Imaging device

Abstract

This solution addresses the issue where the brightness of the live view image changes due to the frequent activation of the aperture of the camera lens to compensate for exposure changes when the brightness of the subject changes. [Solution] The system comprises an image sensor that captures an image of a subject formed by an optical system having an aperture and outputs a signal, a display unit that displays the generated image, an operation unit that instructs imaging, a calculation unit that calculates a first aperture value which is the aperture value for shooting, and a control unit that sets a second aperture value which is the aperture value for shooting a through-image display that displays images repeatedly captured by the image sensor on the display unit, wherein the control unit does not change the second aperture value when the first aperture value is changed in accordance with a change in the brightness of the subject, and the second aperture value is within the allowable range based on the changed first aperture value.

Description

Technical Field

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

Background Art

[0002] There is known a camera that displays an image for a monitor called a live view image. Also, when the brightness of a subject changes, the aperture of a photographing lens is frequently driven for exposure correction (see Patent Document 1). Therefore, there has been a problem that the brightness of the live view image screen changes due to the frequent driving of the aperture.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] [[ID=3l]] According to one aspect of the present invention, an imaging device includes an imaging element that captures an image of a subject formed by an optical system having an aperture and outputs a signal, a display unit that displays an image generated based on the signal, an operation unit that instructs imaging by the imaging element by an operation, a calculation unit that calculates a first aperture value that is a value of an aperture for photographing based on the operation of the operation unit based on the signal, and a control unit that sets the first aperture value and a second aperture value that is a value of an aperture for through-image display that displays the image based on the signal repeatedly captured by the imaging element on the display unit, and when the first aperture value is changed in response to a change in the brightness of the subject, the control unit does not change the second aperture value if the second aperture value is within an allowable range based on the changed first aperture value.

Brief Description of the Drawings

[0005] [Figure 1] It is a perspective view illustrating a camera system. [Figure 2]This is a block diagram illustrating the main components of the camera shown in Figure 1. [Figure 3] Figures 3(a) to 3(d) illustrate the first and second aperture values. [Figure 4] Figures 4(a) to 4(d) illustrate the first and second aperture values. [Figure 5] Figures 5(a) to 5(c) illustrate the first and second aperture values. [Figure 6] This flowchart illustrates an example of the processing performed by the body-side control unit when in live view mode. [Modes for carrying out the invention]

[0006] The following describes embodiments for carrying out the invention with reference to the drawings. Figure 1 is a perspective view of a camera system 1 before an interchangeable lens 3 is attached to the camera body 2 according to one embodiment of the invention. The camera body 2 and the interchangeable lens 3 are coupled by a bayonet structure of the body-side mount 210 and the lens-side mount 310. When the camera body 2 and the interchangeable lens 3 are coupled, the terminals provided on each mount make physical contact with each other, electrically connecting the camera body 2 and the interchangeable lens 3. As will be described later using Figure 2, the camera body 2 includes an operating member 280 such as a shutter release button and an image sensor 260. Figure 1 illustrates a camera system 1 with interchangeable lenses, but the camera system 1 may also be a camera or video camera with an integrated camera body and lens.

[0007] Figure 2 is a block diagram illustrating the main components of the camera system 1 according to the first embodiment. <Interchangeable Lenses> The interchangeable lens 3 includes a lens-side mount 310, a lens-side control unit 330, a lens-side communication unit 340, a lens-side memory unit 350, a shooting lens 360, a lens drive unit 370, and an aperture drive unit 380.

[0008] The annular lens-side mount 310 is provided with a lens-side terminal holding portion 320. The lens-side terminal holding portion 320 has multiple lens-side terminals arranged in an arc shape around the optical axis O. The multiple lens-side terminals include, for example, a mounting detection terminal that informs the camera body 2 that the interchangeable lens 3 has been attached to the camera body 2, multiple communication terminals used for communication between the interchangeable lens 3 and the camera body 2, a power supply terminal for supplying power from the camera body 2 to the interchangeable lens 3, and a grounding terminal.

[0009] The lens-side control unit 330 consists of a microcomputer and its peripheral circuits. The lens-side control unit 330 controls each part of the interchangeable lens 3 by executing a control program stored in the lens-side memory unit 350. The lens-side control unit 330 is connected to the lens-side communication unit 340, the lens-side memory unit 350, the lens drive unit 370, and the aperture drive unit 380.

[0010] The lens-side communication unit 340 communicates with the body-side communication unit 240 when the interchangeable lens 3 is attached to the camera body 2. The lens-side communication unit 340 is connected to the lens-side control unit 330 and the lens-side terminal described above. Communication between the lens-side communication unit 340 and the body-side communication unit 240 via the contacted lens-side terminal and body-side terminal allows the lens control unit 330 to issue instructions for movement of the lens 361, etc., as described later. In addition, the camera body 2 sends a transmission request to the lens control unit 330 of the interchangeable lens 3 to transmit information within the interchangeable lens 3, such as information indicating the status of the lens drive unit 370, to the camera body 2.

[0011] The information indicating the state of the lens drive unit 370 mentioned above is, for example, information indicating that the lens drive unit 370 is driving the lens 361. On the other hand, data indicating the position of the lens 361 after movement, the state of the drive unit in the interchangeable lens 3, data read from the lens-side memory unit 350, and information regarding shooting distance and magnification are transmitted to the camera body 2 as information within the interchangeable lens 3.

[0012] The lens-side memory unit 350 is composed of a non-volatile storage medium. The recording and reading of data in the lens-side memory unit 350 is controlled by the lens-side control unit 330. In addition to storing control programs executed by the lens-side control unit 330, the lens-side memory unit 350 also stores data indicating the model name of the interchangeable lens 3 (also referred to as model name information), and data indicating the optical characteristics of the photographic lens 360, such as focal length and aberration information. The data stored in the lens-side memory unit 350 may also include tolerance values ​​based on the difference in optical characteristics between the first aperture value and the second aperture value, which will be described in detail later.

[0013] The photographic lens 360 directs subject light to the imaging surface of the image sensor 260 of the camera body 2. The optical axis O of the photographic lens 360 coincides with the centers of the lens-side mount 310 and the body-side mount 210. The photographic lens 360 is composed of multiple lenses 361, including a focusing lens and a zoom lens, and an aperture 362. Although lens 361 has multiple lenses, it is simplified and shown as a single lens in Figure 2. At least a portion of the photographic lens 360 is configured to move forward and backward in the direction of the optical axis O by the lens drive unit 370 or manual operation. For example, the focusing lens is configured to move forward and backward in the optical axis O direction by the lens drive unit 370. As the focusing lens moves, the focal position of the photographic lens 360 is adjusted.

