JP6455582B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus that acquires an image.

  2. Description of the Related Art Conventionally, in a camera that performs exposure control based on the amount of light received by an image sensor, one that uses optical data such as an aperture value of a photographic lens for calculation for determining an exposure control value is known (see Patent Document 1). ).

JP 2011-61659 A

  If peripheral light reduction is corrected based on the optical data sent from the photographic lens to the camera body, exposure control of through images and moving images may not be performed properly when the optical data changes due to zoom operations. It was.

  An object of the present invention is to provide an imaging apparatus capable of appropriate exposure control.

The present invention captures a moving image by an imaging unit that captures an image by an optical system and outputs a signal, an acquisition unit that acquires first optical data and second optical data of the optical system, and the imaging unit , When the first even aperture of the optical system is changed after obtaining the optical data exposure control was carried out using the first optical data, Ru Kagesu shooting a still image by the imaging unit, the first an imaging apparatus and a control unit that performs exposure control using the pre-Symbol second optical data that different said optical system aperture value is changed to the first optical data after acquiring optical data.

  According to the present invention, it is possible to provide an imaging apparatus capable of appropriate exposure control.

It is a block diagram of the camera 100 in embodiment. 4 is a flowchart showing a basic operation of still image and moving image shooting processing in the camera 100. 4 is a flowchart showing a basic operation of still image and moving image shooting processing in the camera 100. 3 is a conceptual diagram for explaining divided areas of the image sensor 7. FIG.

Embodiments of an imaging apparatus according to the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of a digital single-lens reflex camera (hereinafter also referred to as “camera”) 100 according to the present embodiment.
The camera 100 includes a camera body 1 and a lens unit 2.

  The lens unit 2 is an interchangeable lens that is attached to the mount portion 18 of the camera body 1 so as to be interchangeable. The lens unit 2 includes an imaging optical system 3 as an imaging optical system, a diaphragm 4 and the like. The lens unit 2 has a lens control unit (not shown). The lens control unit transmits data corresponding to the aperture amount of the diaphragm 4 as optical data (described later) to a control unit 10 (described later) of the camera body 1 via a lens communication unit (not illustrated). The optical data may include data relating to the focal length of the imaging optical system 3 and the like.

  The imaging optical system 3 includes a plurality of lens groups (only two lenses are shown in FIG. 1). The plurality of lens groups include a zoom lens group as a zoom optical system and a focus lens group as a focus optical system.

  The diaphragm 4 limits the amount of light flux that passes through the imaging optical system 3 and reaches an imaging device 7 (described later) provided in the camera body 1.

  The camera body 1 includes a quick return mirror 5, a focal plane shutter 6, an imaging device 7 as an imaging unit that photoelectrically converts a subject image, and a moving image (including a through image) as an image captured by the imaging device 7. And a display unit 8 for displaying still images. The camera body 1 includes a camera communication unit (not shown) that communicates with the lens communication unit of the lens unit 2.

  The camera body 1 includes a finder optical system 20, an area sensor 16 that photoelectrically converts a subject image, a control unit 10, and a storage unit 9.

  The quick return mirror 5, the focal plane shutter 6, and the image sensor 7 are arranged along the optical axis OA of the imaging optical system 3, and the finder optical system 20 is arranged in the upper region of the quick return mirror 5.

  When the photographer observes the scene through the finder optical system 20, that is, other than still image shooting and moving image shooting (including through image shooting), the quick return mirror 5 moves from the imaging optical system 3 to the image sensor 7. The light beam crossing the imaging optical path up to and passing through the imaging optical system 3 is reflected upward and guided to the finder optical system 20 (the position of the solid line).

  On the other hand, during still image shooting and moving image shooting (including through image shooting), the quick return mirror 5 is flipped upward, and the light beam that has passed through the imaging optical system 3 is guided to the focal plane shutter 6 and the imaging device 7. It is burned. Thereby, the image data of the subject can be generated based on the imaging signal of the imaging device 7 (the position of the dotted line).

