JP2020052400A - Zoom control device and control method thereof - Google Patents

Abstract

To provide a zoom control device capable of ensuring focus on a particular subject even when zooming and a control method thereof.SOLUTION: The zoom control device is configured to display a display that indicates the optical zoom position for focusing on a specific subject even when in a state out of focus on a specific subject on the basis of the defocus amount acquired for a focus detection area corresponding to the specific subject.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a zoom control device and a control method thereof.

  The zoom lens is widely used in an optical device represented by an imaging device because the angle of view can be continuously changed without changing the lens. However, in the zoom lens, a focusable distance range, in particular, a focusable shortest distance (shortest shooting distance) changes according to an angle of view (focal length). Therefore, for example, when zooming to the telephoto end while focusing on the shortest photographing distance at the wide-angle end, focusing is stopped halfway. Blurring of an image during zooming is a problem particularly when shooting a moving image.

  Patent Document 1 discloses that a focusable distance range (a range of a distance to a subject) is displayed by a numerical value or an index according to a current focal length of a zoom lens, so that a subject at a non-focusable distance is displayed. There is described a camera device for preventing a user from performing a focusing operation.

JP 2006-47602 A

  The technique described in Patent Literature 1 shows a focusable distance range, and does not consider a focusable zoom magnification range. In Patent Literature 1, it is impossible to know how far a subject that is not currently focused can be focused even when zoomed up.

  The present invention has been made in view of the above circumstances, and has as its object to provide a zoom control device and a control method thereof that suppress a situation in which a specific subject cannot be brought into focus by zooming.

  The above object is achieved by an obtaining unit that obtains a defocus amount for a focus detection area corresponding to a specific subject, a control unit that controls optical zoom according to a zoom instruction, and a defocus amount that is obtained by the obtaining unit. A display that controls the display means to display, on the display means, a limit position that is a limit optical zoom position at which a specific subject can be focused even when the specific subject is not focused. Control means, and a zoom control device.

  According to the present invention, it is possible to prevent a specific subject from being unable to be focused by zooming.

FIG. 1 is a block diagram illustrating a functional configuration example of an imaging device to which a zoom control device according to an embodiment of the present invention has been applied. Diagram showing the relationship between the position of the focus lens and the position of the zoom lens that focus on the same subject distance Flowchart regarding display operation of limit zoom magnification in the first embodiment FIG. 6 is a diagram illustrating a display example of a limit zoom magnification according to the first embodiment. Flowchart for zoom control operation in the second embodiment

  The present invention will be described in detail based on exemplary embodiments with reference to the accompanying drawings. Here, an embodiment in which the zoom control device according to the present invention is applied to an imaging device such as a digital camera will be described. However, the present invention is applicable to any electronic device capable of instructing zoom up (zoom in) and zoom down (zoom out) of a zoom lens. Such electronic devices include digital (video) cameras, surveillance or observation camera systems, camera intercom systems, as well as computer devices, mobile phones, game consoles, robots, drones, and drive recorders. Further, a photographing function is not essential, and the present invention can be applied to a telescope, a microscope, and the like. In the following, what is described as a subject is not an object to be photographed but an observation object within an angle of view in an apparatus such as a telescope or a microscope having no photographing function. The systems and devices listed here are merely examples, and do not limit the scope of the present invention.

<First embodiment>
<Apparatus configuration>
FIG. 1 is a block diagram illustrating a functional configuration example of an imaging device 100 according to an embodiment of the present invention. The lens unit 101 includes a first fixed lens 102, a variable power lens 103, an aperture 104, a second fixed lens 105, a focus lens 106, a variable power lens driving unit 107, and a focus lens driving unit 108. The lens unit 101 may include another lens such as an anti-vibration lens. Each of the first fixed lens 102, the variable power lens 103, the second fixed lens 105, and the focus lens 106 is composed of one or more lenses. The lens unit 101 is a zoom lens with a variable focal length, and may be integrated with the imaging device 100 or may be an interchangeable lens that is detachable from the main body of the imaging device 100.

  Among the lenses included in the lens unit 101, the variable power lens 103 and the focus lens 106 are configured to be movable within a predetermined range in the optical axis direction. The variable power lens driving unit 107 realizes an optical zoom function of moving the variable power lens 103 in the optical axis direction and optically changing the focal length of the lens unit 101. Further, the focus lens driving unit 108 moves the focus lens 106 in the optical axis direction to adjust a subject distance at which the lens unit 101 focuses, and a correction function to correct a focal plane shift accompanying optical zoom. To achieve.

  Each of the variable-magnification lens driving unit 107 and the focus lens driving unit 108 has an actuator (a stepping motor, a DC motor, a vibration motor, a voice coil motor, and the like) for driving a lens to be driven. The variable-magnification lens driving unit 107 and the focus lens driving unit 108 also have a circuit (such as a sensor) for detecting the position of the lens to be driven.

The transmission mirror 125 splits the light beam into two, and can form the image on the image sensor 109 and the distance measurement sensor 126.
The distance measurement sensor 126 is, for example, a phase difference sensor, and divides the incident light beam into two, forms an image on the phase difference sensor, and determines the direction and amount (defocus amount) of defocus from the interval between the two images. You can ask. The system control unit 114 controls the focus lens driving unit 108 to move the focus lens 106 from the current position and the direction based on the defocus amount, and to perform automatic focus detection (autofocus, AF) using the phase difference detection method. To achieve.
The transmission mirror 125 and the distance measurement sensor 126 may be included in the lens unit 101, or may be a so-called mount adapter mounted between the imaging device 100 and the lens unit 101.

  The image sensor 109 is, for example, a CCD image sensor or a CMOS image sensor, and includes a plurality of two-dimensionally arranged pixels and a vertical and horizontal scanning circuit for converting electric charges accumulated by a photoelectric conversion unit included in the pixels into a voltage and reading the voltage. It has a timing generator and the like. The image sensor 109 converts an optical image of the subject formed by the lens unit 101 into a group of electric signals by a plurality of pixels and outputs the group as an analog image signal. Note that the imaging element 109 may have an A / D conversion function.

  Note that the imaging element 109 of the present embodiment has one microlens for each pixel and two photoelectric conversion units divided in the horizontal or vertical direction. Then, a signal can be read for each photoelectric conversion unit.

  The image signal read from the image sensor 109 is input to the image processing unit 110. The image processing unit 110 applies image processing such as A / D conversion, noise suppression, white balance adjustment, pixel interpolation (demosaicing), resize, color conversion, gradation correction, encoding, and decoding to an image signal. . Further, the image processing unit 110 may apply processing such as detection, recognition, and tracking of an area including a specific subject such as a face or a human body to the image data. The image processing unit 110 outputs the image data to which the processing has been applied to the memory control unit 111. The memory control unit 111 stores the image data in the memory 112.

  Further, the image processing unit 110 can generate an evaluation value used for automatic focus detection (AF) and automatic exposure control (AE) from the image data and supply the evaluation value to the system control unit 114. Using these evaluation values, the system control unit 114 can execute AF and / or AE processing. For example, the image processing unit 110 acquires a signal group of one photoelectric conversion unit and a signal group of the other photoelectric conversion unit based on signals read from a plurality of pixels, and generates a pair of image signals. The image processing unit 110 obtains the defocus amount of the lens unit 101 from the pair of image signals, and outputs the defocus amount to the system control unit 114 as an AF evaluation value. The system control unit 114 controls the focus lens drive unit 108 to move the focus lens 106 in a direction and an amount based on the defocus amount and from the current position, thereby realizing a phase difference detection type automatic focus detection (AF). . That is, the system control unit 114 can perform so-called imaging plane phase difference AF. Details of the imaging surface phase difference AF are disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-28397.

  Alternatively, the image processing unit 110 can generate a contrast evaluation value for an image signal obtained from the imaging element 109 and output the contrast evaluation value to the system control unit 114 as an AF evaluation value. The system control unit 114 controls the focus lens driving unit 108, acquires contrast evaluation values for a plurality of positions of the focus lens 106, and searches for a position of the focus lens 106 at which the contrast evaluation value is maximum. Thereby, the system control unit 114 can also realize a contrast AF.