[0014] The aperture 362 is a so-called aperture diaphragm with multiple aperture blades, and by driving the aperture blades, it changes the aperture diameter (aperture value) of the photographic lens 360 and adjusts the amount of light incident on the image sensor 260. The aperture drive unit 380 drives the aperture blades and changes the aperture diameter (aperture value). The aperture drive unit 380 is composed of a stepping motor and an aperture drive mechanism. Based on instructions from the lens-side control unit 330, the aperture drive unit 380 drives the aperture blades of the aperture 362 to change the aperture diameter. The aperture drive unit 380 also detects the aperture value of the aperture 362 by measuring the amount of drive of the aperture blades using an encoder or pulse counter provided near the aperture blades.

[0015] The lens driving unit 370 is constituted by a lens driving mechanism including a stepping motor. The lens driving unit 370 moves the focusing lens constituting the lens 361 along the direction of the optical axis O by a driving signal output from the lens side control unit 330. The moving direction, moving amount, moving speed, etc. of the focusing lens are instructed from, for example, the body side control unit 230. The lens driving unit 370 detects the position of the focusing lens by an encoder provided near the lens or the driving steps of the stepping motor, etc.

[0016] <Camera body> The camera body 2 has a body side mount 210, a body side control unit 230, a body side communication unit 240, a power supply unit 250, an imaging element 260, a signal processing unit 270, an operation member 280, and a display unit 290. Further, the recording unit 100 is configured to be detachable from the camera body 2.

[0017] A body side terminal holding part 220 is provided on the annular body side mount 210. The body side terminal holding part 220 has a plurality of body side terminals. The plurality of body side terminals include, for example, a mounting detection terminal for transmitting that the interchangeable lens 3 is mounted, a plurality of communication terminals used in communication between the camera body 2 and the interchangeable lens 3, a power supply terminal for supplying power from the camera body 2 to the interchangeable lens 3, and a grounding (ground) terminal.

[0018] The body side control unit 230 has a storage unit 235 and is constituted by a microcomputer and its peripheral circuits, etc. The body side control unit 230 executes a control program stored in the storage unit 235 to control each part in the camera body 2. The body side control unit 230 is connected to the body side communication unit 240, the power supply unit 250, the imaging element 260, the signal processing unit 270, the operation member 280, the display unit 290, the recording unit 100, and the above-described mounting detection terminal.

[0019] The storage unit 235 provided in the body side control unit 230 has its data recording and reading controlled by the body side control unit 230. In addition to storing the control programs and the like executed by the body side control unit 230, the storage unit 235 can store the model name information of the interchangeable lens 3 received by the body side communication unit 240, data indicating the optical characteristics of the interchangeable lens 3, and the like.

[0020] The body side communication unit 240 performs the above-described communication with the lens side communication unit 340 when the interchangeable lens 3 is attached to the camera body 2. The body side communication unit 240 is connected to the body side control unit 230 and the above-described communication terminals. The power supply unit 250 converts the voltage of a battery (not shown) into a voltage used in each part of the camera system 1 and supplies it to each part of the camera body 2 and the interchangeable lens 3. The power supply unit 250 can switch the power supply on and off for each power supply destination according to an instruction from the body side control unit 230. The power supply unit 250 is connected to the body side control unit 230 and the above-described power supply terminals.

[0021] The imaging device 260 is a solid-state imaging device such as a CMOS image sensor or a CCD image sensor in which pixels are two-dimensionally arranged in the row direction and the column direction. The imaging device 260 captures a subject image on the imaging surface according to a control signal from the body side control unit 230 and outputs an imaging signal. The imaging device 260 is connected to the body side control unit 230 and the signal processing unit 270.

[0022] The imaging device 260 has pixels for image generation (referred to as imaging pixels) and pixels for focus detection (referred to as focus detection pixels) arranged on the imaging surface. The signal generated by the imaging pixels (hereinafter referred to as the imaging pixel signal) is used by the signal processing unit 270 described later to generate image data. In addition, the signal generated by the focus detection pixels (hereinafter referred to as the focus detection pixel signal) is used by the signal processing unit 270 described later for a focus detection process to detect the imaging state of the image formed by the interchangeable lens 3 on the imaging surface of the imaging device 260, that is, the defocus amount described later. Furthermore, the image sensor 260 may be configured to have multiple photoelectric conversion units and to output pixels that can be used for both imaging and focus detection.

[0023] The signal processing unit 270 performs predetermined image processing on the imaging pixel signals output from the imaging pixels of the image sensor 260 to generate image data. The generated image data is recorded in a predetermined file format in the recording unit 100 or used for image display by the display unit 290. The signal processing unit 270 is connected to the body-side control unit 230, the image sensor 260, and the display unit 290.

[0024] Furthermore, the signal processing unit 270 uses the focus detection pixel signal output from the focus detection pixel of the image sensor 260 to calculate the amount of defocus of the interchangeable lens 3 using a phase difference detection method. The amount of defocus is the difference between the position of the image of the subject formed by the interchangeable lens 3 (image plane) and the position of the imaging plane of the image sensor 260. Based on the calculated amount of defocus, the signal processing unit 270 calculates the amount of movement of the focusing lens to the in-focus position, which is the position of the focusing lens when the image of a specific subject is formed on the imaging plane of the image sensor 260 by the interchangeable lens 3.

[0025] The body-side control unit 230 also functions as a photometering calculation unit. The body-side control unit 230 detects the brightness information (Bv value) of the subject based on the imaging pixel signal input from the image sensor 260 to the signal processing unit 270. Based on the Bv value and the program diagram information stored in the memory unit 235, the body-side control unit 230 determines the aperture value (Av value), shutter speed (Tv value), and shooting sensitivity (Sv value). Shooting sensitivity, also known as ISO sensitivity, is the gain during photoelectric conversion in the image sensor 260. The Av value, Tv value, and Sv value are values ​​calculated by apex calculation depending on the shooting mode.

