JP4760894B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus such as a digital camera.

  In an imaging apparatus such as a digital camera, there is an imaging apparatus capable of implementing both of two AF methods (for example, a relatively high-speed phase difference AF method and a relatively high-precision contrast AF method) (see Patent Document 1). ).

  For example, in Patent Document 1, a mode in which contrast AF is executed and a mode in which phase difference AF is mainly executed are selected by switching according to an operator's setting operation, and an AF operation is executed in the selected mode. Are listed. In the former mode, phase difference AF is executed when the shutter button is half-pressed, and in the latter mode, phase difference AF is executed when the shutter button is half-pressed, and then the shutter is released. When the button is fully pressed, contrast AF is executed.

JP 2001-281530 A Japanese Patent Laid-Open No. 10-229516

  As described above, in the technique of Patent Document 1, the operator switches the setting related to the AF method.

  However, even if the operator performs a switching operation, it is often difficult to determine which AF method is appropriate at that time, and it is difficult to immediately switch to the appropriate AF method.

  In Patent Document 2, it is described that the two systems are switched according to the temperature detected by the temperature sensor, but such a technique is insufficient to switch both systems appropriately.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus capable of properly using each AF system in an imaging apparatus having a plurality of AF systems.

The present invention is an image pickup apparatus, which receives light from a subject on a predetermined imaging surface via an imaging lens, photoelectrically converts a subject image to generate a photographed image, and light from the subject. Phase difference detection means for receiving a light and generating a phase difference detection signal corresponding to the degree of focus of the subject image, and evaluation value calculation for obtaining a predetermined evaluation value corresponding to the contrast of the subject image based on the photographed image And a plurality of AF methods that selectively or combinedly use the phase difference detection signal from the phase difference detection unit and the predetermined evaluation value for the photographed image according to the photographing condition of the subject. determination means for AF scheme, and display means for displaying a determination result by the determination means prior AF operation, in response to operation by the operator, from among the plurality of AF method, actual AF control operation And a determining means for determining a AF method used.

  According to the present invention, in an imaging apparatus having a plurality of AF methods, the optimum AF method is determined according to the shooting situation of the subject, so that each AF method can be properly used.

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

<1. First Embodiment>
<1-1. Outline of configuration>
1 and 2 are diagrams showing an external configuration of the imaging apparatus 1 (1A) according to the first embodiment of the present invention. Here, FIG. 1 is a front external view of the image pickup apparatus 1, and FIG. 2 is a rear external view of the image pickup apparatus 1. This imaging device 1A is configured as a lens interchangeable single-lens reflex digital camera.

  As shown in FIG. 1, the imaging device 1 </ b> A includes a camera body (camera body) 2. An interchangeable photographic lens unit (interchangeable lens) 3 can be attached to and detached from the camera body 2.

  The photographic lens unit 3 mainly includes a lens barrel 36, a lens group 37 (see FIG. 3) provided in the lens barrel 36, a diaphragm, and the like. The lens group 37 (shooting optical system) includes a focus lens that changes the focal position by moving in the optical axis direction.

  The camera body 2 includes an annular mount Mt to which the photographing lens unit 3 is attached at the front center, and an attach / detach button 89 for attaching / detaching the photographing lens unit 3 near the annular mount Mt. Yes.

  Further, the camera body 2 is provided with a mode setting dial 82 in the upper left part of the front surface and a control value setting dial 86 in the upper right part of the front surface. By operating the mode setting dial 82, various camera modes (such as various shooting modes (people shooting mode, landscape shooting mode, full-auto shooting mode, etc.), playback modes for playing back captured images, and between external devices It is possible to perform a setting operation (switching operation) including a communication mode for performing data communication. Further, by operating the control value setting dial 86, it is possible to set control values in various shooting modes.

  Further, the camera body 2 includes a grip portion 14 for a photographer to hold at the left end of the front. A release button 11 for instructing the start of exposure is provided on the upper surface of the grip portion 14. A battery storage chamber and a card storage chamber are provided inside the grip portion 14. For example, four AA batteries are housed in the battery compartment as a power source for the camera, and a memory card 90 (see FIG. 3) for recording image data of a photographed image can be attached to and detached from the card compartment. It is designed to be stored in.

  The release button 11 is a two-stage detection button that can detect two states, a half-pressed state (S1 state) and a fully-pressed state (S2 state). When the release button 11 is half-pressed to enter the S1 state, a preparation operation (for example, an AF control operation and an AE control operation) for acquiring a recording still image (main captured image) related to the subject is performed. When the release button 11 is further pushed into the S2 state, an exposure operation related to a subject image (light image of the subject is performed using the imaging device 5 (described later) using the imaging element 5 (described later), and the exposure operation is performed. A series of operations for applying predetermined image processing to the obtained image signal is performed.

  In FIG. 2, an AF mode changeover switch 87 is provided in the lower right portion of the camera body 2. The changeover switch 87 is configured as a three-stage slide switch, and is an operation member that can select any one of a plurality of modes (here, three modes MD1, MD2, and MD3) as an AF mode. . Specifically, depending on the position of the slide portion of the changeover switch 87, a phase difference AF fixed mode MD1 that uses the phase difference AF method fixedly, a contrast AF fixed mode MD2 that uses the contrast AF method fixedly, A desired AF mode is set from three modes including an automatic switching mode MD3 that can automatically switch between the phase difference AF method and the contrast AF method.

  In FIG. 2, a finder window (eyepiece window) 10 is provided at the upper center of the back surface of the camera body 2. The photographer can determine the composition by viewing the viewfinder window 10 and visually recognizing the light image of the subject guided from the photographing lens unit 3. That is, it is possible to determine the composition using an optical finder.

  In the imaging apparatus 1A according to this embodiment, a plurality of time-series images (live view images) acquired by the imaging element are displayed on the rear monitor 12 (described later). The operator can determine the composition using a live view image in a moving image form.

  As will be described later, the composition determination operation by the optical viewfinder and the composition determination operation by the live view display are switched according to the AF method or the like employed at that time.

  In FIG. 2, a rear monitor 12 is provided in the approximate center of the rear surface of the camera body 2. The rear monitor 12 is configured as a color liquid crystal display (LCD), for example. The rear monitor 12 can display a menu screen for setting shooting conditions and the like, and can reproduce and display a captured image recorded in the memory card 90 in the reproduction mode. Depending on the AF mode selection status, a plurality of time-series images (that is, moving images) acquired by the image sensor 5 are displayed on the rear monitor 12 as “live view images”.

  A main switch 81 is provided at the upper left of the rear monitor 12. The main switch 81 is a two-point slide switch. When the contact is set to the left “OFF” position, the power is turned off. When the contact is set to the right “ON” position, the power is turned on.

  A direction selection key 84 is provided on the right side of the rear monitor 12. This direction selection key 84 has a circular operation button, and it is possible to detect a pressing operation in four directions of up, down, left and right, and a pressing operation in four directions of upper right, upper left, lower right and lower left on this operation button. It has become. In addition, the direction selection key 84 is configured to detect a pressing operation of a push button at the center, in addition to the pressing operations in the eight directions.

  A setting button group 83 including a plurality of buttons for setting a menu screen, deleting an image, and the like is provided on the left side of the rear monitor 12.

<1-2. Functional block>
Next, an overview of the functions of the imaging apparatus 1A will be described with reference to FIG. FIG. 3 is a block diagram illustrating a functional configuration of the imaging apparatus 1A.

  As shown in FIG. 3, the imaging apparatus 1 </ b> A includes a phase difference AF module (hereinafter also simply referred to as an AF module) 20, a photometric sensor 40, an operation unit 80, an overall control unit 101, a mirror mechanism 6, a shutter 4, and an image sensor 5. , An A / D conversion circuit 52, a digital signal processing circuit 50, an image memory 56, and the like.

  The AF module 20 has a phase difference detection function for receiving light from a subject (specifically, light entering through the mirror mechanism 6) and generating a phase difference detection signal corresponding to the degree of focus of the subject image. Have.

  The photometric sensor 40 has a function of measuring the brightness of the subject image, in other words, the intensity of light from the subject. An AE control operation is performed based on the output of the photometric sensor 40, and the brightness of the captured image is adjusted.

  The operation unit 80 includes various buttons and switches including the release button 11 (see FIG. 1). In response to a user input operation on the operation unit 80, the overall control unit 101 implements various operations.

  The overall control unit 101 is configured as a microcomputer and mainly includes a CPU, a memory, a ROM, and the like. The overall control unit 101 implements various functions by reading a program stored in the ROM and executing the program by the CPU.

  The overall control unit 101 functionally realizes the AF control unit 120, the display control unit 125, the warning control unit 126, the mirror control unit 127, and the like by executing the above-described program.

  The AF control unit 120 adopts an AF method that is determined to be the optimum AF method for the current shooting situation of the subject from among a plurality of AF methods, and executes an AF operation with driving of the taking lens It is a control part. The AF control unit 120 includes a phase difference AF control unit 121, a contrast AF control unit 122, a determination unit 123, and a drive control unit 124.

