JP2016194665A - Focus detection device, optical instrument, focus detection program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform focus detection using a phase difference detection method properly even if a perspective conflict occurs in a subject.SOLUTION: A focus detection device 204 calculates a detection amount which is either one of a phase difference in a pair of image signals obtained from a focus detection area of an image pick-up device 201 imaging a subject image formed by a photographic optical system, and a defocus amount of the photographic optical system based on the phase difference. The device is provided with a plurality of first areas 1-9 in the focus detection area, and comprises: first calculation means 204 for calculating a detection amount for each of the first areas; reference setting means 213 for selecting a reference area 5 from the plurality of first areas and setting a detection amount of the reference area as reference detection amount; and second calculation means 213 for selecting, from among the plurality of first areas, the first areas the detection amount of which differs from the reference detection amount by a value smaller than a prescribed threshold, as second areas 4, 5, 7, 8, 9, while including the reference area, and for calculating a detection amount of the focus detection area using detection amounts of the plurality of second areas.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a focus detection technique for performing focus detection for autofocus (phase difference AF) by a phase difference detection method in an optical apparatus such as a digital camera.

  Phase difference AF divides the light incident on the photographing optical system from the subject to form a pair of subject images, and from the phase difference between the pair of image signals obtained by photoelectrically converting the pair of subject images by the light receiving sensor. This is an AF method in which a defocus amount is obtained and focus control is performed using the defocus amount. In addition, as such phase difference AF, there is so-called imaging plane phase difference AF in which an imaging element that performs imaging for acquiring a captured image is used as a light receiving sensor. In the imaging surface phase difference AF, a pair of subject images are formed by a plurality of pixels each having a microlens provided in the imaging device, and these are photoelectrically converted to obtain a pair of image signals.

  In these phase difference AFs, as shown in FIGS. 13A and 13B, when a plurality of subjects having different distances are included in the AF area in the imaging screen, that is, when subject perspective conflicts occur, AF may be completed without focusing on either the near subject or the far subject. In Patent Document 1, when it is determined that there is a subject's perspective conflict by detecting the phase difference in the AF area, a plurality of small AF areas are newly added so as to include the AF area, and each small AF area is positioned again. A method for avoiding incomplete AF due to perspective conflict by performing phase difference detection is disclosed.

Japanese Patent Application Laid-Open No. 08-015603

  However, AF is completed when a new small AF area is set again and the phase difference is detected again every time a distance conflict is determined from the phase difference detection result as in the method disclosed in Patent Document 1. It takes longer time to complete. Further, even if a small AF area is newly established and a phase difference is detected again, it is not always possible to avoid distance conflict depending on the position and size of the small AF area. Furthermore, there is a possibility that the phase difference AF cannot be tracked with respect to a moving subject by setting a small AF area smaller than the original AF area.

  The present invention provides a focus detection apparatus capable of performing focus detection by a high-speed and good phase difference detection method even if subject collision occurs, and an optical apparatus equipped with the focus detection apparatus.

  A focus detection apparatus according to an aspect of the present invention includes a phase difference between a pair of image signals obtained from a focus detection region of an image sensor that captures a subject image formed by a shooting optical system, and a shooting optical system based on the phase difference. The detected amount which is one of the defocus amounts is calculated. The focus detection apparatus includes a plurality of first areas in a focus detection area, a first calculation unit that calculates a detection amount for each first area, and a reference area selected from the plurality of first areas A reference setting unit that sets the detection amount of the reference region as a reference detection amount, and a first region in which a difference from the reference detection amount is smaller than a predetermined threshold among the plurality of first regions as a second region And a second calculation means for calculating the detection amount of the focus detection region using the detection amounts of the plurality of second regions.

  Note that an optical apparatus including the focus detection device and a control unit that performs focus control using the detection amount obtained by the focus detection device also constitutes another aspect of the present invention.

  In addition, a focus detection program according to another aspect of the present invention includes a phase difference between a pair of image signals obtained from a focus detection region of an imaging element that captures a subject image formed by a photographing optical system, and the phase difference. It is a computer program for causing a computer to execute a focus detection process for calculating a detection amount which is one of the defocus amounts of a photographing optical system based thereon. The focus detection process includes providing a plurality of first areas in the focus detection area, calculating a detection amount for each first area, selecting a reference area from the plurality of first areas, A process of setting the detection amount of the reference area as the reference detection amount, and a plurality of first areas including a reference area including a reference area, the first area having a difference from the reference detection amount smaller than a predetermined threshold is selected. And processing for calculating the detection amount of the focus detection region using the detection amounts of the plurality of second regions.

  According to the present invention, in the phase difference detection method, high-speed and good focus detection can be performed even when subject perspective conflict occurs.

1 is a block diagram illustrating a configuration of a lens interchangeable camera system that is Embodiment 1 of the present invention. FIG. The figure which shows the pixel arrangement | sequence which is not corresponding to imaging surface phase difference AF, and the pixel arrangement | sequence corresponding to imaging surface phase difference AF. 7 is a flowchart showing an imaging process in Embodiment 1 (and Embodiment 2 of the present invention). 10 is a flowchart illustrating still image capturing processing in the first embodiment (and the second embodiment). 3 is a flowchart illustrating focus detection processing according to the first embodiment. 5 is a flowchart showing a used image shift amount setting process in Embodiment 1. FIG. 3 is a diagram illustrating an AF area used in focus detection processing according to the first embodiment. The figure which shows the image signal obtained from AF area | region shown in FIG. The figure which shows the relationship between the shift amount and correlation amount of the image signal shown in FIG. The figure which shows the relationship between the shift amount of the image signal shown in FIG. 8, and a correlation change amount. 6 is a flowchart illustrating processing for setting an image shift amount difference threshold according to the first exemplary embodiment. 7 is a flowchart showing AF processing in Embodiment 1 (and Embodiment 2). The figure which shows the example of a near-far conflict state and the false focusing which generate | occur | produces in the state. FIG. 3 is a diagram illustrating a relationship between an AF area and a scanning line in Embodiment 1. FIG. 4 is a diagram illustrating a method for selecting a reference scan line from scan lines in an AF area according to the first embodiment. FIG. 6 is a diagram illustrating an example of avoiding perspective conflict in an AF area according to the first embodiment. The figure which shows the pixel structural example different from FIG. 2 in an imaging surface phase difference detection system. 10 is a flowchart illustrating focus detection processing according to the second embodiment. 10 is a flowchart illustrating a used defocus amount setting process according to the second embodiment. 9 is a flowchart illustrating a defocus amount difference threshold setting process according to the second embodiment.

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

  FIG. 1 shows the configuration of a lens-interchangeable image pickup apparatus (hereinafter simply referred to as a camera) 20 as an optical apparatus that is Embodiment 1 of the present invention. The interchangeable lens 10 is detachably attached to the camera 20. The camera 20 and the interchangeable lens 10 constitute a camera system.

