the sharpness signal is low, the focus lens 4 is driven as fast as possible in a direction in which the sharpness signal is high, and the focus is decelerated as the sharpness increases.
It is controlled by an autofocus process that stops at the top of a mountain with high precision.

This sharpness signal is periodically sent to the microcomputer 9 at a predetermined frame rate even after the focus is adjusted by the above-mentioned autofocus processing, and the microcomputer 9
When it is determined by the refocusing operation determination process of FIG. 2 described later that the refocusing operation is started (the amount of change in the sharpness of the sharpness signal sent periodically is determined from the threshold value stored in the RAM). (When it is larger), the refocusing operation of slightly driving the focus lens 4 in the focusing direction is performed after changing the width of the minute drive of the focus lens 4 according to the threshold value.

Specifically, the larger the threshold value is, the larger the width of the minute drive of the focus lens 4 during the refocusing operation is. On the contrary, the smaller the threshold value is, the more the refocusing operation is performed. The width of the minute drive of the focus lens 4 becomes small. During this refocusing operation, the focus lens 4 is precisely driven by being monitored by the encoder 12.

The predetermined frame rate is NTSC.
(National Television System Committee), but is not limited to this, and PAL (Phase A
lternation by Line) and SECAM (Sequential Cou
leus Avec Memoire).

FIG. 2 is a flow chart of the refocusing operation determination processing by the surveillance camera according to the first embodiment of the present invention.

This processing is for determining whether or not the focusing operation of the focus lens 4 is performed again after the focusing operation.
It is executed every time the sharpness signal is periodically transmitted to the microcomputer 9 at the NTSC frame rate.

In FIG. 2, first, a sharpness signal at the current position of the focus lens 4 is fetched (step S101), and the threshold value stored in advance in the RAM of the microcomputer 9 is input through an interface (not shown). The threshold value is reset by multiplying by the coefficient according to the user specified data (step S102).

In the following step S103, step S1
The amount of change between the sharpness of the current value of the sharpness signal captured in 01 and the sharpness of the previous value of the sharpness signal recorded in the RAM of the microcomputer 9 is calculated, and this amount of change is calculated in step S102. It is determined whether or not it is larger than the reset threshold value. As a result, it is possible to determine whether or not the subject image is in focus on the photographing element 5.

Specifically, when the amount of change in the sharpness of the captured sharpness signal is smaller than the threshold value stored in the RAM in the microcomputer 9, the subject image is focused on the photographing element 5. Consider it to be.

As a result of the determination in step S103, if the amount of change is larger than the threshold value (YES in step S103).
S), after changing the width of the minute drive of the focus lens 4, a refocusing operation of slightly driving the focus lens 4 in the focusing direction is executed (step S104), while the change amount is smaller than the threshold value. When (N in step S103
O), this processing is immediately terminated without executing the refocusing operation start processing.

According to the processing shown in FIG. 2, the microcomputer 9 calculates and resets the amount of change in the sharpness of the sharpness signal that is periodically fetched based on the user-specified data input through the interface (not shown). When it is larger than the threshold value (YES in step S103), after changing the width of the minute drive of the focus lens 4 according to the threshold value, the refocusing operation of slightly driving the focus lens 4 in the focusing direction is performed ( In step S104), the user can improve the durability of the focus motor 11 by preventing the focus lens 4 from continuing to move by changing the user setting data according to the shooting conditions such as the movement of the subject. Moreover, power saving can be achieved.

For example, when the subject is under photographing conditions that change frequently, the user setting data may be changed so that the threshold value is reset to a high value. In addition, when monitoring the situation during the day, under a shooting condition with a large depth of focus, that is, by increasing the threshold value and increasing the width of the minute drive of the focus lens 4 when performing the refocusing operation. It is also effective to change the user setting data so that the threshold value is reset to a high value when the shooting condition is such that the in-focus state can be maintained.

Next, the structure and operation of the image pickup apparatus according to the second embodiment of the present invention will be described.

The surveillance camera as the image pickup apparatus according to the present embodiment is basically the same as the surveillance camera of FIG. 1, and the same components as those of FIG. The description is omitted.