  The phase difference AF control unit 121 performs an automatic focusing (AF) operation using a phase difference AF method. Specifically, the phase difference AF control unit 121 specifies the position of the photographing lens (more specifically, the focus lens) at the time of focusing (focus lens position) based on the phase difference detection signal from the AF module 20. A focusing lens position specifying operation is performed. The phase difference AF control unit 121 also executes an AF drive operation (lens drive operation) for moving the photographing lens (focus lens) to the focus lens position in cooperation with the drive control unit 124.

  The contrast AF control unit 122 performs an automatic focusing (AF) operation using a contrast AF method. Specifically, the contrast AF control unit 122 performs an evaluation value calculation operation for obtaining evaluation values corresponding to the contrast of the subject image for a plurality of captured images respectively corresponding to different lens positions, and optimizes the evaluation values (for example, And a focusing lens position specifying operation for specifying the lens position to be minimized as the focusing lens position. The contrast AF control unit 122 also performs an AF driving operation for moving the photographing lens (focus lens) to the focus lens position in cooperation with the drive control unit 124.

  In addition, the determination unit 123 selects an optimum one from a plurality of AF methods including a phase difference AF method using a phase difference detection signal and a contrast AF method using an evaluation value related to a captured image, depending on the shooting situation of the subject. A proper AF method is determined. The determination result by the determination unit 123 (that is, which method is the optimum AF method) is displayed on the rear monitor 12 as “recommended display (recommended display)” or the like and can be visually recognized by the operator. The determination operation in the determination unit 123 will be described in detail later.

  The drive control unit 124 is a control unit that controls lens driving. The drive control unit 124 adopts the AF method determined by the determination unit 123 as the optimum AF method for the current shooting situation of the subject from among a plurality of AF methods, and uses the phase difference AF control unit 121. In cooperation with the contrast AF control unit 122, the photographing lens is actually driven.

  The phase difference AF control unit 121 and the contrast AF control unit 122 communicate with the lens side control unit 31 of the photographing lens unit 3 via the drive control unit 124 and transmit the control signal to drive the lens drive unit 38. Thus, the focus lens included in the lens group 37 of the photographing lens unit 3 is moved in the optical axis direction. Further, the position of the focus lens is detected by the lens position detection unit 39 of the photographing lens unit 3, and data indicating the position of the focus lens is sent from the lens side control unit 31 to the overall control unit 101 on the main body side.

  The display control unit 125 controls display contents on a display unit such as the rear monitor 12. For example, the recommendation display described above is displayed under the control of the display control unit 125.

  The warning control unit 126 is a control unit that issues a warning that the AF method is switched. The warning control unit 126 controls warning display in cooperation with the display control unit 125, for example. Specifically, in a situation where the AF method currently employed is different from the AF method that is scheduled to be adopted in response to the release button 11 being in the half-pressed state S1, the operator (photographer) is notified. Control is performed so that a display for notifying the situation is output to the rear monitor 12. The operator can know that the AF method is switched by this warning. As will be described later, based on the correspondence between the AF method and the composition determination method, it can be understood that switching of the AF method means switching of the composition determination method. Therefore, a warning that the AF method is switched corresponds to a warning that the composition determination method is switched.

  The mirror control unit 127 controls state switching between a state in which the mirror mechanism 6 is retracted from the optical path (mirror up state) and a state in which the mirror mechanism 6 blocks the optical path (mirror down state). The mirror control unit 127 switches between a mirror-up state and a mirror-down state by driving a mirror switching motor (not shown).

  An image sensor (here, a CCD sensor (also simply referred to as a CCD)) 5 converts a subject image received by the imaging surface into an electrical signal by a photoelectric conversion action, and generates an image signal related to the actual captured image. The imaging element 5 is also expressed as a sensor (image sensor) for acquiring a captured image.

  The image sensor 5 responds to drive control signals (accumulation start signal and accumulation end signal) input from a timing control circuit (not shown), and exposes (photoelectrically) the subject image formed on the light receiving surface (imaging surface). Charge accumulation by conversion) is performed, and an image signal related to the subject image is generated.

  The image signal (analog signal) acquired by the image sensor 5 is converted into a digital signal by the A / D conversion circuit 52. The image signal converted into the digital signal is input to the digital signal processing circuit 50.

  The digital signal processing circuit 50 performs digital signal processing on the image signal input from the A / D conversion circuit 52. Specifically, signal processing such as black level correction processing, white balance (WB) processing, and γ correction processing is performed. The image signal (image data) after the signal processing is stored in the image memory 56.

  The image memory 56 is a high-speed accessible image memory for temporarily storing generated image data, and has a capacity capable of storing image data for a plurality of frames.

  At the time of actual photographing, the image data temporarily stored in the image memory 56 is subjected to image processing (such as compression processing) as appropriate in the overall control unit 101 and then stored in the memory card 90.

<1-3. Arrangement of each member when determining each composition>
Next, a photographing operation including a composition determining operation in the imaging apparatus 1A will be described. As described above, in the imaging apparatus 1A, composition determination (framing) can be performed using an optical viewfinder (also referred to as an optical viewfinder (OVF)) configured with a viewfinder optical system and the like. The composition can also be determined using a live view image displayed on the rear monitor 12 (described later). Note that the finder function realized using the image sensor 5 and the rear monitor 12 is also called an electronic viewfinder (EVF) because it visualizes a light image of a subject after converting it into electronic data.

  In the imaging apparatus 1A, when the operator selects the AF mode by operating the changeover switch 87, the AF mode is set according to the selection result, and the composition is determined according to the selected AF mode. The method will be determined automatically.

  Specifically, when the phase difference AF fixed mode MD1 is selected, the phase difference AF method is fixedly selected as the AF method, and the composition determination operation is always performed by the optical finder. In this case, the composition determination operation by the live view display cannot be performed.

  When the contrast AF fixed mode MD2 is selected, the contrast AF method is fixedly selected as the AF method, and the composition determination operation is always performed by live view display. In this case, the composition determination operation by the optical finder cannot be performed.

  When the automatic switching mode MD3 is selected, the imaging device 1A selects an appropriate AF method according to the shooting situation of the subject. The composition determination method is also determined according to the selected AF method. Specifically, during the period in which the phase difference AF operation is performed, only the composition determination operation by the optical finder is possible, and the composition determination operation by the live view display cannot be performed. On the other hand, during the period in which the contrast AF operation is performed, only the composition determination operation by the live view display is possible, and the composition determination operation by the optical finder cannot be performed.

  In the imaging apparatus 1A, there is a correspondence as described above between the AF method and the composition determination method.

  4 and 5 are cross-sectional views of the imaging apparatus 1A. FIG. 4 shows a composition determination operation using an optical finder (or OVF), and FIG. 5 shows a composition determination operation using a live view display (or EVF).

  When the composition determination operation by the optical finder is performed, the mirror mechanism 6 is arranged so as to be in the mirror down state until the release button 11 is fully pressed S2 (see FIG. 4).

  Specifically, as shown in FIG. 4, a mirror mechanism 6 is disposed on an optical path (imaging optical path) from the imaging lens unit 3 to the image sensor 5. The mirror mechanism 6 has a main mirror 61 (main reflection surface) that reflects light from the photographing optical system upward. The main mirror 61 is configured as a half mirror, for example, and transmits part of the light from the photographing optical system. The mirror mechanism 6 also includes a sub mirror 62 (sub reflective surface) that reflects light transmitted through the main mirror 61 downward. The light reflected downward by the sub mirror 62 is guided to the AF module 20 and is incident thereon, and a phase difference detection signal is detected.

  As shown in FIG. 4, when the main mirror 61 and the sub mirror 62 of the mirror mechanism 6 are arranged on the optical path of the subject image from the photographing lens unit 3, the subject image is the main mirror 61, the pentamirror 65, and the eyepiece 67. To the viewfinder window 10. As described above, the finder optical system including the main mirror 61, the pentamirror 65, and the eyepiece lens 67 transmits the observation light beam, which is a light beam from the photographing optical system and reflected by the main mirror 61, to the finder window 10. It is possible to lead to. A part of the light that reaches the optical element 68 (half mirror) disposed between the pentamirror 65 and the eyepiece 67 is reflected by the optical element 68 and reaches the photometric sensor 40.

  On the other hand, when the composition determination operation by live view display is performed, the mirror mechanism 6 is arranged so as to be in the mirror up state until the release button 11 is fully pressed S2 (see FIG. 5). At this time, the subject image from the photographic lens unit 3 enters the image sensor 5.

  Specifically, as shown in FIG. 5, the mirror mechanism 6 is retracted from the photographing optical path. Specifically, the main mirror 61 and the sub mirror 62 are retracted upward so as not to block the light (subject image) from the photographing optical system. Then, the light from the photographing lens unit 3 passes through the opened shutter 4 and reaches the image sensor 5, and the image sensor 5 generates an image signal of the subject based on the received light flux by photoelectric conversion. As described above, the light from the subject is guided to the image sensor 5 through the photographing lens unit 3, thereby obtaining a photographed image (photographed image data) relating to the subject.

  The image sensor 5 acquires captured images related to the subject image at predetermined time intervals based on the incident light. Live view display is performed using the time-series captured images. Further, during the contrast AF operation, the AF operation is performed based on a plurality of photographed images photographed according to different lens positions.

