JP2010272966A - Photometric device, and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photometric device for which a photometric accuracy is ensured, and to provide an imaging apparatus on which the photometric device is mounted. <P>SOLUTION: A photometric device has a photometric sensor 106, a re-image-formation optical system 105, and an optical system control device 111. The photometric sensor 106 captures an image by a lens system 51 to output an imaging signal. The re-image-formation optical system 105 different from the lens system 51 is arranged in an optical path between the lens system 51 and the photometric sensor 106. The optical system control device 111 controls an image formation state of an image for the photometric sensor 106. An electronic camera 1 has the photometric device and an imaging element 110 capturing the image by the lens system 51. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photometric device and an imaging device equipped with the photometric device.

  2. Description of the Related Art Conventionally, a technique for measuring reflected light from a subject by so-called preliminary light emission from a flash device of an imaging device and determining a light emission amount at the time of photographing is known (for example, see Patent Document 1).

  In the invention of Patent Literature 1, the charge accumulation time of the image sensor is shortened by thinning out the output of the pixels of the image sensor that receives reflected light from the subject in units of rows, and the influence of light other than the reflected light due to preliminary light emission is reduced. An example of a technique for reducing the above is disclosed.

JP 2006-50337 A

  However, in the invention of Patent Document 1, when the charge is accumulated by thinning out the output of the pixel of the image sensor in units of rows, the reflected light from the subject at the position corresponding to the dead zone portion between the rows cannot be used for measurement. There arises a problem that the photometric accuracy is lowered.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a photometric device in which photometric accuracy is ensured and an imaging device equipped with the photometric device.

  A photometric device according to a first invention includes an imaging means, a sub optical system, and a control unit. The imaging means captures an image by the optical system and outputs an imaging signal. A sub optical system different from the optical system is disposed in the optical path between the optical system and the imaging means. The control unit controls the image formation state of the image with respect to the imaging unit.

  In a second aspect based on the first aspect, the control unit changes the imaging state by the sub optical system in accordance with the operation state of the imaging means.

  In a third aspect based on the second aspect, the control unit shifts the image formation position of the image from above the imaging means when the imaging means selectively outputs the imaging signal.

  In a fourth aspect based on the third aspect, when the image pickup means outputs an image pickup signal corresponding to a predetermined area of the image by the optical system, the control unit sets the image formation position on the image pickup means. .

  In a fifth aspect based on the third aspect, when the control unit detects an image pickup signal corresponding to a specific image from an image pickup signal obtained by the image pickup means, the image forming position is set on the image pickup means.

  In a sixth aspect based on the first aspect, the sub optical system includes at least one of a lens, a diffraction grating, and an electro-optical element that changes a refractive index of transmitted light according to the strength of the electric field. It is a waste.

  An imaging device according to a seventh aspect includes the photometric device according to any one of claims 1 to 6 and an imaging element that captures an image by an optical system.

  ADVANTAGE OF THE INVENTION According to this invention, the photometry apparatus with which photometric accuracy was ensured and the imaging device carrying the photometry apparatus can be provided.

1 is a block diagram illustrating an internal configuration of an electronic camera 1 that is an embodiment of an imaging apparatus of the present invention. The figure which shows the internal structure of the electronic camera 1 and the flash device 150 which are shown in FIG. A flowchart showing an example of the operation of the electronic camera 1 The figure which showed the arrangement | sequence of the pixel of the image based on the image signal which the photometry sensor 106 outputs A figure showing an example of a subject that falls within the shooting range The figure which shows an example of the distribution information of the brightness | luminance which the imaging device of the photometry sensor 106 output Illustration of an example showing the area to be metered Diagram explaining the thinning operation The figure which shows an example of the distribution information of the brightness | luminance which the image sensor of the photometry sensor 106 outputs The figure which shows an example of the distribution information of the brightness | luminance which the image sensor of the photometry sensor 106 outputs The figure which shows the internal structure of the electronic camera 2 in 2nd Embodiment. A flowchart showing an example of the operation of the electronic camera 2

(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view showing a main configuration of an electronic camera 1 which is an embodiment of an imaging apparatus of the present invention.

