JP2018142007A - Imaging device and control method thereof, program, and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable focus calibration for focus detection based on phase difference detection to be achieved simply and efficiently for even a general subject without using a dedicated chart.SOLUTION: The present invention comprises: an imaging unit for photoelectrically converting a subject image formed by a photographic optical system and generating an image signal; a phase difference detection unit for detecting, on the basis of a pair of image signals of the subject image, a first in-focus position of a focus lens included in the photographic optical system by means of phase difference detection; a contrast detection unit for detecting a second in-focus position of the focus lens by means of contrast detection using the image signal; a calibration unit for correcting the first in-focus position using a correction amount calculated from a difference between the second in-focus position and the first in-focus position; and a subject determination unit for determining whether or not the subject image is suitable for detection of the in-focus position by the phase difference detection unit or the contrast detection unit before or during the calibration performed by the calibration unit.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique for correcting a focus position obtained by a phase difference detection method based on a focus position detected by a contrast detection method.

  Conventionally, in an interchangeable lens type imaging device such as a single lens reflex camera, the focus state (defocus amount) of the photographing optical system is detected from the phase difference between a pair of images formed by light passing through the photographing optical system in the interchangeable lens. It is known to perform focus detection by a phase difference detection method. Such a phase difference detection method has a problem that the focus position may not be accurately detected due to the influence of the light source at the time of shooting, the color and type of the subject, and the like.

  In order to solve such a problem, Patent Document 1 includes a focus calibration function that corrects the in-focus position obtained by the phase difference detection method based on the in-focus position detected by the contrast detection method. A camera is disclosed. In the contrast detection method, a focus evaluation value indicating the contrast of a subject is obtained from a video signal generated using an image sensor in a digital camera, and the position of the focus lens that maximizes the focus evaluation value is set as a focus position. When detecting the position where the focus evaluation value is maximized, the change of the focus evaluation value is monitored while the focus lens is finely driven. In the digital camera disclosed in Patent Literature 1, the correction value obtained by the focus calibration is used to correct the focus position obtained by the phase difference detection method at the time of shooting, and the focus lens is moved to the corrected focus position. Thus, more accurate focusing control is performed.

  In Patent Document 2, in the focus calibration mode, a pseudo subject image generated in the camera is displayed on an external display device, and an in-focus position is obtained for each pseudo subject image by each detection method. And the camera which correct | amends the focus position of a phase difference detection system from the detection result is disclosed.

JP 2003-295047 A JP 2007-041095 A

  Here, in recent years, in the focus detection apparatus of the phase difference detection method, the focus detection area is expanded with respect to the shooting angle of view and the number of detection points is increased according to the user's request. Therefore, it is necessary to consider a focus calibration method according to the phase difference detection type focus detection device mounted on the imaging device.

  However, in the prior art disclosed in the above-mentioned Patent Document 1, there is no mention of a focus calibration method or a display method according to a difference in detection area or the number of detection points. In addition, it is only mentioned that it is desirable to use a dedicated chart rather than a general subject in order to perform focus calibration with high accuracy with respect to a subject used for in-focus position detection during calibration.

  Similarly, in the prior art disclosed in Patent Document 2, it is necessary to display a dedicated chart (pseudo subject image) on an external display device in order to perform focus calibration. Therefore, even if the user feels the necessity for focus calibration in the field, focus calibration cannot be performed without an external display device.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to make it possible to easily and efficiently perform focus calibration for focus detection by a phase difference detection method even on a general subject without using a dedicated chart. It is.

  An imaging apparatus according to the present invention includes an imaging unit that photoelectrically converts an object image formed by an imaging optical system to generate an image signal, and the imaging by a phase difference detection method based on a pair of image signals of the object image. A phase difference detection means for detecting a first focus position of a focus lens included in the optical system; and a contrast detection means for detecting a second focus position of the focus lens by a contrast detection method using the image signal. Calibration means for correcting the first focus position using a correction amount calculated from a difference between the second focus position and the first focus position; and calibration by the calibration means. Whether or not the subject image is suitable for detection of an in-focus position by the phase difference detection means or the contrast detection means before or during operation. Characterized in that it comprises a subject determination means for constant, the.

  According to the present invention, focus calibration for focus detection by the phase difference detection method can be easily and efficiently performed on a general subject without using a dedicated chart.

1 is a cross-sectional view illustrating a configuration of a digital single-lens reflex camera (mirror down state) according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a configuration of a digital single-lens reflex camera (mirror up / live view state) according to a first embodiment; 1 is a block diagram showing an electrical configuration of a digital single-lens reflex camera according to a first embodiment. 6 is a flowchart illustrating a focus calibration operation according to the first embodiment. 6 is a flowchart showing the operation of a focus calibration availability determination routine in the first embodiment. The figure which shows the display state of the liquid crystal monitor at the time of the live view in 1st Embodiment. The figure which shows the focus calibration availability determination result display in 1st Embodiment. 10 is a flowchart showing a focus calibration operation in the second embodiment. 9 is a flowchart showing the operation of a focus calibration availability determination routine in the second embodiment. The figure which shows the display state in the finder in 2nd Embodiment. The figure which shows the focus calibration availability determination result display in 2nd Embodiment. 10 is a flowchart showing a basic operation including an automatic focus calibration function in the third embodiment. 10 is a flowchart illustrating a focus calibration operation according to the third embodiment. 10 is a flowchart showing a focus calibration operation in the fourth embodiment. The figure which shows focus calibration availability range-finding point identification mode setting in 4th Embodiment. The figure which shows the data selection of the identification display setting of the focus calibration availability distance measuring point in 4th Embodiment. The figure which shows memory | storage of the focus calibration availability measurement point identification display setting in 4th Embodiment. The figure which shows the frequency setting of the focus calibration in the individual setting of the focus calibration availability distance measuring point identification display in the fourth embodiment. The figure which shows the ranging point display setting which can acquire the focus correction value in the focus calibration in the individual setting of the focusing point identification display of focus calibration in 4th Embodiment. FIG. 10 is a diagram illustrating distance measurement point display settings in which focus correction values cannot be acquired in focus calibration in individual settings of focus calibration availability distance measurement point identification display according to the fourth embodiment. FIG. 10 is a diagram showing focus point limit setting for focus correction value acquisition in focus calibration in individual setting of focus calibration enable / disable distance measuring point identification display in the fourth embodiment. The figure which shows the individual setting confirmation of the focus calibration availability measurement point identification display in 4th Embodiment. FIG. 10 is a diagram showing focus display at the first focus calibration subject and AF frame position in the fourth embodiment. The figure which shows the AF frame identification display of the focus calibration 1st result in 4th Embodiment. FIG. 14 is a diagram illustrating a focus calibration second subject, an AF frame position, and an AF frame display after a second focus calibration result in the fourth embodiment. FIG. 10 is a diagram illustrating an AF frame display after a focus calibration third-time subject, an AF frame position, and a third focus calibration result in the fourth embodiment. The figure which shows the display on a liquid crystal monitor after complete | finishing focus correction value memory | storage by the focus calibration of the to-be-photographed object, AF frame position, and all the ranging points in the 4th focus calibration in 4th Embodiment.

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

(First embodiment)
1 and 2 are diagrams showing a configuration of a digital single-lens reflex camera which is a first embodiment of an imaging apparatus of the present invention.

  1 and 2 show a main body 1 (hereinafter referred to as a camera main body) of a digital single-lens reflex camera. An interchangeable lens 3 is detachably mounted on the mount 2 fixed to the camera body 1. The mount 2 is provided with an interface unit (not shown) for communicating various signals with the interchangeable lens 3 and supplying power from the camera body 1 to the interchangeable lens 3.

  In the interchangeable lens 3, a photographing optical system including a focus lens (focus element) 3a, a variable power lens 3b, and a diaphragm 19 is accommodated. In the drawing, each lens is shown as being constituted by one lens, but it may be constituted by a plurality of lenses.

  In the camera body 1, the main mirror 4 constituted by a half mirror can be rotated between a down position shown in FIG. 2 and an up position shown in FIG. 3. When observing a subject image formed by the photographing optical system through a finder optical system to be described later (in the finder observation state), the main mirror 4 is in a down position that is disposed obliquely in the photographing optical path as shown in FIG. It is rotated. The main mirror 4 arranged at the down position reflects the light beam from the photographing optical system and guides it to the finder optical system. Further, at the time of shooting or during live view display (shooting / live view observation state), the main mirror 4 is rotated to the up position retracted from the shooting optical path as shown in FIG. As a result, the light beam from the photographing optical system is guided to the shutter 5 and the image sensor 6 described later.

