JP2010200097A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of certainly and easily performing a valve shutter photographing for a user. <P>SOLUTION: The imaging apparatus includes: a photographing optical system 102 or the like, in which a digital single-lens reflex camera 110 carries out an image-formation of an object image by an incident light from an object; an image sensor 116 which outputs pixel signals according to the incident light; an image sensor 116 which adds the pixel signals and outputs an addition result; an evaluation section 303 which calculates a luminance of the addition result and outputs a calculation result; an indicator 400 which displays the calculation result; and a liquid crystal panel 119 which displays the object image based on the addition result. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an imaging apparatus that performs bulb shutter photography.

  Digital single-lens reflex cameras that support bulb shutter photography are widely used in Japan and overseas. In bulb shutter photography, the digital single-lens reflex camera keeps releasing the shutter while the release button is pressed by the user, and closes the shutter when the release button is released from the pressing operation (hereinafter referred to as release operation). Then, take a picture with a long exposure of several seconds to several minutes.

  Examples of bulb shutter photography include a moonlight photograph of a landscape exposed with moonlight, a photograph of the headlight trajectory of a vehicle traveling at night, an astronomical photograph of a night sky star trajectory, etc. As these examples show, there is a wide demand for bulb shutter photography that can provide fantastic images.

  However, in bulb shutter photography, the user adjusts the shutter opening time by pressing the release button, so it is necessary to adjust the exposure time according to the brightness of the subject. For example, a moonlight photograph has a problem that if the exposure time is too long, the pixels are saturated, resulting in a so-called overexposed subject image, and if the exposure time is too short, the entire subject image is dark.

  In this way, in bulb shutter photography, it is necessary to calculate the optimal exposure time, and since the brightness of the subject can also change during the exposure time of several minutes, fine adjustment of the exposure time is also necessary, and bulb shutter photography is successful. Requires advanced knowledge. Therefore, it is expected to realize a digital single-lens reflex camera that can perform bulb shutter photography reliably and easily for the user.

  Conventional digital single-lens reflex cameras add the subject image data during shooting to prevent bulb shutter shooting failure, and display the exposure status of the subject image on a display device (such as a liquid crystal panel or electronic viewfinder). It was. As a result, the user can adjust the shutter opening time while checking the exposure state during shooting (see, for example, Patent Document 1).

JP 2003-69897 A

  However, display devices such as a liquid crystal panel and an electronic viewfinder provided in a digital single lens reflex camera often have a low resolution and a rough color tone that can be displayed. For this reason, the user cannot confirm the detailed exposure state of the subject image during shooting, and even if, for example, pixels in a narrow area are saturated and overexposure occurs during shooting, this is not possible during bulb shutter shooting. I did not notice.

  In this case, even if the user notices that the overexposure has occurred in the subject image after taking the bulb shutter, the overexposure is a portion where the pixels are saturated, and thus complete image correction cannot be performed after the taking. For this reason, there is a case where the user needs to redo the shooting or cannot take the shot again because the timing is missed.

  The present invention has been made in view of the above-described points, and an object of the present invention is to provide an imaging apparatus that can reliably and easily perform bulb shutter photography.

  The present invention has been made to solve the above problems, an optical unit that forms a subject image with incident light from a subject, an imaging unit that outputs a pixel signal in accordance with the incident light, and An addition unit that temporally adds pixel signals and outputs the addition result; an evaluation unit that calculates the luminance of the addition result; and outputs the calculation result; and a luminance display unit that displays the calculation result. An imaging device characterized by the above.

  The present invention is the imaging apparatus, wherein the adding unit is a pixel provided in the imaging unit.

  Further, the present invention is the imaging apparatus, wherein the evaluation unit calculates a contrast based on the addition result, and causes the luminance display unit to display the contrast.

  Further, the present invention is the imaging apparatus, wherein the evaluation unit calculates a histogram based on the addition result, and causes the luminance display unit to display the histogram.

