JP2018081289A - IMAGING DEVICE, IMAGING DEVICE CONTROL METHOD, AND FOCUS CONTROL PROGRAM - Google Patents

Abstract

An object of the present invention is to provide a favorable focus state in evaluation of a captured image even when it is easily affected by image blur. An imaging apparatus includes a focus detection unit that detects a focus state of an imaging optical system and generates focus detection information, and a correction value acquisition unit that acquires a correction value for correcting the focus detection information. And control means 125 for performing focus control using the focus detection information corrected by the correction value. The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated. The first evaluation band when the first exposure time, which is the exposure time during imaging, is longer than the first predetermined time is the first evaluation band when the first exposure time is shorter than the first predetermined time. Low compared. [Selection] Figure 1

Description

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

  As an automatic focus adjustment (AF) system in which the imaging apparatus uses an imaging element as a focus detection sensor, there are contrast AF and imaging plane phase difference AF. In both the contrast AF and the imaging surface phase difference AF, the focus state is detected from the focus detection image generated through the image sensor, so that the detected focus state is affected by the spatial frequency distribution of the focus detection image. . For example, when there is image blur due to subject movement, camera shake, and zooming operation of the imaging optical system, the spatial frequency is distributed in a low range as a whole.

  Patent Document 1 discloses an imaging apparatus that corrects a difference between an optimal focus state as a captured image and a focus state detected in AF. Patent Document 2 discloses an imaging apparatus that detects a tendency of a change in image blur and performs AF in a state where the image blur is stable in order to perform AF without being affected by the image blur.

JP2015-138200A JP 2014-38196 A

  The spatial frequency band (evaluation band) for evaluating the focus state of the captured image and the focus state of the focus detection image are one of the factors that cause a difference between the optimum focus state for the captured image and the focus state detected by AF. The difference from the evaluation number band to be evaluated can be mentioned. In particular, as described above, if there is image movement due to subject movement, camera shake, zooming operation of the imaging optical system, or the like, the spatial frequency of the focus detection image is lowered, and the AF accuracy is lowered accordingly. As a result, the difference between the evaluation band of the captured image and the evaluation band at the time of focus detection increases.

  The present invention provides an imaging apparatus capable of obtaining a favorable focus state in evaluation of a captured image even when it is easily affected by image blur.

  An imaging apparatus according to an aspect of the present invention includes a focus detection unit that detects a focus state of an imaging optical system and generates focus detection information, and a correction value acquisition unit that acquires a correction value for correcting the focus detection information. And control means for performing focus control using the focus detection information corrected by the correction value. The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated. The first evaluation band when the first exposure time that is the exposure time at the time of imaging is longer than the first predetermined time is the first evaluation band when the first exposure time is shorter than the first predetermined time. It is characterized by being lower than the bandwidth.

  An imaging apparatus according to another aspect of the present invention includes a focus detection unit that detects a focus state of an imaging optical system and generates focus detection information, and a correction that acquires a correction value for correcting the focus detection information. A value acquisition unit, and a control unit that performs focus control using the focus detection information corrected by the correction value. The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated. The first evaluation band when the first image blur amount, which is the image blur amount at the time of imaging, is larger than the first predetermined amount is the first evaluation band when the first image blur amount is smaller than the first predetermined amount. It is characterized by being lower than the evaluation band of 1.

  A control method according to another aspect of the present invention is applied to an imaging apparatus having a focus detection unit that detects a focus state of an imaging optical system and generates focus detection information. The control method includes a step of obtaining a correction value for correcting the focus detection information, and a step of performing focus control using the focus detection information corrected by the correction value. The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated. The first evaluation band when the first exposure time that is the exposure time at the time of imaging is longer than the first predetermined time is the first evaluation band when the first exposure time is shorter than the first predetermined time. It is characterized by being lower than the bandwidth.

  A control method according to another aspect of the present invention is applied to an imaging apparatus having a focus detection unit that detects a focus state of an imaging optical system and generates focus detection information. The control method includes a step of obtaining a correction value for correcting the focus detection information, and a step of performing focus control using the focus detection information corrected by the correction value. The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated. The first evaluation band when the first image blur amount, which is the image blur amount at the time of imaging, is larger than the first predetermined amount is the first evaluation band when the first image blur amount is smaller than the first predetermined amount. It is characterized by being lower than the evaluation band of 1.

  Note that a focus control program as a computer program that causes the computer of the imaging apparatus to execute processing according to the control method also constitutes another aspect of the present invention.

  According to the present invention, it is possible to obtain a good focus state in evaluation of a captured image even when it is easily affected by image blur.

5 is a flowchart showing AF processing and focus evaluation information acquisition processing in Embodiment 1 of the present invention. 1 is a block diagram illustrating a configuration of an imaging apparatus according to a first embodiment. FIG. 3 is a diagram illustrating a configuration of an image sensor in Embodiment 1. FIG. 3 is a diagram illustrating a relationship between a photoelectric conversion region and an exit pupil in the first embodiment. The block diagram which shows the structure of the TVAF part shown in FIG. FIG. 3 is a diagram illustrating a focus detection area in Embodiment 1. FIG. 6 is a diagram illustrating BP correction information according to the first embodiment. FIG. 4 is a diagram illustrating focus evaluation information and MTF peak positions in the first embodiment. FIG. 3 is a diagram illustrating an evaluation band in the first embodiment. The flowchart which shows the focus evaluation information acquisition process in Example 2 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 shows a configuration of a lens-interchangeable single-lens reflex camera (hereinafter referred to as a camera body) 120 as an image pickup apparatus that is Embodiment 1 of the present invention. The lens unit 100 is detachably mounted on the camera body 120 via a mount M indicated by a dotted line in the drawing.

  The lens unit 100 includes a first optical group 101, an aperture 102, a second lens group 103, a focus lens group (hereinafter simply referred to as “focus lens”) 104, a lens drive / control system, Have The imaging optical system forms an optical image of the subject.

  The first lens group 101 is disposed on the most object side of the lens unit 100 and is held so as to be movable in the optical axis direction in which the optical axis OA extends. The diaphragm 102 functions as a mechanical shutter that controls the exposure time when capturing a still image, in addition to the function of adjusting the amount of light. The aperture 102 and the second lens group 103 are integrally movable in the optical axis direction, and perform zooming by moving in conjunction with the first lens group 101. The focus lens 104 is movable in the optical axis direction, and the subject distance (focusing distance) at which the imaging optical system is focused changes according to the position. By controlling the position of the focus lens 104 in the optical axis direction, focus control (AF) for adjusting the in-focus distance of the imaging optical system can be performed.