  The finder optical system 20 includes a finder screen 11, a penta roof prism 12, and an eyepiece lens 14.

  The light flux from the subject passes through the imaging optical system 3 and the diaphragm 4 of the camera 100 and is reflected upward by the quick return mirror 5. Then, the light beam from the subject reflected by the quick return mirror 5 forms an image on the finder screen 11 disposed on a surface optically equivalent to the image sensor 7. The light beam from the imaged subject passes through the penta roof prism 12, passes through the eyepiece lens 14, and then travels to the viewfinder 17.

  A part of the light beam that has passed through the penta roof prism 12 passes through the area sensor re-imaging optical system 13 and forms an image on the area sensor 16.

  The area sensor 16 is composed of a CMOS image sensor or the like. The area sensor 16 divides the photographing screen into a plurality of regions and outputs an output signal corresponding to the luminance for each region in order to calculate the exposure value at the time of photographing.

  The imaging element 7 is provided on the camera body 1 on the optical axis OA and at a position that is a planned focal plane of the imaging optical system 3. The focal plane shutter 6 is provided on the front surface thereof. The image sensor 7 is a two-dimensional array of a plurality of photoelectric conversion elements, and is composed of a two-dimensional CCD sensor, a CMOS sensor, or the like.

  The image signal photoelectrically converted by the image sensor 7 is transmitted to the control unit 10 as image data. This image data is subjected to image processing by the control unit 10 and stored in an internal memory (not shown). Note that the memory for storing the captured image data includes a built-in memory, a card-type memory, and the like.

The storage unit 9 stores various data including a control program.
The control unit 10 is configured by a microprocessor, and comprehensively controls operations of the lens unit 2, the finder optical system 20, the area sensor 16, and the like based on an operation control program stored in the storage unit 9. Further, the control unit 10 performs exposure control on the image photographed by the image sensor 7 based on the exposure control program stored in the storage unit 9.

  The control unit 10 has a function as an acquisition unit that acquires the second optical data after acquiring the first optical data transmitted from the lens unit 2.

  The first optical data is data that is acquired first when moving image shooting (including through-image shooting) is started. The control unit 10 acquires the first optical data after at least one of the first photographing and the second photographing described later is started. The second optical data is still image data acquired after the first optical data is acquired, and is updated at a predetermined cycle (see S111 in FIG. 3 described later).

  In the present embodiment, the first optical data and the second optical data are data corresponding to the aperture amount of the aperture 4 (hereinafter also simply referred to as “optical data”). The optical data changes according to at least one of the movement of the zoom lens group, the movement of the focus lens group, and the change of the aperture of the diaphragm 4. Note that the opening of the diaphragm 4 is changed by a manual operation of the diaphragm 4 by the user or an auto iris (automatic diaphragm control) function.

  The control unit 10 acquires the first optical data and the second optical data from the lens unit 2 via a camera communication unit (not shown).

  In addition, the control unit 10 has a function as an exposure control unit that performs first exposure control used for the first shooting and second exposure control used for the second shooting.

  In the first exposure control, the control unit 10 acquires the first optical data, performs exposure control using the first optical data, acquires the second optical data, and then uses the second optical data. Control exposure. In the second exposure control, the control unit 10 acquires the first optical data, performs the exposure control using the first optical data, and also acquires the second optical data after acquiring the first optical data. Exposure control is performed using data.

In the present embodiment, the first shooting is a still image shooting. The second shooting is at least one of shooting a moving image and shooting a through image.
Further, the control unit 10 determines at least one of the aperture value of the aperture 4, the gain of the image sensor 7, and the accumulation time.
Note that the still image and moving image (including through image shooting) shooting processing by the control unit 10 will be described in detail later.

  The camera body 1 includes an operation unit 21. The operation unit 21 includes a release switch, a zoom button, and an input switch for the photographer to set various operation modes of the camera body 1.

