JP7481972B2 - Focus control device and program thereof, and imaging device - Google Patents

Description

The present invention relates to a focus control device that controls focus switching, a program for the same, and an imaging device.

Conventionally, when a television camera (imaging device) is used while mounted on a tripod or the like, the cameraman manually rotates a control knob on a focus adjustment remote control called a focus demand to focus the imaging lens (manual focus (MF)). In a typical focus demand, the rotation position of the control knob corresponds one-to-one to the focus position of the imaging lens. In addition, a typical focus demand has end points in the forward and backward directions of rotation, with the forward and rear end points corresponding to the infinity side and the minimum object distance (MOD) side, respectively. This allows the cameraman to estimate the focus position based on the rotation position of the control knob.

On the other hand, in an imaging device having an autofocus (AF) function, the cameraman may switch between AF and MF at his/her discretion. In this case, when switching from AF to MF, the focus ring of the imaging lens rotates with reference to the absolute position of the operation knob, which may cause an unintended change in focus.
To solve this problem, a focus demand that does not have an end point in the rotation direction of the operation knob is used. With this type of focus demand, the focus movement is always determined by the relative rotation angle from the current position of the operation knob, so that the focus position does not change when switching from AF to MF (see Patent Document 1).

JP 2020-20842 A

In the invention described in Patent Document 1, the movement of the focus is determined by the relative rotation angle of the operation knob, so the operation knob is designed so that it does not have end points.
However, if the operation knob does not have end points like this, it becomes difficult for the cameraman to grasp the focus position as the absolute position of the operation knob.
Therefore, an object of the present invention is to provide a focus control device and a program therefor, as well as an imaging device, that are capable of suppressing unintended focus movement by the photographer when switching from autofocus to manual focus, even when using a focus demand that has an end point in the rotation direction of the operating knob.

To solve the above problem, the focus control device according to the present invention is a focus control device that can switch between autofocus operation and manual focus operation that operates at a focus instruction position corresponding to the rotation position of an operation knob, controls the switching of focus operation for an imaging lens that outputs the current focus position and the focus instruction position, and is configured to include a difference calculation means, a focus operation selection means, and a focus operation switching means.

In such a configuration, the focus control device calculates the difference between the current focus position and the focus instruction position by the difference calculation means, whereby, when the imaging lens is performing an autofocus operation, it is possible to obtain the amount of change in the focus position when switching to a manual focus operation.
The focus control device also uses a focus operation selection means to select either autofocus or manual focus in response to an instruction from a cameraman who is an operator.

The focus control device then instructs the imaging lens to perform the focus operation selected by the focus operation selection means through the focus operation switching means, thereby switching to the focus operation desired by the operator.
Here, when the manual focus operation is selected by the focus operation selection means, the focus operation switching means instructs the imaging lens to perform the manual focus operation when the difference calculated by the difference calculation means becomes equal to or smaller than a preset threshold value.
This reduces fluctuations in focus position even when switching from autofocus to manual focus.

In order to solve the above problem, the focus control device according to the present invention is a focus control device that can switch between autofocus operation and manual focus operation that operates at a focus indication position corresponding to the rotation position of the operation knob, controls the switching of focus operation for an imaging lens that outputs the current focus position, and is configured to include a difference calculation means, a focus operation selection means, and a focus operation switching means.

In such a configuration, the focus control device calculates the difference between the current focus position of the imaging lens and the focus position one point before, which is a preset time interval, by a difference calculation means having a storage means for storing the focus position of the imaging lens at a preset time interval.
The focus control device uses a focus operation selection means to select either autofocus or manual focus in response to an instruction from a cameraman who is an operator.

The focus control device then instructs the imaging lens to perform the focus operation selected by the focus operation selection means through the focus operation switching means, thereby switching to the focus operation desired by the operator.
Here, when manual focus operation is selected by the focus operation selection means, the focus operation switching means instructs the imaging lens to alternate between manual focus operation and autofocus operation for a preset duration, and terminates the mutual switching between the focus operations when the difference during manual focus operation becomes equal to or less than a preset threshold value.
This allows the focus operation switching means to instantaneously acquire the focus position during manual focus operation during autofocus operation, and to transition to manual focus operation when the difference calculated by the difference calculation means becomes equal to or less than a preset threshold value.
The focus control device can be operated by a focus control program that causes a computer to function as each of the above-mentioned functional units.

