JP2006030984A - Image-taking apparatus and focusing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image-taking apparatus which is capable of effectively reducing the influence of the one-side blur by an excellent automatic focusing function. <P>SOLUTION: The image-taking apparatus comprises a focus detector 105, which detects the focus state of a plurality of focus detection areas 11 to 19 provided in an image-taking screen, and a selector 115, which selects a focus target area from a plurality of focus detection areas based on the detection result of the focus detector, an image-taking lens 101 being focused on an object in the focus target area. In a case where a first object distance to a first object is longer than a first predetermined distance and a second object distance to a second object, which exists on an outer side of the first object in the image-taking screen, is shorter than the first object distance by a second predetermined distance or more, the selector selects the focus detection area corresponding to the second object as the focus target area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus capable of controlling focusing on a focus detection area selected from a plurality of focus detection areas.

With the spread of digital cameras in recent years, there has been an increasing demand for improvement in image quality by improving an automatic focus adjustment (AF) function. Conventional AF apparatuses generally employ a contrast detection method that performs focus adjustment with a focus lens position where the high-frequency component of the luminance signal of the subject image formed on the image sensor is maximized as the focus position. In addition, a plurality of focus detection areas are provided in the shooting screen so that focusing is possible even when no subject exists in the center of the shooting screen, and the closest focus detection area in which the in-focus state is obtained is the closest. A camera that performs focus adjustment on a focus detection region corresponding to the subject distance is also known.

  However, the focus detection accuracy deteriorates when an inclination or a center shift of the photographing lens and the image sensor or an inclination of a lens group constituting the photographing lens occurs due to an assembly error or the like. And performing AF based on focus detection information with low accuracy causes so-called blurring. One side of the shooting screen is in focus, but the other side or the center of the screen is not in focus.

To deal with such a problem, for example, Patent Document 1 compares deviation information between subject distances (hereinafter referred to as in-focus distances) at which in-focus states are obtained in a plurality of focus detection areas with reference deviations, and the deviation information. A camera is disclosed that changes focus adjustment control depending on whether or not exceeds a reference deviation. According to this publication, if the focus distances in the focus detection areas are substantially the same, focus adjustment is performed on the focus detection area at the center of the screen in order to reduce the influence of blurring.
Japanese Patent Laid-Open No. 2003-222787 (Japanese Patent Laid-Open No. 2003-222787)

  However, in the camera disclosed in Patent Document 1, it is difficult to obtain a focus on a subject other than the center of the screen, and a large blur occurs because focus adjustment is performed on a subject that is substantially equidistant. There is a problem that it is difficult to obtain the best focus state.

  For example, in the scene as shown in FIG. 7, if the deviation between the in-focus distances corresponding to the persons P1, P2 located on the left and right of the table and the table lamp S over the table T is within a predetermined deviation, the table at the center of the screen The focus will be adjusted to the desk lamp. Although it is almost equidistant, it is not the best focus for people. In addition, when photographing a distant view such as a landscape, the entire photographing screen becomes a long distance and the depth of field becomes deep, so that it can be regarded as a substantially flat subject, and thus is particularly susceptible to blurring.

  An object of the present invention is to provide a photographing apparatus and a focus adjustment method capable of effectively reducing the influence of blurring by an excellent automatic focus adjustment function.

  An imaging apparatus according to one aspect of the present invention includes a focus detection unit that detects a focus state in a plurality of focus detection areas provided in a shooting screen, and a detection result by the focus detection unit among the plurality of focus detection areas. Selection means for selecting a focus target area for focusing the photographic lens based on the above. Then, the selection means has a second subject up to the second subject that has a first subject distance to the first subject that is farther than the first predetermined distance and that is present outside the first subject on the shooting screen. When the subject distance is closer to the second predetermined distance than the first subject distance, the focus detection area corresponding to the second subject is selected as the focusing target area.

