JP2005037963A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera that exerts exposure control in which auto-focusing is taken into account. <P>SOLUTION: The digital camera includes: a focusing control means which controls the auto-focusing of an optical system; a photometer means which obtains the brightness of a subject from image data obtained by an imaging means during a standby period for photographing; and a diaphragm value setting means which sets the diaphragm value of the optical system based upon the brightness of the subject. When the brightness of the subject is higher than a predetermined reference value, the focusing control means exerts the auto-focusing control, and thereafter the diaphragm value setting means sets the diaphragm value of the optical system to a value higher than that used for auto-focusing control, and the photometer means obtains the brightness of the subject. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for performing exposure control in imaging.

  Conventionally, in a digital camera that acquires image data using an image sensor such as a CCD, exposure is determined by determining an exposure control value such as a shutter speed or an aperture value based on the brightness in the image data acquired in a shooting standby state. It comes to perform control.

  Further, when the digital camera performs automatic optical system focus control, so-called autofocus, a method of driving the optical system based on an evaluation value obtained from image data such as a contrast method is employed. Since the main subject image generally exists in a limited area in the image data, the evaluation value is obtained from a predetermined focus area in the image data.

  By the way, in order to obtain the focus evaluation value as described above, it is necessary to acquire image data. However, in a conventional digital camera, the exposure control value when acquiring this image data is based on the brightness of the entire image data. I was asking.

  For this reason, when the brightness difference between the focus area in the image data and other areas is relatively large, and when the focus area is blacked out, an appropriate focus evaluation value cannot be obtained. There were problems such as a decrease in accuracy and speed.

  That is, in the conventional digital camera, since exposure control and focus control are not linked, various problems have occurred.

  The present invention has been made in view of the above problems, and an object thereof is to provide a technique capable of performing appropriate exposure control in consideration of focus control.

  In order to solve the above-mentioned problems, the invention of claim 1 is a digital camera having an image pickup means for acquiring image data of a subject via an optical system, wherein a predetermined match in the image data acquired by the image pickup means is obtained. Focus control means for performing autofocus control for driving the optical system so that the focus target area is in focus, and a maximum specific gravity of the focus target area in the image data acquired by the imaging means in a shooting standby state As an area, a focus exposure calculation means for deriving a focus exposure control value from the image data, and when the focus control means performs autofocus control, exposure control of the imaging means is performed using the focus exposure control value. Exposure control means for performing

  According to a second aspect of the present invention, in the digital camera according to the first aspect, the recording used by the exposure control unit when acquiring recording image data from the image data acquired by the imaging unit in a shooting standby state. Recording exposure calculation means for deriving the exposure control value for storage, and storage means for holding both the exposure control value for focus and the exposure control value for recording.

  According to a third aspect of the present invention, there is provided a digital camera having an imaging unit that acquires image data of a subject via an optical system, the focus control unit performing autofocus control of the optical system, and the imaging control unit in the shooting standby state. Photometric means for obtaining the brightness of the subject from image data acquired by the imaging means; and aperture value setting means for setting the aperture value of the optical system based on the brightness of the subject. When the brightness is higher than a predetermined reference value, after the focus control unit performs autofocus control, the aperture value setting unit sets the aperture value of the optical system to be larger than the value when performing autofocus control. The light metering means obtains the brightness of the subject.

  According to a fourth aspect of the present invention, there is provided a digital camera having an imaging unit that acquires image data of a subject via an optical system, wherein the optical data is acquired so that the image data acquired by the imaging unit is in a focused state. Focus control means capable of switching a focus control method between auto focus control for driving the system and manual focus control for driving the optical system based on an operation input; and image data acquired by the imaging means Photometric means for determining the brightness of the subject, and aperture value setting means for setting the aperture value of the optical system based on the brightness of the subject, wherein the brightness of the subject is a predetermined reference value If the focus control method of the focus control means is auto focus control, the aperture value setting means In the case of the scan control, and setting by different aperture value of the optical system.

  According to a fifth aspect of the present invention, there is provided an exposure control apparatus for performing exposure control of an image pickup means for acquiring image data of a subject via an optical system, wherein the image data in the image data acquired by the image pickup means in a shooting standby state. A focus exposure calculation means for deriving a focus exposure control value from the image data, with a focus target area used for focus evaluation by a focus control means for performing autofocus control of the optical system as a maximum specific gravity area, When the focus control means performs autofocus control, exposure control of the imaging means is performed using the focus exposure control value.

  According to the first and fifth aspects of the present invention, when the autofocus control is performed, the exposure control is performed using the focus exposure control value based on the focus target area, and therefore the autofocus control is performed quickly and with high accuracy. be able to.

  According to the invention of claim 2, since both the focus exposure control value and the recording exposure control value are held, when the digital camera shifts from the shooting standby operation to the autofocus control operation, or When shifting from the autofocus control operation to the recording image data acquisition operation, it is not necessary to acquire an exposure control value, and the operation can be quickly shifted.

  According to the invention of claim 3, it is preferable to set the aperture value to a relatively small value when performing autofocus control. On the other hand, if the aperture value is a relatively small value, the brightness of the subject is reduced. It cannot be obtained with high accuracy. For this reason, it is possible to obtain the brightness of the subject with high accuracy by setting the aperture value to a relatively large value compared to the case of autofocus control and obtaining the brightness of the subject.

  According to the fourth aspect of the present invention, the aperture value can be set to an appropriate value in both the auto focus control and the manual focus control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<1. First Embodiment>
<1-1. Digital camera configuration>
FIG. 1 to FIG. 3 are diagrams showing the main configuration of the digital camera 1 according to the embodiment of the present invention, and FIG. 1 to FIG. 3 correspond to a front view, a top view, and a rear view, respectively. As shown in FIGS. 1 and 2, the digital camera 1 is mainly composed of a camera body 2 and a photographing lens 3.

  The photographic lens 3 is configured as a zoom lens including a plurality of lens groups, and the photographic magnification (focal length) can be changed by rotating a zoom ring 31 provided on the peripheral edge thereof. The photographing lens 3 is provided with a macro switching lever 32, and the macro photographing can be performed by sliding the macro switching lever 32.

  As shown in FIG. 1, on the front surface of the camera body 2, a grip 4 is provided at the left end and a built-in flash 5 is provided at the upper right. The digital camera 1 employs a pre-flash method that performs pre-flash prior to shooting and sets the amount of light emitted from the built-in flash 5 during shooting.

  As shown in FIG. 2, a shutter button 11 is provided on the upper surface of the grip portion 4. The shutter button 11 is a two-stage switch that can detect a half-pressed state (S1 state) and a fully-pressed state (S2 state) as used in a silver halide camera.

  On the right side of the upper surface of the camera body 2, there is provided a dial-type main switch 15 for switching the power on / off and switching the operation mode among “shooting mode”, “playback mode” and “communication mode”. ing.

  The “shooting mode” is an operation mode in which a subject is shot, image data (hereinafter also referred to as “image” as appropriate) is acquired and recorded in the memory card 9, and the “playback mode” is an image recorded in the memory card 9. This is an operation mode in which data is read and reproduced and displayed. The “communication mode” is an operation mode for performing communication such as transferring image data to an external computer via a USB terminal 27 provided on the back of the camera body 2.

  A data panel 21 for displaying various setting information of the digital camera 1 is provided on the left side of the main switch 15 so that the setting information of the digital camera 1 can be easily grasped.

  In addition, a function dial 16 and a function button 16a for setting items such as “size”, “compression ratio”, and “white balance” of the acquired image data are provided above the side surface of the digital camera 1. . After setting the item to be set by the function dial 16, the setting contents of the set item can be sequentially changed by rotating the selection dial 12 above the grip portion 4 while pressing the function button 16a.

  As shown in FIG. 3, a liquid crystal display (LCD) 23 for performing live view display of subject image data, playback display of recorded image data, various settings, etc. An electronic viewfinder (EVF) 22 is provided. The display on the LCD 23 and the display on the EVF 22 can be switched by operating the display switching lever 17 on the right side of the EVF 22. The central portion of the display switching lever 17 is an information display switching button 17a, and when image data is displayed on the LCD 23 or the EVF 22, it is possible to switch whether or not the setting information is displayed simultaneously.