  The lens driving / control system includes a zoom actuator 111, an aperture actuator 112, a focus actuator 113, a zoom drive circuit 114, an aperture stop drive circuit 115, a focus drive circuit 116, a lens MPU 117, and a lens memory 118. The zoom drive circuit 114 uses the zoom actuator 111 to drive the first lens group 101 and the third lens group 103 in the optical axis direction to perform zooming. The diaphragm drive circuit 115 drives the diaphragm 102 using the diaphragm actuator 112 and controls the aperture diameter and opening / closing operation of the diaphragm 102. The focus drive circuit 116 uses the focus actuator 113 to drive the focus lens 104 in the optical axis direction to perform focus adjustment. The focus driving circuit 116 detects the current position of the focus lens 104 by detecting the driving amount of the focus actuator 113.

  A lens MPU (microprocessor) 117 performs calculation and control related to the lens unit 100 and controls the zoom drive circuit 114, the aperture drive circuit 115, and the focus drive circuit 116. The lens MPU 117 is electrically connected to the camera MPU 125 in the camera body 120 through the mount M, and communicates various commands and data with the camera MPU 125. For example, the lens MPU 117 transmits lens position information to the camera MPU 125 in response to a request from the camera MPU 125. The lens position information includes the position of the focus lens 104 in the optical axis direction, the position and diameter of the exit pupil of the imaging optical system in a stationary state in the optical axis direction, and the optical axis direction of the lens holding frame that restricts the luminous flux of the exit pupil. Includes information such as position and diameter. The lens MPU 117 controls the zoom drive circuit 114, the aperture drive circuit 115, and the focus drive circuit 116 in accordance with a control command from the camera MPU 125.

  The lens memory 118 stores optical information necessary for AF in advance. The camera MPU 125 controls the operation of the lens unit 100 by executing a program stored in a built-in nonvolatile memory, the lens memory 118, or the like. The camera MPU 125 functions as a correction value acquisition unit and a control unit.

  The camera body 120 includes an imaging unit including an optical low-pass filter 121 and an imaging element 122, and a camera drive / control system. The imaging optical system in the lens unit 100 and the imaging unit in the camera body 120 may be combined and handled as an imaging optical system. The optical low-pass filter 121 is a filter for reducing false colors and moire generated in a captured image. The image sensor 122 includes a CMOS image sensor and its peripheral circuits, and has m pixels that are a plurality of pixels in the horizontal direction and n pixels that are a plurality of pixels in the vertical direction. The image sensor 122 photoelectrically converts the subject image and outputs an electrical signal (imaging signal) used to generate a captured image or a contrast AF (TVAF) image. In addition, the image sensor 122 has a pupil division function, and can output an electrical signal (phase difference image signal) used for generating a phase difference AF image by using the pupil division function. The pupil division function of the image sensor 122 will be described later.

  The camera drive / control system includes a sensor drive circuit 123, an image processing circuit 124, a camera MPU 125, a display 126, an operation switch group 127, a memory 128, a phase difference AF unit 129, and a TVAF unit 130. The sensor drive circuit 123 controls the drive of the image sensor 122, A / D converts the analog electric signal output from the image sensor 122, generates a digital signal, and the digital signal (image data) is converted into the camera MPU 125 and The image is output to the image processing circuit 124. The image processing unit 124 performs image processing such as γ conversion, white balance, color interpolation, and compression coding on the input image data to generate a captured image, or a TVAF) image or a phase difference AF. Or generate an image.

  The camera MPU (microprocessor) 125 performs various calculations related to the camera body 120, and also includes a sensor driving circuit 123, an image processing circuit 124, a display 126, an operation switch group 127, a memory 128, a phase difference AF unit 129, and a TVAF unit. 130 is controlled. As described above, the camera MPU 125 is electrically connected to the lens MPU 117 via the mount M and communicates with the lens MPU 117. The camera MPU 125 transmits to the lens MPU 117 an acquisition request for lens position information, an aperture, focus and zoom drive request, an acquisition request for optical information, and the like. The camera MPU 125 includes a ROM 125a that stores programs, a RAM 125b that stores variables, and an EEPROM 125c that stores various parameters.

  The display 126 is configured by an LCD or the like, and displays information related to the imaging mode, a live view image before focusing, a focused state display image, a confirmation image after imaging, and the like. The operation switch group 127 includes a power switch, a release (imaging trigger) switch, a zoom operation switch, an imaging mode selection switch, and the like. The memory 128 is a flash memory that can be attached to and detached from the camera body 120 and records captured images.

  A phase difference AF unit 129 serving as a focus detection unit performs phase difference AF using the phase difference AF image generated by the image processing circuit 124. Specifically, the phase difference AF unit 129 obtains a pair of phase difference images corresponding to the same area of the subject from the phase difference AF image, and based on the shift amount (phase difference) between the pair of phase difference images. Thus, a defocus amount is calculated as focus detection information indicating the focus state of the imaging optical system. The operation of the phase difference AF unit 129 will be described in detail later. The TVAF unit 130 as another focus detection unit generates a contrast evaluation value as focus detection information indicating the contrast state of the TVAF image generated by the image processing circuit 124 (that is, the focus state of the imaging optical system). . Then, a moving direction and a moving amount of the focus lens 104 for making the contrast evaluation value close to the maximum are calculated. In this embodiment, the imaging surface phase difference AF and TVAF can be selectively used or combined in accordance with the situation.

  Processing performed by the phase difference AF unit 129 and the TVAF unit 130 will be described in more detail. First, the configuration of the image sensor 122 will be described. FIG. 3A shows a pixel arrangement in a range of 6 rows in the vertical direction (Y direction) and 8 columns in the horizontal direction (X direction) of the imaging device 122 as a two-dimensional C-MOS area sensor as viewed from the imaging optical system side. Yes. The image sensor 122 is provided with a Bayer array color filter, and the odd-numbered pixels 211 are alternately provided with green (G) and red (R) color filters in order from the left. Are provided with blue (B) and green (G) color filters alternately from the left. 211i drawn in a circle indicates an on-chip microlens (hereinafter simply referred to as a microlens). 211a and 211b drawn in two rectangles inside the micro lens 211i are photoelectric conversion units.