  The shutter 5 controls exposure of the image sensor 6 with a light beam from the photographing optical system. The shutter 5 of the present embodiment is a focal plane shutter, and is configured to close in the viewfinder observation state and open in the shooting / live view observation state.

  The image sensor 6 is an image sensor composed of a CCD or CMOS image sensor and its peripheral circuits, and photoelectrically converts a subject image and outputs an image signal. Various processes are performed on the imaging signal in an image processing circuit 54 (see FIG. 3) described later, and an image signal is generated. The imaging signal is configured to be output independently for all pixels. Also, some pixels are focus detection pixels, and focus detection (imaging surface phase difference AF) using a phase difference detection method is possible on the imaging surface. More specifically, the imaging device 6 has a plurality of imaging pixels that each receive a light beam passing through the entire exit pupil of the interchangeable lens 3 that forms an image of the subject to generate an image of the subject. Furthermore, the imaging device 6 also has a plurality of focus detection pixels that each receive a light beam that passes through a partial region of the exit pupil of the interchangeable lens 3. The plurality of focus detection pixels as a whole can receive a light beam passing through the entire exit pupil of the interchangeable lens 3. The focus detection pixels are discretely arranged in the effective pixels in order to perform the imaging surface phase difference AF in the entire area of the imaging element 6. Details of the imaging surface phase difference AF are described in Japanese Patent Application Laid-Open No. 2009-244429, Japanese Patent Application Laid-Open No. 2010-117680, and the like, and thus detailed description thereof is omitted.

  The sub mirror 7 that rotates together with the main mirror 4 reflects the light beam that has passed through the main mirror 4 when the main mirror 4 is disposed at the down position, and guides it to the AF unit 8 described later. The sub mirror 7 rotates to the up position together with the main mirror 4 in the photographing / live view observation state.

  The AF unit 8 includes a field lens 8a disposed in the vicinity of the imaging surface, a reflection mirror 8b, a secondary imaging lens 8c, and an area sensor 8d including a plurality of light receiving elements disposed in a two-dimensional direction. Has been. The secondary imaging lens 8c forms a pair of subject images from the light flux incident from the photographing optical system and reflected by the main mirror 4, the sub mirror 7, and the reflection mirror 8b. The area sensor 8d photoelectrically converts the pair of subject images to generate a pair of image signals. These pair of image signals are output to a focus detection circuit 36 (see FIG. 3) described later. By using this image signal, it is possible to detect the focus state of the photographing optical system by the phase difference detection method (that is, focus detection). The secondary imaging lens 8b is configured to form a pair of subject images for each of the subjects included in a plurality of regions in the shooting screen. That is, a plurality of focus detection points (so-called distance measuring points) are arranged in the shooting screen. In this embodiment, 61 distance measuring points are arranged (see FIG. 7).

  A subject image is formed on the focusing plate 9 by the light beam reflected by the main mirror 4. The pentaprism 10 inverts the subject image formed on the exit surface of the focusing plate 9 into an erect image. The eyepiece 11 guides the light flux from the pentaprism 10 to the user's eyes and allows the user to observe the subject image on the focusing screen 9. An optical system composed of the focus plate 9, the pentaprism 10, and the eyepiece lens 11 is referred to as a finder optical system.

  A display device 12 composed of a polymer-dispersed liquid crystal panel (so-called PN liquid crystal panel) disposed in the vicinity of the focus plate 9 in the finder optical system displays various information such as the 61 distance measuring points described above in the finder. doing.

  The RGB photometric sensor 13 composed of an image sensor such as a CMOS sensor or a CCD has a configuration with a photometric optical system (not shown), and uses the photometric signal to measure the luminance of the subject image on the focusing screen 9 (so-called AE) and measure the color. It is possible to perform face detection by generating an image from a color or an imaging signal.

  A liquid crystal monitor 14 provided outside the camera body displays image signals (live view images and captured images) and various types of information.

  In the interchangeable lens 3, the focus motor 15 serves as a drive source for moving the focus lens 3a in the optical axis direction. The lead screw 16 is rotated by the focus motor 15. The lead screw 16 meshes with a rack attached to the focus lens 3a (actually attached to a holding frame that holds the focus lens 3a). For this reason, when the lead screw 16 is rotated by the focus motor 15, the focus lens 3a moves in the optical axis direction due to the engagement of the lead screw 16 and the rack.

  A pulse plate 17 is attached to the tip of the lead screw 16 so as to be rotatable integrally with the lead screw 16. In the interchangeable lens 3, a photocoupler 18 having a light emitting element and a light receiving element arranged so as to sandwich a part of the pulse plate 17 is arranged. The photocoupler 18 generates a pulse signal every time the light from the light emitting element is received by the light receiving element by the rotation of the pulse plate 17. This pulse signal is input to a focus adjustment circuit 34 (see FIG. 3), which will be described later, and the amount of movement (or position) of the focus lens 3a is detected by counting the number of input pulse signals.

  The aperture drive unit 20 includes an aperture drive circuit 35 (see FIG. 3) described later, and drives the aperture 19 in the opening / closing direction.

  FIG. 3 is a block diagram showing an electrical configuration of the above-described digital single-lens reflex camera. A microcomputer (hereinafter referred to as MPU) 30 is a main controller that controls the camera body 1 and the entire camera system. The memory controller 31 controls the operation of the image sensor 6 and controls related to image data. The EEPROM 32 as a memory stores data for performing various controls.

  A lens control circuit 33 provided in the interchangeable lens 3 controls the focus adjustment circuit 34 and the aperture drive circuit 35 in the interchangeable lens 3 in accordance with a signal from the MPU 30 transmitted via the mount 2.

  Information indicating the target movement amount of the focus lens 3a is input from the lens control circuit 33 to the focus adjustment circuit 34, and a pulse signal (that is, an actual movement amount indicating the actual movement amount of the focus lens 3a) is output from the photocoupler 18. Information) is input. The focus adjustment circuit 34 drives the focus motor 15 based on the information about the target movement amount and the actual movement amount to move the focus lens 3a. The diaphragm drive circuit 35 drives the diaphragm 19 in accordance with the diaphragm drive signal from the lens control circuit 33.

  The focus detection circuit 36 in the camera body 1 controls charge accumulation and charge readout of the area sensor 8d provided in the AF unit 8, and outputs a pair of image signals obtained in each focus detection area to the MPU 30. The MPU 30 calculates a phase difference between the pair of image signals by performing a correlation operation on the input pair of image signals, and further calculates a defocus amount indicating a focus state of the photographing optical system from the phase difference. Based on the defocus amount and optical data such as the focal length of the photographing optical system and the focus sensitivity of the focus lens 3a acquired from the interchangeable lens 3 (lens control circuit 33), the MPU 30 determines the alignment of the focus lens 3a. Calculate the focal position. The focus position (first focus position) obtained by this phase difference detection method is referred to as a phase difference focus position in the following description. The MPU 30 transmits information on the phase difference in-focus position to the lens control circuit 33. The AF unit 8, the focus detection circuit 36, and the MPU 30 constitute a focus control means.

  The lens control circuit 33 calculates a target movement amount of the focus lens 3 a for moving the focus lens 3 a from the current position to the phase difference focusing position, and outputs information on the target movement amount to the focus adjustment circuit 34. Thereby, as described above, the focus adjustment circuit 34 drives the focus motor 15 (not shown) and moves the focus lens 3a to the phase difference in-focus position. In this way, phase difference AF including focus detection and focus adjustment by the phase difference detection method is performed.

  The photometry circuit 37 outputs the luminance signal from the RGB photometry sensor 13 to the MPU 30. The MPU 30 performs A / D conversion of the luminance signal to obtain photometric information of the subject, and uses this photometric information to calculate and set the photographic exposure. A series of operations from obtaining this photometric information to setting the photographic exposure is called an AE operation. Similarly, subject color information is obtained from the RGB signals, and face detection is performed from the imaging signals.

  The motor drive circuit 38 controls a mirror motor (not shown) that drives the main mirror 4 and a charge motor (not shown) that charges the shutter 5. The shutter drive circuit 39 controls power supply to an electromagnet (coil) (not shown) that holds the shutter 5 in a charged state.

