JP2013057756A - Photographing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographing apparatus capable of accurately obtaining an amount of light in main light emission.SOLUTION: A photographing apparatus 1 is provided that comprises: a flash light emitting part 17 capable of multiple times of preliminary light emissions; a photometric part 15 having a light receiving element 15C which includes a plurality of pixels 15c receiving light of the preliminary light emissions to accumulate charges according to an amount of light received, and outputting a photometric signal according to the accumulated charges; and a calculating part 30 for calculating a main light emission amount of the flash light emitting part 17 by using the photometric signal outputted from the photometric part 15. In the photographing apparatus 1, the plurality of pixels 15c are two-dimensionally arrayed, and the pixels 15c arranged along different lines among the two-dimensionally arrayed pixels are selected for every preliminary light emission to accumulate the charges.

Description

  The present invention relates to a photographing apparatus.

  In recent years, a CMOS (Complementary Metal Oxide Semiconductor) sensor is often used as a light receiving sensor of an imaging apparatus. In the case of a CMOS sensor, light is generally received by a rolling shutter system. In the rolling shutter system, the accumulation start timing is different for all readout lines. Therefore, in the case of the rolling shutter system, if the number of read lines is large, the time from the start of accumulation of the first read line to the start of accumulation of the last read line becomes longer. Therefore, there is a possibility that the preliminary light emission starts before all the readout lines start accumulation. For this reason, there is a technique in which the readout lines are thinned out (see, for example, Patent Document 1).

Japanese Patent Laying-Open No. 2005-347928

  However, when the readout line is thinned out, the amount of information of the subject to be obtained is reduced, and an appropriate light emission amount of the main light emission cannot be obtained.

  The subject of this invention is providing the imaging device which can obtain | require the light quantity of this light emission correctly.

  The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.

The invention described in claim 1 includes a flash light emitting portion (17) capable of performing preliminary light emission a plurality of times, and a plurality of pixels (15c) that receive the light of the preliminary light emission and accumulate charges corresponding to the amount of received light. A photometric unit (15) having a light receiving element (15C) having an output and outputting a photometric signal corresponding to the accumulated charge; and using the photometric signal output from the photometric unit (15), the flash light emitting unit (17) A calculation unit (30) for calculating a main light emission amount, wherein the plurality of pixels (15c) are two-dimensionally arranged, and for each preliminary light emission, out of the two-dimensionally arranged pixels (15c) The imaging device (1) is characterized in that the pixels (15c) arranged along different lines are selected to accumulate charges.
The invention described in claim 2 is the photographing apparatus (1) according to claim 1, characterized in that there are a plurality of lines of the pixels (15c) selected in one preliminary light emission. This is a photographing apparatus (1).
A third aspect of the present invention is the imaging apparatus (1) according to the first or second aspect, wherein the charge accumulation start timing in the pixel (15c) is different for all lines. Is a photographing apparatus (1).
According to a fourth aspect of the present invention, there is provided the photographing apparatus (1) according to any one of the first to third aspects, wherein a scene determining unit (30) for determining a shooting scene and the scene determining unit (30) And a preliminary light emission number determination unit (30) for determining the number of times of preliminary light emission according to the scene determination result of (1).
According to a fifth aspect of the present invention, there is provided the photographing apparatus (1) according to any one of the first to fourth aspects, wherein a scene determining unit (30) for determining a shooting scene and the scene determining unit (30). And a line number determination unit (30) for determining the total number of the lines selected in the plurality of preliminary light emission operations according to the scene determination result of (2). It is.
A sixth aspect of the present invention is the imaging apparatus (1) according to any one of the first to fifth aspects, wherein all lines start accumulation before the preliminary light emission is started, The number of the lines of the pixels (15c) selected at the time of one preliminary light emission is determined so that all the lines are in an accumulation state within the preliminary light emission time. (1).
Note that the configuration described with reference numerals may be modified as appropriate, and at least a part of the configuration may be replaced with another component.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can obtain | require the light quantity of light emission accurately can be provided.