  In any of the methods for determining the composition, when the release button 11 is fully depressed S2, the mirror mechanism 6 is arranged so as to be in the mirror up state (see FIG. 5), and the exposure operation is performed. Be started. As a result, an operation of acquiring a recording still image (also referred to as an actual captured image) related to the subject is executed.

  Specifically, as shown in FIG. 5, at the time of exposure, the mirror mechanism 6 is retracted from the photographing optical path. Specifically, the main mirror 61 and the sub mirror 62 are retracted upward so as not to block the light (subject image) from the photographic optical system, and the light from the photographic lens unit 3 is synchronized with the opening timing of the shutter 4. Reach 5 The imaging element 5 generates an image signal of the subject based on the received light flux by photoelectric conversion. As described above, the light from the subject is guided to the image sensor 5 through the photographing lens unit 3, thereby obtaining a photographed image (photographed image data) relating to the subject.

<1-4. Operation>
<Overview>
6 to 11 are flowcharts showing operations in the imaging apparatus 1A. FIG. 6 is a flowchart showing the overall operation, and FIGS. 7 to 11 are flowcharts showing detailed operations of a part (steps SP11, SP30, SP40, SP12, SP14).

  First, an outline of the operation will be described with reference to FIG.

  The operation in FIG. 6 assumes an operation in a state where the power is turned on by operating the main switch 81 and the “shooting mode” is set by operating the mode setting dial 82.

  Further, regarding the AF mode selection setting, the recommended mode display (recommended display) setting, and the warning setting, it is assumed that each setting content is determined (updated) in advance according to a predetermined operation.

  Specifically, as described above, the AF mode selection setting is determined (updated) in accordance with the AF mode selection operation by the operator.

  Here, the case where the AF mode selection setting is performed using the changeover switch 87 is illustrated, but the present invention is not limited to this, and a display screen (AF mode selection setting screen) G1 as shown in FIG. The AF mode selection setting may be updated in accordance with an AF mode selection operation using the direction selection key 84. In the screen G1 of FIG. 12, a phase difference AF fixed mode (indicated as “phase difference AF method” in the figure) MD1 that uses the phase difference AF method fixedly, and a contrast AF fixed mode that uses the contrast AF method fixedly ( In the figure, it is expressed as “video AF system”) MD2 and an automatic switching mode (indicated by “automatic selection system” in the figure) MD3 that can automatically switch between a plurality of AF systems including a phase difference AF system and a contrast AF system. The state in which the automatic switching mode MD3 is selected from the three modes including the above is shown.

  In the imaging apparatus 1A, recommended display settings are determined (updated) in accordance with a recommended display selection operation using the display screen (setting screen related to recommended display settings) G2 and the direction selection key 84 as shown in FIG. ) Specifically, the cursor CR is moved by operating the left / right / up / down button of the direction selection key 84 to select a selection item in the screen G2, and then the push button at the center of the direction selection key 84 is pressed down to select a desired item. A selection item can be selected. FIG. 13 shows a state in which the recommendation display is set to ON.

  Similarly, the setting (warning setting) regarding on / off of the warning display (described later) is also updated according to the setting operation by the operator.

  The operation shown in FIG. 6 is executed in a state where various settings as described above are made.

  As shown in FIG. 6, the operations of steps SP11 to SP16 are repeatedly executed until it is determined in step SP17 that the release button 11 is in the half-pressed state S1. In other words, until it is determined in step SP17 that the release button 11 has been half-pressed S1, in the period in which steps SP11 to SP16 are repeatedly executed, the AF driving operation for driving the photographing lens is not performed. On the other hand, when it is determined that the release button 11 is half-pressed S1, an AF driving operation (step SP18) for actually driving the photographing lens is executed. Thereafter, in step SP19, it is determined whether or not the release button 11 has been fully pressed. If it is determined that the fully depressed state S2 has not been established, the process returns to step SP11 again, and the operations of steps SP11 to SP18 are repeated. On the other hand, when it is determined that the fully-pressed state is set to S2, the process proceeds to step SP20, and a main photographing operation with an exposure operation is performed.

<AF method determination processing>
First, in step SP11 of FIG. 6, an optimum AF method determination process is performed. In step SP11, it is determined which AF method is the optimum AF method among a plurality of AF methods in accordance with various detection results reflecting the shooting situation of the subject. The contents of this determination process will be described in detail later.

<AF method correction processing>
In step SP12, the determination result in step SP11 is corrected in accordance with the setting contents of the AF mode selection setting determined in advance by the AF mode selection operation, and the AF method actually used in the AF driving operation in step SP18 is changed. It is determined.

  Specifically, as shown in FIG. 10, when the phase difference AF fixed mode MD1 or the contrast AF fixed mode MD2 is set in the AF mode selection setting, the determination process in step SP11 is not reflected. The predetermined AF method is adopted as the AF method used for the actual AF control operation (step SP18). Specifically, when the phase difference AF fixed mode MD1 is set, the phase difference AF method is determined as the AF method used for the actual AF control operation (step SP18) (steps SP51 and SP54). . If the contrast AF fixed mode MD2 is set, the contrast AF method is determined as the AF method used for the actual AF control operation (step SP18) (steps SP51 and SP55).

  On the other hand, when the automatic switching mode MD3 is set in the AF mode selection setting, the result of the determination process in step SP11 is used as it is. Specifically, when the phase difference AF method is determined as the optimum AF method in step SP11, the “phase difference AF method” is determined as the AF method used in the actual AF control operation (step SP18). (Steps SP51, SP52, SP54). If the contrast AF method is determined as the optimum AF method in step SP11, the “contrast AF method” is determined as the AF method used in the actual AF control operation (step SP18) (step SP51, SP53, SP55). Further, when the combined method (described below) is determined as the optimum AF method in step SP11, the combined AF method is determined as the AF method used in the actual AF control operation (step SP18) (step SP51). , SP56).

  Here, simply speaking, the “combination method” is a method in which both the phase difference AF method and the contrast AF method are used together. As the AF operation by the combined method, after performing the AF driving operation by the phase difference AF method (see FIG. 4), the arrangement of the mirror mechanism 6 is changed and the AF driving operation by the contrast AF method (see FIG. 5) is performed. What to do is illustrated.

  This “combination method” is also expressed as a method in which the phase difference detection signal from the AF module 20 and the evaluation value corresponding to the contrast are used in combination. On the other hand, the “phase difference AF method” is an AF method that selectively uses the phase difference detection signal from the AF module 20 out of the phase difference detection signal from the AF module 20 and the evaluation value corresponding to the contrast. Expressed. The “contrast AF method” is also expressed as an AF method that selectively uses an evaluation value corresponding to the contrast among the phase difference detection signal from the AF module 20 and the evaluation value corresponding to the contrast.

<Recommended display>
Refer to FIG. 6 again. When the processing of steps SP11 and SP12 is performed, recommendation display is performed on the condition that “recommended display setting” is set to ON (steps SP13 and SP14). Note that when the “recommended display setting” is set to off, the recommended display is not performed.

  FIG. 11 is a flowchart showing the detailed operation of the recommendation display process (step SP14). In step SP14, the determination result in step SP11 is displayed on the rear monitor 12.

  As shown in FIG. 11, when it is determined that the phase difference AF is the optimum AF method, the rear monitor 12 displays that the optimum AF method is “phase difference AF” (step SP61). , SP64).

  When it is determined that the contrast AF is the optimum AF method, the fact that the optimum AF method is “contrast AF” is displayed on the rear monitor 12 (steps SP62 and SP65).

  In addition, when it is determined that the combined method using the phase difference AF and the contrast AF is the optimum AF method, the fact that the optimum AF method is the “combined method (phase difference AF + contrast AF)”. Is displayed on the rear monitor 12 (steps SP63 and SP66).

  FIG. 14 is a diagram illustrating an example of “recommendation display”. In FIG. 14, the characters “phase difference AF” are displayed in the display field D <b> 1 near the upper edge of the rear monitor 12, indicating that “phase difference AF” is the recommended AF method. When live view display is executed, the characters “phase difference AF” are displayed superimposed on the live view image. On the other hand, when the composition is determined by the optical viewfinder, various pieces of shooting information may be displayed in a portion other than the display column D1.

  When the other method is the recommended AF method, the name of the recommended AF method is displayed in the display field D1 in the same manner.

  Note that the “recommendation display” is not limited to such an embodiment. For example, as shown in FIG. 15, after selecting all three options, a check mark (for example, a red circle) is added to the check box to the left of each option, so that an option with a check mark is selected. It may be shown that it is done. Alternatively, as shown in FIG. 16, all the three options may be displayed, and the selected option may be displayed in the largest size to indicate the selected option.

  According to such a recommendation display, the operator can recognize which method is the most suitable AF method according to the current shooting situation of the subject, and can switch the AF method appropriately. become.

  For example, when the phase difference AF fixed mode MD1 or the contrast AF fixed mode MD2 is selected, after the optimum AF method is obtained by the determination unit 123, the optimum AF method which is the determination result is recommendedly displayed. It is possible to prompt the operator to perform a switching operation. According to this, when the phase difference AF fixed mode MD1 or the contrast AF fixed mode MD2 is selected and there is an AF method more suitable than the AF method corresponding to the currently selected AF mode, the operator's By the switching operation, it is possible to switch to the mode in which the other AF method which is the optimum AF method is fixedly selected.