[0026] The recording unit 100 is a memory card, which is a non-volatile storage medium. The recording unit 100 is inserted into an unillustrated slot located on the inside of the camera body 2's exterior. The recording unit 100's recording and reading of image data is controlled by the body-side control unit 230.

[0027] The operating components 280, including the shutter release button and various operation switches, are provided on the exterior surface of the camera body 2. By operating the operating components 280, the user can set shooting modes and live view modes, as described later. Shooting mode settings include options such as whether to capture still images or videos, whether to have the camera automatically determine all of the Av, Tv, and Sv values, or whether the user determines some or all of these values. The shutter release button has two pressing stages: half-press and full-press. When the button is fully pressed, an image capture command is given to the body-side control unit 230, and the image captured by the image sensor 260 and generated by the signal processing unit 270 is stored in the recording unit 100. The half-press operation is a press down operation to about half the amount of the full-press operation, and the shooting preparation operation is performed.

[0028] The display unit 290 includes, for example, an organic EL or liquid crystal display panel. The display unit 290 displays images based on image data processed by the signal processing unit 270, as well as operation menu screens, etc., based on instructions from the body-side control unit 230. The display unit 290 is connected to the body-side control unit 230 and the signal processing unit 270. Furthermore, the display unit 290 can also dynamically and sequentially display image data based on signals repeatedly captured by the image sensor 260, in a so-called live view image display. This live view image display may have lower image quality than the image generated by capturing by fully pressing the shutter release button. Live view image display is performed when the camera system 1 is powered on in shooting modes other than playback mode or settings mode. In this embodiment, the live view image display has the following three live view modes, and any of the live view modes can be selected.

[0029] The first Live View mode displays the Live View image with an emphasis on ease of viewing, without reflecting various user-defined settings during shooting. The first Live View mode generates the Live View image and performs exposure calculations based on the image capture pixel signal, and performs focus detection processing based on the focus detection pixel signal. User-defined shooting settings include shutter speed, aperture value, and exposure settings to achieve the user's desired image effect. When the aperture value is set high (the aperture opening is narrowed), the first live view mode displays a bright image to prioritize the visibility of the live view image without stopping down the aperture to the set value. In other words, the first live view mode only stops down the aperture to a predetermined value (the second aperture value, the live view aperture value, described later) that allows for accurate distance measurement calculations from the imaging signal that generates the live view image. This first live view mode displays the live view image in a state as close as possible to that of an optical viewfinder (so-called OVF). Therefore, in the first live view mode, even if the user has set exposure compensation, the live view image is displayed without considering the exposure compensation set by the user. More specifically, even if the user has set an exposure compensation of -1 / 3 stop, the image displayed in live view will not be a dark image.

[0030] The second live view mode displays a live view image that reflects the various settings made by the user during actual shooting. Similar to the first live view mode, this mode generates a live view image and performs exposure calculations based on the image capture pixel signal, and performs focus detection processing based on the focus detection pixel signal. In the second live view mode, the exposure at the time of actual shooting is simulated based on the settings at the time of shooting, and the image is displayed on the display unit 290. However, in order to enable distance measurement calculations from the image capture signal that generated the live view image, the aperture value is only stopped down to a predetermined value that allows for distance measurement (the second aperture value, the live view aperture value, which will be described later). The image displayed as a live view image is made darker through image processing. As mentioned above, the first live view mode does not necessarily reflect the user's settings, but in the second live view mode, for example, if the user has set exposure compensation, the live view image will be displayed reflecting the exposure compensation set by the user. More specifically, if the user has set an exposure compensation of -1 / 3 stop, the image displayed in live view will be 1 / 3 stop darker.

[0031] The third Live View mode reflects all user-defined shooting settings in the displayed Live View image. In the third Live View mode, no calculations are performed for actual shooting. If a large aperture value is set for actual shooting in the third Live View mode, the camera will stop down to the set aperture value when taking the image. As a result, the image displayed in Live View will be darker, but the depth of field for the set aperture value can be checked, allowing for a preview of the actual shot.

[0032] In this embodiment, when the camera system 1 described above is set to either the first or second live view mode, the display unit 290 displays the live view image, and the body-side control unit 230 calculates the exposure and defocus amount based on the image capture pixel signal and the focus detection pixel signal. This exposure calculation and defocus amount calculation are repeated while the live view is displayed. The calculated exposure calculation result is used for various settings for subsequent image capture of live view images and shooting by pressing the release button. The defocus amount calculated while the live view image is displayed is used to instruct the focusing lens to move when the release button is half-pressed. Below, we will explain the case in which the aperture value at the time of shooting is automatically determined by the body-side control unit 230 from the exposure calculation result, depending on the settings of the operation unit. That is, the shooting mode is set to program automatic exposure calculation mode, shutter speed priority exposure calculation mode, or full auto mode in which sensitivity settings are also calculated.

[0033] <Two aperture values> The body-side control unit 230 sets two aperture values. The first aperture value is the first aperture value (also called the shooting aperture value) that is applied when the release button constituting the operating member 280 is pressed (fully pressed) and image is taken (actual shooting), and is a value based on the apex exposure calculation described above.

[0034] The second aperture value, which will be explained in more detail later using Figures 3-5, is the second aperture value (also called the live view aperture value) applied when taking images for displaying the live view image on the display unit 290, that is, when calculating the exposure and the amount of defocus. The second aperture value should be smaller (wider) than the first aperture value. This is because changing the aperture value of the shooting lens 360 (aperture 362) changes the depth of field (the tolerance range for distance measurement) of the subject image. When the aperture value of aperture 362 is small (wider), the depth of field is shallow, and when the aperture value is large (closer), the depth of field is deep. For this reason, if the defocus amount is calculated using an aperture value larger (closer) than the aperture value set for the actual shooting, an accurate value cannot be calculated. Furthermore, since the best image plane due to aberrations in the shooting lens 360 changes depending on the aperture value, it is even better if the aperture value used when calculating the defocus amount (second aperture value) is the same as the aperture value used during shooting (first aperture value). The first aperture value changes according to the exposure calculation in response to changes in the subject's brightness. However, if the subject's brightness changes frequently, and the second aperture value displayed in the live view is frequently changed in accordance with the change in the first aperture value, the noise (drive noise) emitted by the aperture drive unit 380 can easily become a problem. In addition, flickering of the live view image due to sudden changes in the brightness of the image displayed on the display unit 290 can also easily become a problem.