  For example, when the user presses the release switch, the camera 100 starts a still image shooting operation. When the user operates a live view switch (not shown), the camera 100 starts displaying a through image. When the user presses the release switch halfway to focus while displaying a through image, and further operates a moving image shooting button (not shown), the camera 100 starts moving image shooting.

  In the photographing operation, first, the quick return mirror 5 jumps upward (dotted line). The camera 100 opens the shutter curtain of the focal plane shutter 6, receives the light beam with the image sensor 7, and outputs an image signal.

  The imaging signal is processed by the control unit 10 in the same manner as the output of the area sensor 16. Then, the captured image is displayed on the display unit 8.

  Even in the through image display mode (including moving image shooting), the camera 100 flips the quick return mirror 5 upward. Then, the camera 100 opens the focal plane shutter 6 and the image sensor 7 receives the light beam from the subject. The output of the image sensor 7 is processed by the control unit 10 and displayed on the display unit 8 as a through image.

  Next, a flow of still image and moving image (including through images) shooting processing in the present embodiment will be described. 2 and 3 are flowcharts showing the basic operation of the still image and moving image shooting process in the camera 100. FIG. FIG. 4 is a conceptual diagram for explaining divided areas of the image sensor 7.

  When the user operates a live view switch (not shown) in the camera 100 that is turned on, the quick return mirror 5 jumps upward, the focal plane shutter 6 opens, and the object from the object incident from the imaging optical system 3 is opened. The light beam is guided to the image sensor 7.

  In S101 illustrated in FIG. 2, the control unit 10 acquires first optical data from the lens unit 2. The first optical data is data acquired first after the power is turned on.

  In S102, the control unit 10 controls the image sensor 7 to accumulate images. In the initial accumulation when the power is turned on, AV (APEX value of the aperture value of the imaging optical system 3), TV (APEX value at the shutter speed), and SV (APEX value of the imaging sensitivity) used for exposure control are fixed values. For example, AV = 5, TV = 6, and SV = 5. The image stored in S102 is transmitted to the control unit 10 as image data.

  In S103, the control unit 10 calculates an evaluation value for photometry based on the image data acquired in S102. In the present embodiment, the evaluation area of the image sensor 7 is divided into 5 × 5 blocks (divided areas) as shown in FIG. 4.

The output of each divided region is represented as Y [i] [j] using coordinates (i, j). The evaluation value of each divided area is obtained by adding the Y output of each pixel of the image sensor 7 within the range of the divided area.
YC [i] [j] = ΣΣY [X] [Y] (Formula 1)

  In equation (1), YC [i] [j] is the output of the evaluation value in each divided region in FIG. Y [X] [Y] is a Y output value at the coordinates X, Y of the image sensor 7, and takes a value of 0 to 4095, for example. The two Σ ranges are the coordinate ranges of all the pixels constituting one evaluation value. For example, when the number of pixels of the image sensor 7 is 2400 × 1600, one evaluation value is 480 × 320 pixels. If i is 0 and j is 0, the range of Σ is 0 to 479 for X and 0 to 319 for Y.

In S104, the control unit 10 corrects the peripheral light reduction (light amount reduction) generated in the imaging optical system 3 with respect to the photometric evaluation value.
YCZ [i] [j] = YC [i] [j] × Z [r] (Formula 2)

  In Equation 2, Z [r] is a correction value determined based on the first optical data acquired in S101. r is the distance between the center of the evaluation value specified by the coordinates of i and j and the center of the optical axis on the imaging surface.

In S105, the control unit 10 calculates a moving image control photometric value BVTh as a moving image photometric calculation based on the output of the photometric evaluation value obtained by correcting the peripheral light reduction.
BVTh = Log2 ((ΣΣYC [i] [j]) / 24) +
BVCONST-AV (Formula 3)

  In Expression 3, Log2 () is a function that returns a logarithmic value of an argument with a base of 2. BVCONST is a value determined by the accumulation time and imaging sensitivity. AV is the first optical data (APEX value) acquired in S101, and is the actual control aperture value of the imaging optical system 3.