  On the right side of the LCD 23, a menu button 18 and a cross key 19 are provided. The cross key 19 includes a quadruple switch including an upper switch 19U, a lower switch 19D, a left switch 19L and a right switch 19R, and a center button 19C. When the menu button 18 is pressed, a setting menu is displayed on the LCD 23, and various settings of the digital camera 1 can be performed by operating the cross key 19 while referring to the setting menu.

  A focus mode button 20 for switching the focus mode (focus control method) is provided below the cross key 19. Autofocus control (hereinafter simply referred to as “autofocus”) that automatically drives the lens group in the photographic lens 3 so that a predetermined focus area in the image data is brought into focus every time the focus mode button 20 is pressed. Alternatively, the focus mode is switched between “AF” and manual focus control (hereinafter also simply referred to as “manual focus” or “MF”) for driving the lens group based on an operation input from the user. It is done.

  When the focus mode is AF, the area FA0 corresponding to the focus area is displayed on the LCD 23 or the EVF 22 in the shooting standby state. The user can focus the desired subject image by performing framing so that the desired subject image is arranged in the area FA0.

  Further, when the focus mode is MF, the driving direction and the driving amount of the lens group are determined by an operation input of a focus ring 33 that is rotatably provided at a connection portion between the photographing lens 3 and the camera body 2.

  A battery chamber 24 is provided below the camera body 2. The battery chamber 24 is opened with a battery chamber release lever 24a and is loaded with four AA batteries. The portable digital camera 1 uses an AA dry battery loaded in the battery chamber 24 as a normal drive source, but is supplied from an external source supplied via a power input terminal 25 provided on the right side of the battery chamber 24. It is also possible to use a DC power supply as a drive source.

  A video output terminal 26 is provided on the right side of the power input terminal 25 so that image data can be transferred and displayed on an external monitor.

  Further, a card slot 29 is provided inside the camera body 2, and a memory card 9 for recording image data and the like can be inserted and attached from the side of the camera body 2. An access lamp 28 for displaying that the memory card 9 is being accessed is disposed near the insertion slot of the card slot 29.

<1-2. Internal structure of digital camera>
FIG. 4 is a diagram showing the main internal configuration of the digital camera 1 as functional blocks.

  The lens driving unit 211 determines a lens group in the photographing lens 3 that determines the focus state of the subject image, a diaphragm in the photographing lens 3 that determines the amount of incident light, and the like based on a signal input from the overall control unit 30. To drive.

  The CCD 201 is an image sensor that includes a light receiving unit, a vertical transfer unit, a horizontal transfer unit, an output unit, and the like. The CCD 201 photoelectrically converts the light image of the subject formed by the photographing lens 3 into a signal charge by the light receiving unit, transfers the signal charge via the vertical transfer unit and the horizontal transfer unit, and sequentially outputs the signal charge from the output unit. . The light receiving portion of the CCD 201 is composed of horizontal 2560 × vertical 1920 pixels to which R (red), G (green), and B (blue) color filters are attached, and the signal charges output from the CCD 201 are RGB color components. The image signal has

  As an image signal output mode, the CCD 201 outputs a frame mode that outputs image data of all pixels, and a draft mode that outputs simple image data having pixels of 2560 × 240 by thinning out vertical pixels to 1/8. have. In the shooting standby state, it is set to the draft mode for speeding up, and the frame mode is set to output the recording image data after the shooting instruction.

  The timing generator 210 transmits a drive control signal to the CCD 201 based on a signal input from the overall control unit 30. For example, the vertical synchronization signal VD for transferring the signal charge accumulated in each pixel of the CCD 201 to the vertical transfer unit, the horizontal synchronization signal HD for sequentially transferring the signal charge from the vertical transfer unit to the horizontal transfer unit, and sweeping out unnecessary charges of each pixel An unnecessary charge sweep signal SUB for performing the output, an output mode change signal for changing the output mode to the draft mode or the frame mode, and the like are transmitted.

  The exposure control of the digital camera 1 is performed by adjusting the charge accumulation time (corresponding to the shutter speed: hereinafter also referred to as “shutter speed”) of the CCD 201 and the aperture value. In this specification, the shutter speed and the aperture value are collectively referred to as “exposure control value”.

  The charge accumulation time (shutter speed) of the CCD 201 is adjusted by the number of pulses of the unnecessary sweep signal SUB transmitted from the timing generator 210. FIG. 5 is a diagram for explaining the charge accumulation time of the CCD 201. The CCD 201 transfers the signal charge to the vertical transfer unit for each pulse of the vertical synchronization signal VD supplied from the timing generator 210 at a predetermined cycle V, so that the signal is received at the light receiving unit at the same time as the pulse generation cycle V of the vertical synchronization signal VD. Charge is accumulated.

On the other hand, when the pulse of the unnecessary charge sweep signal SUB is given, the CCD 201 sweeps out the signal charge accumulated in the light receiving unit as unnecessary charges. For this reason, during the time ES during which the pulse of the unnecessary charge sweep signal SUB is given to the CCD 201, the signal charge is not substantially accumulated in the light receiving unit. Therefore, the charge accumulation time EXP in the light receiving unit is expressed by the following equation:
EXP = V-ES
Will be given. Here, since the time ES is determined by the number of pulses of the unnecessary charge sweep signal SUB given to the CCD 201, the charge accumulation time EXP is adjusted by the number of pulses of the unnecessary charge sweep signal SUB. The longer the charge accumulation time EXP, the more signal charges are accumulated in the light receiving unit, and brighter image data is acquired.

  Note that the pulse generation period of the unnecessary charge sweep signal SUB coincides with the pulse generation period H of the horizontal synchronization signal HD. Therefore, the charge accumulation time EXP is given by a time obtained by subtracting an integer multiple of the pulse generation period H of the horizontal synchronization signal HD from the pulse generation period V of the vertical synchronization signal VD.

  On the other hand, the aperture value is a value corresponding to the aperture diameter of the aperture in the taking lens 3, and is selectively set from a plurality of stages in the present embodiment. In the following description, the aperture value is expressed using an AV value in APEX display. For example, the aperture value when the aperture is set to the open state is set to “3” (F = 2.8: hereinafter referred to as “open value”), and the aperture value when the aperture is set to the first level from the open state. The value is set to “4” (F = 4.0), and the aperture value when the aperture is stopped by two steps from the open state is set to “5” (F = 5.6). That is, when the stop is stopped by n stages from the open state, the stop value is set to “3 + n”. As the stop value increases, the aperture diameter of the stop decreases and the amount of incident light is limited.

  Returning to FIG. 4, the signal processing circuit 202 performs predetermined analog signal processing on the image signal (analog signal) output from the CCD 201. The signal processing circuit 202 includes a CDS (correlated double sampling) circuit and an AGC (auto gain control) circuit therein, and reduces noise of the image signal by the CDS circuit and adjusts the gain of the AGC circuit. To adjust the level of the image signal.

  The A / D converter 203 converts each pixel signal (analog signal) output from the signal processing circuit 202 into, for example, a 12-bit digital signal. The value (pixel value) of each pixel output from the A / D converter 203 is expressed as a color component value of a color composed of RGB color components.

  A WB (white balance) correction circuit 204 corrects a shift in color balance due to the influence of the color of the illumination light source (so-called white balance) with respect to the image data output from the A / D converter 203 so that white is white. Correction). The WB correction circuit 204 converts RGB color component values of image data using a conversion table set for each shooting.

  The γ correction circuit 205 performs γ correction on the image data output from the WB correction circuit 204. Usually, the gradation characteristic of image data is corrected so as to match the γ characteristic of a general display device.

  The color correction conversion circuit 206 performs color correction and color space conversion on the image data output from the γ correction circuit 205. Specifically, each pixel value is adjusted (color adjustment) so as to enhance saturation by using a conversion matrix set for each shooting, and each pixel value composed of RGB color components is converted to YCrCb (luminance component). Color space conversion to value Y and color difference component values Cr, Cb).

  The resolution conversion circuit 207 converts the image data output from the color correction conversion circuit 206 to a predetermined resolution. In the case of recording image data output from the CCD 201 set to the frame mode, the image data is converted into image data having a resolution corresponding to the “size” set by the function dial 16 or the like. In the case of simple image data output from the CCD 201 set in the draft mode, the horizontal pixels are thinned out to 1/8, converted into image data composed of horizontal 320 × vertical 240 pixels, and displayed on the EVF 22 or the LCD 23. A live view image is generated.