  First, the configuration of the interchangeable lens 10 will be described. The interchangeable lens 10 houses a photographic optical system including a fixed lens 101, a diaphragm 102, and a focus lens 103. The diaphragm 102 is driven by a diaphragm driving unit 104 controlled by the lens control unit 106, and controls the amount of light incident on the image sensor 201 described later. The focus lens 103 is driven by a focus lens driving unit 105 controlled by the lens control unit 106, and moves the focus lens 103 in the optical axis direction of the photographing optical system.

  The lens operation unit 107 allows the user to perform various settings related to the interchangeable lens 10 such as switching between AF (autofocus) mode and MF (manual focus) mode, setting of a shooting distance range, and on / off setting of image stabilization (image blur correction). An operation member such as a switch for performing the operation is included. When the lens operation unit 107 is operated, an operation signal corresponding to the operation is input to the lens control unit 106, and the lens control unit 106 performs control according to the operation signal.

  The lens control unit 106 is configured by a microcomputer, and controls the aperture driving unit 104 and the focus lens driving unit 105 in accordance with a control command received from a camera control unit 212 (to be described later). It transmits to the control part 212.

  Next, the configuration of the camera 20 will be described. The image sensor 201 is constituted by a CCD sensor or a CMOS sensor. Light incident on the camera 20 from the subject through the photographing optical system forms a subject image on the light receiving surface of the image sensor 201. The image sensor 201 photoelectrically converts (images) a subject image by a photodiode provided in each of a plurality of pixels arranged on the light receiving surface, and accumulates electric charges. The electric charge accumulated in each photodiode is read as a voltage signal for each timing signal output from the timing generator 215 in accordance with an instruction from the camera control unit 212.

  Each pixel of the image sensor 201 used in this embodiment is composed of two (a pair) of photodiodes A and B and one microlens provided for the pair of photodiodes A and B. . Each pixel divides incident light by a microlens to form a pair of optical images on the pair of photodiodes A and B, and the pair of photodiodes A and B uses a pair of AF signals to be described later. Pixel signals (A signal and B signal) are output. Further, by adding the outputs of the pair of photodiodes A and B, an imaging signal (A + B signal) can be obtained.

  By combining a plurality of A signals and a plurality of B signals output from a plurality of pixels, respectively, an AF signal (in other words, an imaging surface phase difference AF) used for AF (hereinafter referred to as imaging surface phase difference AF) is used. A pair of image signals as a focus detection signal) is obtained. An AF signal processing unit 204 described later performs a correlation operation on the pair of image signals, calculates a phase difference (hereinafter referred to as an image shift amount) that is a shift amount of the pair of image signals, and further calculates the image shift amount. From this, the defocus amount (and defocus direction) of the photographing optical system is calculated.

  2A shows a pixel configuration not corresponding to the imaging plane phase difference AF, and FIG. 2B shows a pixel configuration corresponding to the imaging plane phase difference AF. In any of the figures, a Bayer array is used, where R indicates a red color filter, B indicates a blue color filter, and Gr and Gb indicate green color filters. The pixel configuration shown in FIG. 2B corresponding to the imaging plane phase difference AF corresponds to one pixel (enclosed by a solid line) in the pixel configuration not corresponding to the imaging plane phase AF shown in FIG. In the pixel, two photodiodes A and B divided into two in the horizontal direction in the figure are provided. Note that the pixel dividing method illustrated in FIG. 2B is merely an example, and the pixel may be divided in the vertical direction in the drawing, or may be divided into two in the horizontal and vertical directions (total of 4 divisions). In addition, a plurality of types of pixels that are divided by different division methods in the same image sensor may be included.

  The CDS / AGC / AD converter 202 performs correlated double sampling, gain adjustment, and AD conversion for removing reset noise on the AF signal and the imaging signal read from the imaging element 201. The converter 202 outputs the imaging signal and the AF signal that have undergone these processes to the image input controller 203 and the AF signal processing unit 204, respectively.

  The image input controller 203 stores the imaging signal output from the converter 202 as an image signal in the SDRAM 209 via the bus 21. The image signal stored in the SDRAM 209 is read by the display control unit 205 via the bus 21 and displayed on the display unit 206. In the recording mode in which the image signal is recorded, the image signal stored in the SDRAM 209 is recorded on the recording medium 208 such as a semiconductor memory by the recording medium control unit 207.

  The ROM 210 stores a control program and a processing program executed by the camera control unit 212 and various data necessary for the execution. The flash ROM 211 stores various setting information relating to the operation of the camera 20 set by the user.

  An AF signal processing unit 204 as a focus detection device performs a correlation operation on a pair of image signals which are AF signals output from the converter 202, and calculates an image shift amount and reliability of the pair of image signals. . The reliability is calculated using two-image coincidence described later and the steepness of the correlation change amount. The AF signal processing unit 204 sets the position and size of an AF area (focus detection area) that is an area for performing focus detection and AF within the imaging screen. The AF signal processing unit 204 outputs information on the image shift amount (detection amount) and reliability calculated in the AF area to the camera control unit 212.

  The AF signal processing unit 204 includes a perspective conflict determination unit 213. The perspective conflict determination unit 213 determines whether or not there is a perspective conflict in which a plurality of subjects having different distances exist in the AF area set by the AF signal processing unit 204, and an image is determined according to the determination result. Change the calculation method of the deviation amount. As a result, it is possible to perform imaging surface phase difference AF that suppresses the influence of perspective conflict.

  The camera control unit 212 performs an AF signal processing unit as necessary based on the information indicating the image shift amount, the reliability, and the state of the interchangeable lens 10 and the camera 20 obtained by the AF signal processing unit 204 and the perspective conflict determination unit 213. 204 or the setting of the perspective conflict determination unit 213 is changed. For example, when the image shift amount is greater than or equal to a predetermined amount with respect to the AF signal processing unit 204, the correlation calculation region is set wide, or the type of the bandpass filter is changed according to the contrast of the pair of image signals. Or Further, the threshold used for the perspective conflict determination is changed for the perspective conflict determination unit 213 according to the position of the AF area set in the camera 20 and the information of the aperture 102 of the interchangeable lens 10. Details of the correlation calculation will be described later.

  In this embodiment, a total of three signals, that is, a pair of image signals that are imaging signals and AF signals, are acquired from the imaging element 201. However, considering the load on the image sensor 201, for example, a total of two signals, that is, an imaging signal and one AF image signal are extracted, and the difference between the extracted imaging signal and the AF image signal is calculated as another AF image. It may be used as a signal.