[0035] In this embodiment, the body-side control unit 230 calculates control values, including the first aperture value, based on the metering value when in live view mode, and stores each of the calculated values ​​in the storage unit 235. When the release button is fully pressed, the body-side control unit 230 instructs the aperture drive unit 380 to drive the aperture 362 to the first aperture value stored in the storage unit 235, and takes a picture to acquire an image for recording.

[0036] Furthermore, in this embodiment, even if the brightness of the subject changes frequently, the body-side control unit 230 calculates a second aperture value that changes less than the first aperture value so that the aperture 362 is not frequently driven when capturing a live view image. During live view display, the aperture 362 is driven to the second aperture value to acquire a live view image.

[0037] When the body-side control unit 230 acquires a live view image, it recalculates control values, including the first aperture value, based on the new metering values, and updates and stores the calculated values ​​in the storage unit 235. The body-side control unit 230 also recalculates the second aperture value and updates and stores the calculated value in the storage unit 235. If the release button is not pressed (fully pressed), the body-side control unit 230 drives the aperture 362 so that its aperture value becomes the second aperture value stored in the storage unit 235, and acquires a live view image.

[0038] <Calculation of the first and second aperture values> The calculation of the first and second aperture values ​​in Live View mode will be explained in more detail below. Figures 3(a) to 3(d) illustrate the first and second aperture values. The upper line shows the first aperture value (aperture value for shooting), and the lower line shows the second aperture value (aperture value for live view). The units for the first and second aperture values ​​are exposure calculation values ​​(apex calculation values), with the widest aperture value set to Av1 and the smallest aperture value shown up to Av6. The widest and minimum values ​​of aperture 362 may be changed as appropriate for each model of interchangeable lens 3, for example. The first and second aperture values ​​calculated by the body-side control unit 230 are represented by the position of the triangle (▽) on each line. In the example shown in Figure 3(a), the calculated first aperture value (aperture value for shooting) is Av4, and the second aperture value (aperture value for live view) is Av3.5.

[0039] The body-side control unit 230 controls the image sensor 260 by accumulating data, for example, in synchronization with the frame rate of the live view display. Then, as described above, it determines the Bv value based on the signal value (also called the photometric value) of the imaging pixel signal generated by the imaging pixels of the image sensor 260 through accumulation. Furthermore, it determines the first aperture value (Av value), shutter speed (Tv value), and sensitivity (Sv value) based on the Bv value and the program diagram information stored in the memory unit 235. The first aperture value (Av value), shutter speed (Tv value), and sensitivity (Sv value) are stored in the memory unit 235 as control values. The body-side control unit 230 calculates a control value including such a first aperture value (Av value) each time the imaging pixel signal from the image sensor 260 is input to the signal processing unit 270, and updates and records the calculated control value in the storage unit 235.

[0040] When the camera body's control unit 230 calculates the initial first aperture value (Av value) in live view mode, it sets an allowable range (indicated by a dashed rectangle) that is wider than the first aperture value (Av value), for example, by one stop in the apex value. As described above, the control unit 230 calculates the amount of defocus based on the focus detection pixel signal of the live view image, and sets the second aperture value to an aperture value that results in a shallower depth of field for the subject image than the first aperture value set for shooting. In this embodiment, the range between the first aperture value itself and one stop wider than the first aperture value is used as the range for setting the second aperture value, and this is referred to as the allowable range. The initial second aperture value (Av value) is then determined to be the midpoint of this allowable range (an aperture value 1 / 2 stop from the widest side). In the example shown in Figure 3(a), the first aperture value (aperture value for shooting) is Av4, so the second aperture value (aperture value for live view) is determined to be Av3.5, which is the midpoint between Av4 and Av3, which is one stop wider. While a one-stop apex value is given as an example of the acceptable range, it is not limited to one stop; it could be two stops or even half a stop. Alternatively, the upper limit (small diameter side) and lower limit (wide-open side) of the acceptable range may differ depending on the information of interchangeable lens 3 (focal length, maximum aperture value, etc.). Furthermore, an example is given in which the midpoint of the acceptable range is determined as the second aperture value (Av value). However, a value that is not exactly the midpoint of the range (for example, 1 / 3 stop or 5 / 6 stop from the widest aperture) may also be used as the second aperture value (Av value).

[0041] Figure 3(b) illustrates the first and second aperture values ​​when the brightness of the subject is brighter than in Figure 3(a). As explained in Figure 3(a), the body-side control unit 230 determines the first aperture value (Av value).

[0042] In the state shown in Figure 3(b), the first aperture value (shooting aperture value) is changed to a smaller diameter (larger Av value) than in the state shown in Figure 3(a), and the first aperture value is Av4.4. Accordingly, the tolerance range of the second aperture value based on the first aperture value (shown as a dashed rectangle) also moves to the smaller diameter side. The body-side control unit 230 determines whether the second aperture value (Av value) determined in the previous state shown in Figure 3(a) is included in the tolerance range (shown as a dashed rectangle in Figure 3(b)) based on the first aperture value calculated this time. Since the Av3.5 set in the previous state (Figure 3(a)) is within the tolerance range of one stop this time (Av3.4~4.4), the second aperture value (Av value) in Figure 3(a) is not changed and is maintained at Av3.5. By maintaining the second aperture value (Av value), the frequency of driving the aperture 362 in live view mode can be reduced.

[0043] Figure 3(c) illustrates the first and second aperture values ​​when the brightness of the subject is even brighter than in Figure 3(b). The body-side control unit 230 determines the first aperture value (Av value).

[0044] In the state shown in Figure 3(c), the first aperture value (Av value) is changed to a smaller diameter than in the state shown in Figure 3(b), and the first aperture value is Av4.8. The allowable range of the second aperture value based on the first aperture value (shown by a dashed rectangle) also moves to a smaller diameter. The body-side control unit 230 changes the second aperture value (Av value) to a smaller diameter because the second aperture value (dotted triangle Av3.5) in Figure 3(a), which it has been maintaining, falls outside the allowable range of the second aperture value based on the first aperture value (Av4.8) calculated this time (Av3.8~4.8 shown by a dashed rectangle in Figure 3(c)). The second aperture value (Av value) is determined to be Av4.3 (shown by a solid triangle), which is the midpoint of the allowable range of the second aperture value (Av3.8~4.8) calculated this time.

