Imaging apparatus

Abstract

To stabilize focusing in manual focus photographing.SOLUTION: A first imaging device includes an imaging element that captures an image formed by an imaging optical system having a focus lens, and a control unit that moves the focus lens such that the image formed by the imaging optical system is focused on the imaging element in a case where a deviation between the image formed by the imaging optical system and the imaging element is included in a predetermined range after a manual focus operation is performed. A second imaging device includes an imaging element that captures an image formed by an imaging optical system having a focus lens, a calculation unit that calculates a defocus amount indicating a deviation between the image formed by the imaging optical system and the imaging element, and a control unit that performs auto-focus control for moving the focus lens based on the calculated defocus amount in a case where the calculated defocus amount is included in a predetermined range after a manual focus operation is performed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an imaging device. [Background technology]

[0002] BACKGROUND ART In imaging devices such as cameras, imaging devices that improve the focusing accuracy during manual focus (MF) photography have been proposed (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2015-031946 Summary of the Invention

[0004] An imaging device according to a first aspect includes an imaging element that captures an image formed by an imaging optical system having a focus lens, and a control unit that moves the focus lens so that the image formed by the imaging optical system is focused on the imaging element when the deviation between the image formed by the imaging optical system and the imaging element is within a predetermined range after a manual focus operation is performed.

[0005] An imaging device according to a second aspect includes an imaging element that captures an image formed by an imaging optical system having a focus lens, a calculation unit that calculates a defocus amount that represents the deviation between the image formed by the imaging optical system and the imaging element, and a control unit that performs autofocus control to move the focus lens based on the calculated defocus amount when the calculated defocus amount is within a predetermined range after a manual focus operation is performed. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an imaging device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an outline of the assist control. [Figure 3] FIG. 3 is a simple flowchart showing an example of the operation of the assist control. [Figure 4] FIG. 4 is a detailed flowchart showing an example of the operation of the assist control. [Figure 5] FIG. 5 is a flowchart showing an example of the subject setting process. [Figure 6] FIG. 6 is a flowchart showing an example of the subject selection process. [Figure 7] Figure 7(a) is a diagram showing a first example of the display content displayed on the display unit of an imaging device according to one embodiment, Figure 7(b) is a diagram showing a second example of the display content, and Figure 7(c) is a diagram showing a third example of the display content. DETAILED DESCRIPTION OF THE INVENTION

[0007] When a photographer captures a specific subject through video recording, there is a need to capture the entire process from an out-of-focus state to a fully focused state as part of the recording. One possible way to capture this process is to record video using manual focus. However, before achieving a fully focused state through manual focus operation, trial and error may occur, such as turning the focus ring back after going too far. Recording such trial and error is not desirable in video recording. Furthermore, in recent years, systems for recording video have become increasingly large, with the addition of large displays that allow the photographer to visually confirm the focus point, which is displayed on the display as the target position for focus control and superimposed on the image. This can result in a heavier and / or larger camera, making the camera unwieldy and making it difficult to achieve focus through manual focus operation.

[0008] In the electronic camera according to this embodiment (an example of an imaging device, hereinafter referred to as camera 1), after a manual focus operation is performed, if the deviation between the image formed by the imaging optical system 31 and the imaging element 22 is within a predetermined range, the focus lens 31a is moved so that the image formed by the imaging optical system 31 is focused on the imaging element 22.

[0009] Hereinafter, the determination of whether the deviation between the image formed by the imaging optical system 31 and the imaging element 22 falls within a predetermined range after a manual focus operation is performed will also be referred to as "defocus amount determination." Furthermore, the control of moving the focus lens 31a so that the image formed by the imaging optical system 31 is focused on the imaging element 22 will also be referred to as "lens drive control." Furthermore, the defocus amount determination and lens drive control will be collectively referred to as "assist control."

[0010] The manual focus operation is an example of a manual operation, and is a focus operation manually performed by the photographer using camera 1. The manual focus operation can also be said to be an operation performed by the photographer using camera 1 to move focus lens 31a.

[0011] FIG. 1 is a diagram showing an example configuration of a camera 1 according to one embodiment. Camera 1 is made up of a camera body 2 and a lens unit 3. Camera 1 made up of camera body 2 and lens unit 3 may also be called a camera system. Camera 1 may be configured as an interchangeable lens camera in which lens unit 3 is detachable from camera body 2, or may be configured as an integrated camera in which camera body 2 and lens unit 3 are not detachable. In the following description, camera 1 will be described as an interchangeable lens camera in which lens unit 3 is detachable from camera body 2.

[0012] The camera body 2 is provided with a body-side mount section 201 to which the lens unit 3 is attached. The lens unit 3 is provided with a lens-side mount section 301 to which it is attached to the camera body 2. The body-side mount section 201 and the lens-side mount section 301 are provided with a body-side connection section 202 and a lens-side connection section 302, respectively. The lens unit 3 is attached to the camera body 2 via the body-side mount section 201 and the lens-side mount section 301. When the lens unit 3 is attached to the camera body 2, a terminal provided on the body-side connection section 202 and a terminal provided on the lens-side connection section 302 are electrically connected. This enables power to be supplied from the camera body 2 to the lens unit 3 and communication between the camera body 2 and the lens unit 3.

[0013] The lens unit 3 includes an imaging optical system 31, a lens control unit 32, a lens storage unit 33, a focus ring 34, an encoder 35, and a drive motor 36. The imaging optical system 31 includes a plurality of lenses including a focus lens group 31a having at least one lens component (a single lens or a cemented lens), and an aperture, and forms an image of a subject on the imaging plane of the image sensor 22. The imaging optical system 31 may be a variable magnification optical system or an optical system with a fixed focal length. The imaging optical system 31 may also include two or more focus lens groups 31a. The focus lens group 31a may be composed of two or more lens components.

[0014] The focus lens group 31a moves along the optical axis O, thereby adjusting the focal length of the imaging optical system 31. The position of the focus lens group 31a is detected by an encoder 35, and the position is adjusted by a drive motor 36. For ease of explanation, the focus lens group 31a will be described below simply as the focus lens 31a.