  The electronic camera 1 is, for example, a single-lens reflex electronic camera, and includes a camera body 100 and a photographing lens unit 50. The taking lens unit 50 is detachably attached to a lens mount 100 a formed on the front surface of the camera body 100 in order to guide subject light to the camera body 100. Thereby, the camera body 100 and the photographing lens unit 50 are electrically connected.

  Further, a flash device 150 for irradiating the subject with irradiation light is detachably attached to the camera body 100 to a hot shoe (connection terminal) 150 a formed on the upper surface of the camera body 100. As a result, the camera body 100 and the flash device 150 are electrically connected.

  The taking lens unit 50 has a lens system 51 and a diaphragm 52. The lens system 51 includes a plurality of lenses including a focus lens 51a for focusing on a subject and a zoom lens 51b for zooming the subject image. Here, for convenience of explanation, two lenses are illustrated. The focus lens 51a and the zoom lens 51b are adjusted in position in the optical axis direction by a lens driving circuit (not shown). The diaphragm 52 adjusts the amount of light incident on the camera body 100 by opening and closing the diaphragm blades. A diaphragm control unit (not shown) controls the aperture of the diaphragm 52.

  The camera body 100 includes a quick return mirror 102, a viewfinder screen 103, a penta roof prism 104, a re-imaging optical system 105, a photometric sensor 106, an eyepiece lens 107, a release button 108, a mechanical shutter 109, an image sensor 110, and an optical system controller. 111 and an optical viewfinder 112. The re-imaging optical system 105, the photometric sensor 106, and the optical system control device 111 correspond to an example of a photometric device.

  The quick return mirror 102 is rotatably provided on the optical axis indicated by the dotted line. When the subject is not photographed, the quick return mirror 102 is arranged at a position oblique to the optical axis by a mirror control unit (not shown). In this case, the quick return mirror 102 receives the subject light incident on the camera body 100 via the lens system 51, reflects the subject light, and guides it to the finder screen 103.

  On the other hand, when imaging an object, the quick return mirror 102 is retracted to a position indicated by a dotted line in the figure by rotation, and the object light incident on the camera body 100 from the object is guided to the image sensor 110.

  The finder screen 103 diffuses the subject light guided by the quick return mirror 102 and guides the diffused subject light to the penta roof prism 104 when the image sensor 110 does not capture an image. The penta roof prism 104 reflects the subject light diffused by the finder screen 103 and guides it to the re-imaging optical system 105 and the eyepiece lens 107.

  The eyepiece 107 forms the subject light guided by the penta roof prism 104 as a subject image. The photographer can determine the composition, frame, etc. of the subject by viewing the subject image formed by the eyepiece lens 107 via the optical viewfinder 112.

  The re-imaging optical system 105 is composed of a plurality of lenses, for example, and re-images the subject image on the photometric sensor 106. For convenience of explanation, the re-imaging optical system 105 is shown as a single lens in this embodiment. The optical system driving device 111 performs control such as moving a plurality of lenses of the re-imaging optical system 105 on the optical axis. The optical system drive device 111 reduces the amount of blur of subject light imaged on the imaging surface of the image sensor of the photometric sensor 106 in accordance with the amount of movement by which the plurality of lenses of the re-imaging optical system 105 are moved on the optical axis. Change.

  The photometric sensor 106 includes photometric means for measuring an image by an optical system based on an image signal (imaging signal). Specifically, the photometric sensor 106 includes an imaging unit that captures a subject image by an optical system and outputs an image signal. The photometric sensor 106 includes, for example, a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor that can read an arbitrary line by XY addressing. For example, three types of color filters of red (R), green (G), and blue (B) are arranged in a Bayer array on the imaging surface of the imaging element in order to detect the color of the subject image. The image signal output from the image sensor is subjected to gain adjustment, A / D conversion, and the like in the photometric sensor 106, and temporarily stored in a RAM (Random Access Memory) 13 or a memory in a CPU (Central Processing Unit) 18 described later. To be recorded. The image sensor used for the photometric sensor 106 may be a CCD (Charge Coupled Device) type image sensor.