1 is a conceptual configuration diagram of a camera to which an embodiment of the present invention is applied. It is a block block diagram of a camera. It is a conceptual diagram which shows the basic structure of 11 A of photometry image sensors. It is a figure which shows the position of the color filter arrangement | sequence of a pixel array part, and the focus point for focus detection. It is a conceptual diagram explaining the line selection at the time of preliminary light emission. It is a figure explaining the line reading at the time of preliminary light emission. It is a flowchart of the master flash control by a camera microcomputer.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a conceptual configuration diagram of a camera 1 to which an embodiment of the present invention is applied. FIG. 2 is a block configuration diagram of the camera 1.

A camera 1 shown in FIG. 1 is a digital single-lens reflex camera including a camera body 10 and a photographing lens 20 that can be attached to and detached from the camera body 10.
The photographic lens 20 constitutes an imaging optical system and is capable of autofocus driving, a lens driving unit 22 (see FIG. 2) for moving and driving the lens group 21, a diaphragm 23, and a diaphragm control unit 24. A distance encoder 25 (see FIG. 2) that outputs a signal corresponding to the rotation angle of the distance feeling corresponding to the lens extension amount, and a lens microcomputer 26 (see FIG. 2) are provided.

The distance encoder 25 outputs a signal corresponding to the rotation angle of the distance ring corresponding to the extension amount of the lens group 21 to the lens microcomputer 26.
The lens microcomputer 26 processes the signal from the distance encoder 25 to obtain distance information. This distance information is communicated to a camera microcomputer 30 of the camera body 10 described later.
Then, the photographing lens 20 forms an image of the incident subject light on the imaging element 11A in the imaging unit 11 of the camera body 10 described later.

  The camera body 10 includes an imaging unit 11, a shutter 12, a quick return mirror 13, a finder unit 14, a photometry unit 15, a focus detection unit 16, a flash light emission unit 17, and a flash microcomputer 18 (see FIG. 2). ), A release switch 19, and a camera microcomputer 30 (see FIG. 2).

The imaging unit 11 includes an imaging element 11A that converts an optical subject image into an electrical signal. The image sensor 11A is a CCD (Charge Coupled Device Image Sensor) or a CMOS sensor in which a plurality of pixels (charge storage photoelectric conversion elements) are two-dimensionally arranged.
The shutter 12 opens and closes to control the exposure time of the image sensor 11 </ b> A in the imaging unit 11.
The quick return mirror 13 swings between an action position (indicated by a solid line in FIG. 1) interposed in the optical path of the subject light from the photographing lens 20 to the imaging unit 11 and an inactive position retracted from the optical path. It is arranged to be possible. The quick return mirror 13 reflects and bends the subject light upward and guides it toward the viewfinder 14 at the operating position. Further, on the back side of the quick return mirror 13, a sub mirror 16 </ b> A in a focus detection unit 16 described later is disposed.

The viewfinder section 14 includes a diffusion screen 14A on which a subject image formed by the photographing lens 20 is formed, a condenser lens 14B, a pentaprism 14C, and an eyepiece 14D.
In the finder unit 14, the light beam reflected by the quick return mirror 13 forms an image on the diffusing screen 14 </ b> A in the shooting standby state. This image is observed by the photographer through the condenser lens 14B, the pentaprism 14C, and the eyepiece 14D. A part of the light beam formed on the diffusing screen 14 </ b> A is incident on the photometry unit 15.

  The photometric unit 15 includes a photometric prism 15A, a photometric lens 15B, and a photometric image sensor 15C. In the photometry unit 15, a part of the light beam imaged on the diffusion screen 14A in the finder unit 14 is re-imaged on the photometry image sensor 15C via the photometry prism 15A and the photometry lens 15B.

The photometric image sensor 15C is composed of a CMOS sensor. FIG. 3 is a conceptual diagram showing the basic structure of the photometric imaging element 15C in the photometric unit 15. As shown in the figure, a pixel array unit 151, a line selection unit 152, an AD converter unit 153, and a column memory unit 154 are provided.
In this configuration example, the pixel array unit 151 includes 360 pixels 15c in the x direction (SensorW), 240 pixels 15c in the y direction (SensorH), and 360 × 240 = 86400 pixels 15c as a whole. x is 0 to 359, and y is 0 to 239. That is, 360 pixels arranged in the x direction constitute one line, and 240 lines are arranged in the y direction.

The line selection unit 152 performs charge accumulation and readout control for the line designated by the camera microcomputer 30. The accumulation start / read is a rolling shutter system in which the timing is different for all lines.
The AD converter unit 153 receives the analog output value for each column read by the line selection unit 152, and converts this into a digital signal.
The column memory unit 154 temporarily stores the digital signal for each column converted by the AD converter unit 153.