  Image data acquired in the shooting standby state is also input from the WB correction circuit 204 to the calculation area extraction circuit 208. Further, this image data is output from the calculation area extraction circuit 208 to the AF evaluation value calculation circuit 221, the main photometry calculation circuit 222, and the AF photometry calculation circuit 223, and is used for exposure control and autofocus. Since the image data used for exposure control and autofocus is preferably in a state in which the linear characteristics of the output signal of the CCD 201 are maintained, the image data before being subjected to γ correction is input to the calculation area extraction circuit 208.

  The calculation area extraction circuit 208 extracts the areas to be calculated by the AF evaluation value calculation circuit 221, the main photometry calculation circuit 222, and the AF photometry calculation circuit 223 from the input image data, and extracts the extracted image data. Output to each. The AF evaluation value calculation circuit 221 calculates a focus evaluation value indicating the degree of focusing during autofocus, and the main photometry calculation circuit 222 calculates main exposure for obtaining an exposure control value when acquiring image data for recording. The value BV1 is calculated, and the AF photometric calculation circuit 223 calculates the AF photometric value BV2 for obtaining the exposure control value during autofocus.

  FIG. 6 is a diagram for explaining a region in the image data to be calculated by the main photometry calculation circuit 222. As described above, the CCD 201 acquires image data 71a having horizontal 2560 × vertical 1920 pixels. However, from the CCD 201 set in the draft mode, the vertical pixels are thinned to 1/8 × 2560 × vertical 240. The simplified image data 71b having the pixels is output. The simplified image data 71b is further thinned by 1/8 by the computation area extraction circuit 208, and image data 71c having 320 × 240 pixels that are subject to computation by the main photometry computation circuit 222 is generated. Is done. Since this image data 71c is obtained by uniformly thinning out the vertical and horizontal sides of the image data 71a of all the pixels to 1/8, the area to be calculated by the main photometry calculation circuit 222 corresponds to the entire area of the image data 71a. To do.

  The main photometry calculation circuit 222 divides the image data 71c into, for example, 5 × 5 blocks, and weights coefficients (K1, K2, K3: K1> K2> K3 in this embodiment) for each of the divided blocks. ) Is set. Specifically, as shown in FIG. 6, the central block BL of the image data 71c where the main subject image is likely to exist is set as the exposure attention area, and the maximum weighting coefficient K1 is set in the exposure attention area BL. Further, the weighting coefficient K2 is set for the peripheral blocks of the exposure attention area BL, and the minimum weighting coefficient K3 is set for the other blocks.

Then, the blocks with the same weighting factor set as the same group, the average value of the luminance value of the pixel is calculated for each group, and the weighted average is calculated using the calculated average luminance value and the set weighting factor. And the calculation result is set as the main photometric value BV1. For example, assuming that the average value of the luminance value of the exposure attention area BL is D1, the average value of the luminance values of the peripheral blocks of the exposure attention area BL is D2, and the average value of the luminance values of the other blocks is D3. BV1 is
BV1 = (K1 · D1 + K2 · D2 + K3 · D3) / (K1 + K2 + K3)
Is required.

  On the other hand, the AF evaluation value calculation circuit 221 sets a focus area, which is a focus target area in the image data, as a calculation target area. FIG. 7 is a diagram for explaining a region in image data to be calculated by the AF evaluation value calculation circuit 221.

  As shown in the figure, in the image data 71a acquired by the CCD 201, the focus area FA1 is assigned to the central portion of the image data 71a where the main subject image is likely to exist. The simplified image data 71b is output from the CCD 201 set in the draft mode, and the calculation area extraction circuit 208 extracts an area FA2 of 640 × 80 pixels corresponding to the focus area in the simplified image data 71b. . Then, image data 71 d of only the extracted area FA 2 is generated and input to the AF evaluation value calculation circuit 221. The image data 71d is data that is not thinned out with respect to pixels adjacent in the horizontal direction.

  The AF evaluation value calculation circuit 221 calculates a difference value (contrast) of luminance values of pixels adjacent in the horizontal direction in the input image data 71d as an absolute value, and further calculates a total sum of the calculated difference values in the entire image data. Obtained as the focus evaluation value.

  The AF photometry calculation circuit 223 uses the same area as the AF evaluation value calculation circuit 221 as the calculation target area. For this reason, the AF photometry calculation circuit 223 is also input with the image data 71d of only the area FA2 corresponding to the focus area in the simple image data 71b. The AF photometry calculation circuit 223 calculates the average value of the luminance values of the pixels of the image data 71d, and sets the calculation result as the AF photometry value BV2.

  That is, the main photometry calculation circuit 222 obtains the main photometry value BV1 from the entire area of the image data, and the AF photometry calculation circuit 223 determines from the focus area (more precisely, the area corresponding to the focus area) in the image data. The AF photometric value BV2 is obtained.

  Returning to FIG. 4, the image memory 215 is a memory for storing image data acquired by the CCD 201, and has a storage capacity capable of storing at least one frame of image data output from the CCD 201 set in the frame mode. Yes. Image data acquired by the CCD 201 is subjected to predetermined processing by the signal processing circuit 202 to the resolution conversion unit 207 and then temporarily stored in the image memory 215. The image memory 215 also functions as a buffer memory that stores image data to be displayed on the EVF 22 and the LCD 23.

  The EVF / LCD switching unit 216 switches the output destination of the image data stored in the image memory 215 based on the setting of the display switching lever 17. Thereby, display switching between the EVF 22 and the LCD 23 is performed. In the shooting standby state, simple image data acquired by the CCD 201 every predetermined time is subjected to predetermined processing to be a live view image, and then displayed on the EVF 22 or the LCD 23 via the EVF / LCD switching unit 216. (Live view display). Hereinafter, the EVF 22 and the LCD 23 are collectively referred to as a “display unit” 220.

  Further, the EVF / LCD switching unit 216 also outputs image data to the external monitor I / F 217. The image data output to the external monitor I / F 217 is converted into, for example, an NTSC image signal by the external monitor I / F 217 and sent to the external monitor 62 or the like via the video output terminal 26.

  The compression / decompression unit 213 performs compression processing such as JPEG on the recording image data, and decompresses image data that has been compressed and recorded in the memory card 9. The image data for recording is compressed by the compression / expansion unit 213 at the “compression rate” set by the function dial 16 or the like, and recorded on the memory card 9. Recording and reading of image data to and from the memory card 9 are performed via a card I / F 214 provided in the card slot 29.

  The USB I / F 212 is a communication interface conforming to the USB standard for performing communication with the external computer 61 in the communication mode. Data communication between the USB I / F 212 and the computer 61 is performed via the USB terminal 27.

  The operation unit 10 shows operation members including the shutter button 11, the cross key 19, the focus mode button 20, the focus ring 33, and the like described above as one functional block. The operation input information of the operation unit 10 is input to the overall control unit 30 as a signal. The timer 219 is a clock circuit that manages time such as shooting date and time, and is driven by another power source (not shown).

  The overall control unit 30 is composed of a microcomputer, and comprehensively controls the operation of each member described above of the digital camera 1. The overall control unit 30 includes a CPU 31 that performs various calculation processes, a RAM 32 that is a work area for performing calculations, and a ROM 33 that stores control programs and the like.

  The overall control unit 30 realizes various functions in software. That is, various functions are realized by the CPU 31 performing arithmetic operations according to the control program stored in the ROM 33. Note that a new control program is stored (installed) in the ROM 33 by reading from a memory card (which stores a control program) 9 as a recording medium or transferred from the computer 61 communicating via the USB I / F 212. It is also possible.

  In FIG. 4, the exposure control unit 310 and the focus control unit 320 represent functions realized by the CPU 31 performing arithmetic operations according to a control program stored in the ROM 33 as functional blocks.

  The exposure control unit 310 performs exposure control, and the main exposure calculation unit 311, the AF exposure calculation unit 312 and the exposure signal transmission unit 313 illustrated in FIG.

  The main exposure calculation unit 311 acquires an exposure control value (hereinafter referred to as “recording exposure control value”) when acquiring image data for recording based on the main photometry value BV1 input from the main photometry calculation circuit 222. And an exposure control value (hereinafter referred to as “LV exposure control value”) for obtaining the simple image data for live view.

