JP2011048097A - Imaging apparatus and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform photography with appropriate emitted light quantity without making a release time lag long even under flicker environment of a light line being external light when consecutively performing photography by arithmetically calculating a plurality of normal emitted light quantities by a plurality of number of times by using an illuminator. <P>SOLUTION: When a photometric value in a light non-emission state obtained before arithmetically calculating the first normal emitted light quantity is equal to or under a predetermined value, the normal emitted light quantity is arithmetically calculated by using the photometric value in the light non-emission state obtained when light is not emitted before arithmetically calculating the first normal emitted light quantity, and a photometric value in a preliminary light emission state obtained when performing preliminary light emission to be performed prior to the normal light emission. <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 imaging apparatus capable of taking a picture by controlling a light emission amount of an illumination apparatus and a control method thereof.

  In an imaging device such as a digital camera, when a subject is imaged using an illumination device (hereinafter referred to as a flash), the color of the subject image obtained varies depending on the intensity of the flash. For example, when a subject is imaged outdoors with strong sunlight, if the flash emission amount is set large, a phenomenon called “whiteout” occurs, and a subject image whose contrast is difficult to distinguish is obtained. For this reason, in an imaging device that performs imaging using a flash, the flash is pre-flashed prior to the main flash at the time of main shooting, and the flash emission amount (flash emission) at the time of main flash is based on the photometric value of the subject at the time of preliminary flash. Conventionally, a method for controlling the intensity and the light emission time is used. In Patent Document 1, a compression-type photometric sensor is used as a sensor for measuring reflected light of a subject, and a photocurrent obtained by converting the reflected light of the subject is compressed and output as a voltage to obtain a photometric value. Techniques for measuring are disclosed.

  When preliminary light emission is performed and the amount of flash light emitted during main light emission is determined, the reflected light from the subject during the preliminary light emission includes both reflected light from the flash and reflected light from outside light. In order to determine the light emission amount of the main light emission, it is necessary to extract only the component of the reflected light from the flash obtained by removing the component of the reflected light from the external light from the reflected light from the subject. Therefore, after measuring the reflected light due to the external light of the subject in advance, the subject at the time of preliminary light emission is measured, and the photometric value of the reflected light due to the external light is subtracted from the photometric value at the time of preliminary light emission. A component of reflected light can be obtained.

  FIG. 3A shows the photometric values (A1, A2) of the subject before preliminary light emission in each flash when shooting with two flashes as in multi-flash photography, and the preliminary light emission. It is a figure showing the photometric value (F1, F2) of a to-be-photographed object. In order to determine the light emission amounts of the two flashes during the main light emission, the main light emission amounts of the two flashes are determined based on the photometric values obtained by performing the photometry before and during the preliminary light emission for each flash.

  However, when photographing under a power line such as a fluorescent lamp, there is a flicker of the power line that is external light. Therefore, in the photometric value of the subject before preliminary light emission and the subject photometric value during preliminary light emission, external light The reflected light component of the subject will change. In Patent Document 2, as shown in FIG. 2A, after measuring the reflected light A11 of the subject by the external light, the reflected light F11 of the subject at the time of preliminary light emission is measured almost continuously to measure the electric light that is the external light. A technique for reducing the effect of flicker is disclosed.

Japanese Patent Application Laid-Open No. 11-288024 Japanese Patent Laid-Open No. 9-54364

  However, when a compression-type photometric sensor is used, it takes time for the output voltage to stabilize even if the amount of light incident on the photometric sensor changes due to the parasitic capacitance present in the compression circuit. Therefore, when imaging using two flashes in an environment of flickering of the electric power line that is external light, using a compression-type photometric sensor, when performing photometry for each flash before and during preliminary light emission, The following problems occur. For example, as shown in FIG. 2B, the subject is measured before and during the preliminary light emission of the first flash (A21, F21), and then the subject before and during the preliminary light emission of the second flash. Let us consider the case of photometry (A22, F22). At this time, the photometric value A22 before preliminary light emission of the second flash is the voltage at the time of performing photometry at the time of preliminary light emission of the first flash, so the photometric value A22 is shown in FIG. It becomes higher than the photometric value that should be originally obtained as shown in (b). For this reason, the reflected light component of the subject due to the preliminary light emission of the second flash cannot be obtained correctly.

  Further, as shown in FIG. 2 (c), before the preliminary light emission of the second flash, and before the preliminary light emission of the second flash, an interval is provided after the preliminary light emission of the first flash so that the parasitic capacitance existing in the compression circuit is eliminated. By performing photometry, the problem of the voltage remaining in the compression circuit can be avoided. However, in this method, since the preliminary light emission operation for determining the main light emission amount takes time, the release time lag becomes long. In addition, when continuous imaging is performed, such as during continuous shooting, the main flash emission amount for one imaging operation is determined, so that a problem arises that the release time lag becomes long even when preliminary light emission is performed each time. .