  In all the pixels 211, the photoelectric conversion units 211a and 211b are divided into two in the X direction, and the photoelectric conversion signal output from one of the two divided photoelectric conversion units 211a and 211b and the photoelectric conversion output from both of them. The sum of the signals can be read out independently. By subtracting the photoelectric conversion signal from one photoelectric conversion unit from the sum of the photoelectric conversion signals from both photoelectric conversion units 211a and 211b, a signal corresponding to the photoelectric conversion signal output from the other photoelectric conversion unit is obtained. Can do. The one and the other photoelectric conversion signals are used for generating a pair of phase difference image signals (images for phase difference AF) in imaging plane phase difference AF, as well as calculating a subject distance and generating a pair of parallax images having parallax with each other. Also used for. The sum of both photoelectric conversion signals is used as an imaging signal for generating a TVAF image and a normal captured image.

  Here, generation of a phase difference image signal paired with the pupil division function of each pixel 211 as a focus detection pixel used in phase difference AF will be described. In each pixel 211, the photoelectric conversion units 211a and 211b are arranged so as to be biased toward different sides in the X direction with respect to the microlens 211i. For this reason, the photoelectric conversion units 211a and 211b receive light beams from different regions of the exit pupil of the imaging optical system through which light beams from the same region of the subject pass through the microlenses 211i. Thereby, pupil division is performed.

  In addition, a signal generated by connecting the photoelectric conversion signals from the photoelectric conversion units 211a of the plurality of pixels 211 within a predetermined range arranged in the same row is used as an A image signal, and the photoelectric conversion signals from the photoelectric conversion unit 211b are connected. The signal generated together is defined as a B image signal. As described above, the photoelectric conversion signal from the photoelectric conversion unit 211b is a signal obtained by subtracting the photoelectric conversion signal from the photoelectric conversion unit 211a from the sum of the photoelectric conversion signals from the photoelectric conversion units 211a and 211b. These A image signal and B image signal are a pair of phase difference image signals. The A image and B image signals may be generated by connecting pseudo luminance signals obtained by adding photoelectric conversion signals from four RGGB pixels included in one Bayer array unit of the color filter. However, it may be generated by connecting photoelectric conversion signals for each RGB color.

  By performing a correlation operation on the A image signal and the B image signal generated in this way, a phase difference that is a relative shift amount between the A image signal and the B image signal can be calculated. The focus detection of the phase difference detection method, that is, phase difference AF can be performed by calculating the defocus amount of the subject image (that is, the imaging optical system) formed on the image sensor 122 from the phase difference. it can.

  In the present embodiment, the outputs from a plurality of pixels within the predetermined range are added by the method described later for the purpose of reducing the computation load, improving the S / N of the phase difference image signal, and adjusting the output image size. To generate A image and B image signals.

  FIG. 3B illustrates a configuration of a reading unit provided in the image sensor 122. 151 is a horizontal scanning circuit, and 153 is a vertical scanning circuit. Between each pixel, horizontal scanning lines 152a and 152b and vertical scanning lines 154a and 154b are wired, and photoelectric conversion signals from the respective photoelectric conversion units are passed through these scanning lines through the horizontal scanning circuit 151 and the vertical scanning circuit 153. Is read.

  FIG. 4A shows the conjugate relationship between the exit pupil 102 of the imaging optical system and the photoelectric conversion units 211a and 211b of the pixel 211 disposed near the image height 0 (near the center of the image plane) of the imaging element 122. ing. The exit pupil 102 and the photoelectric conversion units 211a and 211b have a conjugate relationship by the microlens 211i. In general, the position of the exit pupil (exit pupil plane) of the imaging optical system substantially coincides with the plane on which the iris diaphragm for adjusting the light amount (for example, the diaphragm 102 shown in FIG. 2) is arranged. In a zoom lens having a zooming function like the imaging optical system of the interchangeable lens 100 shown in FIG. 2, the distance of the exit pupil 102 from the image plane (hereinafter referred to as the exit pupil distance) and the size of the exit pupil 102 by zooming. May change. The imaging optical system shown in FIG. 4A shows a state where the focal length is intermediate between the wide angle end and the telephoto end. Assuming this as a standard exit pupil distance Zep, the eccentric parameter of the microlens 211i is set in accordance with the shape and image height (X, Y coordinates) of the microlens 211i.

  4A, reference numeral 101 denotes a first lens group included in the imaging optical system, and reference numeral 101b denotes a lens barrel member that holds the first lens group 101. Reference numeral 105 denotes a third lens group, and reference numeral 105 b denotes a lens barrel member that holds the third lens group 105. In the diaphragm 102, 102 a is an aperture plate that sets an open aperture diameter of the diaphragm 102. Reference numeral 102 b denotes a diaphragm blade for adjusting the aperture diameter of the diaphragm 102. The lens barrel member 101b, the aperture plate 102a, the aperture blade 102b, and the lens barrel member 105b, which act as limiting members that limit the light beam passing through the imaging optical system, show optical virtual images when viewed from the image plane. The synthetic aperture in the vicinity of the stop 102 is defined as the exit pupil 102 of the imaging optical system, and the distance from the exit pupil 102 to the image plane is defined as the exit pupil distance Zep described above.

  As shown in FIG. 4A, in the pixel 211, photoelectric conversion units 211a and 211b, a plurality of wiring layers 211e to 211g, a color filter 211h, and a microlens 211i are arranged in this order from the bottom layer side. Configured. The two photoelectric conversion units 211a and 211b are projected onto the exit pupil plane of the imaging optical system by the microlens 211i. In other words, the exit pupil 102 of the imaging optical system is projected onto the surfaces of the photoelectric conversion units 211a and 211b via the microlens 211i.

  FIG. 4B shows projection images EP1a and EP1b of the photoelectric conversion units 211a and 211b on the exit pupil plane of the imaging optical system. In FIG. 4A, if the outermost light beam group among the light beams passing through the imaging optical system is L, the outermost light beam group L is limited by the aperture plate 102 a of the stop 102. In FIG. 4B, the outermost ray group L is indicated by TL. Since most of the projection images EP1a and EP1b of the photoelectric conversion units 211a and 211b are included inside the circle indicated by TL, the projection images EP1a and EP1b may hardly have vignetting due to the imaging optical system. I understand. Since the outermost ray group TL is limited only by the aperture plate 102a of the diaphragm 102, the diameter of the outermost ray group TL corresponds to the aperture diameter of the aperture plate 102a. At this time, slight vignetting of the projected images EP1a and EP1b occurs symmetrically with respect to the optical axis in the vicinity of the center of the image plane, so that the light amounts received by the photoelectric conversion units 211a and 211b are equal.