  The AF exposure calculation unit 312 acquires simple image data for the purpose of acquiring a focus evaluation value based on the AF photometry value BV2 input from the AF photometry calculation circuit 223 (that is, during autofocus). An exposure control value (hereinafter referred to as “AF exposure control value”) is derived.

  The exposure signal transmission unit 313 adjusts the aperture diameter of the diaphragm with respect to the lens driving unit 211 based on one of the derived recording exposure control value, LV exposure control value, and AF exposure control value. And a signal for adjusting the shutter speed are transmitted to the timing generator 210, respectively. The exposure control value to be used is selected according to the operating state of the digital camera 1. Accordingly, the aperture diameter of the diaphragm and the shutter speed are adjusted by the exposure control unit 310 based on the selected exposure control value.

  The focus control unit 320 performs focus control for driving the lens group in the photographic lens 3. In FIG. 4, the AF control unit 321 and the MF control unit 322 indicate functions of the focus control unit 320, respectively. .

  The AF control unit 321 performs autofocus control, and drives the lens group based on the focus evaluation value input from the AF evaluation value calculation circuit 221. Specifically, while transmitting a signal for driving the lens group to the lens driving unit 211, the focus evaluation value obtained from the sequentially acquired simple image data is monitored, and the lens group having the highest focus evaluation value is monitored. The position is the in-focus position.

  On the other hand, the MF control unit 322 performs manual focus control, receives the rotation direction and rotation angle of the focus ring 33 operated by the user, converts them into the driving direction and driving amount of the lens group, respectively, and A signal for driving the group is transmitted to the lens driving unit 211.

<1-3. Shooting mode operation>
Next, the operation of the digital camera 1 will be described. FIG. 8 is a diagram showing a flow of operation of the digital camera 1. In this description, it is assumed that the focus mode is set to AF and the focus mode is not switched.

  When the digital camera 1 is set to the shooting mode, the digital camera 1 enters a shooting standby state, acquires simple image data by the CCD 201 every predetermined time, generates a live view image, and performs a live view operation for displaying on the display unit 220.

  First, the CCD 201 is set to a draft mode for outputting simple image data (step ST1). Then, exposure control for acquiring simple image data for live view is performed based on the LV exposure control value. That is, a signal is transmitted from the exposure signal transmission unit 313 to the lens driving unit 211 and the timing generator 210 so that the actual aperture value and shutter speed become the LV exposure control value (step ST2). When the digital camera 1 is activated, the LV exposure control value is not derived, and therefore an appropriate initial value is used as the exposure control value.

  Subsequently, the simplified image data is acquired in the CCD 201 (step ST3), and the acquired simplified image data is subjected to predetermined processing in the signal processing circuit 202 to the resolution conversion unit 207 to be a live view image, and then displayed. It is displayed on the part 220 (step ST5).

  On the other hand, the simple image data is input to the main photometry calculation circuit 222 and the AF photometry calculation circuit 223 after a predetermined area is extracted by the calculation area extraction circuit 208. The main photometry value calculation circuit 222 calculates the main photometry value BV1, and the AF photometry value calculation circuit 223 calculates the AF photometry value BV2.

  Further, the calculated main photometric value BV1 and AF photometric value BV2 are input to the main exposure calculation unit 311 and the AF exposure calculation unit 312 of the overall control unit 30, respectively. The main exposure calculation unit 311 refers to a predetermined program diagram based on the inputted main photometric value BV1, and derives an exposure control value for LV and an exposure control value for recording. On the other hand, the AF exposure calculation unit 312 refers to a predetermined program diagram based on the input AF photometric value BV2, and derives an AF exposure control value (step ST4).

  The LV exposure control value, the recording exposure control value, and the AF exposure control value derived in this way are each stored in the RAM 32 and can be always selectively extracted.

  The operations in steps ST2 to ST5 (live view operation) are repeated until the shutter button 11 is half-pressed (during No in step ST6). For this reason, the exposure control value for LV, the exposure control value for recording, and the exposure control value for AF are updated to appropriate values according to the subject and held in the RAM 32. Among these, the exposure control value for LV is immediately reflected in exposure control when acquiring simple image data for live view.

  In such a shooting standby state, when the shutter button 11 is half-pressed (Yes in step ST6), the operation shifts to an autofocus operation. Prior to this, the AF exposure control value held in the RAM 32 is set. Based on this, exposure control for acquiring simple image data for the purpose of acquiring the focus evaluation value is performed. That is, a signal is transmitted from the exposure signal transmission unit 313 to the lens driving unit 211 and the timing generator 210 so that the actual aperture value and shutter speed become the AF exposure control value (step ST7). Thereafter, autofocus is performed by the AF control unit 321 (step ST8).

  Since the AF exposure control value is obtained from the area corresponding to the focus area in the simple image data, at least the area corresponding to the focus area in the simple image data acquired during autofocus is appropriate exposure. Accordingly, in a region corresponding to the focus area, lack of contrast due to pixel saturation or blackout does not occur, and an appropriate focus evaluation value is acquired. Thereby, in the digital camera 1, autofocusing is performed quickly and with high accuracy.

  When the shutter button 11 is fully pressed after the autofocus is completed (Yes in step ST9), the process proceeds to an operation for acquiring image data for recording. That is, the CCD 201 is set to the frame mode (step ST10), exposure control based on the exposure control value for recording held in the RAM 32 is performed (step ST11), and image data for recording is acquired by the CCD 201 (step ST11). Step ST12). The acquired image data for recording is subjected to predetermined processing by the signal processing circuit 202 to the resolution conversion unit 207, stored in the image memory 215, compressed by the compression / expansion unit 213, and recorded on the memory card 9. (Step ST13). Thereafter, the process returns to step ST1 again and shifts to a shooting standby state.

  If the operation of the shutter button 11 is released after the autofocus is completed (No in step ST9), the process returns to step ST2 and shifts to the live view operation.

  As described above, the first embodiment has been described. In the digital camera 1 according to the present embodiment, the exposure control is performed based on the AF exposure control value obtained from the focus area during autofocus. Image data in which the focus area is properly exposed can be obtained. Therefore, an appropriate focus evaluation value can be acquired from the focus area in the image data, and autofocus can be performed quickly and with high accuracy.

  In addition, since all of the exposure control value for LV, the exposure control value for recording, and the exposure control value for AF are always held in the RAM 32, when shifting from the live view operation to the autofocus operation, the recording operation from the autofocus operation is performed. It is not necessary to acquire the image data again to obtain the exposure control value when moving to the operation to acquire the image data or when moving from the autofocus operation to the live view operation. Can be migrated.

  Further, the exposure control unit 310 selects an exposure control value used for exposure control from the LV exposure control value, the recording exposure control value, and the AF exposure control value according to the operation state of the digital camera 1. Image data in an exposure state suitable for the operation state of the digital camera 1 can be acquired.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described. The configuration of the digital camera 1 according to the present embodiment is the same as that shown in FIGS. 1 to 3, and the internal configuration is the same as that shown in FIG. The operation of the shooting mode of the digital camera 1 of the present embodiment is almost the same as that of the first embodiment, but the method for deriving the exposure control value is different.

  In general, when focus control is performed, the target main subject is more easily focused as the depth of field is reduced (the distance range of the subject in focus is narrowed). Therefore, in order to improve the accuracy of autofocus, it is preferable to set the aperture value at the time of autofocus to an open value (“3” in the present embodiment) at which the depth of field becomes shallow.

  Also, when moving from live view operation to autofocus operation, if the drive of the aperture occurs, the autofocus operation is delayed, so the aperture value during live view operation matches the aperture value during autofocus. It is preferable. That is, it is preferable to set the aperture value to the open value even during the live view operation.

  On the other hand, when the luminance (brightness) of the subject is relatively high and strong light exceeding the allowable range of the CCD 201 is incident on the CCD 201, the light receiving portion of the CCD 201 is exposed even during signal charge transfer, and the image A band called smear may occur in the data. In order to prevent such smearing, it is necessary to increase the aperture value and suppress the amount of incident light.

  If the aperture value is fixed to the open value during the live view operation, the exposure control is adjusted only by the shutter speed. As described above, the shutter speed is given by a time obtained by subtracting an integral multiple of the pulse generation period H of the horizontal synchronization signal HD from the pulse generation period V of the vertical synchronization signal VD. That is, since the minimum unit time during which the shutter speed can be adjusted depends on the pulse generation period H of the horizontal synchronization signal HD, the exposure amount can be finely adjusted only with the shutter speed, particularly when the luminance of the subject is relatively high. I can't. Therefore, if the aperture value is fixed to an open value or the like during live view when the luminance of the subject is relatively high, the obtained simple image data is not properly exposed, and main metering obtained from this simple image data The accuracy of the value BV1 and the like is lowered.

