Patent Publication Number: US-2013250165-A1

Title: Method and apparatus for applying multi-autofocusing (af) using contrast af

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/983,951, filed Jan. 4, 2011, which claims the priority benefit of Korean Patent Application No. 10-2010-0001317, filed on Jan. 07, 2010, in the Korean Intellectual Property Office, the disclosure of both which are incorporated herein in their entirety by reference. 
    
    
     BACKGROUND 
     Embodiments relate to applying multi-autofocusing (AF) in digital photographing apparatuses. More particularly, the embodiments relate to a method of applying multi-AF by using a contrast AF in digital photographing apparatuses. 
     In conventional multi point-autofocusing (hereinafter, multi-AF) based on a contrast AF method, a focus lens is moved to an infinite location and then scans the entire region between the focus lens and a subject. Thereafter, the multi-AF method is applied. Accordingly, detection of a main subject is possible only after the entire region is scanned. Thus, AF speed is reduced. 
     In a conventional method using a multi-AF method by mixing an external light AF method and a contrast AF method, a scan time required to apply the contrast AF method may be decreased, but it takes time to perform the external light AF method. Thus, the overall AF speed is still low. In addition, the size and cost of a camera increases in order to achieve the external light AF method. 
     SUMMARY 
     Embodiments include a digital photographing apparatus that performs a high-speed multi-autofocusing (AF) method by using contrast AF. 
     According to an embodiment, a digital photographing apparatus that applies a multi-autofocusing (AF) function using a contrast AF method comprises: a photographing lens; an image pickup unit that converts image light obtained from a subject through the photographing lens into an electrical signal to generate an image signal; a driving unit that drives a focus lens of the photographing lens; a calculation unit that calculates an AF evaluation value by performing AF on the image signal; a multi-AF detection unit that detects a peak of an AF evaluation value of each of a plurality of multi-points into which a captured image formed by the image signal is divided; a scanning unit that scans peaks of a central multi-point or a nearest multi-point of the captured image if at least one of the peaks of the central multi-point or the nearest multi-point is not detected; and a main subject determination unit that selects the peak of the central multi-point or nearest multi-point according to a predetermined multi-AF method, determines a subject corresponding to the multi-point where the peak is selected as a main subject, and performs the contrast AF on the main subject. 
     The scanning unit may perform scanning until both peaks of the central multi-point and the nearest multi-point are detected. 
     When the peak of the central multi-point is not detected even when the peak of the nearest multi-point is detected, the scanning unit may invert a moving direction of the focus lens to an infinite direction. 
     When the peak of the nearest multi-point is not detected even when the peak of the central multi-point is detected, the scanning unit may invert a moving direction of the focus lens to a Near direction. 
     The scanning unit may not scan a region from which a peak is not likely to be detected during scanning in a Near direction or an infinite direction, wherein the possibility that a peak is detected may be determined according to whether an AF evaluation value monotonically increases or monotonically decreases at a synchronization position of a lens. 
     When the peak of the central multi-point is not detected even after scanning is performed until a predetermined magnification, the scanning unit may perform scanning only until the predetermined magnification and may no longer scan a peak of the central multi-point. 
     The magnification may be a ratio of a size of a subject to a size of the captured image in the image pickup unit. 
     The main subject determination unit may determine a subject corresponding to the peak of the nearest multi-point as the main subject. 
     The digital photographing apparatus may provide a still picture mode and a moving picture mode. 
     A still picture mode may begin by scanning in the Near direction, and a moving picture mode may begin by scanning in the infinite direction. 
     According to another embodiment, a digital photographing apparatus that applies a multi-autofocusing (AF) function using a contrast AF method comprises: a scanning unit that scans to a central multi-point or a nearest multi-point of a captured image when at least one of a peak of the central multi-point and a peak of the nearest multi-point is not detected; and a main subject determination unit that selects the peak of the central multi-point or nearest multi-point detected by the scanning unit according to a predetermined multi-AF method and determines a subject corresponding to the region where the peak is selected as a main subject, and performs an AF based on the contrast AF method. 
     The scanning unit may perform scanning until both peaks of the central multi-point and the nearest multi-point are detected. 
     When the peak of the central multi-point is not detected even when the peak of the nearest multi-point is detected, the scanning unit may invert a moving direction of the focus lens to an infinite direction and perform scanning in the infinite direction. 
     When the peak of the nearest multi-point is not detected even when the peak of the central multi-point is detected, the scanning unit may invert a moving direction of the focus lens to a Near direction and perform scanning in the Near direction. 
     The scanning unit may not scan a region from which a peak is not likely to be detected during scanning in the Near direction or the infinite direction, wherein the possibility that a peak is detected may be determined according to whether an AF evaluation value monotonically increases or monotonically decreases at a synchronization position of a lens. 
     When the peak of the central multi-point is not detected even when scanning was performed until a predetermined magnification, the scanning unit may perform scanning only until the predetermined magnification and may no longer scan a peak of the central multi-point. 
     The magnification may be a ratio of a size of a subject of the nearest multi-point to a size of the captured image in the image pickup unit. 
     The magnification may be within a range from 1/60 to 1/100. 
     The main subject determination unit may determine a subject corresponding to the peak of the nearest multi-point as the main subject. 
     The digital photographing apparatus may provide a still picture mode and a moving picture mode. 
     A still picture mode may begin by scanning in the Near direction, and a moving picture mode may begin by scanning in the infinite direction. 
     Another embodiment includes a method of applying a multi-AF function using a contrast AF method in a digital photographing apparatus comprising a photographing lens, an image pickup unit that converts image light obtained from a subject through the photographing lens into an electrical signal to generate an image signal, a driving unit that drives a focus lens of the photographing lens, and a calculation unit that calculates an AF evaluation value by performing AF detection on the image signal. The method comprises: detecting a peak of an AF evaluation value of each of a plurality of multi-points into which a captured image formed by the image signal is divided; scanning a central multi-point or a nearest multi-point of the captured image when at least one of the peaks of the central multi-point and the nearest multi-point is not detected; and selecting the peak of the central multi-point or nearest multi-point detected in the scanning according to a predetermined multi-AF method and determining a subject corresponding to the selected peak as a main subject and performing the contrast on the main subject. 
     Another embodiment includes a method of applying a multi-AF method in a contrast AF method in a digital photographing apparatus. The method comprises: scanning a central multi-point or a nearest multi-point of a captured image when at least one of a peak of the central multi-point and a peak of the nearest multi-point is not detected; and selecting the peak of the central multi-point or nearest multi-point detected in the scanning according to a predetermined multi-AF method and determining a subject corresponding to the selected peak as a main subject and performing the contrast AF on the main subject. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages will become more apparent by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  is a schematic diagram of a digital photographing apparatus, according to an embodiment; 
         FIG. 2  is a block diagram of a camera control unit included in the digital photographing apparatus according to the embodiment illustrated in  FIG. 1 ; 
         FIG. 3A  illustrates a multi-autofocusing (AF) region, namely, an example of a focus detection region in which focus detection is performed during still picture photographing; 
         FIG. 3B  illustrates an example in which subjects exist within the multi-AF region illustrated in  FIG. 3A ; 
         FIGS. 4A and 4B  illustrate a multi-AF region, namely, an example of a focus detection region in which focus detection is performed during moving picture photographing; 
         FIG. 5  illustrates an exemplary multi-AF region in which regions partially overlap one another; 
         FIG. 6  illustrates a table for explaining a near and central mixed focus selection method conventionally used in a phase difference AF method; 
         FIGS. 7A and 7B  illustrate an exemplary multi-AF method that adaptively uses a nearest multi-point focus selection method or a central multi-point focus selection method; 
         FIG. 8  is an exemplary graph for describing detection of a peak value of AF evaluation values in a contrast AF method; 
         FIG. 9  illustrates an example of a method of determining a range of potential peak (RPP); 
         FIG. 10  is a schematic diagram of an interchangeable-lens digital photographing apparatus, according to another embodiment; 
         FIG. 11  is a schematic diagram of a digital photographing apparatus having a lens and a body unit integrally formed in one body, according to another embodiment; 
         FIG. 12  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a central multi-point and a nearest multi-point are both detected, according to an embodiment; 
         FIG. 13  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the central multi-point is not detected because its contrast is low, according to an embodiment; 
         FIG. 14  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a subject exists at a location nearer to a digital photographing apparatus than a nearest location detectable by the digital photographing apparatus is and when a magnification of the central multi-point is greater than 1/60, according to an embodiment; 
         FIG. 15  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the central multi-point fails to be detected and a subject existing in the near region is nearer to the photographer than the nearest location detectable by the digital photographing apparatus, according to an embodiment; 
         FIG. 16  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a magnification of a subject of the central multi-point is less than 1/60, according to an embodiment; 
         FIG. 17  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the central multi-point is not detected because its contrast is low, and when a range detection point ∞z is closer to ∞ than the point 1/60 is, according to an embodiment; 
         FIG. 18  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a subject in the central multi-point is detected at a location ∞ and the point  1 / 60  is closer to ∞ than the range detection point ∞z is, according to an embodiment; 
         FIG. 19  illustrates application of the multi-AF method illustrated in  FIG. 7  in the contrast AF method when all subjects exist at the location ∞, according to an embodiment; 
         FIG. 20  illustrates an embodiment in which the magnification of the central multi-point is greater than 1/60; 
         FIG. 21  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the contrast of the central multi-point cannot be detected, according to an embodiment; 
         FIG. 22  illustrates an embodiment in which a subject in a near region exists nearer to the photographer than the nearest location detectable by the digital photographing apparatus is and a subject in a central multi-point exists at the location ∞; 
         FIG. 23  is a flowchart of a driving process of a digital photographing apparatus, according to an embodiment; 
         FIGS. 24A and 24B  are flowcharts of an operation of AF detection in the digital photographing apparatus when the shutter release button is half pressed in the live view display operation S 2350  of  FIG. 23 , according to an embodiment; 
         FIG. 25  is a flowchart of an end determination process included in the operation of the digital photographing apparatus illustrated in  FIG. 24A , according to an embodiment; 
         FIGS. 26A ,  26 B, and  26 C are flowcharts of an operation of the digital photographing apparatus when the shutter release button is fully pressed, according to an embodiment; 
         FIG. 27  illustrates a live view operation performed by a camera which is an example of a digital photographing apparatus, according to an embodiment; 
         FIGS. 28A and 28B  are flowcharts of an operation of an all-in-one camera which is an example of an all-in-one digital photographing apparatus, according to an embodiment; 
         FIG. 29  is a flowchart of an operation of the digital photographing apparatus when the shutter release button is fully pressed, according to an embodiment; 
         FIGS. 30A and 30B  are flowcharts of applying the multi-AF method illustrated in  FIGS. 7A and 7B  to the contrast AF method in a moving picture mode of the digital photographing apparatus, according to an embodiment; 
         FIG. 31  is a flowchart of a multi-AF method, according to an embodiment; 
         FIG. 32  is a flowchart of a multi-AF method, according to another embodiment; and 
         FIG. 33  is a flowchart of a method of applying a multi-AF method to the contrast AF method in the digital photographing apparatus, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments will now be described more fully with reference to the accompanying drawings. 
