JP2011130031A - Imaging apparatus, and control method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow recording of a moving image, captured with proper exposure, even if a start instruction of moving-image recording is issued in a state that live view display is not performed. <P>SOLUTION: If a start instruction of moving-image recording is detected while live view display is not performed, an imaging apparatus automatically sets a combination of exposure parameters allowing it to obtain proper exposure about subject luminance. After setting the combination of exposure parameters as the exposure parameters for moving-image photographing, the moving-image recording is started. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly to an exposure control technique for an imaging apparatus.

  In an imaging device such as a digital still camera or a digital video camera, a subject image formed by an optical system is converted into an electrical signal in units of pixels using an imaging device such as a CCD image sensor or a CMOS image sensor, and is used as image data. Record. In recent years, a digital still camera having a moving image capturing function is also common, and many of the imaging devices can capture a moving image.

  Further, in an imaging apparatus using an imaging element, it is generally performed that a display device functions as an electronic viewfinder during imaging standby of moving images and still images and during moving image imaging. Specifically, moving image imaging is performed, and the captured moving image is displayed on the display device in real time. Since imaging and display are performed in real time, such a display method is also called live view display.

  When a user captures (records) a moving image, the electronic shutter speed, aperture value, and so on are displayed so that a moving image in a desired exposure state is displayed after the image capturing apparatus is in an imaging standby state. Adjust the values of exposure parameters such as imaging sensitivity. In general, a recording start instruction is input by pressing a shutter button at a desired timing. Note that there are imaging devices that automatically start live view display in the imaging standby state, and there are imaging devices that perform live view display after an instruction to start live view display is given. In the latter case, it is necessary to press a predetermined button or the like in order to start live view display after entering the imaging standby state.

  On the other hand, in order to cope with a case where the user wants to start moving image recording immediately, the imaging apparatus has a function of starting moving image recording if there is a moving image recording start instruction even when the live view is not displayed. However, when recording is started without live view display, moving image recording is started without adjusting the exposure parameter, so an image captured with an appropriate exposure value cannot be recorded depending on the scene. There is also.

  In Patent Document 1, in order to reduce the time difference from when the release button is fully pressed to when still image capturing is started, the exposure conditions used for moving image capturing for live view display are released. And when half-pressed. Specifically, when the release button is pressed halfway, the aperture value used for moving image capturing for live view display is changed to the aperture value for still image capturing.

JP 2005-260733 A

  However, in Patent Document 1, the exposure parameter of a moving image cannot be changed unless the release button is pressed halfway during live view display. Further, although there is disclosure that the exposure condition for live view display in the still image recording mode is changed for still image capturing, the exposure parameter is not changed in the moving image recording mode. Further, the present invention is an invention for changing the exposure parameter of a moving image for live view display, and no problem is assumed when moving image recording is started from a state where the live view is not displayed.

  The present invention has been made in view of such problems of the prior art, and records a moving image captured with an appropriate exposure value even when moving image recording is started without live view display. It is an object of the present invention to provide an imaging device capable of performing the same and a control method thereof.

  In order to achieve the above-described object, an imaging apparatus of the present invention includes an image sensor, a live view display function for displaying a moving image captured by the image sensor on a display device in real time, and a moving image captured by the image sensor. An imaging device having a function of recording on a recording medium, a measuring unit that measures subject luminance, a storage unit that stores a combination of exposure parameters for obtaining appropriate exposure for each different subject luminance, and a display device Recording by a determination unit that determines whether or not a live view is being displayed, a detection unit that detects an instruction to start recording a moving image, a setting unit that sets an exposure parameter when a moving image is captured by an imaging device, and a detection unit When a start instruction is detected, the recording unit records a moving image captured with the exposure parameter set by the setting unit on a recording medium. When the moving image recording start instruction is detected by the detecting means when it is determined that the display device is not displaying the live view, it is obtained using the subject luminance detected by the measuring means and the storage means. The exposure parameter is set as an exposure parameter for capturing a moving image to be recorded in response to a recording start instruction.

  With such a configuration, according to the present invention, even when moving image recording is started in a state where live view display is not performed, it is possible to record a moving image captured with an appropriate exposure value.

1 is a block diagram illustrating an example of a functional configuration of a digital still camera as an example of an imaging apparatus according to an embodiment of the present invention. It is a flowchart for demonstrating the exposure parameter setting operation | movement for video recording in DSLR which concerns on embodiment of this invention. FIG. 4A is a flowchart for explaining details of the processing in S14 of FIG. 2, and FIG. 4B is a diagram showing an example of a first program diagram used in S102 of FIG. FIG. 5A is a flowchart for explaining details of the processing in S13 of FIG. 2, and FIG. 5B is a diagram showing an example of a second program diagram used in S205 of FIG.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are for the purpose of explaining the present invention, and should not be construed as limiting the present invention. In addition, all the configurations described in the embodiments are not necessarily essential to the present invention.