[0045] Figure 3(d) illustrates the first and second aperture values ​​when the brightness of the subject is even brighter than in Figure 3(c). The body-side control unit 230 determines the first aperture value (Av value).

[0046] In the state shown in Figure 3(d), the first aperture value (Av value) is changed to a smaller value than in the state shown in Figure 3(c), and the first aperture value is Av5.8. The allowable range of the second aperture value based on the first aperture value (shown as a dashed rectangle) also moves to the smaller value side. The body-side control unit 230 changes the second aperture value (Av value) to a smaller value side because the second aperture value (Av value) in Figure 3(c), which was determined in the previous calculation, falls outside the allowable range of the second aperture value (shown as a dashed rectangle in Figure 3(d)) Av4.8~5.8 based on the first aperture value (Av4.8) calculated this time, and attempts to determine the second aperture value (Av value) as the midpoint of a newly hypothesized range.

[0047] However, in this embodiment, the smaller diameter side of the second aperture value (Av value) is limited to Av5. The reason for setting a limit on the smaller diameter side of the second aperture value (Av value) is that the detection accuracy of the image shift amount (phase difference) described above decreases as the aperture diameter of the aperture 362 decreases. Since a decrease in the detection accuracy of phase difference leads to a decrease in the focus detection accuracy, in this embodiment, a limit is set on the smaller diameter side of the second aperture value (Av value) (Av5 in this example) to suppress the decrease in focus detection accuracy in live view mode. Therefore, in Figure 3(d), where the brightness of the subject is even brighter than in Figure 3(c), the acceptable range for the second aperture value is Av4.8 to 5.8, as shown by the dashed rectangle, with the intermediate value being Av5.3. However, the second aperture value that is actually set is the smaller limit value Av5, as shown by the black-filled triangle (▼). Furthermore, the limit on the smaller diameter side of the second aperture value (Av value) may be changed as appropriate for each model of interchangeable lens 3.

[0048] Figure 4(a) is a diagram illustrating the first and second aperture values ​​when the brightness of the subject is even brighter than in Figure 3(d). The body-side control unit 230 determines the first aperture value (Av value).

[0049] In the state shown in Figure 4(a), the first aperture value (Av value) is changed to a smaller value than in the state shown in Figure 3(d), and the first aperture value is Av6.8. The allowable range of the second aperture value based on the first aperture value (shown by the dashed rectangle) also moves to the smaller value side. The body-side control unit 230 maintains the second aperture value (Av5), which is the limit on the smaller diameter side of the second aperture value (Av5), even though the maintained second aperture value (Av value) is outside the allowable range of the second aperture value based on the first aperture value calculated this time (shown by the dashed rectangle in Figure 4(a)) Av5.8~6.8. Even if the brightness of the subject becomes even brighter than in the state shown in Figure 3(d), the second aperture value in Figure 4(a) remains at the limit on the smaller diameter side, Av5, as shown by the black triangle (▼).

[0050] By the way, if the smaller diameter of the second aperture value (Av value) is restricted, there is a risk that the live view image displayed on the display unit 290 will become brighter (overexposed). In the first live view mode described above, in order to suppress such changes in the brightness of the display screen, the body-side control unit 230 may shorten the exposure time (accumulation time, Tv value) of the image sensor 260 or lower the sensitivity (Sv value). By such control, changes in the brightness of the live view image displayed on the display unit 290 can be suppressed. As mentioned above, in the first live view mode, user settings (such as exposure compensation) are not reflected in the process of suppressing such changes in the brightness of the display screen, but in the second live view mode, the exposure time (accumulation time, Tv value) and sensitivity (Sv value) are determined taking into consideration user settings (such as exposure compensation).

[0051] Figure 4(b) illustrates the first and second aperture values ​​when the brightness of the subject is darker than in Figure 4(a).

[0052] In the state shown in Figure 4(b), the first aperture value (Av value) is changed to the open side compared to the state shown in Figure 4(a), and the first aperture value is Av6. Accordingly, the tolerance range of the second aperture value based on the first aperture value (shown as a dashed rectangle) also moves to the open side. The body-side control unit 230 maintains the second aperture value (Av value) at the limit value Av5 because Av5, which was set and maintained in Figure 4(a) last time, is within the tolerance range of the second aperture value based on the first aperture value calculated this time (shown as a dashed rectangle in Figure 4(b)) Av5~6), and the midpoint of the tolerance range Av5.5 is on the smaller diameter side than the limit value (Av5). In Figure 4(b), the fact that the second aperture value is maintained at the smaller diameter limit value Av5 is indicated by a black triangle (▼).

[0053] Figure 4(c) illustrates the first and second aperture values ​​when the brightness of the subject is even darker than in Figure 4(b).

[0054] In the state shown in Figure 4(c), the first aperture value (Av value) has been changed to the open side compared to the state shown in Figure 4(b), and the first aperture value is Av4.8. Since the first aperture value (Av value) has been changed to the open side, the allowable range of the second aperture value based on the first aperture value (shown by the dashed rectangle) also moves to the open side. The body-side control unit 230 changes the second aperture value (Av value) to the open side if the second aperture value (Av value) in Figures 4(a) and 4(b), which is maintained at the small diameter limit value Av5 shown by the dotted triangle, falls outside the allowable range of the second aperture value based on the first aperture value calculated this time (shown by the dashed rectangle in Figure 4(c)) Av3.8~4.8. In the state shown in Figure 4(c), the second aperture value (Av value) is determined to be Av4.3 (the solid triangle in Figure 4(c)), which is the midpoint of the acceptable range (Av3.8~4.8) for the second aperture value based on the first aperture value Av5 calculated this time.

[0055] Figure 4(d) illustrates the first and second aperture values ​​when the brightness of the subject is even darker than in Figure 4(c).

[0056] In the state shown in Figure 4(d), the first aperture value (Av value) is changed to Av4.5, which is further towards the open side than in the state shown in Figure 4(c). The allowable range of the second aperture value based on the first aperture value (shown by the dashed rectangle) also moves towards the open side. The body-side control unit 230 maintains the second aperture value Av4.3 in Figure 4(c), which was determined in the previous calculation, without changing it, because the second aperture value Av4.3 determined in Figure 4(c) is included in the allowable range of the second aperture value based on the first aperture value calculated this time (shown by the dashed rectangle in Figure 4(d)) Av3.5~4.5. By maintaining the second aperture value (Av value), the frequency of driving the aperture 362 in live view mode can be reduced.

