JP2012039178A - Imaging apparatus, exposure control method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress image quality degradation due to the change of an aperture value accompanying view angle variation when picking up moving images.SOLUTION: A lens information acquisition part 41 stores information on an open F value acquired from a photographing lens 11 mounted on an apparatus body in a memory 52, and a system control circuit 50 acquires the information on the open F value from the memory 52 as the one of the photographing lens 11 at present. When the photographing lens 11 is a lens of a different open F value depending on a view angle from the acquired open F value, the system control circuit 50 generates a dark side setting program diagram for setting an aperture value AV with the darkest open F value among the variable open F values as the limit aperture value of a bright side, sets an AV value, a TV value and an ISO value on the basis of object luminance EV using the diagram, and executes exposure control.

Description

  The present invention relates to a technique for controlling exposure in moving image capturing.

  2. Description of the Related Art Conventionally, electronic viewfinders are often used in imaging devices such as digital cameras. Specifically, the light passing through the photographing lens is received by an image pickup device such as a CCD used for photographing, and the photoelectrically converted image signal is sequentially displayed on an image display device such as an LCD.

  In recent imaging apparatuses, the imaging element is used for various purposes other than the still image shooting use and the viewfinder use. That is, it is also used for AF (Auto Focus Control) for automatically focusing on a subject and for AE (Auto Exposure Control) for appropriately controlling the brightness of a subject. During AF and AE, the image sensor is used as a distance measuring sensor and a photometric sensor, respectively. As described above, the image sensor may allow the user to monitor the subject image as a finder and may also perform shooting preparation work such as AF and AE in parallel.

  The camera is provided with a diaphragm for adjusting the amount of incident light and a shutter for adjusting the exposure time as factors for determining exposure. In the case of a digital camera, there is also gain control for amplifying / attenuating a signal level read from the image sensor after receiving light by the image sensor. In particular, the aperture mechanism must not only change the exposure but also consider that the depth of field changes depending on the aperture diameter. As the aperture diameter increases, the depth of field decreases, and as the aperture diameter decreases, the depth of field increases. Taking this optical phenomenon into consideration, the aperture is set close to the open position during AF, and focusing is performed in a state where the depth is shallower than when shooting still images. It is known that it can be prevented.

  In cameras equipped with AF and AE functions, a release button for a user to instruct photographing is generally configured in two stages. That is, AF and AE are performed by pressing the button shallowly to perform focusing and exposure adjustment for still image shooting, and shooting is started by pressing the button deeply. Hereinafter, in such a two-stage configuration, pressing the release button shallowly is referred to as SW1 operation, and pressing deeply is referred to as SW2 operation.

  When AF is performed in the SW1 operation, the aperture is controlled close to the open position as described above. After the AF is completed, the aperture diameter used for still image shooting is controlled in advance, so that it is not necessary to drive the aperture after the SW2 is pressed, which is effective in reducing the release time lag. As described above, since the diaphragm is a mechanical mechanism, it is premised that driving takes a certain amount of time, and a proposal has been made in consideration thereof (see Patent Document 1 below).

  Furthermore, since the aperture control takes a certain amount of time, as described above, when the user drives the aperture while the subject image is being monitored as a finder application, a deteriorated image while the aperture is moving is displayed on the image display device. There was a problem of being output. In order to prevent this, an image display device is not updated during aperture driving, and an image before the aperture driving is displayed (see Patent Document 2 below). However, this proposed apparatus is not suitable for use as a finder that captures the movement of a subject because the image update seems to have stopped temporarily.

  In addition, there has been a proposal that the aperture is not moved depending on conditions so that image quality degradation when controlling the aperture is not shown in the viewfinder or recorded in a moving image (see Patent Document 3 below). However, in this proposed apparatus, there is a problem that the tracking range to the subject brightness is narrowed by not moving the aperture, and the AE performance is deteriorated.

  Further, a proposal has been made to correct the charge accumulation time that overlaps the aperture driving time so as to suppress the fluctuation of the charge accumulation amount in the charge accumulation of the image pickup element that is sequentially performed. (See Patent Document 4 below). However, in this proposed apparatus, in a system in which lenses can be exchanged, it is impossible to control at an optimum driving timing for each lens, and it is difficult to perform correction so as to suppress fluctuations in the amount of accumulated charge.

Japanese Patent No. 03817563 JP 2006-352905 A Japanese Patent Laid-Open No. 11-112865 JP 2008-271812 A

  As described above, the image pickup device for still image shooting is used for various single uses or compound uses such as viewfinder, AF, AE, movie shooting, etc., and the diaphragm is driven according to the requirements for each use. As a result, a good captured image with good response can be obtained. However, while the camera user is capturing a subject image for use in a viewfinder or video recording, image quality degradation may occur due to aperture drive, which greatly impairs the performance of the electronic viewfinder and video recording image quality. There was a problem.

  Specifically, a description will be given below of a problem in a case where a lens having a different open F value is mounted for each angle of view in an imaging device capable of exchanging lenses.

  FIG. 4 shows an example of a program diagram for exposure control during general moving image capturing. The aperture value can be set up to the open F value according to the angle of view. In FIG. 4, the horizontal axis on the upper side and the vertical axis on the left side indicate the subject brightness EV, and the lower horizontal axis indicates the charge accumulation time TV and ISO sensitivity (Gain: gain for amplifying the signal level). The right vertical axis indicates the aperture value AV of the aperture. The larger the EV value, the more right diagonal lines in FIG. The aperture value AV is on the small aperture side (the direction in which the incident light amount decreases) toward the upper side, and on the open side (the direction in which the incident light amount increases) toward the lower side.

  The charge accumulation time TV corresponds to the shutter speed, and is shorter toward the right side of the figure. The reciprocal of the value of the charge accumulation time TV is the shutter speed (1/60 seconds for 60, 1/30 seconds for 30). Hereinafter, the reciprocal number is mainly used. In the region where the charge accumulation time TV is shorter than 1/30 seconds (the numerical value is larger than 30), the ISO value is 100 and constant. In moving image capturing with a frame rate of 30 FPS (frames / second), a shutter speed longer than 1/30 seconds cannot be used as a TV value, so the slowest speed is set to 1/30 seconds. Therefore, on the left side, the shutter speed is constant at 1/30 seconds, and only the ISO value increases. The numerical value of the ISO value in the figure is a multiplier with respect to the ISO value 100. For example, x2 and x4 mean ISO values = 200 and 400. On the lower horizontal axis, since either the TV value or the ISO value changes, it is described as “TV value / ISO value”.