  The camera MPU 125 that performs phase difference AF is sensor-driven so that the photoelectric conversion signal output from one of the photoelectric conversion units 211a and 211b described above from the image sensor 122 and the sum of the photoelectric conversion signals output from both are read out. The circuit 123 is controlled. The camera MPU 125 gives information about the position and size of the focus detection area within the imaging range to the image processing circuit 124. Then, the image processing circuit 124 generates A image and B image signals (phase difference AF images) using the photoelectric conversion signals of the pixels included in the focus detection region, and supplies the A image and B image signals to the phase difference AF unit 129. Instruct. The focus detection area will be described later. In accordance with this instruction, the image processing circuit 124 generates A image and B image signals and outputs them to the phase difference AF unit 129. The image processing circuit 124 generates a RAW image as a TVAF image and supplies the RAW image to the TVAF unit 130.

  Here, as an example, the case where the photoelectric conversion unit in one pixel is divided into two in the horizontal direction and the exit pupil is divided into two in the horizontal direction is shown, but the photoelectric conversion unit in one pixel of a part of the imaging element is shown. The exit pupil may be divided into two in the vertical direction by dividing into two in the vertical direction. Further, four photoelectric conversion units divided into two in the horizontal and vertical directions may be provided in one pixel, and the exit pupil may be divided in the horizontal and vertical directions. By performing pupil division also in the vertical direction, phase difference AF using the contrast of the subject in the vertical direction as well as the horizontal direction can be performed.

  Next, contrast AF (TVAF) will be described with reference to FIG. In TVAF, the camera MPU 125 and the TVAF unit 130 cooperate to repeatedly drive the focus lens 104 and calculate a contrast evaluation value (hereinafter referred to as AF evaluation value). When a RAW image is input from the image processing circuit 124 to the TVAF unit 130, the AF evaluation signal processing circuit 401 suppresses the high luminance component by extracting the G signal and enhancing the low luminance component with respect to the RAW image. Perform gamma correction processing. In this embodiment, the case where TV AF is performed using a G signal will be described, but all RGB signals may be used. Alternatively, a signal obtained by adding all RGB signals may be used. In any of these cases, a signal generated by the AF evaluation signal processing circuit 401 is referred to as a luminance signal Y in the following description.

  The camera MPU 125 sets the position and size of the focus detection area with respect to the area setting circuit 413. The area setting circuit 413 generates a gate signal for selecting a photoelectric conversion signal in the set focus detection area. The gate signal is input to each of the line peak detection circuit 402, the horizontal integration circuit 403, the line minimum value detection circuit 404, the line peak detection circuit 409, the vertical integration circuits 406 and 410, and the vertical peak detection circuits 405, 407, and 411. . In addition, the camera MPU 125 controls the timing at which the luminance signal Y is input to each circuit so that various AF evaluation values described below are generated using the luminance signal Y obtained in the focus detection area. To do. The area setting circuit 413 may set a plurality of focus detection areas. Hereinafter, a method for generating a Y peak evaluation value, an Y integral evaluation value, a Max-Min evaluation value, an all-line integral evaluation value, and a region peak evaluation value as AF evaluation values will be described. First, a method for calculating the Y peak evaluation value will be described. The gamma-corrected luminance signal Y is input to the line peak detection circuit 402, where the Y line peak value, which is the peak value of the luminance signal Y for each horizontal line in the focus detection area set in the area setting circuit 413, is obtained. It is done. The output of the line peak detection circuit 402 is peak-held in the vertical direction within the focus detection area in the vertical peak detection circuit 405, thereby generating a Y peak evaluation value. The Y peak evaluation value is an effective index for determining a high brightness subject or a low illumination subject.

  A method for calculating the Y integral evaluation value will be described. The gamma-corrected luminance signal Y is input to the horizontal integration circuit 403, and an integrated value of the luminance signal Y is obtained for each horizontal line in the focus detection area. Then, the output of the horizontal integration circuit 403 is integrated in the vertical direction within the focus detection area by the vertical integration circuit 406, thereby generating a Y integration evaluation value. The Y integral evaluation value is used as an index for determining the brightness of the entire focus detection area.

  A method for calculating the Max-Min evaluation value will be described. The gamma-corrected luminance signal Y is input to the line peak detection circuit 402, where the Y line peak value, which is the peak value of the luminance signal Y for each horizontal line in the focus detection area, is obtained. Also, the luminance signal Y subjected to gamma correction is input to the line minimum value detection circuit 404, where the minimum value of the luminance signal Y is detected for each horizontal line in the focus detection area. The detected Y line peak value and minimum value for each horizontal line are input to the subtractor (−), and (Y line peak value−minimum value) are input to the vertical peak detection circuit 407. The vertical peak detection circuit 407 generates a Max-Min evaluation value by performing peak holding (Y line peak value−minimum value) in the vertical direction within the focus detection region. The Max-Min evaluation value is an effective index for determining low contrast and high contrast.

  A method for calculating the region peak evaluation value will be described. The gamma-corrected luminance signal Y passes through the BPF 408, so that a specific frequency component is extracted and a contrast signal is generated. This contrast signal is input to the line peak detection circuit 409, where a line peak value which is the peak value of the contrast signal for each horizontal line in the focus detection area is obtained. The line peak value is peak-held in the focus detection area by the vertical peak detection circuit 411, thereby generating an area peak evaluation value. Since the area peak evaluation value changes little even if the subject moves within the focus detection area, it is determined whether or not to shift from the focused state to the process of searching for the position of the focus lens 104 where the focused state is obtained again. This is an effective index for restart determination.

  A method for calculating the total line integral evaluation value will be described. Similar to the area peak evaluation value, the line peak detection circuit 409 obtains the line peak value of the contrast signal for each horizontal line in the focus detection area. Next, the line peak value is input to the vertical integration circuit 410, where the line peak value is integrated with respect to the total number of horizontal scanning lines in the vertical direction within the focus detection area to generate an all-line integration evaluation value. The high-frequency all-line integral evaluation value is used as a main AF evaluation value because the integration effect has a wide dynamic range and high sensitivity.

  The TVAF unit 130 moves the focus lens 104 by a predetermined amount in a specific direction in the optical axis direction through the camera MPU 125 and the lens MPU 117 based on the respective AF evaluation values described above. Then, the above-described AF evaluation value is acquired based on the newly obtained TVAF image, and the position of the focus lens 104 at which the total line integration evaluation value becomes the maximum value is detected.

  In this embodiment, the various AF evaluation values described above are calculated in the horizontal line direction and the vertical line direction, respectively, and TVAF based on the contrast of the subject is performed in these two directions orthogonal to each other.