  The camera control unit 212 controls these while exchanging information with each unit in the camera 20. In addition, the camera control unit 212 performs user operations such as power ON / OFF, change of various settings, imaging processing, AF processing, and recorded image reproduction processing in response to input from the camera operation unit 214 based on user operations. Various corresponding processes are executed. Furthermore, the camera control unit 212 transmits a control command for the interchangeable lens 10 (lens control unit 106) and information about the camera 20 to the lens control unit 106, and acquires information about the interchangeable lens 10 from the lens control unit 106. . The camera control unit 212 is configured by a microcomputer, and controls the entire camera system including the interchangeable lens 10 by executing a computer program stored in the ROM 210.

  The camera control unit 212 calculates a defocus amount using the image shift amount in the AF area calculated by the AF signal processing unit 204, and drives the focus lens 103 through the lens control unit 106 based on the defocus amount. To control. The specific AF area here is an area arranged with the position set by the user through the camera operation unit 214 as the center.

  In this embodiment, the user sets (places) the AF area through the camera operation unit 214, but the camera 20 has a function of detecting a specific subject (for example, a human face) from the imaging screen. The AF area may be set based on the detection result.

  The subject perspective conflict will be described with reference to FIGS. In phase difference AF, if there is a perspective conflict with the subject being captured, it is in focus even though neither the near subject nor the far subject is in focus. There is a case where AF is completed by erroneously determining that there is. This is because when performing a correlation calculation, the correlation amount corresponding to the distance (intermediate distance) between them is the largest, not the correlation amount corresponding to either the near-side or far-side subject distance. is there. Furthermore, when the focus lens is located at a position corresponding to the intermediate distance, there is a subject with different defocus directions on the near side and the far side from the intermediate distance, so that the correlation amount is balanced and the defocus amount is This is because it becomes smaller and erroneously determined to be in focus.

  In order to solve this problem, in this embodiment, even when there are a plurality of subjects having different distances in the AF area, the image shift amount calculated from each image line in the AF area of the image sensor 201 is selected. Only the image shift amount for a subject at a specific distance is used. Specifically, the perspective conflict determination unit 213 selects one subject that can be determined as the main subject in the AF area where the perspective conflict has occurred, and uses only the image shift amount with respect to the selected subject to determine the defocus amount. Is calculated and AF is performed. As a result, it is possible to obtain a focused state for a main subject that has been erroneously determined as a focused state and has been blurred. The processing performed by the perspective conflict determination unit 213 (hereinafter referred to as perspective conflict avoidance processing) will be described later.

  Hereinafter, processing performed by the camera 20 will be described. The camera control unit 212 performs the following processing according to an imaging processing program that is a computer program.

  The flowchart of FIG. 3 shows the procedure of the imaging process. S means a step.

  In step S301, the camera control unit 212 performs initialization processing for various settings.

  In S302, the camera control unit 212 determines whether the imaging mode of the camera 20 is the moving image imaging mode or the still image imaging mode. The camera control unit 212 proceeds to S303 when in the moving image capturing mode and proceeds to S304 when in the still image capturing mode.

  In S303, the camera control unit 212 performs a moving image capturing process, and the process proceeds to S305. In S304, the camera control unit 212 performs a still image capturing process, and proceeds to S305. Although the perspective conflict avoidance process can be performed in either the moving image capturing mode or the still image capturing mode, a case will be described in the present embodiment where the perspective conflict avoiding process is performed in the still image capturing mode. In this embodiment, the description of the moving image imaging process is omitted.

  In step S305, the camera control unit 212 determines whether the imaging process has been stopped. When the imaging process is stopped, operations other than the imaging process are performed, such as when the power of the camera 20 is turned off through the camera operation unit 214, a setting process by a user, and a reproduction process for confirming a captured image. It is time when If the imaging process has not been stopped, the process proceeds to S306. If the imaging process has been stopped, the imaging process is terminated.

  In S306, the camera control unit 212 determines whether or not the imaging mode has been changed. If changed, the camera control unit 212 returns to S301 and performs the imaging process in the changed imaging mode after performing the initialization process. On the other hand, if the imaging mode has not been changed, the camera control unit 212 returns to S302 and continues processing in the current imaging mode.

  Next, the still image capturing process performed in S304 in FIG. 3 will be described using the flowchart in FIG.

  In S401, the camera control unit 212 causes the AF signal processing unit 204 (including the perspective conflict determination unit 213) to perform focus detection processing. The focus detection process is a process of acquiring information on the defocus amount and reliability for performing the imaging plane phase difference AF, and details thereof will be described later.

  In step S <b> 402, the camera control unit 212 determines whether an AF process start instruction (hereinafter referred to as an AF instruction) is input (turned on) from the camera operation unit 214. The AF instruction is output from the camera operation unit 214 when a shutter button provided on the camera 20 is pressed halfway, or when an AFON button for executing AF is pressed. If the AF instruction is input, the camera control unit 212 proceeds to S403, and if the AF instruction is not input, the camera control unit 212 proceeds to S404.

  In S403, the camera control unit 212 performs AF processing. This AF processing will be described later.

  In step S <b> 404, the camera control unit 212 determines whether an imaging processing start instruction (hereinafter referred to as an imaging instruction) is input (turned on) from the camera operation unit 214. The imaging instruction is output from the camera operation unit 214 when the shutter button is pressed fully. The camera control unit 212 proceeds to S405 when an imaging instruction is input, and proceeds to S407 when an imaging instruction is not input.

  In S405, the camera control unit 212 determines whether or not the focus is currently stopped by the AF process in S403. The in-focus stop state is a state in which the focus lens 103 is stopped when the photographing optical system is in a focus state. If it is not in the focus stop state, the camera control unit 212 proceeds to S403, and obtains the focus state by starting or continuing the AF process. If the in-focus state is in effect, the camera control unit 212 proceeds to S406, performs an imaging process, stores the captured image (recorded image) in the recording medium 208 via the recording medium control unit 207, and proceeds to S407.

  In step S407, the camera control unit 212 releases the focus stop state and ends the still image capturing process.

  Next, the focus detection process performed by the AF signal processing unit 204 in S401 of FIG. 4 will be described using the flowchart of FIG. The AF signal processing unit 204 is configured by a microcomputer, and performs focus detection processing according to a focus detection program (which may be a part of an imaging processing program) as a computer program.

  First, in S501, the AF signal processing unit 204 sets an AF area (focus detection area) to be an AF target on the imaging screen (that is, the imaging element 201). As described above, the AF area is set based on an instruction from the user through the camera operation unit 214 or based on a detection result of a specific subject.

  In step S <b> 502, the AF signal processing unit 204 acquires a pair of image signals as AF signals from a plurality of pixels included in the AF area of the image sensor 201.

  In step S503, the AF signal processing unit 204 calculates a correlation amount between the pair of image signals while relatively shifting the acquired pair of image signals by one pixel (1 bit). The calculation of the correlation amount is performed as described later in each of a plurality of pixel lines (first area: hereinafter referred to as scanning lines) provided in the AF area (in the focus detection area). The subsequent processing from S504 to S507 is similarly performed for each scanning line.