  With reference to the program diagram, the AV value, the TV value, and the ISO value are obtained from the intersection of the diagonal line of the EV value and the diagram. Further, when hysteresis is provided and the EV value decreases, the AV value, the TV value, and the ISO value are obtained from the intersection with the line indicated by the dotted line.

  Here, for example, a lens having a different open F value for each angle of view (focal length) = a lens having an angle of view (focal length) of “18-200 mm” and an open F value of “F3.5-5.6”. Assume that it is installed. Then, in a dark scene such as night, consider a situation of moving image shooting in which the angle of view, that is, the zoom focal length is moved from 18 mm to 200 mm and the face is gradually raised.

  The open F value is 3.5 at an angle of view of 18 mm, the open F value is 4.5 at an angle of view of 100 mm, and the open F value is 5.6 at an angle of view of 200 mm. The limit aperture value that can be set on the bright side according to the angle of view is the open F value. Therefore, in exposure control, the program diagrams shown in FIGS. 5A, 5B, and 5C are actually generated and used corresponding to the angle of view of 18 mm, 100 mm, and 200 mm.

  In FIG. 4, horizontal straight lines L1, L2, and L3, which are part of the program diagram, are straight lines drawn on the aperture value AV set to the open F value corresponding to the angle of view of 18 mm, 100 mm, and 200 mm, respectively. is there. FIGS. 5A, 5B, and 5C show program diagrams having straight lines L1, L2, and L3 separately. In the range where the EV value is smaller than EV9, the wide aperture at each angle of view is used. However, in the range where the EV value is larger than EV9, if the camera shake is not taken into consideration, all program diagrams are common. Although only three straight lines L1, L2, and L3 are illustrated here, the open F value changes in a stage with more than 3 (for example, 12 stages) in the range of the angle of view of 18 mm to 200 mm.

  Here, for example, when the subject brightness EV is EV3 and the zoom ring is moved from an angle of view of 18 mm to 200 mm, an open F value is used at each angle of view, and an aperture value of F3.5 to Changes to F5.6. Accordingly, the ISO value or TV value also changes. That is, as shown in FIG. 4, the intersections of the EV3 diagonal line and the diagram are the intersections P1, P2, and P3 for the angle of view of 18 mm (straight line L1), 100 mm (straight line L2), and 200 mm (straight line L3), respectively. is there. Therefore, at an angle of view of 18 mm, the aperture value AV = 3.5, the TV value = 1/30, and the ISO value = 2400 (see FIG. 2A). At an angle of view of 100 mm, the aperture value AV = 4.5, the TV value = 1/30, and the ISO value = 4800 (see FIG. 2B). At an angle of view of 200 mm, the aperture value AV = 5.6, the TV value = 1/30, and the ISO value = 6400 (see FIG. 2C).

  Thus, the ISO value changes as the aperture value AV changes. However, the amount of noise change at the time of high ISO is significant, and the image quality of the image in FIG. 2C is more severely deteriorated than in FIG. That is, when lenses having different open F values depending on the angle of view are used, there is a problem that the amount of noise varies with the angle of view and the image quality is not stable.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to suppress image quality deterioration caused by a change in aperture value accompanying a change in the angle of view when capturing a moving image.

  In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus capable of capturing a moving image, an acquisition unit that acquires information on an open F value of a lens attached to the apparatus body of the imaging apparatus, and an imaging element Calculating means for calculating subject luminance from the image information obtained by the above, an aperture value for adjusting the amount of light incident on the image sensor based on the subject brightness calculated by the calculation means, charge accumulation time of the image sensor and ISO Control means for controlling exposure by setting a value, and the control means is acquired by the acquisition means when a lens having an open F value that varies depending on the angle of view is attached when capturing a moving image. With reference to the information on the open F value, control is performed so that the darkest open F value among the open F values that can be changed is set as the limit aperture value on the bright side, and the aperture value is set.

  According to the present invention, it is possible to suppress deterioration in image quality due to a change in aperture value accompanying a change in angle of view when capturing a moving image.

1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment of the present invention. It is a figure which shows the example of exposure control according to an angle of view. It is a figure which shows a lens information table. It is a program diagram for exposure control at the time of moving image capturing. It is a generated program diagram. It is another example of the generated program diagram. It is a flowchart of a moving image recording preparation process. It is a flowchart of a moving image recording process. It is a flowchart of the moving image recording process in 2nd Embodiment. It is a flowchart of the determination process of image freeze. It is a flowchart of a pattern recognition process. FIG. 7 is an explanatory diagram of pattern recognition processing (FIG. (A)), and is a diagram (FIGS. (B) and (c)) showing an example of a statistical relationship between the face size indicated by the number of pixels on the image and the eye spacing. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the imaging apparatus according to the first embodiment of the present invention. The imaging apparatus is configured as a digital camera that can capture moving images. In particular, a digital camera capable of exchanging lenses, such as a digital single lens reflex camera, is used.

  In FIG. 1, reference numeral 100 denotes an image processing apparatus, which is also an apparatus main body of the imaging apparatus. The image processing apparatus 100 includes a photographing lens 11, an exposure control mechanism 12 including an aperture and a shutter, an image sensor 14 such as a CCD that converts an optical image into an electric signal, and an analog signal output from the image sensor 14 that is converted into a digital signal. A D converter 16 is provided.

  The system control circuit 50 controls the entire image processing apparatus 100, and functions as a control unit, an acquisition unit, an update unit, a calculation unit, a grasping unit, a determination unit, and a calculation unit in processing to be described later.

  In the image processing apparatus 100, the timing generation circuit 18 is controlled by the memory control circuit 22 and the system control circuit 50, and clock signals and control signals are sent to the image sensor 14, the A / D converter 16, and the D / A converter 26. Supply. The image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22.

  In the image processing circuit 20, predetermined calculation processing is performed using the captured image data, and the system control circuit 50 applies to the exposure control circuit 40 and the distance measurement control circuit 42 based on the obtained calculation result. Control. That is, the system control circuit 50 performs a TTL (through-the-lens) AF (autofocus) process, an AE (automatic exposure) process, and an EF (flash pre-emission) process. Further, the image processing circuit 20 performs predetermined arithmetic processing using captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result. The system control circuit 50 controls the image processing circuit 20 to calculate the subject brightness EV from the image information obtained from the image sensor 14.

  The face detection unit 58 performs a predetermined face detection process on the data from the image processing circuit 20 or the data from the memory control circuit 22. The face detection unit 58 detects whether or not a face exists in the image, and many methods have already been realized as face recognition techniques. For example, there are a method of extracting a human face based on skin color data of a photographed image, a method of extracting a face candidate area corresponding to the shape of the human face, and determining a face area from the feature amount in the area. In this embodiment, any method may be adopted as the face detection method.