[0015] The specific configuration of the mechanism for moving focus lens 31a along optical axis O is not particularly limited. One example is a configuration in which a rotating cylinder is rotatably inserted into a fixed cylinder fixed to lens unit 3, a helicoid groove is formed on the inner peripheral surface of this rotating cylinder, the end of a lens frame that fixes focus lens 31a is fitted into the helicoid groove, and the rotating cylinder is rotated by drive motor 36.

[0016] Position information of the focus lens 31a detected by the encoder 35 is output to the body control unit 21, which will be described later, via the lens control unit 32. Based on the position information of the focus lens 31a, the body control unit 21 generates a drive signal for moving the focus lens 31a to the in-focus position and outputs it to the lens control unit 32. Based on the drive signal output from the body control unit 21, the drive motor 36 drives a movement mechanism so that the focus lens 31a moves to the in-focus position. In the following, the position of the focus lens 31a will be described as being based on detection by the encoder 35, but the position of the focus lens 31a may also be detected by the drive steps of a stepping motor in the drive motor 36, or the like.

[0017] The focus lens 31a can also be moved by a movement operation by the photographer via a focus ring 34. The focus ring 34 is also called a focus ring, and receives a movement operation to move the focus lens 31a along the optical axis O.

[0018] The lens control unit 32 is configured with processors such as a CPU and FPGA, and memories such as a ROM and RAM, and controls each part of the lens unit 3 based on a control program stored in the lens storage unit 33. The lens control unit 32 controls the position of the focus lens 31a, the aperture diameter of the iris, etc., based on a signal output from the body control unit 21 of the camera body 2.

[0019] The lens storage unit 33 has a storage medium such as a nonvolatile semiconductor memory. The lens storage unit 33 stores information related to the lens unit 3 as lens information. The lens information includes, for example, data on optical characteristics such as the exit pupil distance and F-number of the imaging optical system 31, data on the infinity position and the closest position of the focus lens 31a, and data on the shortest focal length and the longest focal length of the lens unit 3.

[0020] The camera body 2 includes a body control unit 21, an image sensor 22, a body storage unit 23, a display unit 24, an operation unit 25, and an electronic viewfinder 26.

[0021] The imaging element 22 is a CMOS image sensor or a CCD image sensor. The imaging element 22 captures an image of a subject formed by the imaging optical system 31. The imaging element 22 is installed inside the opening of the body side mount unit 201 so that the imaging surface of the imaging element 22 faces the lens unit 3 attached to the camera body 2. In the imaging element 22, multiple pixels each having a photoelectric conversion unit are arranged two-dimensionally (in the row and column directions). The photoelectric conversion unit is composed of a photodiode (PD). The imaging element 22 photoelectrically converts received light in the photoelectric conversion unit to generate an image signal, and outputs the generated image signal to the body control unit 21.

[0022] The multiple pixels of the image sensor 22 include pixels for imaging and multiple pixels for phase-difference focus detection. The focus detection signals output from the pixels for phase-difference focus detection include first and second focus detection signals corresponding to first and second optical images formed by first and second light beams that have passed through first and second regions, respectively, of the exit pupil of the imaging optical system 31. The focus detection signals are sent to the body control unit 21 together with image signals output from the pixels for imaging. The pixels for phase-difference focus detection may also output image signals.

[0023] Based on the focus detection signal output from each phase-difference focus detection pixel, the body control unit 21 can calculate the amount of positional deviation (defocus amount) between the image formed by the imaging optical system 31 and the imaging surface of the imaging element 22 in the focus detection area (focus point), which is the area on the image corresponding to the phase-difference focus detection pixel.

[0024] The body storage unit 23 is composed of a non-volatile storage medium or the like, and image data, audio data, and the like are written to and read from the body control unit 21. The display unit 24 is, for example, an LED display, and displays an image corresponding to image data generated by the body control unit 21. The display unit 24 also displays various information related to shooting conditions (shutter speed, aperture value, ISO sensitivity, etc.) and menu screens, etc. The operation unit 25 includes a release button, a recording button, various setting switches, etc., and outputs signals to the body control unit 21 in response to operations of the operation unit 25. The operation unit 25 may be a touch panel superimposed on the display unit 24. The electronic viewfinder 26 displays an image corresponding to image data generated by the body control unit 21. The electronic viewfinder 26 also displays various information related to shooting conditions. The electronic viewfinder 26 has, for example, a display and an eyepiece, and the image and various information displayed on the display are observed by the photographer through the eyepiece.

[0025] The body control unit 21 is configured with processors such as a CPU and FPGA, and memories such as a ROM and RAM, and controls each unit of the camera 1 based on a control program stored in the body storage unit 23. The body control unit 21 also performs various types of signal processing. As an example, the body control unit 21 supplies control signals to the image sensor 22 to control the operation of the image sensor 22. The body control unit 21 also performs various types of image processing on the image signal output from the image sensor 22 to generate image data.

[0026] The body control unit 21 includes, as functional blocks, a subject detection unit 41, a setting unit 42, a defocus amount calculation unit 43, a determination unit 44, a drive control unit 45, and a display control unit 46. In the present embodiment, each of these units is a functional module realized based on a program executed by the body control unit 21, but each of these units may also be implemented in the camera 1 (camera body 2) as firmware.

[0027] The subject detection unit 41 detects a predetermined type of subject from image data generated by the body control unit 21. Examples of predetermined types of subjects include human faces, animals (e.g., dogs, cats, and birds), and vehicles (e.g., cars, motorcycles, trains, airplanes, and bicycles). The subject detection unit 41 detects a predetermined type of subject represented in the image data by inputting the image data to a classifier that has been trained in advance to detect predetermined types of subjects. The classifier outputs information indicating the area in which the detected subject is represented (e.g., the coordinates of the upper left corner and the lower right corner of the area) and information indicating the type of the detected subject. If the image data contains multiple subjects to be detected, the classifier outputs, for each subject, information indicating the area in which the subject is represented and information indicating the type of the detected subject. The classifier can be, for example, a so-called deep neural network (DNN) such as YOLO. Alternatively, the classifier may be based on a machine learning method other than DNN. Alternatively, the subject detection unit 41 may extract features such as SIFT or SURF from the image data and detect a predetermined type of subject based on the extracted features.