  The liquid crystal driving circuit 40 controls the driving of the PN liquid crystal panel 12 and displays a distance measuring point and various information in the finder. The DC / DC converter 41 converts the voltage of the power source (battery) 42 into a voltage necessary for each circuit in the camera body 1 and the interchangeable lens 3. The power source 42 is detachable from the camera body 1.

  The release button 43 is an operation member that is operated to start shooting by the user. When the release button 43 is half-pressed (first stroke operation), the first switch SW1 for starting shooting preparation operations such as AE and AF is turned on. Further, the second switch SW2 for starting the exposure of the image sensor 6 for generating the recording image is turned on by the full pressing operation (second stroke operation) of the release button 43. The ON signals of the first switch SW1 and the second switch SW2 are output to the MPU 30.

  The mode button 44 is operated together with an electronic dial 45 to be described later, so that the shooting mode in the camera body 1 can be changed. In the electronic dial 45, a click signal corresponding to the rotation operation amount is counted by an up / down counter in the MPU 30, and various numerical values and data are selected according to the count value.

  The multi-control button 46 is an operation input unit for selecting or setting the details of a distance measuring point and various shooting modes by the user operating up, down, left, right, and eight buttons provided between them. .

  The SET button 47 is selected or set when the mode button 44, the electronic dial 45, the multi-control button 46, or the like is operated to select or set the details of the ranging point, various shooting modes, various numerical values, and the like. This is an operation input unit for determining. When the power button 48 is operated by the user, the power of the camera body 1 (and the interchangeable lens 3) is turned on / off.

  A CDS (correlated double sampling) / AGC (automatic gain adjustment) circuit 50 performs sample hold and automatic gain adjustment on the imaging signal output from the imaging device 6. The A / D converter 51 converts the analog output from the CDS / AGC circuit 50 into a digital signal. A TG (timing generation) circuit 52 supplies a drive timing signal to the image sensor 6, a sample hold timing signal to the CDS / AGC circuit 50, and a sample clock signal to the A / D converter 51.

  The memory controller 31 detects the in-focus position of the focus lens 3a by the contrast detection method using the imaging signal output from the imaging device 6 and output from the CDS / AGC circuit 50 and the A / D converter 51. The in-focus position (second in-focus position) detected by this contrast detection method is referred to as a contrast in-focus position in the following description. The MPU 30 performs focus calibration for correcting the phase difference focus position based on the difference between the contrast focus position and the phase difference focus position described above. The MPU 30 and the memory controller 31 constitute a calibration means.

  Further, the memory controller 31 uses the output signal from the focus detection pixel of the image sensor 6 to perform the same processing as the phase difference detection method calculated by the MPU 30, and uses the imaging surface phase difference detection method to adjust the focus lens 3a. The focal position is detected. In the following description, the focus position (third focus position) obtained by this imaging surface phase difference detection method is referred to as an imaging surface phase difference focus position.

  The SDRAM 53 as a memory temporarily records data such as images digitally converted by the A / D converter 51 and output signals of focus detection pixels of the image sensor 6. The image processing circuit 54 performs various processes such as Y / C (luminance signal / color difference signal) separation, white balance correction, and γ correction on the imaging signal (digital signal) output from the A / D converter 51. To generate image data for live view or recording. The memory controller 31 can obtain photometric information of the subject (perform so-called imaging surface AE) from the image data generated by the image processing circuit 54.

  The image compression / decompression circuit 55 compresses the image data according to a format such as JPEG or decompresses the compressed image data. The D / A converter 56 converts the image data into an analog signal in order to display the image data recorded on the SDRAM 53 or the recording medium 58 on the liquid crystal monitor 14. An I / F (interface) 57 is an interface with the recording medium 58.

  Next, the operation of the digital single-lens reflex camera of this embodiment will be described using the flowcharts shown in FIGS. The flowchart of FIG. 4 shows an operation performed in the normal calibration mode in which focus calibration is performed. The normal calibration mode is a mode in which focus calibration of a plurality of distance measuring points is simultaneously performed at the position of a certain focus lens 3a. The operations shown in FIGS. 4 and 5 are executed by the MPU 30 and the memory controller 31, which are computers, according to a computer program.

  In step S101, the MPU 30 proceeds to step S102 when the user operates the mode button 44 and the electronic dial 45 to select the normal calibration mode.

  In step S102, the MPU 30 starts live view (LV) display in order to perform focus calibration. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, rotates the main mirror 4 and the sub mirror 7 to the up position, and retracts them from the photographing optical path. Further, the MPU 30 drives a charge motor (not shown) via the shutter drive circuit 39 to open the shutter 5 as shown in FIG. Then, the memory controller 31 causes the image sensor 6 to start photoelectric conversion (charge accumulation and charge read-out), and a live view image, which is a moving image generated by the image processing circuit 54 using the image signal read from the image sensor 6. It is displayed on the liquid crystal monitor 14. The user searches for a subject for focus calibration while viewing the live view image, and places a camera.

  FIG. 6 is a diagram showing a display state of the liquid crystal monitor 14 during live view. A subject road sign 200 is displayed as a live view image on the liquid crystal monitor 14. A TVAF frame 300 is displayed at the center of the shooting screen. In FIG. 6, the TVAF frame 300 is arranged at the center of the photographing screen, but may be arranged anywhere on the photographing screen.

  In step S103, the MPU 30 determines whether or not the release button 43 is pressed halfway by the user and the first switch SW1 is turned on. If it is on, the subject to be subjected to focus calibration is determined, and the process proceeds to step S104. If not, wait until it is turned on.

  In step S104, the MPU 30 drives the focus motor 15 through the lens control circuit 33, and starts driving the focus lens 3a in increments of a predetermined amount.

  In step S105, the contrast focus position of the focus lens 3a is detected by a contrast detection method. Specifically, first, the memory controller 31 reads out an imaging signal in the TVAF frame 300 from the imaging device 6 and extracts a predetermined frequency component to generate a contrast evaluation signal, and temporarily records it in the SDRAM 53. Then, the memory controller 31 determines whether or not an image having the maximum (peak) contrast (hereinafter referred to as a peak image) has been obtained. If a peak image has been detected, the process proceeds to step S106. If it cannot be detected, the peak image is repeatedly detected at the position where the focus lens 3a is driven by a predetermined amount. Since the peak image cannot be detected unless at least three contrast evaluation images are acquired, step S105 is repeated at least three times.

  In step S106, the MPU 30 stops the focus motor 15 through the lens control circuit 33 and ends the driving of the focus lens 3a. At this time, the focus lens 3a is stopped at a position (contrast focus position) where the road sign 200 as a subject for focus calibration is in focus.

  In step S107, 1 is set to the counter N for counting 61 distance measuring points of the area sensor 8d. In step S108, a focus calibration availability determination routine is executed. Detailed operations in this routine will be described later.

  In step S109, it is determined whether or not the execution of the focus calibration availability determination routine has ended at the 61st distance measuring point, that is, all the distance measuring points. If completed, the process proceeds to step S111, and if not completed, the process proceeds to step S110. In step S110, 1 is added to the counter N, and step S108 is repeated.

  In step S111, the memory controller 31 displays on the liquid crystal monitor 14 the result of determining whether or not focus calibration is possible for all distance measuring points of the area sensor 8d. The focus calibration availability determination result can be determined by CAL_OK_FLAG or CAL_NG_FLAG temporarily recorded in the SDRAM 53 in a focus calibration availability determination routine described later.

  FIG. 7 is a diagram showing a state in which the focus calibration availability determination result is displayed on the liquid crystal monitor 14. Reference numeral 800 denotes an AF frame indicating the distance measuring points of the area sensor 8d and is displayed for 61 points. The individual numbers of the AF frame 800 start counting from the upper left as the AF frame 801, from the left end to the right end, from the upper side to the lower side, the center as the AF frame 831, and the lower right as the AF frame 861. Accordingly, the first ranging point of the counter N is the AF frame 801, and the 61st ranging point is the AF frame 861. In addition, a CAL start button 310 and a cancel button 320 are displayed.

  AF points that can be focus-calibrated have AF frames displayed as solid lines (801, 804, 814, 848, 858, 861, etc.). AF points that cannot be focus-calibrated are displayed with dotted lines (803, 831, 859, etc.) so that they can be identified. In FIG. 7, whether or not focus calibration is possible for each focus detection point is indicated by a solid line and a dotted line (differences in line type and line width) of the AF frame, but the display color of the AF frame can be changed, or AF Any display method may be used as long as the frame can be displayed and hidden (or blinked), or the user can visually determine whether or not the frame is visible.