     Structure and Operation of Digital Photographing Appartus 
       FIG. 1  is a schematic diagram of a digital photographing apparatus  1 , according to an embodiment. 
     Referring to  FIG. 1 , the digital photographing apparatus  1  according to the present embodiment includes an interchangeable photographing lens unit  100  and a body unit  200 . The interchangeable photographing lens unit  100  may detect whether a focus of a captured image is in an in-focus state or not, and the body unit  200  includes a function that facilitates the interchangeable photographing lens unit  100  to drive a focus lens  104 . 
     The interchangeable photographing lens unit  100  (hereinafter, referred to as a lens  100 ) includes an image-forming optical system  101 , a zoom lens position detecting sensor  103 , a lens driving actuator  105 , a focus lens position detecting sensor  106 , an iris driving actuator  108 , a lens control unit  110 , and a lens mount  109 . 
     The image-forming optical system  101  may include a zoom lens  102  that performs zoom control, a focus lens  104  that changes a focusing position, and an iris  107 . Each of the zoom lens  102  and the focus lens  104  may include a lens group. 
     The zoom lens position detecting sensor  103  and the focus lens position detecting sensor  106  detect the positions of the zoom lens  102  and the focus lens  104 , respectively. Timing of when the position of the focus lens  104  is detected may be set by the lens control unit  110  or a camera control unit  209 , which is to be described later. For example, the timing of when the position of the focus lens  104  is detected may be when AF detection with respect to an image signal is performed. 
     The lens driving actuator  105  and the iris driving actuator  108  drive the focus lens  104  and the iris  107 , respectively, under the control of the lens control unit  110 . In particular, the lens driving actuator  105  drives the focus lens  104  along an optical axis. 
     The lens control unit  110  includes a first timer  111  that measures time, and a lens memory  112  that stores information about lens characteristics. The lens control unit  110  transmits information about the position of the focus lens  104  to the body unit  200 . If the position of the focus lens  104  is changed or the camera control unit  209  requests position information about the focus lens  104 , the lens control unit  110  may transmit the information about the position of the focus lens  104  to the body unit  200 . The first timer  111  may be reset by a reset signal output from the body unit  200 , and the lens  100  and the body unit  200  may be synchronized with each other by the reset operation. 
     The lens mount  109  includes a lens-side communication pin and is engaged with a camera-side communication pin, which is to be described later, so as to serve as a transport path for data, control signals, and the like. 
     A structure of the body unit  200  will now be described. 
     The body unit  200  may include a viewfinder (for example, an electronic viewfinder (EVF))  201 , a shutter  203 , an imaging device  204 , an imaging device control unit  205 , a display  206 , a manipulation unit  207 , a camera mount  208 , and a camera control unit  209 . 
     The viewfinder  201  may include a liquid crystal display (LCD)  202  built therein, and may view a captured image in real time. 
     The shutter  203  determines a time during which light is applied to the imaging device  204 , that is, an exposure time. 
     The imaging device  204  converts light that has passed through the image-forming optical system  101  of the lens  100  into an image signal. The imaging device  204  may include a plurality of photoelectric conversion units arranged in a matrix, and a vertical or/and horizontal transport path for moving electric charge from the photoelectric conversion units in order to read out an image signal. The imaging device  204  may be a charge coupled device (CCD) sensor, a complementary metal oxide semiconductor (CMOS) sensor, or the like. 
     The imaging device control unit  205  generates a timing signal and controls the imaging device  204  to capture an image in synchronization with the timing signal. When charge accumulation in each scan line is completed, the imaging device control unit  205  controls horizontal image signals to be sequentially read. The horizontal image signals are used by the camera control unit  209  during AF detection. 
     The display  206  displays various images and a variety of information. The display  206  may be an organic light emitting device (OLED) or the like. 
     Users use the manipulation unit  207  to input various commands in order to manipulate the digital photographing apparatus  1 . The manipulation unit  207  may include various buttons, switches, and dials, such as a shutter release button, a main switch SM, a mode dial, a menu button, etc. In  FIG. 1 , S 1  represents the half-pressing operation of the shutter release button, S 2  represents the full-pressing operation of the shutter release button, and SM represents a main switch. 
     The camera control unit  209  performs AF detection with respect to the image signal generated by the imaging device  204  in order to calculate an AF evaluation value. In addition, the camera control unit  209  stores an AF evaluation value obtained at every AF detection time depending on the timing signal generated by the imaging device control unit  205 , and calculates a focusing position by using lens position information received from the lens  100  and the stored AF evaluation value. A result of the calculation of the focusing position is transmitted to the lens  100 . 
     The camera mount  208  includes the aforementioned camera-side communication pin. 
     Schematic operations of the lens  100  and the body unit  200  will now be described. 
     When a subject is photographed, the main switch SM included in the manipulation unit  207  is manipulated to start an operation of the digital photographing apparatus  1 . The digital photographing apparatus  1  performs a live view display as follows. 
     Image light of the subject, which has passed through the image-forming optical system  101 , is incident upon the imaging device  204 . At this time, the shutter  203  is in an open state. The incident image light of the subject is converted into an electrical signal in the imaging device  204 , and thus an image signal for the subject is generated. The imaging device  204  operates according to the timing signal generated by the imaging device control unit  205 . The image signal for the subject is converted into displayable data in the camera control unit  209 , and the displayable data is output to the viewfinder  201  and the display  206 . This process is referred to as a live view display. During the live view display, live view images are consecutively displayed as a moving picture. 
     After the live view display is performed, when the shutter release button included in the manipulation unit  207 , is half pressed (S 1 ), the digital photographing apparatus  1  starts an AF operation. The AF operation is performed using the image signal generated by the imaging device  204 . In a contrast AF method, a focusing position is calculated from an AF evaluation value associated with a contrast value, and the lens  100  is driven based on a result of the calculation. The AF evaluation value is calculated by the camera control unit  209 . The camera control unit  209  calculates information used to control the focus lens  104  from the AF evaluation value and transmits the information to the lens control unit  110  via the lens-side and camera-side communication pins included in the lens mount  109  and the camera mount  208 . 
     The lens control unit  110  controls the lens driving actuator  105  to drive the focus lens  104  along the optical axis, on the basis of the received information, thereby performing an AF operation. The position of the focus lens  104  is monitored by the focus lens position detecting sensor  106  so that feedback control is achieved. 
     When the focal length of the zoom lens  102  has been varied by manipulation by a user, the position of the zoom lens  102  is detected by the zoom lens position detecting sensor  103 , and the lens control unit  110  performs the AF operation again by changing AF control parameters of the focus lens  104 . The AF control parameters are stored as unique information about the lens  100  in the lens memory  112 . When the position of a zoom lens group is changed, conversion coefficients of a focus lens driving amount and a focus deviation amount of a photographing lens are changed. The AF control parameters include the changed conversion coefficients of the focus lens driving amount and the focus deviation amount of the photographing lens. 
     When a subject image is in-focus by the above-described operation, the shutter release button is fully pressed (S 2 ) after a half-pressing operation (S 1 ), and thus the digital photographing apparatus  1  performs an exposure operation. At this time, the camera control unit  209  completely closes the shutter  203  and transmits all obtained measured-light information as iris control information to the lens control unit  110 . The lens control unit  110  controls the iris driving actuator  108  on the basis of the iris control information and tightens the iris  107  with a suitable iris value. The camera control unit  209  controls the shutter  203  on the basis of the measured-light information and opens the imaging device  204  by a suitable exposure time to capture the subject image. In a moving picture mode, the digital photographing apparatus  1  records a moving picture by full-pressing the shutter release button one time, and the recording is concluded when the shutter release button is fully pressed again. 
     The captured subject image undergoes image signal processing and compression and is stored in a memory card  212  (see  FIG. 2 ). Simultaneously, the captured subject image is output to the viewfinder  201  and the display  206 , both of which display the subject. This captured subject image is referred to as a quick view image. Examples of the display  206  include an OLED. A series of photographing operations are completed according to the above-described process. 
     Moving pictures are captured and simultaneously undergo a moving picture compression process and are stored in the memory card  212  (see  FIG. 2 ). During moving picture photography, live view display instead of quick view display is performed. 
     A still picture mode and a moving picture mode may be changed using the manipulation unit  207 . At the half-pressing operation S 1 , both the still picture mode and the moving picture mode perform the same function. At the full-pressing operation S 2 , a still picture is captured in the still picture mode and moving picture recording starts in the moving picture mode. 
     Structure and Operation of Camera Control Unit 
       FIG. 2  is a block diagram of the camera control unit  209  included in the digital photographing apparatus according to the embodiment illustrated in  FIG. 1 . 
     Referring to  FIG. 2 , the camera control unit  209  according to the present embodiment may include a pre-processor  220 , a signal processor  221 , a signal compression and expansion unit  222 , a display controller  223 , a central processing unit (CPU)  224 , a memory controller  225 , an audio controller  226 , a card controller  227 , a second timer (not shown), and a main bus  230 . 
     The camera control unit  209  transmits a variety of instructions and data to its components via the main bus  230 . 
     The pre-processor  220  receives the image signal generated by the imaging device  204  and performs Auto White Balance (AWB), Auto Exposure (AE), and Auto Focus (AF) operations. In other words, an AF evaluation value for focus control, an AE evaluation value for exposure control, an AWB evaluation value for white balance control, and the like are calculated. The AF evaluation value may include a horizontal AF evaluation value that represents a horizontal contrast, and a vertical AF evaluation value that represents a vertical contrast. The horizontal AF evaluation value is calculated from a horizontal image signal received directly from the imaging device  204 . On the other hand, the vertical AF evaluation value may be calculated from a vertical image signal into which the horizontal image signal is converted after being stored in a memory  210 , which will be described later. In other words, the pre-processor  220  may be an example of an AF evaluation value calculation unit. 
     The signal processor  221  performs a series of image signal processing operations, such as gamma correction, in order to form a live view image or a captured image that is displayable on a display. 
     The signal compression and expansion unit  222  compresses and expands the image signal on which the image signal processing has been performed. During compression, the image signal is compressed by using a compression format, for example, a JPEG compression format or an H.264 compression format. An image file including image data generated by the compression is transmitted to and stored in the memory card  212 . 