  The present invention has been made in view of the above-described problems, and when shooting using an illumination device, without increasing the release time lag even in an environment of flickering of power lines that are external light, The purpose is to take a picture with an appropriate amount of light emission.

  In order to achieve the above-described object, an imaging apparatus according to the present invention is an imaging apparatus capable of photographing using an illumination device that emits light toward a subject, and includes imaging means for imaging the subject, and photometry of the subject. Based on the photometric means, the non-light-emission photometric value obtained by the photometry means when the illuminating device is not lit, and the preliminary light-emission photometric value obtained during the preliminary luminescence performed prior to the main luminescence of the illuminating device, Calculating means for calculating the main light emission amount of the lighting device, and when the calculation means calculates a plurality of main light emission amounts in succession, it is obtained by the photometry means before the calculation of the first main light emission amount. If the non-light-emission photometric value is less than or equal to a predetermined value, the main light emission amount is calculated based on the non-light-emission photometry value and the preliminary light-emission photometry value obtained during the preliminary light emission performed prior to each main light emission. It is characterized by calculating.

  With such an arrangement, according to the imaging apparatus of the present invention, when shooting using an illuminating device, appropriate light emission can be achieved without increasing the release time lag even in the environment of flickering of power lines that are external light. You can shoot in quantity.

1 is a block diagram showing an example functional configuration of an imaging apparatus and a flash according to an embodiment of the present invention. The figure for demonstrating the preliminary light emission process in the flicker environment of the electric power line which is external light. A figure showing the photometric value in the preliminary light emission processing in the flicker environment of the power line that is external light 7 is a flowchart for explaining imaging processing of the imaging apparatus. 7 is a flowchart for explaining light emission amount determination processing of the imaging apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described below is an example in which the present invention is applied to a digital camera that controls the amount of light emitted from two flashes as an example of an image pickup apparatus and can emit images by emitting two flashes during image pickup. explain. However, the present invention is not limited to two flashes, but can be applied to any device that can control the amount of light emitted from a plurality of flashes and perform imaging by linking the plurality of flashes.

  FIG. 1 is a block diagram illustrating a functional configuration example of a digital camera according to an embodiment of the present invention. In the digital camera 100 of the present embodiment, a detachable flash 200 is used as two controllable flashes, and a first flash that is used by being mounted on the digital camera 100, and a first flash that is installed externally without being mounted. Two flashes shall be provided. The second flash installed and used has the same function as the flash 200 (first flash) used by being mounted on the digital camera 100, and communicates with the first flash mounted on the digital camera 100 to emit light. Control the amount.

  The camera control unit 101 is a CPU, for example, and controls the operation of each block of the digital camera 100. The camera control unit 101 expands and executes an operation program for each block of the digital camera 100 stored in the camera ROM 102 in the RAM 103, for example, and controls the operation of each block of the digital camera 100. The camera control unit 101 can communicate with a flash control unit included in the flash 200 described below via a connection contact (not shown), and can transmit an operation instruction to the flash 200. The camera ROM 102 is a rewritable nonvolatile memory, for example, and stores an operation program for each block of the digital camera 100 and various settings of the digital camera 100. Various settings of the digital camera 100 include, for example, information on the resolution of an image to be captured, and information related to imaging such as the presence / absence of automatic focusing and the presence / absence of flash use. The operation input unit 104 has a user input interface provided in the digital camera 100 such as a power button, a release button, and an FE lock button, for example, receives input from the user to each button, and inputs to the camera control unit 101. Tell what happened.

  The optical system 105 is an imaging lens group having, for example, a focusing lens and a diaphragm, and takes in reflected light that enters from a subject into the digital camera 100. The imaging unit 106 is, for example, an imaging device, photoelectrically converts reflected light from a subject that has entered through the optical system 105, and transmits the obtained analog image data to the A / D conversion unit 107. The A / D conversion unit 107 applies A / D conversion processing to the analog image data input from the imaging unit 106 and outputs digital image data. The photometry unit 108 is a compression-type multi-division photometric sensor, acquires photometric value (luminance) information for each multi-division area from the reflected light from a subject incident through the optical system 105, and Output to the control unit 101. When the setting of the digital camera 100 stored in the camera ROM 102 is set to perform the automatic focusing, the focusing unit 109, for example, from the contrast information of the digital image data output from the A / D conversion unit 107, the subject The position of the focusing lens that is focused on is calculated. The camera control unit 101 drives the focusing lens of the optical system 105 using a focusing lens driving unit (not shown) according to the focusing lens position information obtained by the focusing unit 109 to focus on the subject. I'm irritated. The image processing unit 110 applies various image processing such as resolution conversion processing and color tone conversion processing to the digital image data output from the A / D conversion unit 107 and records the digital image data on a recording medium (not shown). The image display unit 111 is a display device such as a small LCD, for example, and sequentially displays the image of the subject formed by the imaging unit 106 (through display). The image display unit 111 not only functions as an electronic viewfinder by through display, but also displays, for example, a GUI for setting the digital camera 100 and an image recorded on a recording medium.