  An imaging apparatus according to another aspect of the present invention includes a focus detection unit that detects a focus state in a plurality of image areas provided in a shooting screen, and the focus detection unit among the plurality of image areas. Selection means for selecting a focus target area for focusing the photographing lens based on the detection result. Then, the selection means has a first subject distance to the first subject displayed in the first screen area on the photographing screen that is farther than the first predetermined distance, and on the photographing screen than the first subject. When the second subject distance to the second subject displayed on the outer second screen region is closer than the first subject distance by a second predetermined distance or more, the image region corresponding to the second subject is displayed. Select as the focus target area.

  According to another aspect of the present invention, a focus adjustment method includes a focus detection step for detecting a focus state in a plurality of focus detection areas provided in a shooting screen, and focus detection among the focus detection areas. And a selection step of selecting a focus target area for focusing the photographic lens based on the detection result of the step. Then, in the selection step, the second subject to the second subject that has a first subject distance to the first subject that is farther than the first predetermined distance and that is outside the first subject on the shooting screen. When the subject distance is closer to the second predetermined distance than the first subject distance, the focus detection area corresponding to the second subject is selected as the focusing target area.

  Furthermore, a focus adjustment method according to another aspect of the present invention includes a focus detection step for detecting a focus state in a plurality of image areas provided in a shooting screen, and a focus detection step among the plurality of image areas. And a selection step of selecting a focus target area for focusing the photographic lens based on the detection result. Then, in the selection step, the first subject distance to the first subject displayed in the first screen area on the photographing screen is longer than the first predetermined distance and on the photographing screen than the first subject. When the second subject distance to the second subject displayed on the outer second screen region is closer than the first subject distance by a second predetermined distance or more, the image region corresponding to the second subject is displayed. It selects as a focusing target area | region, It is characterized by the above-mentioned.

  According to the present invention, it is possible to effectively reduce the influence of blurring by an excellent automatic focus adjustment function.

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

  FIG. 1A shows a configuration of an electronic camera 100 that is an embodiment of the present invention. The electronic camera 100 includes a photographing lens 101, an aperture and shutter 102, an automatic exposure (AE) processing unit 103, a focus lens 104, an AF processing unit (driver) 105, a flash 106, a flash processing unit 107, an image sensor (a CCD sensor, 108, A / D converter 109, image processor 110, white balance processor 111, format converter 112, DRAM 113, image processor 114, system controller (focus detector, selector and (Distance calculator) 115, VRAM 116, operation display unit 117, operation unit 118, attitude detection sensor 119, main switch (SW) 120, first stroke switch SW1 and second stroke switch with modes SW 121, 122, and 123, respectively. It has SW2.

  The photographing lens 101 includes a zoom mechanism, and forms a subject image on the image sensor 108. The aperture and shutter 102 controls the amount of light. The automatic exposure (AE) processing unit 103 determines the exposure automatically by determining the brightness of the subject. The focus lens 104 focuses on the image sensor 108. The focus lens 104 shown in FIG. 1 includes a drive unit (stepping motor or the like) (not shown) and a detector (position detector) 104a such as a photo interrupter that detects the drive amount.

  The AF processing unit 105 has a function of automatically focusing, and a contrast detection that detects a focus state using a TTL (through-the-lens) method and a high-frequency component of a signal indicating contrast on the image sensor 108. Use the method. The image sensor 108 functions as a light receiving unit or a photoelectric conversion unit that converts reflected light from the subject into an electrical signal. The A / D conversion unit 109 has a function of converting analog data into digital data, and includes a correlated double sampling (CDS) circuit that removes output noise of the image sensor 108 and a non-linear amplification circuit that is performed before A / D conversion. Including.

  The image processing unit 110 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D conversion unit 109. The image processing unit 110 performs predetermined calculation processing using the captured image data, and the system control unit 115 controls the AE processing unit 103, the AF processing unit 105, and the EF processing unit 107 based on the obtained calculation result. Control. Further, the image processing unit 110 has an electronic zoom function, and the electronic zoom function performs image conversion from an input image of the image sensor 108 to a display image on the operation display unit 117. As described above, the electronic zoom changes the zoom magnification by enlarging and displaying a part of the image signal. When the zoom lens is moved to the telephoto end and instructed to further telephoto, a part of the image signal is enlarged by electronic zoom to realize a higher magnification zoom.