  The image sensor employs a rolling shutter system that controls the charge accumulation time for each line by addressing. Thereby, in the rolling shutter system, it is possible to select an operation state in which the image pickup device accumulates and reads out charges of all lines or an operation state in which charges are accumulated and read out by thinning out in units of lines (decimation readout).

  The release button 108 receives an instruction input for a half-press operation (instruction input for starting an operation such as autofocus (AF) before photographing) and a full-press operation (starting an imaging operation).

  The mechanical shutter 109 includes an openable / closable shutter curtain, and switches between a light shielding state where light incident on the image sensor 110 is shielded and a non-light shield state where incident light reaches the image sensor 110 by opening / closing the shutter curtain.

  The image sensor 110 captures an image by an optical system. For example, the image sensor 110 may be a CCD type or CMOS type image sensor. As an example, three types of color filters R, G, and B are arranged in a Bayer array on the imaging surface of the imaging element 110.

  FIG. 2 is a diagram showing an internal configuration of the electronic camera 1 and the flash device 150 shown in FIG. As shown in FIG. 2, the electronic camera 1 includes the camera body 100 and the photographing lens unit 50 as described above. In FIG. 2, the viewfinder screen 103, the penta roof prism 104, the eyepiece lens 107, the mechanical shutter 109, the optical viewfinder 112, and the like shown in FIG.

  The camera body 100 includes a quick return mirror 102, a re-imaging optical system 105, a photometric sensor 106, an optical system control device 111, an image sensor 110, and an analog front end unit (hereinafter referred to as “AFE”) 11. , An image processing unit 12, a RAM 13, a ROM (Read Only Memory) 14, a recording interface unit (hereinafter referred to as “recording I / F unit”) 15, a display monitor 16, an operation unit 17, and a release button. 108, a CPU 18, a bus 19, a lens mount 100a, and a hot shoe 150a.

  Among these, the AFE 11, the image processing unit 12, the RAM 13, the ROM 14, the recording I / F unit 15, the display monitor 16, and the CPU 18 are connected to each other via a bus 19.

  The AFE 11 is an analog front end circuit that performs signal processing on an image signal generated by the image sensor 110. The AFE 11 performs image signal gain adjustment, A / D conversion, and the like. The image signal output from the AFE 11 is temporarily recorded in the RAM 13.

  The image processing unit 12 reads an image signal recorded in the RAM 13 and performs various image processing (gradation conversion processing, contour enhancement processing, white balance processing, YC conversion processing, etc.).

  The ROM 14 is a non-volatile memory that stores a program for controlling the electronic camera 1 in advance.

  The recording I / F unit 15 is formed with a connector for connecting a detachable recording medium 30. Then, the recording I / F unit 15 accesses the recording medium 30 connected to the connector according to an instruction from the CPU 18 and performs a recording process of a still image or a moving image. The recording medium 30 is, for example, a non-volatile memory card. FIG. 2 shows the recording medium 30 after being connected to the connector.

  For example, the display monitor 16 displays a still image, an operation menu of the electronic camera 1, and the like. As the display monitor 16, a liquid crystal monitor or the like can be appropriately selected and used.

  The operation unit 17 includes, for example, a command dial for command selection, a power button, and the like. Then, the operation unit 17 receives an instruction input for operating the electronic camera 1. Further, the operation unit 17 receives, for example, a selection input of a still image or moving image shooting mode via the command dial.

  The CPU 18 is a processor that performs overall control of the electronic camera 1. The CPU 18 controls each part of the electronic camera 1 by executing a program stored in advance in the ROM 14. For example, the CPU 18 instructs the optical system control device 111 to control the imaging state. The optical system control device 111 controls the imaging state of the image on the imaging surface (on the imaging means) of the imaging element included in the photometric sensor 106. Specifically, the optical system control device 111 changes the imaging state by moving the lens of the re-imaging optical system 105 according to the operation state of the photometric sensor 106.

  In FIG. 2, the flash device 150 includes a light emitting unit 150b and a light emission control unit 150c. The light emitting unit 150b is a circuit that converts electrical energy charged in the capacitor into light energy. The light emitting unit 150b is provided with, for example, a xenon tube, and performs flash emission by discharging the xenon tube. The light emission control unit 150c receives light emission information indicating the light emission amount and the number of times of light emission of the light emission unit 150b from the CPU 18, and causes the light emission unit 150b to perform preliminary light emission or flash light emission for main photographing based on the received light emission information. .