     The display controller  223  controls images to be output to the LCD  202  of the viewfinder  201  or to the display  206 . 
     The CPU  224  controls all component operations. In the digital photographing apparatus  1  of  FIG. 1 , the CPU  224  communicates with the lens  100 . 
     The memory controller  225  controls the memory  210  for temporarily storing a captured image or data, such as associated information, and the audio controller  226  controls a microphone or speaker  211 . The card controller  227  controls the memory card  212  for storing the captured image. 
     The operation of the camera control unit  209  will now be briefly described. 
     When the CPU  224  detects that the main switch SM (see  FIG. 1 ) of the manipulation unit  207  has been manipulated, the CPU  224  operates the imaging device control unit  205  via the pre-processor  220 . The imaging device control unit  205  outputs the timing signal to operate the imaging device  204 . When the image signal is input from the imaging device  204  to the pre-processor  220 , AWB and AE operations are performed. Results of the AWB and AE operations are fed back to the imaging device control unit  205  so that the imaging device  204  may obtain an image signal having suitable color output and suitable exposure. 
     When the operation of the digital photographing apparatus  1  resumes, live view display is performed. The camera control unit  209  inputs an image signal obtained by a photographing operation under suitable exposure conditions to the pre-processor  220 , thereby calculating an AE evaluation value or the like. An image signal for use in live view display is applied directly to the signal processor  221  without passing through the main bus  230 , and image signal processing such as pixel interpolation is performed on the received image signal. An image subjected to the image signal processing is displayed on the LCD  202 , the display  206 , and the like, via the main bus  230  and the display controller  223 . The live view display is basically updated at a speed of 60 fps (frames per second), but this should not be construed as limiting. The live view display may be updated at 30 fps, 120 fps, or the like. The update speed may be set by the CPU  224  on the basis of a light measurement result, AF conditions, or the like, and the update speed may be changed according to a timing signal in the imaging device control unit  205 . 
     When the shutter release button is half pressed (S 1 ), the CPU  224  detects an input of a signal out of the half-pressing operation S 1  and instructs the lens control unit  110  to start driving the focus lens  104  for an AF operation, via the camera-side and lens-side communication pins included in the camera mount  208  and the lens mount  109 . In another embodiment, when the CPU  224  detects the input of the signal out of the half-pressing operation S 1 , the CPU  224  may directly control the focus lens  104  to be driven in order to perform an AF operation. In other words, the CPU  224  may be an example of a main control unit. An AF output according to the degree to which the focus lens  104  is changed is shown in  FIG. 8 , and a detailed description thereof will be described later with reference to  FIG. 8 . 
     The CPU  224  acquires the image signal from the imaging device  204 , and the pre-processor  220  calculates the AF evaluation value of the image signal. The AF evaluation value is calculated according to the motion of the focus lens  104 . A position (a position where the AF evaluation value is at a maximum) of the focus lens  104  is calculated from a change in the AF evaluation value, and the focus lens  104  is moved to the calculated position. This series of operations performed by the CPU  224  constitute an AF operation, and a live view image is continuously displayed even during the AF operation. An image signal used to form a live view image is the same as an image signal used to calculate an AF evaluation value. 
     In the digital photographing apparatus  1  using the lens  100  illustrated in  FIG. 1 , during an AF operation, the lens  100  communicates with the body unit  200  via the camera-side and lens-side communication pins installed in the camera mount  208  and the lens mount  109 , and the camera-side and lens-side communication pins operate through serial communication in order to transmit lens information or control information. Position information about the focus lens  104 , corresponding to an AF evaluation value, is also transmitted. 
     When the shutter release button is fully pressed (S 2 ), the AF operation is stopped in the still picture mode, but the AF operation continues in the moving picture mode. Thus, the AF operation is consecutively repeated even after the digital photographing apparatus  1  is in-focus. In other words, continuous AF is used in the moving picture mode. A continuous AF mode denotes a mode in which a digital photographing apparatus continuously adjusts focus even when the S 1  operation has not been performed. However, in the continuous AF mode, the focus lens  104  operates slowly in order to minimize its influence, in terms of sounds or a change in a viewing angle, upon moving picture photographing. 
     An AF region of which an AF evaluation value is calculated during an AF operation will now be described with reference to  FIGS. 3A and 3B . 
     Multi-AF (Detection of Main Subject) 
       FIG. 3A  illustrates a multi-AF region, namely, an example of a focus detection region in which focus detection is performed during still picture photographing. The multi-AF region includes multi-AF points (hereinafter, referred to as multi-points) e 1  through e 15 . Multi-AF may determine a focus state at each of a plurality of focus detection zones, for example multi-points e 1  through e 15 . In an embodiment, the multi-points e 1  through e 15  are arranged symmetrically in all directions at the center of a photograph screen as illustrated in  FIG. 3A . A multi-point e 8  from among the 15 multi-points e 1  through e 15  is referred to as a central multi-point. According to a setting criterion of the multi-AF region, two central upper and lower regions or two central right and left regions, such as the multi-points e 8  and e 3  or the multi-points e 8  and e 9 , may be defined as the central multi-point. 
       FIG. 3B  illustrates an example in which subjects exist within the multi-AF region illustrated in  FIG. 3A . 
     In  FIG. 3B , a flower  310  is located at a position nearest to a photographer, and a person  320  and a mountain  330  are sequentially located behind the flower  310 . Referring to  FIGS. 3A and 3B , the flower  310  is located in the multi-point e 12 , the person  320  is located in the multi-point e 8 , and the mountain  330  ranges over the multi-points e 4 , e 5 , e 9 , and e 10 . 
     In a digital photographing apparatus based on a contrast AF method, photographing is performed with priority only on a subject at close range. Referring to  FIG. 3B , the flower  310  is closest to the photographer, and thus the multi-point e 12  is brought into focus. 
     However, if the person  320  is intended as a main subject of the image of  FIG. 3B , photographing needs to be performed with priority on the central subject in the multi-point e 8 . Thus, even when the contrast AF method is used, a multi-AF method which selectively focuses on the nearest subject or on the central subject by measuring distances at multi-points is needed. 
       FIGS. 4A and 4B  illustrate a multi-AF region, namely, an example of a focus detection region in which focus detection is performed during moving picture photographing.  FIG. 5  illustrates an exemplary multi-AF region in which regions (multi-points e 19 , e 20 , and e 21 ) partially overlap one another. 
     In an embodiment, three multi-points e 16 , e 17 , and e 18  are arranged symmetrically as a multi-AF region about the center of a photograph screen as illustrated in  FIG. 4A . 
       FIG. 4B  illustrates an example in which subjects exist in the multi-AF region illustrated in  FIG. 4A . In  FIG. 4B , a flower  410  is located at a position closest to a photographer, and a person  420  and a mountain  430  are sequentially located behind the flower  410 . 
     As in  FIGS. 3A and 3B , in this case, when a digital photographing apparatus uses an existing contrast AF method, a subject closest to a photographer is selected as the AF target. Thus, the flower  410 , that is, the multi-point e 16 , of  FIG. 4B  is brought into focus. 
     Therefore, a digital photographing apparatus using an existing contrast AF method needs to apply a new multi-AF function further providing central point priority along with nearest point priority to focus on the person  420 , that is, the multi-point e 17 . 
       FIG. 6  illustrates a table for explaining a near and central mixed focus selection method conventionally used in a phase difference AF method. In the phase difference AF method, the focus lens  104  is adjusted to focus on the nearest subject or the central subject according to magnification. 
     In the phase difference AF method, the focus lens  104  is in a pause state, and thus a defocus amount may be previously detected. On the other hand, in the contrast AF method, the position of the focus lens  104  may only be detected by adjusting the focus lens  104 . Thus, a method different from the phase difference AF method is required for the contrast AF method to be able to use the central multi-point focus selection method along with the nearest multi-point focus selection method. 
       FIGS. 7A and 7B  illustrate an exemplary multi-AF method that adaptively uses the nearest multi-point focus selection method or the central multi-point focus selection method. 
     Referring to  FIGS. 7A and 7B , the multi-AF method may be divided into two types according to patterns of distances between subjects existing in the multi-AF region.  FIG. 7A  illustrates application of the multi-AF method in a case where a subject located in a central multi-point of the multi-AF region is the farthest from a photographer.  FIG. 7B  illustrates application of the multi-AF methods in cases other than the case of  FIG. 7A . 
     In  FIGS. 7A and 7B , β denotes an image magnification of the subject. The image magnification is a function between a focal distance of the zoom lens  102  and a subject distance, and is defined as a ratio of the size of the subject to the size of the image captured at the imaging device  204 . The focal distance of the zoom lens  102  and the position of the focus lens  104  may be ascertained from the output values of the zoom lens position detecting sensor  103  and the focus lens position detecting sensor  106 , respectively. 
     In the graphs of  FIGS. 7A and 7B , β m  on the x axis indicates an image magnification of a center region. The center region denotes a central multi-point of the 15 multi-points illustrated in  FIGS. 3A and 3B . In the graphs of  FIGS. 7A and 7B , β near  on the y axis indicates an image magnification of a subject nearest to a photographer. The image magnification increases the closer to the origin. The image magnification decreases the farther from the origin. 
     β near  may include β m , but β m  may not include β near . Thus, there is no case where a subject is selected, as indicated in  FIGS. 7A and 7B  by a region  710  above a region where β m =β near . 
     As in the embodiment of  FIG. 7A , if the central multi-point is the farthest point from a photographer by measuring distances at multi-points, it is determined whether β near  is equal to or greater than a magnification of 1/15. If β near  is greater than the magnification of 1/15, current photographing is determined to be macro photographing, and the focus is adjusted on the central multi-point. On the other hand, if β near  is less than the magnification of 1/15, the focus is adjusted on the nearest multi-point by measuring distances at multi-points. 
     As in the embodiment of  FIG. 7B , in the cases other than the case where the central multi-point is the farthest from the photographer, both the nearest multi-point focus selection method and the central multi-point focus selection method may be used as follows. 
     When β near  is greater than the magnification of 1/15, the photographing is determined to be macro photographing, and thus the focus is adjusted on the central multi-point. 
     When β near  is less than the magnification of 1/15, two types of selections may be made. 
     First, when β m  is less than the magnification of 1/15 and greater than a magnification of 1/60, the focus is adjusted on the central multi-point. Next, when β m  is less than the magnification of 1/60, the focus is adjusted on the nearest multi-point in which the subject is the closest from a photographer by measuring distances at multi-points. 
