Imaging device, control method and program thereof

Abstract

To reduce drive of a diaphragm, while achieving simulation of the diaphragm in picking up an image of a subject even during live view display.SOLUTION: An imaging apparatus has: detection means that detects luminance of a subject; exposure control means that, on the basis of, a detection result from the detection means, adjusts at least one or more exposure parameters of a shutter speed, an f number, and photographic sensitivity and executes exposure control; and setting means that switches turn-on / -off of a simulation function for adjusting image quality of an image in performing live view display on a display to be image quality according to an opening of the diaphragm in acquiring a still image for recording. The exposure control means controls such that a settable f number discretely changes with respect to a plurality of f numbers that can be set by the imaging apparatus in relation to a change in luminance of the subject in a predetermined luminance range when the simulation function is turned on compared with a case where the simulation function is turned off.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an imaging apparatus, a control method and a program therefor, and more particularly to exposure control of an image used for live view display. [Background technology]

[0002] Conventionally, a function (live view display) for sequentially displaying images acquired continuously by imaging a subject on a display device is known. By adjusting exposure parameters such as aperture, shutter speed, and ISO sensitivity during this live view display, it is possible to simulate the change in brightness (exposure) of the image due to the adjustment. In other words, by changing the exposure during the live view display, the user can check the brightness (exposure) of the image to be obtained in advance.

[0003] Among the exposure parameters that can be changed during live view display, adjusting the aperture changes not only the brightness of the image but also the depth of field. For example, if the depth of field can be changed in response to changes in the aperture (aperture value) during live view display when shooting still images, the user can check in advance how the depth of field will change in response to changes in the aperture.

[0004] For example, Patent Document 1 proposes a technique for setting the aperture (photography aperture) when capturing a still image during live view display in response to a user operating an aperture button provided on the camera.

[0005] Furthermore, Patent Document 2 proposes a technique for setting the aperture value when acquiring an image for live view display to a value that corresponds to the aperture value (photography aperture value) when acquiring a still image. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2001-169154 A [Patent Document 2] JP 2007-158878 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the technology described in Patent Document 1, although it is possible to check the photographic aperture in response to the operation of the aperture button, it is not possible to always check the depth of field corresponding to the photographic aperture during live view display.

[0008] In contrast, if the aperture is controlled to always be the shooting aperture during live view display based on the technology described in Patent Document 2, in a shooting mode that allows aperture changes, the aperture needs to be adjusted every time the brightness (photometric value) of the subject changes. In this case, if the live view display period becomes long, the aperture drive frequency also increases, and the durability of the aperture becomes an issue. In addition, if the aperture is moved frequently, the depth of field and exposure change significantly during live view display, which may reduce the visibility of the live view display.

[0009] An object of the present invention is to suppress the driving of the aperture while realizing a simulation of the aperture when capturing an image of a subject even during live view display. [Means for solving the problem]

[0010] In order to achieve the above object, an imaging device of the present invention is an imaging device equipped with an imaging means and capable of controlling an aperture, the imaging device comprising: a detection means for detecting the brightness of a subject; an exposure control means for executing exposure control by adjusting at least one exposure parameter of a shutter speed, an aperture value, and a shooting sensitivity based on a detection result of the detection means; and a setting means for switching on / off a simulation function for adjusting the image quality of an image when a live view is displayed on a display device so as to correspond to the aperture opening when a still image for recording is obtained, the exposure control means being more effective when the simulation function is on than when the simulation function is off. Program diagram forIn the above, the aperture value that can be set by the imaging device changes discretely in response to a change in the luminance of the subject within a predetermined luminance range. The exposure control is carried out using a program diagram. The present invention is characterized by the above. Effect of the Invention

[0011] According to the present invention, it is possible to suppress the driving of the aperture while realizing a simulation of the aperture when capturing an image of a subject even during live view display. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing an example of the configuration of a digital camera 1 that is an embodiment of an imaging apparatus embodying the present invention. [Diagram 2] 5 is a flowchart showing a shooting process during live view display according to the first embodiment of the invention. [Diagram 3] FIG. 13 is a diagram for exemplarily illustrating a program diagram for still image acquisition when depth simulation according to the present invention is turned off. [Figure 4] FIG. 13 is a diagram for exemplarily explaining a program diagram for acquiring a still image when depth simulation according to the present invention is turned on; [Diagram 5] 10 is a flowchart showing a shooting process during live view display according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (First embodiment) (Basic configuration of digital camera 1) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a block diagram showing an example of the configuration of a digital camera (hereinafter simply referred to as a camera) 1 which is an embodiment of an imaging device embodying the present invention.

[0014] One or more of the functional blocks shown in FIG. 1 may be realized by hardware such as an ASIC or a programmable logic array (PLA), or may be realized by a programmable processor such as a CPU or an MPU executing software. They may also be realized by a combination of software and hardware. Therefore, even if different functional blocks are described as operating subjects in the following description, they may be realized by the same hardware as the main operating subject. As shown in FIG. 1, the camera 1 of this embodiment is a so-called lens-interchangeable imaging device equipped with a camera unit 100, an external recording medium 200, and a lens unit 300, but is not limited to this. For example, the camera unit 100 and the lens unit 300 may be configured to be integrally provided.