  Next, the operation of the electronic camera 1 will be described. FIG. 3 is a flowchart showing an example of the operation of the electronic camera 1. This flowchart starts when the CPU 18 of the electronic camera 1 accepts a power-on instruction input. This flowchart is based on the premise that shooting is performed by flash emission.

  Step S101: The CPU 18 issues an instruction to a mirror control unit (not shown), and arranges the quick return mirror 102 at a position oblique to the optical axis as shown in FIG. The CPU 18 issues an instruction to the optical system control device 111 to control the re-imaging optical system 105. The optical system control device 111 moves the plurality of lenses of the re-imaging optical system 105 on the optical axis. As a result, the optical system control device 111 can change the focal position at which the image is re-imaged on the imaging surface of the imaging device of the photometric sensor 106. Here, first, the optical system control device 111 controls the re-imaging optical system 105 so that the subject light incident from the subject forms an image on the imaging surface.

  FIG. 4 is a diagram illustrating an arrangement of image pixels based on an image signal output from the photometric sensor 106. In the present embodiment, as an example for ease of explanation, the horizontal coordinates of the image are represented by i and take values from 0 to 19, and the vertical coordinates of the image are represented by j and are represented by 0 to 29. The value up to is assumed. The output of each pixel after A / D conversion takes a digital value of 0 to 1023 in proportion to the amount of received light.

  FIG. 5 is a diagram illustrating an example of a subject that falls within the shooting range. FIG. 5 shows a composition in which the person P is shown with the light source L in the background for easy understanding.

  Step S102: The CPU 18 sends a drive signal to the photometric sensor 106. The image sensor of the photometric sensor 106 performs charge accumulation (all pixel accumulation) for all pixels by a rolling shutter method.

  Step S103: The CPU 18 acquires an image signal output from the image sensor of the photometric sensor 106. The CPU 18 temporarily records the acquired image signal in the memory in the CPU 18 as luminance distribution information.

  FIG. 6 is a diagram illustrating an example of luminance distribution information output from the image sensor of the photometric sensor 106. In the first embodiment, as shown in FIG. 6, it is assumed that the brightness of the person P at the lower center of the screen is low and the brightness of the light source L area at the upper right of the screen is high.

  Step S104: The CPU 18 calculates a photometric value (control EV, EV: Exposure value) for determining the aperture value at the shutter speed based on the luminance distribution information. FIG. 7 is a diagram illustrating an example of an area to be measured. In the first embodiment, for the calculation of the photometric value, only the output of the portion of the double frame W shown in FIG. 7 is adopted as the photometric data.

  The CPU 18 uses the following formula (1) when calculating the photometric value (control EV).

ここで、式（１）中、Ｖ_ｏｙ[ｉ][ｊ]は、画素中の横座標ｉ、縦座標ｊの画素における出力であり、Ｌｏｇ_２（）の関数は、２を底にした引数の対数値を返す関数である。また、式中の２つのΣは、それぞれ、ｉとｊに対する繰り返し加算であり、ｉとｊの範囲はそれぞれ、図７中の二重枠Ｗの内側に相当する撮像面の座標範囲である。ＢｖＣｏｎｓｔは、測光値を算出するために必要な各種補正値を加味するための定数である。

Here, in equation (1), V _oy [i] [j] is an output at the pixel of the abscissa i and ordinate j in the pixel, and the function of Log ₂ () is an argument with 2 at the bottom. This function returns the logarithm value of. Also, two Σ in the equation are repetitive additions for i and j, respectively, and the ranges of i and j are the coordinate ranges of the imaging plane corresponding to the inside of the double frame W in FIG. BvConst is a constant for adding various correction values necessary for calculating the photometric value.

  The CPU 18 calculates the photometric value by the equation (1), and then calculates the shutter speed and the aperture value in accordance with a so-called program diagram.

  Step S105: The CPU 18 determines whether or not a shooting instruction is input by pressing the release button 108. When the CPU 18 receives an input of shooting instruction (step S105: Yes), the CPU 18 proceeds to step S106. On the other hand, if the CPU 18 has not received an instruction for photographing (step S105: No), the CPU 18 proceeds to step S115 described later.