  The memory control circuit 22 includes an A / D converter 16, a timing generation circuit 18, an image processing circuit 20, an image display memory 24, a D / A converter 26, a memory 30, a compression / decompression circuit 32, and a movement amount detection unit 59. Control. The data of the A / D converter 16 is sent to the image display memory 24 or the memory 30 directly via the image processing circuit 20 and the memory control circuit 22 or the data of the A / D converter 16 is directly sent to the image display memory 24 or the memory 30 via the memory control circuit 22. Written. The image display unit 28 is a display device composed of a TFT-LCD or the like, and the display image data written in the image display memory 24 is displayed on the image display unit 28 via the D / A converter 26. An electronic viewfinder function can be realized by sequentially displaying captured image data using the image display unit 28.

  The memory 30 is a memory serving as a storage unit for storing captured still images and moving images, and has a sufficient storage capacity for storing a large number of still images and long-time moving images. Even in the case of continuous shooting or panoramic shooting in which a plurality of still images are continuously shot, it is possible to write a large amount of images to the memory 30 at high speed. The memory 30 can also be used as a work area for the system control circuit 50.

  The compression / decompression circuit 32 compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like, reads an image stored in the memory 30, performs compression processing or decompression processing, and stores the processed data in the memory 30. Write. The exposure control circuit 40 controls the exposure control mechanism 12 including an aperture and a shutter. The exposure control circuit 40 also has a flash light control function in cooperation with the flash 48. The distance measurement control circuit 42 controls focusing of the photographing lens 11, and the zoom control circuit 44 controls zooming of the photographing lens 11.

  An optical viewfinder 104 is provided in the apparatus main body, and an image to be taken can be confirmed using only the optical viewfinder 104 without using the electronic viewfinder function of the image display unit 28.

  The flash 48 has an AF auxiliary light projecting function and a flash light control function. The exposure control circuit 40 and the distance measurement control circuit 42 are controlled using the TTL method. Based on the captured image data and the calculation result calculated by the image processing circuit 20, the system control circuit 50 controls the exposure control circuit 40 and the distance measurement control circuit 42.

  The nonvolatile memory 56 is an electrically erasable / recordable memory, and for example, an EEPROM or the like is used. The memory 52 is a memory that functions as a storage unit that stores constants, variables, programs, and the like for operation of the system control circuit 50.

  The lens information acquisition unit 41 acquires the lens ID of the photographic lens 11 attached to the apparatus main body and stores it in the memory 52 under the control of the system control circuit 50. A lens information table as shown in FIG. 3 is stored in the nonvolatile memory 56 in advance. The lens information table shown in FIG. 3 is a table in which the focal length and the open F value at the wide end and the tele end are associated with the lens ID. By referring to this table, if the lens ID is known, it can be understood how the open F value can be converted depending on the angle of view. Then, the lens information acquisition unit 41 acquires information on the focal length and the open F value for each angle of view corresponding to the acquired lens ID from the lens information table (FIG. 3) and stores the information in the memory 52.

  The lens information acquisition unit 41 can also acquire the information of the open F value directly from the mounted photographing lens 11 even when the lens ID cannot be acquired. Information on the open F value is also stored in the memory 52. The lens information acquisition unit 41 acquires lens ID or open F value information every time a photographic lens 11 is newly attached to the apparatus main body, and stores the latest open F value information in the memory 52. When the lens ID is acquired, information on the open F value obtained by referring to the lens information table (FIG. 3) is stored. Therefore, the content of the open F value information stored and held in the memory 52 is always updated to that of the photographic lens 11 currently mounted. When the photographic lens 11 is once attached and the lens is not exchanged thereafter, the lens information acquisition unit 41 stores the current open F value information of the photographic lens 11 in the memory 52 instead of acquiring the information from the photographic lens 11. Get from the information that is.

  The open F value determination unit 45 determines whether the open F value for each angle of view is different based on the lens information obtained by the lens information acquisition unit 41 according to the control by the system control circuit 50. The diaphragm drive determination unit 49 determines whether the exposure control circuit 40 is currently performing aperture drive. The view angle variation calculation unit 43 calculates the view angle variation between frames based on the lens information obtained by the zoom control circuit 44 and the lens information acquisition unit 41. These determinations and calculations are both performed according to control by the system control circuit 50.

  The program diagram generation unit 47 generates a program diagram corresponding to a change in the photographic lens 11 to be mounted or a scene mode in accordance with the control of the system control circuit 50. The movement amount detection unit 59 calculates the movement amount of the subject based on the information obtained by the face detection unit 58. The image update determination unit 55 determines the movement amount of the subject calculated by the movement amount detection unit 59, the field angle variation amount between frames calculated by the field angle variation calculation unit 43, and the aperture variation amount by the exposure control circuit 40. In response, it is determined whether or not to update the display image (FIG. 10).

  The display unit 54 is configured by, for example, a combination of an LCD, an LED, a sound generation element, and the like, and includes a display device and a speaker. One or a plurality of display units 54 are installed at positions that are easily visible near the operation unit 70 that functions as a receiving unit that receives an input of a threshold value of the ISO value. The display unit 54 displays an operation state, a message, and the like using characters, images, sounds, and the like according to the execution of the program in the system control circuit 50. The display unit 54 is partially installed in the optical viewfinder 104.

  Reference numerals 60, 62, 66, 68, and 70 are operation units for inputting various operation instructions of the system control circuit 50, and include one or a plurality of switches, dials, touch panels, pointing by line-of-sight detection, voice recognition devices, and the like. Consists of These operation units are specifically as follows.

  The mode dial switch 60 switches between function modes such as power-off, automatic shooting mode, shooting mode (still image shooting mode, moving image shooting mode), panoramic shooting mode, playback mode, multi-screen playback / erase mode, PC connection mode, etc. It can be set. The shutter switch 62 is turned on in the middle of operation of a shutter button (not shown) by performing a SW1 operation that is pressed lightly, and commands to start operations such as AF processing, AE processing, AWB processing, and EF processing. The shutter switch 62 is also turned on when the SW2 operation is performed by pressing it deeply to complete the operation of a shutter button (not shown), thereby instructing the start of a series of recording processing operations. In this series of recording processes, an exposure process in which a signal read from the image sensor 14 is written into the memory 30 via the A / D converter 16 and the memory control circuit 22, and the image processing circuit 20 and the memory control circuit 22 are used. Development processing using the above calculation is included. Furthermore, a recording process is included in which image data is read from the memory 30, compressed by the compression / decompression circuit 32, and the image data is written to the recording media 200 and 210.