  Also, in the automatic switching mode MD3, it can be seen in which AF method it is preferable to execute the AF operation. Therefore, the switching operation to the phase difference AF fixed mode MD1 or the contrast AF fixed mode MD2 is performed as necessary. Is possible.

<Warning display>
In the next step SP15, it is determined whether or not the warning display setting is on. If the warning display setting is ON, a warning display is performed in step SP16, and if the warning display setting is OFF, the warning display is not performed and the process proceeds to step SP17. The warning operation in step SP16 is executed only when the automatic switching mode MD3 is selected, and the warning operation is not executed when the other modes MD1 and MD2 are selected.

  In the imaging apparatus 1A, it is possible to set whether to use the live view display or the optical viewfinder as a main composition determination operation in the automatic switching mode MD3 by a separate setting operation. In the following description, it is assumed that one of the desired composition determination operations is selected by an operator's setting operation or the like.

  In the imaging apparatus 1A, as shown in FIG. 5, when performing live view display, the main mirror 61 and the sub mirror 62 of the mirror mechanism 6 are retracted from the optical path so that the light from the subject reaches the imaging element 5. There is a need. Further, the AF module 20 can detect the phase difference signal in the state of FIG. 4, but cannot detect the phase difference detection signal in the arrangement state of FIG. Therefore, in this imaging apparatus 1A, the live view display operation and the AF operation by the phase difference AF method cannot be executed simultaneously. In this imaging apparatus 1A, when the automatic switching mode MD3 is set and the phase difference AF method is determined to be the optimum AF method in step SP11, the release button 11 is half-pressed during live view display. When the AF operation is started in response to this, the transition operation from the live view display execution state (FIG. 5) to the state where the phase difference AF is performed (FIG. 4) is executed, and the live view display is interrupted.

  Therefore, when the imaging apparatus 1A is in the live view display execution state (FIG. 5) and is set to the automatic switching mode MD3 and it is determined in step SP11 that the phase difference AF method is the optimum AF method, AF is performed. A warning that the method is switched to the phase difference AF method (that is, a warning for interrupting the live view display) is issued. According to such a warning, the operator can predict that the live view display is interrupted when the AF operation is started in response to the half-press operation of the release button 11. Therefore, it is possible to avoid the “unexpected hit” in which the live view display is suddenly interrupted.

  In the imaging apparatus 1A, when the main mirror 61 is retracted from the optical path (FIG. 5), the subject image cannot be viewed through the finder window 10. In other words, in order to perform the composition determination operation by the optical finder, as shown in FIG. 4, the main mirror 61 and the sub mirror 62 of the mirror mechanism 6 are arranged on the optical path, and the light from the subject passes through the pentamirror 65. To the viewfinder window 10. However, the image sensor 5 can obtain a subject image in the state of FIG. 5, but in the state of FIG. 4, light from the subject does not reach the image sensor 5 and the image sensor 5 cannot obtain a subject image. For this reason, in this imaging apparatus 1A, the composition determination operation by the optical finder and the AF operation by the contrast AF method cannot be executed simultaneously. Therefore, in this imaging apparatus 1A, when the automatic switching mode is set and the contrast AF method is determined to be the optimum AF method in step SP11, the release button 11 is being executed during the composition determination by the optical finder. When the AF operation is started in response to the half-press operation, the transition operation from the composition determination execution state by the optical finder (FIG. 4) to the state in which contrast AF is performed (FIG. 5) is executed and the composition determination by the optical finder is performed. Cannot be done.

  Therefore, when the imaging apparatus 1A is in the composition determination execution state by the optical finder (FIG. 4) and is set to the automatic switching mode and it is determined in step SP11 that the contrast AF method is the optimum AF method, AF is performed. A warning that the method is switched to the contrast AF method (that is, a warning of composition interruption by the optical finder) is issued. According to such a warning, the operator can predict that the composition cannot be determined by the optical finder when the AF operation is started in response to the half-pressing operation of the release button 11. Therefore, it is possible to avoid the “unexpected hit” that the composition determination by the optical finder cannot be suddenly performed.

  FIG. 14 shows an example of warning display. A substantially circular warning column D2 simulating a point light source is provided on the right side of the display column D1 in FIG. 14, and the point light source portion of the warning column D2 is lit (or flashes), thereby causing the above-described case. Can be displayed.

  Note that it is difficult for the operator to visually recognize the rear monitor 12 during the composition determination operation by the optical viewfinder of FIG. For this reason, it is preferable to provide a warning indicator lamp or the like around the viewing area of the subject image by the optical finder so that a separate warning display can be viewed through the finder window 10. Alternatively, “warning” may be performed by voice output instead of display.

  In the imaging apparatus 1A, when an automatic focusing operation (AF operation) using both the phase difference AF method and the contrast AF method is executed, both the state of FIG. 4 and the state of FIG. 5 are sequentially performed. To be realized. Therefore, regardless of whether the current state is the state of FIG. 4 or the state of FIG. 5, a period in which only one composition can be determined occurs. Therefore, in this embodiment, the above warning is issued even when the combined method is determined as the optimum AF method.

<AF driving operation and photographing operation>
Thereafter, when it is determined in step SP17 that the release button 11 is half-pressed S1, an AF driving operation (step SP18) for actually driving the photographing lens is executed.

  This AF driving operation is executed according to the AF method determined in step SP12 as the AF method to be actually used. For example, when the phase difference AF is selected in step SP12, an AF driving operation based on the phase difference AF is executed in step SP18 (see FIG. 4). When contrast AF is selected in step SP12, an AF driving operation by contrast AF is executed in step SP18 (see FIG. 5). When the combined method is selected in step SP12, an AF driving operation using the combined method is executed in step SP18.

  As described above, since the AF driving operation for driving the focus lens is realized by the optimum AF method according to the shooting situation of the subject, the AF method can be appropriately switched.

  Thereafter, until it is determined in step SP19 that the release button 11 has been fully pressed S2, the process returns to step SP11 and the operations in steps SP11 to SP18 are repeated. On the other hand, if it is determined in step SP19 that the release button 11 has been fully pressed S2, the process proceeds to step SP20, and in the state of FIG. 5, a main photographing operation with an exposure operation is performed.

<1-5. Judgment process>
<Branch processing according to AF method>
Next, the determination process in step SP11 will be described with reference to the detailed flowchart of FIG. According to this determination processing, the optimum AF method is determined according to the current shooting situation of the subject. As described above, the determination result of this determination process is used for “recommendation display” (step SP14), warning operation (step SP16), and AF drive operation (step SP18).

  First, in steps SP21 and SP22, it is determined whether phase difference AF is possible or contrast AF is possible.

  As described above, in the imaging apparatus 1A, whether to use an optical finder or a live view display is set as a main composition determination operation by an operator's setting operation. Then, until the release button 11 is half-pressed, the composition determining operation corresponding to the set content is performed.

  When it is set that composition determination is performed using the optical finder, as shown in FIG. 4, determination processing of the in-focus lens position by the phase difference detection method using the AF module 20 is possible. In short, the phase difference AF is possible. However, in the state shown in FIG. 4 (mirror down state), light from the subject does not enter the image sensor 5, so that the process of determining the focus lens position by the contrast method using the subject light incident on the image sensor 5 can be unexpected. It is. In short, contrast AF is impossible.

  On the other hand, when it is set to determine the composition using the live view display, as shown in FIG. 5, the determination process of the focusing lens position by the contrast method using the subject light incident on the image sensor 5 is performed. Is possible. In short, contrast AF is possible. However, in the state of FIG. 5 (mirror-up state), since light from the subject does not enter the AF module 20, determination processing of the focusing lens position by the phase difference detection method using the AF module 20 is impossible. In short, the phase difference AF is impossible.

  If the imaging apparatus 1A has the state shown in FIG. 4 (for example, when setting the composition using the optical viewfinder is set), it is determined in step SP21 that the phase difference AF is possible. Then, the process proceeds to step SP30.

  On the other hand, when the imaging apparatus 1A has the state of FIG. 5 (when setting to perform composition using live view display is set), it is determined in step SP22 that contrast AF is possible. The process proceeds to step SP40.

  Incidentally, during the transition between the states of FIG. 4 and FIG. 5, there is a period in which neither phase difference AF nor contrast AF is possible although it is a very short time. In this minute period, it is determined that “AF is not possible” (step SP23) and exception processing is performed. For example, when it is determined that “AF is not possible”, the following recommendation display and warning display may not be performed.

  In the imaging apparatus 1A, the AF method determined in step SP12 is adopted after the release button 11 is half-pressed S1 in the automatic switching mode MD3. When the phase difference AF is adopted, the imaging apparatus 1A is changed to the state shown in FIG. 4, and when the contrast AF is adopted, the imaging apparatus 1A is changed to the state shown in FIG. The action is executed. Therefore, during the period when the release button 11 is in the half-pressed state S1, whether to proceed to step SP30 or to proceed to step SP40 is determined according to the AF method determined in step SP12.

