JP4974862B2 - Imaging apparatus and control method thereof - Google Patents

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly to an imaging apparatus having a plurality of photometry methods.

  As an imaging device for recording a subject image, a so-called digital camera is known in which a subject image is photoelectrically converted and recorded after being subjected to predetermined processing. In a digital camera, the same means and method as those of a camera using a conventional silver salt film are used as a photometric means and control method for determining the exposure value.

  Therefore, an invention relating to a method for controlling an image pickup apparatus having an automatic exposure function and capable of continuous shooting has been proposed.

In this method, when the subject brightness changes abruptly during continuous shooting, for example, a moving subject enters the shade from the sun by taking a picture using a preset exposure value stored in advance. It corresponds to exposure control in a scene (see Patent Document 1).
JP-A-8-240834

  However, in the method described in Patent Document 1, the following problems may occur when shooting is continuously performed when spot photometry is used where the photometry area is narrower than the shooting screen.

  For example, when there is a change in the brightness of a region that is subject to spot metering between captured images due to the movement of a subject or the like, exposure control is performed with a preset exposure value.

  However, there is a problem that the spot metering function of performing the metering so that the exposure of the target area is optimized is not utilized.

To achieve the above object, an imaging apparatus according to the present invention performs photometry, and the first photometric data obtained from the first metering area, broadly the first metering area than the first metering area A first photometric unit that can output second photometric data obtained from a second photometric region including the first photometric data, and a first difference that is a difference between the two first photometric data obtained successively. Calculating means, second calculating means for calculating a second difference that is a difference between two pieces of second photometric data obtained successively, and an absolute value of the first difference being a first predetermined value In the above case, there is provided selection means for selecting photometric data used for exposure control based on the second difference .

In order to achieve the above object, a control method of an imaging apparatus according to the present invention performs photometry, and the first photometric data obtained from the first metering area wider the than the first metering area A method for controlling an imaging apparatus having a photometric means capable of outputting second photometric data obtained from a second photometric area including the first photometric area, wherein the two first photometry are obtained continuously. A first calculation step for calculating a first difference that is a difference between data; a second calculation step for calculating a second difference that is a difference between two second photometric data obtained successively; A selection step of selecting photometric data used for exposure control based on the second difference when the absolute value of the first difference is equal to or greater than a first predetermined value .

According to the present invention, it is possible to perform exposure control such as the Utsushitai is suitable exposure.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings.
The embodiment described below is an example for realizing the present invention, and should be appropriately modified or changed according to the configuration and various conditions of the apparatus to which the present invention is applied. It is not limited to the embodiment.

<First Embodiment>
A first embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of an imaging apparatus according to the first embodiment.

  In the figure, 1 is a lens, 2 is a movable main mirror, 3 is a shutter as a light-shielding curtain, 4 is a focusing plate, and 5 is a pentaprism that reflects light reflected by the mirror in the vertical direction twice to guide the eyepiece. It is.

  Reference numeral 6 denotes an image pickup device having a photoelectric conversion function such as a CCD sensor or a CMOS sensor that photoelectrically converts a subject image formed by the photographing optical system.

  Reference numeral 7 denotes a signal processing unit that performs predetermined processing such as A / D conversion on the output of the image sensor 6 and generates an image signal. Reference numeral 8 denotes various controls of the imaging apparatus including automatic focusing and exposure control. It is a control part to perform.

9 is a photometric sensor (photometric means) capable of measuring the brightness of the object field and outputting the result, 10 is a memory for recording a photographed image that can be attached to and detached from the image pickup apparatus body, and 11 is provided on the back of the image pickup apparatus. It is a display part comprised with the liquid crystal monitor etc. which display an image etc.
Reference numeral 12 denotes a setting member that can set the photometric mode of the image pickup apparatus, and 13 denotes a release button that instructs the start of shooting.

  A subject image (not shown) is reflected by the main mirror 2 through the lens 1 and is formed on the focus plate 4 at a position conjugate with the image sensor 6.

  The subject image on the focus plate 4 is observed by the photographer through the pentaprism 5, and part of the light flux of the subject image diffused by the focus plate 4 is incident on the photometric sensor 9 to measure the subject light. .

FIG. 2 is a diagram showing a first photometry area and a second photometry area in the present embodiment.
In FIG. 2, (a) is a spot area as a first photometry area that measures the area of about 5% of the central area of the imaging area, and (b) includes a spot photometry area, which is a wider imaging area. This is a partial photometry area as a second photometry area that measures the area of about 15% of the center.

The photometric sensor 9 outputs two types of photometric data, the first photometric data obtained from the first photometric area and the second photometric data obtained from the second photometric area.
Then, the first photometry data and the second photometry data are input to the control unit 8.