  Step S106: The CPU 18 starts photographing processing. In the shooting according to the first embodiment, as described above, flash shooting is performed using the flash device 150. The CPU 18 instructs the optical system control device 111 to control the imaging state. The optical system control device 111 moves the plurality of lenses of the re-imaging optical system 105 on the optical axis and shifts the focal position of the image on the imaging surface of the photometric sensor 106 so that the subject image on the imaging surface is blurred.

  Step S107: The CPU 18 thins out the image sensor of the photometric sensor 106 by the rolling shutter method. Here, the reason why the image sensor of the photometric sensor 106 is thinned is to shorten the charge accumulation time of the image sensor and reduce the influence of light other than the reflected light due to the preliminary light emission.

  FIG. 8 is a diagram for explaining the thinning-out operation. The CPU 18 instructs the image sensor of the photometric sensor 106 to perform thinning accumulation in line units (every 3 rows). The imaging device starts to accumulate charges of pixels corresponding to 1/3 of the number of lines (j rows: 0 to 29) (shaded lines in FIG. 8).

  Step S108: The CPU 18 transmits light emission information to the flash device 150, so that the light emission control unit 150c causes the light emission unit 150b to perform preliminary light emission based on the light emission information.

  Step S109: When the thinning-out of the image sensor in the photometric sensor 106 ends, the CPU 18 receives a signal indicating the end.

  Step S110: The CPU 18 temporarily records the image signal output from the image sensor of the photometric sensor 106 in the memory in the CPU 18 as luminance distribution information.

  9 and 10 are diagrams illustrating examples of luminance distribution information output from the image sensor of the photometric sensor 106. FIG. FIG. 9 shows a case where the subject image is blurred, and FIG. 10 shows a state where the focal position of the subject image is kept on the imaging surface.

  In the first embodiment, since the optical system control device 111 blurs the subject image on the imaging surface of the photometric sensor 106 in step S106, it is assumed that there is a light source between the rows that output in the thinning mode. In addition, light can be received by pixels in the peripheral rows (FIG. 9). In other words, the optical system control device 111 performs control so that pixels corresponding to the L1 region shown in white can receive light from the light source even in thinning readout in FIG.

  When the optical system control device 111 controls the re-imaging optical system 105 so as to keep the focus position of the subject image on the imaging surface, and the image sensor of the photometric sensor 106 reads out thinned out, the luminance distribution information shown in FIG. In this case, there arises a problem that light from the light source cannot be received. This is because the image signal of the pixel that receives the light from the light source is not output. Therefore, in the first embodiment, this problem is solved by the processing in step S106.

  Step S111: The CPU 18 calculates the light emission amount of the light emitting unit 150b of the flash device 150 at the time of actual photographing. The following formula (2) is employed for calculating the guide number as the light emission amount.

ここで、第１実施形態では、ステップＳ１１０における測光センサ１０６の出力によって、閃光装置１５０の発光部１５０ｂの発光量を決定する。この場合、図１０に示す輝度の分布情報を用いると発光量を正しく算出できない。第１実施形態では、上述した通り、ステップＳ１０６で光学系制御装置１１１が測光センサ１０６の撮像面上の被写体像をぼかしているため、測光センサ１０６の撮像素子が間引き読み出しをしても、図９に示す通り、周辺の行の画素で光源の光を受光することが可能である。

Here, in the first embodiment, the light emission amount of the light emitting unit 150b of the flash device 150 is determined based on the output of the photometric sensor 106 in step S110. In this case, if the luminance distribution information shown in FIG. 10 is used, the light emission amount cannot be calculated correctly. In the first embodiment, as described above, since the optical system control device 111 blurs the subject image on the imaging surface of the photometric sensor 106 in step S106, even if the image sensor of the photometric sensor 106 performs thinning-out readout, FIG. As shown in FIG. 9, light from the light source can be received by pixels in the peripheral rows.

  Step S112: The CPU 18 causes the quick return mirror 102 to jump up and open the shutter curtain 109.