[0015] The shutter 102 is a light-shielding member for opening and blocking the optical path between the lens unit 300 and the image sensor 103. The image sensor 103 is a charge-accumulation type solid-state image sensor such as a CCD or a CMOS, and is an imaging means for photoelectrically converting (imaging) a light beam of a subject incident via the lens unit 300 to generate analog image data.

[0016] The electronic viewfinder 105 is an electronic finder that uses a TFT LCD (thin film transistor liquid crystal display) or an organic EL element (organic electroluminescence element) and allows the user to check the subject image.

[0017] The A / D conversion unit 106 is a conversion means for converting analog image data output from the image sensor 103 into digital image data. The image processing circuit 107 is an image processing means for performing various processes such as white balance adjustment processing and gradation processing on the digital image data output from the A / D conversion unit 106.

[0018] The timing generation circuit 108 is a timing signal generating means that generates signals (control signals such as clock signals) for operating the image sensor 103, the A / D conversion unit 106, and a D / A conversion unit 109 (described later).

[0019] Furthermore, the timing generation circuit 108 can control the accumulation of charges in the image sensor 103 by controlling the reset timing of the accumulated charges in the image sensor 103 .

[0020] The timing generating circuit 108 is controlled by a system control unit 120, which will be described later.

[0021] The memory control circuit 110 is a memory control means that controls the A / D conversion unit 106, the image processing circuit 107, the D / A conversion unit 109, and the compression / expansion circuit 111, and executes control when the acquired image data is written to the image display memory 112 or the image recording memory 113.

[0022] The image display unit 114 is a display means that employs a TFT LCD, an organic EL element, or the like, similar to the above-mentioned electronic viewfinder 105. The digital image data for display written to the image display memory 112 is converted by the D / A conversion unit 109 into analog image data for display, and then displayed on the electronic viewfinder 105 or the image display unit 114.

[0023] The image recording memory 113 is a recording means for storing image data acquired by capturing an image of a subject, and has a sufficient memory capacity for storing a predetermined number of still image data and moving image data. The image recording memory 113 can also be used as a working area for the system control unit 120, which will be described later.

[0024] The compression / expansion circuit 111 is a compression / expansion means that reads image data stored in the image recording memory 113, and compresses and expands the image data according to a predetermined image compression method and image expansion method in accordance with various applications.

[0025] The shutter control circuit 115 is a shutter control means that controls the operation of the shutter 102, and controls the operation of the shutter 102 based on the photometry result of the subject calculated by the system control unit 120. Note that the shutter 102 can be controlled in conjunction with the control of the aperture 302 described below.

[0026] The system control unit 120 is a system control means that comprehensively controls the operation of the camera 1, and functions as an exposure control means that controls exposure based on image data captured by the image sensor 103 as described above, and as a focus control means based on the focus detection result. Specifically, the system control unit 120 uses the image data captured by the image sensor 103 to control the lens position (focus control) based on contrast information of the image data acquired while shifting the position of the focus lens. As another focus control method, the system control unit 120 detects the focus state of the optical image from the phase difference between two images of the subject based on the captured image data, and controls the lens position (focus control) based on the result of this focus detection.

[0027] Furthermore, the system control unit 120 can perform photometry calculations to calculate the luminance value of the subject using image data captured by the image sensor 103. The system control unit 120 adjusts exposure parameters such as aperture value, shutter speed, and imaging sensitivity (ISO sensitivity) as exposure control when capturing an image of the subject and acquiring image data. Note that the aperture value is a parameter related to the opening of the aperture 302, the shutter speed is a parameter related to the charge accumulation time in the image sensor 103, and the imaging sensitivity is a parameter related to the amount of analog gain and digital gain.

[0028] Furthermore, the system control unit 120 has a timer function that uses a system clock (not shown) and also manages time information such as the shooting interval and the current time based on time information set by the user through the operation of the operation unit 133. Therefore, the system control unit 120 can set an appropriate exposure according to the brightness value based on various information such as the brightness of the subject, exposure control, and time described above.

[0029] The main memory 121 is a storage means for storing data related to the operation of the camera 1, such as information (program diagram based on table data or the like) on exposure (proper exposure) relative to brightness values, constants for operations executed by the camera 1, various exposure conditions, calculation formulas, etc. The non-volatile memory 123 is a storage means that can be electrically erased and stored, such as an EEPROM represented by a flash memory or the like.

[0030] Each unit described below is an operating means for inputting various operational instructions to the system control unit 120, and is configured with a button, a switch, a dial, a touch panel, a line-of-sight detection device, a voice recognition device, or a combination of these.

[0031] The mode dial 130 is an operating member used to set an arbitrary shooting mode from among a plurality of shooting modes that can be set by the camera unit 100. Note that the camera 1 can be set to a normal still image mode in which imaging is performed to obtain a still image, or a video mode in which video is recorded. Furthermore, the camera 1 of this embodiment can be set to various modes in which exposure parameters can be set automatically or manually, such as automatic, program, aperture priority, shutter speed priority, and manual, in both still image and video shooting modes.