In S106, the control unit 10 calculates the photometric value BVIMG for still image control based on the output of the photometric evaluation value corrected for peripheral light reduction as the photometric calculation for still image.
BVIMG =
Log2 ((ΣΣYCZ [i] [j]) / 24) +
BVCONSTIMMG-AVREAL (Formula 4)

  In Equation 4, BVCONSIMMG is a value determined by the aperture value, the accumulation time, and the imaging sensitivity when acquiring image data. AVREAL is the first optical data acquired in S101 or the second optical data (APEX value) updated in S111 (described later), and is the actual control aperture value of the imaging optical system 3.

In S107, the control unit 10 determines the accumulation time TV (APEX value) and gain SV (APEX value) of the image sensor 7 based on the moving image control photometric value BVTh calculated in S105 as the exposure condition for the through image. decide.
TV = 6 (Formula 5)
SV = AV + TV−BVTh (Formula 6)

  Based on the accumulation time TV and the gain SV determined by the expressions 5 and 6, exposure control of the through image is performed. In the through image exposure control, the aperture 4 of the lens unit 2 is not moved, and the aperture value is maintained when the power is turned on.

  In S108, the control unit 10 causes the display unit 8 to display the through image whose exposure has been controlled in S107.

  In S109 illustrated in FIG. 3, the control unit 10 determines whether or not the user has performed a moving image shooting start operation. If NO, the process proceeds to S110. Moreover, if the determination of S109 is YES, the control unit 10 proceeds to the process of S117.

  In S110, the control unit 10 determines whether or not a change in optical data has occurred. As described above, the optical data changes according to at least one of the movement of the zoom lens group, the movement of the focus lens group, and the change of the aperture of the diaphragm 4. If the determination in S110 is YES, the control unit 10 proceeds to the process in S111. Moreover, if the determination of S110 is NO, the control unit 10 proceeds to the process of S112.

  In S111, the control unit 10 re-acquires the second optical data from the lens unit 2 and updates AVREAL (actual control aperture value) used in Expression 4.

  In S112, the control unit 10 determines whether or not the release switch is pressed (ON). If YES, the process proceeds to S113. If the determination in S112 is NO, the control unit 10 proceeds to the process in S116.

In S113, the control unit 10 determines the accumulation time TV (APEX value) and gain SV (APEX value) of the image sensor 7 as exposure conditions for still images.
AV = actual control aperture value (APEX value) of the imaging optical system 3 (Expression 7)
TV = 6 (Expression 8)
SV = AV + TV−BVIMG (Formula 9)

  In S <b> 114, the control unit 10 accumulates still images by the image sensor 7 based on the still image exposure conditions determined in S <b> 113.

  In S115, the control unit 10 reads out the still image accumulated in S113 from the image sensor 7, performs image processing, and outputs the image data as image data. The image data of the still image is stored in an internal memory (not shown).

  In S116, the control unit 10 determines whether or not the camera 100 is turned off. If YES, the process ends. If the determination in S116 is NO, the control unit 10 returns to S102 (see FIG. 2). As described above, unless the camera 100 is turned off in S116, the processes in S102 to S115 are repeatedly executed.

  On the other hand, in S117 (YES in S109), the control unit 10 starts capturing a moving image by the image sensor 7 based on the through image exposure condition determined in S107.

  In S118, the control unit 10 determines whether or not the user has performed an operation for ending moving image shooting. If YES, the process proceeds to S119. If the determination in S118 is NO, the control unit 10 returns to the process in S118.

  Although not shown in FIG. 3, in this embodiment, a still image may be taken when the release switch is pressed during moving image shooting. That is, after shooting of a moving image is started in S117, whether or not the release switch is pressed is determined in the same manner as in S112 until YES is determined in S118. The same processing as the following is performed to capture and store still images.

  In step S119, the control unit 10 performs a recording process on the captured moving image, and then outputs it as image data of the moving image. The image data of the moving image is stored in an internal memory (not shown). After the end of S119, the control unit 10 proceeds to the process of S116.