  In step S112, the MPU 30 determines whether or not the CAL start button 310 is turned on by the user. Specifically, when the SET button 47 is operated after the CAL start button 310 is selected by operating the electronic dial 45 or the multi-controller 46, the CAL start button is turned on and the process proceeds to step S113. If it is not turned on (that is, if the cancel button 320 is turned on), the focus calibration mode is terminated.

  In step S113, the live view display ends. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, and rotates the main mirror 4 and the sub mirror 7 to the down position shown in FIG.

  In step S114, the MPU 30 performs focus detection by the phase difference detection method via the focus detection circuit 36 for the distance measurement points that can be focus calibrated, and calculates the phase difference focus position based on the result. , Temporarily recorded in the SDRAM 53.

  In step S115, the MPU 30 calculates the difference between the contrast focus position obtained in step S105 and the phase difference focus position of the focus calibratable distance measuring point obtained in step S114. This difference is a correction amount (hereinafter referred to as a CAL correction amount) with respect to the phase difference in-focus position of the focus calibration capable distance measuring point.

  In step S116, the MPU 30 records the calculated CAL correction amount of the focus calibration available distance measuring point in the EEPROM 32, and ends the operation in the calibration mode.

  Next, the flowchart of FIG. 5 shows operations performed in the focus calibration availability determination routine. This is performed before or during the focus calibration operation.

  In step S151, the memory controller 31 reads out the imaging signal in the AF frame 8NN that is the Nth distance measuring point from the imaging device 6, and generates an evaluation image. In step S152, it is determined whether or not the contrast of the evaluation image is greater than or equal to a predetermined value. If it is greater than or equal to the predetermined value, the process proceeds to step S153, and if it is less than the predetermined value, the process proceeds to step S157.

  In step S153, it is determined whether the luminance of the evaluation image is within a predetermined range value. If it is within the predetermined range value, the process proceeds to step S154. If it is outside the predetermined range value, the process proceeds to step S157.

  In step S154, it is determined whether or not there is a subject competing for perspective in the evaluation image. If there is no subject competing for perspective, the process proceeds to step S155, and if there is a subject competing for perspective, the process proceeds to step S157.

  In step S155, it is determined whether the evaluation image has a repeated pattern. If it is not a repetitive pattern, the process proceeds to step S156, and if it is a repetitive pattern, the process proceeds to step S157.

  In step S156, since all the four determinations of steps S152 to S155 are OK, accurate ranging can be performed with the phase difference AF in step S114, and therefore it is determined that the Nth ranging point can be focus calibrated. Then, the MPU 30 temporarily records the result of the Nth ranging point (AF frame 8NN) in the SDRAM 53 as CAL_OK_FLAG.

  In step S157, since any of the four determinations of steps S152 to S155 is NG, there is a possibility that the phase difference AF may be erroneously measured in step S114 or the distance measurement becomes impossible. It is determined that calibration is impossible. Then, the MPU 30 temporarily records the result of the Nth distance measuring point (AF frame 8NN) as CAL_NG_FLAG in the SDRAM 53, and returns to step S109.

  In FIG. 7, since the subject is the road sign 200, all of the AF frames 801 to 861 have the brightness within the predetermined range value, the subject is not in the distance competing, and the three determinations are OK if the subject is not a repetitive pattern. (Subject determination). However, the contrast differs depending on the position where the AF frame is arranged on the road sign 200. As described above, since the AF frames 801, 804, 814, 848, 858, 861, etc. have a design change in the AF frame (there is an edge line where the color changes), the contrast becomes a predetermined value or more and CAL_OK_FLAG is recorded. . The AF frames 803, 831, 859, etc. have no design change in the AF frame (there is no edge line for switching colors), so the contrast becomes less than a predetermined value and CAL_NG_FLAG is recorded.

  In FIG. 5, whether or not focus detection by the phase difference detection method is possible is performed by using four determination methods of contrast determination, luminance determination, near / far conflict determination, and repeated pattern determination using the image pickup signal from the image pickup device 6. ing. However, if it is a method that can determine a subject for which focus detection accuracy is difficult to obtain by the phase difference detection method, for example, color determination, determination of whether or not the imaging surface phase difference AF of the image sensor 6 can be performed, and the like, Any determination method may be used.

  As described above, according to the present embodiment, it is determined using the imaging signal from the imaging device 6 whether or not focus calibration is possible for the subject selected by the user. As a result, it is possible to prevent useless correction work on a subject for which focus calibration accuracy cannot be achieved. Therefore, the user can easily and efficiently perform the focus calibration without using a dedicated chart.

(Second Embodiment)
The operation of the digital single-lens reflex camera of this embodiment will be described with reference to the flowcharts shown in FIGS. The flowchart of FIG. 8 is performed in a calibration determination mode for determining whether or not focus calibration is possible in a digital single-lens reflex camera system including a digital single-lens reflex camera and an interchangeable lens according to the second embodiment of the present invention. The operation to be performed is shown. The configurations of the camera body and the interchangeable lens of the present embodiment are the same as those of the first embodiment, and in this embodiment, the same reference numerals as those of the first embodiment are assigned to the constituent elements common to the first embodiment. The operations shown in FIGS. 8 and 9 are executed by the MPU 30 and the memory controller 31, which are computers, according to a computer program.

  In step S201, when the MPU 30 detects that the user has operated the mode button 44 and the electronic dial 45 to select the calibration determination mode, the process proceeds to step S202. Since the calibration determination mode of the present embodiment is a mode performed on the viewfinder, the user searches for a subject for focus calibration while looking through the viewfinder.

  In step S202, the MPU 30 determines whether or not the user has pressed the release button 43 halfway to turn on the first switch SW1. If it is on, the subject to be subjected to focus calibration determination is determined, and the process proceeds to step S203. If not, wait until it is turned on.

  In step S203, the MPU 30 drives the focus lens 3a to the phase difference in-focus position obtained by the phase difference detection method. Specifically, first, focus detection by the phase difference detection method is performed via the focus detection circuit 36 at a distance measuring point corresponding to the setting of the camera at that time. For example, if the focus detection point selection mode is one point, focus detection is performed at a focus detection point selected in advance by the user. If automatic selection is performed, focus detection is performed at all 61 points. Based on the result and lens information, the MPU 30 determines the main ranging point. Next, the MPU 30 calculates a phase difference in-focus position based on the focus detection result, and transmits the information to the lens control circuit 33. Next, the lens control circuit 33 calculates the amount of movement of the focus lens 3a, and drives the focus lens 3a to the phase difference in-focus position via the focus adjustment circuit 34.

  In step S203, the MPU 30 performs focus detection by the phase difference detection method via the focus detection circuit 36 for all distance measuring points of the area sensor 8d at the stop position of the focus lens 3a. Based on the result, an AF frame indicating the focused distance measuring point is displayed on the PN liquid crystal panel 12 via the liquid crystal driving circuit 40.

  FIG. 10 is a diagram showing a display state in the viewfinder. A subject image formed on the focusing screen 9 and various information displayed on the PN liquid crystal 12 are displayed through a finder optical system. An image of a building 210 in which a clock electronic bulletin board 211 is installed on the roof is formed as an object on the focus plate 9. The PN liquid crystal 12 displays an AF frame 800 (801 to 803, 807 to 811, 816, 824, 827, 831, 835, 838, 846, 849, 857, etc.) indicating the focusing point in focus. ing.

  In step S205, the MPU 30 counts the focused distance measuring points and sets the counter max value. In FIG. 10, among 61 AF points, the AF frame displayed in focus is 37 points, so max = 37.

  In step S206, 1 is set to a counter M for counting the distance measuring points for determining whether or not focus calibration is possible. In step S207, a focus calibration availability determination routine is executed. Detailed operations in this routine will be described later.

  In step S208, it is determined whether or not the execution of the focus calibration availability determination routine has been completed up to the distance measuring point of the counter max value. If completed, the process proceeds to step S210, and if not completed, the process proceeds to step S209. In step S209, 1 is added to the counter M, and step S207 is repeated.

  In step S210, the memory controller 31 displays the focus calibration availability determination result on the PN liquid crystal 12, and the operation in the calibration determination mode ends. The focus calibration availability determination result can be determined by CAL_OK_FLAG or CAL_NG_FLAG temporarily recorded in the SDRAM 53 in a focus calibration availability determination routine described later.