  Further, the present invention is characterized in that the evaluation unit determines the exposure state, and when the minimum luminance value is equal to or higher than a predetermined threshold value, or when there is no luminance less than the predetermined threshold value, the photographing is ended. It is an imaging device.

  In addition, the present invention is an imaging apparatus including an operation unit that receives a user's operation input and acquires the threshold value by the operation input.

  In addition, the present invention is an imaging apparatus including a subject image display unit that displays the subject image based on the addition result.

  According to the present invention, since the imaging device notifies the user of the exposure state by an indicator or a liquid crystal panel display during bulb shutter photography, the imaging device can perform bulb shutter photography reliably and easily for the user.

  In addition, the imaging apparatus determines the exposure state during bulb shutter photography, and the imaging apparatus ends photographing when a preset exposure condition is satisfied. Therefore, the imaging apparatus performs bulb shutter photography reliably and easily for the user. be able to.

It is the figure which showed the structure of the digital single-lens reflex camera (imaging device) of the 1st Embodiment of this invention. It is the figure which showed the slide operation | movement of the focal plane shutter in bulb shutter photography. It is the flowchart which showed the operation | movement procedure of the digital single-lens reflex camera (imaging apparatus) in the valve shutter imaging | photography using the image sensor read nondestructively. It is the figure which showed the indicator display and the warning display in bulb shutter photographing. It is the figure which showed the histogram display in bulb shutter photography. It is the figure which showed the structure of the digital single-lens reflex camera (imaging device) of the 2nd Embodiment of this invention. It is the flowchart which showed the operation | movement procedure of the digital single-lens reflex camera (imaging device) in the valve shutter imaging | photography using the image sensor read destructively.

[First embodiment]
A first embodiment for carrying out the present invention will be described. FIG. 1 is a diagram illustrating a configuration of a digital single-lens reflex camera (imaging device) according to a first embodiment of the present invention. The digital single lens reflex camera 110 includes an interchangeable lens housing 101, a main mirror 111, a focusing screen 112, a pentaprism 113, an eyepiece lens 114, a focal plane shutter 115, an image sensor 116, an SDRAM 118, and a liquid crystal. Panel 119, release button 120, memory card 121, optical finder 123, control unit 301, reading unit 302, SDRAM interface 305, memory interface 307, driver 306, system bus 308, image processing A unit 309 and an indicator 400.

  The interchangeable lens housing 101 includes a photographing optical system 102. The photographing optical system 102 includes a plurality of lenses, moves in the optical axis direction according to the control of the control unit 301, and collects incident light from a subject (not shown). The photographing optical system 102 forms a subject image on the image sensor 116 or the focusing screen 112.

  The continuous image display in which the captured image is repeatedly displayed is hereinafter referred to as a live view. The main mirror 111 disposed on the optical axis reflects incident light. The main mirror 111 is disposed on the optical axis, and retracts from the optical axis by rotating according to the control of the control unit 301 (hereinafter referred to as an up state). The main mirror 111 is brought into an up state during photographing or live view.

  The main mirror 111 in the up state does not block incident light from the photographing optical system 102. In this case, the subject image is formed on the focal plane shutter 115 or the image sensor 116. On the other hand, the main mirror 111 that is not in the up state reflects incident light and forms a subject image on the focusing screen 112.

  The focusing screen 112 projects a subject image on the focusing screen 112. The pentaprism 113 inverts the subject image displayed on the focusing screen 112 and makes it enter the eyepiece 114 as an upright subject image.

  The eyepiece 114 enlarges the subject image and causes the optical viewfinder 123 to form the subject image. As a result, the user can visually recognize the subject image through the optical viewfinder 123.

  The focal plane shutter 115 includes a front curtain 124 and a rear curtain 125. The focal plane shutter 115 slides the front curtain 124 and the rear curtain 125 independently under the control of the control unit 301. The front curtain 124 slides to block incident light from the photographing optical system 102. The same applies to the trailing curtain 125. The sliding operation of the front curtain 124 and the rear curtain 125 will be described later with reference to FIG.