  The flash 200 is a flash that is detachably attached to the digital camera 100. The flash control unit 201 is a CPU, for example, and controls the operation of each block of the flash 200 according to an instruction input from the camera control unit 101. Specifically, the flash control unit 201 controls the light emission amount, the light emission time, the light emission angle, and the like. The flash ROM 202 stores operation settings of each block of the flash 200 such as a light emission amount during preliminary light emission and a voltage corresponding to the instructed light emission amount. The light emitting unit 203 emits strobe light at a voltage instructed by the flash control unit 201. The pulse generation unit 204 generates a pulse signal for instructing the light emission amount from the flash 200 (first flash) attached to the digital camera 100 to the second flash installed outside. The pulse signal generated by the pulse generator 204 is a pulse signal conforming to a protocol for optically communicating the first flash and the second flash. The flash control unit 201 of the first flash causes the light emitting unit 203 to emit light with the pulse signal generated by the pulse generating unit 204 and performs optical communication with the second flash. The flash control unit 201 of the second flash controls the light emission amount based on the pulse signal from the flash 200 (first flash) received by the light receiving unit (not shown).

The imaging process of the digital camera of this embodiment having such a configuration will be described with reference to the flowcharts of FIGS.
When there is a user input to the power button of the operation input unit 104, the camera control unit 101 starts control of each block of the digital camera 100. The camera control unit 101 enters the image of the subject that has entered through the optical system 105 and is formed by the imaging unit 106 to the image display unit 111 and starts through display. At this time, the camera control unit 101 determines that the state of the digital camera 100 is in an imaging standby state, and is in a state where it can accept the start of imaging processing.

  FIG. 4 is a flowchart illustrating the contents of the imaging process performed by the camera control unit 101 when the digital camera 100 enters the imaging standby state and receives an input to the operation input unit 104 from the user to perform imaging. In the present embodiment, an imaging process of the digital camera 100 in an environment in which external light, such as under a light line, is affected by flicker will be described.

(Light emission amount determination process 1)
In step S <b> 401, the camera control unit 101 determines whether the release button included in the operation input unit 104 is half pressed by the user. If the release button of the operation input unit 104 is not half-pressed, the camera control unit 101 moves the process to step S411 and sets the FE lock flag stored in the camera ROM 102 to OFF. The camera control unit 101 repeats the process until the release button of the operation input unit 104 is half pressed. Details of the process for turning on the FE lock flag and the FE lock flag will be described later in the light emission amount determination process 2 described later.

  If the release button of the operation input unit 104 is half-pressed in step S401, the camera control unit 101 moves the process to step S402. Note that the camera control unit 101 performs the processing from step S402 to step S407 only while the release button of the operation input unit 104 is in a half-pressed state. When the release button of the operation input unit 104 changes from a half-pressed state to a state where nothing is pressed, the camera control unit 101 forcibly moves the process to S401. In step S402, the camera control unit 101 determines whether the FE lock flag stored in the camera ROM 102 is ON. If the FE lock flag is not ON, the camera control unit 101 copies the process to step S403.

  In step S403, the camera control unit 101 causes the photometry unit 108 to measure the light incident through the optical system 105, and calculates, for example, an aperture value and a shutter speed corresponding to the current photometry value. The camera control unit 101 temporarily stores the calculated aperture value and shutter speed information corresponding to the current photometric value, for example, in the camera ROM 102. In step S404, the camera control unit 101 causes the focusing unit 109 to calculate the position of the focusing lens that focuses on the subject. The camera control unit 101 temporarily stores, for example, in the camera ROM 102, information on the calculated position of the focusing lens. In step S405, the camera control unit 101 reads the aperture value, shutter speed, and focusing lens position information corresponding to the current photometric value calculated in steps S403 and S404 from the camera ROM 102, and sets the optical system 105 in accordance with each information. Control.