       FIG. 3B  corresponds to the case of  FIG. 7B , where the center multi-point is not farthest from the subject. Thus, when β near  is greater than the magnification of 1/15, the focus is adjusted on the central multi-point e 8  of  FIG. 3B . Even when β m  is less than the magnification of 1/15 and greater than the magnification of 1/60, the focus is adjusted on the central multi-point e 8 . When β m  is less than the magnification of 1/60, the focus is adjusted on the multi-point e 12  where the subject nearest to the photographer exists. 
       FIGS. 7A and 7B  illustrate ratios 1/15 and 1/60, which are set as bases for selecting the central multi-point and the nearest multi-point in the case where a digital photographing apparatus is used horizontally to perform photographing. Thus, in a case where a digital photographing apparatus is used vertically to perform photographing, the bases for selecting the central multi-point and the nearest multi-point may be different from the ratios 1/15 and 1/60. In a case where two central multi-points are selected, a magnification β u  of a region directly over the central multi-point may be further used during macro photographing. 
     The magnifications 1/15 and 1/60 when the multi-AF method of  FIGS. 7A and 7B  is implemented in the contrast AF are only an embodiment, and may be changed or replaced by other magnifications by one of ordinary skill in the art to which the present embodiment pertains. Also, the magnifications 1/15 and 1/60 may be changed in a method of magnifying a central multi-point, or the base for selecting the central multi-point and the nearest multi-point may be more finely divided than the magnification 1/15 so that the central multi-point and the nearest multi-point may be selected together. A method of applying a multi-AF method using the contrast AF, according to an embodiment, will be described later with reference to  FIGS. 12 through 22 . 
       FIG. 8  is an exemplary graph for describing detection of a peak value of AF evaluation values in a contrast AF method.  FIG. 8  shows the relationship between the AF evaluation value and the position of the focus lens in the contrast AF method. In  FIG. 8 , the horizontal axis indicates lens synchronization positions (focusing positions corresponding to intermediate points of time of AF detection), and the vertical axis indicates the AF evaluation values. The AF evaluation values and focusing positions corresponding to the AF evaluation values are stored in the lens memory  112 . 
     In the contrast AF method, a lens synchronization position LV pk    820  corresponding to a peak value V pk    810  of the AF evaluation values is detected in order to find a region on which the focus lens  104  is to be focused. 
     In  FIG. 8 , the actual peak position of the lens is LV pk    820  where the evaluation value takes a maximum value V pk    810 . The AF evaluation values, however, are discrete, and thus an actual peak value may be calculated by interpolating the AF evaluation values. The interpolation for detecting the peak value V pk    810  may be performed using lens synchronization positions LV 3 , LV 4 , and LV 5  and three data, namely, AF evaluation values L(s 3 ), L(s 4 ), and L(s 5 ) corresponding to the lens synchronization positions LV 3 , LV 4 , and LV 5 . 
     Central points of charge accumulation periods of the AF evaluation values, namely, detection central positions LV 1 , LV 2 , LV 3 , etc., are set to be lens synchronization positions. Information about the lens synchronization positions may be obtained from the lens  100  of  FIG. 1 . The information about the lens synchronization positions stored in the lens  100  may be ascertained at the timing corresponding to the lens synchronization positions LV 1 , LV 2 , LV 3 , etc. 
     The focus lens  104  may be moved to an in-focus position by detecting the positions of the lens at the timings synchronized with the detection central positions. 
       FIG. 9  illustrates an example of a method of determining a range of potential peak (hereinafter, RPP). The RPP denotes a range where it is determined whether there is a possibility that a peak of AF evaluation values exists. 
       FIG. 9  illustrates a method of detecting AF evaluation values before a contrast peak value is found. The AF evaluation values corresponding to the lens synchronization positions LV 1 , LV 2 , and LV 3  are referred to as s 1 , s 2 , s 3 , respectively. In an embodiment, when an AF evaluation value monotonically increases or decreases, it is determined that a contrast peak exists on the side where the AF evaluation value monotonically increases or decreases. 
     For example, as illustrated in  FIG. 9 , when s 1 &lt;s 2 &lt;s 3 , it is determined that a peak value exists on the right side (scanning direction) of the lens synchronization position LV 3 . This process is referred to as range detection of potential peak. On the other hand, when s 1 &gt;s 2 &gt;s 3 , it is determined that a peak value exists on the left side (direction opposite to the scanning direction) of the lens synchronization position LV 1 . In this case, the scanning direction may be inverted for range detection. In addition, as the frequency of AF detection for acquiring an AF evaluation value decreases, a RPP may be detected from a point far away from a peak. In general, a RPP may be detected starting from a point several tens of Fδ before a peak. Here, F indicates a photographing iris value, and δ indicates a permissible circle of uncertainty. 
       FIGS. 12 through 22  illustrate applications of the multi-AF method illustrated in  FIG. 7  in the contrast AF method, according to embodiments of the present invention. 
     In  FIGS. 12 through 22 , the x axis indicates a lens synchronization position, the y axis indicates an AF evaluation value,   indicates a position where scanning starts, and ∘ indicates an in-focus position. 
     Although AF evaluation values can be acquired from the 15 multi-points of  FIG. 3 , respectively,  FIGS. 12 through 22  display only AF evaluation values for some of the 15 multi-points. In  FIGS. 12 through 22 , M denotes a peak value of a subject in a central multi-point, N 0  denotes a peak value of a nearest subject in a nearest multi-point, N 1  denotes a peak value of a first near subject, and F denotes a peak value of a subject relatively far from a photographer from among subjects other than the above-described subjects. Also, N z  and ∞z denote range detection points where it is determined whether peaks can exist after the point N z  and before the point ∞z. N z  and ∞z are also used to find out a RPP. The point N z  denotes a range detection point in a Near direction, and the point ∞z denotes a range detection point in a ∞ direction. Refer to  FIGS. 8 and 9 , the Near direction represents the leftward direction along the horizontal axis, and the ∞ direction represents the rightward direction along the horizontal axis. 
       FIGS. 12 through 19  illustrate an example of performing scanning in a direction from ∞ to Near.  FIGS. 20 through 22  illustrate an example of performing scanning in a direction from Near to ∞. 
       FIG. 12  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a central multi-point and a near region are both detected, according to an embodiment. The near region may be associated with the nearest multi-point. 
     A case A 1  where a lens is located at a point -∞, a case A 2  where the lens is located in a ∞ direction from a peak M  1240  of the central multi-point, and a case A 3  where the lens is located in a Near direction from the peak M  1240  of the central multi-point are described as follows. 
     In the case A 1 , namely, a case  1210 , the lens performs scanning from the point ∞ to a point N z    1260 , which is the range detection point. Since the AF evaluation value of the subject, which is the peak value N 0 , monotonically decreases after the point N z    1260 , no peaks exist beyond N z . Thus, scanning is not performed until a nearest point  1270 , and the travelling direction of the focus lens is inverted at the point N z    1260 . 
     In the case A 1 , while the lens is scanning from the point ∞  1210  to the range detection point N z    1260 , the lens passes through the peak M of the central multi-point and the peak N 0  of the nearest multi-point. Thereafter, by applying the multi-AF method at the range detection point N z    1260 , the lens is driven to be focused on the peak M or N 0 . The multi-AF method refers to  FIGS. 7A and 7B . However, the multi-AF method of  FIGS. 7A and 7B  is only an example, and various changes may be made therein. 
     Also, in a case A 2 , while the lens is scanning from a current position  1220  to the range detection point N z    1260 , the peak M of the central multi-point and the peak N 0  of the nearest multi-point are both ascertained. Thereafter, by applying the multi-AF method at the range detection point N z    1260 , the lens is driven to be focused on the peak M or N 0 . 
     In a case A 3 , when the lens scans from a current position  1230  to the range detection point N z    1260 , only the peak N 0  in the nearest multi-point is detected, that is, the peak M in the central multi-point is not detected. Thus, the scanning direction is inverted to the ∞ direction, and if the peak M in the central multi-point is detected during the scanning in the ∞ direction, the scanning is stopped. Thereafter, the scanning direction is changed at the PK M  point  1240 , and the lens is driven to be focused on the peak M or N 0  by applying the multi-AF method. 
       FIG. 13  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the central multi-point M is not detected because its contrast is low, according to an embodiment. 
     In a case B 1  ( 1310 ), the lens is moved from the ∞ point  1390  to a range detection point N z    1360 . Since it is determined that no subjects exist in a central multi-point, the lens is driven at the N z  point  1360  and focused on a peak N 0  of a nearest subject. 
     In a case B 2  ( 1320 ), since the lens is moved from a point  1320  located between the ∞z point and Nz, if it is determined up to the range detection point N z    1360  that no subjects exist in the central multi-point, the direction of scanning is inverted at the N z  point  1360  and scanning is performed up to the ∞z point  1380  to search for the subject in the central region. Since it is determined according to the scanning that no subjects exist in the central multi-point, the lens is focused on the nearest subject N 0 . 
       FIG. 14  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a subject exists at a location (e.g., an ultra-near region) nearer to a digital photographing apparatus than a nearest location detectable by the digital photographing apparatus and when a magnification of the central multi-point M is greater than 1/60, according to an embodiment.  FIG. 14  shows the AF value of the subject corresponding to N n . In many cases, the ultra-near region denotes a case where the subject exists within a photographing distance. 
     A case C 1  where a lens is initially located at a point ∞, a case C 2  where the lens is initially located between the ∞ point and a PK M  point  1440  corresponding to a peak M of the central multi-point, and a case C 3  where the lens is initially located between the PK M  point  1440  and a point NEAR will now be described. 
     In the case C 1  ( 1410 ), scanning is performed from the point ∞ to a range detection point N z    1460 . Since a RPP is detected at the range detection point N z    1460 , the scanning continues up to a final end  1470 . Since a graph including the peak N n  monotonically increases at the range detection point N z    1460 , it is determined that a new peak exists on the right side of the range detection point N z    1460  (in a scanning direction). After up to the final end  1470  is scanned, the lens is focused on the peak M or N 0  by applying the multi-AF method. The application of the multi-AF method refers to  FIGS. 7A and 7B . 
     In the case C 2  ( 1420 ), after an operation similar to the operation in the case C 1  is performed, the lens is focused on the peak M or N 0  by applying the multi-AF method. 
     In the case C 3  ( 1430 ), since a central multi-point is not detected even when up to the final end  1470  is scanned, the direction of scanning is inverted at the final end  1470  and is performed to detect the peak M of the central multi-point. After the peak M of the central multi-point is detected, the direction of scanning is inverted, and the lens is focused on the peak M or N 0 . 
       FIG. 15  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the central multi-point M fails to be detected and a subject existing in the near region is nearer to a photographer than the nearest location detectable by the digital photographing apparatus, according to an embodiment; 
     In a case D 1  ( 1510 ), scanning is performed from a point ∞ to a range detection point N z    1560 . Since a RPP region is detected at the range detection point N z    1560 , up to a final end  1570  is scanned. Since the central multi-point is not detected because its contrast is low, the lens is focused on a peak N 0  of the near region. 