[0028] The setting unit 42 sets one of the subjects detected from the image data by the subject detection unit 41 as a specific subject for which the defocus amount is to be determined.

[0029] If the subject detection unit 41 does not detect a plurality of subjects from the image data, the setting unit 42 sets the detected subject as the specific subject.

[0030] When multiple subjects are detected from the image data, the setting unit 42 sets one selected from the multiple subjects as the specific subject. In one example, the setting unit 42 sets the subject that is closest to the imaging optical system 31 when a predetermined termination condition is met from among the multiple subjects as the specific subject (hereinafter, this setting will also be referred to as the "closest setting"). In one example, the subject closest to the imaging optical system 31 is detected by the body control unit 21 acquiring distance information for each subject based on a focus detection signal. Note that the body control unit 21 may detect the subject that occupies the largest proportion of the screen of the display unit 24 as the subject closest to the imaging optical system 31.

[0031] If the subject detection unit 41 does not detect a predetermined subject, or if the second setting mode is set, the setting unit 42 sets the subject represented in a focus detection area pre-selected from a plurality of focus detection areas as the specific subject. In other words, if the subject detection unit 41 does not detect a predetermined subject, or if the second setting mode is set, the defocus amount determination is performed based on the focus detection signal output from the phase difference focus detection pixel corresponding to the pre-selected focus detection area. Note that the second setting mode is a mode in which the subject represented in the pre-selected focus detection area is the subject of defocus amount determination, regardless of the result of subject detection.

[0032] The defocus amount calculation unit 43 is an example of a calculation unit, and calculates the defocus amount of the image of the subject represented in the image. The defocus amount can be said to be a value representing the position of the image formed by the imaging optical system 31 in the optical axis direction based on the imaging surface of the imaging element 22. The defocus amount can also be said to be a value representing the degree of focus deviation.

[0033] The determination unit 44 first determines whether the manual focus operation has satisfied a predetermined end condition, for example, that a first predetermined time has elapsed since the movement of the focus lens 31a due to the manual focus operation stopped.

[0034] The first predetermined time may be set or changed based on the speed of the focus lens 31a when a manual focus operation is performed. For example, the first predetermined time when the focus lens 31a moves at a first speed (low speed) when a manual focus operation is performed may be set or changed to be longer than the first predetermined time when the focus lens 31a moves at a second speed (high speed) that is faster than the first speed. This control prevents erroneous determination that the manual focus operation has ended even when the manual focus operation is still in progress. The speed of the focus lens 31a used in this control may be, for example, the average speed over a predetermined period immediately before the movement of the focus lens 31a due to the manual focus operation stops, or the speed at a certain point within that predetermined period. The speed of the focus lens 31a may also be calculated based on the speed at which the focus ring 34 is moved by the photographer.

[0035] The predetermined end condition may be that the movement direction of the focus lens 31a has reversed. The movement direction and stoppage of the focus lens 31a are detected by the encoder 35. The determination unit 44 may also determine whether the manual focus operation has satisfied the predetermined end condition based on the operation of the focus ring 34 and the position of the image in the focus detection area.

[0036] When it is determined that the manual focus operation has satisfied a predetermined end condition (i.e., after the manual focus operation has been performed), the determination unit 44 determines whether the defocus amount of the image of the specific subject is within a predetermined range (defocus amount determination). For example, the predetermined ranges are stored in the body storage unit 23, each corresponding to "narrow," "standard," and "wide," and the determination unit 44 reads out the predetermined range corresponding to the setting when determining the defocus amount. An example of a manual focus operation is a movement operation that moves the focus lens 31a along the optical axis O.

[0037] When the defocus amount after a manual focus operation is within a predetermined range, the drive control unit 45 generates a drive signal and outputs it to the lens control unit 32, causing the lens control unit 32 to operate the drive motor 36 and move the focus lens 31a so that the image formed by the imaging optical system 31 is focused on the image sensor 22. The drive control unit 45 determines the direction and amount of movement of the focus lens 31a toward the in-focus position depending on whether the subject image is in front focus or back focus, and generates a drive signal to move the focus lens 31a in that direction and by that amount. Whether the subject image is in front focus or back focus is determined by the determination unit 44. The display control unit 46 causes the display unit 24 to display content according to the defocus amount.

[0038] FIG. 2 is a diagram showing an overview of assist control according to this embodiment. In FIG. 2, the horizontal axis indicates the position of the image of the subject formed by the imaging optical system 31. In assist control, it is determined whether or not the defocus amount after a manual focus operation is within a predetermined range (defocus amount determination), and depending on the result, it is determined whether or not to execute control to move the focus lens 31a (lens drive control) so that the image formed by the imaging optical system 31 is focused on the image sensor 22. The defocus amount determination can also be said to be a determination of whether or not the image of the subject is formed within a predetermined range. The predetermined range can also be called an assist range, as it determines whether or not to execute lens drive control.

[0039] If the defocus amount is within a predetermined range after a manual focus operation, the drive control unit 45 moves the focus lens 31a so that the image formed by the imaging optical system 31 is focused on the image sensor 22. That is, the drive control unit 45 executes lens drive control. The lens drive control is a control for automatically adjusting the focus, so it can also be called autofocus control. If the defocus amount is not within the predetermined range after a manual focus operation, the drive control unit 45 does not execute lens drive control.

[0040] According to the assist control of this embodiment, after a manual focus operation is performed, it is determined whether or not to perform lens drive control based on the defocus amount, and if the defocus amount is within a predetermined range, lens drive control is performed. Therefore, when a photographer takes a photograph using manual focus, the assist control assists the photographer in achieving a focused state after the photographer's manual focus operation, enabling stable focusing. The assist control is particularly effective when shooting video, as it can reduce situations where the desired subject is not focused after a manual focus operation.

[0041] FIG. 3 is a simple flowchart showing an example of the operation of the assist control.

[0042] In step S101, the determination unit 44 determines whether or not the manual focus operation has ended (determination of the end of the manual focus operation).