  The image sensor 116 includes a transistor circuit (not shown) including a capacitor (not shown) and a plurality of pixels (not shown) arranged two-dimensionally. A pixel (not shown) included in the image sensor 116 generates a charge corresponding to the amount of incident light and outputs a pixel signal.

  A capacitor (not shown) included in the image sensor 116 resets the charge generated in the pixel (not shown) when the readout unit 302 performs a reset operation.

  The image sensor 116 is, for example, a CMOS sensor, and can hold the charge as it is even if a pixel signal is output from the pixel (hereinafter referred to as non-destructive reading). Therefore, the pixels (not shown) of the image sensor 116 continue to store the charges generated in the pixels by opening the focal plane shutter 115 even after outputting the pixel signal. Here, it is assumed that the reading unit 302 does not reset the capacitor (not shown) while the focal plane shutter 115 is opened. For this reason, in the image sensor 116, the opening time of the focal plane shutter 115 is equal to the exposure time of the pixels.

  The release button 120 accepts a pressing operation by the user and outputs a pressing operation signal to the control unit 301. The release button 120 receives a release operation by the user and outputs a release operation signal indicating the end of the release operation to the control unit 301.

  The control unit 301 notifies the reading unit 302 of a predetermined reading cycle setting value that is a cycle in which the reading unit 302 reads pixel signals. The control unit 301 instructs the focal plane shutter 115 to slide the front curtain 124 and the rear curtain 125. When notified of the pressing operation signal, the control unit 301 brings the main mirror 111 into the up state.

  On the other hand, when a release operation signal indicating the end of the release operation is notified and the trailing curtain 125 finishes the slide operation, the control unit 301 returns the main mirror 111 to the optical axis. Further, the control unit 301 instructs the image processing unit 309 to output subject image data to the memory card interface 307.

  The reading unit 302 generates a horizontal synchronizing signal and a vertical synchronizing signal according to the reading cycle setting value notified from the control unit 301, and reads a pixel signal from the image sensor 116 in synchronization with these synchronizing signals. The reading unit 302 performs AD conversion on the read pixel signal, and outputs the pixel signal after AD conversion to the SDRAM 118 via the system bus 308 and the SDRAM interface 305.

  The system bus 308 is a data transmission path. The SDRAM interface 305 converts the format of the pixel signal after AD conversion and stores it in the SDRAM 118 as pixel signal data. The SDRAM 118 stores pixel signal data.

  The image processing unit 309 is controlled by the control unit 301 to acquire pixel signal data stored in the SDRAM 118 and perform image processing. Here, image processing refers to conversion into a format recorded on a memory card (for example, JPEG (Joint Photographic Experts Group) format), and pixel signal data indicates that the larger the value, the higher the luminance. . The image processing unit 309 includes an evaluation unit 303. The evaluation unit 303 acquires a plurality of pixel signal data stored in the SDRAM 118, and calculates the following image characteristics of the subject image data based on the pixel signal data.

  The evaluation unit 303 calculates the contrast of the subject image data. Here, the contrast is the difference between the minimum luminance and the maximum luminance, that is, the difference between the minimum value of the pixel signal data and the maximum value of the pixel signal data.

  The evaluation unit 303 calculates a histogram of the subject image data. Here, the histogram is a graph showing the distribution of the number of pixels according to the luminance by taking the luminance on the horizontal axis and the number of pixels on the vertical axis. The evaluation unit 303 generates a histogram display, and the image processing unit 309 superimposes it on the subject image data. Note that the evaluation unit 303 may calculate various image characteristics other than these.

  The evaluation unit 303 outputs the evaluation data including the contrast calculation result and the histogram calculation result, and the subject image data to the driver 306. When receiving an instruction from the control unit 301, the image processing unit 309 outputs subject image data to the memory card interface 307.

  Here, it is assumed that pixel signal data that is equal to or greater than a predetermined overexposure threshold is overexposed pixel signal data. Further, it is assumed that pixel signal data that is equal to or less than a predetermined blackout threshold value is blackened pixel signal data. The evaluation unit 303 replaces the pixel signal data that exceeds the overexposure threshold with pixel signal data indicating a warning color (for example, red, zebra pattern, etc.), and outputs it as subject image data. The warning color display will be described later with reference to FIG.