Further, in the present embodiment, the amplified signal amplified by the amplifier 6 is periodically sent to the microcomputer 9 as photometric data at the above frame rate without passing through the camera process circuit 7 and the bandpass filter 8. Sent.

FIG. 3 is a flowchart of the refocusing operation determination processing by the surveillance camera according to the second embodiment of the present invention.

Similar to the first embodiment, this process is a process for determining whether or not the focus lens 4 should be refocused after the focusing operation, and the photometric data is sent by the microcomputer at the frame rate of NTSC. 9 is executed every time it is transmitted to the server.

In FIG. 3, first, the photometric data at the current position of the focus lens 4 is fetched (step S201), and the threshold value stored in advance in the RAM of the microcomputer 9 is input through an interface (not shown). The threshold is reset by multiplying by a coefficient according to the user specified data.

In the following step S203, step S2
This time the photometric data captured in 01 and the microcomputer 9
The amount of change from the current value of the photometric data recorded in the internal RAM is calculated, and it is determined whether this amount of change is larger than the threshold value reset in step S202. As a result, it is possible to determine whether or not the subject image is in focus on the photographing element 5.

Specifically, when the amount of change in the captured photometric data is smaller than the threshold value stored in the RAM of the microcomputer 9, it is considered that the subject image is focused on the photographing element 5.

If the change amount is larger than the threshold value as a result of the determination in step S203 (YES in step S203).
S) After the fine driving width of the focus lens 4 is changed, a refocusing operation of slightly driving the focus lens 4 in the focusing direction is executed, and the focus lens 4 is determined by the reset threshold value. When the amount of change is smaller than the threshold value (NO in step S203), the process is ended without executing the refocusing operation.

According to the processing of FIG. 3, the change amount of the photometric data that is periodically taken in is determined by the microcomputer 9 based on the user-specified data input by the interface (not shown).
Is larger than the threshold value to be calculated / reset (YES in step S203), the refocusing operation for slightly driving the focus lens 4 in the focusing direction is performed after changing the width of the minute drive of the focus lens 4. Since (step S204), as in the case of the first embodiment, the user changes the user setting data in accordance with the shooting condition such as the change of the subject to prevent the focus lens 4 from continuously moving. Thus, the durability of the focus motor 11 can be improved, and further power saving can be achieved.

The structure and operation of the image pickup apparatus according to the third embodiment of the present invention will be described below.

The surveillance camera as the image pickup apparatus according to the present embodiment is basically the same as the surveillance camera of FIG. 1 except that it has a timer, and therefore, the same numbers are used for the same components. , Duplicate description is omitted.

FIG. 4 is a flowchart of the refocusing operation determination processing by the surveillance camera according to the third embodiment of the present invention.

In this process, in addition to the sharpness signal described above,
The data of the current time measured by the timer is periodically sent to the microcomputer 9 at the above frame rate.

In FIG. 4, first, the sharpness signal at the current position of the focus lens 4 is fetched (step S301), and the threshold value stored in advance in the RAM of the microcomputer 9 is input through an interface (not shown). The threshold value at the time of resetting is calculated by multiplying by the coefficient according to the user specified data (step S30).
2).

In the present embodiment, the user-specified data is input so that the threshold value for resetting calculated in step S302 becomes low. This is because the shooting environment is closed and there are many cases where there is little change in sharpness.
When the sharpness changes, it is determined that there is a high possibility of being an intruder such as a criminal. Therefore, the width of the minute drive of the focus lens 4 at the time of focus adjustment so that the in-focus state can be reliably maintained This is for narrowing.

However, for example, when the photographing environment is in a bright store where the store is open and the depth of focus is large, when the focus state can be maintained even if the width of the minute drive of the focus lens 4 at the time of focus adjustment is widened. The user-specified data having the higher threshold value for resetting calculated in step S302 may be input.

In the following step S303, the data of the current time measured by the timer is fetched, and then compared with the data of the opening time and the closing time stored in advance in the RAM of the microcomputer 9, thereby closing the store, namely, 19:
After 00, it is determined whether it is before 9:00 the next day (step S304).