[0043] In step S102, the determination unit 44 determines whether or not the defocus amount when a predetermined termination condition is satisfied is within a predetermined range (defocus amount determination).

[0044] In step S103, if the determination unit 44 determines that the deviation between the image formed by the imaging optical system 31 and the image sensor 22 is within a predetermined range, the drive control unit 45 executes lens drive control. In one example, the drive control unit 45 controls the drive motor 36 to move the focus lens 31a along the optical axis O so that the defocus amount is included in the depth of focus of the camera 1. In other words, the drive control unit 45 controls the position of the focus lens 31a so that the position of the image formed by the imaging optical system 31 is within the depth of focus of the camera 1.

[0045] Fig. 4 is a detailed flowchart showing an example of the operation of assist control. Figs. 5 and 6 are flowcharts showing detailed examples of the operation of predetermined steps in the flowchart shown in Fig. 4. The example of the operation of assist control will be described in detail with reference to Figs. 4 to 6. Note that step S201 in Fig. 4 corresponds to step S101 in Fig. 3 (determination of end of manual focus operation), steps S202 to S205 in Fig. 4 correspond to step S102 in Fig. 3 (determination of defocus amount), and steps S206 to S208 in Fig. 4 correspond to step S103 in Fig. 3 (lens drive control).

[0046] In the detailed description of the operation example of the assist control, a predetermined range that is an assist range that determines whether or not to execute lens drive control will be referred to as the first range. The first range is one of three different ranges (ranges corresponding to "narrow," "standard," and "wide") pre-stored in the body storage unit 23. The photographer can select one of the ranges as the first range based on a selection via the operation unit 25. Note that the setting of the first range is not limited to a selection from three ranges. Also, a range corresponding to a setting operation performed by the photographer on the operation unit 25 may be set as the first range.

[0047] In addition, in the detailed operation example of the assist control, the range stored in the body storage unit 23 for determining whether or not to terminate the lens drive control will be described as the second range. The second range is narrower than the first range, and in this embodiment is the focal depth of the camera 1.

[0048] In this embodiment, the operation unit 25 can accept switching between a first mode for assisting manual focus operation and a second mode that does not assist manual focus operation. The body control unit 21 executes assist control when the first mode is set. The operation unit 25 can also accept switching between a still image shooting mode and a video shooting mode. The body control unit 21 executes assist control when the video shooting mode is set. The second mode may include at least one of an autofocus mode that does not require manual focus operation by the photographer, and a manual focus mode in which the camera 1 does not execute assist control after a manual focus operation by the photographer.

[0049] The operation unit 25 can accept the selection of a candidate range to be set as the first range from among multiple candidate ranges. The body control unit 21 stores the selected candidate range in the body storage unit 23 as the first range setting. When executing lens drive control, the body control unit 21 reads out a range corresponding to the first range setting from the body storage unit 23. In other words, the body control unit 21 sets one range selected from the three candidate ranges as the first range. The body control unit 21 executes lens drive control based on the set first range.

[0050] The body control unit 21 can switch the movement speed of the focus lens 31a in lens drive control. As an example, the body control unit 21 may be configured to select one of three speed modes, a first speed mode, a second speed mode, and a third speed mode, as the movement speed of the focus lens 31a. In this case, the body control unit 21 sets the selected speed mode as the speed mode to be used for lens drive control in accordance with the operation received by the operation unit 25. The body control unit 21 executes lens drive control based on the set speed mode.

[0051] The first speed mode is a mode in which the focus lens 31a is moved at the average speed at which the focus lens 31a moved during a predetermined period immediately before the manual focus operation satisfies a predetermined end condition.

[0052] The second speed mode is a mode in which the focus lens 31a is moved at a preset speed.

[0053] The third speed mode is a mode in which the focus lens 31a is moved at the average deceleration rate during a predetermined period immediately before the manual focus operation satisfies a predetermined end condition. The third speed mode simulates the photographer checking the focus by slowly moving the focus lens 31a as the focus state approaches.

[0054] In the first speed mode and the third speed mode, an example of the predetermined period immediately before the manual focus operation satisfies a predetermined end condition is the period from a predetermined time (e.g., one second) before the movement of the focus lens 31a stops until the movement of the focus lens 31a stops. This predetermined period may be the same or different for the first speed mode and the third speed mode.

[0055] In steps S204 and S207, the defocus amount calculation unit 43 calculates the defocus amount of the image of a specific subject, the image of a subject detected as a single subject, or the image of a subject represented in a preselected focus detection area. The body control unit 21 repeatedly acquires position information of the focus lens 31a via the encoder 35. The body control unit 21 writes the acquired position information of the focus lens 31a to the body storage unit 23 at predetermined sampling time intervals. Note that the defocus amount calculation unit 43 may calculate the defocus amount in each step of assist control other than steps S204 and S207, or may calculate the defocus amount when assist control is not being executed.

[0056] In step S201, the determination unit 44 determines whether a first predetermined time (for example, one second) has elapsed since the movement of the focus lens 31a stopped, as a predetermined termination condition. The stop of the movement of the focus lens 31a is determined based on position information of the focus lens 31a acquired by the encoder 35. If it is determined that the first predetermined time has elapsed since the movement of the focus lens 31a stopped (S201-YES), the processing of the body control unit 21 proceeds to step S202.

[0057] In step S202, the setting unit 42 executes a subject setting process to set one subject corresponding to the image for which the defocus amount is to be calculated. The subject setting process will be described later.

[0058] In step S203, the determination unit 44 calculates the defocus amount for the image corresponding to the subject set by the setting unit .

[0059] In step S204, the determination unit determines whether the calculated defocus amount is within the second range. If it is determined that the defocus amount is within the second range (S204-YES), the drive control unit 45 terminates the assist control. In other words, if the defocus amount when the predetermined termination condition is satisfied is within the second range, the drive control unit 45 does not execute lens drive control because the lens is in focus. If it is determined that the defocus amount is not within the second range (S204-NO), the processing of the body control unit 21 proceeds to step S205. Note that in the present disclosure, the determination of "whether the defocus amount is within the second range" is used to include the detection determination of the in-focus state. That is, as an example, the determination of whether the defocus amount is within the second range may be synonymous with the detection determination of the in-focus state.