  The image display ON / OFF switch 66 can set ON / OFF of the image display unit 28. If this function is used, it is possible to save power by cutting off the current supply to the image display unit 28 when shooting using the optical viewfinder 104. The quick review ON / OFF switch 68 sets a quick review function for automatically reproducing captured image data immediately after shooting. In the present embodiment, it is assumed that a function for setting a quick review when the image display unit 28 is turned off is provided.

  The operation unit 70 includes various buttons and a touch panel. For example, a menu button, a set button, a macro button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, a menu movement + (plus) button, and a menu movement− (minus) button. . Furthermore, it has a playback image movement + (plus) button, a playback image-(minus) button, a shooting image quality selection button, an exposure correction button, a date / time setting button, and the like.

  The power supply control unit 80 is configured by a battery detection circuit, a DC-DC converter, a switch circuit that switches blocks to be energized, and the like. The power supply control unit 80 detects the presence / absence of a battery, the type of battery, and the remaining battery level, controls the DC-DC converter based on the detection result and the instruction of the system control circuit 50, and requires the necessary voltage. It is supplied to each part including the recording medium for a period. The power supply unit 86 includes a primary battery such as an alkaline battery or a lithium battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li battery, an AC adapter, and the like, and is connected to the power control unit 80 by connecting the connector 82 and the connector 84. Connected.

  The recording media 200 and 210 are constituted by a memory card, a hard disk, or the like. The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, or the like, an interface (I / F) 204 with the image processing apparatus 100, and a connector 206 for connecting to the image processing apparatus 100. The recording medium 210 includes a recording unit 212 composed of a semiconductor memory, a magnetic disk, and the like, an interface 214 with the image processing apparatus 100, and a connector 216 that connects to the image processing apparatus 100.

  The interface 90 and the interface 94 are interfaces with recording media 200 and 210 such as a memory card and a hard disk. The connectors 92 and 96 are connectors for connecting to the recording media 200 and 210. The recording medium attachment / detachment detection unit 98 detects whether or not the recording media 200 and 210 are attached to the connectors 92 and 96, respectively.

  In this embodiment, the interface and the connector for attaching the recording medium are provided with two systems. However, these may have a single system or a plurality of systems. Moreover, it is good also as a structure provided with combining the interface and connector of a different standard.

  The communication unit 110 has various communication functions such as RS232C, USB, IEEE1394, P1284, SCSI, modem, LAN, and wireless communication. A connector (antenna) 112 is a connector that connects the image processing apparatus 100 to another device by the communication unit 110, and is an antenna in the case of wireless communication.

  Incidentally, a program diagram is stored in the nonvolatile memory 56. The stored program diagram includes not only those that are used as they are, but also those that serve as a base for generation. For example, with respect to the program diagram shown in FIG. 4 described above, which of the horizontal straight lines (L1, L2, L3, etc.) that are part of the program diagram is selected in the region where the EV value is smaller than EV9. This is determined when the program diagram is generated. Some examples of actually generated program diagrams are shown in FIGS. 5A, 5B, and 5C. The aperture value AV is an aperture value that adjusts the amount of light incident on the image sensor 14.

  FIG. 4A shows a program diagram illustrating three types of straight lines L1, L2, and L3. However, a program diagram having a straight line corresponding to each angle of view is provided individually for the same number as the open F-number variable step (for example, 12 steps) in the range where the angle of view of the photographing lens 11 is variable. It may be stored in advance in the nonvolatile memory 56. That is, each of the different program diagrams as shown in FIGS. 5A, 5B, and 5C is stored, and a process called “program diagram selection” is performed instead of “program diagram generation”. It may take a form. However, the subsequent designation is “generation” without distinction. The generated program diagram is stored in the memory 52.

  As described above, the photographic lens 11 having a different open F value for each angle of view (focal length), an angle of view of “18-200 mm”, and an open F value of “F3.5-5.6” is attached. Consider the situation of moving image shooting in which the angle of view changes from 18 mm to 200 mm. Then, a program diagram corresponding to the angle of view is generated, and the program diagrams shown in FIGS. 5A, 5B, and 5C are generated corresponding to the angle of view of 18 mm, 100 mm, and 200 mm. . Then, as described above, as the aperture value AV changes, the ISO value (ISO sensitivity) also changes, and the amount of noise change at high ISO is significant. Therefore, FIG. 2B and FIG. The deterioration in image quality is greater in FIG. 2C than in 2B.

  In the same photographing lens 11, as shown in FIGS. 2G and 2H, the open F value is 4.0 at an angle of view of 98 mm, and the open F value is 4.5 at an angle of view of 100 mm. This is because the limit aperture value that can be set on the bright side according to the angle of view is the open F value.

  Here, for example, when the subject brightness EV is EV3 and the angle of view is 98 mm, the open F value is 4.0. Therefore, the intersection of the hatched line and the diagram of EV3 is the intersection P4 shown in FIG. Therefore, at an angle of view of 98 mm, the aperture value AV = 4.0, the TV value = 1/30, and the ISO value = 3200. At an angle of view of 100 mm, the aperture value AV = 4.5, the TV value = 1/30, and the ISO value = 4800. When shooting is performed such that the angle of view is 98 mm and 100 mm, the ISO value is switched between 3200 and 4800, and the aperture value AV is switched between F4.0 and F4.5 (FIG. 2G). (See (h)). Therefore, the amount of noise and the depth of field greatly differ even if the focal length is only 2 mm.

  Therefore, in the present embodiment, when the photographing lens 11 having a different open F value depending on the angle of view is attached, the darkest open F value among the open F values that can be changed is set as the aperture value on the bright side. A program diagram in which AV is set is generated and used for exposure control. Specifically, in the case where the taking lens 11 having different open F values according to the above-described illustrated angle of view is mounted, the aperture does not change due to the change of the view angle, so that it does not depend on the respective open F values. ) Is generated. Hereinafter, such a program diagram in which the aperture value AV is set with the darkest open F value among the variable open F values as the brightest limit aperture value is also referred to as a “dark side set program diagram”. .

  According to the program diagram of FIG. 5C, in the range where the subject brightness EV is EV12 or less, the control is performed to limit the aperture opening to F5.6. That is, the limit aperture value on the bright side is set to F5.6, which is the darkest open F value among the open F values that can be changed. For example, when the subject brightness EV is EV3 and the zoom ring is moved from 18 mm to 200 mm, the open F value at the angle of view 18 mm is F3.5, the open F value at the angle of view 100 mm is F4.5, and the angle of view is 200 mm. The open F value is F5.6.