  In step S406, the camera control unit 101 determines whether the FE lock button included in the operation input unit 104 is pressed by the user while the release button included in the operation input unit 104 is half pressed. If the user does not input to the FE lock button included in the operation input unit 104, the camera control unit 101 moves the process to step S407. In step S407, the camera control unit 101 determines whether the release button included in the operation input unit 104 has been fully pressed (fully pressed) by the user. If the release button is not fully pressed, the camera control unit 101 returns the process to step S401.

  If the release button included in the operation input unit 104 is fully pressed in step S407, the camera control unit 101 moves the process to step S408, and determines whether the FE lock flag stored in the camera ROM 102 is ON. If the FE lock flag is ON, the camera control unit 101 moves the process to step S410. If the FE lock flag is OFF, the camera control unit 101 moves the process to step S409. In step S409, the camera control unit 101 performs a light emission amount determination process for each of the first flash mounted on the digital camera 100 and the second flash installed outside.

  Here, the light emission amount determination processing performed by the camera control unit 101 to determine the light emission amounts of the first and second flashes will be described in detail with reference to the flowchart of FIG. FIG. 5A is a flowchart of the light emission amount determination process performed by the camera control unit 101 when performing normal imaging (imaging without using the FE lock).

  In step S <b> 501, the camera control unit 101 uses the photometry unit 108 to measure a non-light-emitting subject (first photometry) before performing preliminary light emission of the first flash to obtain a non-light-emission photometric value. The camera control unit 101 stores, in the camera ROM 102, the photometric value of the subject before the first flash preliminary light emission measured by the photometric unit 108 as the photometric value of the subject before the first flash preliminary light emission.

  In step S <b> 502, the camera control unit 101 transmits a preliminary light emission instruction to the flash control unit 201 of the first flash mounted on the digital camera 100. The flash control unit 201 of the first flash uses the preliminary flash emission amount stored in the flash ROM 202 of the first flash in accordance with the preliminary flash instruction received from the camera control unit 101, and sets the preliminary flash emission to the first flash emission unit 203. Make the flash fire. The camera control unit 101 performs photometry on the subject when the first flash is preliminarily emitted by the photometry unit 108 (second photometry), and the obtained pre-emission photometric value is stored in the camera ROM 102 during the first flash pre-emission. Stored as the photometric value of the subject. Note that the preliminary light emission is light emission performed prior to the main light emission indicating light emission at the time of photographing, and is performed in order to calculate the main light emission amount.

  In step S <b> 503, the camera control unit 101 determines the magnitude of the influence of flickering of the power line that is external light on the photometric result that is performed before the preliminary light emission by the first flash. Specifically, the camera control unit 101 obtains a photometric value of the subject before the first flash preliminary light emission stored in the camera ROM 102 and a predetermined value determined as a photometric value capable of ignoring the flicker of the power line that is external light. Compare. The photometric value that can ignore the flicker of the power line that is external light is, for example, a threshold value of the photometric value stored in advance in the camera ROM 102. When the photometric value of the subject before the first flash preliminary light emission is small, that is, when the luminance of the subject environment is low, it is considered that the influence of the light source that generates flicker such as a power line in the environment is small. That is, the luminance of the subject before preliminary light emission with the first flash and the luminance of the subject before preliminary light emission with the second flash have little influence on the photometric value of flicker that changes depending on the timing of light measurement. It can be determined that the difference between the photometric values is small. That is, the luminance of the subject before the preliminary light emission with the first flash and the luminance of the subject before the preliminary light emission with the second flash can be regarded as substantially the same as the reflected light component of the subject due to external light. . For this reason, the camera control unit 101 determines that the subject before the first flash preliminary light emission is equal to or smaller than a predetermined value determined as a photometric value that can ignore the flicker of external light before the second flash preliminary light emission. If it is determined that it is not necessary to meter the subject, the process proceeds to step S505. Note that, for example, a value at which the component of the reflected light of the subject due to the external light is considered to be sufficiently smaller than the component of the reflected light of the subject due to the preliminary light emission is set as the photometric value that can ignore the flicker of the external light.

  In step S503, if the photometric value of the subject before the first flash preliminary light emission is larger than a predetermined value determined as a photometric value that can ignore flicker of external light, the camera control unit 101 causes the photometry unit 108 to send the second flash. Measure the subject when no light is emitted before performing preliminary light emission. The camera control unit 101 stores, in the camera ROM 102, the photometric value of the subject before the second flash preliminary light emission measured by the photometric unit 108 as the photometric value of the subject before the second flash preliminary light emission.