  The driver 306 acquires subject image data, converts it into a data format used by the liquid crystal panel 119, and outputs it to the liquid crystal panel 119. The driver 306 acquires evaluation data, converts it into a data format used by the indicator 400, and outputs it to the indicator 400.

  The liquid crystal panel 119 acquires subject image data and displays the subject image. The indicator 400 acquires evaluation data and displays a calculation result included in the evaluation data. The display of the calculation result will be described later with reference to FIGS. Note that these calculation results may be superimposed on the liquid crystal panel 119.

  The memory card interface 307 stores the image data (subject image data) generated by the image processing unit 309 in the memory card 121. The memory card 121 is a so-called flash medium, for example, and stores subject image data. The memory card 121 may be a storage medium that can be detached from the digital single-lens reflex camera 110. The memory card 121 may store the evaluation data output from the evaluation unit 303.

  FIG. 2 is a diagram showing a sliding operation of the focal plane shutter 115 in bulb shutter photography. In the state before the bulb shutter photographing shown in FIG. 2A, the front curtain 124 is completely closed and the rear curtain 125 is completely opened. The completely closed front curtain 124 completely blocks incident light, and does not form a subject image on the image sensor 116.

  Next, it is assumed that the control unit 301 is notified of a pressing operation signal from the release button 120. The control unit 301 completely opens the front curtain 124 by controlling the focal plane shutter 115 (FIG. 2B). Since the rear curtain 125 remains open, the image sensor 116 is exposed so as not to block incident light from the photographing optical system 102. In this way, the subject image is formed on the image sensor 116.

  Next, it is assumed that the control unit 301 is notified of a release operation signal from the release button 120. The control unit 301 completely closes the trailing curtain 125 by controlling the focal plane shutter 115 (FIG. 2C). The fully closed rear curtain 125 completely blocks the incident light and prevents the image sensor 116 from forming a subject image.

  Next, the control unit 301 controls the focal plane shutter 115 to return the front curtain 124 and the rear curtain 125 to the state before the bulb shutter photography (FIG. 2A). In bulb shutter photography, the subject image is exposed to the image sensor 116 in this way.

  FIG. 3 is a flowchart showing an operation procedure of the digital single-lens reflex camera (imaging device) in bulb shutter photography using an image sensor that is read nondestructively. In bulb shutter photography, the control unit 301 waits for a pressing operation signal from the release button 120. Here, it is assumed that the release button 120 receives a pressing operation by the user and outputs a pressing operation signal (step S1).

  When notified of the pressing operation signal, the control unit 301 brings the main mirror 111 into the up state. The control unit 301 controls the focal plane shutter 115. As a result, the front curtain 124 is completely opened and the rear curtain 125 is also completely opened (step S2).

  Next, the control unit 301 notifies the reading unit 302 of the reading cycle setting value. The reading unit 302 generates a horizontal synchronizing signal and a vertical synchronizing signal according to the reading cycle setting value notified from the control unit 301, and reads a pixel signal from the image sensor 116 in synchronization with these synchronizing signals. The reading unit 302 performs AD conversion on the read pixel signal, and outputs the pixel signal after AD conversion to the SDRAM 118 via the system bus 308 and the SDRAM interface 305 (step S3).

  Next, the image processing unit 309 acquires pixel signal data stored in the SDRAM 118, performs image processing, generates subject image data to be displayed on the liquid crystal panel 119, and writes it back to the SDRAM 118. The evaluation unit 303 calculates the contrast and histogram of the subject image data, and stores the calculation result in the SDRAM 118. Note that the subject image data on which the evaluation result is superimposed may be stored in the SDRAM 118 (step S4).

  Next, the driver 306 acquires subject image data, converts it into a data format used by the liquid crystal panel 119, and outputs it to the liquid crystal panel 119. The driver 306 acquires evaluation data, converts it into a data format used by the indicator 400, and outputs it to the indicator 400.

