JPH0777648A - Lens control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize power saving when the lens is stopped in a lens control device using an actuator such as a stepping motor. A lens control device that is optimal for conditions that require high position accuracy, good speed response and drive response, and low power consumption, such as camera lens control So, the feature is,
A lens system having a lens group and a diaphragm, an actuator for moving the lens group, a driving means for driving the actuator, a lens position detecting means for detecting the position of the lens group, and a state of the diaphragm. And a control means for controlling the driving means based on the information obtained from the output of the aperture detection means to control the stop position of the lens group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the movement and position control of a lens, and particularly to the power saving of the lens control device while taking into consideration the optical characteristics of the lens system.

[0002]

2. Description of the Related Art In the field of consumer still cameras and video cameras, demands for miniaturization and weight reduction have been rapidly increasing in recent years, and accordingly small and high-performance lens systems have been steadily developed.

In the field of consumer video cameras, many rear focus type lens systems have been introduced into products in recent years, instead of the front lens focus lens which was mainstream until a few years ago, and lenses other than the front lens are used for focusing operation in recent years. Has been done. The front-lens focus type is a lens system that focuses on the lens closest to the subject, such as a DC motor for driving the large front lens, a reduction gear, and a cam ring for moving the variable-magnification lens and the compensator in conjunction. As a whole, it is inevitable that it will become larger. On the other hand, the rear focus type drives a light lens in the rear group, and thus does not require a reduction gear or the like and can use a small-sized actuator having a relatively small torque.

Further, by providing a focus lens behind the variable power lens, a competition function for correcting the displacement of the focal plane due to the variable power operation is added to the focus lens to eliminate the cam ring, and these are greatly reduced in size. It is well known that it has contributed.

On the other hand, in such a lens system, as an actuator for driving each lens,
In recent years, stepping motors have been widely used for reasons such as good speed response and drive response, high positional accuracy, and easy control.

The driving systems for these stepping motors include one-phase excitation and two-phase excitation depending on the application.
There are drive methods such as phase excitation and 1-2 phase excitation, which are used properly according to the object to be driven.

[0007]

However, when the stepping motor is used as the actuator as described above, when the lens is held at that position while stopped, a holding current is applied to the excitation phase at the stop position. I need to keep it flowing. This current itself may be a small value as compared with the time of driving, but if it is a direct current, and this state continues for a long time, power is consumed and heat is generated even if the lens is not driven. When using as a power source, it becomes a big problem.

In this respect, in the one-phase excitation, even if the current of the stepping motor is cut off in the stopped state, the magnetic poles of the rotor and the stator face each other, so that the stop position is caused by the magnetic force of the magnet of the rotor. Because it is retained
It is convenient, but since the rotation step angle of one step is large, it is not suitable for a lens that requires highly accurate positioning, such as a lens.

Further, in the two-phase excitation, the position accuracy is higher than that in the one-phase excitation because the two-phase excitation is stopped in the middle of the two phases. The holding current must be kept flowing. Therefore, there are the above-mentioned problems of power consumption and heat generation.

Further, in the 1-2 phase excitation, at the 1-phase stop position, the stop position can be held even if the current is interrupted, but the holding current is required at the 2-phase stop position. Even if these holding currents are reduced to the limit where the stop position of the stepping motor can be held, considering the use of battery power,
It cannot be ignored.

Therefore, whichever driving method is used,
It was impossible to realize satisfactory drive control.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and in particular, like the lens control of a camera, high position accuracy, good speed response and drive response, and An object of the present invention is to provide an optimal lens control device for conditions that require low power consumption, which is characterized by a lens system having a lens group and an aperture and a lens system for moving the lens group. Of the actuator, driving means for driving the actuator, lens position detecting means for detecting the position of the lens group, diaphragm detecting means for detecting the state of the diaphragm, and output of the diaphragm detecting means. Control means for controlling the drive means based on the information to control the stop position of the lens group.

[0013]

As a result, when it is not necessary to strictly control the stop position due to the depth of field and the like, even if the actuator such as the stepping motor is at the two-phase stop position, the range of the depth can be obtained. Rotate the stepping motor one step inside to stop at the position of one phase, and set the holding current to 0,
Further power saving can be realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens control device according to the present invention will be described in detail below in order with reference to the drawings.