  FIG. 1 is a block diagram illustrating a functional configuration example of a lens interchangeable single-lens reflex digital still camera (DSLR) as an example of an imaging apparatus according to an embodiment of the present invention. Note that the present invention can be applied to any imaging apparatus having a live view display function for capturing moving images and displaying captured moving images on a display device in real time and a function for recording moving images. In this specification, the “imaging device” includes not only a so-called camera but also a device with a built-in or connected imaging device (a mobile phone, a personal digital assistant, a computer, a media player, etc.). Note that the present invention can also be applied to an imaging device having a fixed lens.

  The DSLR 100 has a configuration in which a replaceable lens unit 100 is connected to the main body 200 by a lens mount. Although the lens 5 included in the lens unit 100 is illustrated as a single lens for convenience, it is usually configured by a combination of a plurality of lenses including a focus adjustment lens. The communication terminal 6 provided in the lens unit 100 is a communication terminal for the lens unit 100 to communicate with the main body 200 and is electrically connected to the communication terminal 10 provided in the main body 200.

  The lens control unit 4 of the lens unit 100 communicates with the camera control unit 39 via the communication terminals 6 and 10, and controls the aperture drive unit 2 and the AF drive unit 3 according to the control of the camera control unit 39, thereby The size of 1 and the focusing distance of the lens 5 are changed.

  The AE sensor 15 measures the luminance of the subject through the lens unit 100 and outputs the measurement result to the camera control unit 39. The camera control unit 39 calculates, for example, the driving amount of the focus lens included in the lens 5 based on the defocus amount information acquired from the AF sensor 11 of the phase difference detection method, and notifies the lens control unit 4 of the driving amount. The quick return mirror 12 is instructed by the camera control unit 39 during exposure and is raised and lowered by an actuator (not shown).

  Further, the user can confirm the focus and composition of the optical image of the subject obtained through the lens unit 100 by observing the focusing screen 13 via the pentaprism 14 and the optical viewfinder 16.

  The focal plane shutter (hereinafter referred to as a mechanical shutter) 17 is controlled to be opened and closed by a timing control unit 32 in accordance with the exposure time of the image sensor 20. The optical filter 18 is generally composed of a low-pass filter, an infrared cut filter, or the like, and cuts high-frequency components and infrared rays of light incident from the opening of the mechanical shutter 17.

  A photoelectric conversion element such as a CCD image sensor or a CMOS image sensor is generally used as the image sensor 20, and a subject image formed on the image sensor 20 through the lens unit 100, the mechanical shutter 17, and the optical filter 18 is pixel by pixel. Convert to electrical signal.

  The AMP unit 21 amplifies the electronic signal obtained by the imaging element 20 with a gain corresponding to the set imaging sensitivity. The A / D converter 22 converts the electric signal amplified by the AMP unit 21 into a digital signal (image data).

  The image processing unit 23 performs filter processing, color conversion processing, and gamma / knee processing on the image data output from the A / D conversion unit 22 and outputs the result to the memory controller 27. The image processing unit 23 has a built-in D / A conversion unit, and the D / A conversion unit converts image data output from the A / D conversion unit 22 and image data input from the memory controller 27 into analog signals. It can be output to the display device 25 via the display control unit 24. Image processing and display processing by the image processing unit 23 are controlled by the camera control unit 39. In addition, the camera control unit 39 performs white balance adjustment based on the color balance information of the captured image.

  The memory controller 27 stores unprocessed image data input from the image processing unit 23 in the buffer memory 26, and stores image processed image data input from the image processing unit 23 in the memory 28. The memory controller 27 reads out image data from the buffer memory 26 and the memory 28 and outputs the image data to the image processing unit 23. Further, the memory controller 27 can store the image data input via the interface 29 in the memory 28, and conversely output the image data stored in the memory 28 to the outside via the interface 29. . The interface 29 may be compliant with standards such as USB (Universal Serial Bus), IEEE (Institute of Electrical and Electronics Engineers) 1394, and HDMI (High-Definition Multimedia Interface).

  The memory 28 is a recording medium for recording a moving image for recording and a still image captured by the DSLR. The memory 28 may be fixed to the main body 200 or may be detachable like a semiconductor memory card. FIG. 1 shows the detachable aspect. The timing control unit 32 controls the drive timing of the image sensor 20 according to the control of the camera control unit 39.