  For example, it is assumed that moving image shooting is performed while changing the angle of view at EV3, aperture value AV = F5.6, and there is no brightness fluctuation during the angle of view fluctuation. In this case, according to the program diagram of FIG. 5C, as shown in FIGS. 2D, 2E, and 2F, the aperture value AV = 5. 6. Common for TV value = 1/30 and ISO value = 6400. Therefore, the aperture value AV, TV value, and ISO value are all constant, and there is no amount of noise change between the angles of view, so that the effect of stabilizing the image quality can be obtained.

  FIG. 6 is another example of a program diagram generated in the present embodiment. In the program diagram shown in FIG. 5C, the horizontal straight line L3 is fixed at the aperture value AV = 5.6 in the region where the EV value is smaller than EV9 (the region substantially smaller than EV12). In contrast, in the program diagram of FIG. 6, the straight line L3 is fixed at the aperture value AV = 5.6 in the region where EV4 <EV value <EV12, and the aperture value AV = 3.5 in the region where EV value <EV4. It becomes the fixed straight line L13. That is, the straight line L switches at the boundary of EV value = EV4.

  Here, the user can set the upper limit setting value of the ISO value. This upper limit set value can be input by the operation unit 70 and stored in the memory 52. As the upper limit setting value of the ISO value, three types of "total aperture upper limit value", "non-open aperture upper limit value (threshold value)", and "open aperture upper limit value" can be set. When a normal program diagram other than the “dark side setting program diagram” is generated, the “overall aperture upper limit value” is reflected. When the “dark side setting program diagram” is generated, when “aperture upper limit value (threshold value) other than full aperture” and “maximum open aperture value” are set, these are reflected. However, when only the “total aperture upper limit value” is set, the “total aperture upper limit value” is reflected.

  For example, when the open F value according to the angle of view of the photographic lens 11 is constant and 6400 is set as the overall aperture upper limit value, a normal program diagram is generated. At that time, as illustrated in FIGS. 5A to 5C, the left end of the straight line L that defines the maximum ISO value is a program diagram corresponding to ISO value = 6400. The position of the AV value (vertical position) of the straight line L in these cases is set to the open F value of the photographing lens 11.

  When the photographing lens 11 having a different open F value depending on the angle of view is attached, a “dark side setting program diagram” is generated. At this time, if only the overall aperture upper limit value is set and is set to 6400, a program diagram in which the left end of the straight line L corresponds to ISO value = 6400 as illustrated in FIG. It becomes. In this case, the position of the AV value of the straight line L is set such that the brightest limit aperture value is the darkest open F value (F5.6 in this example) among variable open F values.

  Further, when the “dark side setting program diagram” is generated, it is assumed that “aperture upper limit value (threshold value) other than full open” = 3200 and “aperture open upper limit value” = 6400. In this case, the program diagram has a stepped straight line L as illustrated in FIG. In this example, the left end of the straight line L3 is defined by the upper limit value of the aperture other than the open range (ISO value = 3200), and the left end of the straight line L13 is defined by the upper limit value at the time of the open stop (ISO value = 6400). In the program diagram in which the straight line L is switched at the boundary of “aperture upper limit value other than full open” as shown in FIG. The darkest open F value is set.

  According to the example of FIG. 6, in the range of the subject luminance EV (EV4 <EV value) where the ISO value does not exceed the aperture upper limit value (here, 3200) other than full open, as in the example of FIG. The limit aperture value AV on the bright side is fixed to the darkest open F value among the open F values that can be changed. However, in the range of the subject luminance EV (EV value <EV4) where the ISO value exceeds the aperture upper limit value (threshold value) other than full aperture, the open F value corresponding to the angle of view is bright as in the example of FIG. An aperture value AV is set as the limit aperture value on the side. As a result, it is possible to shoot with an open aperture only when the brightness is less than EV4, and it is possible to shoot in such a way that the sensitivity does not become insufficient even in a dark environment.

  Next, exposure control in moving image recording will be described using the flowcharts of FIGS. FIG. 7 is a flowchart of the moving image recording preparation process. The processing in FIG. 7 is started when the shooting mode is set to the moving image shooting mode by the mode dial switch 60.

  First, the system control circuit 50 determines whether or not information on the open F value of the photographing lens 11 mounted on the apparatus main body has been acquired (step S101). That is, it is determined whether or not the open F value information is stored in the memory 52. When the information on the open F value has been acquired, the system control circuit 50 advances the process to step S103. In this case, the system control circuit 50 acquires information on the open F value stored in the memory 52 as that of the current photographing lens 11.

  When the lens is replaced, the open F value may change from that of the lens that was previously mounted. However, if information on the open F value has already been acquired, it is unnecessary by using the information. Less processing and communication. That is, as long as there is no new lens replacement, information on the open F value can be acquired from the stored contents in the memory 52, so the processing load is reduced.

  On the other hand, when the information on the open F value has not been acquired, the system control circuit 50 controls the lens information acquisition unit 41 to acquire information on the open F value corresponding to the angle of view (focal length) of the photographing lens 11. (Step S102), the process proceeds to step S103. In step S102, as described above, the lens information acquisition unit 41 acquires information on the lens ID or open F value of the photographing lens 11 attached to the apparatus main body. Further, the memory 52 stores the open F value acquired from the lens ID and the lens information table (FIG. 3) or directly acquired open F value information. Then, the system control circuit 50 acquires information on the open F value stored this time as that of the current photographing lens 11.

  In the case of a camera that cannot acquire the open F value for each angle of view, the open F value may be acquired by changing the zoom position to the wide end and the tele end, and stored in the memory 52. In order to prevent high-speed processing from being performed every time the power is turned on or when a moving image is recorded, the acquired information is stored in a storage area that does not disappear even when the power is turned on / off, and some lens information is stored. To obtain information on the open F value.

  Next, in step S103, the system control circuit 50 acquires information on the upper limit set values of the ISO value, the charge accumulation time TV, and the AV value. The upper limit setting value of the ISO value and the upper limit setting value of the TV value can be arbitrarily set by the user, and the setting values are stored in the memory 52. When these are set, the system control circuit 50 can acquire them from the memory 52. Further, the upper limit setting value of the AV value is acquired from the photographic lens 11. As described above, there are three types of ISO value upper limit setting values: the overall aperture upper limit value, the aperture upper limit value (threshold value) other than the full aperture value, and the open aperture maximum value.

  Next, in step S104, the system control circuit 50 causes the program diagram generation unit 47 to calculate from the open F value corresponding to the angle of view acquired in step S102 and the upper limit setting value of the ISO value acquired in step S103. Control to generate a program diagram. Further, the system control circuit 50 stores the generated program diagram in the memory 52.