[0060] In step S205, the determination unit 44 determines whether the defocus amount for the image corresponding to the subject set by the setting unit 42 is within the first range. If it is determined that the defocus amount is within the first range (YES in S205), the processing of the body control unit 21 proceeds to step S206. If it is determined that the defocus amount is not within the first range (NO in S205), the processing of the body control unit 21 returns to step S201.

[0061] In step S206, the drive control unit 45 controls the drive motor 36 to move the focus lens 31a along the optical axis O so that the defocus amount falls within the second range. The drive control unit 45 moves the focus lens 31a based on the selected speed mode.

[0062] When the first speed mode is selected as the speed mode, the drive control unit 45 moves the focus lens 31a at the average speed of the focus lens 31a over a predetermined period of time immediately before the manual focus operation satisfies a predetermined end condition. In one example, the drive control unit 45 calculates the average speed by dividing the difference in the position of each focus lens 31a between a predetermined time (e.g., one second) before the manual focus operation is stopped and the time the manual focus operation is stopped by the predetermined time, based on the position information stored in the body storage unit 23, and moves the focus lens 31a at the average speed.

[0063] When the second speed mode is selected as the speed mode, the drive control unit 45 moves the focus lens 31a at a preset speed. As the preset speed, for example, a plurality of (e.g., 10) stages of speeds are stored in advance in the body storage unit 23, and the body control unit 21 reads out the selected speed via the operation unit 25. Note that the preset speed may be a specific speed input via the operation unit 25.

[0064] When the third speed mode is selected as the speed mode, the drive control unit 45 moves the focus lens 31a so that the deceleration of the focus lens 31a is equal to the average deceleration of the focus lens 31a over a predetermined period immediately before the manual focus operation satisfies a predetermined end condition. In one example, the drive control unit 45 first calculates the average deceleration of the focus lens 31a by performing a calculation based on the position information stored in the body storage unit 23. The drive control unit 45 assumes that the focus lens 31a moves at a constant deceleration over the predetermined period immediately before the manual focus operation satisfies the predetermined end condition, and applies the least squares method to the position data of the focus lens 31a at each time within the predetermined period to calculate the average deceleration that minimizes the square error. The drive control unit 45 then calculates the initial speed of the focus lens 31a so that the speed of the focus lens 31a becomes zero at a position where the defocus amount falls within a second range (for example, where the defocus amount is assumed to be zero) when the focus lens 31a moves while decelerating at the average deceleration from the movement speed (initial speed) of the focus lens 31a at the start of the lens drive process. The drive control unit 45 moves the focus lens 31a in accordance with the calculated initial velocity and average deceleration.

[0065] In step S207, the determination unit 44 determines whether the defocus amount is within the second range after lens drive control is performed by the drive control unit 45. If it is determined that the defocus amount is not within the second range (S207-NO), the processing of the body control unit 21 returns to step S206, and lens drive control is performed by the drive control unit 45. The processing of the body control unit 21 repeats steps S206 and S207 until it is determined that the defocus amount is within the second range (S207-YES). If it is determined that the defocus amount is within the second range (S207-YES), the processing of the body control unit 21 proceeds to step S208.

[0066] In step S208, the drive control unit 45 controls the drive motor 36 to stop the movement of the focus lens 31a, and ends the assist control.

[0067] 5 is a flowchart showing an example of subject setting processing. In step S301, the determination unit 44 determines whether the first setting mode or the second setting mode has been selected. The first setting mode is a mode that allows for a change of the focus detection area that is the target for calculating the defocus amount. If it is determined that the first setting mode has been selected (YES in S301), the processing of the body control unit 21 proceeds to step S302. If it is determined that the second setting mode has been selected (NO in S301), the processing of the body control unit 21 proceeds to step S308.

[0068] In step S302, the subject detection unit 41 detects a predetermined subject from the image data. For example, the subject detection unit 41 detects a predetermined type of subject, such as a human face, an animal, or a vehicle.

[0069] In step S303, the determination unit 44 determines whether or not a predetermined subject has been detected by the subject detection unit 41. If it is determined that a predetermined subject has not been detected (S303-NO), the processing of the body control unit 21 proceeds to step S308. If it is determined that a predetermined subject has been detected (S303-YES), the processing of the body control unit 21 proceeds to step S304.

[0070] In step S304, the determination unit 44 determines whether or not multiple subjects have been detected from the image data by the subject detection unit 41. If multiple subjects have not been detected, in other words, if it is determined that only one subject has been detected (S304-NO), the processing of the body control unit 21 proceeds to step S307. If it is determined that multiple subjects have been detected (S304-YES), the processing of the body control unit 21 proceeds to step S305.

[0071] In step S305, the body control unit 21 executes a subject selection process to select one specific subject from among a plurality of subjects and set it as the specific subject. The subject selection process will be described later.

[0072] In step S306, the setting unit 42 sets the image of the subject set as the specific subject in step S305 as the target for defocus amount determination. The setting unit 42 may also set the area in which the specific subject is detected as the focus detection area. In this case, in step S203, the defocus amount calculation unit 43 calculates the defocus amount using focus detection signals output from phase-difference focus detection pixels in the set focus detection area, and in steps S204 and S205, the determination unit 44 determines whether the defocus amount obtained in step S203 is within the second range and the first range, respectively.

[0073] In step S307, the setting unit 42 sets the image of the subject detected by the subject detection unit 41 as the target for determining the amount of defocus.

[0074] In step S308, the setting unit 42 determines the image of the subject represented in a focus detection area selected in advance from a plurality of focus detection candidate areas as the target for determining the amount of defocus.

[0075] 6 is a flowchart showing an example of a subject selection process. In the subject selection process, the setting unit 42 selects one specific subject from among a plurality of subjects and sets it as a specific subject. The image of the specific subject set in the subject selection process is set as a target for determining the defocus amount in step S306. In this embodiment, the setting unit 42 can set the specific subject in three ways.

[0076] In the first setting, the setting unit 42 selects one subject from a plurality of subjects by the closest setting and sets it as the specific subject.