[0032] In still image shooting, in order to check the subject, a live view display function can be realized by displaying an image (live view image) on the electronic viewfinder 105 or the image display unit 114. The live view display function is a function for sequentially displaying a plurality of image data acquired by continuously executing charge accumulation (imaging) using the image sensor 103.

[0033] The shutter switch 131 is an operating member used to instruct the start of a preparation operation for imaging a subject or an imaging operation. SW1 is turned on by a first stroke (e.g., half-pressing) of the shutter switch 131. When SW1 is turned on, the preparation operation for imaging is started, and the system control unit 120 starts focus control, exposure control, auto white balance (AWB) processing, and the like.

[0034] Furthermore, SW2 is turned on by a second stroke (e.g., full depression) of the shutter switch 131. When SW2 is turned on, imaging operation is started, and the system control unit 120 starts exposure processing and recording processing related to charge accumulation (imaging) using the image sensor 103.

[0035] In the exposure process, a signal read from the image sensor 103 is written as image data into the image recording memory 113 via the A / D conversion unit 106 and the memory control circuit 110 in response to an instruction from the system control unit 120. Then, in response to an instruction from the system control unit 120, a development process based on various calculations is executed on this image data in the image processing circuit 107 and the memory control circuit 110, and the developed image data is written into the image recording memory 113.

[0036] In the recording process, the image data after development processing read from the image recording memory 113 is compressed by the compression / expansion circuit 111 in response to an instruction from the system control unit 120. Thereafter, in response to an instruction from the system control unit 120, the image data after compression processing is written to the recording unit 201 of the external recording medium 200 via the first camera I / F 140, the first camera connector 141, the media connector 203, and the media I / F 202.

[0037] The playback switch 132 is an operating member for instructing the start of a playback process in which the acquired image data is read out from the image recording memory 113 or the external recording medium 200 and displayed on the image display unit 114 .

[0038] The operation unit 133 is an operation member used for various settings related to menu display, imaging, and playback. For example, the user can set the depth of field simulation function during live view display to on or off by operating the operation unit 133 while a menu related to the depth of field simulation function is displayed. Here, in the camera 1 according to this embodiment, it is possible to select whether or not to simulate the depth of field in a still image obtained by imaging a subject during live view display. Hereinafter, the simulation of the depth of field is simply referred to as depth simulation. When performing depth simulation, aperture control for live view display is performed as aperture control in live view display so that the image quality of the image for live view display reproduces the depth of field based on the aperture (photographing aperture) opening when the still image is acquired. That is, the depth of field based on the aperture value when the still image for recording is acquired can be confirmed during live view display. On the other hand, when depth simulation is not performed, each exposure parameter including the aperture value is controlled based on exposure control suitable for live view display, regardless of the photographing aperture when the still image is acquired.

[0039] Power switch 134 is an operating member used to switch on and off the supply of power from a power supply (battery) (not shown) to each part of camera 1. Note that by operating power switch 134, it is possible to switch on and off the supply of power not only to camera unit 100 but also to various accessory devices such as lens unit 300 and external recording medium 200 connected to camera unit 100.

[0040] The power supply control circuit 124 is a power supply control means equipped with a battery detection circuit, a DC-DC converter, a switch circuit used to switch between current-carrying blocks, etc. Based on instructions from the system control unit 120 in response to the operation of the power switch 134, the power supply control circuit 124 detects whether a battery is installed, the battery type, and the remaining battery level, and supplies the required voltage to each unit of the camera 1 for the required period of time.

[0041] The second camera I / F 150 is provided in the camera mount section 160, and is an interface for connecting the camera unit 100 and the lens unit 300. The second camera connector 151 is a connection means for electrically connecting the camera unit 100 and the lens unit 300 via the lens connector 311 and the lens I / F 310. The second camera connector 151 is capable of transmitting control signals, status signals, data signals, and the like, and supplying currents of various voltages between the camera unit 100 and the lens unit 300. The second camera connector 151 may be configured to transmit not only electrical communication, but also optical communication, audio communication, and the like.

[0042] The external recording medium 200 is an external recording device such as a memory card, a hard disk, etc. The external recording medium 200 includes a recording unit 201 configured from a semiconductor memory, a magnetic disk, etc., a media I / F 202 for the camera unit 100, and a media connector 203 for connecting to the camera unit 100.

[0043] Lens unit 300 is an optical device that is detachable from camera unit 100. Lens mount section 320 is a connection means that engages with camera mount section 160 and mechanically attaches lens unit 300 to camera unit 100. Inside lens mount section 320, a lens connector 311 that electrically connects lens unit 300 and camera unit 100 is provided.

[0044] The lens connector 311 is capable of transmitting control signals, status signals, data signals, and the like, and of receiving and supplying currents of various voltages between the lens unit 300 and the camera unit 100. The lens connector 311 may be configured to transmit not only electrical communication, but also optical communication, audio communication, and the like.

[0045] The imaging lens group 301 is an optical member including a focus lens, a zoom lens, a shift lens, etc. The diaphragm 302 is a light amount adjusting member that adjusts the amount of light of a subject light beam that passes through the imaging lens group 301 and enters the imaging element 103 side.