     In a case D 2  ( 1520 ), after scanning is performed up to the final end  1570 , the direction of scanning is inverted and continues up to the range detection point ∞z. Then, the direction of scanning is inverted again, and the lens is focused on the peak N 0 . 
       FIG. 16  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the magnification of a subject in the central multi-point M is less than 1/60, according to an embodiment. When the magnification of the subject in the central multi-point M is less than 1/60, the lens is always focused on a near region when referring to  FIGS. 7A and 7B . Thus, in cases E 1  ( 1610 ) and E 2  ( 1620 ), immediately after scanning is performed, the lens is focused on a peak N 0 . In a case E 3  ( 1630 ), after up to a range detection point N z    1660  is scanned, the direction of scanning is inverted and continues until the point 1/60. If a central multi-point is not detected during the scanning up to the point 1/60, the lens is focused on the peak N 0 . In this case, a region less than the point 1/60 does not need to be scanned. 
       FIG. 17  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the central multi-point M is not detected because its contrast is low, and when a range detection point ∞z is closer to ∞ than the point 1/60  1751  is, according to an embodiment. 
     In a case F 1  ( 1710 ), after up to a range detection point N z    1760  is scanned, the direction of scanning is inverted, and the lens is focused on a peak N 0 . In a case F 2  ( 1720 ), after up to the range detection point N z    1760  is scanned, the direction of scanning is inverted and continues up to a point 1/60  1751 . Although a central multi-point is detected in a position range lower than the point 1/60  1751 , the lens is focused on a near region when the multi-AF method is used (see  FIGS. 7A and 7B ). Thus, only up to the point 1/60  1751  is scanned, the direction of scanning is inverted, and the lens is focused on the peak N 0 . 
       FIG. 18  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when a subject in the central multi-point is detected at a location ∞ and a point 1/60  1851  is closer to ∞ than a range detection point ∞z  1880  is, according to an embodiment. 
     In a case G 1  ( 1810 ), after scanning is performed from a ∞ point to a range detection point N z    1860 , the direction of scanning is inverted, and the lens is focused on a peak N 0 . This is because the central multi-point M has been detected during the scanning from the ∞ point to the range detection point ∞z. 
     In a case G 2  ( 1820 ), after scanning is performed up to the range detection point Nz  1860 , the direction of scanning is inverted and continues. Thereafter, a RPP is detected at a range detection point ∞z  1880 , and thus the scanning is performed toward the ∞ point and continues up to the point 1/60. Since a central multi-point is not detected even when up to the point 1/60 is scanned, the direction of scanning is inverted again, and the lens is focused on the peak N 0 . In this case, due to a determination that a difference in an AF time between the range detection point ∞z  1880  and the point 1/60  1851  is little, the inversion of the scanning direction may be omitted. 
       FIG. 19  illustrates application of the multi-AF method illustrated in  FIG. 7  in the contrast AF method when all subjects exist at the location ∞, according to an embodiment. 
     In a case H 1  ( 1910 ), the focus lens is moved in a Near direction from the ∞ point to a range detection point N z    1960 , then the travelling direction of the focus lens is inverted in a ∞ direction. Since a RPP is detected at a range detection point ∞  1950 , the scanning continues in the ∞ direction. Since neither a peak of a near region nor a peak of a central multi-point is detected until a point 1/60  1951 , the direction of scanning is inverted at a final end  1910  and continues on up to the ∞ point  1990 . Then, the lens is focused on a peak N 0  existing on the ∞ point  1990 . 
     In a case H 2  ( 1920 ), after scanning is performed up to the range detection point N z    1960 , the moving direction of the focus lens is inverted and scanning is performed in a ∞ direction. Similar to the case H 1 , since neither a peak of a near region nor a peak of a central multi-point is detected until the point 1/60  1951 , the scanning is performed up to the ∞ point  1990 , and then the direction of scanning is inverted at the final end, and the lens is focused on the peak N 0    1990 . 
       FIGS. 20 through 22  illustrate application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when scanning is performed from a NEAR point to a ∞ point. 
       FIG. 20  illustrates an embodiment in which a magnification of a central multi-point is greater than 1/60. In a case A 1  ( 2010 ), a start point of scanning is located closer to the ∞ point than a peak M of a central multi-point is, and is also located at a point less than the point 1/60. In a case A 2  ( 2020 ), a start point of scanning is located closer to the ∞ point than the peak M of the central multi-point is, and is also located at a point greater than the point 1/60. In a case A 3  ( 2030 ), a start point of scanning is located between the peak M of the central multi-point and the NEAR point. 
     In the cases A 1  ( 2010 ) and A 2  ( 2020 ), since a RPP is not detected at a range detection point ∞z  2080 , the travelling direction of the focus lens is inverted at the range detection point ∞z  2080  and scanning is performed in the Near direction until a point N z    2060 . Thereafter, the lens is focused on the peak M by applying the multi-AF method. 
     In a case A 3  ( 2030 ), scanning is performed in the ∞ direction, and when the peak M is detected, the moving direction of the focus lens is inverted and scanning is performed in a Near direction until the point N z    2060 . Thereafter, the direction of scanning is inverted again at the point N z    2060 , and the lens is focused on the peak M or N 0 . 
       FIG. 21  illustrates application of the multi-AF method illustrated in  FIGS. 7A and 7B  in the contrast AF method when the contrast of the central multi-point cannot be detected, according to an embodiment. 
     In a case B 1  ( 2110 ), a start point of scanning is located between range detection points N z  and ∞z. In a case B 2  ( 2120 ), a start point of scanning is located between the range detection point N z  and the NEAR point. 
     In the case B 1  ( 2110 ), since a RPP is not detected at the range detection point ∞z  2180 , the direction of scanning is inverted at the range detection point ∞z  2180 , toward a Near direction until the range detection point N z    2160 . Thereafter, the lens is focused on a peak N 0 . In the case B 2  ( 2120 ), the direction of scanning is inverted at the range detection point ∞z  2180 , and the lens is focused on the peak N 0 . 
       FIG. 22  illustrates an embodiment in which a subject in a near multi-point exists at an ultra-near location nearer to the photographer than the nearest location detectable by the digital photographing apparatus and a subject in a central multi-point exists at the location ∞. Here, N n  denotes a subject existing closer to a final end than a near subject N 0  is. 
     In a case C 1  ( 2210 ), a start point of scanning is located between range detection points ∞z  2280  and N z    2260 . In a case C 2  ( 2220 ), a start point of scanning is a final end  2270 . 
     In the case C 1  ( 2210 ), since a RPP is detected at the range detection point ∞z  2280 , the scanning is performed up to a ∞ point  2290  and then the direction of scanning is inverted at a final end just beyond the ∞ point  2290 . Thereafter, a RPP is also detected at the range detection point N z    2260 , and thus the scanning is performed up to a final end  2270 . Then, the lens is focused on the near subject N 0 . 
     In a case C 2  ( 2220 ), since a RPP is detected at the range detection point ∞z  2280 , the focus lens is moved up to the ∞ point  2290 , and the direction is inverted at the final end just beyond the ∞ point  2290 . Thereafter, the lens is focused on the near subject N 0 . 
     Due to the scanning operations illustrated in  FIGS. 12 through 22 , the multi-AF method may be implemented at high speed in the contrast AF. 
     EMBODIMENT 1 
       FIGS. 23 through 26  are flowcharts of an operation of the digital photographing apparatus  1  of  FIG. 1 . 
       FIG. 23  is a flowchart of a driving process (operation A 1 ) of the digital photographing apparatus  1 , according to an embodiment. In operation S 2310 , when the main switch SM of the digital photographing apparatus  1  is turned on, the mode of the digital photographing apparatus  1  is set by the manipulation unit  207  or the like. Then, lens information is required as an input to the lens  100  in order to operate the digital photographing apparatus  1  in operation S 2320 . The lens information corresponds to unique lens parameters stored in the lens memory  112  of  FIG. 1 , and is necessary for AF, AE, AWB, image quality control, etc. 
     In operation S 2330 , the imaging device  204  of  FIG. 2  periodically starts photographing. Then, AE and AWB values are calculated in operation S 2340 , and a live view is displayed in operation S 2350 . Although the operations S 2310  through S 2350  are sequentially illustrated, all of the operations S 2310  through S 2350  may be performed at the same time while image information is being input from the imaging device  204 . 
     In operation S 2360 , it is determined whether the main switch SM of the digital photographing apparatus  1  has been turned off. If the main switch SM of the digital photographing apparatus  1  has not been turned off, the method is fed back to operation S 2310 , and a live view display is repeated. On the other hand, if the main switch SM of the digital photographing apparatus  1  has been turned off, operation A 1  of the digital photographing apparatus  1  is paused, in operation S 2370 . 
       FIGS. 24A and 24B  are flowcharts of an operation (A 2 ) of AF detection in the digital photographing apparatus  1  when the shutter release button is half-pressed (operation S 1  is performed) in the live view display operation S 2350  of  FIG. 23 , according to an embodiment. 
     When an interrupt signal of the half-pressing operation S 1  is applied in operation S 2401 , the focus lens  104  is fast driven in a Near direction, in operation S 2402 . The lens control unit  110  drives the lens  100  at a constant speed in order to achieve contrast AF. When the half-pressing operation S 1  has been performed, the driving of the focus lens  104  in the Near direction may decrease an AF time during which the multi-AF method is used. However, various changes in the driving of the focus lens  104  may be made. In the present embodiment, during moving picture photographing, scanning may be begun by preferentially performing infinite direction scanning. In more detail, the embodiment as illustrated in  FIGS. 20 through 22  may be performed so as to drive the focus lens  104  in an infinite direction. 
     Thereafter, in operation S 2403 , a photographing timing signal is input. The photographing timing signal represents the timing when AF detection is initiated. The photographing timing signal is generated to correspond to a set AF detection region. The CPU  224  counts driving signals that are generated in the imaging device control unit  205 . When a predetermined number of driving signals are counted, this time is determined as the timing when AF detection is to be initiated. 
     When the photographing timing signal is input, the imaging device  204  inputs an image signal of an AF region to an AF detection circuit of the pre-processor  220  of the camera control unit  209  and performs AF detection, in operation S 2404 . The AF detection enables the AF evaluation values L 1  through L 15  (corresponding to el through e 15  of  FIG. 3A ) of a multi-divided region to be calculated. In this case, the multi-divided region, namely, a focus detection region, is the same as that illustrated in  FIGS. 3A and 3B . The focus detection region is divided into 15 regions e 1  through e 15  of  FIG. 3A . In operation S 2405 , the AF evaluation values L 1  through L 15  are calculated from the multi-divided region. In other words, the AF evaluation values L 1  through L 15  may be obtained from the 15 regions e 1  through e 15 , respectively. 