[0077] In the second setting, the setting unit 42 sets, as a specific subject, the subject among multiple subjects that has the smallest defocus amount when a predetermined termination condition is satisfied (hereinafter, this setting will be referred to as the "minimum defocus amount setting"). The specific subject is set by the minimum defocus amount setting.

[0078] In the third setting, when the subject detection unit 41 detects multiple subjects from image data output after a predetermined termination condition is satisfied, the setting unit 42 sets, as a specific subject, the subject that was the same as the subject to be focused in the previous image data output before the predetermined termination condition was satisfied (hereinafter, this setting will be referred to as a “tracking subject setting”). The subject to be focused may be a subject with the smallest defocus amount or may be a subject represented in the selected focus detection area. For example, the setting unit 42 performs a predetermined tracking process, such as a KLT (Kanade-Lucas-Tomasi) tracker or ByteTrack, on the area representing the subject to be focused in the previous image data and the area representing each subject detected in the image data output after the predetermined termination condition is satisfied. This identifies the subject representing the subject to be focused from the multiple subjects in the image data output before the predetermined termination condition is satisfied. For example, the previous image data is image data obtained during a manual focus operation before the focus lens 31a stops moving.

[0079] In the above three settings, when multiple subjects are selected as subjects to be set as specific subjects, the setting section 42 may set the subject that is closer to the center of the screen as the specific subject.

[0080] The above three settings are selected via the operation unit 25. Fig. 6 shows the process when the minimum defocus amount setting is selected.

[0081] In step S401, the setting unit 42 sets the subject closest to the imaging optical system 31 as the specific subject when a first predetermined time has elapsed since the movement of the focus lens 31a due to the manual focus operation has stopped.

[0082] In step S402, the determination unit 44 determines whether or not there is an image of a subject among the multiple subjects that has a minimum defocus amount compared to the specific subject. If the subject with the minimum defocus amount is the specific subject (S402-NO), the body control unit 21 ends the subject selection process and proceeds to step S306 in Fig. 5. If the subject with the minimum defocus amount is other than the specific subject (S402-YES), the processing of the body control unit 21 proceeds to step S403.

[0083] In step S403, the setting unit 42 sets the subject for which the determining unit 44 has determined that the defocus amount is the smallest as the specific subject.

[0084] If a tracking subject has been set in the subject selection process, in step S402, the determination unit 44 determines whether the subject that was set as the focus target in the past image data can be identified from among multiple subjects detected in image data output after a first predetermined time has elapsed since the focus lens 31a stopped moving, by a predetermined tracking process, from subjects other than the specific subject, and if it is determined that the subject can be identified, in step S403, the setting unit 42 sets the subject identified in step S402 as a new specific subject. Also, in this embodiment, since the subject closest to the imaging optical system 31 is set as the specific subject in step S401, steps S402 and S403 are omitted if the closest setting has been set.

[0085] Figure 7(a) is a diagram showing, as a first example of the display content displayed on the display unit 24 of a camera 1 according to one embodiment, the display content according to the defocus amount represented by a change in icon display; (b) is a diagram showing, as a second example of the display content, the display content according to the defocus amount represented by a change in the color of the focus point frame; and (c) is a diagram showing, as a third example of the display content, the display content according to the defocus amount represented by an indicator.

[0086] The display control unit 46 causes the display unit 24 to display the first display content when the defocus amount is within the first range but not within the second range. The display control unit 46 causes the display unit 24 to display the second display content when the defocus amount is not within the first range. The display control unit 46 causes the display unit 24 to display the third display content when the defocus amount is within the second range. The first display content, the second display content, and the third display content are all different display contents. The display control unit 46 causes the display unit 24 to display the display content corresponding to the defocus amount in the first mode. Note that the display control unit 46 may also cause the display unit 24 to display the display content corresponding to the defocus amount in the second mode.

[0087] When displaying the first display content and the second display content on the display unit 24, the determination unit 44 determines whether the image of the subject is in front focus or back focus. The display control unit 46 causes the display unit 24 to display different display content depending on whether the image of the subject is in front focus or back focus.

[0088] In the first example shown in FIG. 7(a), the display control unit 46 changes the icon display to display the first, second, and third display contents differently. As an example, the third display content displays a horizontally long rectangle with a circle near the center of the rectangle to indicate a focused state. In addition, in the first display content, horizontally long rectangles are displayed on the left and right sides of the third display content, and triangles are displayed on the left or right side of each rectangle, with their apexes pointing toward the third display content. The arrangement of the triangles within the rectangles and the orientation of their apexes differ depending on whether the image is in front focus or back focus. Furthermore, in the second display content, horizontally long rectangles are displayed outside the first display content, with the third display content at the center, and the arrangement of the triangles and the orientation of their apexes differ depending on whether the image is in front focus or back focus, as in the first display content.

[0089] In a second example shown in FIG. 7(b), the display control unit 46 changes the color of the rectangular frame of the focus point to display the first display content, the second display content, and the third display content in different colors. As an example, the color of the rectangular frame of the third display content is green, yellow when the first display content is in front focus, light blue when the first display content is in back focus, red when the second display content is in front focus, and purple when the second display content is in back focus. Note that in this example, the color display is changed to match the rainbow color change, but the relationship between each display content and color may be arbitrary. As an example, the third display content may be displayed in a color other than green (e.g., red). Alternatively, each display content may be displayed using different shades of the same color.

[0090] 7(c), the display control unit 46 displays the first display content, the second display content, and the third display content differently by using an indicator to show the position of the image of the subject formed by the imaging optical system 31 relative to the in-focus state. As an example, the left side of the screen of the display unit 24 is the front focus side, the right side of the screen is the back focus side, a triangle with its apex pointing downward is the in-focus state, and the position of the image of the subject is displayed by expanding and contracting a horizontally long rectangle.

[0091] If the defocus amount calculation unit 43 cannot calculate the defocus amount, the display control unit 46 does not have to cause the display unit 24 to display these displays.

[0092] According to the above-described embodiment, the following advantageous effects can be obtained.