  In the digital camera 1 of the present embodiment, each exposure control value is set in consideration of the above phenomenon. Hereinafter, with reference to FIG. 9 to FIG. 11, the flow of operations in the shooting mode of the digital camera 1 of the present embodiment will be specifically described.

  In the digital camera 1, operation contents including an exposure control value setting method and the like differ depending on the focus mode. Therefore, first, when the CCD 201 is set to the draft mode (step ST21), it is subsequently determined whether the focus mode is AF or MF (step ST22). When the focus mode is auto focus, the operation after step ST23 is performed. When the focus mode is manual focus, the operation after step ST41 in FIG. 10 is performed.

<2-1. Focus mode: Auto focus>
If the focus mode is autofocus, then, similarly to the first embodiment, exposure control for acquiring live view simple image data is performed based on the LV exposure control value (step ST23). ), Simple image data is acquired in the CCD 201 (step ST24), and the acquired simple image data is subjected to predetermined processing in the signal processing circuit 202 to the resolution conversion unit 207 to be a live view image, and then the display unit. 220 (step ST26).

  On the other hand, the main photometric value BV1 and the AF photometric value BV2 are obtained based on the acquired simple image data, and the exposure control unit 310 further determines the LV exposure control value, the recording exposure control value, and the AF exposure. A control value is derived (step ST25). FIG. 12 is a diagram showing a flow of processing (step ST25) for deriving these exposure control values.

  First, the LV exposure control value is derived by the main exposure calculation unit 311. Prior to this, it is determined whether or not smear may occur in the image data acquired during the live view operation. Specifically, it is determined whether or not the main photometric value BV1 is higher than a predetermined first reference value (in this embodiment, “7” converted to APEX value) (step ST101).

  If smear may occur (Yes in step ST101), the aperture value of the LV exposure control value is set to a value “4” that is narrowed by one step from the open value “3” in order to prevent the occurrence of smear. Further, the shutter speed of the LV exposure control value is derived in accordance with the aperture value “4” (step ST102).

  On the other hand, when there is no possibility of smearing (No in step ST101), the aperture value of the LV exposure control value is set to the open value “3”, and further, the LV exposure is adjusted according to this aperture value “3”. The shutter speed of the control value is derived (step ST103).

  When the LV exposure control value is derived, the main exposure calculation unit 311 subsequently derives the recording exposure control value. Prior to this, it is determined whether or not the accuracy of the main photometric value BV1 has decreased. Is done. Specifically, it is determined whether or not the main photometric value BV1 is higher than a predetermined second reference value (in this embodiment, “10” converted to APEX value) (step ST104).

  If it is determined that the accuracy of the main photometric value BV1 is lowered (Yes in step ST104), an appropriate value can be obtained even if the exposure control value for recording is derived based on the main photometric value BV1. Can not. For this reason, an internal flag (hereinafter referred to as “re-photometry flag”) indicating that it is necessary to obtain the simplified image data again (re-photometry) and derive the exposure control value for recording is turned ON. (Step ST105).

  Then, the main exposure calculation unit 311 derives an exposure control value (hereinafter referred to as “re-photometric exposure control value”) when performing re-photometry. Specifically, the aperture value of the re-photometric exposure control value is set to “5”, and the shutter speed of the re-photometric exposure control value is derived in accordance with the aperture value “5” (step ST106).

  On the other hand, if it is determined that the accuracy of the main photometric value BV1 has not decreased (No in step ST104), an appropriate recording exposure control value can be derived based on the main photometric value BV1. The re-photometry flag is turned off (step ST107). Then, a predetermined program diagram is referred to based on the main photometric value BV1, and a recording exposure control value is derived (step ST108).

  Next, the AF exposure calculation unit 312 derives the AF exposure control value. Prior to this, it is determined whether or not there is a possibility of smearing in the simple image data acquired during autofocus. The Specifically, it is determined whether or not the AF photometric value BV2 is higher than a predetermined first reference value (APEX value converted "7") (step ST109).

  If smear occurs in the simple image data, an appropriate focus evaluation value cannot be obtained. If smear may occur (Yes in step ST109), the aperture value of the AF exposure control value is the open value. A value “4” that is narrowed by one step from “3” is set, and the shutter speed of the AF exposure control value that matches this aperture value “4” is derived (step ST110).

  On the other hand, when there is no possibility of smearing (No in step ST109), it is preferable to reduce the depth of field, so the aperture value is set to the open value “3” in the AF exposure control value. Further, the shutter speed of the AF exposure control value matched with the aperture value “3” is derived (step ST111).

  The LV exposure control value, the recording exposure control value (or the re-photometric exposure control value) and the AF exposure control value derived in this way are respectively stored in the RAM 32 and can be always selectively extracted. The

  Returning to FIG. 9, the live view operation in steps ST23 to ST26 described above is repeated until the shutter button 11 is half-pressed (during No in step ST27). Therefore, as in the first embodiment, the LV exposure control value, the recording exposure control value (or the re-photometric exposure control value), and the AF exposure control value are updated to appropriate values according to the subject. While being held in the RAM 32. The exposure control value for LV whose aperture value is set to “3” or “4” is immediately reflected in the exposure control when acquiring the simple image data for live view. Also, the re-photometry flag is switched ON / OFF according to the subject.

  If the focus mode button 20 is operated in the shooting standby state (Yes in step ST31), the focus mode is switched to manual focus (step ST32). Then, the process returns to step ST22, and thereafter, the operation when the focus mode is MF (FIG. 10: after step ST41) is performed.

  In such a shooting standby state, when the shutter button 11 is half-pressed (Yes in step ST27), the objective is to obtain a focus evaluation value based on the AF exposure control value, as in the first embodiment. Exposure control for acquiring the simplified image data is performed (step ST28), and autofocus is performed by the AF control unit 321 (step ST29).

  At this time, the aperture value of the AF exposure control value is “3” or “4”, and on the other hand, the aperture value of the LV exposure control value is also “3” or “4”. Even if the diaphragm is driven, only one stage is driven. For this reason, when shifting from the live view operation to the autofocus operation, the operation can be smoothly shifted, and as a result, the time until the end of the autofocus can be shortened.

  When the operation of the shutter button 11 is released after the autofocus is finished (No in step ST30), the process returns to step ST22 and again shifts to the live view operation. The operation can be shifted to.

  When the shutter button 11 is fully pressed after completion of autofocus (Yes in step ST30), the process proceeds to an operation of acquiring image data for recording (FIG. 11: after step ST51).

  First, it is determined whether or not the re-photometry flag is ON (step ST51). If the re-photometry flag is ON, exposure control is performed based on the re-photometry exposure control value (step ST52), and simple image data for re-photometry is acquired (step ST53). The main photometric value BV1 is acquired based on the simple image, and the recording exposure control value is derived based on the main photometric value BV1 (step ST54).

  At this time, since the aperture value of the re-photometric exposure control value is “5”, the aperture value is larger than the aperture value “3” or “4” at the time of auto focus and live view in consideration thereof, and the aperture is narrowed down. . That is, when the main photometric value BV1 corresponding to the brightness of the subject is higher than the second reference value, the aperture value is set to a value larger than the value at the time of autofocus. Therefore, since the main photometric value BV1 with high accuracy is obtained by suppressing the amount of incident light, an appropriate recording exposure control value can be derived.

  When the exposure control value for recording is derived, the CCD 201 is set to the frame mode (step ST55), exposure control based on the exposure control value for recording is performed (step ST56), and image data for recording is acquired by the CCD 201. Then, the image data on which the predetermined processing has been performed is recorded on the memory card 9 (step ST58). After that, the process returns to step ST1 and shifts to the shooting standby state.

  When the re-photometry flag is OFF (No in step ST51), since the recording exposure control value has been derived, the operations in steps ST52 to ST54 are not performed, and the operations in steps ST55 to ST58 are performed as they are. The Rukoto.