  FIG. 14 shows an example of scanning lines in the AF area. In this example, nine scanning lines 1 to 9 extending in the horizontal direction are provided in the rectangular AF area so as to be adjacent to each other in the vertical direction. The number of scanning lines and the extending direction are not limited to this.

  In step S504, the AF signal processing unit 204 obtains a correlation change amount from the correlation amount for each scanning line calculated in step S503. A method of calculating the correlation change amount will be described later.

  In step S505, the AF signal processing unit 204 calculates an image shift amount for each scanning line using the correlation change amount calculated in step S504. A method for calculating the image shift amount will be described later.

  Further, in S506, the AF signal processing unit 204 calculates a reliability indicating the reliability of the image shift amount calculated in S505 for each scanning line. A method for calculating the reliability will be described later. The AF signal processing unit 204 corresponds to first calculation means and reliability calculation means.

  In step S507, the perspective conflict determination unit 213 determines which scan line image in the AF area based on the image shift amount for each scan line calculated in step S505 and the reliability for each scan line calculated in step S506. It is determined whether the shift amount is used for calculating the defocus amount. The used image shift amount setting process, which is a process here, is a process for setting the image shift amount used for calculating the image shift amount in the AF area in which the influence of perspective conflict is suppressed, and details thereof will be described later. The perspective conflict determination unit 213 corresponds to a reference setting unit and a second calculation unit.

  In step S508, the AF signal processing unit 204 calculates the defocus amount of the AF area using the image shift amount of the AF area finally calculated in step S507, and ends the focus detection process.

  Next, the focus detection process will be described in detail. FIG. 7 shows an example of the AF area 702 on the pixel array 701 of the image sensor 201 in the focus detection process. Shift areas 703 on both sides of the AF area 702 are areas necessary for correlation calculation. Therefore, a region 704 obtained by combining the AF region 702 and the shift region 703 is a pixel region necessary for the correlation calculation. In the figure, p, q, s, and t represent the coordinates in the horizontal direction (x-axis direction), p and q represent the x-coordinates of the start and end points of the pixel area 704, and s and t represent the AF areas, respectively. The x coordinate of the start point and end point of 702 is shown.

  FIG. 8 shows an example of a pair of image signals for AF acquired from a plurality of pixels included in the AF area 702 shown in FIG. A solid line 801 is one image signal A, and a broken line 802 is the other image signal B. 8A shows the image signals A and B before the shift, and FIGS. 8B and 8C respectively shift the image signals A and B in the plus direction and the minus direction from the state of FIG. 8A. Shows the state. When calculating the correlation amount between the pair of image signals A801 and B802, both the image signals A801 and B802 are shifted by one bit in the direction of the arrow.

  Next, a method for calculating the correlation amount will be described. First, as shown in FIGS. 8B and 8C, the image signals A801 and B802 are shifted by 1 bit, respectively, and the sum of the absolute values of the differences between the image signals A801 and B802 is calculated. When the shift amount is i, the minimum shift amount is p-s, the maximum shift amount is qt, x is the start coordinate of the AF area 702, and y is the end coordinate of the AF area 702, the correlation amount COR is It can be calculated by the following equation (1).

FIG. 9A shows an example of the relationship between the shift amount and the correlation amount COR. The horizontal axis indicates the shift amount, and the vertical axis indicates the correlation amount COR. Among the extreme values 902 and 903 in the correlation amount 901 that changes with the shift amount, the degree of coincidence between the pair of image signals A and B becomes the highest in the shift amount corresponding to the smaller correlation amount.

  Next, a method for calculating the correlation change amount will be described. The difference in the correlation amount at every other shift in the waveform of the correlation amount 901 shown in FIG. 9A is calculated as the correlation change amount. When the shift amount is i, the minimum shift amount is ps, and the maximum shift amount is qt, the correlation change amount ΔCOR can be calculated by the following equation (2).

FIG. 10A shows an example of the relationship between the shift amount and the correlation change amount ΔCOR. The horizontal axis indicates the shift amount, and the vertical axis indicates the correlation change amount ΔCOR. The correlation change amount 1001 that changes with the shift amount changes from plus to minus at the portions 1002 and 1003. A state in which the correlation change amount is 0 is called zero crossing, and the degree of coincidence between the pair of image signals A and B is the highest. Therefore, the shift amount giving the zero cross becomes the image shift amount.

  FIG. 10B is an enlarged view of a portion indicated by 1002 in FIG. Reference numeral 1004 denotes a part of the correlation change amount 1001. A method for calculating the image shift amount PRD will be described with reference to FIG.

  The shift amount (k−1 + α) giving the zero cross is divided into an integer part β (= k−1) and a decimal part α. The decimal part α can be calculated by the following equation (3) from the similar relationship between the triangle ABC and the triangle ADE in the figure.

The integer part β can be calculated from the following equation (4) from FIG.

β = k−1 (4)
Then, the image shift amount PRD can be calculated from the sum of α and β.

  As shown in FIG. 10 (a), when there are a plurality of zero crossings of the correlation change amount ΔCOR, the one having the larger steepness of the change in the correlation change amount ΔCOR in the vicinity thereof is set as the first zero cross. This steepness is an index indicating the ease of AF, and the larger the value, the easier the AF is performed. The steepness maxder can be calculated by the following equation (5).

Thus, in this embodiment, when there are a plurality of correlation change amount zero crosses, the first zero cross is determined by the steepness, and the shift amount giving the first zero cross is defined as the image shift amount.

  Next, a method for calculating the reliability of the image shift amount will be described. The reliability of the image shift amount can be defined by the matching degree (hereinafter, referred to as two-image matching degree) fnclvl of the pair of image signals A and B and the steepness of the correlation change amount described above. The degree of coincidence of two images is an index representing the accuracy of the image shift amount. In the correlation calculation method in this embodiment, the smaller the value, the better the accuracy.

  FIG. 9B is an enlarged view of the portion indicated by 902 in FIG. 9A, and 904 is a part of the correlation amount 901. As can be seen from FIG. 9B, the two-image coincidence degree fnclvl can be calculated by the following equation (6).

  Next, the use image shift amount setting process performed by the perspective conflict determination unit 213 in S507 of FIG. 5 will be described using the flowchart of FIG.

  In step S601, the perspective conflict determination unit 213 determines whether or not there is a scan line having a reliability higher than a predetermined value in the AF area. The perspective conflict determination unit 213 proceeds to S602 when there is no such scan line, and proceeds to S603 when there is such a scan line. As the predetermined value for the reliability here, it is desirable to set a value that can be considered reliable if the defocus amount calculated from the image shift amount is higher than that, or only in the defocus direction.