  FIG. 6 shows a focus detection area 219 that is set to include a part of the subject 220 in the imaging range. Both the phase difference AF and TVAF are performed based on a photoelectric conversion signal obtained from a pixel included in the focus detection area 219 in the image sensor 122. Note that the position, size, and number of the focus detection areas 219 in the imaging range can be different from the example shown in FIG.

  Next, AF processing performed by the camera MPU 125, the phase difference AF unit 129, and the TVAF unit 130 will be described with reference to the flowcharts of FIGS. The camera MPU 125, the phase difference AF unit 129, and the TVAF unit 130 execute this processing according to a focus control program that is a computer program.

  In step S1 of FIG. 1A, the camera MPU 125 sets the position and size of the focus detection area 219 so as to include a specific subject such as the face of the person 220 as shown in FIG. To do. At this time, the camera MPU 125 sets the representative coordinates (x1, y1) as the position of the focus detection area 219. The representative coordinates (x1, y1) may be the center of the focus detection area 219 or the position of the center of gravity.

  Next, in step S2, the camera MPU 125 acquires parameters (calculation conditions) necessary for calculating a best focus (BP) correction value described later. The BP correction value includes the focus position, which is the position of the focus lens 104, the zoom position, which is the position of the first lens group 101, the representative coordinates (x1, y1) of the focus detection area, and the state of the imaging optical system and the focus detection area. It changes according to the position. Therefore, the camera MPU 125 acquires information on the focus position and the zoom position from the lens MPU 117 in step S2, and also acquires information on the representative coordinates of the focus detection area (hereinafter referred to as the position of the focus detection area) (x1, y1). To do.

  Next, in step S3, the camera MPU 125 acquires BP correction information corresponding to the aberration information of the imaging optical system from the lens MPU 117. Specifically, the BP correction information is information indicating the position of the focus lens 104 (or the imaging position of the imaging optical system) from which the in-focus state for each color, direction (horizontal and vertical direction) and spatial frequency of the subject is obtained. It is. The BP correction information is stored in the lens memory 118 in advance.

  An example of BP correction information will be described with reference to FIGS. FIG. 7A shows the defocus MTF of the imaging optical system. The horizontal axis indicates the position (defocus amount) of the focus lens 104, and the vertical axis indicates the intensity of the MTF. The four curves show the defocus MTF for each spatial frequency, and are MTF1, MTF2, MTF3, and MTF4 in order from the lowest spatial frequency. Specifically, the defocus MTF at the spatial frequency F1 (lp / mm) is MTF1, and similarly, the defocus MTF at the spatial frequencies F2, F3, and F4 (lp / mm) is MTF2, MTF3, and MTF4. It is. LP4, LP5, LP5, and LP6 respectively indicate positions of the focus lens 104 (hereinafter referred to as MTF peak positions) at which the maximum values of MTF1, MTF2, MTF3, and MTF4 are obtained, that is, a focused state is obtained. .

  FIG. 7B shows changes in the spatial frequency of the MTF peak position MTF_P, which is BP correction information, for each color (R, G, B) and evaluation direction (H, V) of the subject. The horizontal axis represents the spatial frequency, and Nq represents the Nyquist frequency determined by the pixel pitch of the image sensor. The vertical axis represents the MTF peak position.

  As shown in the figure, when the chromatic aberration of the imaging optical system is large, the MTF peak position for each color deviates, and when the contrast difference in the evaluation direction is large, the MTF peak position for each evaluation direction deviates. As described above, in this embodiment, information on the MTF peak position with respect to the spatial frequency is included as BP correction information for each combination of color and evaluation direction.

The MTF peak position MTF_P is the spatial frequency f and the position (x1, y1) of the focus detection area (x (y)) for each of the six combinations of the subject color (R, G, B) and the evaluation direction (H, V). x, y)) is a variable and is expressed by the following equation (1). However, Expression (1) represents the MTF peak position MTF_P_RH for the R color and the horizontal (H) direction as a representative. _RH added after MTF_P means the R color and the H direction, and (f, x, y) indicates a function of f and (x, y). The MTF peak position MTF_P_RV for the R color and the vertical (V) direction, the MTF peak position MTF_P_GH for the G color and the H direction, and the MTF peak position MTF_P_GV for the G color and the V direction are also expressed by the same expression. Further, the MTF peak position MTF_P_BH for the B color and the H direction and the MTF peak position MTF_P_BV for the B color and the V direction are also expressed by the same expression.
MTF_P_RH (f, x, y)
= (rh (0) × x + rh (1) × y + rh (2)) × f ² + (rh (3) × x + rh (4) × y + rh (5)) × f + (rh ( 6) × x + rh (7) × y + rh (8)) (1)
Rh (n) (0 ≦ n ≦ 8) included in each frequency term in Expression (1) indicates a coefficient for the R color and the H direction, and is stored in the lens memory 118 in advance. The camera MPU 125 requests the lens MPU 117 to transmit the coefficient rh (n) and acquires it. However, rh (n) may be stored in a non-volatile area of the RAM 125b in the camera MPU 125 and acquired by the camera MPU 125 reading it. The MTF peak positions MTF_P_RV, MTF_P_GH, MTF_P_GV, MTF_P_BH and MTF_P_BV also include coefficients rv (n), gh (n), gv (n), bh (n) and bv (n), respectively. Are obtained in the same manner as rh (n).

  In this embodiment, the BP correction information is expressed by a function, and the coefficient in the function is stored in the lens memory 118 or the RAM 125b. This makes it possible to prepare BP correction information corresponding to the zoom position and aperture value of the imaging optical system while reducing the amount of data stored in the lens memory 118 and the RAM 125b.

  Next, in step S4, the camera MPU 125 acquires focus evaluation information. FIG. 8A shows an example of focus evaluation information (K_AF, K_IMG) set for focus detection (AF) and captured image evaluation. The focus evaluation information is information on a weighting coefficient indicating the weighting level of BP correction information (MTF peak position) for a combination of evaluation direction (H, V), subject color (R, G, B) and spatial frequency. . Details of the processing performed by the camera MPU 125 in this step will be described later.

Next, in step S5, the camera MPU 125 calculates (acquires) a BP correction value using the weighting coefficient as the focus evaluation information acquired in step S4 and the BP correction information acquired in step S3. First, the camera MPU 125 substitutes the position (x1, y1) of the focus detection region for x, y in Expression (1), which is a function representing the MTF peak position, and sets the coefficients of the three frequency terms as Arh, Brh, Crh, respectively. Therefore, the expression (1) is expressed by the following expression (2).
MTF_P_RH (f) = Arh × f ² + Brh × f + Crh (2)
The same applies to the MTF peak position functions MTF_P_RV, MTF_P_GH, MTF_P_GV, MTF_P_BH and MTF_P_BV for other colors and directions. FIG. 7B described above shows the MTF peak position after substituting the position of the focus detection area into Equation (1).