[0057] Figure 5(a) illustrates the first and second aperture values ​​when the brightness of the subject is even darker than in Figure 4(d).

[0058] In the state shown in Figure 5(a), the first aperture value (Av value) is changed to the widest setting compared to the state shown in Figure 4(b), and the first aperture value is Av2.5. If the current second aperture value (Av4.3, shown as a dashed triangle in Figure 5(a)) is greater than the calculated first aperture value (Av2.5 in Figure 5(a)), the body-side control unit 230 sets the second aperture value to be smaller than the first aperture value without comparing the current second aperture value (Av value) with the allowable range of the second aperture value based on the first aperture value. As mentioned above, the control unit 230 calculates the amount of defocus based on the pixel signal for focus detection of the live view image, and sets the second aperture value to an aperture value that results in a shallower depth of field of the subject image than the first aperture value set for shooting. Therefore, since the newly calculated first aperture value Av2.5 is located on the wider side than the maintained second aperture value Av4.3, the midpoint value (Av2) of the allowable range of the second aperture value (Av1.5~2.5) based on the newly calculated first aperture value is determined as the second aperture value (Av value).

[0059] Figure 5(b) illustrates the first and second aperture values ​​when the brightness of the subject is even darker than in Figure 5(a).

[0060] In the state shown in Figure 5(b), the first aperture value (Av value) is changed to the open side compared to the state shown in Figure 5(a), and the first aperture value is Av2.2. Accordingly, the allowable range of the second aperture value based on the first aperture value (shown as a dashed rectangle) also moves to the open side. The body-side control unit 230 maintains the second aperture value Av2 in Figure 5(a), which was determined in the previous calculation, without changing it, because the second aperture value Av2 in Figure 5(a), which was determined in the previous calculation, falls within the allowable range of Av1.2 to 2.2 (shown as a dashed rectangle in Figure 5(b)) based on the first aperture value calculated this time. By maintaining the second aperture value (Av value), the frequency of driving the aperture 362 in live view mode can be reduced.

[0061] Figure 5(c) illustrates the first and second aperture values ​​when the brightness of the subject is even darker than in Figure 5(b). In the state of Figure 5(c), the first aperture value (Av value) is changed to the wider Av2 compared to the state of Figure 5(b), and the virtual range (shown by the dashed rectangle) also moves towards the wider Av1-2.

[0062] In this embodiment, the upper limit of the aperture 362's maximum aperture is assumed to be Av2. That is, the maximum aperture value of the interchangeable lens 3 is Av2 (F value is 2). The body-side control unit 230 maintains the first aperture value (Av value), calculated based on the Bv value and the program diagram information stored in the memory unit 235, at the maximum aperture value if it is wider than the upper limit of the maximum aperture. Also, if the first aperture value (Av value) is set to the maximum aperture value, the second aperture value (Av value) is also set to the same maximum aperture value as the first aperture value (Av value). In Figure 5(c), the black triangle (▼) indicates the maximum aperture value.

[0063] As explained above, in this embodiment, in order to reduce the frequency of driving the aperture 362 in live view mode, the second aperture value, which is the aperture value for live view, is always set to be wider than the first aperture value, which is the aperture value for shooting, and the second aperture value (Av value) is controlled to be changed as little as possible even when the brightness of the subject changes.

[0064] <Explanation of the flowchart> An example of the processing performed by the body-side control unit 230 when the live view mode described above is either the first or second live view mode will be explained with reference to the flowchart in Figure 6. The body-side control unit 230 is activated, for example, when the main switch is turned on, or it enters sleep mode if there is no operation for a predetermined period of time. When this sleep mode is canceled by operation of the operating member 280, it starts the processing shown in the flowchart in Figure 6. The cancellation of the sleep mode (return to the normal state) is performed when a switch or the like that which constitutes the operating member 280 is operated. The operation may be, for example, a half-press operation of the release button. Figure 6 explains the process of displaying the live view when the power is turned on or the sleep mode is canceled, but the live view display is repeated until the release button is fully pressed.

[0065] In step S10, the body-side control unit 230 controls the exposure setting in live view mode to a predetermined value (initial value) and performs accumulation control on the image sensor 260. For example, it instructs the interchangeable lens 3 to drive the aperture 362 to a predetermined initial value (corresponding to the second aperture value above), and controls the accumulation time and sensitivity of the image sensor 260 for live view imaging to predetermined initial values, causing the accumulation operation to take the first live view image.

[0066] In step S20, the body-side control unit 230 reads a signal from the image sensor 260 to the signal processing unit 270 and proceeds to step S30. In step S30, the body-side control unit 230 calculates the first aperture value (shooting aperture value) and the second aperture value (live view aperture value) as described above by performing an exposure calculation. That is, the body-side control unit 230 detects the brightness information (Bv value) of the subject based on the image capture pixel signal input to the signal processing unit 270, and determines the shooting aperture value (first aperture value, Av value), shutter speed (Tv value), and sensitivity (Sv value) based on the Bv value and the program diagram information stored in the storage unit 235. Furthermore, the body-side control unit 230 calculates the tolerance range for the second aperture value separately from the first aperture value. Each control value, including the calculated tolerance ranges for the first and second aperture values, is stored in the storage unit 235.

[0067] Furthermore, in step S30, the body-side control unit 230 also calculates the amount of defocus. The body-side control unit 230 instructs the signal processing unit 270 to calculate the amount of defocus using the signal output from the focus detection pixel of the image sensor 260, as described above. In this embodiment, the amount of defocus is calculated in step S30, but the focusing lens is not driven at this point.

[0068] In step S40, the body-side control unit 230 sets the aperture to 362 as the second aperture value (aperture value for live view) as explained with reference to Figures 3-5, and then performs live view display. The body-side control unit 230 instructs the signal processing unit 270 to generate a live view image using the imaging pixel signals output from the image sensor 260, and displays the generated live view image on the display unit 290.

[0069] In step S50, the body-side control unit 230 determines whether the release button has been half-pressed. If the release button has been half-pressed, the body-side control unit 230 affirms step S50 and proceeds to step S60; otherwise, it returns to step S10.