     After the AF evaluation values are calculated, a current focal distance, a position of the focus lens  104  at the AF detection timing, and conversion coefficient KL values corresponding to the conversion coefficients of the focus lens driving amount and the focus deviation amount of a photographing lens are input to the lens  100 , in operation S 2406 . The KL values are stored together with the AF evaluation values by making sets. 
     Thereafter, in operation S 2407 , it is determined whether the lens has reached the range detection point N z . When the lens has reached the range detection point N z  at least once, the method proceeds to operation S 2408 . The case where the lens has reached the range detection point N z  at least once includes both a case where the lens has reached the range detection point N z  while moving from the infinite direction to the Near direction and a case where the lens is inversely driven from the Near direction to the infinite direction after the lens has reached the point N z . 
     When a subject in a central multi-point and a subject in a nearest multi-point, which is closest to a photographer, are both detected in operation S 2408 , or when the subject in the region nearest to the photographer is not detected but the subject in the central multi-point is detected in operation S 2409 , operation S 2414  (see  FIG. 24B ) in an AF process A 21  is performed. When the subject in the region nearest to the photographer is not detected but the subject in the central multi-point is detected in operation S 2409 , the subject in the central multi-point may be considered as a subject nearest to the photographer. 
     In operation S 2410 , it is determined whether the current position of the focus lens  104  is less than the point 1/60. If the current position of the focus lens  104  is less than the point 1/60, it is determined whether at least one peak region has been detected, in operation S 2413 . If at least one peak region has been detected, the AF process A 21  is conducted. Otherwise, a process A 22  (see  FIG. 24B ) is conducted. 
     On the other hand, if the current position of the focus lens  104  is not less than the point 1/60, an end determination process S 2411  is performed, which will be described later with reference to  FIG. 25 . Thereafter, in operation S 2412 , it is determined whether the current position of the focus lens  104  has reached a range detection point ∞z for an infinite direction. If the current position of the focus lens  104  has not reached the range detection point ∞z, the method is fed back to operation S 2403  in order to continuously perform scanning, and a photographing timing signal is input. 
     On the other hand, if the current position of the focus lens  104  has reached the range detection point ∞z, it is determined whether at least one peak has been detected, in operation S 2413 . In more detail, while the moving direction of the focus lens is inverted after scanning up to the nearest multi-point and the scanning is being performed up to the point 1/60, if at least the nearest subject is detected, the AF process A 21  (including operations S 2414  through S 2420 ) is conducted. On the other hand, if no peaks are detected, a process A 22  (including operations S 2421  and S 2422 ) is conducted. 
     The AF process A 21  (including operations S 2414  through S 2420 ) will now be described in detail with reference to  FIG. 24B . If at least one peak is detected in operation S 2413 , first, a main subject is selected using the multi-AF method, in operation S 2414 . Thereafter, in operation S 2415 , an AF evaluation value is modified to calculate the peak value Vpk and the lens synchronization position value LVpk. In operation S 2416 , it is determined whether the peak value Vpk of the AF evaluation value is greater than a preset lens synchronization position value PKT. If the peak value Vpk is greater than the preset lens synchronization position value PKT, a peak error due to the position of an AF detection region is corrected, in operation S 2417 . The peak error is referred to as ΔIB, and denotes an error due to a difference between the frequency of performing the AF detection by the photographing lens and the frequency of actual AF detection. A peak error correction value that is changed by the focus detection region is referred to as ΔIBoff. Thus, in operation S 2417 , the peak error correction value ΔIBoff obtained by the correction of the position of the AF detection region is corrected. In general, in operation S 2417 , a defocus amount is expressed in units of μm. Thereafter, in operation S 2418 , the driving amount of the focus lens  104  is determined by multiplying the conversion coefficient KL of the focus lens driving amount of the photographing lens by the conversion coefficient KL of the focus deviation amount of the photographing lens ΔLVpk. The conversion coefficients KL used in operation S 2418  are conversion coefficients KL that are closest to the lens synchronization position value LVpk. 
     Then, in operation S 2419 , the camera control unit  209  transmits, to the lens control unit  110 , the driving amount of the focus lens  104 , a command to drive the focus lens  104  in an inverse direction, and a command to drive the focus lens  104  at high speed at a target position, which is ascertained in operation S 2418 . In operation S 2419 , the lens drives the focus lens  104  to the target position by initiating inverse direction driving, so that the lens is brought into focus. In operation S 2420 , a focus display is performed for a predetermined period of time, and then the AF process A 21  is concluded. Thereafter, the method is fed back to operation A 1  of the digital photographing apparatus  1  illustrated in  FIG. 23 , and thus a live view display is performed. 
     The process A 22  (including the operations S 2421  and S 2422 ) will now be described in greater detail with reference to  FIG. 24B . In operation S 2421 , a command to stop driving the focus lens  104  is issued according to a determination that the contrast of a subject is low. Then, in operation S 2422 , NG (meaning “no good”, i.e, fail) is displayed. Then, the method is fed back to operation A 1  of the digital photographing apparatus  1  illustrated in  FIG. 23 , and thus a live view image is displayed. 
       FIG. 25  is a flowchart of the end determination process S 2411  included in the operation of the digital photographing apparatus  1  illustrated in  FIG. 24A , according to an embodiment. 
     First, in operation S 2510 , it is determined whether the focus lens  104  is located within a RPP. The RPP denotes a region where it is determined whether there is a possibility that a peak exists. Further, N z  and ∞z denote range detection points where it is determined whether peaks can exist after the point N z  and before the point ∞z. Thus, N z  and ∞z are used to determined a RPP. The point N z  denotes a range detection point near the NEAR point, and the point ∞z denotes a range detection point near the ∞ point. 
     If it is determined in operation S 2510  that the focus lens  104  is located within the RPP, it is determined whether a peak exists, in operation S 2520 . The determination as to whether a peak exists refers to  FIG. 9 . If a peak exists, the focus lens  104  is moved up to the end of the scan range, in operation S 2530 . On the other hand, if no peaks exist, the focus lens  104  is driven in an inverse direction by changing the direction of the scanning, in operation S 2540 . In this case, if the focus lens has not moved up to the end of the scan range, the moving direction of the focus lens  104  is inverted immediately. If it is determined in operation S 2510  that the focus lens  104  is outside the RPP, the focus lens is also returned. 
       FIGS. 26A ,  26 B, and  26 C are flowcharts of an operation of the digital photographing apparatus when the shutter release button is fully pressed (the full-pressing operation S 2  is perfomed), according to an embodiment. After the AF operation A 2  is completed with the half-pressing operation S 1  performed in  FIG. 24A , the full-pressing operation S 2  is performed, and an operation A 3  starts. In operation S 2601 , it is determined whether a photographing mode is a moving picture mode. 
     If the photographing mode is not determined to be a moving picture mode in operation S 2601  and the lens is in-focus in operation S 2602 , a still picture is captured and then a captured image is displayed for a predetermined period of time, in operations S 2603  and S 2604 . Thereafter, the method is fed back to operation A 1  illustrated in  FIG. 23  to perform live view display. 
     If the photographing mode is determined to be a moving picture mode in operation S 2601 , a moving picture starts being captured, in operation S 2605 . Then, when the shutter release button is fully pressed (S 2 ) again, the capturing is paused. Then, in operation S 2606 , it is determined whether the lens is in-focus. If it is determined in the operation S 2606  that the lens  100  is in-focus, it is determined whether a predetermined period of time Tw has lapsed, in operation S 2607 . In the moving picture mode, since a continuous AF is performed, AF is gradually performed during the predetermined period of time Tw in order to bring the lens into focus. If it is determined in operation S 2606  that the lens is focused, the predetermined period of time Tw lapses in operation S 2607 , and then the focus lens is driven at low speed in the Near direction, in operation S 2608 . The predetermined period of time Tw may be set to be about 500 ms to about 1 s. On the other hand, if it is determined in operation S 2606  that the lens is out of focus, the focus lens is driven at low speed in the Near direction in operation S 2608  without passing through operation S 2607 . In order to drive the focus lens at low speed in the Near direction, a command to drive the focus lens at low speed in the Near direction is transmitted to the lens  100 . Since the lens control unit  110  of  FIG. 1  performs continuous AF, the lens control unit  110  drives the lens at a lower speed than when performing general AF. 
     Thereafter, a multi-divided focus detection region, for example a multi-AF region illustrated  FIG. 3A  , is changed in accordance with the moving picture mode, for example a multi-AF region illustrated  FIG. 4A , in operation S 2609  illustrated in  FIG. 25B . In the moving picture mode, the multi-divided focus detection region is divided into larger regions. For example, in a half-pressing operation S 1 , a multi-divided focus detection region as in  FIG. 3A  is used. In the moving picture mode, a multi-divided focus detection region as in  FIG. 4A  is used. 
     Referring to  FIG. 26B , in operation S 2610 , a photographing timing signal is input according to the changed multi-divided focus detection region. The photographing timing signal denotes a timing signal that initiates AF detection and is generated for a position of a focus detection region. Thus, a photographing timing signal suitable for a change made in the multi-divided focus detection region according to the moving picture mode is generated. The photographing timing signal may be generated through a process in which the CPU  224  counts driving signals generated in the imaging device control unit  205  of  FIG. 2 . 
     When the photographing timing signal is input in operation S 2610 , an AF detection circuit in the pre-processor  220  of  FIG. 2  detects AF, in operation S 2611 . In operation S 2612 , the AF evaluation values L 16 , L 17 , and L 18  of focus detection regions corresponding to the regions e 16 , e 17 , and e 18  of  FIG. 4A  are calculated. 
     Thereafter, in operation S 2613 , the lens  100  inputs a current focal distance, a position of the focus lens  104  at the AF detection timing, and KL values corresponding to the conversion coefficients of the focus lens driving amount and the focus deviation amount of a photographing lens. The KL values are stored together with their corresponding AF evaluation values. 
     In operation S 2614  and its subsequent operations, scanning is performed to apply the multi-AF method. When a peak of each focus detection region is obtained, a main subject is selected according to the multi-AF method, in operation S 2631  illustrated in  FIG. 26C . The multi-AF method refers to  FIG. 31 . In the moving picture mode, the multi-divided focus detection region of  FIG. 4A  may be used. 
     First, in operation S 2614 , it is determined whether the lens has reached the range detection point N z . When the lens has reached the range detection point N z  at least once, the method proceeds to operation S 2615 . The case where the lens has reached the range detection point N z  at least once includes both a case where the lens has reached the range detection point N z  while moving from the infinite direction to the Near direction and a case where the lens is inversely driven from the Near direction to the infinite direction after the lens has reached the point N z . 