[0046] The aperture control circuit 303 is an aperture control means that controls the opening amount of the aperture 302 based on instructions from the system control unit 120. The system control unit 120 instructs the aperture control circuit 303 to change the opening diameter of the aperture 302 so that the opening amount corresponds to the target aperture value. The opening diameter of the aperture 302 being changed is successively detected by mutual communication between the lens unit 300 and the camera unit 100. Then, the system control unit 120 stops changing the opening diameter of the aperture 302 in response to the aperture diameter of the aperture 302 reaching the opening diameter corresponding to the target aperture value.

[0047] The lens control circuit 304 is a lens drive control means that controls the operation (drive) of the imaging lens group 301. The lens control circuit 304 is capable of detecting the lens position (focal position) of the focus lens, and transmits information on the detected lens position to the camera unit 100 side.

[0048] The lens system control unit 305 is a lens control means that performs overall control of the lens unit 300. The lens system control unit 305 has a built-in CPU, volatile memory, and non-volatile memory (not shown), and the volatile memory stores constants, variables, programs, and the like for operation. The non-volatile memory stores identification information such as a unique number related to the lens unit 300, management information, and functional information such as the maximum aperture value, minimum aperture value, and focal length. The above is the basic configuration of the camera 1.

[0049] (Camera 1 behavior during depth simulation) Hereinafter, various operations of the camera 1 when the above-mentioned depth simulation is turned on will be described with reference to the flowchart shown in Fig. 2. Fig. 2 is a flowchart showing a shooting process during a live view display according to the first embodiment of the present invention.

[0050] First, in step S201, shooting processing starts in synchronization with the start of live view display. Note that the start of live view display is started, for example, in response to the power being turned on of the camera 1. The operation of the camera 1 resulting from the start of live view display is not limited to this, and for example, the shooting processing may be started in response to the live view display being turned on by a manual operation by the user.

[0051] Next, in step S202, the system control unit 120 executes a photometric calculation at a predetermined interval based on the captured image of the image sensor 103. Any well-known method may be adopted as the photometric calculation method. In this embodiment, the entire captured image is divided into a plurality of regions, the average luminance of each block is calculated, and a predetermined weight is assigned to the average luminance of each block. The average luminance of all blocks is then set as the representative luminance of the captured image, and the representative luminance is set as the photometric result of the captured image.

[0052] Next, in step S203, the system control unit 120 checks the current setting of the depth simulation, and if the depth simulation function is off, the process proceeds to step S204, and if the depth simulation function is on, the process proceeds to step S207.

[0053] When the depth simulation function is off, in step S204, the system control unit 120 calculates exposure parameters for still image acquisition based on the photometry result of step S202. The exposure parameters for still image acquisition are calculated based on a predetermined program diagram stored in advance inside the camera 1. FIG. 3 is a diagram for illustratively explaining a program diagram for still image acquisition when the depth simulation according to the present invention is off. The program diagram illustrated in FIG. 3 is a diagram used in a program mode for normal still image shooting, and FIGS. 3(a), (b), and (c) show program diagrams for shutter speed (Tv), aperture value (Av), and shooting sensitivity (Sv), respectively.

[0054] As shown in Figures 3(a) to (c), when depth simulation is not performed, each exposure parameter changes according to the change in the brightness value Bv. For example, in the range of Bv4 or less, the shooting sensitivity (Sv) is changed according to the change in the brightness value, and in the range of brightness values ​​greater than Bv4, both the shutter speed (Tv) and the aperture value (Av) are changed so as to become higher as the brightness increases. In other words, when depth simulation is off, the configuration does not reduce the change in a specific exposure parameter according to the change in the brightness value of the subject.

[0055] Returning to FIG. 2, in step S205, the system control unit 120 calculates exposure parameters for live view display using the photometry results calculated in step S202 and a program diagram for live view display that is stored in advance inside the camera 1.

[0056] Next, if the depth simulation function is on, in step S207, the system control unit 120 calculates exposure parameters for acquiring a still image for depth simulation based on the photometry result in step S202.

[0057] Fig. 4 is a diagram for illustratively explaining a program diagram for acquiring a still image when the depth simulation according to the present invention is turned on. The program diagram shown in Fig. 4 is a program diagram used in a program mode for capturing a still image when the shooting mode executes depth simulation. Fig. 4(a), (b), and (c) respectively show programs for the shutter speed (Tv), aperture value (Av), and shooting sensitivity (Sv).

[0058] As shown in FIGS. 4(a) to 4(c), when performing depth simulation, even if the luminance value Bv changes, each exposure parameter changes so that the aperture value remains as constant as possible without changing. For example, in the range where the luminance value is greater than Bv4, as the luminance increases, the shutter speed (Tv) changes to be higher, but the aperture value changes in a stepwise manner so as to show a constant value as much as possible in response to the change in the luminance value. In other words, the system control unit 120 controls such that in the program diagram shown in FIG. 4(b), the aperture value changes discretely with respect to the change in the luminance of the subject for the entire range of aperture values that the camera 1 can set.