  On the other hand, the liquid crystal panel 119 acquires subject image data and displays the subject image. Here, a histogram may be superimposed on the subject image data. The indicator 400 acquires evaluation data and displays the calculation result included in the evaluation data (step S5).

  Next, the control unit 301 waits for a release operation signal from the release button 120. When the release operation signal is not notified, the control unit 301 returns to step S3. When notified of the release operation signal, the control unit 301 proceeds to step S7 (step S6).

  When notified of the release operation signal, the controller 301 returns the main mirror 111 to the optical axis. The control unit 301 notified of the release operation signal controls the focal plane shutter 115. As a result, the front curtain 124 is completely opened and the rear curtain 125 is completely closed. Next, the front curtain 124 and the rear curtain 125 return to the state before the bulb shutter photography (step S7).

  When notified of the release operation signal, the control unit 301 instructs the evaluation unit 303 to output subject image data to the memory card interface 307. The memory card interface 307 converts the subject image data into a data format used by the memory card 121 and stores it in the memory card 121 (step S8).

  Next, display of calculation results will be described. FIG. 4 is a diagram showing an indicator display and a warning display in bulb shutter photography. In FIG. 4, it is assumed that a subject image (night sky) 410, a subject image (crescent moon) 411, and a subject image (mountain) 412 are displayed as subject images on the liquid crystal panel 119. The indicator 400 is disposed close to the liquid crystal panel 119 and has a whiteout range 401, a whiteout warning range 402, an optimum exposure range 403, an intermediate exposure range 404, a blackout warning range 405, and a blackout range. 406 and a contrast display bar 407 are displayed.

  Each range of the indicator 400 is a range distinguished in advance by a predetermined threshold. For example, the whiteout range 401 and the whiteout warning range 402 are distinguished by a predetermined whiteout threshold value determined in advance. Further, the blackout warning range 405 and the blackout range 406 are distinguished by a predetermined blackout threshold value determined in advance. The indicator 400 displays each range based on each threshold value.

  The contrast of the subject image data is represented by a contrast display bar 407. The upper end of the contrast display bar 407 represents the highest luminance among the plurality of pixel signal data, that is, the maximum value among the plurality of pixel signal data. The lower end represents the lowest luminance among the plurality of pixel signal data, that is, the minimum value among the plurality of pixel signal data. The indicator 400 displays the contrast display bar 407 based on the maximum value and the minimum value of the pixel signal data included in the acquired evaluation data.

  FIG. 4A shows a state in which exposure is not yet sufficient immediately after the start of bulb shutter photography, and the display on the liquid crystal panel 119 is dark overall. Therefore, it is assumed that the upper end of the contrast display bar 407 is at the boundary between the blackout warning range 405 and the intermediate exposure range 404, and the lower end of the contrast display bar 407 is in the blackout range 406.

  FIG. 4B is a diagram illustrating that an optimum exposure state has been reached after a predetermined time has elapsed since the start of bulb shutter photography. Therefore, the upper end of the contrast display bar 407 is in the optimum exposure range 403, and the lower end of the contrast display bar 407 is in the intermediate exposure range 404. If the release button 120 accepts the release operation by the user in this state, the control unit 301 is notified of the release operation signal and controls the focal plane shutter 115, so that the subject image data without overexposure or underexposure is obtained. Is stored in the memory card 121 as described above, and bulb shutter photography is terminated.

  FIG. 4C is a diagram illustrating that a long time has elapsed from the start of bulb shutter photography, and the charge of the pixel indicating the subject image (crescent moon) 411 is close to saturation. For this reason, the upper end of the contrast display bar 407 indicates a subject image (a crescent moon) 411 in the overexposure warning range 402. It is assumed that the lower end of the contrast display bar 407 is in the intermediate exposure range 404. The evaluation unit 303 replaces the subject image (crescent moon) 411 in the overexposure warning range 402 with a warning color (for example, red, zebra pattern, etc.) and outputs it as subject image data. Therefore, the subject image (crescent moon) 411 is displayed on the liquid crystal panel 119 with a warning color.