In order to solve the above problem, the imaging device according to the present invention may be configured to include an autofocus operation unit that instructs the imaging lens to use a focus position determined by autofocus as an autofocus instruction position, a manual focus operation unit that instructs the imaging lens to use a focus position corresponding to the rotation position of an operation knob as a manual focus instruction position, the imaging lens that switches between autofocus operation and manual focus operation and moves the focus position to the autofocus instruction position or the manual focus instruction position, and a focus control device that inputs the current focus position and the manual focus instruction position of the imaging lens and controls the switching of the focus operation of the imaging lens.

To solve the above problem, the imaging device according to the present invention may be configured to include an autofocus operation unit that instructs the imaging lens to use a focus position determined by autofocus as an autofocus instruction position, a manual focus operation unit that instructs the imaging lens to use a focus position corresponding to the rotation position of an operation knob as a manual focus instruction position, the imaging lens that switches between autofocus operation and manual focus operation and moves the focus position to the autofocus instruction position or the manual focus instruction position, and a focus control device that inputs the current focus position of the imaging lens and controls the switching of the focus operation of the imaging lens.

The present invention provides the following excellent effects.
According to the present invention, even when a manual focus operation unit (focus demand) having a rotation end point on an operation knob is used, when switching from autofocus to manual focus, the switch occurs when the difference in focus position falls below a predetermined threshold value, thereby preventing unintended focus movement by the photographer.
As a result, the present invention can improve the operability of focus movement for the cameraman.

1 is a perspective view of an imaging device (television camera) equipped with a focus control device according to an embodiment of the present invention. FIG. 2 is a front view showing an example of an operation knob of a focus demand. 1 is a block diagram showing a configuration of a focus control device according to a first embodiment of the present invention; 5 is a flowchart showing an AF/MF switching operation of the focus control device according to the first embodiment of the present invention. 5A to 5D are explanatory diagrams for explaining the switching operation from AF to MF of the focus control device according to the first embodiment of the present invention in association with the operations of the operation knob of a focus demand. FIG. 11 is a block diagram showing the configuration of a focus control device according to a second embodiment of the present invention. 10 is a flowchart showing an AF/MF switching operation of a focus control device according to a second embodiment of the present invention. 13A to 13D are explanatory diagrams for explaining the switching operation from AF to MF of the focus control device according to the second embodiment of the present invention in association with the operations of the focus demand operation knob (a) to (d).

<<Full-pair configuration of imaging device>>
First, with reference to FIG. 1, the overall configuration of an image pickup apparatus equipped with a focus control device according to an embodiment of the present invention will be described.
The imaging device 100 is a camera that captures an image of a subject, and is a television camera used in a broadcasting station or the like.
Here, the imaging device 100 comprises an imaging lens 1 , a camera body 2 , an AF operation section 3 , an MF operation section 4 , a focus control device 5 , a viewfinder 6 , an operation arm 7 , and a camera platform 8 .

The imaging lens 1 is a typical camera lens including an optical system, a focus movement mechanism, etc. (not shown). Subject light incident on the imaging lens 1 is condensed according to the focus position and irradiated onto the camera body 2.
In response to an operational instruction from a focus control device 5, the imaging lens 1 moves the focus to either a focus position (AF instruction position) instructed by an AF operation unit 3 or a focus position (MF instruction position) instructed by an MF operation unit 4.

In addition, the imaging lens 1 is switchable between autofocus operation and manual focus operation that operates at a focus designation position corresponding to the rotational position of the operation knob, and has a function of outputting the current focus position and MF designation position.
The imaging lens 1B has the same functions as the imaging lens 1, but does not output the MF designated position and has the function of outputting only the current focus position to the focus control device 5B.

The camera body 2 converts subject light incident through the imaging lens 1 into a video signal. The camera body 2 is a general type, and therefore a detailed description thereof will be omitted.
The camera body 2 displays the captured image on a viewfinder 6, and outputs a video signal to the outside via a signal line (not shown).
In this embodiment, the camera body 2 includes an AF operation unit 3 therein.

The AF (autofocus) operation section 3 automatically adjusts the focus position of the imaging lens 1 to the in-focus position of the subject.
The AF operation unit 3 adjusts the focus position, for example, by an image plane phase difference method. The image plane phase difference method is a method for geometrically calculating the subject distance from the parallax between two-eye stereo images formed by a pixel pair for detecting the phase difference in one image sensor, and adjusting the focus position.
The AF operation unit 3 outputs a focus position (AF instruction position) to the imaging lens 1 .