  The image processing unit 110 also implements an electronic zoom function by extracting or enlarging a part of the image. The image processing unit 110 implements an electronic zoom function by extracting a partial area of the image data stored in the memory 112 based on an instruction from the system control unit 114, and further applying an enlargement process as necessary. be able to. Note that a smooth electronic zoom effect can be obtained by gradually enlarging or reducing the size of the region to be extracted for each frame.

  The memory control unit 111 controls access to the memory 112. The memory 112 is used to store image data to be processed by the image processing unit 110, image data being processed, processed image data, image data to be displayed on the display unit 113, and the like. The memory 112 has a recording capacity capable of storing moving image and audio data for a predetermined period of time and its accompanying data (such as coordinates). The memory 112 also serves as a frame buffer for OSD display and a frame buffer for image display. The system control unit 114 or the image processing unit 110 converts image data of GUI parts such as icons stored in the non-volatile memory 117 and image data representing set values and various information into an OSD display of the memory 112. Write to a predetermined position in the frame buffer. By displaying a video signal of an image obtained by combining the contents of the frame buffer for image display and the contents of the frame buffer for OSD display on the display unit 113, for example, GUI parts and setting values are superimposed on a moving image being shot. The display is made.

  The display unit 113 has a display device such as an LCD, generates a video signal from data stored in the frame buffer of the memory 112, and displays the video signal on the display device. The display unit 113 may be a touch display having a touch panel function. By sequentially displaying the moving image on the display unit 113 while capturing the moving image, the display unit 113 can function as an EVF. Although there is no particular limitation on the information that can be displayed on the display unit 113, the optical zoom magnification of the variable power lens 103, the focal length of the lens unit 101, the AF frame indicating the focus detection area, and the focusable distance range described later There is a GUI shown. The display may be performed separately from the display unit 113 or instead of the display unit 113, for example, on an external display device that can communicate via the external I / F 123. In this case, the data to be transmitted to the external display device may be display image data or a video signal.

  The nonvolatile memory 117 may be an electrically erasable / recordable EEPROM or the like. The non-volatile memory 117 stores a program executed by the system control unit 114, constants necessary for executing the program, set values, GUI data, unique information of the imaging apparatus 100, and the like.

  The system control unit 114 has at least one programmable processor or at least one circuit. The system control unit 114 controls the operation of each unit of the imaging apparatus 100 and the connected external device by loading the program recorded in the nonvolatile memory 117 into the system memory 116 and executing the program. The system control unit 114 realizes the zoom control device according to the present embodiment. The system memory 116 is, for example, a RAM, and stores a program executed by the system control unit 114 and constants, variables, and the like for executing the program. The system memory 116 and the memory 112 may be different areas in the same memory space. The system timer 115 acquires the time of the internal clock and measures the elapsed time.

  The power control unit 118 includes a battery detection circuit, a DC-DC converter, a switch circuit for switching a block to be energized, and the like. The power supply control unit 118 detects information about the power supply unit 119, such as the mounting state of the battery and the AC adapter, the type of battery, and the remaining battery level. In addition, the power supply control unit 118 controls the DC-DC converter based on the detection result regarding the power supply unit 119 and the instruction of the system control unit 114, and controls a power supply destination, a supply voltage, and the like. The power supply unit 119 may be a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, a Li battery, or an AC adapter.

  The operation unit 120 is a general term for an input member that receives an operation from a user. Representative input members of the operation unit 120 include, but are not limited to, buttons, keys, dials, touch sensors, levers, slide switches, joysticks, and rotating rings. The input member of the operation unit 120 is used as a menu button, a direction key, an enter button, a return (cancel) button, a shutter button, a moving image shooting button, a power switch, and the like according to the assigned function.

  The zoom lever 121 and the touch panel 122 are examples of operation members included in the operation unit 120. The zoom lever 121 is a lever to which a function of inputting a magnification change instruction of the lens unit 101 is assigned. The touch panel 122 may be provided on the display unit 113, for example, or may be provided separately from the display unit 113. The system control unit 114 can detect the coordinates of one or more positions where the object touches (or approaches) the touch panel 122. Therefore, the touch panel 122 can realize a so-called software switch in combination with an image displayed on the display unit 113. Further, the system control unit 114 can recognize a touch operation (gesture) such as a tap, a slide, and a pinch on the touch panel 122 based on a change in a position where an object is in contact with the touch panel 122 or a change in a contact state. Then, various functions can be assigned to the recognizable touch operation and / or a combination thereof.

  When the operation of the input member included in the operation unit 120 is detected, the system control unit 114 controls each unit to realize the function assigned to the operation at that time. For example, when a button (menu button) to which a menu display function is assigned is pressed, the system control unit 114 causes the display unit 113 to display a menu screen for performing various settings. The user can make various settings using the direction button, the enter button, the return button, and the like while looking at the menu screen.

  In addition, it is possible to appropriately determine to which input member a certain function is assigned. For example, here, the input function of the zoom instruction is assigned to the lever, but it may be assigned to a dial or ring that can rotate in two directions. The ring may be an input member that is formed to be rotatable, for example, along the outer periphery of the lens unit 101, and that can detect the amount of rotation, the rotation direction, and the rotation speed by the system control unit 114. Further, the zoom-in instruction input function and the zoom-out instruction input function may be assigned to separate input members. Further, a slide switch realized by combining the touch panel 122 and the display on the display unit 113 or a specific gesture (for example, a slide operation in a specific direction) on the touch panel 122 may be assigned a zoom-in and zoom-out instruction input function. Further, the operation amount and operation speed of the input member may be associated with the zoom-in and zoom-out speed.

  The external I / F 123 is an interface for connecting the imaging device 100 to an external device by wire or wirelessly. For example, one or more interfaces conforming to various standards such as HDMI (registered trademark), LANC (registered trademark), USB, wireless LAN, and Bluetooth (registered trademark) may be used. Alternatively, it may be an input / output interface for a composite video signal.

  The system control unit 114 controls each unit based on a signal or a command received from an external device communicable via the external I / F 123, thereby enabling the external device to remotely control the imaging apparatus 100. The functions that can be remotely controlled include a zoom function of the lens unit 101. Further, the system control unit 114 outputs display image data stored in a frame buffer in the memory 112 or a video signal based on the display image data to an external device through the external I / F 123, and displays a screen display described later in the external device. Can be realized. The external I / F 123 also includes an interface for connecting the imaging device 100 and the lens unit 101 by wire or wirelessly.

  In addition, a pointing device such as a mouse or a track pad can be connected to the external I / F 123. In this case, the connected pointing device can be treated as one of the input devices of the operation unit 120. For example, when a pointing device is connected to the external I / F 123, the system control unit 114 includes a mouse cursor in the display image. Then, the system control unit 114 can execute an operation according to the position of the mouse cursor when a click or a tap operation is detected.

  The recording medium 124 is used as a recording destination of data such as still images and moving images (and audio) obtained by shooting. The recording medium 124 may be a medium that can be removed from the imaging device 100 such as a memory card, or a medium that cannot be removed from the imaging device 100 such as a part of the nonvolatile memory 117. The still image data and the moving image data recorded on the recording medium 124 are once read into the memory 112, decoded by the image processing unit 110 as necessary, and then displayed on the display unit 113.

<Operation area of zoom lens and focus lens>
FIG. 2 is a diagram illustrating the relationship between the position of the focus lens 106 and the position of the variable power lens 103 (the focal length of the lens unit 101) when the lens unit 101 focuses on a plurality of subject distances. The horizontal axis indicates the movable range of the variable power lens 103. The position of the zoom lens 103 where the focal length of the lens unit 101 is minimum (the angle of view is maximum) is at the wide angle end, and the zoom lens 103 where the focal length of the lens unit 101 is maximum (the angle of view is minimum). Is the telephoto end. The vertical axis indicates the movable range of the focus lens 106, and the movement limit in the direction of decreasing the focusing distance of the lens unit 101 is the closest end, and the movement limit in the direction of increasing the focusing distance of the lens unit 101 is infinite. It is.