[0070] In step S60, the body-side control unit 230 moves the focusing lens constituting the lens 361 along the direction of the optical axis O relative to the interchangeable lens 3, based on the defocus amount calculated in step S30 by the signal processing unit 270. That is, the lens-side control unit 330 issues a driving instruction to the lens drive unit 370 to perform the focusing drive operation. The process then proceeds to step S70.

[0071] In step S70, the body-side control unit 230 determines whether the release button has been fully pressed. If the release button has been fully pressed, the body-side control unit 230 affirms step S70 and proceeds to step S80; otherwise, it negates step S70 and returns to step S10.

[0072] The body-side control unit 230, having returned to step S10, performs the processing from step S10 onward again. For the exposure settings from the second frame onward in live view mode, the second aperture value stored in the memory unit 235, along with the shutter speed (Tv value) and sensitivity (Sv value) stored in the memory unit 235, are used. Here, at least one of the shutter speed (Tv value) and sensitivity (Sv value) stored in the memory unit 235 may be corrected. The reason for this is that, as described above, the brightness of the live view image displayed on the display unit 290 may change due to changes in the brightness of the subject, so the brightness of the displayed live view image is adjusted by correcting the shutter speed (Tv value) and sensitivity (Sv value).

[0073] In step S80, which proceeds when the release button is fully pressed (a positive determination of step S70), the body-side control unit 230 performs an accumulation operation to capture an image for recording. At that time, the aperture 362 stored in the memory unit 235 is set as the first aperture value (aperture value for shooting, Av value), and the accumulation control of the image sensor 260 is performed using the shutter speed (Tv value) calculated by apex calculation and stored in the memory unit 235, and the sensitivity (Sv value) processing, also calculated by apex calculation and stored in the memory unit 235, is performed.

[0074] In step S90, the body-side control unit 230 reads a signal from the image sensor 260 to the signal processing unit 270 and proceeds to step S100. In step S100, the body-side control unit 230 instructs the signal processing unit 270 to perform predetermined image processing on the imaging pixel signal output from the image sensor 260 to generate an image for recording. As a result, the signal processing unit 270 performs predetermined image processing to generate an image for recording.

[0075] In step S110, the body-side control unit 230 displays the image. Specifically, the body-side control unit 230 displays the image processed by the signal processing unit 270 in step S100 on the display unit 290. In step S120, the body-side control unit 230 causes the image file processed by the signal processing unit 270 to be recorded in the recording unit 100.

[0076] In step S130, the body-side control unit 230 determines whether the live view mode has ended. If the live view mode has ended, the body-side control unit 230 affirms step S130 and terminates the process shown in Figure 6. If the live view mode has not ended, the body-side control unit 230 negates step S130 and returns to step S10. Here, "end of live view mode" means that the device is powered off, a menu is displayed on the display unit 290 by user operation, or the device enters sleep mode, or there is no longer a need to display live view.

[0077] Note that the display process (S100) and the recording process (S110) in Figure 6 may be performed in a different order, or they may be performed in parallel. In this embodiment, the defocus amount is calculated in step S30, and after the half-press operation is performed in step S50, the focusing lens is driven in step S60. However, the defocus amount may be calculated and the focusing lens driven in step S30.

[0078] In either of the first or second live view modes of the above-described embodiment, the following effects and advantages can be obtained. (1) The camera system (camera system 1), which consists of a camera body 2 and an interchangeable lens 3 equipped with an aperture 362, includes a body-side control unit 230 that calculates a first aperture value, which is the aperture value for shooting, based on the metering value, and a body-side control unit 230 that sets a second aperture value, which is the aperture value for live view, within the aperture value tolerance range based on the first aperture value. With this configuration, even if the brightness of the subject changes and the first aperture value changes, as long as the second aperture value is set within the aperture value tolerance range, the set second aperture value will be maintained without immediately changing in conjunction with the changed first aperture value. This suppresses the frequent driving of the aperture 362 in live view mode, and reduces the driving noise. In addition, because the frequency of aperture changes is reduced, the durability of the lens aperture mechanism can be improved (durability wear can be reduced). Suppressing the driving of the aperture 362 in live view mode is also preferable in that it suppresses the screen flicker of the display unit 290 that displays the live view image. Furthermore, it is also preferable in that it avoids the hunting phenomenon during metering that occurs when the aperture 362 is repeatedly driven.

[0079] (2) Since the aperture value tolerance range of the second aperture value described above is set based on the first aperture value, the aperture value limit range can be set within an appropriate range corresponding to the brightness of the subject.

[0080] (3) The aperture value tolerance range for the second aperture value (aperture value for live view) is always set to be wider than the first aperture value (aperture value for shooting). Generally, the larger the aperture diameter of aperture 362 (larger diameter side), the shallower the depth of field of the subject image becomes, as described above, and the accuracy of detecting the amount of image shift (phase difference) improves. In this embodiment, by setting the aperture value limit range to be wider than the first aperture value (wider side), it is possible to suppress a decrease in the accuracy of phase difference detection and, consequently, the accuracy of focus detection.

[0081] (4) When the brightness of the subject changes and the first aperture value is updated (newly calculated), the body-side control unit 230 updates the aperture value tolerance range of the second aperture value. Also, if the set (previously calculated) second aperture value is within the updated aperture limit range, the body-side control unit 230 does not change the second aperture value. With this configuration, the frequency of driving the aperture 362 in live view mode can be reduced.

[0082] (5) If the brightness of the subject changes and the newly calculated first aperture value (aperture value for shooting) is wider than the second aperture value set by the previous calculation result, the body-side control unit 230 sets the second aperture value (aperture value for live view) to be wider than the calculated first aperture value. Then it updates the aperture tolerance range of the second aperture value and resets (updates) the second aperture value within the updated aperture limit range. With this configuration, the aperture value limit range can be set to be wider than the first aperture value, and the driving of the aperture 362 in live view mode can be suppressed without reducing the accuracy of focus detection.

[0083] (6) The aperture value tolerance range for the second aperture value (aperture value for live view) is set to be wider than the first aperture value (in this embodiment, one stop wider than the first aperture value). The body-side control unit 230 then sets the newly set second aperture value to approximately the center of the aperture value tolerance range. Therefore, in this embodiment, the second aperture value does not need to be reset (updated) unless the brightness information of the subject increases or decreases by 0.5 stops or more in the apex value. With this configuration, the frequency of driving the aperture 362 can be appropriately reduced.