FIG. 1 shows an example of the configuration of a camera system using a rear focus type lens, in which 101 is a fixed first lens group (hereinafter referred to as the front lens), and 102 is a second lens group that performs a zooming operation. Lens (hereinafter referred to as variable magnification lens),
Reference numeral 103 is a diaphragm, 104 is a fixed third lens group, 105 is a fourth lens group (hereinafter referred to as a focus lens) which has both a focusing function and a compensating function for correcting focus plane movement due to zooming, 106, 107, Reference numeral 108 denotes a position encoder for detecting the positions of the variable power lens 102, the diaphragm 103, and the focus compensation lens 105, respectively.
Reference numerals 09, 110, and 111 denote actuators for driving the variable power lens 102, diaphragm 103, and focus compensation lens 105, and 112, 113, and 114 denote drive energy for the variable power lens 102, diaphragm 103, and focus compensation lens 105, respectively. Driver to give
Reference numeral 115 is an image pickup device such as CCD, 116 is an amplifier, 117
Is a band-pass filter, 118 is a system control circuit composed of a microcomputer for controlling the focus and magnification of the lens, and 119 is an aperture of an appropriate amount for opening the diaphragm 103 so that the video signal level becomes constant at a predetermined value. It is a diaphragm control device for controlling the aperture.

The optical image information that has passed through the front lens 101, the variable power lens 102, the diaphragm 103, the fixed image-forming lens 104, and the focus competition lens 105 is the image pickup device 11.
Photoelectric conversion is performed by the amplifier 5, and the amplifier 11 is used as electrical image information.
6 to the bandpass filter (BPF) 117. The BPF 117 extracts only the high frequency component in the video signal whose level changes according to the focus state and transmits it to the system control circuit 118. The system control circuit 118 takes in the output signal of the BPF 117 by A / D conversion or the like. As is well known, the amount of high frequency components contained in the video signal when a subject is photographed increases as the subject approaches the in-focus state. Therefore, the system control circuit 118 sets the maximum value of the A / D conversion value. Cass Compensation 1
If the position of 05 is controlled, the focus operation can be automatically performed.

Next, the drive system including the actuators for driving each lens will be described step by step. FIG. 2 is a diagram showing an example of the configuration of an actuator for driving the focus competition lens 105 and a drive transmission system, in which an output shaft 702 of the actuator 111 is directly provided with a feed screw. The output shaft 702 is received by a bearing 703, and the bearing portion and the actuator are integrated by a member 701. 704 is a guide rod, and 702 is 111
When it is rotated by the guide rod 105, the guide rod 105 is prevented from rotating in a plane perpendicular to the optical axis, so that the rack 703 attached to the focus compensating lens 105 moves parallel to the optical axis, and accordingly. Lens 10
5 also moves parallel to the optical axis.

FIG. 3 shows the movement locus of the focus compensating lens for performing the focus surface correction while maintaining the focus when the magnification is changed by the rear focus lens, and the locus differs depending on the object distance. Further, when the moving speed of the variable power lens is constant, the moving speed of the focus compensating lens 105 does not change largely because the locus is almost linear in the vicinity of the middle area from the wide side, but the middle area in which the direction of inclination of the locus changes The focus compensating lens needs to be moved at a high speed because the trajectory is steeply decelerated in the vicinity and the trajectory becomes steep near the tele end through the almost stopped state. Furthermore, if the movement of the variable power lens and the movement of the focus compensator lens are not substantially coincident with each other, the trajectory deviates from the locus in FIG. 3 and blurring during the variable power operation becomes conspicuous.

Therefore, the actuator of the focus competition lens is required to have wide and accurate speed response, good drive response, and high position accuracy. A stepping motor can be cited as a suitable actuator that satisfies such conditions.

In the case of the configuration as shown in FIG. 2, normal driving cannot be performed unless the load of the actuator is lightened to some extent, but the focus compensating lens 105 in the rear focus lens system is relatively lightweight as described above. Even with the configuration using the stepping motor as shown in FIG. 2, it is possible to drive up to a rotation of about 500 pps without step-out.

In many actual products, a stepping motor is used as the focus compensating lens of the rear focus lens system.