  L1 to L5 indicate combinations of the focus lens position where the lens unit 101 focuses and the position of the variable power lens 103 when the subject distance is infinity, 1 m, 70 cm, 40 cm, and 1 cm, respectively. As for L1 and L2, solid lines exist in the entire movable range of the variable power lens 103. This indicates that a subject in a distance range from infinity to 1 m can be focused regardless of the angle of view (focal length). That is, a subject in a range of distance from infinity to 1 m can be kept in focus at any angle of view.

  On the other hand, in L3 to L5, the solid line is interrupted before the telephoto end. This means that, when the subject distance is 70 cm or less, the subject is focused at the wide-angle end, and when the subject is continuously zoomed up, the subject is blurred in the middle. However, when the subject distance is 70 cm, there is a focusable range near the telephoto end. Here, the position range of the variable power lens 103 (the range of the focal length of the lens unit 101) where the solid line is interrupted is referred to as a defocus area.

  Also, the position of the zoom lens 103 corresponding to the wide-angle end of the defocus area, the minimum value of the zoom magnification at which focusing cannot be performed at the same distance, or the maximum that can maintain the state of focusing at the same distance during enlarged zooming from the wide-angle end Is called the minimum limit zoom magnification. The minimum limit zoom magnification (the limit position of zoom-in) is a defocus area before entering the defocus area during optical zoom drive (during zoom-in drive) from a zoom position that can maintain a focused state on the subject to be measured. Is the optical zoom position at the boundary with.

  Further, the position of the variable power lens 103 corresponding to the telephoto end of the defocus area, the maximum value of the zoom magnification at which focusing cannot be performed at the same distance, or the state where focusing is performed at the same distance during reduced zooming from the telephoto end can be maintained. The minimum zoom magnification is called the maximum limit zoom magnification. The maximum limit zoom magnification (the limit position of the zoom-out) is determined before the defocus area is entered during the optical zoom drive (during the zoom-out drive) from the zoom position at which the in-focus object can be maintained. This is the optical zoom position at the boundary with the focus area.

  In the example of FIG. 2, the maximum limit zoom magnification exists only in the case of L3 (object distance 70 cm). Further, the minimum limit zoom magnification and the maximum limit zoom magnification for a certain subject distance are collectively referred to as a focus limit zoom magnification (limit position). When there is no maximum limit zoom magnification, the minimum limit zoom magnification and the focusing limit zoom magnification are the same.

  Note that information indicating the relationship shown in FIG. 2 can be stored in the nonvolatile memory 117, for example. For example, the in-focus subject distance can be stored for each combination of the position of the variable power lens 103 and the position of the focus lens 106. Alternatively, a function for calculating the subject distance using the position of the variable power lens 103 and the position of the focus lens 106 as variables may be stored. It may be stored in another way.

<Display of minimum / maximum limit zoom magnification>
Next, a display control operation of the limit zoom magnification performed by the system control unit 114 will be described with reference to a flowchart of FIG. The display control operation described below is implemented by loading a program stored in the nonvolatile memory 117 into the system memory 116 and executing the program by the system control unit 114. Note that “zoom magnification” in the following description can be read as “position of the zoom lens 103” or “focal length of the lens unit 101”.

  The display control operation shown in FIG. 3 can be executed in a state where a live view (LV) image is displayed on the display unit 113 (and / or the external display device) (during standby for shooting and during recording of a moving image). For example, it may be executed in another state according to the user setting.

  When the imaging apparatus 100 is started, the system control unit 114 executes an operation in a shooting standby state. In the shooting standby state, the system control unit 114 performs imaging by the imaging element 109, causes the image processing unit 110 to generate display data, sequentially stores the display data in the memory 112, and displays a live view image on the display unit 113.

  The user sets the operation conditions in this flowchart in advance by selecting a desired item from a menu screen (not shown), or by specifying a desired coordinate position using the touch panel 122 or the like included in the operation unit 120.

  In S101, the system control unit 114 determines a method for measuring the subject distance. In the present embodiment, it is assumed that the subject distance is measured using the same distance measurement function as that used in the AF function of the imaging apparatus 100. As described above, in the present embodiment, the AF functions of the phase difference detection method and the contrast detection method can be realized based on the image signal obtained using the image sensor 109. Further, an AF function of a phase difference detection method using the distance measurement sensor 126 can be realized. Therefore, in step S101, the system control unit 114 determines which AF distance measurement function is used to measure the subject distance. There is no particular limitation on the determination method. For example, the determination method can be determined according to a set value that can be changed by the user. Note that when there is only one available method of measuring the subject distance or when a predetermined measurement method is determined to be used, S101 may not be performed.

  Note that the method of measuring the subject distance is not limited to the above-described AF distance measurement function, and any method capable of detecting the distance between the subject and the image sensor 109 can be used. For example, a method of measuring a subject distance based on a defocus amount using a dedicated sensor (line sensor) provided for AF of a phase difference detection method, a reception time of a reflected wave by irradiating ultrasonic waves or infrared rays, or the like. For example, a method of measuring the subject distance based on the distance may be used. Moreover, you may measure by combining a some method. A configuration in which the subject distance is measured using an external device and the measured value is obtained through the external I / F 123 may be employed. In the present embodiment, a method for detecting a distance based on the defocus amount will be described.

  In S102, the system control unit 114 determines a target subject for distance measurement. The determination of the subject may be to determine a partial area of the live view image displayed on the display unit 113 as the subject area. For example, the system control unit 114 can determine a region of a predetermined size centered on a position in an image specified by the user through the touch panel 122 or the like as a subject region. The user can designate a plurality of subjects as subjects for distance measurement. When a subject to be measured for distance is specified, a corresponding focus detection area is set, and a defocus amount is obtained.

  Alternatively, the system control unit 114 may determine a region of a predetermined size centered on a specific position (for example, the center) of the image as a subject region without user input. In the manual focus mode, an area in the focus guide frame that displays the degree of focus of the object in the frame may be determined as the object area. In addition, the system control unit 114 may determine a region of a predetermined size from the currently focused region as the subject region.

  When the image processing unit 110 detects a specific characteristic region (for example, a person's face region) from an image, the system control unit 114 may determine the characteristic region detected by the image processing unit 110 as a subject region. . Further, the system control unit 114 may determine one area as a subject area from a plurality of predetermined options (for example, a settable AF frame) according to the user or other conditions. If there is a limit on the position of the subject area that can be selected by the distance measurement method, the system control unit 114 determines the subject area in consideration of the limitation. Note that the number of subject areas determined here may be plural. The subject area may be the same area as the AF target area (that is, the main subject area to be subjected to AF) or may be a different area.

  In step S103, when the subject (subject area) determined in step S102 is the main subject to be subjected to AF, the system control unit 114 performs focus adjustment so that the lens unit 101 focuses on the main subject. The system control unit 114 can perform focus adjustment by driving the focus lens driving unit 108 using, for example, the distance measurement method determined in S101. The AF processing of the phase difference detection method and the contrast detection method based on the image signal obtained from the image sensor 109 and the AF processing of the phase difference detection method based on the distance measurement sensor 126 can be realized by a known method, and thus the detailed description is omitted. In S103, when the focusing operation on the subject is started, the process can immediately proceed to S104 while performing the focusing operation (while controlling the focus lens driving unit 108). That is, there is no need to wait for the completion of focusing on the subject before proceeding to S104. When the imaging apparatus 100 is set to the manual focus mode, the process of S103 is omitted. Note that, of the subjects whose distance is determined in S102, the subject that is not the main subject is not focused at this timing.