The photometric imaging element 15C configured as described above captures the subject image formed through the photometric prism 15A and the photometric lens 15B as a photometric image. The imaging area by the photometric imaging element 15C matches the imaging area of the imaging element 11A in the imaging unit 11, and only the resolution is different.
The photometric unit 15 is controlled by the camera microcomputer 30 and outputs photometric image information captured by the photometric image sensor 15 </ b> C to the camera microcomputer 30.

The focus detection unit 16 includes a sub mirror 16A disposed on the back surface of the quick return mirror 13, a focus detection optical system 16B, and a distance measuring element 16C.
The distance measuring element 16C outputs a focus detection signal corresponding to the image received by the CCD line sensor.

  The focus detection unit 16 performs focus detection by a pupil division method. That is, a part of subject light transmitted through the semi-transmission area of the quick return mirror 13 is reflected by the sub mirror 16A and guided to the focus detection optical system 16B, and the light beam is divided into two by the focus detection optical system 16B and the distance measuring element. An image is formed on 16C, and the phase difference is detected by the distance measuring element 16C. The in-focus state detected by the focus detection unit 16 is output to the camera microcomputer 30 as control information.

  FIG. 4 is a diagram showing the color filter array of the pixel array unit 151 and the position of the focus point for focus detection in the photometric image sensor 15C. As shown in the figure, the focus detection unit 16 detects the focus state for three regions (focus point AFA) of the object scene. Note that the focus detection method is not limited to this, and a method of detecting contrast from imaging information of the imaging element 11A in the imaging unit 11 may be used.

Although not shown in detail, the flash light emitting unit 17 includes a xenon tube, a reflector, a capacitor, and the like. The flash light emitting unit 17 is used as a light source during night photography where the subject light quantity is insufficient, and as an auxiliary light source during backlighting during steady light photography.
The flash microcomputer 18 performs light emission control of the flash light emitting unit 17 under the control of the camera microcomputer 30.

  The camera microcomputer 30 is configured by a CPU or the like, and includes a memory 31 that stores programs and setting tables. The camera microcomputer 30 controls the operation of the camera body 10 according to the program and setting table stored in the memory 31 and controls the photographing lens 20 via the lens microcomputer 26. That is, the camera microcomputer 30 comprehensively controls the camera 1. Control by the camera microcomputer 30 is roughly divided into photometry, autofocus, and master flash control.

  Photometric control in the camera microcomputer 30 includes photometric image information input from the photometric unit 15, lens information such as the open F value, focal length, and exit pupil position of the photographing lens 20 stored in the lens microcomputer 26, and an imaging unit. 11 is calculated based on the sensitivity setting information of the image sensor 11A in FIG. Then, it is converted into an aperture value and a shutter value, and output to the aperture controller 24 and the shutter 12. The aperture control unit 24 controls the aperture / reduction of the aperture 23 in accordance with the release signal from the release switch 19.

  In the autofocus control, the lens group 21 is driven by the lens driving unit 22 according to the in-focus state detected by the focus detection unit 16. That is, the focus state information detected by the focus detection unit 16 is arithmetically processed to calculate the lens driving amount, and the lens group 21 of the photographing lens 20 is driven to the in-focus state via the lens driving unit 22.

  In the master flash control, when the flash light emitting unit 17 is used, the gain of the photometric unit is calculated based on the photometric value, the aperture value, the sensitivity value, the distance value, etc., and the gain is set. Thereafter, the flash light emitting unit 17 is preliminarily emitted through the flash microcomputer 18, and the main light emission amount instruction value is calculated based on the detection information by the photometric imaging element 15C of the photometry unit 15 according to the subject reflected light amount by the preliminary light emission. The actual emission instruction value is output to the flashing microcomputer 18. This master flash control will be described in detail later.