<2-2. Focus mode: During manual focus>
Next, the operation when the focus mode is manual focus (FIG. 10) will be described. First, exposure control for acquiring simple image data for live view is performed based on the LV exposure control value (step ST41), simple image data is acquired in the CCD 201 (step ST42), and the acquired simple image data is acquired. A live view image is generated and displayed on the display unit 220 (step ST44).

  On the other hand, the exposure control value is obtained based on the acquired simple image data. However, when the focus mode is MF, it is not necessary to derive the AF exposure control value. Therefore, only the main photometry value BV1 is obtained by the main photometry calculation circuit 222 based on the simple image data, and only the exposure control value for LV and the exposure control value for recording are derived by the main exposure calculation unit 311 of the exposure control unit 310. (Step ST43).

  As described above, when the focus mode is AF, the aperture value of the exposure control value for LV is set to the open side value (“3” or “4”) in consideration of the shift to the autofocus operation. However, when the focus mode is MF, the aperture value is not necessarily set to the open side value.

  Therefore, when the main photometric value BV1 corresponding to the brightness of the subject is higher than the predetermined second reference value, the LV exposure is performed so that the main photometric value BV1 with high accuracy can be acquired during the live view operation. Set the aperture value of the control value. Specifically, it is set to a value (“5” or more) larger than the aperture value of the LV exposure control value when the focus mode is AF. As a result, since the recording exposure control value can be always derived during the live view operation, it is not necessary to perform re-photometry when acquiring the recording image data.

  The live view operation in steps ST41 to ST44 is repeated until the shutter button 11 is half-pressed (during No in step ST47). When the focus ring 33 is operated during the live view operation (step ST45), the lens group is driven by the MF control unit 322 (step ST46).

  When the focus mode button 20 is operated in the shooting standby state (Yes in step ST48), the focus mode is switched to autofocus (step ST49). Then, the process returns to step ST22, and thereafter, the operation when the focus mode is AF (FIG. 9: after step ST23) is performed.

  In such a shooting standby state, when the shutter button 11 is half-pressed (Yes in step ST47), since the focus mode is MF, autofocus is not performed, and whether or not the shutter button 11 is fully pressed is determined. Determination is made (step ST50). When the operation of the shutter button 11 is released, the process shifts to the live view operation again. On the other hand, when the shutter button 11 is fully pressed, an operation for acquiring image data for recording (FIG. 11: Step). The process proceeds to ST51 and later. The operation for acquiring the recording image data is as described above, but since the recording exposure control value has been derived, re-photometry (steps ST52 to ST54) is not performed.

  Although the second embodiment has been described above, in the digital camera 1 of the present embodiment, the aperture value for the live view operation or the like is different depending on whether the focus mode is AF or MF. Since the setting methods are different, an optimum aperture value can be set for each of AF and MF.

  That is, when the focus mode is AF, the aperture value at the time of live view operation and autofocus is set to the open side value, so that it is possible to quickly shift from the live view operation to the autofocus operation and Accuracy can be improved. In addition, when the brightness of the subject is relatively high, the aperture value is set to a relatively large value after the autofocus, and the photometry is performed again. Therefore, the accuracy of the main photometric value BV1 for determining the recording exposure control value Can be improved.

  On the other hand, when the focus mode is MF, the accuracy of the main photometric value BV1 for determining the recording exposure control value can be improved by setting the aperture value during the live view operation to a relatively large value. As a result, it is not necessary to perform re-photometry, and it is possible to quickly shift from a live view operation to an operation for acquiring recording image data.

<3. Third Embodiment>
Next, a third embodiment of the present invention will be described. The configuration of the digital camera 1 according to the present embodiment is the same as that shown in FIGS. 1 to 3, and the internal configuration is the same as that shown in FIG. Further, the operation of the shooting mode of the digital camera 1 of the present embodiment is almost the same as that shown in FIGS. 9 to 11, but the processing of step ST43 in FIG. 10 is different.

  FIG. 13 is a diagram showing the flow of the process of step ST43 of the digital camera 1 of the present embodiment, that is, the process of deriving the exposure control value when the focus mode is MF.

  In the present embodiment, first, the aperture value of LV exposure control is set to the open value “3”, and the shutter speed of the LV exposure control value is derived in accordance with this aperture value “3” (step ST121). ). That is, in the digital camera 1 of the present embodiment, the aperture value of the LV exposure control value is fixed to the open value (“3” in the present embodiment).

  If the aperture value of the LV exposure control value is fixed to the open value, the accuracy of the main photometric value BV1 acquired during the live view operation may be reduced. Therefore, when the LV exposure control value is derived, the operations of steps ST122 to ST126 are performed in the same manner as steps ST104 to ST108 in FIG. 12, and the exposure control value for recording or the re-photometric exposure is performed by the main exposure calculation unit 311. A control value is derived.

  When performing manual focus (FIG. 10: Steps ST45 and ST46), the user operates the focus ring 33 while referring to the live view image displayed on the display unit 220, and a desired subject image in the live view image. Is brought into focus. At this time, as in the present embodiment, the aperture value is fixed to the open value and the depth of field is reduced, so that the in-focus position in the live view image is limited. It becomes easy to focus on the image.

  In the second embodiment, when the focus mode is MF, re-photometry is not performed during the operation of acquiring the recording image data. However, in this embodiment, the re-photometry flag is ON. If it becomes, re-photometry is performed.

<4. Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. The digital camera 1 according to the present embodiment has a function of allowing a user to specify a focusing target area in image data, that is, a focus area.

  FIG. 14 is a diagram illustrating a main configuration of the digital camera 1 according to the present embodiment, and corresponds to a rear view of the digital camera 1. Other configurations of the digital camera 1 are the same as those shown in FIGS. 1 and 2, and the internal configuration is the same as that shown in FIG.

  In the digital camera 1 of the present embodiment, when the focus mode is set to AF, the cursor CR indicating the center position of the focus area is displayed on the display unit 220 in the shooting standby state. The cursor CR can be moved to an arbitrary position by an operation input of the cross key 19, and the user moves the cursor CR to a desired position in the live view image displayed on the display unit 220 to focus. Specify the subject image to be used.

  In the digital camera 1 of the present embodiment, the focus mode is switched from MF to AF by pressing the focus mode button 20 as in the above embodiment, but from the focus mode AF to MF. Is switched by operating the focus ring 33.

  FIG. 15 is a diagram for explaining regions to be calculated by the AF evaluation value calculation circuit 221, the main photometry calculation circuit 222, and the AF photometry calculation circuit 223 of the present embodiment.

  As shown in the figure, in the image data 71a acquired by the CCD 201, a position corresponding to the cursor CR position on the screen of the display unit 220 is a focus point FFP, and an area of a predetermined size centered on the focus point FFP. Is the focus area FFA.

  When the digital camera 1 is activated, the focus point FFP and the focus area FFA are arranged at the reference positions (positions indicated by the symbols FFP0 and FFA0 in FIG. 15) in the center of the image data. When the cursor CR is moved on the screen of the display unit 220, the focus point FFP and the focus area FFA are also moved along with the movement of the cursor CR. For example, FIG. 15 shows a state in which the focus point FFP and the focus area FFA are moved from the reference positions FFP0 and FFA0 to the positions indicated by the symbols FFP1 and FFA1, respectively.

  The calculation area extraction circuit 208 of the present embodiment extracts an area FFA3 of 640 × 80 pixels corresponding to the designated focus area from the simple image data 71b output from the CCD 201. Then, the image data 71d of only the area FFA3 is output to the AF evaluation value calculation circuit 221 and the AF photometry calculation circuit 223, respectively.

  As a result, the focus evaluation value is obtained from the area corresponding to the designated focus area, and the lens group is driven based on the focus evaluation value, so that the designated focus area in the image data is in focus. It becomes. Further, since the AF photometric value BV2 is obtained from the area corresponding to the designated focus area, and the AF exposure control value is obtained based on the AF photometric value BV2, an appropriate focus can be obtained during autofocus. An evaluation value can be acquired.

  Further, the calculation area extraction circuit 208 generates image data 71c of horizontal 320 × vertical 240 pixels to be calculated by the main photometry calculation circuit 222 from the simple image data 71b, and outputs the image data 71c to the main photometry calculation circuit 222.