  FIG. 5 is a diagram showing a histogram display in bulb shutter photography. As described above, the histogram 507 is a graph showing the distribution of the number of pixels according to the luminance by taking the luminance on the horizontal axis and the number of pixels on the vertical axis. Further, each range of the histogram display range 500 is a range that is distinguished in advance by a predetermined threshold value. That is, the histogram display range 500 can display the distribution of the number of pixels according to the luminance in addition to the information displayed on the indicator 400. The histogram display range 500 is superimposed on the liquid crystal panel 119. The histogram display range 500 may be displayed on the indicator 400. The histogram 507 may take the luminance on the vertical axis and the number of pixels on the horizontal axis.

  As described above, according to the embodiment of the present invention, the digital single-lens reflex camera 110 notifies the user of the exposure state by the display of the indicator 400 or the liquid crystal panel 119 during the bulb shutter photographing. Bulb shutter photography can be easily performed.

  Note that the controller 301 may determine the exposure state during bulb shutter photography. In this case, if the preset exposure condition is satisfied, the control unit 301 may end the shooting without using the release operation signal. For example, when the minimum value of the pixel signal data is equal to or greater than a predetermined threshold, or when there is no pixel signal data that does not satisfy the predetermined threshold, the evaluation unit 303 sets the minimum pixel signal data. The control unit 301 is notified of the value and the maximum value of the pixel signal data. The control unit 301 compares the pixel signal data with a predetermined threshold value indicating the exposure condition. When the exposure condition is satisfied, the control unit 301 ends the shooting according to the above procedure regardless of the release operation signal. Here, the exposure condition may be input to the control unit 301 from an operation unit (not shown in FIG. 1).

[Second Embodiment]
A second embodiment for carrying out the present invention will be described. FIG. 6 is a diagram showing a configuration of a digital single-lens reflex camera (imaging device) according to the second embodiment of the present invention. The digital single lens reflex camera 100 includes an operation unit 122 and an addition unit 304 in addition to the configuration of the digital single lens reflex camera 110 of the first embodiment. Further, the digital single-lens reflex camera 100 includes an image sensor 126 instead of the image sensor 116 of the first embodiment.

  The operation unit 122 receives a setting operation by the user, and notifies the control unit 301 of a reading cycle setting value that is a cycle in which the reading unit 302 reads a pixel signal. The control unit 301 notifies the reading unit 302 of the read cycle setting value notified from the operation unit 122. Note that the operation unit 122 may accept input of a set value other than the read cycle set value, for example, a threshold value indicating an exposure condition.

  The image sensor 126 includes a transistor circuit (not shown) including a capacitor (not shown) and a plurality of pixels (not shown) arranged two-dimensionally. A pixel (not shown) included in the image sensor 126 outputs a pixel signal by generating a charge corresponding to the amount of incident light.

  A capacitor (not shown) included in the image sensor 126 resets a charge generated in a pixel (not shown) when the readout unit 302 performs a reset operation. The reading unit 302 resets a capacitor (not shown) at a reading cycle determined by a reading cycle setting value while the focal plane shutter 115 is opened.

  The image sensor 126 is, for example, a CCD sensor, and when the pixel signal is output from the pixel, the charge cannot be held in the pixel as it is (hereinafter referred to as destructive reading). Therefore, the reading unit 302 performs a reset operation of a capacitor (not shown) while the focal plane shutter 115 is opened after destructively reading out the pixel signal at a reading cycle determined by the reading cycle setting value. For this reason, in the image sensor 126, the readout cycle and the pixel exposure time are equal. Here, when the reading unit setting value is not notified from the operation unit 122, the control unit 301 may notify the reading unit 302 of a predetermined reading cycle setting value stored as an initial value in advance.