The camera 1 is controlled by the camera microcomputer 30 at the time of shooting and operates as follows.
That is, when the release switch 19 is pressed, the camera microcomputer 30 sets the aperture value and the shutter value by photometric control, and brings the photographing lens 20 into focus by autofocus control. Then, the quick return mirror 13 is retracted out of the photographing optical path, the diaphragm 23 of the photographing lens 20 is narrowed, the shutter 12 is opened, and the subject image by the photographing lens 20 is exposed to the image pickup device 11A of the image pickup unit 11. After a predetermined exposure time, the shutter 12 is closed and the quick return mirror 13 is returned to the operating position. Thereafter, the digital image data is read from the image pickup unit 11 (image pickup element 11A) and recorded in a recording medium such as a buffer memory and a memory card (not shown). Note that the imaging element 11A of the imaging unit 11 has linear input / output characteristics of incident light quantity and output voltage, and the image data read at this time is digital data after AD conversion.

  Here, in the case of shooting with only the steady light without using the flash light emitting unit 17 (without performing the master flash control), the camera microcomputer 30 uses all the pixels of the photometric imaging element 15C in the photometric unit 11 in the photometric control. Use photometric images. That is, all lines are designated in the line selection unit 152.

On the other hand, when the flash light emitting unit 17 is used, the camera microcomputer 30 performs master flash control.
In the master flash control, the flash emission unit 17 is preliminarily emitted a plurality of times (for example, twice) prior to the main light emission, and photometric imaging information is acquired by the photometric imaging element 15C, and the main light emission amount is calculated based on the photometric imaging information. To be accurate. In this preliminary light emission, the line selection unit 152 performs line selection from all pixels (lines) of the pixel array unit 151, and a different line is selected for each preliminary light emission.

  FIG. 5 is a conceptual diagram illustrating line selection during preliminary light emission. FIG. 6 is a diagram for explaining line reading during preliminary light emission. As shown in FIG. 5, L1 and L3 are selected for the first preliminary light emission, and L2 and L4 are selected for the second preliminary light emission. In the figure, L2 is located between L1 and L3, and L4 is at an interval equal to L2 with respect to L3. There are lines between the lines (L1, L2, L3, L4), but the number depends on the setting.

As a result, as shown in FIG. 6A, photometric imaging information is obtained by twice the number of lines (pixels) at the time of one preliminary light emission by the two times of preliminary light emission.
That is, as shown in FIG. 6B, when all the lines of the pixel array unit 151 are applied with only one preliminary light emission, the read start time tx of the final line is later than the accumulation time t0. The entire image cannot be captured, and the photometric imaging information is insufficient. In this case, line thinning is performed to capture the entire screen.

The read start time t1 of the final line after thinning is
Since t1 = tx × number of applied lines / total number of lines, it is possible to shorten the time until the start of reading of the final line.
T1 in FIG. 6B is
In this example, t1 = tx × 1/6.
However, in this case, although the entire screen can be imaged, the number of applied lines is small, so the resolution is low, and the photometric imaging information is insufficient and high photometric accuracy may not be obtained especially for subjects that exhibit fine light and dark patterns. There is.

Therefore, as shown in FIG. 6 (a), preliminary light emission is performed a plurality of times (here, twice) at an interval ti as quickly as possible, and the number of applied lines is the same for the first and second preliminary light emission. Then, the line to be applied is changed and the photometric imaging information of both is added up. Thereby, even if the read start time t1 of the last line is the same, the amount of information (number of applied lines) is doubled to improve the photometric accuracy, and the calculation accuracy of the main light emission amount can be improved. In order to obtain the same photometric imaging information by one preliminary light emission, as shown at t2 in FIG.
t2 = tx × 1/6 × 2 = tx × 1/3
Thus, the time until reading starts increases.
In this example, the preliminary light emission is described as being twice, but it may be three or more times. As the number of times is increased, more photometric imaging information can be obtained and the photometric accuracy can be improved.

Here, the number of pre-flashes and the number of lines read by one pre-flash are determined by the camera microcomputer 30 based on the mode set by a command dial (not shown), the image taken by the photometric image sensor 15C, the result of pre-flash, etc. For example, it is set by analyzing a photographic scene based on a program or table stored in the memory 31 (see FIG. 2).
In this case, first, a resolution (total number of lines to be selected) necessary for obtaining desired photometric imaging information is set, and the number of preliminary light emission is determined by dividing the resolution by the number of lines read by one preliminary light emission.
The number of lines read in one preliminary light emission is such that all the selected lines are in a charge accumulation state at the time of preliminary light emission (that is, the charge accumulation of the first line is before completion and the charge accumulation of the last line is Set after).