Further, the camera MPU 125 weights the MTF peak position as the BP correction information by the weighting coefficient as the focus evaluation information acquired in step S4. As a result, the MTF peak positions for focus detection and captured image evaluation are weighted according to the evaluation direction and the color of the subject. Specifically, camera MPU 125 calculates MTF peak position MTF_P_AF for focus detection and MTF peak position MTF_P_IMG for captured image evaluation using equations (3) and (4).
MTF_P_AF (f)
= K_AF_R × K_AF_H × MTF_P_RH (f) + K_AF_R × K_AF_V × MTF_P_RV (f)
+ K_AF_G × K_AF_H × MTF_P_GH (f) + K_AF_G × K_AF_V × MTF_P_GV (f)
+ K_AF_B × K_AF_H × MTF_P_BH (f) + K_AF_B × K_AF_V × MTF_P_BV (f) (3)
MTF_P_IMG (f)
= K_IMG_R × K_IMG_H × MTF_P_RH (f) + K_IMG_R × K_IMG_V × MTF_P_RV (f)
+ K_IMG_G × K_IMG_H × MTF_P_GH (f) + K_IMG_G × K_IMG_V × MTF_P_GV (f)
+ K_IMG_B × K_IMG_H × MTF_P_BH (f) + K_IMG_B × K_IMG_V × MTF_P_BV (f) (4)
In Expression (3), K_AF_R, K_AF_G, and K_AF_B indicate weighting coefficients for each color (R, G, B) at the time of focus detection, and K_IMG_R, K_IMG_G, and K_IMG_B indicate weighting coefficients for each color at the time of evaluation of the captured image. In Equation (4), K_AF_H and K_AF_V indicate weighting coefficients for each evaluation direction (H, V) at the time of focus detection, and K_IMG_H and K_IMG_V indicate weighting coefficients for each evaluation direction at the time of captured image evaluation.

FIG. 8B shows focus detection MTF peak positions (vertical axes) LP4_AF, LP5_AF, LP6_AF obtained from equations (3) and (4) for discrete spatial frequencies (horizontal axes) F1 to F4. LP7_AF is shown. Subsequently, the camera MPU 125 calculates the captured image focus position P_IMG, which is the position of the focus lens 104 from which the captured image in the focused state is obtained, using the following equation (5). Further, the camera MPU 125 calculates an AF in-focus position P_AF, which is the position of the focus lens 104 at which an in-focus state is obtained in AF, using the following formula (6). For these calculations, the MTF peak positions MTF_P_IMG and MTF_P_AF obtained in step S3 and the weighting coefficients K_IMG_FQ and K_AF_FQ obtained in step S4 are used.
P_IMG
= MTF_P_IMG (1) × K_IMG_FQ1 + MTF_P_IMG (2) × K_IMG_FQ2
+ MTF_P_IMG (3) × K_IMG_FQ3 + MTF_P_IMG (4) × K_IMG_FQ4 (5)
P_AF
= MTF_P_AF (1) × K_AF_FQ1 + MTF_P_AF (2) × K_AF_FQ2
+ MTF_P_AF (3) × K_AF_FQ3 + MTF_P_AF (4) × K_AF_FQ4 (6)
That is, the camera MPU 125 uses the MTF peak position MTF_P_IMG for each captured image evaluation spatial frequency shown in FIG. 8B and the weighted coefficient K_IMG_FQ for each captured image evaluation spatial frequency shown in FIG. To add weights. Similarly, the camera MPU 125 weights and adds MTF_P_AF for each spatial frequency for focus detection shown in FIG. 8B using the weighting coefficient K_AF_FQ for each spatial frequency for focus detection shown in FIG. 8A. To do. Thereby, the captured image focus position (P_IMG) and the AF focus position (P_AF) are calculated.

  Next, the camera MPU 125 calculates a BP correction value (BP) by the following equation (7).

BP = P_AF−P_IMG (7)
P_AF has, as variables FQ1 to FQ4, an AF evaluation band (second evaluation band) that is a spatial frequency at which the focus state is evaluated during focus detection. P_IMG has an image evaluation band (first evaluation band), which is a spatial frequency at which the focus state is evaluated during evaluation of the captured image, as variables FQ1 to FQ4. That is, the BP correction value includes the AF evaluation band and the image evaluation band as variables.

  Next, the focus evaluation information acquisition process in step S4 will be described using the flowchart shown in FIG. As described above, FIG. 8A shows the focus evaluation information (weighting coefficient) for the evaluation direction, color, and spatial frequency.

  From the viewpoint of focusing accuracy, it is desirable to use optimum focus evaluation information in accordance with various information related to the subject. However, in order to analyze various information related to the subject, a lot of processing time is required. As a method for easily calculating a BP correction value, there is a method for calculating a BP correction value that does not depend on a subject by always using optimum focus evaluation information when a specific scene is imaged. However, there may be image blur due to subject movement, camera shake, zoom operation of the interchangeable lens 100, or the like in the captured image or focus detection image, and a decrease in spatial frequency caused by the image blur causes a focus detection error. Cause it to occur. In the present embodiment, the focus detection accuracy is improved by lowering the spatial frequency at the time of calculating the BP correction value when the exposure time in which such an image blur is likely to occur is long.

  As described above, the weighting coefficient as the focus evaluation information differs depending on the combination of the evaluation state of the focus state, the color of the subject, and the spatial frequency. FIG. 8A shows the weighting coefficients for the four spatial frequencies for both the focus detection and the captured image. In this embodiment, the BP correction value is calculated by the weighted average of the four spatial frequencies.

  FIG. 9 shows the relationship between the weighting coefficient K_AF_FQ at the spatial frequency at the time of focus detection, the weighting coefficient K_IMG_FQ at the spatial frequency of the captured image, and the four spatial frequencies FQ1 to FQ4. The intensity on the vertical axis indicates the magnitude of the weighting coefficient. Since the evaluation band which is a spatial frequency for evaluating the focus state is different between the focus detection and the captured image, K_AF_FQ and K_IMG_FQ at the spatial frequencies FQ1 to FQ4 are different. In FIG. 1B, in step S101, the camera MPU 125 acquires an exposure time set for focus detection (AF) (hereinafter referred to as AF exposure time).