Next, regarding the method of driving the stepping motor, generally, one of one-phase excitation, two-phase excitation, and one-two-phase excitation shown in FIGS. 4A, 4B, and 4C is used. It is classified as a drive system. The waveform on the right side of each table in FIG. 4 shows the phase relationship of the voltages applied to the terminals of the actuator. Actually, in order to remove noise, vibration, etc., it is not a rectangular wave like the excitation waveform of FIG. 4, but a trapezoidal wave with rising and falling slopes, or a waveform that rises or falls in a sine wave shape. However, the phase relationship does not change.

FIG. 5 shows how the rotor of the stepping motor rotates depending on the respective excitation methods. The stepping motor used here is A-Abar.
It has two coils of phase and B-Bbar phase, and the magnetic field generated from each coil is guided to the position shown in FIG.

In the case of one-phase excitation, as shown in FIG.
The magnetic pole of the rotor moves so as to always face the magnetic pole of the stator. That is, paying attention to the magnetic poles of the arrow rotor in FIG. 5, the Abar phase is N in the state of 1 in FIG. 5A, so that the S pole of the rotor arrow is in the Abar phase in (1) of FIG. 5A. Facing each other. In the state 2 of FIG. 4A, Bba
Since the r phase becomes N, the magnetic pole indicated by the arrow of the rotor moves to the Bbar phase in (2) of FIG. 5A. In other words, 18 ° rotation can be obtained by changing the magnetic pole once in the stator.

In the case of two-phase excitation, the magnetic field changes as shown in FIG. 4 (b), and the rotation of the rotor becomes as shown in FIG. 5 (b). At the time of two-phase excitation, the rotor moves so as to face the magnetic poles of the stator so as to face the middle of the magnetic poles, but it is the same as the one-phase excitation in that the rotor rotates 18 ° by one change of the magnetic poles.

In the 1-2 phase excitation, the 1-phase excitation and the 2-phase excitation are alternately repeated. Therefore, when the rotation starts from the position facing the magnetic pole of the stator, the magnetic pole of the stator is changed by the next change of the magnetic pole. The rotor moves so as to face the next magnetic pole due to the next change in the magnetic pole. As a result, 1
The amount of rotation obtained by changing the magnetic poles of the stator once is 9 °, which is 1/2 of one-phase excitation and two-phase excitation.

By the way, when a stepping motor is used and it is not necessary to move the lens while maintaining the current lens position, each excitation method shown in FIG.
A current will continue to flow through the motor coil so as to maintain the excitation phase at that time. Since the motor is not rotated, that is, the excitation phase does not change, this holding current is direct current. Since the load is only the coil, the magnitude of the holding current is several tens to several hundreds mA per coil,
Fever is also considerable.

FIG. 6 is a flow chart for current saving when the motor is stopped. By applying this control output to a drive circuit which will be described later, power consumption during stop can be reduced. You can In FIG. 6, when execution of processing is started in step 1001, step 302
Check to see if the stop command is output. If the stop command is not output, the counter N is cleared to 0 in step 303, the energy saving mode is released in step 1003, and the drive current can be supplied to the motor coil in step 304. When it is confirmed in step 302 that the lens stop command has been issued, in step 307 the drive pulse transmission is prohibited and the motor is stopped. In step 308, it is judged whether or not the value of the counter N exceeds a predetermined value (a certain threshold value 240 in FIG. 6), and if not, the counter is incremented in step 309 and the process returns to step 302. Step 308
If the counter value exceeds the predetermined value in step 100, step 100
The energy saving mode is set at 2 to suppress the energization amount. The counter N is provided to monitor whether or not the stopped state continues for a while, and the current is limited immediately after the stop, and when restarting immediately, the current is limited to facilitate the restart. I tried not to take it.

By performing the above processing, if there is a high possibility that the stopped state will continue for a while after entering the stopped state and the stopped state is likely to continue, the energization amount to the motor is suppressed in the stopped state to Savings and heat generation can be suppressed. The case where the process of FIG. 6 is applied to each of FIGS. 5A, 5B, and 5C will be described below.

In the case of the one-phase excitation shown in FIG. 5A, even if the holding current is not supplied when the motor is stopped, the magnetic poles of the rotor and the stator always stop facing each other.
It is possible to prevent the rotor, which is a permanent magnet, from attracting the metallic stator to some extent and rotating the rotor. or,
At least in the structure shown in FIG. 2, even if a force for rotating the rotor by moving the lens parallel to the optical axis is applied, the rotor must be mechanically structured so that the force is not so large. Can not be rotated.