  In step S104, the system control unit 114 obtains the subject distance (distance between the subject and the image sensor 109) determined in step S102 using the distance measurement method determined in step S101, and stores the distance in the system memory 116. For example, a defocus amount is obtained from a focus detection area set corresponding to a subject whose distance is to be measured, and the distance is measured based on the current positions of the focus lens 106 and the variable power lens 103 and the obtained defocus amount. The distance of the subject determined as the subject is calculated. When a plurality of subjects are set as subjects to be measured for the distance, the current positions of the focus lens 106 and the variable power lens 103 and the defocus amounts acquired from the corresponding focus detection areas for each of the plurality of subjects. Is calculated based on the distance. As described above, the position of the focus lens 106 can be detected by the focus lens driving unit 108. Of the subjects determined as the subject for which the distance is to be measured in S102, the sub-subject (subject that is not the main subject) that is not the AF target is out of focus. Also for these sub-subjects, the subject distance is obtained based on the position of the focus lens 106, the position of the variable power lens 103, and the defocus amount for the sub-subject area.

  For example, for a plurality of discrete object distances as shown in FIG. 2, information indicating the relationship between the position of the variable power lens 103 and the position of the focus lens 106 during focusing is stored in the nonvolatile memory 117. Suppose you have In this case, the system control unit 114 determines the position of the focus lens 106 and the position of the variable power lens 103 when focusing on the subject of the distance measurement target, that is, when focusing on the subject area determined in S102. , The subject distance can be obtained.

Note that the subject for which the distance measurement determined in S102 is a specific feature area detected by the image processing unit 110 and this feature area moves within the angle of view (for example, if the subject specified as a tracking target is If you move). In this case, the subject region for which the distance is to be measured may be moved following the movement of the characteristic region, or may be fixed at a position once determined.
Also, here, a configuration has been described in which a subject area is determined, and then a distance at which the subject area is focused is obtained. However, for example, a subject image is determined after generating a range image indicating the subject distance for each pixel, and a distance corresponding to the subject region (for example, an average value of distances represented by pixels in the subject region) is obtained from the range image. Good.

  For example, the subject distance can be obtained for each pixel by obtaining the focus lens position at which the contrast evaluation value is maximized for each pixel. Also, distance information for each pixel is obtained based on the correlation between the amount of blur and the distance from image data obtained by shooting the same scene a plurality of times while changing the focusing distance and the point spread function (PSF) of the optical system. Can also be requested. These techniques are described in, for example, JP-A-2010-177741 and U.S. Pat. No. 4,965,840.

  When a parallax image pair can be acquired by the image sensor 109 as in the present embodiment, the subject distance can be acquired for each pixel by a method such as stereo matching. In this way, by previously obtaining the subject distance, in S102, the subject located at a specific distance (for example, the closest subject) can be determined as the subject of the distance measurement.

  In step S <b> 105, the system control unit 114 uses the subject distance calculated in step S <b> 104 and information indicating the relationship between the position of the variable power lens 103, the position of the focus lens 106, and the focusing distance stored in, for example, the nonvolatile memory 117. Then, the focus limit zoom magnification is obtained. For example, the system control unit 114 can obtain the focusing limit zoom magnification by searching for the position of the variable power lens 103 where the focus lens position for focusing on the subject distance calculated in S104 is the closest end. When two positions of the variable power lens 103 where the focus lens position is focused at the closest end for a certain subject distance are found, the subject distance has a maximum limit zoom magnification and a minimum limit zoom magnification. On the other hand, when one position of the variable power lens 103 at which the focus lens position is focused at the closest end for a certain subject distance is found, the subject distance has only the minimum limit zoom magnification.

  The system control unit 114 performs a display indicating the acquired focusing limit zoom magnification. The focus limit zoom magnification may always be displayed on the display unit 113, but particularly when the display unit 113 is small, the visibility of the live view image may be reduced. Therefore, in the present embodiment, the focus limit zoom magnification is displayed on the display unit 113 only when a specific condition is satisfied.

Specifically, in the present embodiment, the following changes in the shooting conditions shown in S106 and S107 are conditions.
-When the user performs a zoom operation (the zoom magnification changes)
・ When the subject distance changes (the focus limit zoom magnification changes)

  In S106, the system control unit 114 determines whether a zoom instruction has been input. If the zoom instruction has been input, the system control unit 114 proceeds to S108, otherwise proceeds to S107. Here, when the operation of the zoom lever 121 or another operation member to which the zoom function is assigned is detected or the zoom instruction is received through the external I / F 123, the system control unit 114 performs the zoom instruction. Can be determined to have been input.

  In S107, the system control unit 114 determines whether or not the subject distance calculated in S104 has changed by a threshold or more from the subject distance calculated when S104 was executed one time before. The threshold value used for this determination is a dynamic value according to the current subject distance, zoom magnification, and the like. Alternatively, if the subject distance calculated in S104 changes within a range of a distance having no defocus area (a range from infinity to 1 m in the example of FIG. 2), it may be determined that there is no change. If the subject distance has changed by the threshold or more, the system control unit 114 proceeds to S108, otherwise proceeds to S109.

  Thus, the focus limit zoom magnification can be displayed only when the relationship between the zoom magnification and the focus limit zoom magnification changes, such as when a zoom operation is performed or when the subject distance changes. Unnecessarily lowering the visibility of the view image can be suppressed. Note that only one of the zoom operation and the change in the subject distance may be used as the display condition of the focusing limit zoom magnification. The display condition may be selectable by the user.

  In S108, the system control unit 114 (display control unit) performs a display indicating the focusing limit zoom magnification acquired in S105. A display example at this time will be described later with reference to FIGS. Then, the system control unit 114 returns to S103 and repeatedly executes the above-described processing.

  In step S109, the system control unit 114 ends the display indicating the in-focus limit zoom magnification displayed in step S108 (not displayed). Then, the system control unit 114 returns to S103 and repeatedly executes the above-described processing.

  Note that the execution of S109 is skipped while the non-display state of the focusing limit zoom magnification continues. The calculation of the subject distance in S104 does not necessarily need to be executed for each frame.

FIG. 4 shows a focus limit zoom magnification (limit position) using a display item (zoom bar display unit) indicating the current zoom magnification (current zoom position) as an example of a display showing the focus limit zoom magnification in S108. The illustrated example is illustrated.
In FIG. 4A, a screen 200 is a display area of an external device communicable through the display unit 113 or the external I / F 123. A live view image 201 is displayed on the entire screen 200, and a zoom bar 202, a zoom bar display unit 203, a wide-angle end icon 204, a telephoto end icon 205, and a subject frame 206 are superimposed on the live view image 201.

  The horizontally long rectangular zoom bar display unit 203 indicates the entire movable range of the variable power lens 103, and the left end corresponds to the wide-angle end and the right end corresponds to the telephoto end. The zoom bar 202 is an area that expands to the right as the magnification increases, according to the magnification, and is painted black in the figure. The position of the right end of the zoom bar 202 indicates the current zoom magnification (the position of the zoom lens 103), but has a certain width even when the zoom magnification is minimum, in order to ensure visibility. Further, the wide-angle end icon 204 indicates that the left end of the zoom bar display unit 203 is the wide-angle end, and may be, for example, inverted when the current zoom magnification is the minimum (wide-angle end). Similarly, the telephoto end icon 205 indicates that the right end of the zoom bar display unit 203 is the telephoto end, and may be displayed in reverse video, for example, when the current zoom magnification is the maximum (telephoto end).

  FIG. 4A shows a display example of the focus limit zoom magnification when the zoom magnification is the minimum (wide-angle end). The subject frame 206 is an index indicating the subject whose distance has been calculated in S104. Here, it is assumed that the distance of the subject is 40 cm and the subject is in focus at the distance of the subject frame 206. A linear indicator 207 indicating the minimum limit zoom magnification is displayed on the zoom bar display unit 203. At this time, since the zoom bar 202 is displayed on the left side of the index 207 (current zoom magnification <minimum limit zoom magnification), it indicates that it is possible to zoom up to the position of the index 207 without blurring. Also, it indicates that the subject is blurred when zooming up beyond the index 207. When the subject distance is 40 cm, as shown in FIG. 2, there is no maximum limit zoom magnification, and thus the maximum limit zoom magnification is not displayed.