  The reading unit 302 generates a horizontal synchronizing signal and a vertical synchronizing signal according to the reading cycle setting value notified from the control unit 301, and reads a pixel signal from the image sensor 116 in synchronization with these synchronizing signals. The reading unit 302 resets a capacitor (not shown) at a reading cycle determined by a reading cycle setting value while the focal plane shutter 115 is opened. The reading unit 302 performs AD conversion on the read pixel signal, and outputs the pixel signal after AD conversion to the SDRAM 118 via the system bus 308 and the SDRAM interface 305.

  The image processing unit 309 is controlled by the control unit 301 to acquire pixel signal data stored in the SDRAM 118 and perform image processing. Here, the pixel signal data indicates that the larger the value, the higher the luminance.

  As described above, when the pixel signal is output from the pixel, the image sensor 126 cannot hold the charge in the pixel as it is. For this reason, the image processing unit 309 includes an addition unit 304 in addition to the evaluation unit 303. The adder 304 acquires the pixel signal data stored in the SDRAM 118, and cumulatively adds the pixel signal data output from the same pixel a plurality of times to generate subject image data.

  The evaluation unit 303 evaluates the subject image data that has been subjected to cumulative addition processing, and calculates contrast, a histogram, and the like, as in the first embodiment. The operation of other blocks is the same as that of the first embodiment.

  FIG. 7 is a flowchart showing an operation procedure of the digital single-lens reflex camera (imaging device) in bulb shutter photography using an image sensor that is read by destructive reading. In bulb shutter photography, the control unit 301 waits for a pressing operation signal from the release button 120. Here, it is assumed that the release button 120 receives a pressing operation by the user and outputs a pressing operation signal (step Sa1).

  When notified of the pressing operation signal, the control unit 301 notifies the reading unit 302 of the read cycle setting value. Note that the read cycle setting value may be a predetermined setting value or a setting value input from the operation unit 122 (step Sa2).

  Next, the control unit 301 brings the main mirror 111 into an up state. The control unit 301 controls the focal plane shutter 115. As a result, the front curtain 124 is completely opened. Also, the trailing curtain 125 remains completely open (step Sa3).

  The reading unit 302 generates a horizontal synchronizing signal and a vertical synchronizing signal according to the reading cycle setting value notified from the control unit 301, and reads a pixel signal from the image sensor 116 in synchronization with these synchronizing signals. Further, the reading unit 302 resets a capacitor (not shown). The reading unit 302 performs AD conversion on the read pixel signal, and outputs the pixel signal after AD conversion to the SDRAM 118 via the system bus 308 and the SDRAM interface 305 (step Sa4).

  Next, the adding unit 304 acquires the pixel signal data stored in the SDRAM 118, and cumulatively adds the pixel signal data output a plurality of times from the same pixel (step Sa5).

  The image processing unit 309 acquires a plurality of pixel signal data subjected to cumulative addition processing, and subjects the pixel signal data to image processing, thereby creating subject image data to be displayed. Here, the evaluation unit 303 superimposes a histogram on the subject image data. The driver 306 acquires subject image data, converts it into a data format used by the liquid crystal panel 119, and outputs it to the liquid crystal panel 119. The liquid crystal panel 119 acquires subject image data and displays the subject image.

  On the other hand, the driver 306 acquires evaluation data, converts it into a data format used by the indicator 400, and outputs it to the indicator 400. The indicator 400 acquires evaluation data and displays the calculation result included in the evaluation data (step Sa6).

  Next, the control unit 301 waits for a release operation signal from the release button 120. When notified of the release operation signal, the control unit 301 returns to step S3. On the other hand, when notified of the release operation signal, the control unit 301 proceeds to step Sa8 (step Sa7).

  Next, it is assumed that the release button 120 outputs a release operation signal. When notified of the release operation signal, the controller 301 returns the main mirror 111 to the optical axis. Further, the control unit 301 controls the focal plane shutter 115. As a result, the front curtain 124 is completely opened and the rear curtain 125 is completely closed. Thereafter, the front curtain 124 and the rear curtain 125 return to the state before the bulb shutter photography.

  The control unit 301 instructs the image processing unit 309 to output subject image data to the memory card interface 307. The memory card interface 307 converts the subject image data into a data format used by the memory card 121 and stores it in the memory card 121 (step Sa8).