  When the spot metering mode is selected as the metering mode by the setting member 12 and shooting is performed in the single shooting mode, or when the spot metering mode is selected and shooting of the first shot in the continuous shooting mode is performed, the first Photometric data is output to the control unit 8.

  Then, the control unit 8 determines a shutter speed, an aperture value, and a signal amplification factor based on the first photometric data.

  When the continuous shooting mode is selected as the shooting mode by the setting member 12, a series of shooting sequences are executed when the release button 13 is pressed down. If the release button 13 is continuously depressed after the shooting sequence is executed, the shooting sequence for the next bag is continuously started.

  In the present embodiment, the photometry mode and the shooting mode are selected by the setting member 12, but the setting means is not limited to this, and a setting menu is displayed on the display unit and selected from there. You may make it do. Further, the setting member 12 may be handled as a general-purpose setting member capable of selecting a shooting function other than the photometry mode and the shooting mode.

  In addition, the photometry mode and the photographing mode are selected using a common member (setting member 12), but may be selected using different members.

When the spot photometry mode is selected and the second and subsequent shots are taken in the continuous shooting mode, the control unit 8 determines the exposure value using the first photometry data and the second photometry data. .
The above operation is repeated until the release button 13 is released.

During the photographing sequence, the diaphragm (not shown) provided in the lens 1 is controlled to have a predetermined aperture value in accordance with a control signal from the control unit 8, and the main mirror 2 is retracted in the direction of the focus plate 4, The shutter 3 opens and closes at the shutter speed.
The subject image formed on the image sensor 6 is photoelectrically converted and read as an electrical signal.

  The image signal read from the image sensor 6 is subjected to predetermined processing by the signal processing unit 7 and then recorded in the memory 13 by the control unit 8.

  FIG. 3 is a flowchart showing the operation of the imaging sequence in the first embodiment. The operation will be described below with reference to the drawings.

When a power supply (not shown) of the image pickup apparatus is turned on, the image pickup standby state is set. When the release button 13 is pressed, the image pickup apparatus starts processing from step 100.
In step S100, the exposure value is determined according to the photometry mode set by the setting member 12.
In step S101, the main mirror 2 is retracted from the optical path.
In step S102, the aperture of the lens 1 is set according to the exposure value determined in step S100.
In step S103, the accumulation operation of the image sensor 7 is started.
In step S104, the shutter 3 is opened in conjunction with the start of the accumulation operation of the image sensor 7.
In step S105, it is determined whether or not a predetermined time has elapsed. If it is determined that the predetermined time has elapsed, the control unit 8 advances the process to step S106. Here, the predetermined time is calculated based on the shutter speed calculated by the control unit 8.
In step S106, the shutter 3 is closed.
In step S107, the main mirror 2 returns to the optical path.
In step S108, a photographing signal is read from the image sensor 6, and when the reading is completed, the control unit 8 advances the process to step S109.
In step S109, the control unit 8 determines the shooting mode. If it is determined that the mode is the single shooting mode, the control unit 8 ends the shooting operation.
If the control unit 8 determines in step S109 that the shooting mode is the continuous shooting mode, the process proceeds to step S110.
In step S110, the control unit 8 determines whether or not the release button 13 is pressed even when the reading of the image signal is completed. If the release button 13 is not pressed, the photographing operation is terminated.

  If the control unit 8 determines in step S110 that the release button 13 has been pressed even after the image signal has been read, the process returns to step S100 and the second image is taken.

  Hereinafter, the shooting sequence from S100 to S110 is repeated until the release button 13 is released or the shooting cannot be continued due to other factors such as the capacity of the memory 13 being insufficient.

  FIG. 4 is a flowchart showing a detailed operation flow of the exposure value determination process in step S100 in FIG. The operation will be described below with reference to the drawings.

  When the exposure value determination process in step S100 of FIG. 3 is started, the process from step S201 is started.

  In step S <b> 200, the photometric element 9 outputs the first photometric data that is the photometric data of the spot photometric area and the second photometric data that is the photometric data of the partial photometric area to the control unit 8.

  In step S201, if the shooting mode is the single shooting mode or the first shot in the continuous shooting mode, the control unit 8 advances the process to step S207 to obtain the photometric data of the currently set photometric area. Based on the exposure value.

  In step S201, the control unit 8 advances the process to step S202 when the shooting mode is the second shooting mode in the continuous shooting mode.

  In step S202, the control unit 8 compares (first comparison) the first photometric data of the current photographing basket with the first photometric data of the image photographed one previous photograph, and the difference (first comparison). Difference) is calculated.