  The main photometry calculation circuit 222 divides the image data 71c into 5 × 5 blocks in the same manner as in the above embodiment, and the weighting coefficients (K1, K2, K3: K1> K2) for each of the divided blocks. > K3) is set. At this time, the position where the focus point FFP is present in the image data 71a corresponds to the position where the main subject image exists. For this reason, a block including the position corresponding to the focus point FFP (block BL1 in FIG. 15) is selected as the exposure attention area for setting the maximum weighting coefficient K1 among the divided blocks. That is, an area corresponding to the focus area in the image data 71c is set as an exposure attention area.

  When the exposure attention area is selected, the main photometry calculation circuit 222 sets the maximum weighting coefficient K1 for the exposure attention area and sets the weighting coefficient K2 for the peripheral blocks of the exposure attention area, as in the above embodiment. Furthermore, the minimum weighting coefficient K3 is set for the other blocks. Then, the blocks with the same weighting factor set as the same group, the average value of the luminance value of the pixel is calculated for each group, and the weighted average is calculated using the calculated average luminance value and the set weighting factor. The calculation result is set as the main photometric value.

  If the focus area FFA is at the reference position FFA0, the central block BL0 in the image data 71c is selected as the exposure attention area. For this reason, the position of the central block BL0 is set as the reference position of the exposure attention area.

  Next, the operation of the digital camera 1 of the present embodiment will be described. FIG. 16 and FIG. 17 are diagrams showing an operation flow in the photographing mode of the digital camera 1 of the present embodiment.

  First, the CCD 201 is set to the draft mode (step ST61), and then it is determined whether the focus mode is AF or MF (step ST62).

  When the focus mode is AF, exposure control for live view, acquisition of simple image data, derivation of each exposure control value, and display of a live view image are performed in the same manner as in steps ST23 to ST26 of FIG. Step ST63). However, as described above, the exposure attention area when the main photometric value BV1 is obtained is an area corresponding to the focus area, and the area for obtaining the AF photometric value BV2 is an area corresponding to the focus area.

  Such a live view operation is repeated until the shutter button 11 is half-pressed (during No in step ST66). During the live view operation, the operation is performed when the cross key 19 is operated (step ST64). The contents are received by the AF control unit 321 and the cursor CR position on the screen of the display unit 220 is moved. Along with this, the focus point and the focus area are also moved (step ST65). Such movement of the focus area is immediately reflected during the live view operation, and the exposure attention area when the main photometric value BV1 is obtained and the area for obtaining the AF photometric value BV2 are also changed.

  If the shutter button 11 is half-pressed in the shooting standby state (Yes in step ST66), then exposure control is performed based on the AF exposure control value (step ST67), and autofocus is performed (step ST68). ). When the shutter button 11 is fully pressed (step ST69), the recording image data acquisition operation similar to that shown in FIG. 11 is performed thereafter.

  In the shooting standby state when the focus mode is AF as described above, when the focus ring 33 is operated (step ST70), the focus mode is switched to manual focus (step ST71).

  As described above, when the focus mode is switched from AF to MF, the position of the lens group is not accurately determined by autofocus, and the position of the lens group is finely adjusted by manual focus in many cases. For this reason, the framing (the position of the main subject image in the image data) is often not changed, and when the focus area is moved in accordance with the position of the main subject image (that is, the position of the focus area (that is, It is highly possible that the main subject image still exists at the position of the exposure attention area.

  The main photometric value BV1 is preferably acquired from the position of the main subject image. Therefore, when the focus mode is switched from AF to MF in this way, the digital camera 1 of the present embodiment maintains the position of the exposure attention area for obtaining the main photometric value BV1 without returning to the reference position. I have to.

  Subsequently, a value indicating the driving amount of the lens group input to the focus ring 33 after the change of the focus mode to MF (hereinafter referred to as “changed driving amount”) is initialized (step ST72). . Then, the process returns to step ST62, and thereafter, the operation when the focus mode is MF (FIG. 17: after step ST81) is performed.

  When the focus mode is MF, exposure control for live view, acquisition of simple image data, derivation of each exposure control value, and display of a live view image are performed in the same manner as steps ST41 to ST44 in FIG. ST81). However, when the focus mode is switched from AF to MF, the position of the exposure attention area when obtaining the main photometric value BV1 is the position held when the focus mode is switched.

  Such a live view operation is repeated until the shutter button 11 is half pressed (during No in step ST87). When the focus ring 33 is operated during the live view operation (step ST82), The lens group is driven according to the driving amount input by the focus ring 33 (step ST83).

  At this time, if the position of the exposure attention area is held by the change of the focus mode from AF to MF and is not the reference position (Yes in step ST84), it is determined whether or not the changed drive amount has exceeded a predetermined reference amount. Determination is made (step ST85).

  If the post-change drive amount is equal to or less than the predetermined reference amount (No in step ST85), it is assumed that the position of the main subject image has not been changed since this is an operation for fine adjustment of the lens group position. The position of the exposure attention area remains held.

  On the other hand, if the post-change drive amount exceeds a predetermined reference amount, it is assumed that the position of the main subject image has been changed, so the exposure attention area is located at the reference position where the main subject image is likely to exist. The position is returned (step ST86).

  In the shooting standby state, when the shutter button 11 is half-pressed (step ST87), it is determined whether or not the shutter button 11 is fully pressed (step ST88). The recording image data acquisition operation is performed.

  When the focus mode button 20 is operated in the shooting standby state (Yes in step ST89), the focus mode is switched to auto focus (step ST90). Then, the focus area is set as the reference position (step ST91), the process returns to step ST62, and thereafter, the operation when the focus mode is AF (FIG. 16: step ST63 and subsequent steps) is performed.

  Although the fourth embodiment has been described above, in the digital camera 1 of the present embodiment, the position of the exposure attention area is held when the focus mode is switched from AF to MF. Therefore, even when fine adjustment of the lens group is performed, the main photometric value BV1 can be obtained from an appropriate main subject image, and exposure control according to the main subject can be performed.

<5. Fifth embodiment>
Next, a fifth embodiment of the present invention will be described. In the fourth embodiment, the exposure attention area is returned to the reference position when the drive amount input by the focus ring 33 exceeds a predetermined reference amount. However, the digital camera of the present embodiment In 1, the exposure attention area is returned to the reference position when a predetermined time elapses after the focus mode is changed from AF to MF.

  The configuration of the digital camera 1 of the present embodiment is the same as that shown in FIGS. 1, 3 and 14, and the internal configuration is the same as that shown in FIG.

  18 and 19 are diagrams showing the flow of operations in the shooting mode of the digital camera 1 of the present embodiment. Since the operation of the shooting mode of the digital camera 1 according to the present embodiment is almost the same as that shown in FIGS.

  When the focus ring 33 is operated in the shooting standby state when the focus mode is AF (step ST70), the focus mode is switched to manual focus while the position of the exposure attention area is maintained (step ST71). ).

  Subsequently, in order to monitor the elapsed time after the focus mode is switched from AF to MF, the timer 219 starts measuring time (step ST721). Thereafter, the process returns to step ST62, and the operation when the focus mode is MF is performed.

  When the focus mode is MF, whether or not the position of the exposure attention area is moved from the reference position regardless of whether or not the focus ring 33 is operated in the shooting standby state (FIG. 19: step ST821). Is determined (step ST841).

  If the exposure area of interest is not the reference position, it is determined whether or not the elapsed time counted by the timer 219 exceeds a predetermined reference time (step ST851). If the elapsed time exceeds a predetermined reference time, it is assumed that the position of the main subject image has been changed. Therefore, the position of the exposure attention area is at the reference position where the main subject image is likely to exist. It will be returned (step ST86).

<6. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible.

  For example, in the digital camera 1 of the above embodiment, the AF exposure control value is obtained only from the focus area (more precisely, the area corresponding to the focus area), but the brightness of the peripheral area of the focus area is also taken into consideration. You may make it ask for it. In this case, for example, the maximum weighting coefficient is set in the focus area and the weighted average is performed. Even in this case, an appropriate AF exposure control value can be obtained.

  The digital camera 1 according to the above embodiment acquires the exposure control value for recording and the exposure control value for AF in the shooting standby state. This method is used to fix the exposure control value. It is also possible to apply to a digital camera having an AE lock function.

  In a digital camera having an AE lock function, when there is no AE lock instruction, both the recording exposure control value and the AF exposure control value are updated in the same manner as in the above embodiment, and recording is performed after the AE lock instruction. The exposure control value for update is stopped and only the exposure control value for AF is updated. As a result, even when an AE lock instruction is given, an appropriate focus evaluation value can be obtained during autofocus.