  The WB processing unit 111 performs predetermined calculation processing on the captured image data, and performs TTL AWB (auto white balance) processing based on the obtained calculation result. The format conversion unit 112 converts the format of the image data into a predetermined format such as a JPEG format. The DRAM 113 includes a high-speed built-in memory (for example, a random access memory) and is used as a high-speed buffer as temporary image storage means or a working memory for image compression / decompression.

  The image recording unit 114 includes a recording medium such as a semiconductor memory and its interface. The system control unit 115 controls the system such as an imaging sequence and executes processes shown in FIGS. The VRAM 116 functions as an image display memory. In addition to image display, the operation display unit 117 displays a display for assisting operations, a display of a camera state, and a shooting screen and a focus detection area during shooting. The operation display unit 117 includes an LCD, an LED, a speaker, and the like.

  The operation unit 118 is used when the camera is operated from the outside. For example, a menu switch for performing various settings such as a shooting function of the camera 100 and a setting at the time of image reproduction, a zoom lever (zoom for instructing a zoom operation of the shooting lens 101) Instruction means), an operation mode changeover switch between a photographing mode and a reproduction mode, an electronic zoom setting on / off switch, and the like. Here, the zoom lever is a lever on which the user performs a zoom operation. The zoom lever can be set to a telephoto (Tele) side for enlarging an image and a wide angle (Wide) side for reducing an image. The zoom lever can take three states: zoom lever off, telephoto on, and wide angle on. The electronic zoom setting on / off switch sets whether to use the electronic zoom. When the electronic zoom setting is on, the electronic zoom operation is performed. When the electronic zoom setting is off, the electronic zoom operation is not performed.

  The posture detection sensor 119 is the posture of the camera 100, that is, erect (horizontal posture), inverted (upside down posture), tilted left (grip down posture), tilted right (grip up posture), tilted forward (lens down posture), rear A signal corresponding to the tilt (post-lens posture) is output. With this signal, the system control unit 115 can detect the posture of the camera 100. Further, the system control unit 115 rotates the image obtained by changing the photometric evaluation and the AF weighting based on the posture information from the posture detection sensor 119, or shooting the image in the vertical posture (left tilt posture, right tilt posture). To display the vertical position on the operation display unit 117.

  The main SW 120 is a switch for turning on the system. A mode SW 121 is a switch for setting shooting modes such as a program, a landscape, and a person. The first stroke switch SW1 to which 122 is attached is a switch for performing a shooting standby operation such as AF or AE, which is turned on by a half-press operation of a release switch (not shown). A second stroke switch SW2 denoted by reference numeral 123 is a photographing switch that is turned on by pressing the release switch halfway and starts a photographing operation (an image recording operation on a recording medium).

  FIG. 1B shows the arrangement of focus detection areas in the electronic camera 100 of the present embodiment. In this figure, reference numeral 10 denotes a shooting screen (shooting angle of view range). In the photographing screen 10, a focus detection area group in the middle, which includes a focus detection area 11 provided in the center and focus detection areas 12 and 13 provided on the left and right of the focus detection area 11, and upper and lower stages thereof. A total of nine focus detection areas (image areas) of the focus detection area groups 14 to 19 provided by three are provided.

  Hereinafter, the operation of the electronic camera 100 will be described with reference to FIG. Here, FIG. 2 is a flowchart for explaining the operation of the electronic camera 100.

  First, the system control unit 115 determines whether or not the main SW 120 is on (step S201). If the system control unit 115 determines that the main SW 120 is on (step S201), the system control unit 115 then determines whether the remaining capacity of the image recording unit 114 exists (step S202). If the system control unit 115 determines that the remaining capacity of the image recording unit 114 is 0 (step S202), the system control unit 115 warns that the remaining capacity is 0 (step S203) and returns to step S201. In step S203, the warning of the image recording unit 114 may be displayed on the operation display unit 117, a warning sound may be output from a voice output unit (not shown), or both may be performed.