  In step S102, the camera MPU 125 determines whether or not the AF exposure time is longer than a predetermined value (second predetermined time) TV0. If the AF exposure time is longer than the predetermined value TV0, K_AF_FQ_0 is acquired as K_AF_FQ in step S103. If the AF exposure time is shorter than the predetermined value TV0, K_AF_FQ_1 is acquired as K_AF_FQ in step S104. K_AF_FQ_0 and K_AF_FQ_1 are each composed of weighting coefficients at the four spatial frequencies FQ1 to FQ4.

  In this embodiment, when the AF exposure time is long, the AF evaluation band is lowered. Therefore, the weighted average spatial frequency obtained by multiplying the spatial frequency FQ1 to FQ4 by the weighting coefficient indicated by K_AF_FQ_0 is lower than the weighted average spatial frequency obtained by multiplying the spatial frequency FQ1 to FQ2 by the weighting coefficient indicated by K_AF_FQ_1.

  Next, in step S105, the camera MPU 125 acquires a first exposure time (hereinafter referred to as an imaging exposure time) set for imaging (for a captured image). If the imaging exposure time is longer than the predetermined value (first predetermined time) TV0, K_IMG_FQ_0 is acquired as K_IMG_FQ in step S106. If the imaging exposure time is shorter than the predetermined value TV0, K_IMG_FQ_1 is acquired as K_IMG_FQ in step S107. K_IMG_FQ_0 and K_IMG_FQ_1 are each composed of weighting coefficients in the four spatial frequencies FQ1 to FQ4.

  The present embodiment is characterized in that the image evaluation band is made lower when the imaging exposure time is long. Therefore, the weighted average spatial frequency obtained by multiplying the spatial frequency FQ1 to FQ4 by the weighting coefficient indicated by K_IMG_FQ_0 is lower than the weighted average spatial frequency obtained by multiplying the spatial frequency FQ1 to FQ2 by the weighting coefficient indicated by K_IMG_FQ_1.

  In order to calculate BP at the time of AF, it is desirable that AF AE and photographing AE are performed at the same time when AF is performed, and AF exposure conditions and photographing exposure conditions are determined simultaneously.

Further, the predetermined value TV0 may be a fixed value, but the above-described image blur occurs more greatly as the focal length of the imaging optical system is longer.
TV0 = 1 / FL [sec]
May be set.

  The camera MPU 125 that has acquired K_AF_FQ and K_IMG_FQ in this way calculates the BP correction value (BP) using the spatial frequency as a variable using the equations (5) to (7) as described above.

In addition to the spatial frequency, the focus evaluation information can be made different depending on the evaluation direction and the color of the subject, but here, the focus evaluation information for the evaluation direction and the color is a fixed value and does not depend on the subject. As an example of the fixed value, the weighting coefficients K_AF_H, K_AF_V, K_IMG_H, and K_IMG_V for the evaluation direction are as follows when the pupil division direction is only the horizontal direction as shown in FIG.
K_AF_H = 1
K_AF_V = 0
K_IMG_H = 1
K_IMG_V = 1
May be set. This is because focus detection (AF) is greatly influenced by aberrations in the horizontal direction, and the captured image is generally judged to be in a focus state based on an aberration state in which horizontal aberrations and vertical aberrations are averaged by 1: 1. This is because.

The weighting coefficients K_AF_R, K_AF_G, K_AF_B, K_IMG_R, K_IMG_G, and K_IMG_B for colors are, for example, when the focus detection pixel is only G in the Bayer array,
K_AF_R = 0
K_AF_G = 1
K_AF_B = 0
K_IMG_R = 0.3
K_IMG_G = 0.5
K_IMG_B = 0.2
May be set. This is because only the chromatic aberration of G influences the focus detection, and the focus state fluctuates in the captured image due to the influence of chromatic aberration for each color weighted by a desired white balance coefficient.

  By dividing the spatial frequency band (evaluation band) for evaluating the focus state according to the exposure time as in this embodiment, it is possible to suppress the occurrence of focus detection error due to the influence of image blur and improve the focus detection accuracy. . In this embodiment, the spatial frequency band is divided with the predetermined value TV0 as a boundary at the time of imaging and at the time of AF, but the first and second predetermined times are used as predetermined values different at the time of imaging and at the time of AF. Also good. In this embodiment, the spatial frequency band is divided into two with one exposure time (predetermined value TV0) as a boundary. However, the spatial frequency band is divided into three or more with two or more exposure times as a boundary. Also good.

  In the first embodiment, the case has been described in which the image evaluation band for evaluating the focus state is changed during the evaluation of the captured image according to the imaging exposure time. On the other hand, in the second embodiment of the present invention, the relationship with the AF evaluation band is obtained by changing the image evaluation band based on the shake amount of the image pickup optical system (image pickup apparatus), in other words, the image shake amount on the image plane. Adjust. Since the method other than the method for determining the image evaluation band is the same as that of the first embodiment, the common description is omitted here. In addition, constituent elements common to the first embodiment are denoted by the same reference numerals as in the first embodiment.

  As a method for detecting image shake, there are a method using a shake sensor such as a vibration gyroscope (angular velocity sensor), a method for detecting a motion vector between frame images sequentially generated in moving image capturing, and the like. In the present embodiment, the image evaluation band, in other words, the weighting coefficient as the first focus evaluation information is determined according to the image blur amount detected using any one of these methods.

  The focus evaluation information acquisition process performed by the camera MPU 125 in this embodiment will be described with reference to the flowchart of FIG. In step S201, the camera MPU 125 acquires an imaging exposure time. In step S202, it is determined whether the imaging exposure time is longer than a predetermined value TV0.

  If the imaging exposure time is shorter than the predetermined value TV0, the camera MPU 125 acquires K_IMG_FQ_1 as K_IMG_FQ in step S206. When the imaging exposure time is longer than the predetermined value TV0, the camera MPU 125 proceeds to step S203, and determines whether or not the detected image blur amount (first image blur amount) at the time of imaging is larger than the predetermined value X. .

  If the image blur amount is larger than the predetermined value (first predetermined amount) X, the camera MPU 125 acquires K_IMG_FQ_00 as K_IMG_FQ in step S204. If the image blur amount is smaller than the predetermined value X, K_IMG_FQ_01 is acquired as K_IMG_FQ in step S205.