  In step S203, it is determined whether or not the absolute value of the difference calculated in step S202 is greater than or equal to a predetermined value. Here, it is assumed that the set predetermined value is set to a value that can determine whether the subject is in the spot photometry area.

  If it is determined in step S203 that the absolute value of the difference calculated in step S202 is smaller than the predetermined value, the control unit 8 advances the process to step S207, and based on the photometric data of the currently set photometric area. To determine the exposure value. This is because it is considered that the subject can be captured in the currently set photometric area because the difference between the photometric data and the most recently captured image is smaller than a predetermined value.

  If it is determined in step S203 that the absolute value of the difference calculated in step S202 is greater than or equal to a predetermined value, the control unit 8 advances the process to step S204.

  In step S204, the second photometric data of the current shooting rod is compared with the second photometric data of the image shot immediately before (second comparison), and a difference (second difference) is calculated. .

  In step S205, it is determined whether or not the absolute value of the difference calculated in step S204 is equal to or less than a predetermined value. Here, it is assumed that the predetermined value as the second set value that has been set is set to a value that can determine whether or not the subject is in the partial photometric photometry region.

  If it is determined in step S205 that the absolute value of the difference calculated in step S204 is larger than the predetermined value, the control unit 8 advances the process to step S207, and based on the photometric data of the currently set photometric area. To determine the exposure value.

  This is because the difference in the first photometric data between the front and rear photographing rods is large, and the difference between the second photometric data in the front and rear photographing rods is also large. This is because it may have been dark. In other words, it can be considered that the subject itself has not moved out of the photometry area, but has just followed the photometry area, only by changing the first and second photometry data due to the influence of ambient light. The exposure value is determined based on the photometric data of the photometric area.

  If it is determined in step S205 that the absolute value of the difference calculated in step S204 is equal to or smaller than a predetermined value, the control unit 8 advances the process to step S206.

  In step S206, the exposure value is determined by adding the difference calculated in step S204 to the first photometric data in the previous photographing basket. By doing so, it becomes possible to suitably control the exposure of the subject that is no longer in the first photometric flow area but can be captured in the second area.

  In this embodiment, the configuration of a single-lens reflex camera that cannot perform live view is assumed, but the present invention is not limited to this.

  It goes without saying that the same processing can be performed even in single-lens digital cameras, compact digital cameras, video cameras, etc. capable of live view when the spot metering mode is set when shooting in continuous shooting mode. .

  At that time, the image sensor also serves as a photometric sensor, and therefore, the output of the image sensor 6 is also sent to the control unit, and control for calculating the first and second photometric data is performed.

  As described above, according to the present embodiment, when performing photometry by spot metering during shooting in continuous shooting mode, subject movement determination is performed by taking into account the photometry value of a partial photometry area wider than the target area of spot metering. Yes. Therefore, it is possible to perform exposure control with higher accuracy than performing exposure control only on the spot photometry area.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. In addition, about the structure of an imaging device, the structure similar to 1st Embodiment is abbreviate | omitted description.

  In the first embodiment, two photometric areas are set by one photometric sensor, and the first photometric data and the second photometric data are output. However, in the present embodiment, the photometric sensor 14 is newly provided. Different.

FIG. 5 shows a configuration diagram of an imaging apparatus according to the second embodiment.
In FIG. 5, reference numeral 14 denotes a first photometric sensor, which performs photometry in the spot photometry mode and outputs a photometric value. Reference numeral 15 denotes a second photometric sensor, which performs photometry in a partial photometry mode in which photometry is performed in an imaging region wider than the spot photometry region, and outputs a photometric value.
Other configurations and the processing flow are the same as those in the first embodiment, and are therefore omitted.

  As described above, in the first embodiment, two photometric data are output by one photometric sensor. However, in this embodiment, different photometric areas are set by the two photometric sensors to obtain photometric data. The same effects as those of the first embodiment can be obtained.

<Third Embodiment>
Hereinafter, a third embodiment of the present invention will be described. In addition, about the structure of an imaging device, description is abbreviate | omitted about the structure similar to 1st and 2nd embodiment.

  In the first and second embodiments, the processing in the case where the spot metering mode is set at the time of shooting in the continuous shooting mode has been described, but in the present embodiment, the display unit 11 sequentially displays as a live view image. A process for an image to be performed will be described.

  The present embodiment has a live view function for displaying image signals sequentially read from the image sensor on the display unit 11, and when the spot photometry mode is set, the first implementation described above. Exposure control processing is performed by selecting a photometric value similar to that of the form.

  Although the first and second embodiments have been described on the assumption of a single-lens digital camera configuration, the photometric sensor is provided. However, in a single-lens digital camera, a compact digital camera, and a video camera capable of live view, imaging is performed. The light is measured with the element.