As a result of the determination in step S304, when the store is not closed (NO in step S303), immediately when the store is closed (YES in step S303), the threshold value calculated in step S302 is set. After resetting to, proceed to step S305.

In step S305, step S301
The amount of change between the sharpness of the current value of the sharpness signal obtained in step S4 and the sharpness of the previous value of the sharpness signal recorded in the RAM of the microcomputer 9 is calculated, and this amount of change is calculated in step S30.
In step 4, it is determined whether or not the threshold value is larger than the reset threshold value.

As a result of the determination in step S305, if the change amount is larger than the threshold value (YES in step S305).
S), the refocusing operation start process is executed to drive the focus lens 4 with a minute driving width determined by a threshold value,
On the other hand, when the amount of change is smaller than the threshold value (NO in step S305), this process ends without executing the refocusing operation start process.

According to the processing of FIG. 4, when the current time is closed (YES in step S303), the threshold value calculated by the microcomputer 9 is reset to the threshold value calculated by the user specified data input through the interface (not shown). When the sharpness change amount of the sharpness signal periodically set is larger than the reset threshold value (YES in step S305), the focus lens 4 is set according to the threshold value. After changing the width of the minute drive, the refocusing operation of slightly driving the focus lens 4 in the focusing direction is performed (step S306), so that the sharpness change may be small in a store closed with a surveillance camera. The user changes the user setting data when it is determined that the number is high, and when it is determined that there is a high possibility that the person is an intruder such as a criminal when the sharpness changes. As a result it is possible to re-set the threshold to a low value, it is also possible shooting condition is changed to maintain the focus state reliably.

The refocusing operation determination process according to the third embodiment is not performed by the change amount of the sharpness of the sharpness signal and its threshold value, but by the change amount of the photometric data and its threshold value. You may go about.

Further, although the image pickup apparatus in the above-mentioned embodiment is a surveillance camera, it is not limited to this, and if it is a digital camera or other image pickup apparatus which electronically picks up an image, the refocusing operation is performed. Discrimination processing can be applied.

The object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer of the system or apparatus ( Alternatively, it is needless to say that it can be achieved by reading and executing the program code stored in the storage medium by the CPU or MPU).

In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. Moreover, not only the functions of the above-described embodiments are realized by executing the program code read by the computer, but also the OS or the like running on the computer executes actual processing based on the instructions of the program code. It goes without saying that a case where some or all is performed and the functions of the above-described embodiments are realized by the processing is also included.

Further, after the program code read from the storage medium is written in the storage medium provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, the program code is instructed. It goes without saying that a case where the CPU provided in the function expansion card or the function expansion unit performs a part or all of the actual processing based on this and the processing realizes the functions of the above-described embodiments is also included.

Another object of the present invention is to distribute the program code of the software that realizes the functions of the above-described embodiment via a network, thereby storing the storage means such as a hard disk or a memory of the system or apparatus, or C.
It is stored in a storage medium such as D-RW or CD-R, and the computer (or CPU or MP) of the system or device.
It is needless to say that U) is achieved by reading and executing the program code stored in the storage means or the storage medium.

[0072]

As described in detail above, according to the image pickup apparatus, the focusing control method and the program thereof of the present invention, the threshold value for determining whether or not the refocusing operation is executed is set, Since the width of the minute drive of the focus lens when the refocusing operation is executed is changed according to the set threshold value, the threshold value can be reset according to the shooting condition. It is possible to prevent the focus motor 11 from continuing to move, improve the durability of the focus motor 11, and save power.

Further, as a result of the improved durability, the image pickup apparatus according to the present invention has a long product life and can be used as a surveillance camera for long-time photographing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image pickup apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a refocusing operation determination process by the surveillance camera according to the first embodiment of the present invention.

FIG. 3 is a flowchart of refocusing operation determination processing by the surveillance camera according to the second embodiment of the present invention.

FIG. 4 is a flowchart of a refocusing operation determination process by the surveillance camera according to the third embodiment of the present invention.