  In step S <b> 602, the perspective conflict determination unit 213 determines a value obtained by averaging all the image shift amounts calculated from each of the plurality of scanning lines in the AF area as the “used image shift amount”, and ends this processing. If there is no highly reliable scanning line in the AF area, that is, if the defocus amount and the defocus direction are not reliable, AF cannot be performed using the defocus amount in the first place. For this reason, since there is a high possibility that the image shift amount determined in this AF area does not make much sense, in this embodiment, all scan lines are used without selecting scan lines for avoiding perspective conflict.

  On the other hand, in step S <b> 603, the perspective conflict determination unit 213 selects a scan line that is located at the center of the AF area or at a position closer to the center and has a higher reliability than the predetermined value (first reliability) as a reference scan line (reference area). ) To select.

  In step S604, the perspective conflict determination unit 213 determines whether there are a plurality of reference scanning lines selected in step S603. That is, in S603, it is determined whether or not a plurality of reference scanning lines having a reliability higher than a predetermined value and the same distance from the center in the AF area are selected. For example, when there are a plurality of selected reference scan lines as shown in FIGS. 15A and 15B, the perspective conflict determination unit 213 proceeds to S605 and selects the selected reference scan line as shown in FIG. 15C. If there is one, the process proceeds to S606.

  In step S <b> 605, the perspective conflict determination unit 213 sets the average value of the image shift amounts obtained from the selected reference scanning line as the variable X. Then, the process proceeds to S607. On the other hand, in S <b> 606, the perspective conflict determination unit 213 sets the image displacement amount obtained by the selected reference scanning line as the variable X. In S605 and S606, as a variable X, a reference image shift amount (reference detection amount), which is a reference image shift amount for performing perspective conflict determination (or perspective conflict processing), is set. That is, if there is one reference scan line, the image shift amount obtained with the reference scan line is set as the reference image shift amount (X), and if there are a plurality of reference scan lines, the image is obtained with those reference scan lines. An average value of image shift amounts is set as a reference image shift amount (X).

  In this embodiment, on the assumption that the main subject that the user wants to focus on is likely to exist near the center of the AF area, it is within the center of the AF area or within a predetermined center vicinity (for example, within one scanning line from the center). Are preferentially selected as reference scanning lines in S603.

  After setting the reference image shift amount for performing the perspective conflict determination in this manner, the perspective conflict determination unit 213 performs the perspective conflict determination from S607 to S617, and “use image shift amount” considering the perspective conflict in the AF area. Is calculated.

  First, in S607, the perspective conflict determination unit 213 sets initial values of 0, 1, and 0 to the variables P, M, and N, respectively, and proceeds to S608. The variable P is an image shift amount holding variable, and the variable M is a variable indicating the number of the scanning line in the AF area. The variable N is a variable for holding the number of scanning lines used for calculating the used image shift amount in the AF area.

  In step S <b> 608, the perspective conflict determination unit 213 sets an image shift amount difference threshold (predetermined threshold). A perspective conflict determination unit 213 calculates a difference between a reference image shift amount and an image shift amount obtained from each scanning line in a perspective conflict determination process described later, and sets an image shift amount difference threshold value to determine the magnitude of the difference. Set. The image shift amount difference threshold is set according to the parameters of the camera 20 and the parameters of the interchangeable lens 10. Details of the image deviation amount difference threshold setting process will be described later.

  In step S609, the perspective conflict determination unit 213 determines whether the variable M is equal to or less than the number of scanning lines in the AF area to be processed later. If the variable M is equal to or less than the number of scanning lines. Proceeds to S610, otherwise proceeds to S615. Here, the variable M is counted up in a loop process to be described later, and when the variable M exceeds the number of scanning lines in the AF area, the process for all the scanning lines is completed, and the process proceeds to S615.

  In step S610, the perspective conflict determination unit 213 calculates the difference between the image shift amount obtained from the Mth scanning line in the AF area and the reference image shift amount X, and the difference is the image shift amount difference set in step S608. It is determined whether or not it is below the threshold value (smaller). The perspective conflict determination unit 213 proceeds to S611 if the difference is equal to or less than the image shift amount difference threshold value, and proceeds to S614 if it is not equal to or less than the threshold value.

  In S611, the perspective conflict determination unit 213 determines whether or not the reliability of the Mth scanning line is higher than a predetermined value (second reliability). The predetermined value here is also the same as the predetermined value used in S601 and S603. However, the second predetermined value may be different from the first predetermined value used in S601 and S603.

  The perspective conflict determination unit 213 determines whether or not there is an effect of perspective conflict on the Mth scan line by the processing of S610 and S611 described above. That is, in S610, it is determined whether or not the image shift amount of the Mth scanning line matches or is close to the reference image shift amount X (has only a difference equal to or less than the image shift amount difference threshold). If the image shift amount of the M-th scan line matches or is close to the reference image shift amount X, the M-th scan line captures a subject that is approximately the same distance as the reference scan line that is assumed to capture the main subject. There is a high possibility. On the other hand, if the image shift amount of the Mth scan line is far from the reference image shift amount X, the Mth scan line may capture a subject at a different distance from the main subject captured by the reference scan line. Is expensive. In step S611, the reliability is checked in order to determine whether the image shift amount of the Mth scan line is reliable in the first place. If the reliability is higher than a predetermined value, that is, if the defocus amount or defocus direction calculated from this image shift amount is reliable, the image shift amount of the Mth scanning line that matches or is close to the reference image shift amount is used in S610. AF can be performed.

  As described above, when the perspective conflict determination unit 213 determines in S610 and S611 that the image shift amount of the M-th scanning line is not affected by the perspective conflict and can be used for AF, the distance conflict determination unit 213 determines in S612. Proceed to Hereinafter, the scanning line in which it is determined that the image shift amount can be used for AF is referred to as a used scanning line (second region). On the other hand, if it is determined that the image shift amount of the Mth scanning line is affected by perspective conflict and cannot be used for AF, the process proceeds to S614.

  In step S <b> 612, the perspective conflict determination unit 213 substitutes a value obtained by adding the variable P and the image shift amount of the Mth scanning line (used scanning line) to the variable P. A variable P represents the sum of image shift amounts of the used scanning lines.

  Next, in S613, the perspective conflict determination unit 213 substitutes a value obtained by adding 1 to the variable N to the variable N. In order to perform normalization in the process described later while holding the image shift amount that is not affected by the perspective conflict in S612, the number of the used scan line that is not affected by the perspective conflict is set to the variable M in S614. To keep.

  In step S614, the perspective conflict determination unit 213 counts up the number M of scanning lines in the AF area. Then, the process returns to S609. In this way, the processing from S610 to S614 is repeated until the variable M reaches the number of scanning lines in the AF area in S609, and whether or not the image shift amount is affected by the perspective conflict for all the scanning lines. A loop process is performed to make the determination. As a result, a plurality of use scan lines including the reference scan line are selected, or only one of the reference scan lines is selected.