FIG. 7 shows that when the motor is rotated by one-phase excitation,
1 shows a configuration of a motor drive system having a function of cutting off power supply to a motor in a stopped state. In FIG. 7, reference numeral 401 denotes a drive control circuit that outputs an excitation pattern to the motor driver. If applied to FIG. 1, the drive pulse is sent by the system control circuit 118, and the drive current according to the drive pulse is supplied. The output is the driver 112 or 1
14 is executed. 402 and 403 are A-Ab, respectively
ON / OF energization of ar phase and B-Bbar phase coils
F switch, 404 is a switch control circuit for controlling those switches, and 202 and 209 are A-Ab.
ar, B-Bbar phase H bridge circuit, 203, 21
Reference numeral 0 is an A-Abar phase coil and B-Bbar phase coil, respectively, and 216 is a power source.

The switch control circuit 404 of FIG. 7 controls the switches 402 and 403 according to the flow chart of FIG. 8, and cuts off the power supply to the coil when stopped. The process of FIG. 8 is designed to be executed in response to the process of FIG.
The motor drive / stop command is output in the system control circuit 118, and the switch control circuit 404 is also included in the system control circuit 118. When the execution of the process is started in step 801 of FIG. 8, it is confirmed in step 802 whether the motor stop command is output. If the motor is not stopped, step 805 switches 402,
403 is closed so that the drive current can be passed.
If it is confirmed in step 802 that the motor has stopped, it is confirmed in step 803 whether an energy saving command is output. The energy saving instruction is step 100 in FIG.
It is output at 2. If the energy saving command is not output at step 803, the switch is closed at step 805, but if the energy saving command is output, the switches 402 and 403 are opened at step 804 to cut off the power supply to the motor.

By performing the above processing, it is possible to realize power saving during stoppage during one-phase excitation.

Next, consider the case of two-phase excitation. Figure 5 (b)
As shown in (2), in the two-phase excitation, the magnetic pole of the rotor always stops facing the middle of two adjacent magnetic poles of the stator. If the energization to the stator coil is interrupted in the stopped state like the one-phase excitation, the rotor will be opposed to either the left or right stator by 1/2 step due to the assembly error of the magnetic pole of the stator and the slight deviation of the stopped position. It is predicted that it will move by minutes. That is, in the case of two-phase excitation, it is necessary to excite the stator even in the stopped state. In other words, in the case of two-phase excitation, a current sufficient to secure a magnetic field that holds the rotor at the stop position must be supplied even during the stop.

Therefore, the amount of current in the stopped state can be suppressed by the circuit as shown in FIG. In FIG.
Reference numeral 1201 denotes a drive control circuit for sending the excitation pattern to the motor driver. If applied to FIG. 1, the system control circuit 118 sends the excitation pattern and outputs the drive current according to the excitation pattern to the driver 112 or 114.
Will be done in. 1202 is a system control circuit 118
Switch control blocks 1203 and 1204, which control the switches 1203 and 1204, are switches that are controlled by the switch control block 1202 so as to fall to 1 when the motor is driven and to 2 when the motor is stopped.

The control of the switch control block 1202 is executed according to the flow chart of FIG.
The process is executed in response to the process result of FIG. In FIG. 10, when the execution of processing is started in step 1301,
At step 802, it is confirmed whether a stop command has been output. If the stop command is not output, the switch 12 is activated to energize the motor coil in step 1303.
03 and 1204 are grounded. If it is confirmed that the motor is stopped in step 802, it is confirmed whether or not the energy saving instruction is output in step 803. If the energy saving instruction is not output, the power supply to the motor is enabled in step 1303, and the energy saving instruction is output. If so, in step 1302, the switch is tilted to the position where the switch is installed via a resistor so that only the holding current is flown while suppressing energization.

The power-saving motor drive circuit for 1-2 phase excitation shown in FIG. 5C is as shown in FIG.

In FIG. 11, reference numeral 201 denotes a drive control circuit for outputting an excitation pattern to the motor driver.
The system control circuit 118 outputs the drive pulse, and the driver 112 or 114 outputs the drive current according to the drive pulse. Reference numerals 204 and 211 denote switches for switching the energization amount to the coils of A-Abar phase and B-Bbar phase, respectively, and 215 is a switch control circuit for controlling those switches. Also, 215 and 2
Reference numeral 01 is connected by a communication path 217, and reference numeral 215 makes it possible to know whether the excitation state of the motor at that time is two-phase or one-phase.