The MF (manual focus) operation section 4 (focus demand) is used to manually move the focus position of the imaging lens 1 .
The MF operation unit 4 includes an operation knob 41 , and outputs a focus position corresponding to the rotation position of the operation knob 41 to the imaging lens 1 .
2, the operation knob 41 has a rotation mechanism (not shown) and its front and rear end points correspond to the infinity (INF) side and the closest distance (MOD) side, respectively. The rotation position of the operation knob 41 corresponds one-to-one to the focus position of the imaging lens 1.

The focus control device 5 controls switching of the focus operation of the imaging lens 1. The focus control device 5B corresponds to the imaging lens 1B that does not output an MF indication position, and controls switching of the focus operation of the imaging lens 1B.
The configuration and operation of the focus control devices 5 and 5B will be described later.

The viewfinder 6 displays the image captured through the imaging lens 1. This viewfinder 6 is used by the cameraman (operator) to check the image captured by moving the focus position of the imaging lens 1 by AF or MF.

The operating arm 7 is operated by a cameraman to move the orientation of the imaging lens 1 in a pan direction or a tilt direction.
The camera platform 8 is a platform on which the camera body 2 is mounted. The camera platform 8 is equipped with a pan mechanism and a tilt mechanism (not shown) that rotate in a pan direction and a tilt direction, and rotates in the pan direction or the tilt direction by the cameraman operating an operating arm 7 fixed to the camera platform 8.
The imaging device 100 configured in this manner is operated by the cameraman to switch between AF and MF to capture an image of a subject.

Configuration of Focus Control Device: First Embodiment
Next, the configuration of the focus control device 5 according to the first embodiment of the present invention will be described with reference to FIG.

The focus control device 5 controls the focus position of the imaging lens 1 so as to switch between AF control and MF control.
The focus control device 5 receives, from the imaging lens 1, the MF focus position (MF designated position) designated to the imaging lens 1 by the MF operation unit 4 and the current focus position.
Furthermore, when AF/MF switching is performed by the cameraman, the focus control device 5 outputs an instruction to switch the actual AF/MF operation (operation switching instruction) to the imaging lens 1 .
As shown in FIG. 3, the focus control device 5 includes a focus operation selection unit 50 , a threshold setting unit 51 , a difference calculation unit 52 , and a focus operation switching unit 53 .

The focus operation selection means 50 selects either the AF or MF focus operation in response to an instruction from a cameraman. The focus operation selection means 50 allows the cameraman to select the focus operation of the imaging lens 1 via a changeover switch or the like (not shown).
The focus operation selection means 50 outputs an instruction indicating the selected focus operation to the focus operation switching means 53 .

The threshold setting means 51 sets a threshold value that is the difference between the MF designated position and the current focus position and serves as a reference for switching from AF to MF. This threshold setting means 51 is set as a numerical value as the threshold value T by the photographer via an input means such as a numeric key (not shown). Note that if the threshold value T is a predetermined fixed value, it is not necessary to provide the threshold setting means 51, and it is sufficient that a fixed value is set in advance in the focus operation switching means 53.

The difference calculation means 52 calculates the difference between the current focus position and a focus instruction position corresponding to the rotation position of the operation knob. Here, the difference calculation means 52 calculates the difference between the current focus position output from the imaging lens 1 and the MF instruction position.
The difference calculation means 52 calculates the difference D as the absolute difference D=|F _P −F _M |, where F _M is the MF designated position and F _P is the current focus position.
The difference calculation means 52 outputs the calculated difference (absolute difference value) D to the focus operation switching means 53 .
It should be noted that the difference calculation means 52 does not need to constantly calculate the difference, and may perform the calculation in response to an instruction from the focus operation switching means 53 when the focus operation switching means 53 uses the difference.

The focus operation switching means 53 instructs the imaging lens 1 to perform the focus operation selected by the focus operation selection means 50 .
When the AF focus operation is selected while the imaging lens 1 is operating in MF, the focus operation switching means 53 outputs an operation switching instruction to switch from MF to AF to the imaging lens 1. As a result, the imaging lens 1 operates in AF.
The focus operation switching means 53 then stores in a memory (not shown) the state in which the current focus operation of the imaging lens 1 is AF.

