JP2013171251A - Focus detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detection device capable of accurately detecting the amount of defocus between the most satisfactory image plane and an estimated focal plane.SOLUTION: A focus detection device comprises: a photoelectric conversion device configured to generate a pair of image signals corresponding to a pair of images formed on an estimated focal plane by a pair of luminous fluxes passing through an exit pupil; image displacement amount detection means for detecting a relative amount of image displacement of the pair of images on the basis of the correlation degree of the pair of image signals; image displacement amount correction means for calculating the amount of corrected image displacement on the basis of the relative amount of image displacement and a predetermined amount of offset; defocus amount calculation means for calculating the amount of defocus by multiplying the amount of corrected image displacement and a predetermined conversion coefficient; and offset amount acquisition means for acquiring a predetermined amount of offset, which is determined in accordance with the difference in shapes between a pair of images by a pair of luminous fluxes passing through the exit pupil, resulting from the aberration of a photographing optical system.

Description

  The present invention relates to a focus detection apparatus using a pupil division type phase difference detection method.

  An optical system by generating a pair of image signals corresponding to a pair of images formed by a pair of focus detection light beams passing through the exit pupil of the optical system and detecting an image shift amount (phase difference) between the pair of image signals There is known a focus detection apparatus that detects a defocus amount that is a difference between the focus adjustment state of the target, that is, a planned focal plane and a detected image plane, that is, a so-called pupil division type phase difference detection type focus detection apparatus.

  In this type of pupil division type phase difference detection type focus detection device, an error may occur between the detected image plane and the best image plane (best focus plane) at the time of shooting. It has been proposed to do. For example, a defocus amount error caused by a difference between an F value (focus detection F value) of a pair of focus detection light beams used for focus detection and an F value (imaging F value) of a photographing light beam due to spherical aberration. A technique for correcting is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 57-210326

  However, it has been found that even if the defocus amount error caused by the difference between the focus detection F value and the photographing F value is corrected, another error due to spherical aberration may remain. As a result of the examination, it has been found that the cause of such an error is that the shape of the pair of images formed by the pair of focus detection light beams in the focused state becomes inconsistent due to the aberration of the optical system.

  The focus detection apparatus according to claim 1, by photoelectric conversion, a pair of image signals corresponding to a pair of images formed on a planned focal plane by a pair of light beams passing through a pair of areas of an exit pupil of a photographing optical system. Based on the photoelectric conversion device to be generated, the image shift amount detection means for detecting the relative image shift amount of the pair of images based on the correlation between the pair of image signals, and the relative image shift amount and a predetermined offset amount Image deviation amount correction means for calculating the correction image deviation amount, defocus amount calculation means for calculating the defocus amount by multiplying the correction image deviation amount by a predetermined conversion coefficient, and the aberration of the photographing optical system. And an offset amount acquisition means for acquiring a predetermined offset amount determined according to the difference in shape of the pair of images by the pair of light beams passing through the pair of areas of the exit pupil of the photographing optical system.

  The focus detection apparatus according to the present invention can accurately detect the defocus amount between the best image plane and the planned focal plane.

It is a cross-sectional view which shows the structure of a digital camera. It is a figure which shows the focus detection position on an imaging | photography screen. It is a front view which shows the detailed structure of an image pick-up element. It is a figure for demonstrating the mode of the imaging light beam which an imaging pixel receives. It is a figure for demonstrating the mode of the focus detection light beam which a focus detection pixel receives. It is a flowchart which shows operation | movement of a digital camera. It is a figure for demonstrating an image shift detection calculation process. It is the figure which showed typically how an imaging light beam and a pair of focus detection light beams converge in the vicinity of a planned focal plane. It is a figure which shows the example of distribution (point image distribution function) of the point image which an imaging light beam forms on a plan focal plane. It is a figure which shows the example of distribution (point image distribution function) of the point image which a pair of focus detection light beam forms on a plan focal plane. FIG. 6 is a diagram illustrating a subject image when a monochrome edge subject is formed on the best image plane with a pair of focus detection light beams when the photographing optical system has no aberration. FIG. 6 is a diagram illustrating a subject image formed on the best image plane by a pair of focus detection light beams when a photographing optical system with large aberration is used for a subject with black and white edges. It is a figure which shows a mode that a pair of point image distribution was displaced relatively and overlapped. FIG. 5 is a block diagram showing a processing portion related to calculation and use of an offset amount in the first embodiment. It is a figure which shows the position of the focus detection area on an imaging | photography screen. In 2nd Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram. In 3rd Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram. In 4th Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram. In 5th Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram. In 6th Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram. In 7th Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram. FIG. 20 is a block diagram showing a processing portion related to calculation and use of an offset amount in the eighth embodiment. In 9th Embodiment, it is the figure which represented the process part regarding calculation and use of offset amount with the block diagram.