The control of 201 is performed by the processing according to the flowchart of FIG. In FIG. 12, when the execution of processing is started in step 901, step 8
At 02, it is determined whether or not a stop instruction is output. If the stop command is not output, step 905
Then, the switches 204 and 211 are grounded so that a drive current can be supplied to the motor coil. When it is confirmed in step 802 that the motor has stopped, it is confirmed in step 803 whether the energy saving command is output. If the output of the energy saving command is not confirmed, the energization permitted state is maintained in step 905. After confirming the output of the energy saving command in step 803, it is confirmed in step 902 whether the current stop position is the two-phase stop position. If it is in the two-phase stop position, the switch is set through a resistor in step 904, and a current sufficient to hold the current motor position is supplied. Further, in step 902, the two-phase stop position is not set,
That is, when it is determined that the position is the one-phase stop position, the switch is opened in step 903 to cut off the energization.

Energy saving can be achieved by distinguishing the two-phase stop position from the one-phase stop position and changing the method of limiting the amount of current as described above.

The driving method of the stepping motor has been specifically described above. However, according to these driving means, when it is stopped at the two-phase stop position, it is smaller than that at the time of driving, but is held by the motor coil. Since it is necessary to supply current,
Although the amount of current is limited by inserting a resistor, the amount of power consumption is not negligible compared to when the current is cut off.

In other words, when stopped in two phases, A-
It is necessary to supply a holding current to both the Abar and B-Bbar coils. Even if the holding current is reduced to 1/2 of the usual amount per coil, if the energization amounts of the two coils are combined, the amount of current flowing through one ordinary coil will be equal. Also, if the amount of holding current is made extremely small,
The original purpose of retention cannot be achieved.

Therefore, the following embodiment of the present invention can solve the above-mentioned problems. If it is not necessary to strictly control the stop position due to the depth of field of the optical element and the like, it is assumed that two-phase operation is performed. Even if the stop position is the correct stop position, the one-step motor is rotated to stop at the one-phase position, the holding current is set to 0, and further power saving is realized.

The embodiment will be described below with reference to FIGS. 1 and 11 to 14.
Will be explained.

FIG. 13 is a flow chart of an embodiment having a characteristic control operation of the present invention. The entire system configuration in this embodiment is as shown in FIG. 1, and the drive system relating to energy saving measures itself. The configuration is similar to that of FIG. 11, and the drive method is the 1-2 phase excitation method.

The process of FIG. 13 is executed in the switch control circuit 215 as described above, and the switch control circuit 215 is executed.
Are included in the system control circuit 118.

When the execution of the processing is started in step 301 of FIG. 3, it is confirmed in step 302 whether the motor stop command is output. When the motor stop command is not output, the counter N is cleared to 0 at step 303, and the switches 204 and 211 are grounded so that the focus motor can be driven at step 304.

When it is confirmed that the stop command is output in step 302, it is confirmed in step 305 whether the stop command has already been output and the addition period of the counter N has started. If the motor has stopped in response to the stop command and the process of step 305 has been executed for the first time without the counter N addition period, the process proceeds to step 306, and the counter N counting period is entered. If there is, the process proceeds to step 308.

At step 306, the state of the diaphragm is confirmed. The state of the diaphragm can be grasped by the system control circuit 118 via the encoder 107. FIG. 14 shows that when the maximum permissible circle of confusion diameter in the range where blur cannot be recognized on the imaging surface is constant, the defocus amount that causes this maximum permissible circle of confusion is converted into the focus lens movement amount, and this focus amount is changed. The amount of movement of the lens is replaced by the stepping pulse number of the stepping motor and is displayed for each aperture value. This number of pulses is the number of pulses in the 1-2 phase excitation method. Therefore, in terms of the number of pulses in Fig. 14, ±
Blurring that exceeds the permissible circle of confusion does not occur even if moving by two pulses or more. With an aperture value of F = 4.0 or more, blurring cannot be confirmed even if the lens is stopped at the one-phase position next to the correct two-phase stop position. It will be. Therefore, in step 306, Fn
o. Check if is over 4.0.