     When a subject in a central multi-point and a subject in a region nearest to a photographer are both detected in operation S 2615 , or when the subject in the region nearest to the photographer is not detected but the subject in the central multi-point is detected in operation S 2616 , operation S 2631  (see  FIG. 26C ) in a process A 32  is performed. When both subjects in the region nearest to the photographer and in the central multi-point are not detected in operation S 2615  and the subject in the central multi-point is not detected in operation S 2616 , it is determined whether the current position of the focus lens  104  is less than the point 1/60, in operation S 2617 . 
     If the current position of the focus lens  104  is less than the point 1/60, it is determined whether at least one peak region has been detected, in operation S 2620 . If at least one peak region has been detected, the process A 32  is conducted. Otherwise, a process A 33  is conducted. 
     On the other hand, if the current position of the focus lens is not less than the point 1/60, an end determination process S 2618  is performed. The end determination process S 2618  refers to  FIG. 25 . Thereafter, in operation S 2619 , it is determined whether the current position of the focus lens  104  has reached a range detection point ∞z for an infinite direction. If the current position of the focus lens  104  has not reached the range detection point ∞z, the method is fed back to operation S 2609  in order to continuously perform scanning, and a photographing timing signal is input. 
     On the other hand, if the current position of the focus lens has reached the range detection point ∞z, it is determined whether at least one peak has been detected, in operation S 2620 . In more detail, while the moving direction of the focus lens is changed after scanning up to the nearest multi-point and the scanning is being performed up to the point 1/60, if at least the nearest subject is detected, the process A 32  is conducted. On the other hand, if no peaks are detected, the process A 33  is conducted. 
     If at least one peak is detected in operation S 2620 , first, a main subject is selected using the multi-AF method, in operation S 2631 . Thereafter, in operation S 2632 , an AF evaluation value is modified to calculate the peak value Vpk and the lens synchronization position value LVpk. In operation S 2633 , it is determined whether the peak value Vpk of the AF evaluation value is greater than a preset lens synchronization position value PKT. If the peak value Vpk is greater than the preset lens synchronization position value PKT, a peak error due to the position of an AF detection region is corrected, in operation S 2634 . 
     Thereafter, in operation S 2635 , the driving amount of the focus lens  104  is determined by multiplying the focus deviation amount of the photographing lens ΔLVpk by the conversion coefficient KL. 
     Then, in operation S 2636 , the camera control unit  209  transmits, to the lens control unit  110 , the driving amount of the focus lens  104 , a command to drive the focus lens  104  in an inverse direction, and a command to drive the focus lens  104  at high speed at a target position, which is ascertained in operation S 2635 . In operation S 2636 , the lens drives the focus lens to the target position by initiating inverse direction driving, so that the lens is brought into focus. 
     In operation S 2637 , it is determined whether the full-pressing operation S 2  has been performed. If the full-pressing operation S 2  has not been performed, operation S 2606  of the process A 31  of  FIG. 26A  is conducted to continue capturing a moving picture and a continuous AF operation. If the shutter button is fully pressed (S 2 ) again, moving picture photographing is concluded, in operation S 2638 . Thereafter, operation A 1  of  FIG. 23  is performed again, and live view display is performed. 
     In operation A 33 , and if the peak value Vpk of the AF evaluation value is not greater than the preset lens synchronization position value PK T  in operation S 2633 , a focus lens driving stop command is issued, in operation S 2639 . Thereafter, the operations S 2637  and S 2638  are performed. 
     EMBODIMENT 2 
       FIG. 10  is a schematic diagram of an interchangeable-lens digital photographing apparatus  1 , according to another embodiment. 
     The lens driving actuator  105  and the focus lens position detecting sensor  106  are included in the image-forming optical system  101  in  FIG. 1 , whereas a camera which is an example of the digital photographing apparatus  1  of  FIG. 10  includes an image-forming optical system  101  without a lens driving actuator and a focus lens position detecting sensor. Instead, a body unit  200  of the camera of  FIG. 10  includes a lens driving actuator  230  for driving a focus lens group along an optical axis, and a position sensor  231  for sensing the position of the focus lens group, and a camera control unit  209  includes a camera memory  228 . 
     The camera memory  228  stores an error value ΔIB due to unique information about a lens or a difference between the lens and the frequency of AF detection, and a correction value ΔIBoff that is changed according to a focus detection region. As such, in the embodiment of  FIG. 10 , lens information may be stored and retained in the body unit  200 . Thus, even when an interchangeable photographing lens is old and thus information about the interchangeable photographing lens is not sufficient, the lens information stored in the body unit  200  may be used. 
     Components of  FIG. 10  corresponding to those of  FIG. 1  have the same or similar functions except for the above-described difference, so a detailed description thereof will be omitted. In addition, the digital photographing apparatus  1  of  FIG. 10  may also use the multi-divided AF detection region illustrated in  FIGS. 3A ,  4 A, or  5 . 
     An operation of the digital photographing apparatus  1  of  FIG. 10  is almost the same as that illustrated in  FIGS. 23 through 26  except that unnecessary operations, such as transmission of a driving amount, a direction change command, and a command to drive the focus lens fast at a target position from an interchangeable lens, are performed. In addition, the operation of the digital photographing apparatus  1  of  FIG. 10  may be different from that illustrated in  FIGS. 23 through 26  in terms of automatically controlled parts of a body unit of a digital photographing apparatus, a multi-AF method, and the like. Furthermore, focus detection regions, regarding which focus detection is performed during moving picture photographing, are the regions e 16  through e 18  of  FIG. 4A  in the operation of the digital photographing apparatus  1  of  FIG. 10 , whereas, in the operation illustrated in  FIGS. 23 through 26 , the focus detection regions are the regions e 19  through e 21  of  FIG. 5 . 
     The multi-AF method used in the digital photographing apparatus  1  of  FIG. 10  may be changed. For example, β m  may be set to be 1/100 in  FIG. 7B . Thus, when the magnification β m  of the central multi-point of the image is greater than 1/100, the central multi-point is selected. When the magnification β m  of the central multi-point of the image is less than 1/100, the nearest multi-point is selected. Since the multi-AF method is changed, it is determined whether the current position of the focus lens  104  is less than 1/100, in operation S 2410 . The magnification β m  of the central multi-point of the image may be changed according to the format of an imaging device. 
     The multi-AF method in the embodiment 2 refers to  FIG. 32 , which is described below. In  FIG. 32 , a magnification of a central multi-point of an image of  FIG. 31  is changed from 1/60 to 1/100, and thus the magnification β u  of the region directly over the central multi-point of the image may be further used during macro photographing. 
     EMBODIMENT 3 
     A digital photographing apparatus having a lens and a body unit integrally formed in one body will now be described by focusing on differences between the digital photographing apparatus having a lens and a body unit integrally formed in one body and the above-described digital photographing apparatuses  1 . 
       FIG. 11  is a schematic diagram of a digital photographing apparatus  2  having a lens and a body unit integrally formed in one body, according to another embodiment. 
     The digital photographing apparatus  2  according to the present embodiment has a structure and a function similar to those of the digital photographing apparatus  1  of  FIG. 1 , so only differences therebetween will be described. 
     Since the digital photographing apparatus  2  according to the present embodiment includes a lens  100  and a body unit  200  integrally formed in one body, the lens  100  cannot be replaced. In addition, since the lens  100  and the body unit  200  are integrally formed in one body as described above, the lens mount  109  and the camera mount  208  do not exist in the digital photographing apparatus  2 . 
     Thus, the camera control unit  209  directly controls the lens driving actuator  105 , the iris driving actuator  108 , etc. to drive the zoom lens  102 , the focus lens  104 , the iris  107 , etc. The camera control unit  209  directly receives position information from the zoom lens position detecting sensor  103  and the focus lens position detecting sensor  106 . In other words, the camera control unit  209  according to the present embodiment serves as the lens control unit  110  of  FIG. 1 . 
     The digital photographing apparatus  2  according to the present embodiment may further include a switch SMV for manipulating the digital photographing apparatus  2  to initiate a moving picture photographing operation. The digital photographing apparatus  2  according to the present embodiment operates in almost the same manner as the digital photographing apparatus  1  illustrated in  FIGS. 23 through 26 , but the digital photographing apparatus  2  previously retains information about interchangeable lenses. Thus, the digital photographing apparatus  2  does not require a process of inputting information about interchangeable lenses. 
       FIGS. 27 through 30  illustrate an operation of the digital photographing apparatus  2  illustrated in  FIG. 11 . 
       FIG. 27  illustrates a live view operation (an operation B 1 ) performed by a camera which is an example of a digital photographing apparatus, according to an embodiment. When a main switch SM of the camera is turned on and thus the camera is driven, manipulation of a key of the manipulation unit  207  is detected, in operation S 2701 . In operation S 2702 , a camera mode is set. Examples of the camera mode include a still picture mode, a moving picture mode, etc. In the embodiment 1, lens information about an interchangeable lens, which is necessary for a camera operation, is input. However, in the embodiment 3, the process of inputting the lens information is not required. An operation S 2703  and its subsequent operations are substantially the same as or similar to those in the embodiment 1, so a detailed description thereof will be omitted. 
       FIGS. 28A and 28B  are flowcharts of an operation of an all-in-one camera which is an example of an all-in-one digital photographing apparatus, according to an embodiment. 
     In a live view operation B 1  of  FIG. 27 , when the half-pressing operation S 1  is performed, an operation B 2  is initiated in  FIG. 28A . In the embodiment 3, the multi-AF detection region illustrated in  FIG. 3A  may be used, and the multi-AF method illustrated in  FIG. 31  may be used. The other features illustrated in  FIGS. 28A and 28B  are the same as or similar to those illustrated in  FIGS. 24A and 24B , so they refer to  FIGS. 24A and 24B . 
     In the embodiment illustrated in  FIGS. 28A and 28B , when scanning is performed in the Near direction, the AF scanning is fast, and a change in a viewing angle is large. On the other hand, when scanning is performed in the infinite direction, the AF scanning is slow, and a change in a viewing angle is small. Thus, the still picture mode prefers to begin by scaning toward the Near direction, and the moving picture mode prefers to begin by scanning toward the infinite direction. 
     When a subject is detected in a central multi-point in operation S 2808 , scanning continues in order to find a nearest subject even when the subject is detected in the central multi-point, in operation S 2810 . On the other hand, even when the nearest subject has been detected, scanning is performed to find a central multi-point. 
       FIG. 29  is a flowchart of an operation (B 3 ) of the digital photographing apparatus when the shutter release button is fully pressed (full-pressing operation S 2  is performed), according to an embodiment. 