  FIG. 4B shows a display example in a state where the subject distance has changed to 70 cm and the subject is focused on the distance of the subject frame 206 in the state of FIG. At a subject distance of 70 cm, both the minimum limit zoom magnification and the maximum limit zoom magnification exist, so a linear indicator 208 indicating the maximum limit zoom magnification is additionally displayed on the zoom bar display unit 203. Further, a range of the zoom magnification corresponding to the defocus area between the minimum limit zoom magnification and the maximum limit zoom magnification is indicated by a U-shaped figure 211 and a numerical range 212 of the focal length of the lens unit. .

  At this time, similarly to FIG. 4A, the zoom bar 202 is displayed on the left side of the index 207, indicating that the user can zoom up to the position of the index 207 without blurring. The zoom magnification between the index 207 and the index 208 indicates that the subject is blurred. Further, it indicates that focusing can be performed again when zooming up beyond the index 208. Note that the minimum limit zoom magnification and the maximum limit zoom magnification may be displayed as numerical ranges of the zoom magnification based on the wide-angle end of the variable power lens 103.

  FIG. 4C shows a display example in a state where the subject distance remains 70 cm and the zoom magnification changes to a magnification between the minimum limit zoom magnification and the maximum limit zoom magnification in the state of FIG. 4B. ing. The fact that the current zoom magnification is in the defocus area and the subject in the subject frame 206 is blurred is displayed by displaying the range up to the maximum limit zoom magnification in a different color or pattern as shown by a shaded portion 221. Represents. At this time, as in FIG. 4B, it is shown that when the zoom-in is performed beyond the index 208, focusing can be performed again. In the drawing, the blurred subject in the live view image 201 is schematically represented by spots.

  FIG. 4D shows a display example in a case where there are a plurality of subjects determined in S102 in the same situation as in FIG. 4A. In this case, the zoom bar display unit 203 displays an index of the focusing limit zoom magnification for each subject. On the live view image 201, subject frames 231 and 232, which are indices indicating the determined subject, are superimposed and displayed. Thereby, the user can know the focus limit zoom magnification of each of the plurality of designated subjects.

  Further, on the live view image 201, focus assist figures 235 and 236 indicating the degree of focus of the subject corresponding to the subject frames 231 and 232, respectively, are superimposed and displayed. The focus assist graphic has a shape disclosed in, for example, Japanese Patent No. 6537325, in which the two triangles in FIG. 235 indicate the in-focus state, and the three triangles in FIG. 236 indicate the out-of-focus state of the front pin. This allows the user to simultaneously know the focus limit zoom magnification and the degree of focus for each of the plurality of designated subjects.

  The subject indicated by the subject frame 231 is a main subject (subject to be subjected to AF in the AF mode), and the subject indicated by the subject frame 232 is a sub subject (subject not subject to AF in the AF mode). The subject frames 231 and 232 have different colors and display patterns so that they can be visually distinguished. Here, the subject frame 231 is drawn by a solid line, and the subject frame 232 is drawn by a dotted line. The indices 233 and 234 of the focus limit zoom magnification in the zoom bar display unit 203 and the focus assist figures 235 and 236 are also displayed in different expressions for each corresponding subject.

  Here, the user can easily grasp the correspondence between the subject and the focusing limit zoom magnification by matching the expression of the index of the focusing limit zoom magnification (line type, color, etc.) with the subject frame for the same subject. ing. Therefore, the solid line index 233 indicates the focus limit zoom magnification (minimum limit zoom magnification) of the subject indicated by the subject frame 231. An index 234 indicated by a dotted line indicates a focus limit zoom magnification (minimum limit zoom magnification) of the subject indicated by the subject frame 232.

  Note that the display form of the subject frame and the focus limit zoom magnification index is common to all subjects, and other methods such as displaying the same number near the corresponding subject frame and the focus limit zoom magnification index are used. May represent the correspondence.

  In the example illustrated in FIG. 4, an index indicating the focus limit zoom magnification is determined by using the current zoom lens position (the focal length of the lens unit or the focal length of the lens unit or the focal length of the lens unit or the zoom range of the lens unit). It is displayed in the display item indicating (zoom magnification). Therefore, by displaying the focusing limit zoom magnification, the visibility of the live view image does not need to be reduced. In addition, since the user can simultaneously check the current zoom magnification and the focusing limit zoom magnification, the user can easily perform the zoom operation while considering the focusing limit zoom magnification. Although the example in which the focus limit zoom magnification (limit position) is indicated on the zoom bar display unit by an index (indicator) has been described, it may be displayed by a numerical value such as the zoom magnification or the focal length.

  As described above, in the present embodiment, the focus limit zoom magnification based on the distance (subject distance) from the distance measurement unit (the image sensor 109 or the distance measurement sensor 126) of the apparatus to the subject whose distance is to be measured is determined. Displayed. Therefore, the user can know the zoomable range while maintaining the in-focus state of the specific subject. The user performs the zoom operation while confirming the display of the focusing limit zoom magnification, so that the specific subject that has been in focus is blurred (out of focus) against the user's intention by the zoom operation. Can be prevented. In addition, since the change in the distance to the specific subject is reflected in the display of the focus limit zoom magnification, the zoom magnification can be appropriately adjusted even in shooting in which the distance to the specific subject changes.

  Further, it is possible to move (track) the area for calculating the focusing limit zoom magnification following the movement of the subject within the angle of view. Thus, even when the position of the subject changes within the angle of view due to the pan / tilt operation of the imaging device 100 or the movement of the subject, the desired subject can be tracked and the focusing limit zoom magnification can be calculated and displayed.

  In addition, by using the phase difference detection method in the image sensor 109 and the distance measuring sensor 126, the subject distance can be calculated even for an out-of-focus subject. Accordingly, even when the user performs focus adjustment in the manual focus (MF) mode, or when the subject distance changes rapidly in the AF mode and the focus lens 106 is moving to focus, the current focus position is maintained. Regardless of this, the focus limit zoom magnification can be displayed.

  Further, regardless of whether or not the user is in focus on the subject for which the focus limit zoom magnification is to be displayed, it is possible to display the focus limit zoom magnification for an arbitrary region within the angle of view and for a plurality of subjects.

  For example, consider a case where moving images of two subjects having different distances are photographed in the MF mode. At first, zoom-in is performed while focusing on a distant subject A, and then focus is manually moved to a close side to focus on a near subject B. In this case, it is necessary to perform the zoom-up performed while keeping the object A in focus within a zoom magnification range that does not cause blurring when the object B is focused later. That is, the user needs to know the focus limit zoom magnification for the subject B that is not focused during the zoom-up operation. By using the phase difference detection method in the image sensor 109 and the distance measuring sensor 126, it is possible to measure the subject distance and display the focusing limit zoom magnification even for an out-of-focus subject. Thereby, even when the subject A is focused on the subject B, the nearby subject B can be focused without blurring.

  Further, for example, it is assumed that while a moving image of a distant subject C is being shot at a high zoom magnification, another subject D that is suddenly close comes into the angle of view and it is desired to focus on the subject D. At this time, the subject frame 206 in FIG. 4C is the subject D, and is photographed out of focus. Here, when AF is enabled, the system control unit 114 attempts to focus on the subject D, but cannot perform focusing because the current zoom magnification is a defocus area at the distance of the subject D.

  At this time, the zoom bar display unit 203 displays that the current zoom magnification is between the minimum limit zoom magnification index 207 and the maximum limit zoom magnification index 208 and cannot be focused. That is, by checking the zoom bar display unit 203, the user can understand that the subject D cannot be focused at the current zoom magnification, and that the user needs to zoom out to focus on the subject D. At the same time, it is possible to know to which zoom magnification the focusing can be performed. In this way, by displaying the focusing limit zoom magnification, if another subject suddenly enters the field of view, it is likely that the subject is simply not in focus. The user can know whether or not the user can be impatient. Thus, it is possible to prevent the user from being unable to grasp the cause of the blur of the subject in the defocus area and to continue shooting.

<Second embodiment>
Next, a second embodiment of the present invention will be described. Since the present embodiment can be implemented by the imaging device 100 described in the first embodiment, description of the configuration of the imaging device will be omitted. According to the configuration of the first embodiment, the user can know the zoomable range while maintaining the in-focus state of the specific subject. However, it is conceivable that the zoom bar display unit 203 may be overlooked during zooming or the operation may be erroneously performed to zoom to the defocus area. Therefore, in the present embodiment, when the current zoom magnification approaches the focusing limit zoom magnification during zooming, zooming is automatically stopped.