  Here, after the half-pressed state S1 of the release button 11 is released, the main composition determining operation determined by the operator's setting operation is resumed, and the state after the return is the state shown in FIG. Whether to proceed to step SP30 or to step SP40 is determined depending on whether it is the state of FIG.

<Step SP30>
Next, the detailed operation of step SP30 will be described with reference to FIG.

  This step SP30 is executed when the imaging apparatus 1A has the state shown in FIG. The determination unit 123 determines the shooting state of the subject using detection information from sensors (specifically, the AF module 20 and the photometric sensor 40) that can be used in the state, and an optimum AF method according to the shooting state. To decide.

  First, in step SP31, whether or not the condition C1 that the amount of light received by the AF module 20 is smaller than the predetermined threshold TH1 and the amount of light received by the photometric sensor 40 is smaller than the predetermined threshold TH2 is satisfied. judge. If the condition C1 is satisfied, it is determined that the shooting state of the subject is very dark, and the process proceeds to step SP36 to determine the phase difference AF method as the optimum AF method. According to this, when the subject is dark, it is possible to determine the phase difference AF method that is relatively strong against an insufficient amount of light as the optimum AF method. In particular, when the AF module 20 and the photometric sensor 40 receive light from a plurality of different portions of the subject, the contrast AF method is used by determining using the brightness of the plurality of different portions. It is possible to more accurately determine whether or not the focusing operation is difficult due to insufficient brightness. On the other hand, if the condition is not satisfied, the process proceeds to step SP32.

  In step SP32, it is determined whether or not a condition C2 that there are a plurality of in-focus lens positions detected by the phase difference detection signal of the AF module 20 is satisfied. For example, when the phase difference AF method is used for a lattice-like object, the focusing lens position cannot be appropriately specified due to the influence of the adjacent grating portion due to the principle of the phase difference AF method. As a result, a plurality of candidate positions may remain coexisting. Therefore, when the condition C2 is satisfied, it is determined that such a situation has occurred, and the process proceeds to step SP37 to determine the contrast AF method as the optimum AF method. According to the contrast AF method, the focus lens position can be specified more accurately than in the phase difference AF method. According to this, the contrast AF is determined as the optimum AF method when the gradation value of the subject changes periodically at a high frequency (spatial frequency), such as when the subject has a lattice shape. be able to. On the other hand, when the condition C2 is not satisfied, the process proceeds to step SP33.

  In step SP33, it is determined whether or not a condition C3 that the defocus amount DF is larger than a predetermined threshold value TH3 is satisfied. Specifically, the difference (shift) between the lens position specified as the in-focus lens position by the phase difference AF method using the AF module 20 and the current lens position of the photographing lens is calculated as the defocus amount DF. . Then, it is determined whether or not the defocus amount DF is larger than a predetermined threshold value TH3. When the condition C3 is satisfied, the process proceeds to step SP36 in consideration of the subject photographing condition that the defocus amount DF is relatively large, and a relatively high-speed phase difference AF method is determined as the optimum AF method. According to this, when the subject is relatively out of focus and the lens position is moved by a relatively large amount before reaching the in-focus state, a relatively high-speed phase difference AF method is used as the optimum AF. It is possible to determine the method and realize a high-speed AF operation. On the other hand, if the condition C3 is not satisfied, the process proceeds to step SP34.

  In step SP34, it is determined whether or not a condition C4 that the contrast of the subject image received by the AF module 20 is greater than a predetermined threshold TH4 is satisfied. If the condition C4 is satisfied, it is determined that the subject image by the AF module 20 is a relatively clear image and the focus lens position can be specified sufficiently even by the phase difference AF method, and the process proceeds to step SP36. A relatively high-speed phase difference AF method is determined as the optimum AF method. On the other hand, if the condition C4 is not satisfied, the process proceeds to step SP35.

  In step SP35, it is determined whether or not the condition C5 that the contrast of the subject image received by the AF module 20 is smaller than the predetermined threshold TH5 (<TH4) (low contrast) is satisfied. When the condition C5 is satisfied, it is determined that the subject lens image by the AF module 20 is unclear, so that it is impossible to specify the in-focus lens position by the phase difference AF method, and the process proceeds to step SP37 for higher accuracy. The contrast AF method is determined as the optimum AF method. On the other hand, if the condition C5 is not satisfied, the process proceeds to step SP38.

  The process proceeds to step SP38 to the extent that the subject image by the AF module 20 is not so blurred that the phase difference AF method cannot be used, but the focus determination can be sufficiently performed only by the phase difference AF method. Is determined to be not clear. That is, this is a case where the sharpness of the subject image by the AF module 20 is medium.

  In step SP38, it is determined that this is the case, and the “combination method” is determined as the optimum AF method.

  When the “combined method” is adopted in the AF driving operation of step SP18, for example, the phase difference AF method is first employed to obtain the focus lens position and the photographing lens is moved to the vicinity of the focus lens position. Then, the operation of moving the focus lens is performed using the contrast AF method.

  Specifically, after the focus lens is moved to a position slightly before the focusing lens position by the phase difference AF method in the state of FIG. 4, the arrangement of the mirror mechanism 6 is changed to the state of FIG. Then, while continuously moving the focus lens, an evaluation value for contrast AF at each lens position is obtained, and a lens position (peak lens position) corresponding to the peak of the change curve of the evaluation value for contrast AF is finally determined. The focus lens position is determined, and the focus lens is moved to the peak lens position. In this way, a more efficient AF operation is performed by moving the photographing lens to the vicinity of the original in-focus lens position with relatively high-speed phase difference AF and finely adjusting the lens position with contrast AF. It is possible.

  Further, when the AF mode is set to the automatic switching mode MD3, when it is determined in step SP30 that the “phase difference AF method” is the optimum AF method (step SP36), in the AF driving operation of step SP18. However, the state of the mirror mechanism 6 does not need to be changed, and thus the composition determination method does not need to be changed. On the other hand, when it is determined in step SP30 that the “contrast AF method” or the “combination method” is the optimum AF method (SP37, SP38), the state shown in FIG. 4 is changed from the state shown in FIG. 5 to the state shown in FIG. Therefore, the state of the mirror mechanism 6 is also changed, and the composition determination method is also changed. According to the warning operation as described above, such a state change can be predicted.

<Step SP40>
Next, the detailed operation of step SP40 will be described with reference to FIG.

  This step SP40 is executed when the imaging apparatus 1A has the state shown in FIG. The determination unit 123 determines the shooting state of the subject using detection information from a sensor (specifically, the image sensor 5) that can be used in the state, and determines an optimum AF method according to the shooting state.

  First, in step SP41, it is determined whether or not a condition C6 that the amount of light received by the image sensor 5 is smaller than a predetermined threshold value TH6 is satisfied. If the condition C6 is satisfied, it is determined that the shooting state of the subject is very dark, and the process proceeds to step SP36 to determine the phase difference AF method as the optimum AF method. According to this, when the subject is dark, it is possible to determine the phase difference AF method that is relatively strong against an insufficient amount of light as the optimum AF method. On the other hand, if the condition C6 is not satisfied, the process proceeds to step SP42.

  In step SP42, contrast information obtained by a difference filter of two types of spatial frequencies is acquired for one captured image (subject image) acquired at a certain time by the image sensor 5. Then, the degree of focus of the subject is detected by using the comparison result between the contrast information (high-frequency contrast component) by the high-frequency difference filter FA and the contrast information (low-frequency contrast component) by the low-frequency difference filter FB, and the focus degree is predetermined. Determine whether it is greater than the level. This determination method will be described later.

  When the condition C7 that the degree of focus is determined to be greater than the predetermined level based on the comparison result is satisfied, the process proceeds to step SP37, and the contrast AF method is determined as the optimum AF method. According to the contrast AF method, it is possible to move the photographing lens to a more accurate focusing lens position.

  On the other hand, when the condition C7 is not satisfied, the process proceeds to step SP43, and the phase difference AF method is adopted in principle. Therefore, when the degree of focus is smaller than a predetermined level, in principle, a relatively high-speed phase difference AF method is determined as the optimum AF method.

  In step SP43, it is determined whether or not a condition C8 that the contrast of the subject image received by the image sensor 5 is smaller than a predetermined threshold TH8 (low contrast) is satisfied.

  When the condition C7 is not satisfied and the condition C8 is not satisfied, the process proceeds to step SP38, and the combined method using not only the phase difference AF method but also the contrast AF method is determined as the optimum AF method.

  On the other hand, when the condition C7 is not satisfied but the condition C8 is satisfied, the subject image by the image sensor 5 is unclear, and therefore it is not possible to specify the focus lens position in the contrast AF method using the image captured by the image sensor 5. If it is determined that it is possible, the process proceeds to step SP36 to determine the phase difference AF method as the optimum AF method.

  When the AF mode is set to the automatic switching mode MD3 and the “contrast AF method” is determined to be the optimum AF method in step SP40 (step SP37), the AF driving operation in step SP18 is also performed. It is not necessary to change the state of the mirror mechanism 6 and, in turn, it is not necessary to change the composition determination method. On the other hand, when it is determined in step SP40 that the “phase difference AF method” or the “combination method” is the optimum AF method (SP36, SP38), in the AF driving operation of step SP18, the state shown in FIG. The state of the mirror mechanism 6 is also changed to the state, and the composition determination method is also changed. According to the warning operation as described above, such a state change can be predicted.