  In step S <b> 505, the camera control unit 101 transmits an instruction for causing the second flash to perform preliminary light emission to the flash control unit 201 of the first flash mounted on the digital camera 100. The flash control unit 201 of the first flash uses the first flash pulse generation unit 204 to instruct the second flash to perform preliminary light emission by optical communication in accordance with the second flash preliminary light emission instruction received from the camera control unit 101. Generate a pulse signal. The flash control unit 201 of the first flash causes the light emitting unit 203 of the first flash to emit light with the pulse signal generated by the pulse generation unit 204 of the first flash. The flash control unit 201 of the second flash receives the preliminary light emission command transmitted from the light emission unit 203 of the first flash through optical communication by the light receiving unit of the second flash. The flash control unit of the second flash causes the second flash light emitting unit 203 to perform preliminary light emission with the amount of preliminary light emission stored in the flash ROM 202 of the second flash according to the received preliminary light emission instruction. The camera control unit 101 measures the subject when the second flash is preliminarily emitted by the photometry unit 108, and stores the obtained photometric value in the camera ROM 102 as the photometric value of the subject at the time of the second flash preliminary emission.

  In step S506, the camera control unit 101 performs preliminary light emission of the first flash from the photometric value of the subject before the first flash preliminary light emission stored in the camera ROM 102 and the photometric value of the subject during the first flash preliminary light emission. Information on the reflected light of the subject is obtained. Specifically, the camera control unit 101 subtracts the photometric value of the subject before the first flash preliminary light emission from the photometric value of the subject at the time of the first flash preliminary light emission for each of the multi-divided areas where the photometric unit 108 performs photometry. To do. The camera control unit 101 stores the difference between the photometric values of each area obtained by the subtraction in the camera ROM 102 as information on the reflected light of the subject by the preliminary light emission of the first flash.

  In step S <b> 507, the camera control unit 101 obtains information on the reflected light of the subject by preliminary light emission of the second flash from the information on the photometric value of the subject stored in the camera ROM 102. At this time, the calculation method of the reflected light of the subject by the preliminary light emission of the second flash varies depending on the photometric value of the subject before the first flash preliminary light emission in step S503. Specifically, when the photometric value of the subject before preliminary light emission of the first flash is less than or equal to a predetermined value determined as a photometric value that can ignore flicker of external light, the subject of the subject in the second flash preliminary light emission The photometric value of the subject before the first flash preliminary light emission is subtracted from the photometric value. That is, the main light emission amounts of the first flash and the second flash are calculated using the same value as the photometry value at the time of non-light emission. Further, when the photometric value of the subject before the preliminary flash emission of the first flash is larger than a predetermined value set as a photometric value that can ignore the flicker of the external light, from the photometric value of the subject at the second flash preliminary emission, The photometric value of the subject before the second flash preliminary light emission is subtracted. The camera control unit 101 stores the difference between the photometric values of each area obtained by the subtraction in the camera ROM 102 as information on the reflected light of the subject by the preliminary light emission of the second flash. It should be noted that when the difference between the photometric values of the respective areas is obtained in steps S506 and S507, if the photometric time length of the photometric unit 108 differs between the photometry before the preliminary light emission and the photometry at the preliminary light emission, Correction is made so as to obtain the difference between the photometric values of each area. This is because if the metering time length differs between the metering before the pre-flash and the metering at the pre-flash, even if the metering value before the pre-flash is subtracted from the metering value during the pre-flash, This is because it is not a component of reflected light. Therefore, for example, if the length of the photometry time before the preliminary light emission is twice the length of the photometry time at the time of the preliminary light emission, the subtraction is performed after correcting the photometric value before the preliminary light emission to ½ times. To.

In step S <b> 508, the camera control unit 101 calculates the first flash and the reflected light of the subject by preliminary light emission of the first flash and the information of reflected light of the subject by preliminary light emission of the second flash stored in the camera ROM 102. The amount of main light emission of the second flash is determined. For example, the main light emission amount of the first flash is obtained by weighting and averaging the reflected light of the subject by the preliminary light emission of the first flash in each area, and the light amount ratio C_ratio of light emission in the exposure processing of the first flash and the second flash. Is calculated and determined by a known calculation method. The calculation of the light emission amount is obtained as follows, for example, as a ratio G between the light emission amount of the preliminary light emission and the light amount in the exposure process.
G = target-ΔF + C_ratio
Here, the target is an exposure amount determined according to an aperture value used at the time of shooting, a shutter time, and an exposure sensitivity. The light emission ratio C_ratio of light emission in the exposure process can be set to an arbitrary ratio by the user. The camera control unit 101 sets the light emission amounts of the first flash and the second flash so that the light amount ratio becomes C_ratio when the light emission amount of the appropriate exposure is obtained when the first flash and the second flash are combined. decide.