According to the camera 100 of the present embodiment described above, the following effects can be obtained.
In the camera 100, exposure control is performed based on the first optical data acquired at the time of shooting a moving image and a through image. Therefore, even when the actual control aperture value of the imaging optical system 3 changes due to movement of the zoom lens group or the like during shooting of a moving image or a through image, the exposure of the moving image or the through image does not change.

  For example, in the case of a lens whose actual control aperture value changes as the zoom lens group moves, if a zoom operation is performed while capturing a through image, the lens is exposed to the through image displayed on the display unit 6 or the captured moving image. Flickering occurs and the image quality decreases. This is because the second optical data transmitted from the lens unit 2 to the camera body 1 is updated at a predetermined control cycle while the focal length of the imaging optical system 3 is continuously changed by the zoom operation. It is. That is, since the actual control aperture value of the imaging optical system 3 changes from the update of the second optical data to the next update, the exposure control is performed based on the previous second optical data. Each time the second optical data is updated, an error from the actual control aperture value at that time is recognized as a change in brightness of the through image displayed on the display unit 6 or the captured moving image. is there.

On the other hand, in the camera 100 of the present embodiment, even if the actual control aperture value of the imaging optical system 3 changes due to the movement of the zoom lens group or the like, based on the first optical data (fixed value) acquired first. Since the exposure control is performed, the exposure of the moving image or the through image does not fluctuate even when the second optical data is updated. Therefore, there is no change in brightness in the through image displayed on the display unit 6 or the captured moving image, and a stable exposure image can be taken (displayed).
Thus, according to the camera 100 of the present embodiment, appropriate exposure control of a through image and a moving image can be performed regardless of changes in optical data.

The present invention is not limited to the embodiment described above, and various modifications and changes as shown below are possible, and these are also within the scope of the present invention.
In the present embodiment, the example in which the imaging apparatus according to the present invention is applied to a digital single-lens reflex camera has been described. The imaging apparatus according to the present invention is not limited to this, and can also be applied to a mirrorless single-lens camera that does not include a quick return mirror, a finder optical system, and the like.

  Moreover, although the said embodiment and modification can be used in combination suitably, since the structure of each embodiment is clear by illustration and description, detailed description is abbreviate | omitted. Furthermore, the present invention is not limited by the embodiment described above.

  1: camera body, 2: lens unit, 3: imaging optical system, 4: aperture, 7: imaging device, 8: display unit, 9: storage unit, 10: control unit, 18: mount unit, 100: camera

Claims (6)

An imaging unit that captures an image by an optical system and outputs a signal ;
An acquisition unit for acquiring first optical data and second optical data of the optical system;
When shooting a moving image by the image pickup unit, exposing control was carried out using the first optical data even aperture of the optical system is changed after obtaining the first optical data, still image by the image pickup unit When Ru and Ta Kagesu performs exposure control using the pre-Symbol second optical data that is different from the optical system of the aperture value is changed to the first optical data after acquiring the first optical data A control unit;
An imaging apparatus comprising: The imaging apparatus according to claim 1,
Wherein the first optical data and the second optical data, an image pickup apparatus that is information relating to aperture value of the aperture of the optical system. The imaging apparatus according to claim 1 or claim 2,
Wherein the first optical data and the second optical data, movement of the zoom optical system, the movement of the focus optical system, and an imaging device that varies in response to at least one of the change in the aperture of the diaphragm. In the imaging device according to any one of claims 1 to 3,
The image pickup apparatus, wherein the first optical data includes information relating to peripheral dimming of the optical system. The imaging apparatus according to claim 4,
The control unit calculates an evaluation value from a signal output from the imaging unit and a correction value determined by information on the peripheral light reduction, the calculated evaluation value, the first optical data, and the first optical data An imaging device that performs exposure control based on any one of two optical data. In the imaging device according to any one of claims 1 to 5,
The acquisition unit is an imaging device that periodically acquires the second optical data.

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