On the other hand, when MF focus operation is selected while the imaging lens 1 is operating in AF, the focus operation switching means 53 performs the following control to transition the imaging lens 1 to a state in which it operates in MF.
First, when the MF focus operation is selected, the focus operation switching means 53 continues the AF operation and enters an operation switching standby state.
During the operation switching waiting state, the MF designated position output from the MF operation unit 4 is input to the focus control device 5 .
Then, in the operation switching waiting state, the focus operation switching means 53 compares the difference (absolute difference) D calculated by the difference calculation means 52 with the threshold value T set by the threshold setting means 51, and waits in the operation switching waiting state while the difference D is greater than the threshold value T. On the other hand, when the difference D becomes equal to or smaller than the threshold value T, the focus operation switching means 53 outputs an operation switching instruction to the imaging lens 1 to instruct switching from AF to MF. This causes the imaging lens 1 to enter a state in which it operates in MF.
The focus operation switching means 53 then stores in a memory (not shown) the state in which the current focus operation of the imaging lens 1 is MF.

By configuring as described above, when switching the focus operation from AF to MF, the focus control device 5 can switch the focus operation of the imaging lens 1 to MF when the difference between the focus position corresponding to the MF instruction position of the MF operation unit 4 and the current AF focus position becomes equal to or less than a predetermined threshold value.
This enables the focus control device 5 to suppress unintended focus movement when the focus operation is switched from AF to MF.
The focus control device 5 can be operated by a program (focus control program) for causing a computer (not shown) to function as each of the above-mentioned means.

<Operation of the Focus Control Device: First Embodiment>
Next, the operation (AF⇔MF switching operation) of the focus control device 5 according to the first embodiment of the present invention will be described with reference to Fig. 4 (for the configuration, refer to Fig. 3 as appropriate). Note that it is assumed here that the focus operation in the initial state of the imaging lens 1 is AF. It is also assumed that a threshold value T is set in advance by the threshold value setting means 51.

In step S1, the focus operation selection means 50 determines whether or not MF has been selected as the focus operation by a changeover switch or the like.
If MF is selected (Yes in step S1), the focus control device 5 advances the operation to step S2. On the other hand, if MF is not selected (No in step S1), the focus control device 5 maintains the state in which the imaging lens 1 is operating in AF.

In step S2, the difference calculation means 52 calculates a difference (absolute difference) D between the current focus position output from the imaging lens 1 and the MF designated position.
Here, the current focus position is the actual focus position at which the imaging lens 1 operates in AF, and the MF designated position is the focus position corresponding to the rotation position of the operation knob 41 of the MF operation unit 4.

In step S3, the focus operation switching means 53 determines whether the difference D calculated in step S2 is equal to or smaller than a preset threshold value T or not.
If the difference D is equal to or smaller than the threshold T (Yes in step S3), the focus control device 5 advances the operation to step S4. On the other hand, if the difference D is greater than the threshold T (No in step S3), the focus control device 5 returns the operation to step S2.
When the difference D is greater than the threshold value T, the cameraman rotates the operation knob 41 of the MF operation unit 4, thereby updating the MF designated position.

In step S4, the focus operation switching means 53 outputs an operation switching command to switch from AF to MF to the imaging lens 1. This causes the imaging lens 1 to enter a state in which it operates in MF.
In step S5, the focus operation selection means 50 determines whether or not AF has been selected as the focus operation by a changeover switch or the like.
If AF is selected (Yes in step S5), the focus control device 5 advances the operation to step S6. On the other hand, if AF is not selected (No in step S5), the focus control device 5 maintains the state in which the imaging lens 1 operates in MF.

In step S6, the focus operation switching means 53 outputs an operation switching command to switch from MF to AF to the imaging lens 1. This puts the imaging lens 1 into a state in which it operates in AF.
Then, the focus control device 5 returns to step S1 and repeats the operation.

By the above operation, the focus control device 5 can switch the focus operation of the imaging lens 1 between AF and MF. At this time, the focus control device 5 switches from AF to MF when the difference between the focus position corresponding to the MF instruction position and the current focus position becomes equal to or less than a predetermined threshold, thereby suppressing unintended focus movement.

<Operation knob movement>
With reference to FIG. 5, a schematic description will be given of the movement of the operation knob 41 of the MF operation unit 4 when switching from AF to MF in the case where the focus control device 5 is used.