The master flash control by the camera microcomputer 30 will be described in detail according to the flowchart shown in FIG. FIG. 7 is a flowchart of master flash control by the camera microcomputer 30.
Hereinafter, the steps shown in FIG. 7 will be described in order. In the following description and drawings, “step” is also abbreviated as “S”.

[Step 101]
The number of preliminary light emission (MonCnt) and the number of lines to be read in each preliminary light emission (LineCnt) are set. As described above, this setting is performed according to the shooting mode, the image captured by the photometric image sensor 15C, the result of one preliminary light emission, and the like. In this configuration example, MonCnt = 2 and LineCnt = 20.

[Step 102]
Calculate the decimation interval (Interval). First, the total number (SumLine) of lines read out by preliminary light emission is calculated according to equation (1).
SumLine = MonCnt × LineCnt (1)
In this configuration example,
MonCnt = 2, LineCnt = 20,
SumLine = 40
It becomes.
Next, using SumLine and SensorH, Interval is obtained by equation (2).
Interval = Round (SensorH / SumLine) ... Formula (2)
Here, Round () is a function that outputs a rounded result.
From SensorH = 24, SumLine = 40,
Interval = 6
It becomes.

[Step 103]
The camera microcomputer 30 secures a memory area.
ReadLine [i] (i: 0 to SumLine-1)
The number of elements is SumLine.
Store the line numbers to be read out in ascending order.
ArrayReadLine [m, n] (m: 0 to MonCnt-1, n: 0 to LineCnt-1)
The number of elements is the same as ReadLine.
The line numbers to be read in each preliminary light emission are organized and stored for each value of the subscript m.
Voymon [x, y] (x: 0 to SensorW-1, y: 0 to SumLine-1)
The number of elements is SensorW x SumLine.
A pixel value including reflected light and stationary light received by preliminary light emission is stored.
Initialize all elements with -1.
Voyback [x, y] (x: 0 to SensorW-1, y: 0 to SumLine-1)
The number of elements is the same as Voymon.
A pixel value of only steady light when preliminary light emission is not performed is stored.
Initialize all elements with -1.
Voy [x, y] (x: 0 to SensorW-1, y: 0 to SumLine-1)
The number of elements is the same as Voymon.
Stores the pixel value of only the reflected light calculated by Voymon and Voyback.
Initialize all elements with -1.
In this configuration example,
ReadLine [i] (i: 0 to 39)
ArrayReadLine [m, n] (m: 0 to 1, n: 0 to 19)
Voymon [x, y] (x: O to 359, y: O to 39)
Voyback [x, y] (x: 0 to 359, y: 0 to 39)
Voy [x, y] (x: 0 to 359, y: 0 to 39)
It becomes.

[Step 104]
1. Calculate ReadLine.
ReadLine [i] (i: 0 to SumLine-1) is calculated according to equation (3).
ReadLine [i] = i × Inteval (3)
From SumLine = 40, Interval = 6,
The line number ReadLine [i] (i: 0 to 39) is as follows.
ReadLine [i] = (0, 6, 12, 18, 24, 30, 36, 42, 48, 54, '60, 66, 72, 78, 84, 90, 96, 102, 108, 114, 120, 126 132, 138, 144, 150, 156, 162, 168, 174, 180, 186, 192, 198, 204, 210, 216, 222, 228, 234)
2. ArrayReadLine is calculated.
The obtained ReadLine [i] is divided for each number of preliminary light emission.
ArrayReadLine [m, n] (m: 0 to MonCnt-1, n: 0 to LineCnt-1)
= ReadLine [MonCnt × n + m]
In this configuration example, ArrayReadLine [m, n] (m: 0 to 1, n: 0 to 19)
= ReadLine [2 × n + m].
The readout line for the first preliminary light emission is as follows.
ArrayReadLine [0, n] = (0, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, 180, 192, 204, 216, 228)
The readout line for the second preliminary light emission is as follows.
ArrayReadLine [1, n] = (6, 18, 30, 42, 54, 66, 78, 90, 102, 114, 126, 138, 150, 162, 174, 186, 198, 210, 222, 234)

[Step 105]
First preliminary light emission The readout line number of the photometric image sensor 15C in the first preliminary light emission is set in the line selector 152.
The read line number to be set is ArrayReadLine [0, n] (n: 0 to 19). However, if
ArrayReadLine [m, n]> (SensorH-1)
The corresponding line number is not set in the line selection unit 152 because the corresponding line does not physically exist.