  If the system control unit 115 determines that the remaining capacity of the image recording unit 114 is not 0 (step S202), the system control unit 115 performs a zoom operation (step S204). Hereinafter, the zoom operation in step S204 will be described with reference to FIG. FIG. 3 is a flowchart of the subroutine for the zoom operation.

  First, the system control unit 115 determines whether or not the zoom lever included in the operation unit 118 is operated to the telephoto (Tele) side (step S301). If the system control unit 115 determines that the zoom lever is operated to the telephoto side (step S301), the system control unit 115 determines whether the zoom position of the imaging lens 101 is at the telephoto end (step S302). If the system control unit 115 determines that the zoom position of the imaging lens 101 is not at the telephoto end (step S302), the system control unit 115 moves the zoom position of the imaging lens 101 to the telephoto end (step S303), and then returns to step S301. .

  On the other hand, if the system control unit 115 determines that the zoom position of the imaging lens 101 is at the telephoto end (step S302), the system control unit 115 determines whether the electronic zoom performed by the image processing unit 110 is the maximum magnification (step S304). If the system control unit 115 determines that the electronic zoom by the image processing unit 110 is not the maximum magnification (step S304), the system control unit 115 increases the magnification of the electronic zoom by the image processing unit 110 (step S305), and then returns to step S301. To do.

  On the other hand, when the system control unit 115 determines that the zoom lever is not operated to the telephoto side (step S301), or when it is determined that the electronic zoom by the image processing unit 110 is the maximum magnification (step S304). It is determined whether or not the zoom lever is operated to the wide angle side (step S306). If the system control unit 115 determines that the zoom lever is operated to the wide angle side (step S306), the system control unit 115 determines whether the zoom position of the imaging lens 101 is at the wide angle end (step S307). If the system control unit 115 determines that the zoom position of the imaging lens 101 is not at the wide-angle end (step S307), the system control unit 115 determines whether the image processing unit 110 is using the electronic zoom (step S308).

  If the system control unit 115 determines that the image processing unit 110 is using the electronic zoom (step S308), the system control unit 115 decreases the magnification of the electronic zoom (step S309), and then returns to step S306. On the other hand, if the system control unit 115 determines that the image processing unit 110 is not using the electronic zoom (step S308), the system control unit 115 moves the zoom position of the imaging lens 101 to the wide angle side (step S310), and then step S306. Return to

  On the other hand, when the system control unit 115 determines that the zoom lever is not operated to the wide angle side (step S306), or determines that the zoom position of the imaging lens 101 is at the wide angle end (step S307), The zoom position of the imaging lens 101 is stored in a calculation memory (not shown) built in the system control unit 115 (step S311).

  Returning to FIG. 2, the system control unit 115 determines whether or not the switch SW1 is on after the zoom operation (step S204) (step S205). If the system control unit 115 determines that the switch SW1 is off (step S205), the system control unit 115 determines whether the switch SW120 is on (step S206). If the system control unit 115 determines that the switch SW120 is on (step S206), the system control unit 115 returns to step S204.

  If the system control unit 115 determines that the switch SW120 is off (step S206), the system control unit 115 returns to step S201. On the other hand, when determining that the switch SW1 is on (step S205), the system control unit 115 instructs the AE processing unit 103 to perform AE processing from the output of the image processing unit 110 (step S207).

  Next, the system control unit 115 performs an AF operation (step S208). Hereinafter, the AF operation in step S208 will be described with reference to FIG. FIG. 4 is a flowchart of an AF operation subroutine. In the AF operation, the focus lens 104 is driven (scanned) between the infinite end and the closest end, and a high-frequency component of a signal obtained from the image sensor 108 during the scan (hereinafter referred to as “AF evaluation value”). Is performed by a method in which the position where the peak shows a focus lens position. The focus lens position is scanned for each of the nine focus detection areas 11 to 19, and different focus lens positions are determined as the focus lens positions in the focus detection areas corresponding to subjects with different distances.