  Next, a zoom control operation performed by the system control unit 114 in the present embodiment will be described with reference to the flowchart in FIG. The operation described below is realized by loading a program stored in the nonvolatile memory 117 into the system memory 116 and executing the program by the system control unit 114. Note that “zoom magnification” in the following description can be read as “position of the zoom lens 103” or “focal length of the lens unit 101”. In FIG. 5, steps for performing the same processing as in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  S101 to S102 are the same as in the first embodiment. However, the subject determined in S102 is not only a distance measurement target but also a target for performing the zoom operation control of the present embodiment.

  In step S <b> 203, the system control unit 114 determines a zoom method in a zoom magnification range (a defocus area) where the subject is not focused. Specifically, when it is necessary to zoom the image at the zoom magnification included in the defocus area, the system control unit 114 determines whether to use the optical zoom or the electronic zoom. Since the optical zoom does not focus on the subject, the target subject for distance measurement in the image is blurred (other subjects may be in focus). On the other hand, when electronic zooming is performed on an image obtained at a zoom magnification other than the defocus area, the resolution of the entire image decreases as the electronic zoom magnification increases, but the subject to be measured for distance is blurred due to optical factors. There is no.

  The system control unit 114 can determine a zoom method according to, for example, a user setting. The user setting may be performed in advance, or may be set by the user when executing S203. Note that, in order to improve the image quality of an image corresponding to the zoom magnification of the defocus area, the optical zoom and the electronic zoom may be used together. For example, by combining an image obtained by the electronic zoom and an image obtained by the optical zoom by giving priority to an area in focus in the optical zoom, an image corresponding to the zoom magnification of the defocus area is obtained. May be generated.

  In step S204, the system control unit 114 resets a flag (limit flag) indicating that the current zoom magnification has approached the focusing limit zoom magnification to zero. The limit flag is a variable stored in the system memory 116, for example, and indicates that 1 approaches the focusing limit zoom magnification.

Steps S103 to S105 are the same as those in the first embodiment, and a description thereof will not be repeated.
In step S207, the system control unit 114 determines whether an instruction to increase the zoom magnification (an enlargement zoom instruction or a zoom-in instruction) has been input. Then, the system control unit 114 proceeds to S208 if the enlargement zoom instruction has been input, and otherwise proceeds to S220. Here, if an operation to increase the zoom magnification is detected for the zoom lever 121 or another operation member to which the zoom function is assigned, the system control unit 114 determines that the enlargement zoom instruction has been input. be able to. Also, the system control unit 114 can determine that the enlargement zoom instruction has been input even when an instruction to increase the zoom magnification has been received through the external I / F 123.

  If the position of the zoom lens 103 is at the telephoto end, the optical zoom magnification cannot be increased. Therefore, in step S208, the system control unit 114 acquires the position of the variable power lens 103 through the variable power lens driving unit 107, and determines whether the position of the variable power lens 103 is at the telephoto end. If the position of the zoom lens 103 is at the telephoto end, the system control unit 114 proceeds to S220 without performing zoom-in driving, and otherwise proceeds to S209.

  In steps S209 and S210, the system control unit 114 calculates the zoom magnification (current zoom magnification) corresponding to the current position of the zoom lens 103 obtained via the zoom lens driving unit 107, and the minimum limit zoom magnification acquired in step S105. Compare.

  If the current zoom magnification is smaller than the minimum limit zoom magnification (on the wide angle side) and the current zoom magnification is near the minimum limit zoom magnification (Y in S209 and S210), the system control unit 114 proceeds to S211. Proceed, otherwise proceed to S219. Note that the vicinity in S210 indicates that the difference between the current zoom magnification and the minimum limit zoom magnification is less than the threshold. This threshold value can be dynamically determined based on the current subject distance, zoom magnification, and the like in consideration of the possibility that the subject distance changes after the zoom is stopped in S213 to be described later and focusing cannot be performed. Alternatively, the threshold may be a fixed value. The threshold may be set (changed) by the user. The case of Y in S209 and S210 is, in other words, the case where the zoom magnification is zoomed in to the threshold magnification indicating that the zoom magnification is closer to the minimum limit zoom magnification on the wide angle side than the minimum limit zoom magnification during zooming in.

  Instead of the determination processing in S209 and S210, the system control unit 114 determines whether the current zoom magnification is equal to the minimum limit zoom magnification (there is no difference between the current zoom magnification and the minimum limit zoom magnification). May be performed. In this case, the system control unit 114 proceeds to S211 when the current zoom magnification is equal to the minimum limit zoom magnification, and proceeds to S219 otherwise.

  The step S211 is executed when the zoom magnification approaches (or matches) the minimum limit zoom magnification in the process of the enlargement zoom. Therefore, in S211, the system control unit 114 determines whether or not the limit flag is 1. Then, the system control unit 114 proceeds to S212 when the limit flag is 1, and proceeds to S215 otherwise.

  In S212, the system control unit 114 sets the limit flag to 1. Note that this limit flag is reset to 0 when the zoom instruction is performed in the reverse direction. That is, when the limit flag is set to 1 during zooming in, the zoom flag is reset when zoomed out, and when the limit flag is set to 1 during zoom out, zooming is reset.

In step S <b> 213, the system control unit 114 stops the zoom lens 103 through the zoom lens driving unit 107. That is, even if the wide-angle zoom instruction is continued (even if the zoom-in operation is continued), the zoom driving is temporarily stopped. As a result, it is possible to prevent a specific subject from being blurred due to the zoom magnification entering the defocus area due to the zoom-in.
In step S214, the system control unit 114 starts the system timer 115, and starts measuring the elapsed time from the stop of the movement of the variable power lens 103.

  In S215, the system control unit 114 determines whether the measurement time of the system timer 115 started in S214 has reached a predetermined time. This predetermined time is used as a condition for restarting the zoom operation stopped when the current zoom magnification reaches or approaches the minimum limit zoom magnification in S217 or S218 described later. Therefore, it is sufficient if the length is long enough for the user to sufficiently recognize that the zoom operation has stopped. If the length is too long, there is a possibility of giving anxiety to the user. For example, the time can be set to about 0.5 to 1 second, but this time is merely an example. If the time measured by the system timer 115 has reached the predetermined time, the system control unit 114 proceeds to S216, otherwise returns to S103.

  In step S216, the system control unit 114 determines whether the zoom method determined in step S203 is the optical zoom. If the zoom method is the optical zoom, the system control unit 114 proceeds to S217; otherwise (the case of electronic zoom), the system control unit 114 proceeds to S218. In this flowchart, it is assumed that one of the optical zoom and the electronic zoom is determined in S203, but the optical zoom and the electronic zoom may be used in combination as described above. When the optical zoom and the electronic zoom are used together, the system control unit 114 proceeds to S217.

In steps S217 and S219, the system control unit 114 moves the variable power lens 103 to the telephoto side by a predetermined amount through the variable power lens driving unit 107, and returns to S103.
In step S218, the system control unit 114 cuts out the target area from the image data transferred to the memory 112, controls the image processing unit 110 to perform a predetermined amount of electronic zoom processing toward the telephoto side, and then returns to step S103.

  After the zoom is automatically stopped in S213, the zoom instruction is temporarily released (temporarily cancels the zoom operation), and if there is a zoom-in instruction (zoom-in operation) again, without waiting for the elapse of the predetermined time in S215. The process may proceed to S216 to zoom in. Thus, when the user wants to quickly zoom in without waiting for the elapse of the predetermined time, the user can recognize the boundary with the defocus area by performing automatic stop once and then quickly zoom in intentionally.