[Step 106]
The preliminary light emission of the flash light emitting unit 17 is instructed through the flash microcomputer 18. The flash light emitting unit 17 performs preliminary light emission with a predetermined minute light amount accordingly.

[Step 107]
Reflected light from the subject due to the preliminary light emission forms a subject image on the diffusion screen 14 </ b> A of the finder unit 14 via the photographing lens 20 and the quick return mirror 13. The photometric image sensor 15C of the photometry unit 15 receives the subject image on the diffusion screen 510.

[Step 108]
A pixel value is read from the column memory unit 154. The pixel values for one line read in order are stored in Voymon [x, y] (x: 0 to 359, y: 0 to 39).
Y is determined according to equation (4).
N (0 to 19) in Expression (4) represents the order in which each line is read.
y = MonCnt × n + 0 = 2 × n (4)

[Step 109]
Steady light is received without performing preliminary light emission.
The same gain, the same accumulation time, and the same readout line setting as when the preliminary light emission is performed. The steady light luminance value Voyback [x, y] (x: 0 to 359, y: 0 to 39) at this time is obtained.

[Step 110]
Second preliminary light emission The read line number of the photometric image sensor 15C in the second preliminary light emission is set in the line selection unit 152.
The read line number to be set is ArrayReadLine [1, n] (n: 0 to 19).
However, the line number satisfying ArrayReadLine [m, n]> (SensorH-1) is not set in the line selection unit 152 because the corresponding line does not physically exist.

[Step 111]
The preliminary light emission of the flash light emitting unit 17 is instructed through the flash microcomputer 18. The flash light emitting unit 17 performs preliminary light emission with a predetermined minute light amount accordingly.

[Step 112]
Reflected light from the subject due to the preliminary light emission forms a subject image on the diffusion screen 14 </ b> A of the finder unit 14 via the photographing lens 20 and the quick return mirror 13. The photometric image sensor 15C of the photometry unit 15 receives the subject image on the diffusion screen 510.

[Step 113]
A pixel value is read from the column memory unit 154.
The pixel values for one line read in order are stored in Voymon [x, y] (x: 0 to 359, y: 0 to 39).
Y is determined according to equation (5).
y = MonCnt × n + 1 = 2 × n + 1 (5)

[Step 114]
Light reception is performed without performing preliminary light emission. The same gain, the same accumulation time, and the same readout line setting as when the preliminary light emission is performed. The steady light luminance value Voyback [x, y] (x: 0 to 359, y: 0 to 39) at this time is obtained.

[Step 115]
Steady light removal
Using Voymon and Voyback, the effect of stationary light is removed by equation (6).
A stationary light removal image Voy [x, y] (x: 0 to 359, y: 0 to 39) is obtained.
Voy [x, y] = Voymon [x, y] −Voyback [x, y] (6)

[Step 116]
In the steady light removal image Voy [i, j] obtained in step 115, the average value of the G pixel components is calculated and is defined as VoyAve. However, when Voy [x, y] = − 1, the value is not used for calculating the average value.
Here, the step difference (unit EV) between the light emission guide number and the preliminary light emission guide number GNMon is referred to as the light emission amount step difference. Further, the difference in the number of light emission steps is set to KGN. Using the average value VoyAve of G pixel components in Voy [i, j], KGN is obtained by Expression (7).
KGN = −log2 (VoyAve) −Av0 + Av + KGNCONST Equation (7)
In equation (7), KGNCONST is a difference in the number of light emission steps for a captured image to have an appropriate luminance value with the main light emission with respect to a standard reflectance subject such as a standard reflector with 18% reflectance. Av0 is the open F value (Apex) of the photographing lens 20, and Av is the aperture F value (Apex value) at the time of photographing. The main light emission amount GNHon is obtained by Expression (8) using KGN of Expression (7).
GNHon = GNMon × (√2) ^ KGN (8)

[Step 117]
The quick return mirror 13 is retracted out of the photographing optical path, the shutter 12 is opened, and the diaphragm 23 is narrowed down. Thereafter, the flash emission unit 17 is instructed with the light emission amount GNHon obtained in step 116 to start the main light emission.