  First, the system control unit 115 moves the focus lens 104 to the scan start position (step S401). In this embodiment, the scan start position is set to an infinite end. When the scan is started, the system control unit 115 includes the AF evaluation value for each focus detection area provided in the imaging screen and the position of the focus lens 104 from which the AF evaluation value is obtained in the system control unit 115. It stores in the calculation memory which does not (step S402). The position of the focus lens 104 is detected via the detection unit as a relative position from a predetermined reset position with the drive amount of the drive unit of the focus lens 104.

  Next, the system control unit 115 determines whether or not the position of the focus lens 104 is at the scan end position (step S403). In this embodiment, the scan end position is set to the closest end. If the system control unit 115 determines that the position of the focus lens 104 is not at the scan end position (step S403), the system control unit 115 moves the focus lens 104 by a predetermined amount in the closest direction (step S404).

If the system control unit 115 determines that the position of the focus lens 104 is at the scan end position (step S403), the focus detection result is obtained from the AF evaluation value stored in step S402 and the position of the focus lens 104 for each focus detection region. Determine the reliability of. Further, in the focus detection area determined to have satisfactory reliability, the position (focus lens position) of the focus lens 104 at which the AF evaluation value exhibits a peak is calculated (step S405). For example, the system control unit 115 determines the reliability by obtaining a reliability evaluation value Eval shown in Expression (1). Here, V _max and V _min are the maximum and minimum focus evaluation values in a certain focus detection area, and k is a normalization coefficient. Here, if the value of E _val is 1 or more, it is determined that the reliability in the focus detection region is high (hereinafter referred to as “◯” determination), and if it is less than 1, the reliability in the focus detection region is low. ) (Hereinafter referred to as x). The determined focus detection area is a focus detection area that can be focused (a focusable area).

E _val = k (V _max −V _min ) (1)
Next, the system control unit 115 determines whether or not the AF evaluation value shows the maximum value at the position of the focus lens 104 at the closest end for each focus detection area. (Step S406). Δdetermination indicates that a subject is present closer to the scan range.

  Next, when the posture of the camera 100 detected by the posture detection sensor 119 is erect, for example, the system control unit 115 sets the focus detection regions 11 to 11 in the upper and middle (first screen region) of the shooting screen. It is determined whether or not there is a focus detection region for ◯ in FIG. 16 (step S407). If the system control unit 115 determines that there is a focus detection area for determination in the upper and middle focus detection areas of the shooting screen (step S407), the system control unit 115 determines whether or not the shooting lens is at a zoom position where anti-blurring measures should be taken. Judgment is made (step S408). This is to prevent the blurring from deteriorating at a specific zoom position depending on the configuration of the photographing lens.

  If the system control unit 115 determines that the zoom position is at the position where the anti-blurring measure is taken (step S408), the central focus detection area 11 is determined to be ◯, and the first predetermined distance Y that is a function of the zoom position. In step S409, it is determined whether the first subject distance corresponding to the central focus detection area 11 is a long distance. This is because the image to be photographed is a distant view that is greatly affected by blurring, and whether or not the focus detection result necessary for performing focus adjustment in the central focus detection region 11 is a ◯ determination. Here, the subject distance is detected using the relationship that the closer to the infinite end the closer the focus lens 104 is to the subject, the farther the subject is, and the closer the subject is to the closest end. It can be calculated from the result.

  If the system control unit 115 determines YES in step S409, the object distance corresponding to the central focus detection region 11 is closer than the subject distance corresponding to the central focus detection region 11 among the focus detection regions determined in the upper middle stage of the shooting screen. It is determined whether there is a focus detection area corresponding to the subject distance on the side (step S410). This assumes the case where a commemorative photo or the like is taken with the landscape in the background. In this case, in order to focus on the pan focus control or the person, focus control on the central focus detection area 11 corresponding to the back is not performed.