[0093] (1) The camera body 2 includes a control unit (drive control unit 45) that moves the focus lens so that the image formed by the imaging optical system 31 is focused on the imaging element 22 when the deviation between the image formed by the imaging optical system 31 and the imaging element 22 falls within a predetermined range after a manual focus operation. One example of the deviation between the image formed by the imaging optical system 31 and the imaging element 22 is the defocus amount. An example of the predetermined range is a first range, and when the defocus amount falls within the first range, the control unit (drive control unit 45) moves the focus lens 31a so that the defocus amount falls within a second range that is narrower than the first range. An example of the second range is the focal depth of the camera 1. In this embodiment, when the condition that the defocus amount falls within the first range is satisfied after a manual focus operation, the control unit moves the focus lens 31a so that the defocus amount falls within the second range. Therefore, when a photographer takes a photograph using manual focus, the control unit allows the photographer to freely take a photograph while assisting in focusing at a stage where focusing requires the photographer's skill, thereby enabling stable focusing regardless of the photographer's skill level.

[0094] (2) Furthermore, the camera body 2 (body control unit 21) sets a range selected from multiple candidate ranges as the predetermined range. Because the predetermined range is a condition for determining whether to start assist control, it becomes possible to flexibly change the operation of assist control according to the photographer's preferences.

[0095] (3) The camera body 2 (body control unit 21) can also selectively execute a first speed mode in which the focus lens 31a is moved at the average speed during a predetermined period immediately before the manual focus operation satisfies a predetermined end condition, or a second speed mode in which the focus lens 31a is moved at a preset speed. This allows for flexible focusing speed adjustment according to the photographer's preferences. The camera body 2 (body control unit 21) may also be selectively execute a third speed mode in which the focus lens 31a is moved at the average deceleration during a predetermined period immediately before the manual focus operation satisfies a predetermined end condition. During the predetermined period immediately before the photographer ends the manual focus operation, the movement speed of the focus lens 31a is likely to decrease in order to accurately adjust the focus. In this case, the movement of the focus lens 31a can be a constant acceleration (constant deceleration) movement, so by moving the focus lens 31a at an average deceleration during lens drive control, a smooth transition can be made from manual focus operation to focusing by the drive control unit 45.

[0096] (4) In addition, in the camera body 2 (body control unit 21), when multiple subjects are detected by the subject detection unit 41, the setting unit 42 sets as the focus detection area the area in which the subject closest to the imaging optical system 31 is detected when a predetermined termination condition is met, or the area in which the subject with the smallest defocus amount is detected when a predetermined termination condition is met, or the area in which the same subject as the subject represented in the focus detection area in the previous image data output before the termination condition is met is detected, and the control unit (determination unit 44) determines whether the defocus amount for the image corresponding to the subject represented in the focus detection area is within a first range. This enables flexible subject setting according to the photographer's preferences when multiple subjects are detected.

[0097] (5) The camera body 2 (body control unit 21) can be set to a first mode for assisting manual focus operation and a second mode that does not assist manual focus operation, and executes assist control only when the first mode of the two modes is set. This means that assist control is executed only when the photographer wants assistance with manual focus operation, allowing for flexible photography according to the photographer's preferences.

[0098] (6) The camera body 2 includes a calculation unit (defocus amount calculation unit 43) that calculates the defocus amount, which represents the deviation between the image formed by the imaging optical system 31 and the imaging element 22, and a control unit (drive control unit 45) that performs autofocus control to move the focus lens 31a based on the calculated defocus amount when the calculated defocus amount is within a predetermined range after a manual focus operation. Therefore, the camera automatically focuses after a manual focus operation, enabling stable focusing regardless of the photographer's skill level.

[0099] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0100] As an example, as a modification of the present embodiment, the camera 1 (camera body 2) may be provided with a line-of-sight detection LED and line-of-sight sensor, and the focus detection area may be selected from a plurality of focus detection candidate areas by line-of-sight detection. Alternatively, as a modification, the assist control may be performed in still image shooting mode. Alternatively, as a modification, the assist control may be a contrast method or a combination of the contrast method and the image plane phase difference method. Alternatively, as a modification, the manual focus operation for which the determination unit 44 determines whether to terminate may be a change in the focal length of a variable magnification optical system, a change in the aperture value using an aperture, or the like.

[0101] Furthermore, in this embodiment, the speed mode includes the first, second, and third speed modes, but the speed mode may include only one of the speed modes, or may include any two of the first, second, and third speed modes, or may include a speed mode other than the first, second, and third speed modes.

[0102] Furthermore, in the present embodiment, the first speed mode has been described as a mode in which focus lens 31a is moved at the average speed at which focus lens 31a moved during a predetermined period immediately before the manual focus operation satisfies a predetermined end condition, but the speed at which focus lens 31a is moved is not limited to the average speed of focus lens 31a during the predetermined period. For example, it may be the movement speed of focus lens 31a at a certain point during the predetermined period, or it may be a speed calculated by a calculation other than the average based on the movement speed of focus lens 31a during the predetermined period.

[0103] Furthermore, instead of or in addition to the first to third speed modes, the body control unit 21 may control the movement of the focus lens 31a during lens drive control so that the amount of change in the defocus amount is constant. For example, in the case of a macro lens, the change in the amount of defocus (blurring) relative to the amount of movement of the focus lens 31a may vary depending on the shooting distance. When using such a lens, even if the movement speed of the focus lens 31a is constant, the change in the amount of blur due to the movement of the focus lens 31a cannot be made constant. To move the focus lens 31a so that the amount of change in the defocus amount is constant, the body control unit 21 controls the drive of the focus lens 31a during assist control so that the amount of change in the defocus amount is constant (e.g., the average change over a predetermined period) based on, for example, the relationship between the movement speed of the focus lens 31a and the amount of change in the defocus amount during a predetermined period immediately before the movement of the focus lens 31a due to manual focus operation is stopped. When the phrase "the amount of change in the defocus amount is constant" is used, the amount of change in the defocus amount may include an error that takes into account the common technical knowledge of a person skilled in the art. The average change in the defocus amount or the movement speed of the focus lens 31a may be calculated using a coefficient indicating the relationship between the image plane movement amount and the movement amount of the focus lens 31a, and the movement amount of the focus lens 31a.