[0059] Specifically, as shown in FIG. 4(b), in the range of Bv4 < Bv ≤ Bv8, it is set to F2.8, in the range of Bv8 < Bv ≤ Bv12, it is set to F11, and in the range of Bv12 < Bv ≤ Bv16, it is set to F22. That is, when depth simulation is on, exposure control is performed so as to reduce the change in the aperture value in response to the change in the luminance value of the subject. That is, the number of aperture values that can be controlled by the camera 1 when depth simulation is on is less than the number of aperture values that can be set by the camera 1 when depth simulation is off. On the other hand, regarding exposure parameters other than the aperture, regardless of whether depth simulation is on or off, there is no difference such as that of the aperture value in the values that can be set with respect to the change in the luminance of the subject. Note that there may be a difference in the number of exposure parameters that can be set according to other shooting conditions such as the shooting speed during continuous shooting and the frame rate of live view display.

[0060] Note that in the program diagrams shown in each of the figures in FIG. 4, a configuration may be provided in which the program diagram has hysteresis that causes the change points of the values of each exposure parameter to be different between the change in the luminance value toward the high luminance side and the change in the luminance value toward the low luminance side.

[0061] Returning to FIG. 2, in step S208, the system control unit 120 acquires (reads out) the aperture value for control (referred to as Av1) among the exposure parameters calculated in step S207. Note that the aperture value for control (control aperture value) is the target value for controlling the aperture 302.

[0062] Next, in step S209, the system control unit 120 determines the allowable difference amount ΔAv' based on the control aperture value Av1 for still images calculated previously. When performing depth simulation, the depth simulation is performed so that the image for live view display has the same depth of field as the still image. In this case, if the difference in the depth of field in the aperture for live view display with respect to the depth of field in the shooting aperture for still image acquisition is an allowable difference, it is not necessary to match the control aperture value for still image acquisition with the aperture value for live view display image acquisition. In particular, since the aperture 302 adjusts the amount of light by mechanically driving the members, it is preferable to suppress unnecessary driving of the aperture 302 as much as possible in order to suppress deterioration in durability, responsiveness (immediate shooting performance), and continuous shooting performance.

[0063] Therefore, in the camera 1 according to this embodiment, the allowable difference amount ΔAv' is set according to the aperture value, and whether or not to newly drive the aperture 302 for live view display is determined according to whether or not the difference between the current aperture value Av0 and the aperture value Av1 for still images falls within the allowable difference amount ΔAv'. Then, in the camera 1 according to this embodiment, if the difference between the aperture value Av0 and the aperture value Av1 for still images does not fall within the allowable difference amount ΔAv', the camera 1 according to this embodiment drives the aperture for live view display in accordance with the aperture value for still images. In other words, in the camera 1 according to this embodiment, if the difference between the aperture value Av0 and the aperture value Av1 for still images falls within the allowable difference amount ΔAv', the camera 1 does not newly drive the aperture 302 for live view display.

[0064] Here, the depth of field can be calculated based on the following equations (1) and (2).

[0065]

number

[0066] As is clear from the above formulas (1) and (2), the larger the aperture value (the smaller the opening diameter of the aperture 302), the deeper (wider) the depth of field. Therefore, the larger the aperture value, the less noticeable the difference in depth of field in the image, and the smaller the impact on the depth simulation caused by the difference in aperture value between a still image and a live view display. Therefore, in the camera 1 according to this embodiment, the larger the current aperture value Av0 is, the larger the allowable difference amount ΔAv' is set.

[0067] For example, as an example of the allowable difference amount Av', the minimum resolution is set to 1 / 3 step until the rear depth of field becomes about 1 / 10 of the subject distance, and 1 step is set when the rear depth of field exceeds 1 / 10. Specifically, a scene is assumed in which a bust-up photograph is taken with a lens having a focal length of 85 mm and an aperture value of F1.2. In this case, the focal length is set to f, and the predetermined value indicating the relative distance between the camera 1 and the subject is set to 30 (i.e., a distance of 30f), and the subject is often photographed. For example, assuming that a subject is photographed at a position of 2 m, under this condition, the depth of field is about 0.22 m, which is 1 / 10 of the subject distance, at F8, so under this condition, ΔAv' is switched at F8. Note that in this example, only one threshold value is set, but multiple threshold values ​​may be set, and the hyperfocal distance may be set as the threshold value.

[0068] Returning to FIG. 2, as described above, in step S210, the system control unit 120 determines whether the difference between the previously obtained control aperture value Av1 and the current aperture value (control aperture value) Av0 is smaller than the allowable difference amount ΔAv'. If it is determined that the difference between Av1 and Av0 is smaller than the allowable difference amount ΔAv' (YES in step S210), it is determined that new aperture driving is not necessary for the depth simulation, and the process proceeds to step S212 without changing the aperture value from the current aperture value Av0. In other words, if YES is determined in step S210, the depth simulation is performed with the current aperture value Av0.

[0069] Furthermore, if it is determined that the difference between Av1 and Av0 is equal to or greater than the allowable difference amount ΔAv' (NO in step S210), it is determined that new aperture driving is necessary for depth simulation, and the control aperture value is set to Av1 in the process of step S211. In other words, if it is determined that NO in step S210, it is determined that depth simulation similar to the aperture value when acquiring a still image cannot be performed with the current aperture value Av0, and depth simulation is performed with the newly calculated aperture value Av1.