  Here, the first predetermined distance Y that is determined to be a distant view in step S409 and the second predetermined distance X that serves as a reference for the difference between the subject distance corresponding to the central focus detection area in step S410 is a function of the zoom position. That is, the value changes according to the zoom position. This is because the depth of field changes depending on the zoom position.

  If it is determined NO in step S410, the system control unit 115 selects the central focus detection area 11 as an in-focus target area for driving the focus lens 104 and focusing (step S411). Next, the system control unit 115 drives the focus lens 104 to a position (focusing lens position) corresponding to the selected central focus detection area 11 where the AF evaluation value obtained in step S405 reaches a peak. Focus control for the central focus detection region 11 is performed (step S412).

  Hereinafter, an example of the focus detection area selection described in steps S409 and S410 will be described with reference to FIG. FIG. 5 is a schematic diagram for explaining the selection of the focus detection area. For simplicity, as the focus detection area, the center focus detection area 11 in the middle of the shooting screen, the left focus detection area 12, and the right focus detection area 12 are shown. Only three focus detection areas 13 are shown. In FIG. 5, the subject distance A (the distance to the desk lamp S) corresponding to the central focus detection area 11 is longer than the first predetermined distance Y. When the central focus detection region 11 is “good”, the left focus detection region 12 corresponding to the subject distance α (distance to the person P1) closer to the second predetermined distance X than the subject distance A is “good”. It is determined whether or not. If the left focus detection area 12 is determined as ◯, the left focus detection area 12 is selected as a focus target position, the focus lens 104 is driven, and focus control on the left focus detection area 12 is performed.

  On the other hand, if the left focus detection area 12 is x, the right focus detection area 13 is not closer than the second predetermined distance X from the subject distance A, so the center focus detection area 11 is selected as the focus target position, Focus control for the central focus detection area 11 is performed.

  It should be noted that both the left and right focus detection areas 12 and 13 are “good”, and the subject distances corresponding to the left and right focus detection areas 12 and 13 are both closer than the subject distance A by a second predetermined distance X or more. In the case of the subject distance on the side, the focus detection area corresponding to the closest object distance among these focus detection areas 12 and 13 is selected as the focus target area.

  In addition, although the determination targets in steps S407 and S410 in FIG. 4 are the upper and middle focus detection areas, this is an example, and the determination targets in steps S407 and S410 are based on the detection result by the posture detection sensor 119. Be changed. In accordance with this, the focus detection area to be determined in step S414 described later is also changed from the lower stage.

  Returning to FIG. 4, when the system control unit 115 determines that the zoom position is not to be corrected for blurring (step S <b> 408), when NO is determined in step S <b> 409, or when YES is determined in step 410, Among the upper and middle circle determination focus detection areas, the focus detection area where the focus lens position obtained in step S405 is closest is selected as the focus target area (step S413).

  On the other hand, if the system control unit 115 determines that the upper and middle focus detection areas 11 to 16 do not have the o determination focus detection area (step S407), the system control unit 115 depends on the attitude of the camera 100 detected by the attitude detection sensor 119. Then, it is determined whether or not there is a circle determination focus detection region in the lower focus detection regions 17 to 19 (step S414).

  When the lower focus detection areas 17 to 19 include the o determination focus detection area (step S414), the focus detection area in which the focus lens position obtained in step S405 is closest to the lower o determination focus detection area is selected. The focus target area is selected (step S415), and the process proceeds to step S412.

  On the other hand, when the system control unit 115 determines that the lower focus detection areas 17 to 19 do not have the ○ determination focus detection area (step S414), the lower focus detection areas 17 to 19 are determined to be Δ in step S406. It is determined whether or not there is a focus detection area (step 416). When the system control unit 115 determines that there is a Δ determination region in the lower focus detection region (step S416), the system control unit 115 moves the focus lens 104 to the closest end (step S417), and proceeds to step S412.