  When the process proceeds from S609 to S615, the perspective conflict determination unit 213 performs normalization by dividing the sum P of image shift amounts of the used scanning lines held in S612 by the number N of used scanning lines in S613. The image shift amount thus set is set as the use image shift amount, and this processing is terminated.

  FIG. 16 shows an example of avoiding perspective conflicts in the AF area using the used shift amount set in the used image shift amount setting process. FIG. 16 shows an AF in which the subject 1 (the main subject from which the focus state is desired to be obtained) and the subject 2 on the far side are set in the imaging screen from the position where the current focus lens 103 is in focus. The state included in the area is shown. In the example of FIG. 16, nine scan lines 1 to 9 exist in the AF area, and the reliability and the image shift amount described in the figure are obtained for each of these scan lines. . Note that the reliability in FIG. 16 is “OK” means that the defocus amount calculated using the image shift amount is determined to be reliable, and “NG” means not. . Regarding the image shift amount, + indicates the image shift amount toward the close side, and-indicates the image shift amount toward the infinity side. Further, the image shift amount difference threshold is set to ± 0.3 pixels.

  In FIG. 16, scanning lines 1 and 2 capture not the subject 1 but the subject 2. The scanning line 3 captures both the subject 1 and the subject 2. In this situation, when the average value obtained by adding all the image shift amounts of the scanning lines 1 to 9 is used as the used image shift amount, the scan line 1 to 3 that captures the subject 2 has an excellent effect on the subject 1. The in-focus state cannot be obtained, and the subject 1 is blurred.

  On the other hand, in the used image shift amount setting process described above, the perspective conflict determination unit 213 first selects the scan line 5 positioned at the center of the AF area and having a reliability of OK as the reference scan line (S603). . Then, the image shift amount of the reference scanning line 5 + 3 pixels is set as the reference image shift amount (S606).

  Next, the perspective conflict determination unit 213 compares the reference image shift amount (X) with the image shift amounts of all the scanning lines 1 to 9. Then, the scanning lines 4, 5, 7, and 8 having an image shift amount of +2.7 pixels to +3.3 pixels, in which the difference of the reference image shift amount from +3 pixels is equal to or less than the image shift amount difference threshold ± 0.3 pixel. , 9 are selected as candidates for use scanning lines (S610).

  Further, the near / far conflict determination unit 213 selects only the scan lines 4, 5, 7, 8, and 9 having reliability OK among the scan lines that are candidates for the use scan line (S611). These use scanning lines 4, 5, 7, 8, and 9 capture the subject 1, and the reliability of the image shift amount is high (OK). Therefore, by calculating the defocus amount using the image shift amount calculated by adding and averaging these image shift amounts as the used image shift amount, the subject 2 is included even if the subject 2 is included in the AF area. It is possible to obtain a focused state with respect to the subject 1 without being affected by the above.

  Note that the number of scan lines and the image shift amount difference threshold in the AF area shown in FIG. 16 are merely examples, and other scan line numbers and image shift amount difference thresholds may be used.

  Next, an image shift amount difference threshold setting process performed by the perspective conflict determination unit 213 in S608 of FIG. 6 will be described using the flowchart of FIG.

  In S1101, the perspective conflict determination unit 213 determines whether or not the image height (position) of the AF area set in S501 in FIG. 5 is lower than a predetermined image height, and the image height is lower than the predetermined image height. If there is, the process proceeds to S1102, and if not (higher than the predetermined image height), the process proceeds to S1105.

  In S1102, the perspective competition determination unit 213 determines whether or not the gain (sensor gain) applied to the output of the image sensor 201 is smaller than the predetermined gain. If smaller than the predetermined gain, the process proceeds to S1103, otherwise (predetermined gain). If greater than, the process proceeds to S1105.

  In S1103, the perspective conflict determination unit 213 determines whether or not the contrast amount of the reference scanning line selected in S603 of FIG. 6 is higher than a predetermined contrast amount. If it is higher than the predetermined contrast amount, the process proceeds to S1104. If not (lower than the predetermined contrast amount), the process proceeds to S1105. As the contrast amount, for example, the smaller difference of the differences between the maximum signal value and the minimum signal value of the pair of image signals A and B for which the correlation calculation is performed is used. If there are a plurality of reference scan lines in S603, the smallest difference among the plurality of reference scan lines is used. The use of a smaller amount of contrast assumes the worst case. However, this is an example, and the contrast amount may be obtained by another definition and method.

  In step S1104, the perspective conflict determination unit 213 sets the image shift amount difference threshold value to α and ends the present process. On the other hand, in S1105, the perspective conflict determination unit 213 sets the image shift amount difference threshold value to β, and ends the present process. The image deviation amount difference threshold values α and β are set so that α <β. The reason why the smaller image shift amount threshold value α is set in S1104 is to assume a case where the image shift amount is detected with high accuracy. When the accuracy of the image shift amount is detected with high accuracy, in order to exclude the image shift amount affected by the perspective conflict in the used image shift amount setting process shown in FIG. Set smaller. On the other hand, in S1105, assuming a case where the accuracy of the image shift amount is not good, a larger image shift amount difference threshold β is set in consideration of variations in the image shift amount.

  In this embodiment, three cases are assumed as the case where the accuracy of the image shift amount deteriorates. First, in S1101, the image height of the AF area is determined. This is because, in the pixel configuration corresponding to the imaging surface phase difference AF shown in FIG. 2B, the difference in the amount of light incident on the photodiodes A and B tends to increase as the image height increases. This is because there is a high possibility that the degree of coincidence between the signals A and B is lowered and the accuracy of the image shift amount is lowered.

  In S1102, the magnitude of the sensor gain is determined. This is because the noise component of the pair of image signals A and B increases as the sensor gain increases, and the possibility that the accuracy of the image shift amount decreases.

  Further, in S1103, the magnitude of the contrast amount obtained from the image signal A or B is determined. This is because the possibility that the accuracy of the image shift amount decreases as the contrast amount decreases.

  As described above, in the present embodiment, when it can be assumed that the accuracy of the image shift amount is high, the image shift amount difference threshold is set to be small, and the perspective conflict determination is performed more strictly, and when the accuracy of the image shift amount can be assumed to be low. The image deviation amount difference threshold value is set to a large value in consideration of variations in the image deviation amount.

  Next, the AF process performed by the camera control unit 212 in S403 of FIG. 4 will be described using the flowchart of FIG.

  In step S1201, the camera control unit 212 determines whether the AF is currently completed and is in a focus stop state. If the focus stop state is not set, the process proceeds to step S1202, and if the focus stop state is set, the process proceeds to step S1209.