[0070] Then, in step S212, the system control unit 120 calculates exposure parameters other than the aperture value (shutter speed, shooting sensitivity) based on the aperture value (Av0 or Av1) previously determined and the photometry result (representative luminance value) obtained in step S202. Note that in step S212, the exposure parameters other than the aperture value are calculated based on the same program diagram for live view display as that described in step S205 above.

[0071] In step S206, the system control unit 120 executes exposure control based on the exposure parameters previously calculated in step S205 or step S212. That is, in step S206, the system control unit 120 controls the aperture 302 to be driven based on the previously calculated aperture value, and proceeds to the process of step S213.

[0072] Next, in step S213, the system control unit 120 determines whether or not SW1 of the shutter switch 131 is turned on. If SW1 is turned on, the process proceeds to step S214, and if SW1 is turned off, the process returns to step S202 and repeats the subsequent processes.

[0073] If it is determined that SW1 is on (YES in step S213), system control unit 120 performs distance measurement calculation for autofocus control in S214. Then, in step S215, system control unit 120 determines whether SW2 of shutter switch 131 is on. The determinations in steps S213 to S215 are repeated until SW2 is on.

[0074] Next, in step S216, the system control unit 120 executes exposure control based on the exposure parameters for still images acquired in step S204 or step S207. When performing depth simulation, if there is a difference within the allowable difference amount ΔAv' between the aperture for live view display and the shooting aperture for acquiring still images, the system control unit 120 drives the aperture 302 to match the control aperture Av1 for acquiring still images in step S217.

[0075] Next, in step S217, each part of the camera 1 is controlled to capture an image of the subject, thereby acquiring a still image. Then, in step S218, the system control unit 120 determines whether or not SW2 of the shutter switch 131 is turned off. If it is determined in step S218 that SW2 is on, the processes of steps S217 to S218 are repeated, and if it is determined that SW2 is off, the process returns to step S202. Note that if the user issues an instruction to stop the live view display or to turn off the power of the camera 1, the shooting process during the live view display illustrated in FIG. 2 is terminated.

[0076] Here, the camera 1 according to this embodiment is configured not to perform photometry again in response to SW1 of the shutter switch 131 as in the flowchart shown in Fig. 2, but is not limited to this. For example, a photometry calculation may be further performed between the determinations of steps S213 to S215, and the process (exposure adjustment) of step S216 may be performed based on the result of the photometry. In this case, although there may be a difference between the result of the depth simulation performed during live view display and the depth of field in a still image, the photometry result is unlikely to change significantly before and after SW1 is turned on.

[0077] 2, camera 1 according to this embodiment is configured to continue capturing a still image without going through photometry and distance measurement calculations if SW2 of shutter switch 131 is turned on after capturing a still image, but is not limited to this. For example, it may be configured to perform photometry and distance measurement again in response to detecting that SW2 of shutter switch 131 is turned on after capturing a still image once, and to execute exposure control and AF control in accordance with the capture of the still image.

[0078] In the above description of the present embodiment, the allowable difference amount ΔAv' is adjusted based on the aperture value during live view display and when a still image is acquired, but the present invention is not limited to this. For example, the depth of field changes depending on the focal length and the subject distance (object distance) when capturing an image of a subject in addition to the aperture value, so the allowable difference amount ΔAv' may be adjusted based on the focal length and the subject distance (object distance). Specifically, when conditions other than the focal length are the same, the depth of field is shallower when a first lens unit with a short focal length is attached than when a second lens unit with a long focal length is attached, so the allowable difference amount ΔAv' is made smaller. Also, the depth of field is shallower when the subject distance (object distance) from the camera 1 to the main subject (subject in focus) is short than when the subject distance is long, so the allowable difference amount ΔAv' is made smaller.

[0079] In addition, in the above-described embodiment, the configuration for setting the allowable difference amount ΔAv' when the depth simulation function is turned on has been described, but the present invention is not limited thereto. For example, when the focusing range for the subject is wide based on the focal length, subject distance, and aperture value, the need for performing depth simulation is low, and the need for driving the aperture in accordance with the depth simulation is also low. Therefore, a configuration may be used in which the presence or absence of depth simulation, the presence or absence or the range of the setting of the allowable difference amount ΔAv' is controlled according to the focusing range for the subject within the angle of view. For example, in the case of a so-called pan-focus state, even if the depth simulation function is turned on, the allowable difference amount ΔAv' is not calculated, and the aperture 302 may be controlled not to be driven during live view display according to the shooting aperture for acquiring a still image.

[0080] As described above, the camera 1 of this embodiment changes the aperture drive conditions according to the change in luminance of the subject depending on whether or not depth simulation is performed. Specifically, when the depth simulation function is turned on, the camera 1 according to this embodiment changes the exposure parameters other than the aperture value in response to the change in luminance of the subject with priority. Even when changing the aperture value, the camera 1 controls the aperture value that is automatically set according to the change in luminance of the subject to change discretely among the aperture values ​​that can be set by the camera 1.