  As described above, according to the embodiment of the present invention, the digital single-lens reflex camera 110 notifies the user of the exposure state by the display of the indicator 400 or the liquid crystal panel 119 during the bulb shutter photographing. Bulb shutter photography can be easily performed. Note that, as described above, the control unit 301 may determine the exposure state during bulb shutter shooting, and may end shooting in the above-described procedure regardless of the release operation signal when a preset exposure condition is satisfied.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  For example, the focal plane shutter 115 may be another type of shutter such as an electronic shutter.

  The imaging apparatus according to the present invention corresponds to the digital single-lens reflex camera 100 and the digital single-lens reflex camera 110, and the optical unit includes an interchangeable lens housing 101, a photographing optical system 102, a main mirror 111, and the like. The imaging unit corresponds to a pixel (not shown), the image sensor 116, the image sensor 126, and the reading unit 302, and the adding unit corresponds to the focal plane shutter 115. The evaluation unit corresponds to a pixel (not shown), the image sensor 116, the image sensor 126, and the image processing unit 309. The evaluation unit corresponds to the evaluation unit 303, the control unit 301, and the image processing unit 309. The luminance display unit corresponds to the indicator 400, the liquid crystal panel 119, and the driver 306, and the subject image display unit includes the liquid crystal panel 119, the driver 306, Correspondingly, the operation unit corresponds to the operation unit 122, the pixel corresponds to a pixel (not shown).

  The present invention is suitable for a digital single-lens reflex camera that performs bulb shutter photography.

DESCRIPTION OF SYMBOLS 100 ... Digital single lens reflex camera 101 ... Interchangeable lens housing | casing 102 ... Shooting optical system 110 ... Digital single lens reflex camera 111 ... Main mirror 112 ... Focusing screen 113 ... Pentaprism 114 ... Eyepiece lens 115 ... Focal plane shutter 118 ... SDRAM 119 ... Liquid crystal Panel 120 ... Release button 121 ... Memory card 122 ... Operation unit 123 ... Optical viewfinder 124 ... Front curtain 125 ... Rear curtain 126 ... Image sensor 301 ... Control unit 302 ... Reading unit 303 ... Evaluation unit 304 ... Addition unit 305 ... SDRAM interface 306 ... driver 307 ... memory card interface 308 ... system bus 309 ... image processing unit 400 ... indicator 401 ... whiteout range 402 ... whiteout warning range 403 Optimal exposure range 404 ... Intermediate exposure range 405 ... Blackout warning range 406 ... Blackout range 407 ... Contrast display bar 500 ... Histogram display range 501 ... Overexposure range 502 ... Overexposure warning range 503 ... Optimal exposure range 504 ... Intermediate exposure range 505 ... Blackout warning range 506 ... Blackout range 507 ... Histogram

Claims (7)

An optical unit that forms a subject image with incident light from the subject;
An imaging unit that outputs a pixel signal in response to the incident light;
An adder that temporally adds the pixel signals and outputs an addition result;
An evaluation unit that calculates the luminance of the addition result and outputs the calculation result;
A luminance display unit for displaying the calculation result;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the adding unit is a pixel provided in the imaging unit.   The imaging apparatus according to claim 1, wherein the evaluation unit calculates a contrast based on the addition result, and causes the luminance display unit to display the contrast.   The imaging apparatus according to claim 1, wherein the evaluation unit calculates a histogram based on the addition result, and causes the luminance display unit to display the histogram.   2. The evaluation unit according to claim 1, wherein the evaluation unit determines an exposure state, and terminates photographing when a minimum luminance value is equal to or greater than a predetermined threshold value, or when there is no luminance less than the predetermined threshold value. The imaging device described.   The imaging apparatus according to claim 5, further comprising an operation unit that receives an operation input from a user and acquires the threshold value by the operation input.   The imaging apparatus according to claim 1, further comprising a subject image display unit configured to display the subject image based on the addition result.

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