  That is, first, when there is no change in the open F value at all angles of view, a program diagram based on the one shown in FIG. 4 (one of those illustrated in FIGS. 5A to 5C) is generated. The At this time, the position of the AV value of the straight line L is determined by the acquired open F value (constant), and the left end position of the straight line L is determined from the upper limit set value of the acquired ISO value. For example, if the open F value is F4.5 and the upper limit setting value of the ISO value is 6400, the program diagram shown in FIG. 5B is generated.

  Further, the system control circuit 50 generates a “dark side setting program diagram” when it is found from the acquired open F value that the photographing lens 11 has a different open F value depending on the angle of view. In this case, assuming that the darkest open F value among the open F values that can be changed is F5.6 and the overall aperture upper limit value is set to 6400, a program line as illustrated in FIG. A diagram is generated. On the other hand, among the variable open F values, the darkest open F value is F5.6, and the ISO value is set to “non-open aperture upper limit (threshold)” = 3200, “open open upper limit” = 6400 If so, a program diagram as illustrated in FIG. 6 is generated.

  FIG. 8 is a flowchart of the moving image recording process. This process is started when a recording / recording instruction is issued in the moving image capturing mode and in the state where the moving image recording preparation process of FIG. 7 is completed. For example, the recording / recording instruction is instructed by turning on a dedicated button (not shown), but may be instructed by the SW2 operation of the shutter switch 62. In FIG. 8, when only the SW1 operation of the shutter switch 62 is on, Steps S302 to S309 are repeated after the processing of Step S301, and when the SW2 operation is turned on, the process proceeds from Step S309 to Step S310. It may be.

  First, the system control circuit 50 reads the program diagram generated in step S104 of FIG. 7 from the memory 52 (step S301). Next, the system control circuit 50 acquires current lens information regarding the photographing lens 11 such as the current angle of view (focal length), whether or not the angle of view is changing, and the aperture value AV. Next, the system control circuit 50 calculates the exposure from the acquired current lens information and the image information (including the subject brightness EV) obtained from the image sensor 14 (step S303).

  Here, the exposure is calculated by exposure = AV value + TV value−ISO value−exposure correction amount (arbitrary designation). Among these values, the AV value, TV value, and ISO value are obtained as values corresponding to the current subject brightness EV with reference to the program diagram read in step S301. Further, the value of the exposure correction amount is applied only when designated in advance by the user.

  Next, the system control circuit 50 performs AV value setting, which is a diaphragm change request for the photographing lens 11 (step S304). In other words, the aperture is controlled by controlling the exposure control circuit 40 so that the AV value obtained from the program diagram is obtained. Next, the system control circuit 50 performs TV value setting, which is a change request for the shutter (step S305). That is, the exposure control circuit 40 is controlled to control the shutter speed (charge accumulation time) so that the TV value obtained above is obtained.

  Next, the system control circuit 50 sets the ISO value so as to be the ISO value obtained above (step S306), and reads the captured current frame image from the memory 30 (step S307). Next, the system control circuit 50 performs image correction such as white balance, contrast correction, and noise removal on the read image data (step S308). Further, the system control circuit 50 synthesizes information such as a display icon and a histogram with the image data, and displays an image on the image display unit 28 (step S309).

  Next, in step S310, the system control circuit 50 generates an image necessary for moving image recording and performs file writing (step S310). That is, the current frame image is recorded on the recording media 200 and 210. Next, the system control circuit 50 determines whether or not an instruction to end moving image recording has been issued (step S311). The end of moving image recording is instructed by the reverse operation of the recording / recording instruction, for example, by turning off a dedicated button (not shown).

  If the result of the determination is that there is no instruction to end moving image recording, the system control circuit 50 returns the processing to step S302 for reading the next frame image. On the other hand, when an instruction to end moving image recording is given, the moving image recording process ends. In this way, by reducing the aperture drive without degrading the AE performance, the viewfinder performance and the image quality degradation that occur during the aperture drive are suppressed.

  According to the present embodiment, when a moving image is picked up, a “dark side setting program diagram” is generated when a lens whose open F-number is changed depending on the angle of view is generated (FIG. 5C). Exposure control is performed using it. That is, the aperture value is controlled so that the darkest open F value among the open F values that can be changed by the lens is set as the limit aperture value on the bright side. As a result, it is possible to suppress image quality deterioration due to a change in aperture value accompanying a change in the angle of view when capturing a moving image.

  In addition, when a lens whose open F value is changed depending on the angle of view is mounted and an aperture upper limit value (threshold value) other than the full aperture is set, the “dark side” is switched such that the brighter limit aperture value is switched with the threshold as a boundary. A “setting program diagram” is generated (FIG. 6), and exposure control is performed using it. In other words, in the range of the subject brightness EV where the ISO value does not exceed the threshold value, the aperture value AV is controlled so that the darkest open F value is the brightest limit aperture value. Then, in the range of the subject brightness EV where the ISO value exceeds the threshold value, the aperture value AV is controlled to be set with the open F value corresponding to the angle of view as the brightest limit aperture value. This makes it possible to set the open aperture value according to the angle of view as the aperture value in a dark environment while suppressing image quality deterioration due to the change in the aperture value due to the change in the angle of view. Deterioration can be suppressed.

(Second Embodiment)
In the second embodiment of the present invention, in the moving image recording process (FIG. 8) in the first embodiment, whether or not to freeze the image further based on the moving body speed and the fluctuation amount of the aperture value AV. Add control. Therefore, the moving image recording process will be described with reference to FIG. 9 instead of FIG. 8, and the second embodiment will be described with reference to FIGS. Other configurations and processes are the same as those in the first embodiment.

  FIG. 9 is a flowchart of the moving image recording process in the second embodiment. The start condition of this process is the same as that in FIG. Further, when only the SW1 operation of the shutter switch 62 is on, after the processing of step S401, steps S402 to S414 may be repeated, and when the SW2 operation is turned on, the process may proceed from step S414 to step S415. .

  First, in steps S401 and S402, the system control circuit 50 executes processing similar to that in steps S301 and S302 in FIG. Next, the system control circuit 50 controls the angle-of-view variation calculation unit 43 to compare the lens information in the previous frame (previous frame) with the lens information in the current frame (current frame), and between the frames. An angle of view variation is calculated (step S403). For example, when recording a moving image at a frame rate of 30 FPS, if the angle of view of the previous frame is 35 mm and the angle of view of the current frame is 40 mm, the angle of view changes by 5 mm in 33.3 ms.