Fig. 5(a) shows a state in which the imaging lens 1 is operating in AF. For example, even if a rotational position corresponding to the MF focus position F _M exists at an intermediate position between MOD and INF, that position does not change depending on the actual focus position F _P that changes due to AF. In Fig. 5, the rotational position corresponding to the MF focus position F _M is shown by a solid line on the operation knob 41, and the virtual rotational position corresponding to the AF focus position F _P is shown by a dashed line on the operation knob 41.

5B and 5C show a state in which MF has been selected as the focus operation.
5B, when MF is selected, the focus position F _M corresponding to the rotation position varies by rotating the operation knob 41. At this time, the imaging lens 1 does not move the focus position.

Then, as shown in FIG. 5C, when the difference D between the focus position F _{1 M} and the focus position F 1 _P becomes equal to or smaller than the threshold value T, the imaging lens 1 transitions to the MF focus operation.
At this stage, the focus position of the imaging lens 1 moves from the AF focus position F _{1 P} to the MF focus position F _{1 M} , but the amount of movement is equal to or less than the threshold value T.
As shown in FIG. 5D, the focus position F _M changes as the operation knob 41 is rotated.

<Configuration of Focus Control Device: Second Embodiment>
Next, the configuration of a focus control device 5B according to a second embodiment of the present invention will be described with reference to FIG.

The focus control device 5B switches between controlling the focus position of the imaging lens 1B by AF or MF.
The focus control device 5B receives the current focus position from the imaging lens 1B.
Furthermore, when AF/MF switching is performed by the cameraman, the focus control device 5B outputs an instruction to switch the actual AF/MF operation (operation switching instruction) to the imaging lens 1B.

As shown in FIG. 6, the focus control device 5B includes a focus operation selection unit 50, a threshold setting unit 51B, a difference calculation unit 52B, a focus operation switching unit 53B, and a time setting unit .
The focus operation selection means 50 has the same configuration as the focus control device 5 described with reference to FIG. 3, and therefore a description thereof will be omitted.

The threshold setting means 51B sets a threshold value that is a reference for switching from AF to MF, which is the difference between the current focus position and the focus position a predetermined time before (the immediately preceding focus position). In this threshold setting means 51B, a numerical value is set as the threshold value T by the cameraman via an input means such as numeric keys (not shown).
In addition, when the threshold value T is a predetermined fixed value, it is not necessary to provide the threshold value setting means 51B, and it is sufficient that the fixed value is set in advance in the focus operation switching means 53B.

The difference calculation means 52B calculates the difference between the current focus position of the imaging lens 1B and the focus position a preset time interval ago (the previous focus position) stored in the storage means M. The storage means M is a buffer that sequentially stores the focus position of the imaging lens 1B. The focus position stored in the storage means M that is a time t1 before the current time t is used as the previous focus position.
The difference calculation means 52B calculates the difference D from the absolute difference D=|F _P (t)-F _P (t-t1)|, where F _P (t) is the current focus position and F _P (t-t1) is the immediately previous focus position. Note that time t1 is the time set by the time setting means 54.
The difference calculation means 52B outputs the calculated difference (absolute difference value) D to the focus operation switching means 53B.
It should be noted that the difference calculation means 52B does not need to constantly calculate the difference, and may perform the calculation in response to an instruction from the focus operation switching means 53B when the focus operation switching means 53B uses the difference.

The focus operation switching means 53B instructs the image pickup lens 1B to perform the focus operation selected by the focus operation selection means 50.
When the AF focus operation is selected while the imaging lens 1B is operating in MF, the focus operation switching means 53B outputs an operation switching instruction to switch from MF to AF to the imaging lens 1B, so that the imaging lens 1B operates in AF.
The focus operation switching means 53B then stores in a memory (not shown) the state in which the current focus operation of the imaging lens 1B is AF.

On the other hand, when MF focus operation is selected while the imaging lens 1B is operating in AF, the focus operation switching means 53B performs the following control to transition the imaging lens 1B to a state in which it operates in MF.
First, the focus operation switching means 53B enters an operation switching standby state when the MF focus operation is selected.
During the operation switching waiting state, the focus operation switching means 53B periodically switches between the MF focus operation and the AF focus operation.
The focus operation switching means 53B transitions from the operation switching waiting state to a complete MF focus operation state when the difference D between the current focus position F _P (t) due to temporary switching from AF to MF and the immediately previous focus position F _P (t-1) becomes equal to or less than a threshold value T.