  FIG. 11 shows a state in which the focus calibration availability determination result is displayed on the PN liquid crystal 12. Of the AF frame 800 displayed in focus in step S204, the AF frames 802 and 806 to 811 for which the focus calibration availability determination result has become impossible are turned off. The AF frames 801, 803, 807, 816, 824, 827, 831, 835, 838, 846, 849, 857, etc. that are continuously lit indicate that focus calibration is possible. In addition, a message 330 is displayed to indicate to the user that the focus calibration availability determination result is displayed.

  In FIG. 11, whether or not focus calibration is possible at each distance measuring point is displayed by turning on (displaying) and turning off (not displaying) the AF frame. However, the display color of the AF frame is changed, or the AF frame is shown as a solid line. Any display method may be used as long as it is a dotted line or the user can visually determine whether or not it is possible. Further, the message 330 to the user is not limited to the wording of the present embodiment, and any wording may be used. Further, a mark indicating whether or not focus calibration is possible may be displayed.

  The flowchart of FIG. 9 shows the operation performed in the focus calibration availability determination routine.

  In step S <b> 251, the memory controller 31 reads out the imaging signal in the AF frame 8 </ b> MM, which is the Mth distance measuring point, from the RGB photometric sensor 13 via the photometric circuit 37 to generate an evaluation image.

  In step S252, it is determined whether the contrast of the evaluation image is greater than or equal to a predetermined value. If it is greater than or equal to the predetermined value, the process proceeds to step S253, and if it is less than the predetermined value, the process proceeds to step S256. In step S253, it is determined whether the luminance of the evaluation image is within a predetermined range value. If it is within the predetermined range value, the process proceeds to step S254, and if it is outside the predetermined range value, the process proceeds to step S256.

  In step S254, it is determined whether or not the subject is moving by checking whether or not the signals such as the contrast and brightness of the evaluation image have varied or fluctuated over a predetermined value. If the subject is not moving, the process proceeds to step S255, and if the subject is moving, the process proceeds to step S256.

  In step S255, since all three determinations in steps S252 to S254 are OK, accurate distance measurement can be performed even by TVAF using the image sensor 6, and therefore it is determined that the Mth distance measurement point can be focus calibrated. Then, the MPU 30 temporarily records the result of the Mth ranging point (AF frame 8MM) in the SDRAM 53 as CAL_OK_FLAG.

  In step S256, since any of the three determinations of steps S252 to S254 is NG, there is a possibility that distance measurement may be erroneously performed by TVAF using the image sensor 6 or the distance measurement may be impossible. Is determined to be impossible. Then, the result of the Mth ranging point (AF frame 8MM) is temporarily recorded in the SDRAM 53 as CAL_NG_FLAG by the MPU 30, and the process returns to step S208.

  In FIG. 10, regarding the AF frame focused by the phase difference AF (displayed by the PN liquid crystal 12), the contrast is equal to or higher than the predetermined value, the luminance is within the predetermined range value, and the two determinations are OK. However, the AF frames 802 and 808 to 811 on the electronic bulletin board 211 of the subject are determined to be incapable of distance measurement by the TVAF because the subject is moving because the time is advanced during the moving body determination and the signal of the evaluation image is changed. And CAL_NG_FLAG is recorded. As a result, as shown in FIG. 11, the AF frames 802 and 808 to 811 are turned off, and only AF frames that can be subjected to focus calibration are displayed.

  In FIG. 9, whether or not focus detection by the contrast detection method is possible is performed by three determination methods of the RGB photometric sensor 13, contrast determination, luminance determination, and moving object determination. However, any method that can determine a subject for which it is difficult to obtain focus detection accuracy by the contrast detection method of the image sensor 6 using the imaging signal from the RGB photometric sensor 13, for example, for determining a more accurate contrast value. Any determination method such as color determination may be used.

  Further, in the present embodiment, only the focus calibration availability determination mode is performed. However, as in the first embodiment, the focus calibration may be performed after the availability determination.

  As described above, according to the present embodiment, it is determined using the imaging signal from the RGB photometric sensor 13 whether or not focus calibration is possible for the subject selected by the user. As a result, it is possible to prevent useless correction work on a subject for which focus calibration accuracy cannot be achieved. Therefore, the user can easily and efficiently perform the focus calibration.

(Third embodiment)
The operation of the digital single-lens reflex camera of this embodiment will be described using the flowcharts shown in FIGS. The flowchart of FIG. 12 shows the basic operation of a camera having an automatic focus calibration function in a digital single-lens reflex camera system including a digital single-lens reflex camera and an interchangeable lens according to a third embodiment of the present invention. The configurations of the camera body and the interchangeable lens of the present embodiment are the same as those of the first embodiment, and in this embodiment, the same reference numerals as those of the first embodiment are assigned to the constituent elements common to the first embodiment. The operations shown in FIGS. 12 and 13 are executed by the MPU 30 and the memory controller 31, which are computers, according to a computer program.

  In step S301, after the user operates the power button 48 to turn on the camera, the user first selects the AF mode. If phase difference AF is selected, the process proceeds to step 302. If TVAF is selected, the process proceeds to step S312.

  In step S302, the MPU 30 determines whether or not the user has pressed the release button 43 halfway to turn on the first switch SW1. If it is on, the subject is confirmed and the process proceeds to step S303. If not, wait until it is turned on.

  In step S303, the MPU 30 performs focus detection by the phase difference detection method at the distance measurement point according to the setting of the camera at that time via the focus detection circuit 36, and calculates the phase difference focus position based on the result. , Temporarily recorded in the SDRAM 53.

  In step S304, it is determined whether or not there is a CAL correction amount at the distance measurement point for which the phase difference in-focus position is calculated. If there is a CAL correction amount, the process proceeds to step 305. If not, the process proceeds to S306.

  In step S 305, the MPU 30 reads the CAL correction amount recorded in the EEPROM 32 and adds it to the phase difference in-focus position temporarily recorded in the SDRAM 53. In step S <b> 306, the MPU 30 transmits the phase difference in-focus position with the CAL correction amount added to the lens control circuit 33. Next, the lens control circuit 33 calculates the amount of movement of the focus lens 3a, and drives the focus lens 3a to the phase difference in-focus position via the focus adjustment circuit 34.

  In step S307, the MPU 30 determines whether or not the release button 43 is fully pressed by the user and the second switch SW2 is turned on. If it is on, the process proceeds to step S308. If not, wait until it is turned on.

  In step S308, the MPU 30 captures a subject. Specifically, first, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, rotates the main mirror 4 and the sub mirror 7 to the up position, and retracts them from the photographing optical path. Next, the MPU 30 drives a charge motor (not shown) via the shutter drive circuit 39 to operate the shutter 5 at a set shutter speed. At the same time, the memory controller 31 causes the image sensor 6 to start photoelectric conversion, and the image processing circuit 54 generates an image using the image signal read from the image sensor 6. When the drive of the shutter 5 is completed, the MPU 30 drives a charge motor (not shown) via the shutter drive circuit 39 to prepare for the next shooting, thereby bringing the shutter 5 into a charged state. Then, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, and rotates the main mirror 4 and the sub mirror 7 from the up position to the down position, thereby completing a series of photographing operations.

  In step S309, the MPU 30 determines whether or not the user has selected the focus calibration mode. If the user selects the focus calibration mode, the process proceeds to step S310. If not, the process proceeds to step S311. In step S310, the selected focus calibration mode is executed. Details will be described later.

  In step S311, the MPU 30 determines whether or not the user has turned off the power by operating the power button 48. If turned off, the camera operation is terminated, and if not turned off, the process returns to step S301 to perform the camera operation. to continue.

  In step S312, in response to the selection of TVAF in step S301, live view display is started. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, rotates the main mirror 4 and the sub mirror 7 to the up position, and retracts them from the photographing optical path. Further, the MPU 30 drives a charge motor (not shown) via the shutter drive circuit 39 to open the shutter 5 as shown in FIG. Then, the memory controller 31 causes the image sensor 6 to start photoelectric conversion, and causes the liquid crystal monitor 14 to display a live view image that is a moving image generated by the image processing circuit 54 using the image signal read from the image sensor 6. Then, the user sets the position of the TVAF frame 300 displayed on the liquid crystal monitor 14 and selects a subject.