  Next, the system control circuit 50 compares the image information in the previous frame with the image information in the current frame, and detects (calculates) the displacement speed of the moving body between the frames (step S404). For example, the movement amount detection unit 59 is controlled to compare the position and size information of the face obtained by the face detection of the face detection unit 58 between the previous frame and the current frame, and the moving object is moved based on the comparison result. Calculate the amount. Then, the displacement speed of the moving object is calculated from the calculated moving amount of the moving object and the time interval. The face detection method will be described later. It is assumed that the image of the current frame is stored in the image display memory 24 or the memory 30 until at least processing of the next frame. Further, it is assumed that the field angle fluctuation amount, the moving amount of the moving object, and the displacement speed of the moving object are also stored and accumulated for a certain period.

  Next, in steps S405 to S408, the system control circuit 50 performs the same processing as steps S303 to S306 in FIG. 8 for the current frame. It is assumed that the exposure control values (AV value, TV value, ISO value) relating to the current frame obtained in step S405 are stored in the memory 52 until at least the processing of the next frame.

  Next, in step S409, the system control circuit 50 determines whether or not to perform image freeze related to the display of the current frame, based on the aperture value fluctuation amount and the moving body speed. That is, it is determined whether the frame image to be displayed and recorded is fixed as the previous frame or updated to the current frame. Image freeze is fixing the previous frame. The determination in step S409 is determined by the result of determination processing in FIG. If the image freeze request notification (step S505) is made, the image freeze is executed, and if the image freeze release notification (step S506) is made, the image freeze is determined not to be executed.

  If it is determined not to execute the image freeze, the system control circuit 50 shifts the process to step S410. First, the system control circuit 50 executes processes similar to those in steps S307 and S308 in FIG. 8 in steps S410 and S411. Next, in step S413, the system control circuit 50 stores the image of the current frame in the image display memory 24 and the memory 30. Next, in steps S414 and S415, the system control circuit 50 executes the same processing as in steps S309 and S310 of FIG. In this case, the current frame image is displayed and recorded on the image display unit 28.

  On the other hand, when it is determined that the image freeze is to be executed, the system control circuit 50 reads the previously stored image in the previous frame (step S411). Then, the processes in steps S414 and S415 are performed on the read image. In this case, the displayed and recorded image is an image that is not updated.

  FIG. 10 is a flowchart of the image freeze determination process. This determination process is started when step S409 in FIG. 9 is executed, and the image update determination unit 55 performs the determination process under the control of the system control circuit 50.

  First, the system control circuit 50 calculates the fluctuation amount of the aperture value AV between adjacent frames (between the previous frame and the current frame), compares the two, and the fluctuation amount of the aperture value AV is smaller than a predetermined amount. Is determined (step S501). The aperture value AV of the previous frame is acquired from the memory 52. If the fluctuation amount of the aperture value AV is smaller than the predetermined amount, the system control circuit 50 performs image freeze release notification to release the image freeze because there is little image quality deterioration due to aperture drive (step S506).

  On the other hand, if the variation amount of the aperture value AV is greater than or equal to the predetermined amount, the system control circuit 50 determines whether or not the moving body speed is faster than the predetermined speed (step S502). Here, the moving body speed is predicted based on the displacement speed or movement amount of the moving body between the frames calculated and accumulated in step S404 of FIG. 9 and the angle of view fluctuation amount between the frames calculated and accumulated in step S403. (Hold). However, the displacement speed of the moving body between the frames may be adopted as the moving body speed.

  If the predicted moving object speed is higher than the predetermined speed as a result of the determination, it is necessary to avoid the adverse effect of the moving object stopping due to image freezing. Therefore, the system control circuit 50 issues an image freeze release notification to release the image freeze (step S506). On the other hand, if the predicted moving body speed is not faster than the predetermined speed, the system control circuit 50 determines whether or not the image is currently frozen (step S503). That is, it is determined whether an image freeze request notification has been issued.

  As a result of the determination, if the image is not frozen, the effect of the moving object stopping due to the image freeze is small, and thus an image freeze request notification is performed (step S505). On the other hand, if the image is frozen, the system control circuit 50 determines whether or not an aperture drive completion notification has been received (step S504). This aperture drive completion notification is supplied from the aperture drive determining unit 49.

  As a result of the determination, if the aperture control completion notification has not been received, the system control circuit 50 issues an image freeze request notification in order to perform image freeze (step S505). On the other hand, when the system control circuit 50 receives the aperture drive completion notification, it performs an image freeze release notification (step S506). Thereafter, this process ends.

  Hereinafter, examples of face detection and moving object detection will be described.

  FIG. 11 is a flowchart of the pattern recognition process. This processing is executed by the face detection unit 58 according to control by the system control circuit 50.

  First, the face detection unit 58 preprocesses the image data acquired from the memory 30 (step S601), and extracts a characteristic part pattern from the preprocessed image data (step S602). Then, the face detection unit 58 performs template matching by matching the extracted pattern of the characteristic portion with the template 501 (FIG. 12A) based on the standard pattern of the face. The face detection unit 58 acquires a recognition pattern by this template matching (step S603), and outputs the acquired recognition pattern to the face size determination unit included in the face detection unit 58 (step S604).

  An example of template matching in step S603 will be described more specifically with reference to FIG. First, the center point 502 of the template 501 is placed at a certain coordinate point (i, j) of the acquired image data 503. Then, while scanning the center point 502 in the image data 503, the similarity of the overlapping portion between the template 501 and the image data 503 is calculated, and the position where the similarity is maximized is determined. By matching the pattern extracted from the face image data with, for example, a template 501 including shapes such as eyes and ears, coordinate information (face coordinates) indicating eye position information and a face region can be acquired.

  Other methods for detecting face image data include a method using learning using a neural network and the like, and a method of extracting a characteristic part of a physical shape from an image region. Also known is a method of statistically analyzing image features such as the detected skin color and eye shape. Furthermore, methods that have been studied for practical use include a method that uses wavelet transform and image feature amounts.

  Here, pattern recognition is a process of matching (matching) an extracted pattern with one of predetermined concepts (classes). Template matching is a method of comparing an image and a template while moving a template meaning a pattern on the image. These methods can be used, for example, for detecting the position of a target object, tracking a moving object, and aligning images with different shooting timings, and in particular, extracting physical shapes such as eyes and nose from an image region. This is a useful method for detecting face information.

  The face size determination unit of the face detection unit 58 counts the number of pixels in the face area from the detected face information, and determines the face size based on the number of pixels. The face area can be represented by, for example, coordinate information indicating an area detected as a face. However, the present invention is not limited thereto, and the face size determination unit may determine the face size based on the position information of the eyes among the detected face information. For example, it is possible to calculate the eye interval on the image data based on the eye position information, make a table using the statistical relationship between the eye interval and the face size obtained in advance, and determine the face size. Conceivable. Further, the face size may be determined by counting the number of pixels in the face area from the predetermined position of the detected face, for example, the coordinate values of the four corners.