  The operating power of the DSLR of this embodiment is supplied from the AC power supply unit 30 or the secondary battery unit 31 (collectively referred to as a power supply). The power supply control unit 35 receives an instruction from the camera control unit 39 and turns on / off the power supply from the power supply. The power control unit 35 notifies the camera control unit 39 of information on the current power supply state detected by the power supply state detection unit 34 and information on the current power supply type detected by the power supply type detection unit 33.

  The shutter control unit 36 controls the opening and closing of the mechanical shutter 17 according to the control of the camera control unit 39. The optical filter vibration control unit 37 vibrates the piezoelectric element 19 connected to the optical filter 18 under the control of the camera control unit 39. The camera control unit 39 designates the amplitude for vibrating the piezoelectric element 19, the vibration time, and the axial direction of vibration.

The non-volatile memory 38 stores setting values and data such as shutter speed, aperture value, and imaging sensitivity arbitrarily set by the user even in the power-off state. The nonvolatile memory 38 may be, for example, an EEPROM.
The camera control unit 39 includes, for example, a CPU and a memory such as a ROM and a RAM, and controls the operations of the main body 200 and the lens unit 100 when the CPU executes a control program stored in the ROM.

  The operation unit 40 is an input device group such as keys, buttons, and dials for the user to make various settings and instructions to the DSLR. The operation unit 40 includes a release button, a mode dial, a direction key, an enter key, a power switch, a live view display start button, a menu button, and the like. In the present embodiment, it is assumed that a still image recording mode (including an aperture / shutter speed priority AE mode, a manual mode, etc.) and a moving image recording mode can be switched by a mode dial. In addition, the release button functions as a still image recording start button in both the still image recording mode and the moving image recording mode. In addition, a moving image recording start button is provided separately from the release button, and moving image recording is started when the moving image recording start button is pressed in either the still image recording mode or the moving image recording mode. . However, the function assignment to the buttons is not limited to this, and the same button that functions as a moving image recording start button in the moving image recording mode and as a still image recording start button in the still image recording mode may be provided.

Next, the exposure parameter setting operation for moving image capturing in the DSLR of this embodiment will be described using the flowchart of FIG. The operation of FIG. 2 is executed by the camera control unit 39 at regular intervals, for example, at the time of imaging standby even in the still image recording mode or the moving image recording mode.
First, in S10, the camera control unit 39 determines whether a live view is being displayed. This determination can be realized, for example, by storing information indicating whether or not the live view is being displayed in the nonvolatile memory 38 and referring to this information at the time of determination. The camera control unit 39 updates the information value when the live view display is started or ended, for example, by pressing a live view display start button. If it is determined in S10 that the live view is being displayed, the camera control unit 39 advances the process to S20, and performs a moving image recording standby process similar to the conventional one. On the other hand, if it is determined in S10 that the live view is not being displayed, the camera control unit 39 advances the process to S11.

  In S <b> 11, the camera control unit 39 determines whether a live view display start instruction such as pressing of a live view display start button has been issued. If the input of the live view display start instruction is detected, the camera control unit 39 advances the process to S13, and if not detected, advances the process to S12.

In S12, the camera control unit 39 determines whether a moving image recording start instruction such as pressing of a moving image recording start button has been issued. If the input of the moving image recording start instruction is detected, the camera control unit 39 advances the process to S14, and if not detected, returns the process to S10.
In S13, the camera control unit 39 sets the electronic shutter speed, the imaging aperture, and the imaging sensitivity as exposure setting values when capturing a moving image for live view display. A detailed setting method will be described later.

In S14, the camera control unit 39 sets the electronic shutter speed, the imaging aperture, and the imaging sensitivity as the exposure setting values at the time of moving image recording for moving image recording. A detailed setting method will be described later.
In S15, the camera control unit 39 operates an actuator (not shown) to raise the quick return mirror 12.

In S16, the camera control unit 39 transmits the aperture value set in S13 or S14 to the lens control unit 4 via the communication terminals 10 and 6. The lens control unit 4 drives the aperture 1 via the aperture drive unit 2 so that the aperture value specified by the camera control unit 39 is obtained.
In S <b> 17, the camera control unit 39 opens the mechanical shutter 17 through the shutter control unit 36.