  In step S313, the MPU 30 determines whether or not the user has pressed the release button 43 halfway to turn on the first switch SW1. If it is on, the position of the TVAF frame 300 is determined, and the process proceeds to step S303. If not, wait until it is turned on.

  In step S314, the MPU 30 drives the focus motor 15 through the lens control circuit 33, and starts driving the focus lens 3a in increments of a predetermined amount.

  In step S315, the contrast focus position of the focus lens 3a is detected by a contrast detection method. Specifically, first, the memory controller 31 reads out the imaging signal in the TVAF frame 300 from the imaging device 6 to generate a contrast evaluation image, and temporarily records it in the SDRAM 53. Then, the memory controller 31 determines whether or not a peak image has been obtained. If a peak image has been detected, the process proceeds to step S316. If it cannot be detected, the peak image is repeatedly detected at the position where the focus lens 3a is driven by a predetermined amount. Since the peak image cannot be detected unless at least three contrast evaluation images are acquired, step S315 is repeated at least three times.

  In step S316, the MPU 30 stops the focus motor 15 through the lens control circuit 33 and ends the driving of the focus lens 3a.

  In step S317, the MPU 30 determines whether or not the release button 43 is fully pressed by the user and the second switch SW2 is turned on. If it is on, the process proceeds to step S318. If not, wait until it is turned on.

  In step S318, the memory controller 31 causes the image sensor 6 to start photoelectric conversion, and the image processing circuit 54 generates an image using the image signal read from the image sensor 6.

  In step S319, it is determined whether or not the CAL correction amount is recorded in the EEPROM 32 at the distance measurement point that overlaps the position of the TVAF frame 300 in which the contrast is in focus or at a distance measurement point that is arranged in the vicinity thereof. If the CAL correction amount is not recorded, the process proceeds to step S320 to execute the automatic focus calibration function for the distance measuring point, and if it is recorded, the process proceeds to step S325. Here, the CAL correction amount is confirmed using a specific distance measuring point, but may be all distance measuring points.

  In step S320, the live view display ends. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, and rotates the main mirror 4 and the sub mirror 7 to the down position shown in FIG.

  In step S321, the MPU 30 performs focus detection by the phase difference detection method via the focus detection circuit 36 for the distance measuring point at which automatic focus calibration is performed, calculates the phase difference in-focus position based on the result, and sends the result to the SDRAM 53. Record temporarily.

  In step S322, the MPU 30 calculates the difference between the contrast focus position obtained in step S315 and the phase difference focus position of the distance measuring point obtained in step S321. This difference becomes the CAL correction amount with respect to the phase difference in-focus position of the focus calibration capable distance measuring point.

  In step S323, the MPU 30 records the calculated CAL correction amount of the distance measuring point in the EEPROM 32. In step S324, the AF frame 800 of the distance measuring point where the CAL correction amount is recorded is displayed, and the result of the automatic focus calibration is displayed on the liquid crystal monitor 14. Here, any display method may be used as long as the user can visually recognize the result of the automatic focus calibration.

  In step S325, it is determined whether or not the user has ended the live view display. If the user has performed an operation to end, the process proceeds to step S309. If the operation has not been performed, the process proceeds to step S313, and the live view display is continued. .

  The flowchart of FIG. 13 shows the operation performed in the detailed calibration mode for performing the focus calibration. The detailed calibration mode is a mode for performing focus calibration of all the distance measuring points by repeating TVAF and phase difference AF for each distance measuring point.

  In step S401, the MPU 30 proceeds to step S402 when the user operates the mode button 44 and the electronic dial 45 to select the detailed calibration mode.

  In step S402, the focus calibration operation timer T starts to be counted. Here, the operation timer T may be automatically set by the camera, or may be configured so that the user can set it in advance. In step S403, 1 is set to a counter N for counting 61 distance measuring points of the area sensor 8d.

  In step S404, it is determined whether or not the CAL correction amount at the Nth distance measuring point is recorded in the EEPROM 32. If it is recorded, the process proceeds to step S405, and if it is not recorded, the process proceeds to step S406. Here, it is determined that focus calibration is not performed again for distance measuring points for which the automatic focus calibration function in steps S319 to S324 is executed and the CAL correction amount is recorded. In step S405, the MPU 30 adds 1 to the counter N and repeats the determination in step S404.

  In step S406, the MPU 30 starts live view display in order to perform focus calibration. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, rotates the main mirror 4 and the sub mirror 7 to the up position, and retracts them from the photographing optical path. Further, the MPU 30 drives a charge motor (not shown) via the shutter drive circuit 39 to open the shutter 5 as shown in FIG. Then, the memory controller 31 causes the image sensor 6 to start photoelectric conversion, and causes the liquid crystal monitor 14 to display a live view image that is a moving image generated by the image processing circuit 54 using the image signal read from the image sensor 6. The user searches for a subject for focus calibration while viewing the live view image, and places a camera.

  In step S407, the MPU 30 drives the focus motor 15 through the lens control circuit 33, and starts driving the focus lens 3a in increments of a predetermined amount. In step S408, the contrast focus position of the focus lens 3a is detected by a contrast detection method. Specifically, first, the memory controller 31 reads out the imaging signal in the TVAF frame 300 from the imaging device 6 to generate a contrast evaluation image, and temporarily records it in the SDRAM 53. Then, the memory controller 31 determines whether or not a peak image has been obtained. If a peak image has been detected, the process proceeds to step S409. If it cannot be detected, the peak image is repeatedly detected at the position where the focus lens 3a is driven by a predetermined amount. Since the peak image cannot be detected unless at least three contrast evaluation images are acquired, step S408 is repeated at least three times.

  In step S409, the MPU 30 stops the focus motor 15 through the lens control circuit 33 and finishes driving the focus lens 3a. In step S410, a focus calibration availability determination routine is executed. Here, the focus calibration availability determination routine is the same routine as in FIG.

  In step S411, the MPU 30 determines the result of the focus calibration availability determination routine for the Nth distance measuring point. If CAL_OK_FLAG is reached, the process proceeds to step S412.

  In step S412, live view display ends. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, and rotates the main mirror 4 and the sub mirror 7 to the down position shown in FIG.

  In step S413, the MPU 30 performs focus detection by the phase difference detection method for the Nth distance measuring point via the focus detection circuit 36, calculates the phase difference in-focus position based on the result, and temporarily records it in the SDRAM 53. To do.

  In step S414, the MPU 30 calculates the difference between the contrast focus position obtained in step S408 and the phase difference focus position obtained in step S413. This difference becomes the CAL correction amount for the phase difference in-focus position of the Nth distance measuring point.

  In step S415, the MPU 30 records the calculated CAL correction amount of the Nth distance measuring point in the EEPROM 32. In step S416, the MPU 30 determines whether or not the camera 1 is set on a tripod using a sensor (not shown). If it is set, the process proceeds to step S418. If not set, the process proceeds to step S417.

  In step S417, it is determined whether or not the set time of the operation timer T has elapsed. If it has elapsed, the process proceeds to step S419, and if not, the process proceeds to step S418.

  In step S418, it is determined whether or not the focus calibration has completed the 61st distance measuring point, that is, all the distance measuring points. If completed, the process proceeds to step S419, and if not completed, the process proceeds to step S405.

  In step S419, the focus calibration result is displayed on the liquid crystal monitor 14 in response to whether the focus calibration of all focus detection points has been completed or the focus calibration operation timer T has expired. The display method may be any display method as long as the user can visually recognize the result. When the display is completed, the process returns to step S311.

  As described above, according to the present embodiment, focus calibration can be prevented from being performed for distance measurement points for which the CAL correction amount has been set by automatic focus calibration. If there are many distance measuring points and it takes time for focus calibration, focus calibration can be performed only within a preset time. Further, when a tripod is used, focus calibration of all distance measuring points can be performed regardless of a preset time. Therefore, the user can easily and efficiently perform the focus calibration.

  In the present embodiment, the operation timer T is ignored when using a tripod, but the time may be extended. Further, the time may be set by the user. The focus calibration operation is limited by a preset operation timer T, but may be limited by a camera shake amount by an acceleration sensor (not shown) in the camera or in the lens. For example, the continuation of focus calibration may be determined by determining the blur amount threshold, or the time limit operation timer T may be extended when the blur amount is small. Furthermore, the focus calibration may be stopped when a large amount of blur is measured.