K_IMG_FQ_00, K_IMG_FQ_01 and K_IMG_FQ_1 are respectively obtained by multiplying the weighting coefficients indicated by K_IMG_FQ_00, K_IMG_FQ_01 and K_IMG_FQ_1, which are weighting coefficients at the above four spatial frequencies FQ1 to FQ4, by the spatial frequency FQ1 to FQ4 and the weighted average frequency. There is.
K_IMG_FQ_00 <K_IMG_FQ_01 <K_IMG_FQ_1
This means that when the imaging exposure time is short, the image evaluation band is high because the influence of image blur is small. Further, when the imaging exposure time is long and the image blur amount is large, it is considered that the spatial frequency of the subject is biased toward the low frequency side, which means that the image evaluation band is set to the low frequency side.

In the present embodiment, the case where the image evaluation band is changed according to the image blur amount has been described. Similarly, the AF evaluation band is changed according to the image blur amount (second image blur amount) at the time of focus detection. Also good. That is, the camera MPU 125 acquires K_AF_FQ_00 as K_AF_FQ when the image blur amount is larger than the predetermined value (second predetermined amount) X. When the image blur amount is smaller than the predetermined value X, K_AF_FQ_01 is acquired as K_AF_FQ. K_AF_FQ_00, K_AF_FQ_01, and K_AF_FQ_1 are weighting coefficients for the four spatial frequencies FQ1 to FQ4, respectively. When the weighted average spatial frequencies obtained by multiplying the weighting coefficients indicated by K_AF_FQ_00, K_AF_FQ_01, and K_AF_FQ_1 by the spatial frequencies FQ1 to FQ4 are compared, there is the following relationship.
K_AF_FQ_00 <K_AF_FQ_01 <K_AF_FQ_1
This means that when the AF exposure time is short, the influence of image blur is small and the AF evaluation band is high. Further, when the AF exposure time is long and the image blur amount is large, it is considered that the spatial frequency of the subject is biased toward the low frequency side, which means that the AF evaluation band is set to the low frequency side.

  In this embodiment, the evaluation band is changed between two frequency bands with one image blur amount (predetermined value X) as a boundary, but the evaluation band is three or more frequency bands with two or more image blur amounts as a boundary. You may change between. Further, the predetermined value X for the captured image and the predetermined value for focus detection may be the same value or different values. Furthermore, the image shake amount for the captured image may be predicted (estimated) by a known prediction method.

In each of the above embodiments, the interchangeable lens digital camera has been described. However, the present invention includes a lens integrated digital camera and a video camera as embodiments. An imaging device in a broad sense such as a mobile phone equipped with a camera, a personal computer, or a game machine is also included in the embodiments of the present invention.
(Other examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

120 imaging device 125 camera MPU
129 Phase difference AF unit

Claims (9)

Focus detection means for generating focus detection information by detecting the focus state of the imaging optical system;
Correction value acquisition means for acquiring a correction value for correcting the focus detection information;
Control means for performing focus control using the focus detection information corrected by the correction value;
The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated,
The first evaluation band when the first exposure time that is the exposure time at the time of imaging is longer than a first predetermined time is the first evaluation band when the first exposure time is shorter than the first predetermined time. An imaging apparatus characterized by being lower than an evaluation band of 1.   The imaging apparatus according to claim 1, wherein the correction value acquisition unit changes the first predetermined time according to a focal length of the imaging optical system. The correction value includes, as a variable, a second evaluation band that is a spatial frequency at which the focus state of the imaging optical system is evaluated by the focus detection unit,
The second evaluation band when the second exposure time that is the exposure time at the time of detecting the focus state is longer than a second predetermined time is when the second exposure time is shorter than the second predetermined time The imaging apparatus according to claim 1, wherein the imaging apparatus is lower than the second evaluation band. Focus detection means for generating focus detection information by detecting the focus state of the imaging optical system;
Correction value acquisition means for acquiring a correction value for correcting the focus detection information;
Control means for performing focus control using the focus detection information corrected by the correction value;
The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated,
The first evaluation band when the first image blur amount, which is the image blur amount at the time of imaging, is larger than the first predetermined amount, is the case where the first image blur amount is smaller than the first predetermined amount. An imaging apparatus characterized by being lower than the first evaluation band. The correction value includes, as a variable, a second evaluation band that is a spatial frequency at which the focus state of the imaging optical system is evaluated by the focus detection unit,
In the second evaluation band when the second image blur amount, which is the image blur amount at the time of detecting the focus state, is larger than a second predetermined value, the second image blur amount is the second predetermined amount. The imaging apparatus according to claim 4, wherein the imaging device is lower than the second evaluation band in the case of being smaller. A method for controlling an imaging apparatus having focus detection means for detecting focus state of an imaging optical system and generating focus detection information,
Obtaining a correction value for correcting the focus detection information;
Performing focus control using the focus detection information corrected by the correction value,
The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated,
The first evaluation band when the first exposure time that is the exposure time at the time of imaging is longer than a first predetermined time is the first evaluation band when the first exposure time is shorter than the first predetermined time. A control method for an imaging apparatus, characterized by being lower than an evaluation band of 1. A method for controlling an imaging apparatus having focus detection means for detecting focus state of an imaging optical system and generating focus detection information,
Obtaining a correction value for correcting the focus detection information;
Performing focus control using the focus detection information corrected by the correction value,
The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated,
The first evaluation band when the first image blur amount, which is the image blur amount at the time of imaging, is larger than the first predetermined amount, is the case where the first image blur amount is smaller than the first predetermined amount. A control method for an imaging apparatus, characterized by being lower than the first evaluation band. In a computer of an imaging apparatus having focus detection means for detecting focus state of the imaging optical system and generating focus detection information,
Obtaining a correction value for correcting the focus detection information;
A computer program that executes processing including a step of performing focus control using the focus detection information corrected by the correction value,
The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated,
The first evaluation band when the first exposure time that is the exposure time at the time of imaging is longer than a first predetermined time is the first evaluation band when the first exposure time is shorter than the first predetermined time. A focus control program characterized by being lower than one evaluation band. In a computer of an imaging apparatus having focus detection means for detecting focus state of the imaging optical system and generating focus detection information,
Obtaining a correction value for correcting the focus detection information;
A computer program that executes processing including a step of performing focus control using the focus detection information corrected by the correction value,
The correction value includes, as a variable, a first evaluation band that is a spatial frequency at which a focus state of a captured image generated by imaging using the imaging optical system is evaluated,
The first evaluation band when the first image blur amount, which is the image blur amount at the time of imaging, is larger than the first predetermined amount, is the case where the first image blur amount is smaller than the first predetermined amount. A focus control program characterized by being lower than the first evaluation band.