  The face detection unit 58 estimates the subject distance from the image processing apparatus 100 to the subject based on the determined face size. More specifically, based on the determined face size, the subject distance is estimated with reference to a conversion table in a lens having a predetermined focal length created in advance from the relationship between the face size and the subject distance.

  FIG. 12B shows an example of the relationship between the face size represented by the number of pixels on the image and the subject distance. A table based on the relationship shown in FIG. 12B is created for a wide-angle lens having a lens focal length of 38 mm, and the subject distance is estimated. When the lens focal length is different from 38 mm, the conversion table is referred to using a value obtained by multiplying the determined face size by “38 mm / actual lens focal length (mm)”.

  Not limited to this, as illustrated in FIG. 12C, the relationship between the ratio of the detected face area to the image and the subject distance may be used as a table instead of the face size.

  Since the subject distance varies depending on the size of the image sensor 14 and the use area, a conversion table for calculating the estimated subject distance is regenerated according to the mode, or a plurality of conversion tables are stored in advance. You may do it.

  According to the second embodiment, the same effect as that of the first embodiment can be achieved with respect to suppressing image quality deterioration caused by a change in aperture value accompanying a change in the angle of view when capturing a moving image. . Not only that, the image is frozen only when the amount of fluctuation of the aperture value is large and the moving body speed is slow, so that the display and recording of moving movies are not disturbed, and the display of moving images with little movement and the deterioration of image quality during recording are suppressed. be able to.

  In each of the above embodiments, as a “dark side setting program diagram” that can be generated, a program diagram having a stepped straight line L as shown in FIG. 6 is also provided. However, the configuration shown in FIG. 6 may be abolished by accepting an input of only the “total aperture upper limit value” as the upper limit setting value of the ISO value. In that case, when the photographic lens 11 having a different open F value depending on the angle of view is attached, a program diagram having a straight line L as shown in FIGS. 5A to 5C is generated.

  Note that the exposure control is not limited to exposure control using a program diagram. That is, when a moving image is picked up, when a lens whose opening F value changes according to the angle of view is mounted, the aperture value AV is set with the darkest opening F value among the changing opening F values as the limit aperture value on the bright side. It only needs to be able to control to set.

  In the generated program diagrams (FIGS. 4 to 6), the horizontal axis on the lower side switches between the charge accumulation time TV and the ISO sensitivity, and the TV value or the ISO value changes with TV = 1/30 as a boundary. Only one of them was changed. However, it may be possible to generate a program diagram provided with an overlapping region where both the charge accumulation time TV and the ISO sensitivity change.

  In each of the above embodiments, the digital camera capable of exchanging the photographing lens has been described. However, the present invention can also be applied to a digital camera including a photographing lens whose open F value changes depending on the angle of view.

(Other examples)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

DESCRIPTION OF SYMBOLS 11 Shooting lens 14 Image sensor 28 Image display part 30, 52 Memory 41 Lens information acquisition part 50 System control circuit 70 Operation part 100 Image processing apparatus

Claims (7)

In an imaging device that can capture moving images,
Obtaining means for obtaining information on an open F value of a lens attached to the apparatus main body of the imaging apparatus;
Calculating means for calculating subject luminance from image information obtained by the image sensor;
Control means for controlling the exposure by setting an aperture value for adjusting the amount of light incident on the image sensor, a charge accumulation time of the image sensor, and an ISO value based on the subject brightness calculated by the calculation means. ,
The control means refers to the information on the open F value acquired by the acquisition means and can change the open F value when a lens whose open F value changes according to the angle of view is attached at the time of moving image capturing. The image pickup apparatus is controlled to set the aperture value with the darkest open F value as a limit aperture value on the bright side.   When receiving a threshold value of the ISO value, the control unit is equipped with a lens whose open F value changes according to the angle of view, and the threshold value of the ISO value is received by the reception unit. In the range of subject luminance such that the set ISO value does not exceed the threshold value, the aperture value is set with the darkest open F value as the brightest limit aperture value, and the set ISO value is the threshold value. 2. The image pickup apparatus according to claim 1, wherein the aperture value is controlled so that the open F value corresponding to the angle of view is set to a brighter limit aperture value in a range of subject luminance exceeding 1 mm.   Storage means for storing information on the open F value and information on the open F value stored in the storage means each time a new lens is mounted on the apparatus main body Update means for updating the information, and the acquisition means refers to the information on the open F value stored in the storage means, so that the open F value of the lens currently mounted on the apparatus main body. The imaging apparatus according to claim 1, wherein the information is acquired.   The control means generates a program diagram in which the darkest open F value is set as a limit aperture value on the bright side when a lens whose open F value varies with the angle of view is attached, and the generated program The imaging apparatus according to claim 1, wherein control is performed to set the aperture value, the charge accumulation time, and the ISO value using a diagram.   A calculating means for calculating a fluctuation amount of an aperture value between adjacent frames from an aperture value set by the control means for the previous frame in moving image capturing and an aperture value set by the control means for the current frame; The storage means for storing the image in the previous frame, the grasping means for grasping the moving object speed in the subject, the variation amount of the aperture value calculated by the calculating means, and the moving object speed grasped by the grasping means And determining means for determining whether or not to execute image freeze related to the display of the current frame, and when the control means determines that the image freeze is not to be executed, the control means It is determined that the image in the frame is displayed on the display device and the image freeze is performed by the determination unit. The case, the imaging apparatus according to any one of claims 1 to 4, characterized in that controls to display the image in the previous frame stored in the storage unit on the display device. In an exposure control method in an imaging apparatus capable of capturing moving images,
An acquisition step of acquiring information on an open F value of a lens attached to the apparatus main body of the imaging apparatus;
A calculation step of calculating subject luminance from image information obtained by the image sensor;
A control step for controlling exposure by setting an aperture value for adjusting the amount of light incident on the image sensor, a charge accumulation time of the image sensor, and an ISO value based on the subject brightness calculated by the calculation step. ,
The control step refers to information on the open F value acquired by the acquisition step and can change the open F value when a lens whose open F value changes according to the angle of view is attached at the time of moving image capturing. An exposure control method for an image pickup apparatus, wherein the darkest open F value is set as the limit aperture value on the bright side, and the aperture value is set.   A program causing a computer to execute the exposure control method in the imaging apparatus according to claim 6.

Images