  On the other hand, when the system control unit 115 determines that there is no Δ determination region in the lower focus detection region (step S416), the reliability evaluation value Eval of the central focus detection region obtained in step S405 is greater than or equal to a predetermined value. Whether or not (step S418). If the system control unit 115 determines that the reliability evaluation value Eval is greater than or equal to a predetermined value (step S418), the system control unit 115 proceeds to step S417, and if it is determined that the reliability evaluation value Eval is not equal to or greater than the predetermined value (step S418), it is preset as a fixed point. The focus lens 104 is driven to the set position (step S419).

  Returning to FIG. 2 again, after the AF operation (step S208), the system control unit 115 determines whether or not the second stroke switch SW2 is ON (step S209). If the system control unit 115 determines that the second stroke switch SW2 is off (step S209), the system control unit 115 determines whether the first stroke switch SW1 is on (step S210). If the system control unit 115 determines that the first stroke switch SW1 is on (step S210), the system control unit 115 returns to step S209. If the system control unit 115 determines that the first stroke switch SW1 is off (step S210), the system control unit 115 returns to step S204.

  On the other hand, if the system control unit 115 determines that the second stroke switch SW2 is on (step S209), the system control unit 115 performs a photographing operation (step S211). Hereinafter, the photographing operation (step S211) will be described with reference to the flowchart of FIG. Here, FIG. 6 is a flowchart of a subroutine of the photographing operation (step S211).

  First, the system control unit 115 measures subject brightness (step S601). Next, the system control unit 115 performs exposure on the image sensor 108 by controlling the charge accumulation time according to the subject brightness measured in step S601 and controlling the aperture and the shutter 102 (step S602). An image formed on the surface of the image sensor 108 is photoelectrically converted into an analog signal and sent to the A / D converter 109. Next, the analog signal is converted into a digital signal by the A / D conversion unit 109 after preprocessing such as output noise removal of the image sensor 108 and nonlinear processing (step S603).

  Next, the white balance of the output signal from the A / D conversion unit 109 is adjusted by the image processing unit 110 by the WB processing unit 111 to obtain an appropriate output image signal (step S604). Next, the output image signal is converted into the JPEG format or the like by the format conversion unit 112 and temporarily stored in the DRAM 113 (step S605). Next, the data in the DRAM 113 is transferred and recorded by the image recording unit 114 to a memory in the camera or a recording medium such as a memory card attached to the camera 100 (step S606).

  Returning to FIG. 2 again, the system control unit 115 determines whether or not the remaining capacity of the image recording unit 114 exists (step S212). If the system control unit 115 determines that the remaining capacity of the image recording unit 114 is 0 (step S212), the system control unit 115 warns that the remaining capacity is 0 (step S203) and returns to step S201. On the other hand, if the system control unit 115 determines that the remaining capacity of the image recording unit 114 is not 0 (step S212), the system control unit 115 determines whether the second stroke switch SW2 is on (step S213). If the system control unit 115 determines that the second stroke switch SW2 is OFF (step S213), the system control unit 115 returns to step S209. On the other hand, if the system control unit 115 determines that the switch SW2 is on, it repeats step S213.

  According to the electronic camera 100 of the present embodiment described above, when shooting a distant view such as a landscape that is particularly susceptible to blurring in the center of the shooting screen, it is more than the subject distance corresponding to the focus detection area at the center of the screen. Focus control is performed on a focus detection area corresponding to a subject close to a predetermined distance. As a result, it is possible to ensure the focusing accuracy for the subject (main subject) corresponding to the focus detection area provided outside the center of the shooting screen. That is, the focus adjustment that effectively reduces the influence of blurring becomes possible.

  In the above embodiment, the case where one focus detection area is provided at the center of the shooting screen has been described. However, a plurality of focus detection areas are provided in an area having a predetermined size including the center of the screen. A “focus detection area” may be provided, and a plurality of focus detection areas may be provided around the focus detection area.