  The camera control unit 101 transmits the determined main light emission amounts of the first flash and the second flash to the flash control unit 201 of the first flash. Also, the flash control unit 201 of the first flash generates a pulse signal by the pulse generation unit 204 of the first flash based on the received information on the light emission amount of the second flash, and the light emission unit 203 of the first flash can be obtained. The light is emitted according to the pulse signal. The flash control unit 201 of the second flash receives the information on the light emission amount of the second flash transmitted from the first flash by optical communication at the receiving unit of the second flash.

  In this way, the main light emission amounts of the first flash and the second flash are determined and transmitted to the first flash and the second flash, respectively. The camera control unit 101 performs imaging by causing the first flash and the second flash to emit light according to the main light emission amount determined in the exposure processing in step S410.

  In the present embodiment, it is assumed that the camera control unit 101 uses the photometric value of the subject before the first flash preliminary light emission to determine whether to measure the subject before the second flash preliminary light emission in step S503. did. However, the photometric value at which the camera control unit 101 determines whether or not to measure the subject before preliminary light emission of the second flash in step S503 is measured in step S403 before the release button is fully pressed in step S407, for example. The photometric value of the subject may be used.

(Light emission amount determination process 2)
If the user inputs to the FE lock button provided in the operation input unit 104 in step S406, the camera control unit 101 moves the process to step S412. The FE lock button is an input interface that can be used to calculate the main flash amounts of the first flash and the second flash in advance without imaging, receives input from the user (calculation instruction reception), and controls the camera. The unit 101 starts the main light emission amount determination process. The user can determine the light emission amount of each flash in advance by pressing the FE lock button while the subject is captured at the center (frame center) on the image display unit 111, and the framing is performed in that state. It is possible to change the image. As a result, the camera control unit 101 can record an image in a state where an appropriate flash is emitted to a subject that is not in the center of the frame. If the camera control unit 101 determines in step S406 that the FE lock button included in the operation input unit 104 has been pressed by the user, the process proceeds to step S412. If it is not determined that the FE lock button has been pressed, the process proceeds to step S407.

  In step S <b> 412, the camera control unit 101 turns on the FE lock flag stored in the camera ROM 102. The FE lock flag indicates that the light emission amounts of the first and second flashes are determined in advance by a user input to the FE lock button, and the FE lock flag is turned off after imaging is completed. And Also, when it is determined that the release button of the operation input unit 104 is half-pressed between step S401 and step S407, the camera control unit 101 moves the process to step S411 and sets the FE lock flag to OFF. It shall be.

  Note that the timing for turning off the FE lock flag may be different from the above-described flowchart. For example, the FE lock flag may be turned ON while the FE lock button is pressed, and the FE lock flag may be turned OFF when the FE lock button is released. Alternatively, the FE lock flag may be turned off when the shooting mode is changed by a user input to the operation input unit 104 or when a menu screen is displayed. Further, when the FE lock button is pressed while the FE lock flag is ON, the light emission amount determination process described later may be performed again to update the main light emission amount. In this case, the camera control unit 101 may move the process to S406 when the FE lock flag is ON in step S402.

Next, in step S413, the camera control unit 101 performs a light emission amount determination process to determine the light emission amount for each of the first flash mounted on the digital camera 100 and the second flash installed outside. .
Here, the light emission amount determination processing performed by the camera control unit 101 to determine the light emission amounts of the first and second flashes will be described in detail with reference to the flowchart of FIG. FIG. 5B is a flowchart of the light emission amount determination process performed by the camera control unit 101 when imaging is performed using the FE lock. In the description of the flowchart of FIG. 5B, the steps for performing the same processing as in FIG. 5A are denoted by the same reference numerals and description thereof is omitted, and the light emission amount determination processing when this FE lock is used. I'll just explain the characteristic steps.