The processing of S220 to S230 is replaced by executing the same processing as that of S207 to S219 for zooming in the reduction direction.
In S220, the system control unit 114 determines whether an instruction to reduce the zoom magnification (a reduction zoom instruction, a zoom out instruction) has been input. Then, the system control unit 114 proceeds to S221 if the reduction zoom instruction has been input, otherwise proceeds to S231. Here, the system control unit 114 determines that a reduction zoom instruction has been input if an operation of lowering the zoom magnification is detected for the zoom lever 121 or another operation member to which the zoom function is assigned. be able to. Also, the system control unit 114 can determine that the reduction zoom instruction has been input even when receiving an instruction to lower the zoom magnification through the external I / F 123.

  If the position of the variable power lens 103 is at the wide angle end, the optical zoom magnification cannot be reduced. Therefore, in step S <b> 221, the system control unit 114 acquires the position of the variable power lens 103 through the variable power lens driving unit 107 and determines whether the position of the variable power lens 103 is at the wide angle end. If the position of the zoom lens 103 is at the wide-angle end, the system control unit 114 proceeds to S231, otherwise proceeds to S222.

  Before proceeding to S222, the system control unit 114 may determine whether or not the maximum limit zoom magnification has been acquired in S105. This is because there is a case where the maximum limit zoom magnification does not exist as described with reference to FIG. If the maximum limit zoom magnification has been acquired, the system control unit 114 proceeds to S222, otherwise proceeds to S230.

  In steps S222 and S223, the system control unit 114 sets the zoom magnification (current zoom magnification) corresponding to the current position of the variable power lens 103 obtained via the variable power lens driving unit 107, and the maximum limit zoom magnification acquired in step S105. Compare.

  If the current zoom magnification is larger than the maximum limit zoom magnification (on the telephoto side) and the current zoom magnification is near the maximum limit zoom magnification (Y in S222 and S223), the system control unit 114 proceeds to S224. Proceed, otherwise proceed to S230. Note that the vicinity in S223 indicates that the difference between the current zoom magnification and the maximum limit zoom magnification is equal to or smaller than the threshold. This threshold value may be the same as the value used in S210, or may be a different value. How to determine the threshold value is as described in S210. The case of Y in S222 and S223 is, in other words, the case where the zoom magnification is zoomed out to a threshold magnification indicating that the zoom magnification is closer to the maximum limit zoom magnification on the telephoto side than the maximum limit zoom magnification during zooming out. is there.

  Note that, instead of the determination processing of S222 and S223, the system control unit 114 may determine whether the current zoom magnification is equal to the maximum limit zoom magnification. In this case, the system control unit 114 proceeds to S224 if the current zoom magnification is equal to the maximum limit zoom magnification, otherwise proceeds to S230.

  S224 is executed in a state where the zoom magnification approaches (or matches) the maximum limit zoom magnification in the process of the reduction zoom. Therefore, in S224, the system control unit 114 determines whether or not the limit flag is 1. Then, the system control unit 114 proceeds to S225 if the limit flag is 1, and proceeds to S228 otherwise.

In S225, the system control unit 114 sets the limit flag to 1.
In step S <b> 226, the system control unit 114 stops the zoom lens 103 through the zoom lens driving unit 107. That is, even if the reduction zoom instruction is continued (even if the zoom-out operation is continued), the zoom driving is temporarily stopped. As a result, it is possible to prevent a specific subject from being blurred due to the zoom magnification entering the defocus area due to zooming out.
In step S227, the system control unit 114 activates the system timer 115 and starts measuring the elapsed time from the stop of the movement of the variable power lens 103.

  In S228, the system control unit 114 determines whether or not the measurement time of the system timer 115 started in S227 has reached a predetermined time. This predetermined time is used as a condition for resuming the zoom operation stopped when the current zoom magnification reaches or approaches the maximum limit zoom magnification in S229 described later. Therefore, it is sufficient if the length is long enough for the user to sufficiently recognize that the zoom operation has stopped. Here, the predetermined time is the same as S215, but may be different. If the measurement time of the system timer 115 has reached the predetermined time, the system control unit 114 proceeds to S229, otherwise returns to S103.

  After the zoom is automatically stopped in S226, the zoom instruction (operation) is temporarily released, and if there is a zoom-out instruction (operation) again, the process proceeds to S226 without waiting for the elapse of the predetermined time in S228, and the data is deleted. Zoom-out that enters the focus area may be performed. Thus, when the user wants to quickly zoom out without waiting for the elapse of a predetermined time, the user can recognize the boundary with the defocus area by automatically stopping once, and can quickly zoom out intentionally.

  Note that the process corresponding to S216 is not performed during zooming in the reduction direction. This is because it is impossible to reduce the zoom by the electronic zoom unless a process corresponding to the electronic zoom has been performed in advance.

  In S229 and S230, the system control unit 114 moves the variable power lens 103 to the wide angle side by a predetermined amount through the variable power lens driving unit 107, and returns to S103. In step S230, if the zoom lens 103 is stopped, the system control unit 114 resets the system timer 115 and the limit flag, and then moves the zoom lens 103.

In S231, the system control unit 114 resets the limit flag to 0.
In step S <b> 232, the system control unit 114 stops the zoom lens 103 through the zoom lens driving unit 107.
In S233, the system control unit 114 cancels the timer whose measurement has been started in S214 or S227.

  Here, as a specific example, consider a case where the enlargement zoom operation is continuously performed from the wide-angle end. The system control unit 114 continuously moves the zoom lens 103 to the telephoto side according to the enlargement zoom operation. Then, when the current zoom magnification is close to the minimum limit zoom magnification, the zoom lens 103 is automatically stopped. When a predetermined time has elapsed while the enlargement zoom operation is continued, the system control unit 114 resumes moving the variable power lens 103 to the telephoto side.

  In this case, in the flowchart of FIG. 5, the system control unit 114 first performs the processing from S201 to S105, and then proceeds from S207 to S208. Since the current zoom magnification is at the wide-angle end, the system control unit 114 proceeds from S208 to S209. Further, although the current zoom magnification is smaller than the minimum zoom magnification, it is not a value near the minimum zoom magnification. Therefore, the system control unit 114 moves the variable power lens 103 to the telephoto side by a predetermined amount in S219, and returns to S103. Until the current zoom magnification becomes a value near the minimum limit zoom magnification, the system control unit 114 repeats the processing of S103 to S210 to S219. As a result, the subject image is enlarged.

  When the current zoom magnification becomes a value near the minimum limit zoom magnification, the system control unit 114 proceeds from S210 to S211. Since the flag has not been set since it was reset to 0 in S204, the system control unit 114 performs the processing of S212 to S214. At this time, the variable power lens 103 stops in S213.

  Until the measurement time of the system timer 115 set in S214 reaches a predetermined time, the system control unit 114 repeatedly executes the loop of S104 to S215. At this time, in the second and subsequent processes, the processes of S212 to S214 are skipped. Further, the variable power lens 103 maintains the stopped state.

  When the measurement time of the system timer 115 reaches a predetermined time, the system control unit 114 proceeds from S215 to S216. For example, assuming that the optical zoom is performed in the defocus area, the system control unit 114 restarts moving the variable power lens 103 to the telephoto side in S217, and repeatedly executes the loop of S104 to S217. At this time, the processing of S212 to S214 is not performed.

Thereafter, when the current zoom magnification reaches the minimum limit zoom magnification, the system control unit 114 proceeds from S209 to S219. Thereafter, the system control unit 114 repeatedly executes a loop of S104 to S209 to S219 until the zoom magnification reaches the telephoto end.
When the zoom magnification reaches the telephoto end, the system control unit 114 proceeds from S208 to S220, further proceeds to S231, executes the processing of S231 to S233, and stops the variable power lens 103.

  The zoom control operation shown in FIG. 5 can be executed in combination with the limit zoom magnification display process described in the first embodiment.

  As described above, in the present embodiment, when the current zoom magnification approaches the limit zoom magnification for a specific subject, the zoom operation is automatically stopped. Therefore, if the user continues the zoom operation and stops the zoom operation at the time of noticing that the zoom has automatically stopped, the subject can be reliably prevented from being blurred.