<Focus determination operation based on different contrast information>
Here, a method (step SP42) for determining the degree of focus using two types of contrast information (low frequency component and high frequency component) acquired from one photographed image will be described.

  FIG. 17 is a flowchart showing the detailed operation (step SP70) of this determination method. FIG. 18 is a diagram showing a table showing numerical examples, and FIG. 19 is a diagram showing a graph related to the numerical examples. FIG. 20 is a diagram illustrating the relationship between the high-frequency contrast component and the low-frequency contrast component according to the degree of focus.

  As shown in FIG. 17, when the captured image G is acquired (step SP71), the captured image G is filtered by a relatively high-frequency differential filter (also referred to as a high-frequency filter) FA to acquire data DA ( Along with step SP72), the captured image G is subjected to a filtering process using a relatively low frequency differential filter (also referred to as a low frequency filter) FB to obtain a data DB (step SP73). Then, a ratio RC between the maximum value in the data DA and the maximum value in the data DB is obtained (step SP74).

  When the ratio RC is smaller than the threshold value THe and the condition that the representative value (for example, the maximum value) of the data DA is larger than the threshold value THd, the degree of focusing is larger than a predetermined level (in short, the matching value). It is determined that it is near the focal point (steps SP75, SP76, SP77). On the other hand, when the condition is not satisfied, it is determined that the degree of focus is lower than a predetermined level (in short, not near the focus) (step SP78).

  FIG. 18 is a numerical example showing the state of the image at each of the three lens positions. Here, for simplification, a one-dimensional pixel array is shown.

  In the leftmost column L1 in FIG. 18, numerical examples indicating “in-focus state” are shown. In the middle column L2, numerical examples indicating a slightly blurred state (“slightly blurred state”) are shown, and the rightmost column L3 indicates a further blurred state (“blurred state”). Numerical examples are shown.

  For example, in the leftmost column of the column L1, the pixel values (gradation values) from the first pixel position to the fifteenth pixel position change to 30, 45, 68,. The state of doing is shown. In the graph of FIG. 19, the pixel arrangement in the focused state is shown as a curve LC1. Further, data DA obtained by subjecting this pixel arrangement to the filtering process by the high frequency filter FA (1, 0, −1) is shown in the center column of the column L1 in FIG. Is shown as curve LH1. Further, the data DB obtained by subjecting the pixel arrangement of the curve LC1 to the filter processing by the low-frequency filter FB (1, 0, 0, 0, −1) is the rightmost column of the column L1 in FIG. And is shown as curve LL1 in FIG. Also, the ratio RC (value 1.44) between the maximum value of data DA (specifically 285) and the maximum value of data DB (specifically 411) in this in-focus state is the column L1 in FIG. It is shown in the second row from the bottom.

  Similarly, in the leftmost column of the column L2, pixel values (gradation values) from the first pixel position to the fifteenth pixel position are shown. In the graph of FIG. 19, the pixel arrangement in a “slightly blurred state” is shown as a curve LC2. Further, the data DA obtained by subjecting this pixel arrangement to the filtering process by the high frequency filter FA is shown in the center column of the column L2 in FIG. 18 and also as the curve LH2 in FIG. . Further, the data DB obtained by applying the filter processing by the low-frequency filter FB to the pixel arrangement of the curve LC2 is shown in the rightmost column of the column L2 in FIG. 18, and as the curve LL2 in FIG. It is shown. Further, the ratio RC (value 1.51) between the maximum value of data DA (specifically 129) and the maximum value of data DB (specifically 195) in this “slightly blurred state” is shown in FIG. It is shown in the second line from the bottom of the column L2.

  In the leftmost column of the column L3, pixel values (gradation values) from the first pixel position to the fifteenth pixel position are shown. In the graph of FIG. 19, the pixel arrangement in the “blurred state” is shown as a curve LC3. Further, the data DA obtained by subjecting this pixel arrangement to the filtering process by the high frequency filter FA is shown in the center column of the column L3 in FIG. 18 and also as the curve LH3 in FIG. . Further, the data DB obtained by performing the filtering process with the low-frequency filter FB on the pixel arrangement of the curve LC3 is shown in the rightmost column of the column L3 in FIG. 18, and as the curve LL3 in FIG. It is shown. The ratio RC (value 1.60) between the maximum value of data DA (specifically 51) and the maximum value of data DB (specifically 82) in this “blurred state” is the column L3 in FIG. Is shown in the second row from the bottom.

  FIG. 20 is a conceptual diagram showing how data DA and data DB change as the lens position changes. As shown in FIG. 20, when the lens position is in the vicinity of the focusing lens position XP, the data DA and the data DB are relatively close to each other, whereas the lens position moves away from the focusing lens position XP. As a result, the difference between the data DA and the data DB increases. For this reason, the ratio between the high frequency contrast component and the low frequency contrast component increases as the lens position deviates from the focusing lens position XP. For example, if the maximum value is adopted as the representative value of the two frequency contrast components, for example, the ratio RC (= MB / MA) between the maximum value MA of the high frequency contrast component and the maximum value MB of the low frequency contrast component matches the lens position. It becomes larger as it deviates from the focal lens position XP. Also in FIG. 18, the ratio RC is 1.44 in the focused state, but gradually increases to 1.51 and 1.60 as the degree of focusing decreases. It is shown.

  Therefore, here, using the principle as described above, when the ratio RC is smaller than a predetermined threshold value THe (for example, 1.50), it is determined that the degree of focusing is larger than a predetermined level.

  Further, here, the condition that the representative value (here, the maximum value) of the data DA is larger than the threshold value THd is also considered. According to this, it can be confirmed that the captured image has a relatively high contrast. Although FIG. 20 shows the case where the threshold value THd is a variable value, a fixed value may be adopted as the threshold value THd.

  In the above, the case where the maximum value is adopted as the representative value of each frequency contrast component is exemplified, but the present invention is not limited to this, and the total value of each frequency contrast may be adopted as the representative value. Good. At the bottom of FIG. 18, the ratio RD between the total value of the data DA and the total value of the data DB is shown for each state. When the ratio RD is smaller than a predetermined threshold value THe (for example, 1.57), it may be determined that the in-focus state is achieved.

<2. Second Embodiment>
<2-1. Configuration>
In the first embodiment, the image pickup apparatus 1A having a configuration in which the phase difference AF and the contrast AF cannot be performed simultaneously is exemplified. In the second embodiment, an imaging apparatus 1B having a configuration capable of simultaneously executing phase difference AF and contrast AF is illustrated. Below, it demonstrates centering on difference with 1st Embodiment.

  FIG. 21 is a cross-sectional view illustrating a schematic configuration of the imaging apparatus 1B according to the second embodiment, and FIG. 22 is a block diagram illustrating a functional configuration of the imaging apparatus 1B.

  As shown in FIGS. 21 and 22, the imaging apparatus 1B further includes an imaging element (sub-image sensor) 7 in a part of the finder optical system. This image sensor 7 is an image sensor provided separately from the image sensor 5 which is a main image sensor. By using the image captured by the image sensor 7, live view display and contrast AF can be realized.

  The imaging apparatus 1B is in a state as shown in FIG. 21 during the period until the release button 11 is fully pressed, that is, during the composition determination operation. Specifically, as in FIG. 4, the main mirror 61 is disposed on the optical path (imaging optical path) from the imaging lens unit 3 to the image sensor 5, and the reflected light from the main mirror 61 is traveled by the pentamirror 65. Is further changed to reach the finder window 10. Therefore, the composition determination operation by the optical finder is possible.

  Further, the imaging device 1B includes an optical element (half mirror) 68 on the optical path from the pentamirror 65 toward the finder window 10. The reflected light from the main mirror 61 is changed in its traveling direction by the pentamirror 65, and then the optical path of a part of the light is changed by the optical element 68 and travels in a direction different from that of the finder window 10. (Half mirror) 69 is transmitted and reaches the image sensor 7. A part of the light reaching the optical element 69 is reflected by the optical element 69 and reaches the photometric sensor 40.

  The image sensor 7 has the same configuration as the image sensor 5 and is used for generating an image signal (moving image) for live view. However, the image sensor 7 does not need to have the same number of pixels as the image sensor 5, and may be configured with a smaller number of pixels than the image sensor 5.

  The same signal processing as that of the image signal acquired by the image sensor 5 is performed on the image signal acquired by the image sensor 7. That is, the image signal acquired by the image sensor 7 is converted into digital data by the A / D conversion circuit 52, subjected to predetermined image processing by the digital signal processing circuit 50, and stored in the image memory 56.

  Time-series captured images stored in the image memory 56 are sequentially read out from the image memory 56 and displayed sequentially on the rear monitor 12. As a result, a moving image display (live view display) is realized. That is, a composition determination operation by live view display is possible.