  Then, the output of the image sensor is also sent to the control unit, and the first and second photometric data are calculated.

  FIG. 6 is a flowchart showing a detailed operation flow of the exposure value determination process in the present embodiment. The operation will be described below with reference to the drawings.

  In step S200, the photometric element 9 outputs the first photometric data that is the photometric data of the spot photometric area and the second photometric data that is the photometric data of the partial photometric area to the control unit 8.

  In step S301, the control unit 8 determines whether or not the live view function is ON.

  If the control unit 8 determines in step S301 that the live view function is not turned on, the process proceeds to step S201, and the same process as in the first embodiment is performed.

  If the control unit 8 determines in step S301 that the live view function is ON, the process proceeds to step S202, and the same process as in the first embodiment is performed.

  In the first embodiment, the current captured image in the continuous shooting mode is compared with the most recently captured image. However, in the present embodiment, the currently displayed image is currently displayed on the display unit 11. The image that has been displayed is compared with the most recently displayed image.

  As described above, according to the present embodiment, when live view is functioning, it is possible to display a good image with little flicker even if spot metering is performed.

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 1st photometry area | region and 2nd photometry area | region of this invention. It is a flowchart which shows the operation | movement of the imaging | photography sequence in the 1st Embodiment of this invention. It is the flowchart which showed the detailed operation | movement flow of the exposure value determination process in the 1st Embodiment of this invention. It is a block diagram which shows the structure of the imaging device which concerns on the 2nd Embodiment of this invention. It is the flowchart which showed the detailed operation | movement flow of the exposure value determination process in the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens 2 Main mirror 3 Shutter 4 Focus plate 5 Penta prism 6 Image sensor 7 Signal processing part 8 Control part 9 Photometric sensor 10 Memory 11 Display part 12 Setting member 13 Release button 14 1st photometric sensor 15 2nd photometric sensor

Claims (9)

First photometric data obtained by performing photometry and obtained from the first photometric area, and second photometric data obtained from a second photometric area wider than the first photometric area and including the first photometric area Photometric means capable of outputting
First calculating means for calculating a first difference which is a difference between two first photometric data obtained in succession;
Second calculating means for calculating a second difference which is a difference between two pieces of second photometric data obtained in succession;
An imaging apparatus comprising: selection means for selecting photometric data used for exposure control based on the second difference when the absolute value of the first difference is equal to or greater than a first predetermined value. When the absolute value of the first difference is equal to or larger than the first predetermined value and the absolute value of the second difference is equal to or smaller than a second predetermined value, the selection unit is configured to select the first photometric data. The first photometric data is selected when the second photometric data is selected and the absolute value of the second difference is greater than a second predetermined value. Imaging device. When the absolute value of the first difference is equal to or greater than the first predetermined value and the absolute value of the second difference is equal to or less than a second predetermined value, the selection means When the first photometric data obtained earlier is selected and the absolute value of the second difference is greater than a second predetermined value, the two first photometric data obtained in succession are selected. The imaging device according to claim 2, wherein the one obtained later is selected. Having setting means for setting the metering mode;
If the photometric mode in which the first photometric area is set as a photometric object is set by the setting means, and the absolute value of the first difference is equal to or greater than a first predetermined value, the selection means 4. The imaging apparatus according to claim 1, wherein photometric data used for exposure control is selected based on the difference. The selection means selects photometric data used for exposure control based on the second difference when the absolute value of the first difference is not less than a first predetermined value during continuous shooting. The imaging device according to any one of claims 1 to 4. Display means for sequentially displaying images based on image data obtained by imaging by the imaging means;
The selection means is used for exposure control based on the second difference when the absolute value of the first difference is greater than or equal to a first predetermined value in a state where the image is sequentially displayed on the display means. 5. The imaging device according to claim 1, wherein photometric data is selected. When the absolute value of the first difference is smaller than a first predetermined value, the selection unit selects the one obtained later among the two first photometric data obtained successively. The imaging device according to any one of claims 1 to 6. 8. The light metering device according to claim 1, wherein the light metering unit includes a light metering sensor whose photometric target is the first photometric region and a photometric sensor whose photometric target is the second photometric region. The imaging device described in 1. First photometric data obtained by performing photometry and obtained from the first photometric area, and second photometric data obtained from a second photometric area wider than the first photometric area and including the first photometric area A method of controlling an imaging apparatus having a photometric means capable of outputting
A first calculation step of calculating a first difference that is a difference between two first photometric data obtained in succession;
A second calculation step of calculating a second difference which is a difference between the two second photometric data obtained in succession;
And a selection step of selecting photometric data used for exposure control based on the second difference when the absolute value of the first difference is greater than or equal to a first predetermined value. Method.

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