On the other hand, when a difference D between the current focus position F _P (t) due to temporary switching from AF to MF and the immediately previous focus position F _P (t-1) is greater than a threshold value T, the focus operation switching means 53B outputs an operation switching instruction to switch from MF to AF to the imaging lens 1B. Then, after a time t2 set by the time setting means 54 has elapsed, the focus operation switching means 53B outputs an operation switching instruction to switch from AF to MF to the imaging lens 1B.
In this way, when the focus operation switching means 53B is in a state waiting for switching of the operation, if there is a large difference between the focus position in MF and the focus position in the immediately preceding AF, it returns the operation to AF, and when the difference becomes small, it transitions to a complete MF focus operation state.

The time setting means 54 sets various times that regulate the operations within the focus control device 5B.
Here, the time setting means 54 sets a time t1 which is the time interval between focus positions used by the difference calculation means 52B, and a time t2 which is the AF operation time in the operation switching waiting state by the focus operation switching means 53B.
In this time setting means 54, numerical values are set as times t1 and t2 by the cameraman via input means such as numeric keys (not shown).
When the times t1 and t2 are set to predetermined fixed values, it is not necessary to provide the time setting means 54, and it is sufficient that the fixed values are set in advance in the difference calculation means 52B and the focus operation switching means 53B.

By configuring as described above, the focus control device 5B can switch the focus operation of the imaging lens 1 to MF when the difference between the focus position corresponding to the MF instruction position of the MF operation unit 4 and the AF focus position becomes small when switching the focus operation from AF to MF.
This allows the focus control device 5B to suppress unintended focus movement when the focus operation is switched from AF to MF.
The focus control device 5B can be operated by a program (focus control program) for causing a computer (not shown) to function as each of the above-mentioned means.

<Operation of the Focus Control Device: Second Embodiment>
Next, the operation (AF⇔MF switching operation) of the focus control device 5B according to the second embodiment of the present invention will be described with reference to Fig. 7 (for the configuration, refer to Fig. 6 as appropriate). It is assumed here that the focus operation in the initial state of the imaging lens 1B is AF. It is also assumed that a threshold value T is set in advance by the threshold value setting means 51B, and times t1 and t2 are set in advance by the time setting means 54.
The operations in steps S1, S5 to S6 are the same as those of the focus control device 5 described with reference to FIG. 4, and therefore will not be described here.

After MF is selected in step S1, in step S10, the focus operation switching means 53B outputs an operation switching instruction to switch from AF to MF to the imaging lens 1B, whereby the imaging lens 1B enters a state of operating in MF.
In step S11, the difference calculation means 52B calculates the difference D between the current (time t) focus position F _P (t) output from the imaging lens 1B and the focus position (previous focus position) F _P (t-t1) stored in the memory means M at the point in time t1 earlier (time t-t1).

In step S12, the focus operation switching means 53B determines whether the difference D calculated in step S11 is equal to or smaller than a preset threshold value T or not.
If the difference D is equal to or smaller than the threshold T (Yes in step S12), the focus control device 5B advances the operation to step S5. On the other hand, if the difference D is greater than the threshold T (No in step S12), the focus control device 5B advances the operation to step S13.

In step S13, the focus operation switching means 53B outputs an operation switching instruction to switch from MF to AF to the imaging lens 1B. This causes the imaging lens 1B to enter an AF operating state. In this way, when the difference D is greater than the threshold value T, the operation is quickly switched from MF to AF, thereby preventing the focus position of the imaging lens 1B from fluctuating significantly.
In step S14, the focus operation switching means 53B waits for a time t2 and continues the AF operation state. After the time t2 has elapsed, the focus operation switching means 53B executes the operations from step S10 onwards.

By performing the above operations, the focus control device 5B can switch the focus operation of the imaging lens 1B between AF and MF. At this time, the focus control device 5B switches from AF to MF when the difference between the focus position during MF operation and the focus position during AF operation becomes small, so that unintended focus movement can be suppressed.

<Operation knob movement>
With reference to FIG. 8, a schematic description will be given of the movement of the operation knob 41 of the MF operation unit 4 when switching from AF to MF in the case where the focus control device 5B is used.