  In S1202, the camera control unit 212 determines whether the reliability of the defocus amount calculated in the focus detection process (S508) in S401 is higher than a predetermined reliability. The reliability here is obtained from the above-mentioned two-image coincidence and the steepness of the image shift amount, and the maximum value of the reliability range in which not only the calculated defocus amount but also the defocus direction is unreliable is predetermined. It is desirable to set it as reliability. The reliability may be obtained by using both the two-image coincidence and the steepness of the image shift amount, or may be obtained by using only one of them. Other indicators such as the signal levels of the two images may be used. If the defocus amount is higher than the predetermined reliability, the process proceeds to S1203. Otherwise, the process proceeds to S1207.

  In step S1203, since the camera control unit 212 performs AF using a defocus amount with high reliability, the camera control unit 212 first determines whether the defocus amount is within the focal depth. If the defocus amount is within the focal depth, the process proceeds to S1204. If it is not within the depth of focus, the process proceeds to S1205.

  In step S1204, the camera control unit 212 considers that the defocus amount is in the in-focus state within the focal depth, shifts to the in-focus stop state, and ends the AF process.

  On the other hand, in S1205, the camera control unit 212 considers that the in-focus state has not yet been obtained, performs lens drive setting for driving the focus lens 103 based on the defocus amount, and proceeds to S1206. The lens driving setting is a setting such as a gain applied to the defocus amount in consideration of the driving speed of the focus lens 103 and an error in the defocus amount.

  In step S1206, the camera control unit 212 transmits a control command for the focus lens 103 to the lens control unit 106 based on the defocus amount and the lens drive setting information set in step S1205. That is, focus control is performed. Thereby, the AF process is terminated.

  On the other hand, in S1207, the defocus amount calculated in S508 cannot be used. For this reason, the camera control unit 212 calculates the defocus amount while moving the focus lens 103 toward the movable end in order to detect the position of the focus lens 103 at which a highly reliable defocus amount is obtained. I do. For this reason, the camera control unit 212 first performs lens drive settings for search drive. The lens driving settings for search driving are settings such as the driving speed of the focus lens 103 and the direction in which driving is started.

  Subsequently, in S1208, the camera control unit 212 transmits a control command for the focus lens 103 to the lens control unit 106 based on the lens drive setting for search driving set in S1207. Then, the AF process ends. In the present embodiment, the camera 20 that can perform only the imaging surface phase difference AF using the output signal of the imaging device 201 has been described. However, when contrast AF can be performed using the output signal of the image sensor 201, contrast AF may be performed when it is determined in S1202 that the reliability of the defocus amount is low.

  In step S1209, the camera control unit 212 holds the focus stop state and ends the AF process.

  In this embodiment, on the assumption that the main subject is present in the center of the AF area, it coincides with the image shift amount (reference image shift amount) of the scanning line (reference scan line) assumed to capture the main subject or A scanning line having a close image shift amount (used scanning line) is selected. Then, the defocus amount is calculated using only the image shift amount (used image shift amount) of the selected used scan line. As a result, it is possible to obtain an excellent focus state with respect to the main subject while suppressing the influence of the perspective conflict of the subject in the AF area. That is, when a subject exists on the far side and the near side, neither subject is focused, it is possible to avoid the AF being completed while being blurred, and to obtain a focused state with respect to the main subject.

  Further, in this embodiment, when the perspective conflict is detected, the AF area is reset and the time-consuming process of performing the focus detection process again is not performed, so that the focus state of the main subject can be smoothly set in a short time. Can be obtained.

  In this embodiment, as shown in FIG. 2B, a pixel configuration capable of performing correlation calculation in the horizontal direction is used, and there are subjects having different distances in the vertical direction in the AF area as shown in FIG. The case of detecting the perspective conflict in the case has been described. However, as shown in FIG. 17A, a pixel configuration that can perform correlation calculation in the vertical direction may be used so that a perspective conflict can be detected when there are subjects with different distances in the horizontal direction in the AF area. . In addition, as shown in FIGS. 17B and 17C, a pixel configuration that can perform correlation calculation in both the horizontal and vertical directions may be used so that perspective conflict can be detected in either the vertical or horizontal directions.

  In FIG. 17A, photodiodes A and B that are divided in two in the vertical direction are provided in two diagonal pixels in 2 × 2 pixels in the horizontal and vertical directions. In FIG. 17B, photodiodes A and B divided in two in the vertical direction are provided in one of the two diagonal pixels in the horizontal and vertical 2 × 2 pixels, and 2 in the horizontal direction with the other pixel. Divided photodiodes A and B are provided. In FIG. 17 (c), photodiodes A to D divided into four are provided for each pixel so that each pixel can detect horizontal and vertical competition.

  Next, a second embodiment of the present invention will be described. In Example 1, a scan line having an image shift amount that matches or is close to the image shift amount obtained from the center scan line of the AF area is selected as a use scan line. On the other hand, in the second embodiment, the scanning line to be used is selected based on the defocus amount (detection amount) calculated based on the image shift amount obtained in S505 of FIG.

  The configuration of the interchangeable lens camera system including the interchangeable lens and the camera in this embodiment is the same as that shown in FIG. In addition, the imaging process, the still image imaging process, and the AF process in the present embodiment are the same as those illustrated in FIGS. 3, 4, and 12 in the first embodiment. In the present embodiment, the same reference numerals as those in the first embodiment are given to the constituent elements common to the first embodiment.

  The focus detection process performed by the AF signal processing unit 204 in S401 of FIG. 4 will be described using the flowchart of FIG. The processing from S1801 to S1806 is the same as the processing from S501 to S506 in FIG. Further, the processing in S1807 is the same as the processing in S508.

  In step S1807, the perspective conflict determination unit 213 calculates the defocus amount for each scanning line from the image shift amount for each scanning line calculated in step S1805.

  In step S1808, the perspective conflict determination unit 213 selects a scan line to be used based on the defocus amount of each scan line calculated in step S1807 and the reliability of the image shift amount obtained in step S1806. The defocus amount is set as the used defocus amount. Then, the focus detection process ends.

  The flowchart in FIG. 19 shows a used defocus amount setting process performed by the perspective conflict determination unit 213 in S1808 in FIG. The used defocus amount setting process shown in FIG. 19 is the same as the “image shift amount” in the used image shift amount setting process shown in FIG.

  Next, the defocus amount difference threshold (predetermined threshold) setting process performed by the perspective conflict determination unit 213 in S1908 of FIG. 19 will be described using the flowchart of FIG. The processing from S2001 to S2003 is the same as the processing from S1101 to S1103 in FIG.

  In S2003, the perspective conflict determination unit 213 determines whether or not the contrast amount of the reference scanning line selected in S1903 in FIG. 19 is higher than a predetermined contrast amount. If it is higher than the predetermined contrast amount, the process proceeds to S2004. If not (lower than the predetermined contrast amount), the process proceeds to S2007.