  Step S113: The CPU 18 transmits a trigger signal to the flash device 150. The light emission control unit 150 causes the light emitting unit 150b to perform main light emission based on the guide number calculated by the equation (2). At this time, the CPU 18 drives the image sensor 110 in synchronization with the main light emission. The AFE 11 performs image signal gain adjustment, A / D conversion, and the like. The image signal output from the AFE 11 is temporarily recorded as image data in the RAM 13. The image processing unit 12 reads the image data recorded in the RAM 13 and performs various image processing (gradation conversion processing, contour enhancement processing, white balance processing, etc.). The CPU 18 records the image data subjected to the image processing by the image processing unit 12 on the recording medium 30 via the recording I / F unit 15.

  Step S114: The CPU 18 returns the quick return mirror 102 to the original position, and closes the shutter curtain 109.

  Step S115: The CPU 18 determines whether or not a power-off instruction input has been received. When the power-off instruction input is not accepted (step S115: No), the process returns to step S101. On the other hand, when a power-off instruction input is received (step S115: Yes), this flowchart ends.

  As described above, according to the first embodiment, it is possible to provide a photometric device in which photometric accuracy is ensured and an electronic camera 1 equipped with the photometric device.

The photometric sensor 106 images subject light from the photographing lens unit 50 (optical system) as a subject image and outputs an imaging signal. Here, as the photometric device, for example, an optical system different from the photographing lens unit 50 is adopted, and the optical system, the re-imaging optical system 105 (sub optical system), and the photometric sensor 106 are arranged on a straight line. The optical path may be arranged in a straight line.
(Second Embodiment)
Next, a second embodiment will be described. In the first embodiment of the present invention and the second embodiment of the present invention, the same elements are denoted by the same reference numerals, description thereof is omitted, and differences will mainly be described.

  In the second embodiment, the optical system control device 111 changes the focal position at which an image is re-imaged on the imaging surface of the image sensor included in the photometric sensor 106 according to the shooting mode of the electronic camera 2. For example, the electronic camera 2 receives an instruction input for selecting the photometric mode of the photometric sensor 106 from the operation unit 17 as a lower mode of the shooting mode. Here, when the photometry mode is a spot photometry mode in which a predetermined area of the photographing area is measured and the exposure is determined from the photometry result, the optical system controller 111 controls the re-imaging optical system 105. The subject image is re-imaged on the imaging surface of the photometric sensor 106.

  FIG. 11 is a diagram showing an internal configuration of the electronic camera 2 in the second embodiment. Compared to the electronic camera 1, in the electronic camera 2, the external flash device 150 is removed from the hot shoe 150a.

  In the electronic camera 2, the CPU 18 also functions as a face detection unit 18a and a motion detection unit 18b. The face detection unit 18a detects a face region based on the image signal output from the photometric sensor 106. Specifically, the face detection unit 18a extracts a face region from an image based on the image signal, and detects its position coordinates and size (range).

  The motion detector 18b detects the motion of the subject based on the temporal change of the image signal output from the photometric sensor 106. In this case, the motion detection unit 18b sequentially calculates motion vectors based on known inter-frame differences. Thereby, the motion detector 18b can detect the motion of the subject. The processing of the face detection unit 18a and the processing of the motion detection unit 18b will be described in the first and second modifications.

  Next, the operation of the electronic camera 2 will be described. FIG. 12 is a flowchart illustrating an example of the operation of the electronic camera 2. This flowchart starts when an instruction input for photometry mode is received after the power is turned on. Here, examples of the photometry mode include a spot photometry mode, an average photometry mode, and a multi-division photometry mode. The average metering mode is a mode in which the average luminance of the photographing region is metered at a time, and the exposure is determined from the metering result. The multi-division photometry mode is a mode in which the photographing area is divided into a plurality of photometry areas, photometry is performed, and exposure is determined from the photometry results.

  Step S201: The CPU 18 determines the photometry mode. When the metering mode is the spot metering mode (step S201: Yes), the process proceeds to step S202-1. On the other hand, when the metering mode is a metering mode other than the spot metering mode (step S201: No), the process proceeds to step S202-2.

  Step S202-1: The CPU 18 gives an instruction to the optical system control device 111, and the optical system control device 111 controls the re-imaging optical system 105, so that the subject light incident from the subject is on the imaging surface. To form an image. Then, the process proceeds to step S203.