[Step 118]
A subject image formed by the photographic lens 20 is formed on the image pickup device 11A of the image pickup unit 11, and charge accumulation starts. The flash microcomputer 18 stops light emission when the target light emission amount GNHon is reached. When a predetermined exposure period has elapsed, the shutter 12 is closed and the quick return mirror 13 is returned to the operating position. Thereafter, digital image data is read from the image sensor 11 </ b> A of the imaging unit 11.

  As described above, when the preliminary light emission is performed twice in steps 101 to 118, the amount of information is doubled as compared with the case where the preliminary light emission is performed once. Therefore, more accurate subject information can be acquired, and the calculation accuracy of the main light emission amount is improved.

As described above, this embodiment has the following effects.
(1) In master flash control by the camera microcomputer 30 of the camera 1, the flash light emitting unit 17 is preliminarily lighted a plurality of times (for example, twice), and photometric imaging information is obtained by the photometric image sensor 15C at the time of this preliminary light emission. At this time, the line selection unit 152 performs line selection from the pixels (lines) of the pixel array unit 151, and a different line is selected for each preliminary light emission. Thereby, photometric imaging information is obtained by a plurality of times of preliminary light emission using lines (pixels) that are twice the number of times of preliminary light emission as compared with the case of one preliminary light emission. As a result, the amount of information becomes twice the number of times of preliminary light emission compared to the case where the preliminary light emission is performed once, so that more accurate subject information can be acquired, and the calculation accuracy of the main light emission amount is improved.

(Deformation)
The present invention is not limited to the above-described embodiment, and various modifications and changes as described below are possible, and these are also within the scope of the present invention.
(1) Numerical values such as the number of pixels and the number of lines of the photometric imaging element 15C in the above embodiment are merely examples, and are not limited thereto, and can be set as appropriate.

(2) In the above-described embodiment, the present invention is applied to a digital single-lens reflex camera with interchangeable lenses. However, the present invention is not limited to this, and an optical viewfinder is not provided even if lenses can be interchanged. The present invention may be applied to a digital camera or a compact digital camera with a fixed lens. In that case, you may comprise so that the photometric imaging information in master flash control may be acquired using the image pick-up element which image | photographs (image pick-up element 11A in embodiment).
In addition, although embodiment and a deformation | transformation form can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited to the embodiment described above.

  1: camera, 10: camera body, 11: imaging unit, 11A: imaging device, 15: photometry unit, 15C: photometry imaging device, 151: pixel array unit, 152: line selection unit, 153: AD converter unit, 154 : Column memory section, 17: Flash light emitting section, 18: Flash microcomputer, 30: Camera microcomputer, 31: Memory, 20: Shooting lens

Claims (6)

A flash emission unit capable of multiple preliminary flashes;
A photometric unit that includes a light receiving element having a plurality of pixels that receive the preliminary light emission and accumulates electric charge according to the amount of received light, and outputs a photometric signal according to the accumulated charge;
A calculation unit that calculates a main light emission amount of the flash light emission unit using the photometry signal output from the photometry unit;
The plurality of light receiving elements are two-dimensionally arranged, and for each preliminary light emission, light receiving elements arranged along different lines are selected from the two-dimensionally arranged light receiving elements, and charges are accumulated. An imaging device characterized by the above. The imaging device according to claim 1,
There are a plurality of lines of the light receiving elements selected in one preliminary light emission;
An imaging device characterized by the above. The imaging device according to claim 1 or 2,
An imaging apparatus characterized in that the charge accumulation start timing in the light receiving element is different for all lines. The imaging device according to any one of claims 1 to 3,
A scene determination unit for determining a shooting scene;
In accordance with the scene determination result of the scene determination unit, the number of times of preliminary light emission that determines the number of times of preliminary light emission,
An imaging apparatus comprising: The imaging device according to any one of claims 1 to 4, wherein
A scene determination unit for determining a shooting scene;
A line number determination unit that determines the total number of the lines selected in the plurality of preliminary light emissions according to the scene determination result of the scene determination unit;
An imaging apparatus comprising: The imaging device according to any one of claims 1 to 5,
The light receiving element selected at the time of one preliminary light emission so that all lines start accumulation before the preliminary light emission is started and all the lines are accumulated within the preliminary light emission time. The number of said lines of is determined,
An imaging device characterized by the above.

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