  In S2004, the perspective conflict determination unit 213 determines whether or not the aperture 102 is larger than a predetermined aperture value. The perspective conflict determination unit 213 proceeds to S2005 when the aperture 102 is larger than the predetermined aperture value, and proceeds to S2007 when it is not (the aperture aperture is smaller than the predetermined aperture value).

  In S2005, the perspective conflict determination unit 213 determines whether or not the exit pupil distance of the photographing optical system is longer than a predetermined distance. If the distance is longer than the predetermined distance, the process proceeds to S2006, otherwise (S2007). Proceed to

  In step S2006, the perspective conflict determination unit 213 sets the defocus amount difference threshold value to α and ends this process. In S2007, the perspective conflict determination unit 213 sets the defocus amount difference threshold value to β and ends the present process. In this embodiment, the defocus amount difference thresholds α and β are set to satisfy α <β for the reason described below.

  The defocus amount can be calculated by multiplying the image shift amount by the conversion coefficient KG. However, as the conversion coefficient KG increases, the defocus amount becomes more sensitive to changes in the image shift amount, and the defocus amount variation increases. In the imaging plane phase difference AF, generally, when the aperture is narrowed, vignetting occurs due to aperture blades, the base line length between a pair of subject images is shortened, and the conversion coefficient KG is increased. Similarly, when the exit pupil distance, which is the distance from the image sensor (image plane) 201 to the exit pupil of the photographing optical system, is short, the value of the conversion coefficient KG also tends to increase. As described above, under the condition that the conversion coefficient KG is assumed to be small, a smaller defocus amount difference threshold value α is set in S2006, and only a more severe and accurate defocus amount is set as the used defocus amount. To. On the other hand, under conditions where the conversion factor KG is assumed to be large, a larger defocus amount difference threshold β is set in S2007 so that the used defocus amount is set in consideration of variations in the defocus amount.

  Note that the defocus amount difference threshold value may be set to be larger as the reference defocus amount obtained in the reference scan line is larger (when the defocus amount is larger than the predetermined defocus amount).

  In this embodiment, two defocus amount difference threshold values are provided, but three or more threshold values may be provided depending on conditions.

  Also in this embodiment, on the assumption that the main subject exists in the center of the AF area, the defocusing of the scanning line that gives a defocusing amount that matches or is close to the defocusing amount of the scanning line that is assumed to capture the main subject. The use defocus amount is calculated using only the amount. As a result, it is possible to obtain an excellent focus state with respect to the main subject while suppressing the influence of the perspective conflict of the subject in the AF area. That is, when a subject exists on the far side and the near side, neither subject is focused, it is possible to avoid the AF being completed while being blurred, and to obtain a focused state with respect to the main subject.

  Also in this embodiment, when the distance conflict is detected, the AF area is reset and the time-consuming process of performing the focus detection process again is not performed. Can be obtained.

In each of the above embodiments, the interchangeable lens imaging device has been described. However, the optical apparatus of the present invention includes a lens integrated imaging device as another embodiment. Further, the AF signal processing unit 204 may be mounted on an interchangeable lens as an optical device, and a pair of image signals in the AF area may be received from the camera 20 and the focus detection processing described in the first and second embodiments may be performed.
(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.

103 focus lens 204 AF signal processing unit 212 camera control unit 213 perspective conflict determination unit

Claims (12)

A detection amount that is one of a phase difference between a pair of image signals obtained from a focus detection region and a defocus amount of the photographing optical system based on the phase difference among image pickup elements that capture a subject image formed by the photographing optical system. A focus detection device for calculating
A plurality of first areas in the focus detection area, and a first calculation means for calculating the detection amount for each of the first areas;
A reference setting unit that selects a reference region from the plurality of first regions and sets the detection amount of the reference region as a reference detection amount;
Among the plurality of first regions, a plurality of first regions including the reference region are selected as a second region having a difference from the reference detection amount smaller than a predetermined threshold, and the detection of the plurality of second regions is performed. And a second calculating means for calculating the detection amount of the focus detection area using the amount.   The reference setting means selects a first area located in the center of the focus detection area or a predetermined central vicinity area as the reference area from among the plurality of first areas. The focus detection apparatus described. A reliability calculation means for calculating the reliability of the detection amount for each of the first regions;
3. The reference setting unit according to claim 1, wherein the reference setting unit selects, as the reference region, a first region having the reliability higher than the first reliability among the plurality of first regions. Focus detection device. A reliability calculation means for calculating the reliability of the detection amount for each of the first regions;
The second calculating means determines the first region of the plurality of first regions that has a difference with respect to the reference detection amount smaller than the predetermined threshold and the reliability is higher than a second reliability. The focus detection device according to claim 1, wherein the focus detection device is selected as the second region.   5. The focus detection apparatus according to claim 1, wherein the second calculation unit sets the predetermined threshold to be larger as the image height of the focus detection area is higher.   6. The focus detection according to claim 1, wherein the second calculation unit sets the predetermined threshold value larger as a gain applied to an output of the image sensor is larger. apparatus.   The said 2nd calculating means sets the said predetermined threshold value large, so that the contrast amount of at least one image signal among the said pair of image signals in the said reference area is small. The focus detection apparatus according to one item. The detected amount is the defocus amount,
8. The focus detection apparatus according to claim 1, wherein the second calculation unit sets the predetermined threshold value larger as a diaphragm of the photographing optical system is narrowed. 9. The detected amount is the defocus amount,
The said 2nd calculating means sets the said predetermined threshold value large, so that the distance from the said image pick-up element to the exit pupil of the said imaging optical system is short, It is characterized by the above-mentioned. Focus detection device. The detected amount is the defocus amount,
10. The focus detection apparatus according to claim 1, wherein the second calculation unit sets the predetermined threshold value to be larger as the reference detection amount is larger. The focus detection apparatus according to any one of claims 1 to 10,
An optical apparatus comprising: control means for performing focus control using the detection amount obtained by the focus detection device. A detection amount that is one of a phase difference between a pair of image signals obtained from a focus detection region and a defocus amount of the photographing optical system based on the phase difference among image pickup elements that capture a subject image formed by the photographing optical system. A computer program for causing a computer to execute a focus detection process for calculating
The focus detection process includes
A process of providing a plurality of first regions in the focus detection region and calculating the detection amount for each of the first regions;
A process of selecting a reference area from the plurality of first areas and setting the detection amount of the reference area as a reference detection amount;
A process of selecting a plurality of first areas including the reference area as a second area, wherein the difference between the plurality of first areas and the reference detection amount is smaller than a predetermined threshold;
And a process of calculating the detection amount of the focus detection region using the detection amounts of the plurality of second regions.