  Further, by obtaining an evaluation value related to contrast for each of a plurality of captured images by the image sensor 7, a focusing lens position specifying operation for obtaining a lens position for optimizing the evaluation value as a focusing lens position, and the focusing lens An AF driving operation for moving the focus lens to a position is realized. That is, the imaging apparatus 1B can perform contrast AF by using a captured image acquired by the imaging element 7.

  Further, the light transmitted through the main mirror 61 is reflected downward by the sub-mirror 62 and guided to the AF module 20 to be incident thereon. The AF module 20 generates a phase difference detection signal using incident light. By using this phase difference detection signal, an in-focus lens position specifying operation for obtaining the in-focus lens position and an AF drive operation for moving the focus lens to the in-focus lens position are realized. That is, the imaging apparatus 1B can perform the phase difference AF by using the phase difference detection signal acquired by the AF module 20.

  As described above, during the period until the release button 11 is half-pressed S2, the composition determination operation by the live view display and the composition determination operation by the optical viewfinder can be realized at the same time. Further, it is possible to adopt both the phase difference AF method and the contrast AF method during the synchronization.

  When the release button 11 is fully pressed S2, the mirror mechanism 6 is arranged so as to be in the mirror-up state as in FIG. 5, and the exposure operation by the image sensor 5 is possible. The image sensor 5 photoelectrically converts the subject image received in accordance with the opening timing of the shutter 4 to generate an image signal of the subject. In this way, a main photographic image (photographed image data) relating to the subject is obtained.

<2-2. Operation>
FIG. 23 and FIG. 24 are flowcharts showing the operation in the imaging apparatus 1B. FIG. 23 is a flowchart showing the overall operation, and FIG. 24 is a flowchart showing the detailed operation of a part (step SP80).

  The operation in FIG. 23 is the same as that in the first embodiment (see FIG. 6), but the process in step SP80 is executed instead of the process in step SP11, and the processes in steps SP15 and SP16 are not executed. This is different from the operation of the first embodiment.

  Since the imaging apparatus 1B has the above-described configuration, it is not necessary to change the composition determination operation method even when the AF method is switched. Therefore, in the second embodiment, as shown in FIG. 23, the warning operation (steps SP15 and SP16) is not performed.

  Further, in the imaging apparatus 1B of the second embodiment, the contrast evaluation value relating to the phase difference detection signal and the captured image by the AF module 20 regardless of which of the two types of composition determination methods described above is adopted. It is possible to use both. Therefore, in the second embodiment, the process of step SP80 (different from the process of step SP11) is adopted as the determination process for determining the optimum AF method.

  Hereinafter, the process of step SP80 will be described with reference to FIG. Note that the processing in step SP80 is basically based on the concept of preferentially adopting the phase difference AF method. In the contrast AF method, the lens needs to move over the range before and after the position of the focusing lens, so that the subject image becomes very clear once and then becomes very clear again. Operation (in short, going back and forth) is performed. In contrast, in the phase difference AF method, such a return operation is not performed. Accordingly, the phase difference AF method is less uncomfortable for the operator. Further, the phase difference AF method has an advantage that it is faster than the contrast AF method.

  Step SP81 is the same processing as step SP31, but differs in that in addition to the amount of light received by the AF module 20 and the amount of light received by the photometric sensor 40, the amount of light received by the image sensor 7 is also considered. Specifically, the amount of light received by the AF module 20 is smaller than a predetermined threshold TH1, the amount of light received by the photometric sensor 40 is smaller than a predetermined threshold TH2, and the amount of received light by the image sensor 7 is predetermined. It is determined whether or not the condition C11 is smaller than the threshold value TH11. If the condition C11 is satisfied, it is determined that the shooting state of the subject is very dark, and the process proceeds to step SP88 to determine the phase difference AF method as the optimum AF method. On the other hand, if the condition C11 is not satisfied, the process proceeds to step SP82.

  In step SP82, processing similar to that in step SP32 is performed. When the above-mentioned condition C2 that there are a plurality of in-focus lens positions detected by the phase difference detection signal of the AF module 20 is satisfied, the process proceeds to step SP89 and the contrast AF method is determined as the optimum AF method. According to the contrast AF method, the focus lens position can be specified more accurately than in the phase difference AF method. On the other hand, when the condition C2 is not satisfied, the process proceeds to step SP33.

  In step SP83, the same processing as in step SP33 is performed. It is determined whether or not the condition C3 that the defocus amount DF is larger than a predetermined threshold value TH3 is satisfied.

  If the condition C3 is satisfied, the process proceeds to step SP88, and a relatively high-speed phase difference AF method is determined as the optimum AF method. According to this, when the subject is out of focus relatively, it is possible to determine a relatively high-speed phase difference AF method as the optimum AF method and realize a high-speed AF operation.

  On the other hand, if the condition C3 is not satisfied, the process proceeds to step SP84.

  In step SP84, determination processing considering two conditions is performed.

  First, as one condition, it is determined whether or not the condition C12 that the defocus amount DF is smaller than a predetermined threshold TH12 (<TH3) is satisfied. As described above, the defocus amount DF is calculated as the difference (deviation) between the lens position specified as the in-focus lens position by the phase difference AF method using the AF module 20 and the current lens position of the photographing lens. The This condition C12 is also expressed as a condition for determining the in-focus state by the phase difference AF method. The threshold value TH12 may be the same value as the threshold value TH3.

  Further, as another condition, it is determined whether or not a condition C13 that the degree of focus is determined to be smaller than a predetermined level based on the contrast information by the two types of spatial frequency filters FA and FB described above is determined. The The condition C13 is also expressed as a condition for performing an in-focus determination operation for determining whether the in-focus state or the in-focus state using different types (here, two types) of contrast information. The

  Then, it is determined whether or not a condition C14 that satisfies both the condition C12 and the condition C13 is satisfied. When the condition C14 is satisfied, the process proceeds to step SP89, and the contrast AF method is determined as the optimum AF method. In the case where the condition C14 is satisfied, specifically, the defocus amount DF based on the phase difference detection result by the AF module 20 is smaller than the threshold value TH12, and each contrast by the two types of spatial frequency filters FA and FB is used. This is a case where the degree of focus is determined to be smaller than a predetermined level based on the information. In short, it is also expressed as a case where the in-focus state is determined by the phase-difference AF method and the in-focus state is determined by the in-focus determination operation based on the different kinds of contrast information.

  By considering the condition C12, it is possible to reduce the frequency of adopting the contrast AF method (in other words, increase the frequency of use of the phase difference AF method). For example, when it is determined that the defocus amount DF calculated by the phase difference AF method is larger than the threshold value TH12 and in an out-of-focus state, the phase difference AF is adopted in principle in the determinations of steps SP84 to SP87. Because it becomes.

  Further, the frequency of adopting the contrast AF method can be further reduced by further considering the condition C13. When it is determined that the in-focus state is obtained by the in-focus determination operation based on the different-type contrast information, it is sufficiently within the in-focus range, so that it is less necessary to perform the AF operation by the contrast AF method. Therefore, as an optimum AF method, processing is advanced in a direction in which the phase difference AF method is adopted in principle rather than the contrast AF method. On the other hand, if it is determined that the in-focus state is determined by the in-focus determination operation based on the different contrast information, an attempt is made to improve the in-focus level by using a contrast AF method that is more accurate than the phase difference AF method. Can do.

  On the other hand, if the condition C14 is not satisfied, the process proceeds to step SP85.

  Step SP85 is the same processing as step SP34. Specifically, it is determined whether or not the condition C4 that the contrast of the subject image received by the AF module 20 is larger than a predetermined threshold TH4 is satisfied. If the condition C4 is satisfied, the process proceeds to step SP88, and the phase difference AF method is determined as the optimum AF method. On the other hand, if the condition C4 is not satisfied, the process proceeds to step SP86.

  Step SP86 is the same processing as step SP43. Specifically, in step SP86, it is determined whether or not the condition C16 that the contrast of the subject image received by the image sensor 7 is smaller than a predetermined threshold TH16 (low contrast) is satisfied. When the condition C16 is satisfied, the subject image by the image sensor 7 is unclear, so it is determined that the focus lens position cannot be specified by the contrast AF method using the photographed image by the image sensor 7, Proceeding to step SP88, the phase difference AF method is determined as the optimum AF method. On the other hand, if the condition C16 is not satisfied, the process proceeds to step SP87.

  Step SP87 is the same processing as step SP35. Specifically, in step SP87, it is determined whether or not the condition C5 that the contrast of the subject image received by the AF module 20 is smaller than the predetermined threshold TH5 (<TH4) (low contrast) is satisfied. . When the condition C5 is satisfied, it is determined that it is impossible to specify the focus lens position by the phase difference AF method because the subject image by the AF module 20 is unclear, and the process proceeds to step SP89 for higher accuracy. The contrast AF method is determined as the optimum AF method. On the other hand, if the condition C5 is not satisfied, the process proceeds to step SP90.

  In step SP90, a combined method using not only the phase difference AF method but also the contrast AF method is determined as the optimum AF method. As the “combination method” determined in step SP90, the same mode as the “combination method” determined in step SP38 can be used. In the above-described step SP38, the combined method in the case where the phase difference AF and the contrast AF cannot be executed at the same time has been described. However, the present invention is not limited to this. Can be executed simultaneously, the following combination method is also possible.