(Fourth embodiment)
The operation of the digital single-lens reflex camera of this embodiment will be described with reference to the flowcharts shown in FIGS. The flowchart in FIG. 14 shows an operation performed in the normal calibration mode in which focus calibration is performed. The normal calibration mode is a mode in which focus calibration of a plurality of distance measuring points is simultaneously performed at the position of a certain focus lens 3a. The configurations of the camera body and the interchangeable lens of the present embodiment are the same as those of the first embodiment, and in this embodiment, the same reference numerals as those of the first embodiment are assigned to the constituent elements common to the first embodiment. 14 and 5 are executed by the MPU 30 and the memory controller 31, which are computers, according to a computer program.

  In step S1101, the MPU 30 proceeds to step S1102 when the user operates the mode button 44 and the electronic dial 45 to select the normal calibration mode.

  In step S1102, the MPU 30 displays on the liquid crystal monitor 14 whether or not to shift to a mode in which it is possible to determine whether or not an appropriate focus correction value has been obtained by focus calibration by changing the AF frame display of the phase difference AF distance measuring point. . If it is performed in the normal focus calibration mode, the process proceeds to step S1110.

  Here, the diagram showing the state in which the focus calibration availability determination result is displayed on the liquid crystal monitor 14 is the same as FIG. 7 shown in the first embodiment.

  FIG. 15 shows a display 180 on the liquid crystal monitor 14 in the case of shifting to a mode in which AF frame (803, 831, 859, etc.) display is individually set after execution of calibration based on the result of focus calibration availability determination. .

  In step S1103, the MPU 30 proceeds to step S1104 when selecting the phase difference AF distance measurement point identification display in the mode of step S1102 from data preset and stored in the imaging apparatus, and displays a new distance measurement point display. When customizing the identification method, the process proceeds to step S1105.

  FIG. 16 shows that “Yes” 181 is selected when the AF frame (800) display at the time of determining whether or not focus calibration is possible is selected from data already stored in the MPU 30 of the digital single-lens reflex camera. To newly set the display of the AF frame (800) after determining whether or not focus calibration is possible, “No” 185 is selected.

  In step S1104, the AF frame display (803, 831, 859, etc.) at the time of focus calibration set or selected by the user is temporarily stored in the MPU 30 of the digital single-lens camera. FIG. 17 shows the display on the liquid crystal monitor 14 before the start of LV after the AF frame (800) display setting at the time of focus calibration is completed.

  In step S1105, it is set whether to specify the number of times of focus calibration.

  FIG. 18 shows a display on the liquid crystal monitor 14 when setting the number of times of execution of focus calibration. The number of times is selected from the number selection display 183 by a touch operation of the electronic dial 45, the multi-controller 46, or the liquid crystal monitor 14, and the number of times is set.

  In step S1106, the display method of the phase difference ranging point that has been executed up to the storage of the focus correction value in the setting for performing the focus calibration a plurality of times is set.

  In FIG. 19, when the focus calibration determination result is acceptable, or the AF frame (800) display setting at which an appropriate focus correction value is obtained is selected by a touch operation of the electronic dial 45, the multi-controller 46, or the liquid crystal monitor 14. The screen to be displayed is shown.

  In step S1107, the display method of the phase difference ranging point where an appropriate focus correction value was not obtained in the setting for performing the focus calibration a plurality of times is set.

  FIG. 20 shows a screen for selecting the AF frame (800) display setting when the focus calibration determination result is not possible, by touching the electronic dial 45, the multi-controller 46, or the liquid crystal monitor 14.

  In step S1108, it is set whether to limit the focus detection points for focus calibration.

  FIG. 21 shows a screen for selecting the AF frame (800) display setting when the range-finding points for focus calibration are limited and the determination result is acceptable by touch operation of the electronic dial 45, the multi-controller 46, or the liquid crystal monitor 14. Show. As an example, the selected distance measuring point 184 displays differently from the unselected distance measuring points. If the focus detection points for focus calibration are not limited, “ALL” 186 is selected. When the selection of the distance measuring point is completed, “OK” 181 is selected.

  In step S1109, in order to confirm the settings from step S1105 to step S1108, a display for confirming the AF frame display setting is performed on the PN liquid crystal panel 12.

  FIG. 22 shows a screen displayed on the liquid crystal monitor 14 in order to confirm the setting contents of the AF frame (800) display when the individual distance measuring point identification display is set during the focus calibration.

  In step S1110, the MPU 30 starts live view (LV) display in order to perform focus calibration. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, rotates the main mirror 4 and the sub mirror 7 to the up position, and retracts them from the photographing optical path. Further, the MPU 30 drives a charge motor (not shown) via the shutter drive circuit 39 to open the shutter 5 as shown in FIG. Then, the memory controller 31 causes the image sensor 6 to start photoelectric conversion (charge accumulation and charge read-out), and a live view image, which is a moving image generated by the image processing circuit 54 using the image signal read from the image sensor 6. It is displayed on the liquid crystal monitor 14. The user searches for a subject for focus calibration while viewing the live view image, and places a camera.

  FIG. 6 is a diagram showing the display state of the liquid crystal monitor 14 during live view, as described in the first embodiment. A subject road sign 200 is displayed as a live view image on the liquid crystal monitor 14. A TVAF frame 300 is displayed at the center of the shooting screen. In FIG. 6, the TVAF frame 300 is arranged at the center of the photographing screen, but may be arranged anywhere on the photographing screen.

  In step S1111, the MPU 30 determines whether or not the release button 43 is half-pressed by the user to turn on the first switch SW1. If it is turned on, the subject to be subjected to focus calibration is determined, and the process proceeds to step S1112. If not, wait until it is turned on.

  In step S1112, the MPU 30 drives the focus motor 15 through the lens control circuit 33, and starts driving the focus lens 3a in increments of a predetermined amount. In step S1113, the contrast focus position of the focus lens 3a is detected by a contrast detection method. Specifically, first, the memory controller 31 reads out the imaging signal in the TVAF frame 300 from the imaging device 6 to generate a contrast evaluation image, and temporarily records it in the SDRAM 53. Then, the memory controller 31 determines whether or not an image having the maximum (peak) contrast (hereinafter referred to as a peak image) has been obtained. If a peak image has been detected, the process proceeds to step S1114. If it cannot be detected, the peak image is repeatedly detected at the position where the focus lens 3a is driven by a predetermined amount. Since the peak image cannot be detected unless at least three contrast evaluation images are acquired, step S1113 is repeated at least three times.

  In step S1114, the MPU 30 stops the focus motor 15 through the lens control circuit 33 and ends the driving of the focus lens 3a. At this time, the focus lens 3a is stopped at a position (contrast focus position) where the road sign 200 as a subject for focus calibration is in focus.

  In step S1115, 1 is set to the counter N for counting 61 distance measuring points of the area sensor 8d. In step S1116, a focus calibration availability determination routine is executed. Detailed operations in this routine will be described later.

  In step S117, it is determined whether or not the execution of the focus calibration availability determination routine has ended at the 61st distance measuring point, that is, all the distance measuring points. If completed, the process proceeds to step S1119, and if not completed, the process proceeds to step S1118. In step S1118, 1 is added to the counter N, and step S1116 is repeated.

  In step S1119, the memory controller 31 displays the focus calibration availability determination result of the AF distance measurement frame corresponding to the area sensor 8d on the liquid crystal monitor 14 so as to correspond to the phase difference AF frame set in step S1106 and step S1107. The focus calibration availability determination result can be determined by CAL_OK_FLAG or CAL_NG_FLAG temporarily recorded in the SDRAM 53 in a focus calibration availability determination routine described later.

  As described in the first embodiment, FIG. 7 shows a state where the focus calibration availability determination result is displayed on the liquid crystal monitor 14. Reference numeral 800 denotes an AF frame indicating the distance measuring points of the area sensor 8d and is displayed for 61 points. The individual numbers of the AF frame 800 start counting from the upper left as the AF frame 801, from the left end to the right end, from the upper side to the lower side, the center as the AF frame 831, and the lower right as the AF frame 861. Accordingly, the first ranging point of the counter N is the AF frame 801, and the 61st ranging point is the AF frame 861. In addition, a CAL start button 310 and a cancel button 320 are displayed.