[0081] Furthermore, when the depth simulation function is turned on, the camera 1 according to this embodiment determines whether or not the aperture 302 needs to be driven for the depth simulation, depending on the difference between the aperture value during live view display and the aperture value for still image acquisition. Then, the aperture 302 is driven for the depth simulation only when it is determined that the aperture 302 needs to be driven, so that the frequency of driving the aperture 302 can be suppressed. In particular, when it is determined that the difference in depth of field in the image is small between the aperture value during live view display and the aperture value for still image acquisition, it is possible to suppress new driving of the aperture 302. Therefore, the camera 1 according to this embodiment can also prevent the user from feeling uncomfortable due to the difference in depth of field between the image displayed during depth simulation and the still image.

[0082] Second embodiment In the first embodiment described above, a depth simulation is described assuming a shooting condition in which the aperture value is automatically set (for example, when the shooting mode is a program). In contrast, in this embodiment, a depth simulation under a shooting condition in which the aperture value is manually set by the user is also considered, and a configuration is described in which the adjustment method of the allowable difference amount ΔAv' is changed depending on the shooting condition. Note that the configuration and basic driving method of the camera 1, which is an imaging device according to this embodiment, are substantially the same as those in the first embodiment described above, so the same reference numerals are assigned to the respective parts and the description is omitted.

[0083] Fig. 5 is a flowchart showing the shooting process during live view display according to the second embodiment of the present invention. Note that in the flowchart shown in Fig. 5, the same processes as those in the flowchart shown in Fig. 2 described in the first embodiment above are given the same process numbers, and their explanations are omitted. Specifically, in the shooting process during live view display according to this embodiment, new processes of steps S519 and S520 are added to the shooting process according to the first embodiment described above. The processes of steps S519 to S520 will be described in detail below.

[0084] 5, if it is determined in step S203 that the depth simulation function is on, the system control unit 120 determines the shooting mode currently set in the camera 1 in step S519. If it is determined in step S519 that the shooting mode is auto (A), program (P), or shutter speed priority (Tv), the process proceeds to step S207, and the same process as in the first embodiment described above is performed. On the other hand, if it is determined in step S520 that the shooting mode is aperture priority (Av) or manual (M), the process proceeds to step S520. That is, if a shooting mode in which the aperture value may be manually set by the user is set as the shooting mode, the process proceeds to step S520.

[0085] Then, in step S520, the system control unit 120 sets a fixed allowable difference amount ΔAv', and proceeds to the process of step S210. That is, in this embodiment, in a shooting condition (shooting mode) in which the aperture value is manually set by the user, the allowable difference amount ΔAv' is set to a fixed value, so that the aperture drive frequency does not change according to the aperture value. Specifically, in this embodiment, when performing a depth simulation and the shooting mode is the aperture priority mode or the manual mode, the minimum value of the allowable difference amount ΔAv' that can be set in the shooting mode other than the above is set as a fixed value.

[0086] The value of the allowable difference amount ΔAv' in the aperture priority mode and manual mode is not limited to this, and may be equal to or less than the average value of the allowable difference amount ΔAv' that can be set when the shooting mode is a program mode or the like. In other words, assuming that the same aperture value is set, in a shooting mode in which the aperture value is manually set by the user, the allowable difference amount ΔAv' may be smaller than in a shooting mode in which the aperture value is not manually set by the user. Compared to a case in which the aperture value is automatically determined, when the user specifies the aperture value, it is highly likely that the user's intention in shooting is to place importance on changes in image quality caused by the aperture value. Therefore, by adopting the configuration of the present embodiment described above, the allowable difference amount ΔAv' is set to a fixed value that makes it easier to follow changes in the depth of field according to changes in the aperture value. With this configuration, it is possible to suppress the occurrence of differences between the user's intention in shooting and the aperture state (depth of field state) during depth simulation in live view display.

[0087] As described above, in this embodiment, the aperture tracking of the live view display image with respect to the still image during depth simulation is varied according to the shooting mode set in the camera 1, but the present invention is not limited to this. For example, the adjustable amount of the permissible difference amount ΔAv′ or the variable value and fixed value may be varied according to the shooting scene.

[0088] Specifically, when the user manually sets a shooting scene that can be set by the camera 1, or when the camera 1 automatically sets the shooting scene, the shooting scene may be determined instead of the shooting mode in step S519 described above. If the shooting scene is determined to be one that places importance on changes in image quality due to the aperture value, the process proceeds to step S520, and if the shooting scene is determined to be another shooting scene, the process proceeds to step S207. Note that shooting scenes that place importance on changes in image quality due to the aperture value include, for example, macro photography and portrait photography, and other shooting scenes may include landscape photography.

[0089] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, in the above-mentioned embodiment, the on / off state of depth simulation is determined, but the present invention is not limited to this. For example, the presence or absence of depth simulation may be automatically changed depending on various conditions such as the shooting mode and the power control state of the camera 1 (normal state, power saving state, etc.). In this case, instead of the step (S203) of determining whether depth simulation is on or off, a process for determining the above-mentioned conditions may be added.

[0090] In the above-described embodiment, the program diagram assuming a state in which the lens unit 300 is attached to the camera 1 has been described with reference to Figures 3 and 4, but the program diagram may be different when a different lens unit is attached to the camera 1. The camera 1 according to the present invention may be configured such that, even when a different lens unit is attached to the camera 1, the aperture value changes more discretely in response to changes in the luminance of the subject when the depth simulation function is turned on than when it is turned off.