[0104] Furthermore, in this embodiment, the subject setting process is started after a predetermined time has elapsed since the movement of the focus lens 31a has stopped, but the timing for starting the subject setting process is not limited to this. [Explanation of symbols]

[0105] 1 camera 21 Body control unit 31 Imaging optical system 31a Focus Lens 41 Subject detection unit 42 Setting section 43 Defocus amount calculation unit 44 Judgment section 45 Drive control unit 46 Display control unit

Claims

1. an imaging element that captures an image formed by an imaging optical system having a focus lens; a control unit that moves the focus lens so that the image formed by the imaging optical system is focused on the imaging element when a deviation between the image formed by the imaging optical system and the imaging element falls within a predetermined range after a manual focus operation is performed; An imaging device comprising:

2. the control unit calculates a defocus amount representing a deviation between the image formed by the imaging optical system and the imaging element, determines whether the calculated defocus amount is within the predetermined range, and, if the calculated defocus amount is within the predetermined range, moves the focus lens so that the image formed by the imaging optical system is focused on the imaging element. The imaging device according to claim 1 .

3. The control unit determining whether the defocus amount when the manual focus operation satisfies a predetermined end condition is within the predetermined range; The imaging device according to claim 2 .

4. The imaging device according to claim 3 , wherein the predetermined end condition is that a first predetermined time has elapsed since movement of the focus lens by the manual focus operation has stopped.

5. The imaging device according to claim 4 , wherein the control unit changes the first predetermined time based on a speed of the focus lens when the focus lens is moved by the manual focus operation.

6. the predetermined range is a first range, when the defocus amount is within the first range, the control unit moves the focus lens so that the defocus amount is within a second range that is narrower than the first range. The imaging device according to any one of claims 2 to 5.

7. When moving the focus lens so that the defocus amount falls within the second range, the control unit controls the movement of the focus lens based on a speed at which the focus lens is moved during a predetermined period immediately before the manual focus operation satisfies the predetermined end condition. The imaging device according to claim 6 .

8. 8. The imaging device according to claim 7, wherein the control unit is capable of alternatively executing a first speed mode in which the focus lens is moved based on a speed at which the focus lens was moved during a predetermined period immediately before the manual focus operation satisfied the predetermined termination condition, and a second speed mode in which the focus lens is moved at a preset speed.

9. When moving the focus lens so that the defocus amount falls within the second range, the control unit controls the movement of the focus lens based on a change in the defocus amount when the focus lens is moved during a predetermined period immediately before the manual focus operation satisfies the predetermined termination condition. The imaging device according to claim 6 .

10. The image capturing device according to any one of claims 3 to 9, wherein the control unit determines whether the defocus amount is within the specified range for an image corresponding to a subject represented in a focus detection area pre-selected from a plurality of focus detection candidate areas within the image capturing surface of the image sensor.

11. further comprising a subject detection unit for detecting a subject, the control unit determines whether the defocus amount for the image corresponding to the subject detected by the subject detection unit is within the predetermined range. The imaging device according to any one of claims 3 to 9.

12. a setting unit that, when a plurality of subjects are detected by the subject detection unit, sets, as a focus detection area, an area in which a subject that is closest to the imaging optical system when the predetermined termination condition is satisfied among the plurality of subjects is detected; the control unit determines whether the defocus amount for the image corresponding to the subject displayed in the focus detection area is within the predetermined range. The imaging device according to claim 11.

13. a setting unit that, when a plurality of subjects are detected by the subject detection unit, sets, as a focus detection area, an area in which a subject in which the defocus amount is smallest when the predetermined termination condition is satisfied is detected among the plurality of subjects; the control unit determines whether the defocus amount for the image corresponding to the subject displayed in the focus detection area is within the predetermined range. The imaging device according to claim 11.

14. a setting unit that, when a plurality of subjects are detected by the subject detection unit from the image data output after the predetermined termination condition is satisfied, sets, as the focus detection area, an area in which the same subject as a subject represented in a focus detection area in previous image data output before the termination condition is satisfied is detected from among the plurality of subjects; the control unit determines whether the defocus amount for the image corresponding to the subject displayed in the focus detection area is within the predetermined range. The imaging device according to claim 11.

15. The imaging device according to any one of claims 2 to 14, further comprising a display control unit that causes a display content according to the defocus amount to be displayed on a display unit of the imaging device.

16. a display control unit that causes a display content according to the defocus amount to be displayed on a display unit of the imaging device, the display control unit causes the display unit to display a first display content when the defocus amount is within the first range and is not within the second range, and causes the display unit to display a second display content different from the first display content when the defocus amount is not within the first range. The imaging device according to claim 6 .

17. the control unit further determines whether the image formed by the imaging optical system is in a front-focus state, in which the image is positioned on the imaging optical system side in the optical axis direction of the imaging optical system with the imaging element as a reference, or in a back-focus state, in which the image is positioned on the opposite side from the imaging optical system side; the display control unit causes the display unit to display different display content depending on whether the image formed by the imaging optical system is in the front focus state or the back focus state. The imaging device according to claim 16.

18. 17. The imaging device according to claim 16, wherein the display control unit causes the display unit to display third display content different from each of the first display content and the second display content when the defocus amount is included in the second range.

19. The imaging device according to any one of claims 1 to 18, wherein the control unit sets a range selected from a plurality of candidate ranges as the predetermined range.

20. the control unit can set a first mode for assisting manual focus operation and a second mode for not assisting manual focus operation, only when the first mode of the first mode and the second mode is set, after the manual focus operation is performed, if a deviation between an image formed by the imaging optical system and the imaging element is within a predetermined range, the focus lens is moved so that the image formed by the imaging optical system is focused on the imaging element. An imaging device according to any one of claims 1 to 19.

21. an imaging element that captures an image formed by an imaging optical system having a focus lens; a calculation unit that calculates a defocus amount that represents a deviation between an image formed by the imaging optical system and the imaging element; a control unit that performs autofocus control to move the focus lens based on the defocus amount when the defocus amount is within a predetermined range after a manual focus operation is performed; An imaging device comprising:

Images