[0084] (7) The body-side control unit 230 is configured to change the upper and lower limits of the aperture value tolerance range of the second aperture value based on the information from the interchangeable lens 3. With this configuration, for example, an appropriate value can be set to match the optical characteristics of the lens 361.

[0085] (8) The information of the interchangeable lens 3 is at least one of the error tolerance based on the difference in optical characteristics between the first aperture value and the second aperture value, the shooting distance, and the magnification. With this configuration, the upper and lower limits of the aperture value limit range can be appropriately set.

[0086] (9) The camera body 2 of the camera system 1 is equipped with a body-side control unit 230 that calculates a first aperture value (aperture value for shooting) and a second aperture value (aperture value for live view), and instructs the interchangeable lens 3 to drive the aperture 362 to the second aperture value. With this configuration, the camera body 2 can perform calculations on its side and send an instruction to the interchangeable lens 3 to drive the aperture 362 to the second aperture value. (10) The body-side control unit 230 may change the aperture value tolerance range of the second aperture value depending on the autofocus mode (for example, a mode in which the focus position is fixed while the shutter button is half-pressed after focusing once, or a mode in which the focusing operation is repeatedly performed while the shutter button is half-pressed). In manual mode as well, aperture control may be performed within the aperture value tolerance range of the second aperture value.

[0087] The following modifications are also within the scope of the present invention, and it is possible to combine one or more of these modifications with the embodiments described above. (Modification 1) The processing performed by the camera system (camera system 1) of the above-described embodiment may be appropriately divided between the body-side control unit 230 on the camera body 2 side and the lens-side control unit 330 on the interchangeable lens 3 side. For example, the camera body may calculate a first aperture value and a second aperture value, and transmit the driving force to drive the aperture 362 on the interchangeable lens from the camera body to the interchangeable lens. That is, the camera body 2A includes a body-side control unit 230 that calculates the first aperture value and the second aperture value, an actuator that generates power for the aperture 362 drive mechanism on the interchangeable lens 3A to drive the aperture 362 to the second aperture value, and a transmission member that transmits power to the interchangeable lens 3A. By configuring it in this way, the driving of the aperture 362 in live view mode can be suppressed in the camera system.

[0088] (Modification 2) Alternatively, the camera body may calculate a first aperture value and a second aperture value, and transmit the second aperture value from the camera body to the interchangeable lens. When the interchangeable lens receives the second aperture value, the aperture drive unit 380 drives the aperture 362 to the second aperture value. That is, the interchangeable lens 3B includes a lens-side communication unit 340 that receives the second aperture value set by the body-side control unit 230 of the camera body 2, an aperture drive unit 380 that drives the aperture 362, and a lens-side control unit 330 that instructs the aperture drive unit 380 to drive the aperture 362 to the second aperture value received by the lens-side communication unit 340. By configuring it in this way, the frequency of driving the aperture 362 in live view mode can be appropriately suppressed in the camera system.

[0089] In the above example, the lens control unit 330 controls the aperture 362 using an aperture value (Av value) based on apex calculation. However, the lens control unit 330 may also control the aperture value using the number of stops down from the widest aperture of the interchangeable lens 3.

[0090] (Modification 3) In the camera system (camera system 1) of the above-described embodiment, the body-side control unit 230 of the camera body 2 calculates two aperture values, a first aperture value and a second aperture value, and transmits these two aperture values ​​to the lens-side control unit 330 of the interchangeable lens 3 via the communication unit. However, the system is not limited to this configuration; the body-side control unit 230 may calculate only the first aperture value and transmit only the first aperture value to the lens-side control unit 330 via the communication unit. In that case, the lens-side control unit 330 autonomously sets the second aperture value. That is, the lens-side control unit 330 of the interchangeable lens 3 sets the second aperture value, which is the aperture value for live view, within the aperture value tolerance range based on the first aperture value received from the camera body 2. Similar to the embodiment described above, the aperture value tolerance range for the second aperture value (aperture value for live view) set by the lens-side control unit 330 is always wider than the first aperture value (aperture value for shooting). The lens-side control unit 330 of the interchangeable lens 3 compares the first aperture value transmitted from the camera body 2 with the currently set second aperture value. Similar to the embodiment described above, even if the first aperture value received from the camera body 2 changes, the lens-side control unit 330 is configured to maintain the set second aperture value without immediately changing in conjunction with the received first aperture value, as long as the second aperture value is set within the aperture value tolerance range. Similar to the embodiment described above, the lens-side control unit 330 of the interchangeable lens 3 sets the aperture value tolerance range of the second aperture value (aperture value for live view) to one stop wider than the first aperture value (aperture value for shooting), and sets the newly set second aperture value to approximately the center of the aperture value tolerance range. As long as the brightness information of the subject does not increase or decrease by 0.5 stops or more in apex value, the second aperture value does not need to be reset (updated). With this configuration, the frequency of driving the aperture 362 can be appropriately reduced. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0091] The disclosures of the following priority application are incorporated herein by reference. Japanese Patent Application No. 2018-135197 (filed July 18, 2018) [Explanation of Symbols]

[0092] 1...Camera system, 2...Camera body, 3...Interchangeable lens, 230...Body-side control unit, 235...Memory unit, 240...Body-side communication unit, 270...Signal processing unit, 290...Display unit, 330...Lens-side control unit, 340...Lens-side communication unit, 350...Lens-side memory unit, 360...Shooting lens, 362...Aperture, 370...Lens drive unit, 380...Aperture drive unit

Claims

[Claim 1] An image sensor that captures an image of a subject formed by an optical system with an aperture and outputs a signal, A display unit that displays an image generated based on the aforementioned signal, An operating unit that instructs the image sensor to take an image through operation, A calculation unit calculates a first aperture value, which is the aperture value for shooting based on the operation of the control unit, based on the aforementioned signal. A control unit that sets the first aperture value and a second aperture value which is the aperture value for shooting a through-image display that displays the image based on the signal repeatedly captured by the image sensor on the display unit, Equipped with, When the first aperture value is changed in accordance with a change in the brightness of the subject, the control unit does not change the second aperture value if the second aperture value is within the allowable range based on the changed first aperture value. Imaging device.

Images