When F = 4.0 or more, the focus motor is stopped in step 312, and when the stop position is the two-phase stop position in step 313, step 314 sets 1
Only the pulse is advanced, the motor is moved to the one-phase stop position, the motor is stopped in step 307, and the process of step 308 is started.

When it is determined in step 306 that F is less than 4.0, the motor is stopped in step 307, and the counting of the counter for entering the power saving mode is started in step 308. Until the counting of the counter is completed, step 309 → step 302 → step 305 → step 3
The processing of 08 is cycled, and the process waits until the counter value exceeds the predetermined value.

When it is determined in step 308 that the value of the counter N has exceeded the predetermined value, step 310 determines whether the current stop position is the 2-phase position or the 1-phase position, and if it is the 2-phase stop position, step 311 is executed. Switch 204 and 211 are installed via a resistor, and if the one-phase stop position is set, step 315 is performed.
Then, the switches 204 and 211 are directly grounded.

By performing the above-described processing in the above-described configuration, the motor will always stop at the one-phase stop position if at least the depth of field becomes deep. At that time, the motor is energized. It becomes possible to cut off and carry out energy saving.

In the case of the optical system shown in FIG. 1, since there is a lens for focus adjustment on the imaging surface side of the variable power lens, the depth change due to the position of the variable power lens is an amount that can be almost ignored. . Therefore, in this embodiment, attention is paid only to the depth change due to the aperture value. FIG. 14 shows a two-dimensional table when the depth changes depending on the position of the variable power lens, but it goes without saying that the technical idea of the present invention can be used as it is.

Further, the above embodiments need not be limited when using the autofocus function. Even in the manual focus adjustment, if the depth is deep, even if the stop position is only the one-phase position, the photographer will not feel any discomfort, and thus the function can be used in any adjustment means.

[0056]

As described above, according to the present invention,
The condition that the stepping motor stops at the two-phase stop position is narrowed down only to the shallow depth part, and at the other parts it is stopped at the one-phase position, so when the motor is stopped in actual use. Opportunities to create the need for holding current have become limited at shallow depths. In other cases, since the depth is deep, blurring is not recognized even when the motor is stopped at the one-phase position, and the power supply to the motor can be cut off at that time.

Therefore, the power consumption can be reduced as compared with the conventional case without degrading the accuracy of focusing.

[Brief description of drawings]

FIG. 1 is a block diagram of a lens control device according to the present invention.

FIG. 2 is a diagram showing a structure of a focus lens drive system.

FIG. 3 is a characteristic diagram showing a change of a focus surface that changes according to a zooming operation in an inner focus lens.

FIG. 4 is a diagram showing the relationship between the magnetic poles of each phase of the stepping motor and the drive current waveform.

5 is a diagram showing a positional relationship between a rotor and a stator corresponding to the relationship between the drive current waveform and the magnetic poles in FIG.

FIG. 6 is a flow chart for explaining a power saving mode when the stepping motor is stopped.

FIG. 7 is a diagram showing a configuration of a drive control circuit in a one-phase excitation drive system.

FIG. 8 is a flow chart for explaining the operation of the drive control circuit of FIG.

FIG. 9 is a diagram showing a configuration of a drive control circuit in a two-phase excitation drive system.

10 is a flowchart for explaining the operation of the drive control circuit of FIG.

FIG. 11 is a diagram showing a configuration of a drive control circuit in a 1-2 phase excitation drive system.

12 is a flowchart for explaining the operation of the drive control circuit of FIG.

FIG. 13 is a flow chart showing the operation of the stepping motor drive control circuit in the present invention.

FIG. 14 is a diagram showing a data table for explaining the operation of the stepping motor drive control circuit in the present invention, in which the depth of field is converted into the number of stepping step pulses of the stepping motor.

Claims (2)

[Claims] 1. A lens system having a lens group and an aperture, an actuator for moving the lens group, a drive unit for driving the actuator, an aperture detection unit for detecting a state of the aperture, and an aperture detection. And a control unit that controls the driving unit according to the information obtained by the unit and controls the stop position of the lens group. 2. A lens group, an actuator for moving the lens group, a driving means for driving the actuator, a detecting means for detecting a depth of field, and the driving based on an output of the detecting means. And a control means for controlling the stop position of the lens group.