  In step S502, after the acquisition of the photometric value of the subject before the first flash preliminary light emission and the photometric value of the subject during the first flash preliminary light emission are completed, the camera control unit 101 waits for processing (step S509). Specifically, the camera control unit 101 determines a time for waiting for processing according to the photometric value of the subject before the first flash preliminary light emission stored in the camera ROM 102. As described above, when the compression-type photometric sensor is used and the luminance of the environment of the subject is low, immediately after measuring the photometric value of the subject at the time of the first flash preliminary light emission, the subject before the preliminary light emission of the second flash If the light is metered, the metered value will be measured brighter than it should be. This is because when the subject at the time of preliminary light emission is measured and then subject's environment is measured, the compression-type photometric sensor provided in the photometry unit 108 has received the preliminary light emission from the high luminance (bright) that received the preliminary light emission. This is because it takes time for the output voltage to stabilize at a low luminance. That is, depending on the photometric value of the subject before the first flash preliminary light emission, that is, the photometric value of the subject environment, the camera control unit 101 includes a photometric sensor included in the photometric unit 108 to measure the subject before the second flash preliminary light emission. It is necessary to wait until the output voltage value becomes stable. That is, the time proportional to the difference between the photometric value at the time of the first flash preliminary light emission and the photometric value of the environment of the subject (non-light-emitting photometric value) until the value of the output voltage of the photometric sensor provided in the photometric unit 108 is stabilized. Cost. Since the amount of light emitted during the preliminary light emission of the first flash is preset in the camera ROM 102 of the first flash, the standby time until the value of the output voltage of the photometric sensor provided in the photometric unit 108 becomes stable depends on the environment of the subject. A length that is inversely proportional to the photometric value may be set. In other words, the smaller the non-light-emission photometric value before preliminary light emission of the first flash, the longer the interval between the first flash preliminary light emission and the second flash pre-light emission measurement. The camera control unit 101, for example, measures the subject at the time of the preliminary flash emission of the first flash, and then performs processing as shown in the following table according to the photometric value (Bv_r) of the subject before the first flash preliminary emission stored in the camera ROM 102. Can be kept waiting.

  After the standby time as described above elapses, the process proceeds to step S504, but the process from step S504 to step S508 is the same as that in FIG. Note that the light emission amount determination process 2 is effective when there is no problem even if time is required for the light emission amount determination process, such as when imaging is performed in advance using an FE lock, not during imaging.

When imaging using the FE lock, after determining the light emission amounts of the first and second flashes in this way, the camera control unit 101 determines that the release button provided in the operation input unit 104 is all set by the user in step S413. Wait until it is pressed. When the release button is fully pressed by the user, the camera control unit 101 performs imaging by causing the first flash and the second flash to emit light according to the determined light emission amount in the exposure processing of S409.
Similar to the light emission amount determination process 1, the process of step S503 is performed after step S502, and the non-flashing before the second flash performs preliminary light emission according to the photometry result performed before the preliminary light emission by the first flash. Photometry during light emission may not be performed.

  As described above, the imaging device according to the present embodiment performs the first flash and the second flash when performing flash photography using the first flash mounted on the imaging device and the second flash installed outside. In order to determine the amount of light emission, the following processing is performed. If the photometric value of the subject measured before the first flash preliminarily emits light is equal to or less than a predetermined value that is determined in advance as a photometric value that can ignore flicker of the power line that is external light, the second flash preliminarily emits light Do not meter the subject before shooting. Then, using the photometric value of the subject during the first flash preliminary light emission, the photometric value of the subject during the second flash preliminary light emission, and the photometric value of the subject before the first flash preliminary light emission, the first and second flashes are used. Calculate the amount of light emission. In addition, when the photometric value of the subject measured before the first flash preliminarily emits is larger than a predetermined value set in advance as a photometric value that can ignore flicker of the power line that is external light, the second flash Measure the subject before firing. Then, the light emission amounts of the first and second flashes are calculated using the photometric value of the subject before the first and second flash preliminary flashes and the photometric value of the subject at the time of the first and second flash preliminary flashes.

  In addition, in the imaging apparatus of the present embodiment, when the light emission amounts of the first and second flashes are calculated using the FE lock without imaging, the photometric sensor is used after measuring the subject at the time of preliminary light emission of the first flash. Wait until processing stabilizes. Specifically, the waiting time until the output of the photometric sensor is stabilized is determined by the photometric value of the subject before the first flash preliminary light emission. After waiting for processing, the subject is metered before preliminary light emission of the second flash and during preliminary light emission, the photometric value of the subject before the first and second flash preliminary light emission, and the photometry of the subject during the first and second flash preliminary light emission. The light emission amounts of the first and second flashes are calculated using the values.

  In the present embodiment, the processing for determining the light emission amounts of the two flashes by performing preliminary light emission when performing flash photography using the two flashes has been described. However, the present invention is not limited to two flashes, but can be applied to flash photography using three or more flashes. In such a case, the following processing may be performed when preliminary flashing is sequentially performed on a plurality of flashes. If the photometric value of the subject measured before the first flash is preliminarily emitted is equal to or smaller than the photometric value determined in advance so that the flicker of the power line that is outside light can be ignored, the second and subsequent flashes The subject is not metered before pre-flash. Then, for each of the plurality of flashes, each of the flashes is measured using the photometric value of the subject measured by performing preliminary light emission, and the photometric value of the subject measured before the first flash performs preliminary light emission. Determine the flash output.