  In S18, the camera control unit 39 starts capturing a moving image for live view display or recording, using the exposure condition set in S13 or S14. The camera control unit 39 notifies the timing control unit 32 of the electronic shutter speed set in S13 or S14, and the timing control unit 32 controls the drive timing of the image sensor 20 so as to realize the notified electronic shutter speed. To do. As a result, an image corresponding to the frame rate of the moving image (for example, 30 frames / second) is output from the image sensor 20. Further, the camera control unit 39 sets a gain corresponding to the imaging sensitivity set in S13 or S14 for the AMP unit 21. The image data level-adjusted by the AMP unit 21 and converted into a digital signal by the A / D conversion unit 22 is subjected to the above-described image processing by the image processing unit 23 and then written to the buffer memory 26 by the memory controller 27. .

  In S <b> 19, the memory controller 27 records the image data written in the buffer memory 26 in the memory 28 via the memory controller 27. When the image data written in the buffer memory 26 is recorded in the memory 28, the image processing unit 23 performs an encoding process as necessary, or has a data structure according to a predetermined moving image file format. It may be recorded as a file.

  In addition, the image processing unit 23 converts the image data written in the buffer memory 26 into a format suitable for display on the display device 25, and outputs it to the display device 25 via the display control unit 24. When recording a moving image, live view display and recording are performed in parallel.

Next, with reference to FIGS. 3A and 3B, the exposure setting value setting process at the time of recording moving image shooting in S14 will be described in detail.
First, in step S <b> 101, the camera control unit 39 acquires the luminance (EV value) of the subject from the AE sensor 15.
In S102, the camera control unit 39 performs exposure from the subject brightness acquired in S101 according to a first program diagram prepared for moving image recording among a plurality of program diagrams stored in advance in the nonvolatile memory 38, for example. Set the parameters. The exposure parameters set here are the electronic shutter speed, the aperture value, and the imaging sensitivity.

A specific example of the first program diagram is shown in FIG. The program diagram shows a combination of exposure parameters for obtaining proper exposure for different subject brightness.
FIG. 3B is a program diagram for setting exposure parameters (in this case, electronic shutter speed, aperture value, and imaging sensitivity) so that an appropriate exposure is obtained regardless of the user setting value. In the first program diagram, the aperture value and imaging sensitivity are set so that the electronic shutter speed does not become lower than the reciprocal of the frame rate. In the example of FIG. 3B, when the frame rate of the moving image is 30 fps, and the subject brightness is lower than 1/30 seconds, the imaging sensitivity is increased without increasing the electronic shutter speed. Is set to obtain proper exposure. Therefore, by setting the exposure condition according to the first program diagram, even when the subject brightness is low and the proper exposure cannot be obtained with the user setting value, the moving image with the proper exposure is set at the designated frame rate. It becomes possible to image.

  When the camera control unit 39 selects the first program diagram, the camera control unit 39 ignores the exposure parameter value (user setting value) set at the time when the moving image recording start instruction is detected, and determines the subject brightness and the first program diagram. Obtain and set the electronic shutter speed, aperture value, and imaging sensitivity from the program diagram. For example, it is assumed that the subject brightness is EV5 when the user has set the imaging sensitivity ISO100 and the aperture value AV5.6. In this case, it is necessary to set the aperture value to 1 in order to perform imaging with proper exposure at 30 fps (electronic shutter speed 1/30 seconds). For this reason, if an image is picked up with the user-set aperture value AV5.6, the image is under 5 steps and a considerably dark moving image is recorded. On the other hand, when an exposure parameter is set from the first program diagram and the subject luminance value, an electronic shutter speed 1/30 (second), an aperture value AV2.0, and an imaging sensitivity ISO400 are set, and a moving image with appropriate exposure is set. Can be recorded.

Next, with reference to FIGS. 4A and 4B, the exposure setting value setting process at the time of moving image shooting for live view display in S13 will be described in detail.
First, in step S <b> 201, the camera control unit 39 acquires the luminance (EV value) of the subject from the AE sensor 15.
In step S202, the camera control unit 39 determines whether the currently set imaging mode is the aperture priority AE mode. If the imaging mode is the aperture priority AE mode, the process proceeds to step S204. If the imaging mode is not the aperture priority AE mode, the process proceeds to step S203. Proceed to In the aperture priority AE mode, the electronic shutter speed is automatically set according to the subject brightness. However, the setting of the imaging sensitivity is not automatically set, and the setting value remains unchanged.

In S203, the camera control unit 39 determines whether or not the currently set imaging mode is the manual mode. If the imaging mode is the manual mode, the process proceeds to 206. If not, the process proceeds to S207.
In S <b> 204, the camera control unit 39 reads the aperture value set by the user from the nonvolatile memory 38.