  Step S202-2: The CPU 18 gives an instruction to the optical system control device 111, and the optical system control device 111 controls the re-imaging optical system 105, so that the subject light incident from the subject is on the imaging surface. Shift the focus position so that it is blurred. Then, the process proceeds to step S203.

  Step S203: The CPU 18 sends a drive signal toward the photometric sensor 106. Here, when the process of step S202-1 is performed and the process proceeds to step S203, the image sensor of the photometric sensor 106 performs charge accumulation for all pixels by a rolling shutter method. On the other hand, when the process of step S202-2 is performed and the process proceeds to step S203, the image sensor of the photometric sensor 106 performs a thinning operation of the image sensor of the photometric sensor 106 by a rolling shutter method.

  Step S204: The CPU 18 acquires an image signal output from the image sensor of the photometric sensor 106. The CPU 18 temporarily records the acquired image signal in the memory in the CPU 18 as luminance distribution information.

  Step S205: The CPU 18 calculates a photometric value from the luminance distribution information using the above-described equation (1).

  Step S206: The CPU 18 determines whether or not a shooting instruction is input by pressing the release button 108. When the CPU 18 receives an input of shooting instruction (step S206: Yes), the CPU 18 proceeds to step S207. On the other hand, if the CPU 18 has not received a shooting instruction input (step S206: No), the CPU 18 proceeds to step S210 to be described later.

  Step S207: The CPU 18 causes the quick return mirror 102 to jump up and open the shutter curtain 109.

  Step S208: The CPU 18 starts photographing processing. That is, the CPU 18 drives the image sensor 110. The AFE 11 performs image signal gain adjustment, A / D conversion, and the like. The image signal output from the AFE 11 is temporarily recorded as image data in the RAM 13. The image processing unit 12 reads the image data recorded in the RAM 13 and performs various image processing. The CPU 18 records the image data subjected to the image processing by the image processing unit 12 on the recording medium 30 via the recording I / F unit 15.

  Step S209: The CPU 18 returns the quick return mirror 102 to the original position, and closes the shutter curtain 109.

  Step S210: The CPU 18 determines whether or not a power-off instruction input has been received. When the power-off instruction input is not accepted (step S210: No), the process returns to step S201. On the other hand, when a power-off instruction input is received (step S210: Yes), this flowchart ends.

  As described above, in the second embodiment, the imaging state can be changed according to the shooting mode. For example, in the case of spot photometry, the optical system control device 111 sets the imaging position of the subject image on the imaging surface of the photometric sensor 106, and the image sensor of the photometric sensor 106 does not perform thinning readout. In other words, in the second embodiment, spot photometry is performed without blurring the subject image, so that photometry accuracy is ensured. As a result, in the second embodiment, highly accurate exposure control is possible. Note that the image sensor of the photometric sensor 106 may not perform thinning readout for a plurality of lines including an area for spot metering, but may perform thinning readout for an area away from the spot metering area.

(First modification)
Next, a first modification of the second embodiment will be described. In the first modification, the electronic camera 2 includes a face detection mode as a lower mode of the shooting mode. When the CPU 18 receives a face detection mode instruction input via the operation unit 17, the face detection unit 18 a extracts a face region from the image based on the image signal, and detects its position coordinates and size (range). That is, in the first modification, the optical system control device 111 sets the imaging position of the subject image on the imaging surface of the photometric sensor 106 in the face detection mode, and the imaging element of the photometric sensor 106 performs thinning readout. Absent. That is, in the first modification, when performing the face detection process, the face area is extracted without blurring. As a result, in the first modified example, the photometric accuracy is further ensured as compared with the case where thinning-out reading is performed while blurring the subject image.

  When the face detection unit 18a detects a face, it is better that the image sensor of the photometric sensor 106 has a higher number of pixels than the image sensor used for spot photometry.