  Further, when a digital camera equipped with such an AE lock function sets the flash emission amount in the pre-emission method, the pre-emission is performed at the first shooting after the AE lock instruction, and the flash emission amount is obtained. The obtained light emission amount is stored in an internal RAM or the like. In the second and subsequent shootings, the flash emission amount is set to the calculated emission amount so that pre-emission is not performed. Thereby, it is possible to save power and increase the speed of shooting.

  The specific embodiments described above include inventions having the following configurations.

(1) In the digital camera according to claim 2,
The digital camera according to claim 1, wherein the exposure control means selects an exposure control value used for exposure control from the focus exposure control value and the recording exposure control value according to an operating state of the digital camera.

  According to this, since the exposure control value is selectively used according to the operation state of the digital camera, it is possible to acquire image data in an exposure state suitable for the operation state.

(2) In the digital camera according to claim 4,
The aperture value set by the aperture value setting unit when the focus control unit performs manual focus control is greater than or equal to the aperture value set when the focus control unit performs autofocus control. Digital camera.

  According to this, at the time of autofocus control, by setting the aperture value to a relatively small value, the depth of field becomes shallow and the focusing accuracy is improved. On the other hand, in manual focus control, by setting the aperture value to a relatively large value, the photometric accuracy is improved and the photographing speed is improved.

(3) In the digital camera according to claim 4,
The digital camera according to claim 1, wherein when the focus control means performs manual focus control, the aperture value set by the aperture value setting means is an open value.

  According to this, by setting the aperture value to the open value at the time of manual focus control, the depth of field becomes shallow and focusing becomes easy, and the operability is improved.

(4) A digital camera having imaging means for acquiring image data of a subject via an optical system,
Display means capable of displaying image data acquired by the imaging means in a shooting standby state;
Designation means for accepting designation of the position of the focusing target area on the screen of the display means;
Based on the autofocus control for driving the optical system so that the focus target area in the image data acquired by the imaging means is in focus, and the driving amount input by the driving amount input means. A focus control means capable of switching a focus control method between manual focus control for driving the system;
Exposure calculation means for deriving an exposure control value from the image data, with a predetermined exposure attention area in the image data acquired by the imaging means in the photographing standby state as a maximum specific gravity area;
With
The exposure calculation means includes
When the focus control method of the focus control means is autofocus control, an area corresponding to the focus target area in the image data is set as the exposure attention area, and
The digital camera characterized in that when the focus control means switches the focus control method from autofocus control to manual focus control, the position of the exposure attention area is held.

  According to this, immediately after switching from autofocus control to manual focus control, it is assumed that the main subject exists in the vicinity of the focusing target area designated by the designation means. Therefore, it is possible to derive an exposure control value suitable for the main subject by maintaining the position of the exposure attention area for deriving the exposure control value.

(5) In the digital camera described in (4) above,
The focus control means switches the focus control method from autofocus control to manual focus control when input is performed by the drive amount input means,
The digital camera according to claim 1, wherein the exposure calculation means returns the position of the exposure attention area to a predetermined reference position when the drive amount input by the drive amount input means exceeds a predetermined reference amount.

  According to this, when the drive amount input by the drive amount input means exceeds a predetermined reference amount, it is assumed that the position of the main subject has moved. Therefore, the exposure control value suitable for the main subject can be derived by returning the attention area for deriving the exposure control value to the predetermined reference position.

(6) In the digital camera described in (4) above,
The exposure calculation means sets the position of the exposure attention area to a predetermined position when the elapsed time from the time when the focus control means switches the focus control method from autofocus control to manual focus control exceeds a predetermined reference time. A digital camera characterized by returning to a reference position.

  According to this, when the elapsed time from the time when the auto focus control is switched to the manual focus control exceeds a predetermined reference time, it is assumed that the position of the main subject has moved. Therefore, the exposure control value suitable for the main subject can be derived by returning the attention area for deriving the exposure control value to the predetermined reference position.

It is a front view which shows the principal part structure of the digital camera which concerns on embodiment of this invention. It is a top view which shows the principal part structure of a digital camera. It is a rear view which shows the principal part structure of a digital camera. It is a figure which shows the main internal structures of a digital camera as a functional block. It is a figure for demonstrating the charge accumulation time of CCD. It is a figure for demonstrating the area | region in the image data made into the calculation object by the main photometry calculating circuit. It is a figure for demonstrating the area | region in the image data which AF evaluation value calculating circuit makes calculation object. It is a figure which shows the flow of operation | movement of the imaging | photography mode of the digital camera of 1st Embodiment. It is a figure which shows the flow of operation | movement of the imaging | photography mode of the digital camera of 2nd Embodiment. It is a figure which shows the flow of operation | movement of the imaging | photography mode of the digital camera of 2nd Embodiment. It is a figure which shows the flow of operation | movement of the imaging | photography mode of the digital camera of 2nd Embodiment. It is a figure which shows the flow of the process which derives | leads-out the exposure control value in case the focus mode in AF is 2nd Embodiment. It is a figure which shows the flow of a process which derives | leads-out the exposure control value in case the focus mode is MF in 3rd Embodiment. It is a rear view which shows the principal part structure of the digital camera of 4th Embodiment. It is a figure for demonstrating the area | region made into the calculation object by the main photometry calculating circuit etc. of the digital camera of 4th Embodiment. It is a figure which shows the flow of operation | movement in the imaging | photography mode of the digital camera of 4th Embodiment. It is a figure which shows the flow of operation | movement in the imaging | photography mode of the digital camera of 4th Embodiment. It is a figure which shows the flow of operation | movement in the imaging | photography mode of the digital camera of 5th Embodiment. It is a figure which shows the flow of operation | movement in the imaging | photography mode of the digital camera of 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 2 Camera main-body part 3 Shooting lens 11 Shutter button 19 Cross key 20 Focus mode button 33 Focus ring 310 Exposure control part 320 Focus control part

Claims (5)

A digital camera having imaging means for acquiring image data of a subject via an optical system,
Focus control means for performing autofocus control for driving the optical system so that a predetermined focus target area in the image data acquired by the imaging means is in focus;
A focus exposure calculation means for deriving a focus exposure control value from the image data, with the focus target area in the image data acquired by the imaging means in a shooting standby state as a maximum specific gravity area;
Exposure control means for performing exposure control of the imaging means using the focus exposure control value when the focus control means performs autofocus control;
A digital camera comprising: The digital camera according to claim 1, wherein
A recording exposure calculating means for deriving a recording exposure control value used by the exposure control means when acquiring recording image data from the image data acquired by the imaging means in a shooting standby state;
Storage means for holding both the focus exposure control value and the recording exposure control value;
A digital camera, further comprising: A digital camera having imaging means for acquiring image data of a subject via an optical system,
Focus control means for performing autofocus control of the optical system;
Photometric means for determining the brightness of the subject from image data acquired by the imaging means in a shooting standby state;
An aperture value setting means for setting an aperture value of the optical system based on the brightness of the subject;
With
When the brightness of the subject is higher than a predetermined reference value,
After the focus control means performs autofocus control,
The aperture value setting means sets the aperture value of the optical system to a value larger than the value when performing autofocus control,
A digital camera characterized in that the photometric means obtains the brightness of the subject. A digital camera having imaging means for acquiring image data of a subject via an optical system,
Focus control between autofocus control that drives the optical system so that image data acquired by the imaging means is in focus and manual focus control that drives the optical system based on operation input Focus control means that can switch the method,
Photometric means for determining the brightness of the subject from image data acquired by the imaging means;
An aperture value setting means for setting an aperture value of the optical system based on the brightness of the subject;
With
When the brightness of the subject is higher than a predetermined reference value,
The aperture value setting means sets the aperture value of the optical system differently depending on whether the focus control method of the focus control means is autofocus control or manual focus control. . An exposure control device that performs exposure control of an imaging unit that acquires image data of a subject via an optical system,
In the image data acquired by the imaging unit in the shooting standby state, the focus control unit that performs autofocus control of the optical system is set to a focus area used for focus evaluation as a maximum specific gravity region. A focus exposure calculation means for deriving an exposure control value;
With
An exposure control apparatus characterized in that when the focus control means performs autofocus control, exposure control of the imaging means is performed using the focus exposure control value.

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