It is a block diagram which shows schematic structure of the electronic camera of the Example of this invention. It is a conceptual diagram which shows the focus detection area | region in the electronic camera shown in FIG. It is a flowchart which shows operation | movement of the electronic camera shown in FIG. 3 is a flowchart of a zoom operation subroutine shown in FIG. 2. 3 is a flowchart of an AF operation subroutine shown in FIG. 2. FIG. 5 is a schematic diagram for explaining selection of a focus detection area in the AF operation shown in FIG. 4. 3 is a flowchart of a shooting operation subroutine in FIG. 2. It is an example of the scene which brings about a blur in the conventional digital camera.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Electronic camera 101 Shooting lens 105 AF process part 108 Image pick-up element 115 System control part 119 Posture detection sensor

Claims (11)

A focus detection means for detecting a focus state in a plurality of focus detection areas provided in the photographing screen;
A selection unit that selects a focus target region for focusing the photographing lens based on a detection result by the focus detection unit among the plurality of focus detection regions;
The selection means includes a second subject to a second subject whose first subject distance to the first subject is longer than a first predetermined distance and is outside the first subject on the photographing screen. When the subject distance is closer than the first subject distance by a second predetermined distance or more, a focus detection area corresponding to the second subject is selected as the focus target area.   When there are a plurality of the second subjects, the selection unit selects, as the focus target position, a focus detection area corresponding to a subject having a subject distance shorter than other subjects among the plurality of second subjects. The imaging apparatus according to claim 1, wherein:   When the first subject distance is farther than the first predetermined distance and the second subject distance is not closer than the second predetermined distance than the first subject distance, the selection means The imaging apparatus according to claim 1, wherein a focus detection area corresponding to one subject is selected as the focus target area.   The selection means, when the first subject distance is closer than the first predetermined distance, selects a focus detection area corresponding to the subject with the closest subject distance as the focus target position. The imaging device according to any one of 1 to 3.   5. The photographing apparatus according to claim 1, wherein the first and second predetermined distances are changed according to a focal length of the photographing lens.   6. The photographing apparatus according to claim 1, further comprising a driving unit that drives a focus lens so that the photographing lens is focused on the focus target area. A focus detection means for detecting a focus state in a plurality of image areas provided in the shooting screen;
A selection unit that selects a target region for focusing the photographing lens based on a detection result by the focus detection unit among the plurality of image regions;
The selection means is configured such that a first subject distance to a first subject displayed in a first screen area on the photographing screen is longer than a first predetermined distance and is on the photographing screen more than the first subject. When the second subject distance to the second subject displayed in the outer second screen area is closer than the first subject distance by a second predetermined distance or more, it corresponds to the second subject. An imaging apparatus, wherein an image area is selected as the focus target area.   The selection means, when there is no focusable area in the first screen area, selects a focus detection area with the closest subject distance in the second screen area as the focus target position. The imaging device according to claim 7. Having an attitude detecting means for detecting an attitude of the photographing apparatus;
9. The photographing apparatus according to claim 7, wherein the selection unit changes the first and second screen areas in accordance with the detection result of the posture. A focus detection step for detecting a focus state in a plurality of focus detection areas provided in the shooting screen;
A selection step of selecting a focus target region for focusing the photographing lens based on a detection result of the focus detection step among the plurality of focus detection regions;
In the selection step, the second subject to the second subject that is farther than the first predetermined distance and is outside the first subject on the shooting screen is the first subject distance to the first subject. When the subject distance is closer than the first subject distance by a second predetermined distance or more, a focus detection region corresponding to the second subject is selected as the focus target region. A focus detection step for detecting a focus state in a plurality of image areas provided in the shooting screen;
A selection step of selecting a focus target region for focusing the photographing lens based on a detection result of the focus detection step among the plurality of image regions;
In the selection step, the first subject distance to the first subject displayed in the first screen area on the photographing screen is longer than a first predetermined distance and is on the photographing screen than the first subject. When the second subject distance to the second subject displayed in the outer second screen area is closer than the first subject distance by a second predetermined distance or more, it corresponds to the second subject. A focus adjustment method, wherein an image area is selected as the focus target area.