  Specifically, the focus lens is moved toward the focus lens position specified by the phase difference AF, and an evaluation value for contrast AF at each lens position is also acquired during the movement. Then, the lens position corresponding to the peak of the change curve of the evaluation value for contrast AF is determined as the final focus lens position, and the focus lens is moved to the peak lens position. If the peak lens position corresponding to the peak of the evaluation value cannot be detected even after reaching the in-focus lens position specified by the phase difference AF, the contrast AF operation is continued. That is, the AF driving operation for detecting the peak lens position is performed by further performing the evaluation value calculation operation while moving the lens. On the other hand, when the peak lens position is detected before reaching the in-focus lens position specified by the phase difference AF, the AF driving operation is terminated by moving to the peak lens position. According to this, it is possible to complete the AF driving operation at a higher speed.

  You may make it perform AF operation | movement by such a combined method.

<3. Third Embodiment>
As in the second embodiment, the third embodiment exemplifies an imaging apparatus having a configuration capable of simultaneously executing phase difference AF and contrast AF. Below, it demonstrates centering on difference with 2nd Embodiment.

  FIG. 25 is a cross-sectional view illustrating a schematic configuration of an imaging apparatus 1C according to the third embodiment. In the imaging apparatus 1C, no optical finder is provided, and composition determination is performed using live view display.

  The imaging apparatus 1C is in a state as shown in FIG. 25 during the period until the release button 11 is fully pressed, that is, during the composition determination operation. Specifically, the main mirror 61 is disposed on the optical path (imaging optical path) from the photographic lens unit 3 to the image sensor 5, and the traveling direction of the reflected light from the main mirror 61 is further changed by the pentamirror 65, It reaches the image sensor 5. The image sensor 5 is disposed in parallel to the optical path (imaging optical path) from the photographing lens unit 3 to the image sensor 5 and is disposed so as to be perpendicular to the optical axis of the reflected light from the main mirror 61. ing.

  The imaging apparatus 1C can always obtain a photographed image by the imaging element 5 in the composition determination state. The image capturing apparatus 1C performs live view display using the image captured by the image sensor 5.

  Further, by obtaining an evaluation value related to contrast for each of a plurality of captured images by the image pickup device 5, a focusing lens position specifying operation for obtaining a lens position that optimizes the evaluation value as a focusing lens position is realized. Also, an AF driving operation for moving the focus lens to the focus lens position is realized. In other words, the imaging apparatus 1 </ b> C can perform contrast AF by using the captured image acquired by the imaging element 5.

  Further, the light transmitted through the main mirror 61 is reflected downward by the sub-mirror 62 and guided to the AF module 20 to be incident thereon. The AF module 20 generates a phase difference detection signal using incident light. By using this phase difference detection signal, an in-focus lens position specifying operation for obtaining the in-focus lens position and an AF drive operation for moving the focus lens to the in-focus lens position are realized. That is, the imaging apparatus 1B can perform the phase difference AF by using the phase difference detection signal acquired by the AF module 20. An optical element (half mirror) 72 is provided between the sub mirror 62 and the AF module 20, and a part of the light reaching the optical element 72 is reflected by the optical element 72 and reaches the photometric sensor 40. To do. The photometric sensor 40 is not limited to this, and may receive a part of the light traveling from the main mirror 61 toward the image sensor 5.

  As described above, both AF methods of the phase difference AF method and the contrast AF method can be employed during the period until the release button 11 is fully pressed S2.

  When the release button 11 is fully pressed S2, the image sensor 5 photoelectrically converts the subject image received in accordance with the opening timing of the shutter 4 to generate an image signal of the subject. In this way, a main photographic image (photographed image data) relating to the subject is obtained.

  The operation of the imaging apparatus 1C according to the third embodiment is basically the same as that of the imaging apparatus 1B according to the second embodiment. However, the second embodiment is different from the second embodiment in that live view display and contrast AF are performed by using a captured image acquired by the image sensor 5 instead of using a captured image acquired by the image sensor 7.

  Even with such an imaging apparatus 1C, it is possible to obtain the same effect as the imaging apparatus 1B according to the second embodiment.

<4. Modification>
Although the embodiments of the present invention have been described above, the present invention is not limited to the contents described above.

  For example, in the first embodiment, the case where the lens group 37 of the photographing lens unit 3 is driven using the lens driving unit 38 provided on the photographing lens unit 3 side is illustrated, but the present invention is not limited to this. Specifically, as shown in FIG. 26, a mechanical drive unit (mechanical drive mechanism) 48 is provided on the main body side of the imaging apparatus 1 </ b> C, and the mechanical drive unit 48 is driven, whereby the lens in the photographic lens unit 3. The group 37 may be driven.

  In each of the above embodiments, when the automatic switching mode is selected as the AF mode, the determination unit 123 obtains the optimum AF method and then recommends the optimum AF method that is the determination result. In addition, the case where the optimum AF method is automatically adopted to perform the AF control operation is illustrated, but the present invention is not limited to this. For example, after the optimum AF method is obtained by the determination unit 123, the optimum AF method may be automatically adopted to perform the AF control operation without displaying the determination result as a recommendation. Alternatively, after determining the optimum AF method by the determination unit 123, the determination result may be simply displayed as a recommendation.

  In each of the above embodiments, the “phase difference AF method” and the “contrast AF method” that selectively use the phase difference detection signal from the AF module 20 and the evaluation value corresponding to the contrast are combined. Although the case where the optimum AF method is determined from the three AF methods of the “combined method” to be used is illustrated, the present invention is not limited to this. For example, an optimal AF method may be determined from two AF methods of “phase difference AF method” and “contrast AF method”. Alternatively, the optimum AF method may be determined from the two AF methods of “phase difference AF method” and “combination method”. Or, conversely, an optimal AF method may be determined from the two AF methods of “contrast AF method” and “combination method”.

It is a front external view of an imaging device. It is a back external view of an imaging device. It is a block diagram which shows the function structure of an imaging device. It is sectional drawing of an imaging device (at the time of OVF). It is sectional drawing of an imaging device (at the time of EVF). It is a flowchart which shows the whole operation | movement in an imaging device. It is a flowchart which shows detailed operation | movement of step SP11. It is a flowchart which shows detailed operation | movement of step SP30. It is a flowchart which shows detailed operation | movement of step SP40. It is a flowchart which shows detailed operation | movement of step SP12. It is a flowchart which shows detailed operation | movement of step SP14. It is a figure which shows the selection setting screen of AF mode. It is a figure which shows a recommendation display setting screen. It is a figure which shows the display screen containing a recommendation display and a warning display. It is a figure which shows the modification regarding recommendation display. It is a figure which shows the other modification regarding a recommendation display. It is a flowchart which shows the operation | movement which determines the focus degree based on the contrast of the image of 1 sheet. It is a figure which shows a numerical example. It is a figure which shows the graph regarding the numerical example of FIG. It is a figure which shows the relationship between a high frequency contrast component and a low frequency contrast component according to a focus degree. It is sectional drawing which shows the structure outline | summary of the imaging device which concerns on 2nd Embodiment. It is a block diagram which shows the function structure of an imaging device. It is a flowchart which shows the whole operation | movement in an imaging device. It is a flowchart which shows detailed operation | movement of step SP80. It is sectional drawing which shows the structure outline | summary of the imaging device which concerns on 3rd Embodiment. It is sectional drawing which shows the structure outline | summary of the imaging device which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A, 1B, 1C Image pick-up device 2 Camera main part 3 Shooting lens unit 5,7 Image pick-up element 6 Mirror mechanism 10 Finder window 11 Release button 12 Rear monitor 20 AF module 40 Photometric sensor 61 Main mirror 62 Sub mirror 65 Penta mirror 67 Eyepiece Lens 87 (AF mode) switch

Claims (3)

An image sensor that receives light from a subject on a predetermined imaging surface via an imaging lens, and photoelectrically converts the subject image to generate a captured image;
Phase difference detection means for receiving light from the subject and generating a phase difference detection signal corresponding to the degree of focus of the subject image;
Evaluation value calculation means for obtaining a predetermined evaluation value according to the contrast of the subject image based on the captured image;
An optimum AF method from among a plurality of AF methods that selectively or combinedly use the phase difference detection signal from the phase difference detection means and the predetermined evaluation value relating to the photographed image according to the shooting situation of the subject. Determining means for determining
Display means for displaying the determination result by the determination means before the AF operation;
An imaging apparatus comprising: a determination unit that determines an AF method used for an actual AF control operation from among the plurality of AF methods in response to an operation by an operator .   The determination means uses the predetermined evaluation value when it is determined that the degree of focus detected using the comparison result between the low-frequency contrast component and the high-frequency contrast component in the captured image is greater than a predetermined level. The imaging apparatus according to claim 1, wherein an AF method is determined as the optimum AF method.   The determination means uses the phase difference detection signal when it is determined that the degree of focus detected using the comparison result between the low-frequency contrast component and the high-frequency contrast component in the captured image is smaller than a predetermined level. The imaging apparatus according to claim 2, wherein an AF method is determined as the optimum AF method.

Images