[Explanation of symbols]

1 First fixed lens 2 zoom lens 3 Second fixed lens 4 focus lens 5 Image sensor 6 amplifier 7 Camera process circuit 8 bandpass filter 9 Microcomputer 10 Focus motor driver 11 Focus motor 12 encoder 13 Magnifying motor driver 14 Magnifying motor

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03B 13/36 G02B 7/11 NH 04N 5/232 G03B 3/00 AF term (reference) 2H002 GA54 2H011 AA01 BA31 BB04 2H044 DA01 2H051 AA01 BA45 BA47 DA15 DB01 5C022 AA01 AB29 AC69

Claims (13)

[Claims] 1. An imaging lens that focuses light from a subject on a focus, a focus adjustment lens that adjusts the focus, and a detection unit that periodically detects a predetermined value according to the degree of focus of the adjusted focus. A focusing means for causing the focus adjustment lens to perform the focus focusing operation according to the detected predetermined value; the predetermined value detected after the focus focusing operation; and one cycle thereof. A calculating unit that calculates the amount of change from the predetermined value detected later, a determining unit that determines whether the calculated amount of change is greater than a threshold value related to the predetermined value, and the calculated amount of change Is slightly larger than the threshold value, the focus adjustment lens is slightly driven in the focusing direction, and an image pickup apparatus comprising refocusing means for refocusing, setting means for setting the threshold value, and According to the set threshold Imaging apparatus characterized by comprising a changing means for changing the width of the micro drive. 2. The image pickup apparatus according to claim 1, wherein the predetermined value is a sharpness of a sharpness signal. 3. The image pickup apparatus according to claim 1, wherein the predetermined value is photometric data. 4. The setting means comprises an input means for a user to input the threshold value.
The image pickup apparatus according to any one of items 1 to 3. 5. The image pickup apparatus according to claim 1, wherein the setting unit sets the threshold according to time. 6. The image pickup apparatus according to claim 5, wherein the setting unit further includes an input unit for a user to input the threshold value set according to time. 7. A focus control method for an image pickup apparatus, comprising: an imaging lens that focuses light from a subject on a focus; and a focus adjustment lens that adjusts the focus, wherein a focus degree of the adjusted focus is adjusted. A detecting step of periodically detecting a predetermined value according to the detected value; a focusing step of causing the focus adjusting lens to perform the focusing operation of the focus according to the detected predetermined value; A calculation step of calculating a change amount between the predetermined value detected in step S1 and the predetermined value detected after one cycle, and whether or not the calculated change amount is larger than a threshold value related to the predetermined value. And a refocusing step of refocusing by slightly driving the focus adjustment lens in the focusing direction when the calculated change amount is larger than the threshold value. Set the value Focusing control method for an imaging apparatus characterized by comprising: a constant step, and changing means for changing the width of the finely driven in accordance with the set threshold value. 8. The focus control method according to claim 7, wherein the predetermined value is a sharpness of a sharpness signal. 9. The focusing control method according to claim 7, wherein the predetermined value is photometric data. 10. The focusing control method according to claim 7, wherein the threshold value is set by a user in the setting step. 11. The method according to claim 7, wherein the setting step sets the threshold value according to time.
The focus control method according to any one of 0. 12. The focus control method according to claim 11, wherein the setting step further comprises an input step of inputting the threshold value set by a user according to time. 13. A program for executing a focus control method of an image pickup apparatus, comprising: an image pickup lens that focuses light from a subject on a focus; and a focus adjustment lens that adjusts the focus. A detection step of detecting a predetermined value according to the focus degree, a focusing step of causing the focus adjustment lens to perform the focusing operation of the focus adjustment lens according to the detected predetermined value, and the focus focusing operation and thereafter. A calculation step of calculating a change amount between the predetermined value detected in step S1 and the predetermined value detected after one cycle, and whether or not the calculated change amount is larger than a threshold value related to the predetermined value. The computer performs a determination step of determining and a refocusing step of refocusing by slightly driving the focus adjustment lens in the focusing direction when the calculated change amount is larger than the threshold value. In the program, a setting step for setting the threshold value, and a changing means for changing the width of the minute drive according to the set threshold value are provided.