AF points that can be focus-calibrated have AF frames displayed as solid lines (801, 804, 814, 848, 858, 861, etc.). AF points that cannot be subjected to focus calibration are indicated by dotted lines in the AF frame (803, 831, 859, etc.). In the example of FIG. 7, whether or not focus calibration of each distance measuring point is possible is displayed by a solid line and a dotted line of the AF frame. In step S1120, the MPU 30 determines whether or not the CAL start button 310 is turned on by the user. . Specifically, when the SET button 47 is operated after the CAL start button 310 is selected by operating the electronic dial 45 or the multi-controller 46, the CAL start button is turned on and the process proceeds to step S1121. If it is not turned on (that is, if the cancel button 320 is turned on), the focus calibration mode is terminated.

  In step S1121, live view display ends. Specifically, the MPU 30 controls a mirror motor (not shown) via the motor drive circuit 38, and rotates the main mirror 4 and the sub mirror 7 to the down position shown in FIG.

  In step S1122, the MPU 30 performs focus detection by the phase difference detection method via the focus detection circuit 36 for the distance measurement points that can be focus calibrated, and calculates the phase difference focus position based on the result. , Temporarily recorded in the SDRAM 53.

  In step S1123, the MPU 30 calculates the difference between the contrast in-focus position obtained in step S1105 and the phase difference in-focus position of the focus calibratable distance measurement point obtained in step S1122. This difference is a correction amount (hereinafter referred to as a CAL correction amount) with respect to the phase difference in-focus position of the focus calibration capable distance measuring point. In step S <b> 1124, the MPU 30 stores the calculated CAL correction amount of the focus calibration available distance measuring point in the EEPROM 32.

  In step S1125, if the number set in step S1105 is not reached, the process returns to step S1110, and LV is started continuously. When the set number of times in step S1105 is satisfied, or when the forced termination is performed, the calibration mode operation is terminated.

  The flowchart of FIG. 5 shows the operation performed in the focus calibration availability determination routine at all distance measuring points. Since this operation has already been described in the first embodiment, a description thereof will be omitted.

  FIG. 23 shows that, in a digital single-lens reflex camera in which all 61 distance measuring points are arranged, focus calibration is possible when the first focus calibration determination is performed based on the same situation and the contrast determination criteria described in FIG. FIG. 10 is a diagram illustrating a distance measuring point that is determined as a thick solid line AF frame 872 and a distance measuring point that is determined as a negative determination as a solid line AF frame 870. In this state, when the CAL start button 310 is selected in the case of OK, the first focus calibration is started, and in the case of NG, the cancel button 320 is selected. The number of focus calibrations is confirmed on the display 330.

  In FIG. 24, the focus points that have completed the first focus calibration and have been stored up to the focus correction value are represented by dotted AF frames 871, and the focus points for which no focus correction value has been acquired are represented by solid AF frames 870. Next, in order to perform the second focus calibration, the digital single lens reflex camera is moved so that the solid AF frame 870 is placed on the edge line of the road sign 200, and the focus calibration is performed at the position of the road sign 200 and the AF frame shown in FIG. The CAL start button 310 is selected to start the second action.

  FIG. 25 is a diagram illustrating a distance measuring point that has been subjected to the second focus calibration and has been stored until the focus correction value is stored, as a dotted AF frame 871, and as a solid AF frame 870 for which no focus correction value has been acquired. Next, in order to perform the focus calibration of the solid line AF frame 870 for the third time, the position of the road sign 200 and the AF frame is changed in the same manner as described above to obtain the positional relationship as shown in FIG.

  FIG. 26 is a diagram in which a focus point that has been subjected to the third focus calibration and has been stored until the focus correction value is stored is represented as a dotted AF frame 871, and a focus point for which no focus correction value has been acquired is represented as a solid AF frame 870. It is. Next, in order to perform the focus calibration of the solid line AF frame 870 for the fourth time, the position of the road sign 200 and the AF frame is changed in the same manner as described above, and the positional relationship shown in FIG. 27 is obtained.

  In FIG. 27, when all focus detection points have been stored up to the focus correction value storage in the focus calibration and become the dotted AF frame 871, the CAL end button 340 is selected to end the focus calibration.

  As described above, according to the present embodiment, it is determined using the imaging signal from the imaging device 6 whether or not focus calibration is possible for the subject selected by the user. As a result, it is possible to easily identify acquisition and non-acquisition of an appropriate focus correction value among a plurality of phase difference AF distance measurement points due to a difference in accuracy of focus calibration, and it is possible to prevent useless correction work. Therefore, the user can easily and efficiently perform the focus calibration without using a dedicated chart.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

1: camera body, 3: interchangeable lens, 5: shutter, 6: image sensor, 8: AF unit, 14: liquid crystal monitor

An imaging apparatus according to the present invention includes an imaging unit that photoelectrically converts an object image formed by an imaging optical system to generate an imaging signal, and a phase difference using a selected focus detection area among a plurality of focus detection areas. First focus detection means for detecting a first in- focus position of the photographing optical system by detection-type focus detection; and second detection of the photographing optical system by focus detection using a different method from the first focus detection means . Calculated from the difference between the second focus position and the first focus position in the correction mode, the second focus detection means for detecting the focus position, the control means for controlling the display of the focus detection area, and the correction mode. Correction means for acquiring a correction amount for correcting the first in-focus position using the correction amount to be obtained , and whether or not the correction amount in each of the plurality of focus detection areas can be acquired in the correction mode. and determining-size constant means, Wherein the control means among the plurality of focus detection areas, by the determination means, the first focus detection area in which the is determined that the correction quantity can be acquired, it is determined not to get the correction amount Further, the display is controlled so as to be distinguishable from the second focus detection area .

Claims (16)

Imaging means for photoelectrically converting a subject image formed by the imaging optical system to generate an image signal;
Phase difference detection means for detecting a first focus position of a focus lens included in the photographing optical system by a phase difference detection method based on a pair of image signals of the subject image;
Contrast detection means for detecting a second in-focus position of the focus lens by a contrast detection method using the image signal;
Calibration means for correcting the first focus position using a correction amount calculated from a difference between the second focus position and the first focus position;
Subject determination means for determining whether or not the subject image is suitable for detection of an in-focus position by the phase difference detection means or the contrast detection means before or during the calibration operation by the calibration means;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, wherein the subject determination unit determines based on an output of the imaging unit.   The imaging apparatus according to claim 1, wherein the subject determination unit performs determination based on an output of a photometry unit for measuring the subject image.   The imaging apparatus according to claim 1, wherein the subject determination unit determines whether or not the subject is a subject image for which the phase difference detection unit cannot detect the first in-focus position.   The imaging apparatus according to claim 1, wherein the subject determination unit determines whether the subject is a subject for which the contrast detection unit cannot detect the second in-focus position.   The imaging apparatus according to claim 1, further comprising a limiting unit that limits a calibration operation by the calibration unit.   The imaging apparatus according to claim 1, further comprising display means for displaying a determination result by the subject determination means.   The imaging apparatus according to claim 7, wherein the display unit is provided outside the imaging apparatus.   The image pickup apparatus according to claim 7, wherein the display unit is provided in an optical system of a finder of the image pickup apparatus.   The image pickup apparatus according to claim 6, wherein the display unit displays whether or not an appropriate focus correction value has been obtained after the calibration is performed so as to be identifiable for each AF frame.   The image pickup apparatus according to claim 10, wherein the display unit displays whether an appropriate focus correction value is obtained by turning on, blinking, or turning off the AF frame.   The image pickup apparatus according to claim 10, wherein the display unit displays whether an appropriate focus correction value is obtained by changing a line type or a line width of the AF frame.   The image pickup apparatus according to claim 10, wherein the display unit displays whether an appropriate focus correction value is obtained by changing a color of the AF frame. An imaging unit that photoelectrically converts a subject image formed by the photographing optical system to generate an image signal, and a focus lens included in the photographing optical system by a phase difference detection method based on a pair of image signals of the subject image A control method for an imaging apparatus, comprising: a phase difference detection unit that detects a first focus position; and a contrast detection unit that detects a second focus position of the focus lens by a contrast detection method using the image signal. Because
A calibration step of correcting the first focus position using a correction amount calculated from a difference between the second focus position and the first focus position;
A subject determination step for determining whether or not the subject image is suitable for detection of an in-focus position by the phase difference detection unit or the contrast detection unit before or during the calibration operation by the calibration step;
A method for controlling an imaging apparatus, comprising:   The program for making a computer perform each process of the control method of Claim 14.   The computer-readable storage medium which memorize | stored the program for making a computer perform each process of the control method of Claim 14.

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