Fig. 8(a) shows a state in which the imaging lens 1B is operating in AF mode, which is the same state as Fig. 5(a).
8B and 8C show an operation switching standby state after MF has been selected as the focus operation. When the operation is temporarily switched from AF to MF in the operation switching standby state, the focus position of the imaging lens 1B changes by a difference D=|F _P (t)-F _P (t-t1)| in the direction of the MF focus position indicated by the operation knob 41 during the passage of time t1.
As shown in Fig. 8B, even if MF is selected and the operation knob 41 is rotated, if the difference D is greater than the threshold value T, the focus operation switching means 53B continues to wait for the operation to be switched. Then, the imaging lens 1B switches from the MF operation to the AF operation by the operation of step S13 in Fig. 7. This AF operation continues for a time t2, and the operations of steps S1 to S12 in Fig. 7 are repeated again.

Then, as shown in FIG. 8C, when the difference D becomes equal to or smaller than the threshold value T, the operation switching state is completed, and the imaging lens 1B completely transitions to the MF focus operation.
At this stage, the focus position of the imaging lens 1B moves from the AF focus position to the MF focus position F _P (t), but the amount of movement is equal to or less than the threshold value T.
Then, as shown in FIG. 8D, by rotating the operation knob 41, the focus position F _{1 M} and the current focus position F _{1 P} are made to coincide with each other.

100 Imaging device 1, 1B Imaging lens 2 Camera body 3 AF (autofocus) operation section 4 MF (manual focus) operation section (focus demand)
41 Operation knob 5, 5B Focus control device 50 Focus operation selection means 51, 51B Threshold setting means 52, 52B Difference calculation means 53, 53B Focus operation switching means 54 Time setting means M Storage means

Claims (5)

A focus control device that can switch between an autofocus operation and a manual focus operation that operates at a focus instruction position corresponding to a rotation position of an operation knob, and controls switching of focus operations for an imaging lens that outputs a current focus position and the focus instruction position, comprising:
a difference calculation means for calculating a difference between the current focus position and the designated focus position;
a focus operation selection means for selecting either autofocus or manual focus in response to an instruction from an operator;
a focus operation switching means for instructing the imaging lens to perform the focus operation selected by the focus operation selection means,
the focus operation switching means instructs the imaging lens to perform the manual focus operation when the manual focus operation is selected by the focus operation selection means and the difference calculated by the difference calculation means becomes equal to or smaller than a preset threshold value. A focus control device that can switch between an autofocus operation and a manual focus operation that operates at a focus designation position corresponding to a rotation position of an operation knob, and controls switching of the focus operation for an imaging lens that outputs a current focus position, comprising:
a storage means for storing a focus position of the imaging lens at a preset time interval, and a difference calculation means for calculating a difference between a current focus position of the imaging lens and a focus position thereof before the preset time interval;
a focus operation selection means for selecting either autofocus or manual focus in response to an instruction from an operator;
a focus operation switching means for instructing the imaging lens to perform the focus operation selected by the focus operation selection means,
wherein, when the manual focus operation is selected by the focus operation selection means, the focus operation switching means instructs the imaging lens to switch between the manual focus operation and the autofocus operation for a predetermined duration, and terminates the switching between the focus operations when the difference during the manual focus operation becomes equal to or less than a predetermined threshold value. A focus control program for causing a computer to function as the focus control device according to claim 1 or claim 2. an autofocus operation unit that instructs the imaging lens to set a focus position by autofocus as an autofocus instruction position;
a manual focus operation unit that instructs the imaging lens to set a focus position corresponding to a rotation position of an operation knob as a manual focus instruction position;
the imaging lens that switches between an autofocus operation and a manual focus operation and moves a focus position to the autofocus instruction position or the manual focus instruction position;
a focus control device according to claim 1, which inputs a current focus position of the imaging lens and the manual focus instruction position and controls switching of a focus operation of the imaging lens;
An imaging device comprising: an autofocus operation unit that instructs the imaging lens to set a focus position by autofocus as an autofocus instruction position;
a manual focus operation unit that instructs the imaging lens to set a focus position corresponding to a rotation position of an operation knob as a manual focus instruction position;
the imaging lens that switches between an autofocus operation and a manual focus operation and moves a focus position to the autofocus instruction position or the manual focus instruction position;
a focus control device according to claim 2, which receives a current focus position of the imaging lens and controls switching of a focus operation of the imaging lens;
An imaging device comprising:

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