Further, in the present embodiment, the case where photographing is performed using a plurality of different illumination devices (first flash and second flash) has been described. However, a plurality of main light emission amounts are continuously obtained using a single illumination device. The present invention can also be applied to cases where computation is performed and imaging is performed. For example, when performing continuous shooting with light emission, light is emitted continuously with a single lighting device, and the amount of each light emission is calculated using the photometric value at the time of non-light emission and the photometric value at the time of preliminary light emission each time. The present invention can also be applied to cases where computation is performed. That is, in the case of performing photometry during non-light emission in order to calculate the second main light emission amount immediately after the first main light emission, the following processing may be performed. If the photometric value at the time of non-light emission used for the calculation of the first main light emission amount is equal to or less than a predetermined value determined as a photometry value that can ignore flicker that is external light, the non-light emission used for the calculation of the main light emission amount for the second and subsequent times The photometric value at the time may be the photometric value at the time of non-light emission used for the first calculation of the main light emission amount.
In addition, when imaging is performed by sequentially determining the light emission amounts of a plurality of flashes using the FE lock in advance, the subject is measured at the time of preliminary light emission of the previous flash for the second and subsequent flashes, and then the photometry is performed. What is necessary is just to make a process wait until the output of a sensor is stabilized.

  In the present embodiment, the case where a flash mounted on the imaging device and a flash installed outside without being mounted are described. However, none of the plurality of flashes is mounted on the imaging device. Also good. In that case, a light emission instruction or the like to each flash may be performed using a communication unit provided in the imaging device or a communication device detachably attached to the imaging device. In the case of an imaging device with a built-in strobe, a built-in strobe may be used instead of the flash attached to the imaging device in the present embodiment.

(Other embodiments)
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.

Claims (5)

An imaging device capable of photographing using an illumination device that emits light toward a subject,
Imaging means for imaging a subject;
Metering means for metering the subject;
Based on a non-light-emission photometric value obtained by the photometry means when the illuminating device is not lit, and a preliminary light-emission photometric value obtained during the preliminary luminescence performed prior to the main luminescence of the illuminating device, Calculating means for calculating the main light emission amount of the apparatus,
When the calculation unit continuously calculates a plurality of main flash amounts, if the non-light-emission photometric value obtained by the photometry unit is less than or equal to a predetermined value before the first main flash amount calculation, Calculating the respective main light emission amounts based on the non-light emission photometric values used for calculating the main light emission amounts and the preliminary light emission photometric values obtained during the preliminary light emission performed prior to each main light emission. An imaging device that is characterized.   When the calculation means continuously calculates a plurality of main light emission amounts, if the non-light emission photometric value used for the calculation of the first main light emission amount is equal to or less than a predetermined value, The imaging apparatus according to claim 1, wherein each main light emission amount is calculated based on the preliminary light-emission photometric value obtained during the preliminary light emission performed prior to the main light emission. A calculation instruction receiving means for receiving a calculation instruction for calculating a main light emission amount of the lighting device without imaging by the imaging means;
When the light metering means calculates a plurality of main light emission amounts continuously according to the calculation instruction received by the calculation instruction reception means, the non-light emission time obtained by the photometry means before the calculation of the first main light emission amount 3. The image pickup apparatus according to claim 1, wherein the smaller the photometric value, the longer the interval between the preliminary light emission by the illumination device and the next time the non-light-emission photometry is performed.   The imaging apparatus according to claim 1, wherein the predetermined value is a value determined in advance as a photometric value that can ignore flicker that is external light. An imaging apparatus control method comprising: an imaging unit that images a subject; and a photometric unit that performs photometry of the subject, and capable of shooting using an illumination device that emits light toward the subject,
Based on a non-light-emission photometric value obtained by the photometry means when the illuminating device is not lit, and a preliminary light-emission photometric value obtained during the preliminary luminescence performed prior to the main luminescence of the illuminating device, A calculation step of calculating a main light emission amount of the apparatus,
In the calculation step, when a plurality of main light emission amounts are calculated continuously, the first light emission amount obtained by the photometry means before the first main light emission amount calculation is less than or equal to a predetermined value. Calculating the respective main light emission amounts based on the non-light emission photometric values used for calculating the main light emission amounts and the preliminary light emission photometric values obtained during the preliminary light emission performed prior to each main light emission. A control method for an imaging apparatus.

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