(Second modification)
Next, a second modification of the second embodiment will be described. In the second modification, the electronic camera 2 includes a mode (tracking mode) for tracking the subject based on the image signal measured by the photometric sensor 106 as a lower mode of the shooting mode. When the CPU 18 receives an instruction input for the tracking mode via the operation unit 17, the motion detection unit 18 b detects the motion of the subject based on the temporal change of the image signal output from the photometric sensor 106. That is, in the second modification, the optical system control device 111 sets the imaging position of the subject image on the imaging surface of the photometric sensor 106 in the tracking mode, and the imaging element of the photometric sensor 106 does not perform thinning readout. . That is, in the second modification, when tracking processing is performed, motion is detected without blurring the subject image. As a result, in the second modified example, the photometric accuracy is further ensured as compared with the case where thinning-out reading is performed while blurring the subject image.
<Supplementary items>
(1) In the first and second embodiments, the re-imaging optical system 105 is composed of a plurality of lenses and is configured to re-image the subject image on the photometric sensor 106. For example, the strength of the electric field An electro-optical element that changes the refractive index of the transmitted light according to the above may be employed to re-image the subject image on the photometric sensor 106. For example, the electro-optic element sandwiches liquid crystal between light transmissive electrodes and controls the alignment of the liquid crystal according to the strength of the electric field applied to the electrodes. As a result, the electro-optic element can change the refractive index of the transmitted light. Further, a diffraction grating having a lens function may be employed to re-image the subject image on the photometric sensor 106. Furthermore, the re-imaging optical system 105 may include at least one of a plurality of lenses, an electro-optic element, and a diffraction grating.
(2) In the first and second embodiments, the single-lens reflex type electronic camera is taken as an example, but a compact type electronic camera that does not require lens replacement may be used. In this case, an image pickup element used in a compact type electronic camera may be used as an image pickup unit of the photometric device of the present invention.
(3) In the second embodiment, for example, the electronic camera 2 may include a flicker detection mode for detecting flicker due to an influence under a fluorescent lamp as a lower mode of the photographing mode. In the flicker detection mode, the optical system control device 111 sets the imaging position of the subject image on the imaging surface of the photometric sensor 106, and the image sensor of the photometric sensor 106 does not perform thinning readout. That is, if the optical system control device 111 blurs the subject image or the image sensor reads out and reads out, it is difficult for the CPU 18 to detect flicker appearing in the image.
(4) In the second embodiment, for example, in the live view mode in which the live image is displayed on the display monitor 16 by using the output of the image sensor of the photometric sensor 106, the optical system control device 111 forms the subject image. While the position is on the imaging surface of the photometric sensor 106, the image sensor of the photometric sensor 106 may perform thinning readout. That is, in the live view mode, the frame rate is prioritized over the image quality, so it is preferable to perform thinning readout.
(5) The photometric device of the present invention may be mounted on, for example, a silver salt film type single-lens reflex camera.

DESCRIPTION OF SYMBOLS 1, 2 ... Electronic camera, 105 ... Re-imaging optical system, 106 ... Photometric sensor, 111 ... Optical system control apparatus, 110 ... Imaging element

Claims (7)

Imaging means for capturing an image by an optical system and outputting an imaging signal;
A sub optical system different from the optical system, disposed in an optical path between the optical system and the imaging means;
A control unit for controlling the imaging state of the image with respect to the imaging means;
A photometric device comprising: The photometric device according to claim 1,
The photometric device according to claim 1, wherein the controller changes the imaging state by the sub optical system in accordance with an operating state of the imaging means. The photometric device according to claim 2,
The photometric apparatus according to claim 1, wherein the control unit shifts the image formation position of the image from the imaging unit when the imaging unit selectively outputs the imaging signal. The photometric device according to claim 3,
The control unit sets an imaging position of the image on the imaging unit when the imaging unit outputs the imaging signal corresponding to a predetermined region of the image by the optical system. Photometric device. The photometric device according to claim 3,
The control unit, when detecting an imaging signal corresponding to a specific image from an imaging signal by the imaging unit, sets the imaging position of the image on the imaging unit. The photometric device according to claim 1,
The sub-optical system includes at least one of a lens, a diffraction grating, and an electro-optical element that changes a refractive index of transmitted light according to the strength of an electric field. The photometric device according to any one of claims 1 to 6,
An image sensor for capturing an image by the optical system;
An imaging apparatus comprising:

Images