  Furthermore, when the zoom operation is continued for a predetermined time or more while the zoom is automatically stopped, the zoom operation is restarted. This enables photographing that reflects the user's intention. Further, as a method for obtaining an image corresponding to a zoom magnification at which the subject cannot be focused by the optical zoom, the optical zoom and the electronic zoom can be selected, so that an image according to the user's desire can be obtained.

  Further, when the limit zoom magnification changes, for example, when the subject distance changes by a predetermined amount or more, the zoom operation is also performed based on the changed limit zoom magnification, so that it is possible to accurately avoid subject blur. it can. For example, when the subject distance is shortened due to a change in the subject in the subject area during the enlargement zoom, the zoom operation control is performed based on the focusing limit zoom magnification for the shortened subject distance.

  Further, in the present embodiment, when the current zoom magnification is a value near the focus limit zoom magnification (the zoom magnification at which the determination in S210 is true), and a new zoom instruction is issued without a zoom instruction. Also, when a zoom instruction is detected continuously for a predetermined time, the zoom operation is started. Thereby, even when performing zooming from a zoom magnification close to the focusing limit zoom magnification, the user can know that focusing cannot be performed by optical zooming. If the zoom operation is not performed immediately in response to the zoom operation, the user stops the zoom operation at that point, and the zoom operation is not performed. Therefore, it is possible to prevent an unintentionally blurred image from being shot.

  In the present embodiment, it is also possible to specify a plurality of distance measuring methods and a plurality of subjects. In this case, the zoom lens 103 may be stopped only when the current zoom magnification reaches the vicinity of the lowest value among the plurality of minimum limit zoom magnifications, or may change every time the current zoom magnification reaches the vicinity of the minimum limit zoom magnification. The double lens 103 may be stopped. When the variable power lens 103 is stopped at the individual minimum limit zoom magnifications, if two subjects at different distances are targeted, the minimum limit zoom magnification for the nearer subject and the minimum limit zoom magnification for the farther subject In each case, the variable power lens 103 stops. Thereby, the user can know the focus limit zoom magnification of each of the plurality of designated subjects.

  Note that the processing shown in FIG. 5 can be performed during standby for capturing a still image, during standby for recording a moving image, or during recording of a moving image. If the processing shown in FIG. 5 is performed during the recording of a moving image, it is possible to prevent a video in which a specific subject is blurred due to zoom-in or zoom-out from being recorded.

  Further, the processing shown in FIG. 5 may be performed only when a specific condition is satisfied. For example, when the shooting mode of the image capturing apparatus 100 is a mode in which images are continuously recorded, such as a moving image mode, the processing in FIG. 5 may be performed only during recording standby. In this case, since the zoom operation does not stop automatically during recording, it is possible to take a picture that respects the user's intention. On the other hand, by temporarily stopping the zoom operation in the vicinity of the focus limit zoom magnification during recording standby, the user can easily know the focus limit zoom magnification and easily determine the shooting angle of view. This makes it possible for the user to know the focus limit zoom magnification and to avoid recording an image in which the zoom is automatically stopped.

<Other embodiments>
Note that the above-described various controls described as being performed by the system control unit 114 may be performed by a single piece of hardware, or a plurality of pieces of hardware (for example, a plurality of processors or circuits) may share the processing, and Overall control may be performed.

  Although the present invention has been described in detail based on the preferred embodiments, the present invention is not limited to these specific embodiments, and various forms that do not depart from the gist of the present invention are also included in the present invention. included. Furthermore, each of the above-described embodiments is merely an embodiment of the present invention, and the embodiments can be appropriately combined.

  The present invention is not limited to the imaging device main body, and can be applied to a control device that communicates with an imaging device (including a network camera) via wired or wireless communication and controls the imaging device remotely. Examples of a device that remotely controls the imaging device include devices such as a smartphone, a tablet PC, and a desktop PC. It is possible to remotely control the imaging device by notifying the imaging device of commands for performing various operations and settings from the control device based on operations performed on the control device and processes performed on the control device. is there. Alternatively, the live view image captured by the imaging device may be received via a wired or wireless communication and displayed on the control device side.

  The present invention supplies a program for realizing one or more functions of the above-described embodiments to a system or an apparatus via a network or a storage medium, and one or more processors in a computer of the system or the apparatus read and execute the program. This processing can be realized. Further, it can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

REFERENCE SIGNS LIST 100 imaging device 101 lens unit 103 zoom lens 106 focus lens 107 zoom lens driving unit 108 focus lens driving unit 109 imaging device 114 system control unit

Claims (18)

Acquiring means for acquiring a defocus amount for a focus detection area corresponding to a specific subject;
Control means for controlling to perform optical zoom according to the zoom instruction;
A display indicating a limit position that is a limit optical zoom position at which the specific subject can be focused even when the specific subject is not focused based on the defocus amount acquired by the acquisition unit. Display control means for controlling the display on the display means,
A zoom control device, comprising:   The said acquisition means can acquire the defocus amount about the some focus detection area | region corresponding to each several object, and the said specific object is one of the several objects, The characterized by the above-mentioned. Item 2. The zoom control device according to item 1.   The zoom control device according to claim 2, wherein the specific subject is a different subject from the focused subject among the plurality of subjects.   4. The zoom control device according to claim 2, wherein the specific subject is a subject different from a main subject to be subjected to autofocus among the plurality of subjects. 5.   The display control unit is a plurality of optical zoom positions corresponding to each of the plurality of subjects, each of which is capable of being focused, based on the defocus amounts of the plurality of focus detection areas acquired by the acquisition unit. The zoom control device according to any one of claims 2 to 4, wherein control is performed so as to display a limit position of the zoom lens.   The display control unit displays the limit position when the optical zoom is performed, and before the optical zoom is performed, the zoom is stopped, and the display control unit changes the defocus amount acquired by the acquisition unit. The zoom control device according to any one of claims 1 to 5, wherein control is performed such that the limit position is not displayed in a state where there is no image.   7. The zoom control device according to claim 6, wherein the display control unit controls to display the limit position when the defocus amount acquired by the acquisition unit changes by a predetermined amount or more.   The zoom control device according to any one of claims 1 to 7, wherein the display control means displays on the display means a current zoom position in addition to the limit position.   9. The zoom control device according to claim 8, wherein the display control means displays the limit position using a display item indicating a current zoom position from a wide-angle end to a telephoto end.   The control means controls the current zoom position during the driving of the optical zoom from the zoom position at which the in-focus subject can be kept in focus, and a limit at which the in-focus subject can be kept in focus. The optical zoom position according to any one of claims 1 to 9, wherein the zoom is automatically stopped when the difference from the limit position of the focused object disappears or becomes equal to or less than a threshold value. The zoom control device according to any one of the preceding claims.   After the zoom is automatically stopped by the control means, if a zoom instruction to be continued for a predetermined time is continuously performed before the zoom is automatically stopped, the control means restarts the zoom in a predetermined method. The zoom control device according to claim 10, wherein the zoom control is performed.   After the zooming is automatically stopped by the control means, the zoom instruction to be continued from before the zoom is automatically stopped is temporarily released, and when the zoom instruction in the same direction is performed again, the control means sets a predetermined value. The zoom control device according to claim 10, wherein the zoom is performed by a given method.   13. The zoom control device according to claim 11, wherein the predetermined method is a method of performing optical zoom beyond a limit position of the focused object.   13. The zoom control device according to claim 11, wherein the predetermined method is a method of performing zooming while maintaining a focused state on the focused object using an electronic zoom. .   15. The zoom control device according to claim 1, further comprising an imaging unit configured to image a subject. A control method of a zoom control device,
An acquisition step of acquiring a defocus amount for a focus detection area corresponding to a specific subject;
Controlling the optical zoom in response to a zoom instruction, and focusing on the specific subject based on the defocus amount acquired in the acquiring step even when the specific subject is not focused. A display control step of controlling a display indicating a limit position that is an optical zoom position of a limit capable of being displayed on the display means,
A control method for a zoom control device, comprising:   A program for causing a computer to function as each unit of the zoom control device according to claim 1.   A computer-readable storage medium storing a program for causing a computer to function as each unit of the zoom control device according to claim 1.

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