In step S205, the camera control unit 39 sets exposure parameters according to a second program diagram prepared in advance for moving image shooting for live view display, based on the subject brightness acquired in step S201 and the aperture value acquired in step S204. To do. The exposure parameter set using the second program diagram is the electronic shutter speed.
In S206, the camera control unit 39 uses the electronic shutter speed, aperture value, and imaging sensitivity set by the user as they are.
In step S207, the camera control unit 39 sets the electronic shutter speed, the aperture value, and the imaging sensitivity according to the first program diagram using the subject brightness acquired in step S201, as in step S14.

Here, the second program diagram will be described with reference to FIG. FIG. 4B is a program diagram when the imaging sensitivity ISO100 is set, and the frame rate of live view display is 30 fps.
For example, when the aperture value set by the user is AV16 and the subject brightness is EV13, appropriate exposure can be obtained at an electronic shutter speed of 1/30 seconds. In this way, combinations of exposure parameters that can obtain appropriate exposure at a shutter speed of 1/30 seconds or less of the electronic shutter speed are shown in the second program diagram. However, for example, when the aperture value set by the user is AV5.6 and the subject brightness is EV5, in order to capture an image with proper exposure, the electronic shutter speed must be 1 (second) or the imaging sensitivity must be ISO3200. Don't be. However, since the imaging sensitivity is set to ISO 100 and the frame rate is 30 fps, the electronic shutter speed is 1/30 (second) at the longest. Since these exposure parameters cannot be changed, the exposure is under 5 steps and the image displayed in the live view is considerably darkened. However, at this time, the video recording is not started, and only the live view is displayed, so the user changes the aperture value and imaging sensitivity settings while viewing the live view displayed image, An appropriate exposure value can be set.

  As described above, in an imaging apparatus having a live view display function and a moving image recording function, when live view display is started, the exposure parameter is set with priority given to the user setting value even if proper exposure is not obtained. Set. On the other hand, when the start of moving image recording is instructed without displaying the live view, the imaging apparatus automatically sets the exposure parameter so that a moving image captured with proper exposure can be recorded. For this reason, it is possible to record a moving image captured with proper exposure even when imaging with appropriate exposure cannot be performed with the exposure parameters set by the user.

Claims (4)

An imaging apparatus having an imaging element and having a live view display function for displaying a moving image captured by the imaging element on a display device in real time and a function for recording a moving image captured by the imaging element on a recording medium. ,
Measuring means for measuring subject brightness;
Storage means for storing a combination of exposure parameters for obtaining appropriate exposure for each of different subject luminances;
Determining means for determining whether or not the display device is displaying a live view;
Detecting means for detecting an instruction to start recording a moving image;
Setting means for setting an exposure parameter when capturing a moving image with the image sensor;
When the recording start instruction is detected by the detection unit, the recording unit records a moving image captured with the exposure parameter set by the setting unit on the recording medium,
The setting means is detected by the measuring means when the moving image recording start instruction is detected by the detecting means when the determining means determines that the display device is not in live view display. An imaging apparatus characterized in that an exposure parameter obtained using the subject brightness and the storage means is set as an exposure parameter for capturing a moving image to be recorded in response to the recording start instruction. The detection means also detects a start instruction of live view display,
When the determination unit detects that the display unit is not in live view display and the detection unit detects the start of the live view display, the setting unit cannot obtain an appropriate exposure. However, the exposure parameter set at the time when the start instruction for the live view display is detected is set as the exposure condition for capturing the moving image to be displayed in the live view corresponding to the start instruction for the live view display. The imaging apparatus according to claim 1, wherein:   The storage means stores a combination of an electronic shutter speed, an aperture value, and an imaging sensitivity as a combination of the exposure parameters, and the combination of the exposure parameters is determined based on the reciprocal of the frame rate of the live view display. The imaging apparatus according to claim 1, wherein the imaging apparatus is determined so as not to be slow. A method for controlling an imaging apparatus having an imaging element and having a live view display function for displaying a moving image captured by the imaging element on a display device in real time and a function for recording a moving image captured by the imaging element on a recording medium Because
A measurement process for measuring subject brightness;
A determination step of determining whether or not the display device is displaying a live view;
A detection step of detecting an instruction to start recording a moving image;
A setting step for setting an exposure parameter when capturing a moving image with the image sensor;
When the recording start instruction is detected in the detection step, a recording step of recording a moving image captured with the exposure parameter set in the setting step on the recording medium,
The setting step is detected by the measurement step when an instruction to start recording the moving image is detected in the detection step when it is determined in the determination step that the display device is not in live view display. A moving image that records exposure parameters obtained by using a storage unit that stores a combination of exposure parameters for obtaining appropriate exposure for each of the different subject luminances, and corresponding to the recording start instruction. A method for controlling an image pickup apparatus, wherein the method is set as an exposure parameter for image pickup.

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