[0091] In the above-described embodiment, the lens unit 300 capable of executing the depth simulation function is mounted on the camera 1, but the present invention is not limited thereto. For example, in a lens unit that drives an aperture with a motor of a type different from that of the lens unit 300, it is assumed that the division ability of the settable aperture value is coarser than that of the lens unit 300. When such a lens unit is mounted on the camera 1, if the settable aperture value of the camera 1 is further restricted, there is a risk that the tracking ability of the aperture opening diameter adjustment to the brightness change of the subject will decrease. Therefore, when such a lens unit is mounted on the camera 1, a configuration may be adopted in which the depth simulation function is restricted so that it cannot be turned on. In other words, the camera 1 according to the present invention may be configured to switch the depth simulation function on and off depending on the type of the mounted lens unit. It is only necessary that the type of the lens unit is determined using a connector provided on the camera mount unit 160 or the lens mount unit 320.

[0092] In the above-described embodiment, a digital camera has been assumed as an example of an imaging device for implementing the present invention, but the present invention is not limited to this. For example, imaging devices other than digital cameras, such as portable devices such as digital video cameras and smartphones, wearable devices, in-vehicle cameras, and security cameras, may be used.

[0093] In the above-described embodiment, the image processing circuit 107, memory control circuit 110, system control unit 120, and other units constituting camera 1 cooperate with each other to control the operation of camera 1, but the present invention is not limited to this. For example, a (computer) program following the flow shown in Fig. 2 may be stored in main memory 121 in advance. The system control unit 120 including a microcomputer may execute the program to control the operation of camera 1.

[0094] Furthermore, so long as the program has the functionality, the program may be in any form, such as object code, a program executed by an interpreter, or script data supplied to an OS.

[0095] Furthermore, the recording medium for supplying the program may be, for example, a hard disk, a magnetic recording medium such as a magnetic tape, or an optical / magneto-optical recording medium.

[0096] (Other embodiments) The present invention can also be realized by a process in which a program for realizing one or more functions of the above-mentioned embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for realizing one or more functions. [Explanation of symbols]

[0097] 1. Digital camera 100 Camera unit 113 Image recording memory 120 System control section 200 External recording media 300 Lens Unit

Claims

1. An imaging device including an imaging means and capable of controlling an aperture, A detection means for detecting the luminance of a subject; an exposure control means for performing exposure control by adjusting at least one exposure parameter selected from a shutter speed, an aperture value, and a photographing sensitivity based on a detection result of the detection means; a setting means for switching on / off a simulation function for adjusting the image quality of an image displayed in a live view on a display device so as to correspond to the aperture of the diaphragm when a still image for recording is acquired; having an exposure control means for performing the exposure control when the simulation function is turned on by using a program chart in which the settable aperture values ​​change discretely for a plurality of aperture values ​​that can be set by the imaging device in response to changes in the luminance of the subject within a predetermined luminance range, rather than a program chart used when the simulation function is turned off.

2. 2. The imaging device according to claim 1, wherein the exposure control means controls so that when the simulation function is turned on, the change in exposure parameters other than the aperture value is greater for the same amount of change in the luminance of the subject within the specified luminance range than when the simulation function is turned off.

3. 3. The imaging device according to claim 2, wherein the number of aperture values ​​that can be set in the imaging device when the simulation function is turned on is smaller than the number of aperture values ​​that can be set in the imaging device when the simulation function is turned off.

4. The imaging device according to claim 2 or 3, characterized in that the number of values ​​of predetermined exposure parameters other than aperture value that can be set in the imaging device when the simulation function is turned on is the same as the number of values ​​of the predetermined exposure parameters other than aperture value that can be set in the imaging device when the simulation function is turned off.

5. 5. The imaging device according to claim 1, wherein the exposure control means controls the change of the photographing sensitivity in accordance with a change in the luminance of the subject in a range different from the predetermined luminance range, prior to the change of the aperture value and the shutter speed.

6. 6. The imaging device according to claim 1, wherein the setting means switches the simulation function on and off in response to a manual operation by a user while a menu related to the simulation function is displayed on a display means.

7. 6. The image pickup apparatus according to claim 1, wherein the setting unit switches the simulation function on and off in accordance with a photography mode that can be set by the image pickup apparatus.

8. 6. The image pickup apparatus according to claim 1, wherein the setting unit switches the simulation function on and off depending on a type of a lens unit attached to the image pickup apparatus.

9. A method for controlling an imaging apparatus having an imaging means and capable of controlling an aperture, comprising the steps of: an exposure control step of performing exposure control by adjusting at least one exposure parameter among a shutter speed, an aperture value, and a photographing sensitivity based on the luminance of a subject; A control method for an imaging device, characterized in that, in the exposure control step, when a simulation function is turned on to adjust the image quality of an image when displayed in live view on a display device so that it corresponds to the aperture opening when a still image for recording is obtained, the exposure control is performed by using a program chart in which the settable aperture values ​​change discretely for a plurality of aperture values ​​that can be set by the imaging device in response to changes in the luminance of a subject within a predetermined luminance range, rather than a program chart used when the simulation function is turned off.

10. A computer-readable program for causing a computer to execute the control method according to claim 9.

Images