     A case where the full-pressing operation S 2  is performed while a live view is being displayed after AF is completed is referred to as an operation B 3 . When the full-pressing operation S 2  is performed, it is determined whether the focus of a lens is detected, in operation S 2910 . The determination is repeated until the lens focus detection is performed. When the lens focus detection is performed, a still picture is captured, in operation S 2920 . In operation S 2930 , a still image captured for a predetermined period of time is displayed. Then, the method is fed back to operation B 1  of  FIG. 27 , and a live view is displayed. 
       FIGS. 30A and 30B  are flowcharts of applying the multi-AF method illustrated in  FIGS. 7A and 7B  to the contrast AF method in a moving picture mode of the digital photographing apparatus, according to an embodiment. 
     During moving picture photographing, the multi-AF region of  FIGS. 4A ,  4 B, or  5  may be used. Continuous AF is performed at low speed in order to reduce AF noise or a viewing angle change. 
     When the switch SMV for moving picture photographing is turned on, a moving picture photographing operation B 4  starts. When the moving picture photographing operation B 4  is initiated, moving picture photographing starts, in operation S 3001 , the focus lens is driven at high speed in the infinite direction, in operation S 3002 . The high-speed driving of the focus lens in the infinite direction is only an embodiment, and thus various modifications may be made thereto. 
     Operations S 3004  through S 3020 , S 3023 , and S 3024  are substantially the same as or similar to corresponding operations of  FIGS. 28A and 28B , so they refer to  FIGS. 28A and 28B . In operation S 3003 , it is determined whether the switch SMV for moving picture photographing has been turned on again or turned off. If it is determined that the switch SMV for moving picture photographing has been turned on again, the moving picture photographing is stopped, in operation S 3021 . In operation S 3022 , the driving of the focus lens is also stopped. 
       FIG. 31  is a flowchart of a multi-AF method, according to an embodiment. 
     First, in operation S 3110 , it is determined whether a magnification β near  of a nearest subject is greater than a magnification of 1/15. When the magnification β near  of the nearest subject is greater than the magnification of 1/15, current photographing is determined to be macro photographing. If the current photographing is determined to be macro photographing, a central multi-point of an image is selected, in operation S 3150 . On the other hand, if the magnification β near  of the nearest subject is equal to or less than the magnification of 1/15, it is determined whether the central multi-point is farthest from a photographer, in operation S 3120 . If the central multi-point is farthest from the photographer, a nearest multi-point is selected, in operation S 3140 . In other words, when the central multi-point is farthest from the photographer, a pattern as illustrated in  FIG. 7A  is formed. Thus, if the magnification β near  of the nearest subject is less than the magnification of 1/15, the nearest multi-point is selected. 
     If the central multi-point is not a region farthest from the photographer, a pattern as illustrated in  FIG. 7B  is formed. 
     In this case, it is determined whether a magnification β m  of the central multi-point is greater than a magnification of 1/60, in operation S 3130 . If the magnification β m  is greater than the magnification of 1/60, the central multi-point is selected, in operation S 3150 . Otherwise, the nearest multi-point is selected, in operation S 3140 . 
     After either the central multi-point or the nearest multi-point is selected, the direction of scanning is changed. 
       FIG. 32  is a flowchart of a multi-AF method, according to another embodiment. 
     The multi-AF method of  FIG. 32  may be used in the embodiment 2.  FIG. 32  is obtained by changing the magnification of the central multi-point of the image of  FIG. 31  from 1/60 to 1/100. In the multi-AF method of  FIG. 32 , it is suitable to use a magnification βu of a region directly over the central multi-point of an image during macro photographing. 
     First, in operation S 3210 , it is determined whether the magnification β near  of the central multi-point is greater than the magnification of 1/15. When the magnification β near  of the nearest subject is greater than the magnification of 1/15, a current photographing is determined to be macro photographing. If the current photographing is determined to be macro photographing, it is determined whether the magnification Bu of the region directly over the central multi-point is greater than the magnification of 1/15, in operation S 3250 . If the magnification Bu is greater than the magnification of 1/15, the central multi-point of the image is selected, in operation S 3260 . On the other hand, if the magnification Bu is equal to or less than the magnification of 1/15, a nearest multi-point is selected, in operation S 3240 . 
     On the other hand, when the magnification β near  of the nearest subject is not greater than the magnification of 1/15, it is determined whether the central multi-point is farthest from a photographer, in operation S 3220 . If the central multi-point is farthest from the photographer, the nearest multi-point is selected, in operation S 3240 . In other words, when the central multi-point is farthest from the photographer, a pattern as illustrated in  FIG. 7A  is formed. Thus, if the Magnification β near  of the nearest subject is less than the magnification of 1/15, the nearest multi-point is selected. 
     If the central multi-point is not a region farthest from the photographer, a pattern as illustrated in  FIG. 7B  is formed. 
     In this case, it is determined whether a magnification β m  of the central multi-point is greater than a magnification of 1/100, in operation S 3230 . If the magnification β m  is greater than the magnification of 1/100, the central multi-point is selected, in operation S 3260 . Otherwise, the nearest multi-point is selected, in operation S 3240 . 
     After either the central multi-point or the nearest multi-point is selected, the direction of scanning is changed. 
       FIG. 33  is a flowchart of a method of applying a multi-AF operation C 1  to the contrast AF method in a digital photographing apparatus, according to an embodiment. 
     In operation S 3310 , a captured image is divided into multi-points. Operation S 3310  may refer to the examples illustrated in  FIGS. 3 through 5 . 
     In operation S 3320 , a focus lens is driven in a Near direction or an infinite direction to perform scanning.  FIGS. 12 through 19  illustrate an example of the scanning in the Near direction.  FIGS. 20 through 22  illustrate an example of the scanning in the ∞ direction. 
     In operation S 3330 , AF peak values are detected from the multi-points, respectively, during the scanning. Thereafter, in operation S 3340 , it is determined whether both the AF peak values of a central multi-point and a near region of the captured image have been detected. If neither of the AF peak values is detected, the scanning continues. 
     In operation S 3320 , scanning is not performed all the way to a final end in the Near direction or in the ∞ direction, that is, a region from which a peak is not likely to be detected is not scanned. The possibility that a peak is detected from a region is determined according to whether an AF evaluation value monotonically increases or monotonically decreases at each lens synchronization position. This refers to  FIG. 9 . 
     Even when a peak of the central multi-point is detected in the scanning performed in operation S 3320 , if a peak of a nearest multi-point is not detected, the focus lens performs scanning from the infinite direction to the Near direction, and the scanning in the Near direction continues. 
     Even when the peak of the nearest multi-point is detected, if the peak of the central multi-point is not detected, the focus lens performs scanning from the Near direction to the infinite direction, and the scanning in the infinite direction continues. However, if the peak of the central multi-point is not detected even when the scanning was performed up to a predetermined ratio, further scanning is not performed. In this case, the predetermined magnification may be 1/60 or the like. This scanning process refers to the embodiment of  FIG. 17 . 
     If it is determined in operation S 3340  that both AF peak values of the central multi-point and near region of the image on the display  206  are detected, further scanning is not performed, and a main subject is determined according to the multi-AF method, in operation S 3350 . The multi-AF method refers to  FIGS. 7A and 7B . The multi-AF method illustrated in  FIGS. 7A and 7B  is only an embodiment, so various changes may be made thereto. 
     In operation S 3360 , the lens is focused on a peak corresponding to the main subject. 
     In a digital photographing apparatus according to various embodiments, when AF peaks of a subject of a central multi-point and a subject of a near region are detected, further scanning is not performed. In addition, scanning is not performed on a region from which it is difficult to detect a peak, so that fast and accurate AF may be performed. 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     For the purposes of promoting an understanding of the principles of the invention, reference has been made to the embodiments illustrated in the drawings, and specific language has been used to describe these embodiments. However, no limitation of the scope of the invention is intended by this specific language, and the invention should be construed to encompass all embodiments that would normally occur to one of ordinary skill in the art. The terminology used herein is for the purpose of describing the particular embodiments and is not intended to be limiting of exemplary embodiments of the invention. 
     The apparatus described herein may comprise a processor, a memory for storing program data to be executed by the processor, a permanent storage such as a disk drive, a communications port for handling communications with external devices, and user interface devices, including a display, keys, etc. When software modules are involved, these software modules may be stored as program instructions or computer readable code executable by the processor on a non-transitory computer-readable media such as the semiconductor memory  210  illustrated in  FIG. 2 , random-access memory (RAM), read-only memory (ROM), CD-ROMs, DVDs, magnetic tapes, hard disks, floppy disks, and optical data storage devices. The computer readable recording media may also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. This media can be read by the computer, stored in the memory, and executed by the processor. 
     Also, using the disclosure herein, programmers of ordinary skill in the art to which the invention pertains can easily implement functional programs, codes, and code segments for making and using the invention. 
     The invention may be described in terms of functional block components and various processing steps. Such functional blocks may be realized by any number of hardware and/or software components configured to perform the specified functions. For example, the invention may employ various integrated circuit components, e.g., memory elements, processing elements, logic elements, look-up tables, and the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, where the elements of the invention are implemented using software programming or software elements, the invention may be implemented with any programming or scripting language such as C, C++, Java, assembler, or the like, with the various algorithms being implemented with any combination of data structures, objects, processes, routines or other programming elements. Functional aspects may be implemented in algorithms that execute on one or more processors. Furthermore, the invention may employ any number of conventional techniques for electronics configuration, signal processing and/or control, data processing and the like. Finally, the steps of all methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. 
     For the sake of brevity, conventional electronics, control systems, software development and other functional aspects of the systems (and components of the individual operating components of the systems) may not be described in detail. Furthermore, the connecting lines, or connectors shown in the various figures presented are intended to represent exemplary functional relationships and/or physical or logical couplings between the various elements. It should be noted that many alternative or additional functional relationships, physical connections or logical connections may be present in a practical device. The words “mechanism” and “element” are used broadly and are not limited to mechanical or physical embodiments, but may include software routines in conjunction with processors, etc. 
     The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. Numerous modifications and adaptations will be readily apparent to those of ordinary skill in this art without departing from the spirit and scope of the invention as defined by the following claims. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the following claims, and all differences within the scope will be construed as being included in the invention. 
     No item or component is essential to the practice of the invention unless the element is specifically described as “essential” or “critical”. It will also be recognized that the terms “comprises,” “comprising,” “includes,” “including,” “has,” and “having,” as used herein, are specifically intended to be read as open-ended terms of art. The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless the context clearly indicates otherwise. In addition, it should be understood that although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms, which are only used to distinguish one element from another. Furthermore, recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.