<First Embodiment>
As an imaging apparatus including the focus detection apparatus according to the first embodiment of the present invention, an interchangeable lens type digital camera will be described as an example. FIG. 1 is a cross-sectional view showing the configuration of the digital camera of this embodiment. A digital camera 201 according to the present embodiment includes an interchangeable lens 202 and a camera body 203, and the interchangeable lens 202 is attached to the camera body 203 via a mount unit 204. An interchangeable lens 202 having various photographing optical systems can be attached to the camera body 203 via a mount unit 204.

  The interchangeable lens 202 includes a lens 209, a zooming lens 208, a focusing lens 210, a diaphragm 211, a lens control device 206, and the like. The lens control device 206 includes a microcomputer (not shown), a memory, a lens drive control circuit, and the like. The lens control device 206 performs drive control for adjusting the focus of the focusing lens 210 and adjusting the aperture diameter of the aperture 211, and detecting the states of the zooming lens 208, the focusing lens 210, and the aperture 211. The lens control device 206 transmits lens information and receives camera information (defocus amount, aperture value, etc.) through communication with a body control device 214 described later. The aperture 211 forms an aperture having a variable aperture diameter at the center of the optical axis in order to adjust the amount of light and the amount of blur.

  The camera body 203 includes an imaging element 212, a body control device 214, a liquid crystal display element driving circuit 215, a liquid crystal display element 216, an eyepiece lens 217, a memory card 219, an AD converter 221 and the like. In the imaging device 212, imaging pixels are arranged according to a two-dimensional array defined by rows and columns, and focus detection pixels are arranged at portions corresponding to the focus detection positions. Details of the image sensor 212 will be described later.

  The body control device 214 includes a microcomputer, a memory, a drive control circuit, and the like. The body control device 214 repeatedly performs exposure control of the image sensor 212, readout of the pixel signal from the image sensor 212, focus detection calculation based on the pixel signal of the focus detection pixel, and focus adjustment of the interchangeable lens 202, and an image. It performs signal processing, display and recording, and camera operation control. The body control device 214 communicates with the lens control device 206 via the electrical contact 213 to receive lens information and transmit camera information.

  The liquid crystal display element 216 functions as an electronic view finder (EVF). The liquid crystal display element driving circuit 215 displays a through image on the liquid crystal display element 216 based on the image signal read from the image sensor 212, and the photographer can observe the through image through the eyepiece 217. The memory card 219 is an image storage that stores image data generated based on an image signal captured by the image sensor 212.

   The AD conversion device 221 performs AD conversion on the pixel signal output from the image sensor 212 and sends it to the body control device 214. The imaging device 212 may have a configuration in which the AD conversion device 221 is incorporated.

  A subject image is formed on the imaging surface of the imaging element 212 by the light beam that has passed through the interchangeable lens 202. This subject image is photoelectrically converted by the image sensor 212, and the pixel signals of the imaging pixels and focus detection pixels are sent to the body control device 214.

  The body control device 214 calculates the defocus amount based on the pixel signal (focus detection signal) from the focus detection pixel of the image sensor 212 and sends this defocus amount to the lens control device 206. Further, the body control device 214 processes the pixel signal (imaging signal) of the imaging pixel of the imaging element 212 to generate image data, stores the image data in the memory card 219, and reads the through image signal read from the imaging element 212. Is sent to the liquid crystal display element driving circuit 215, and a through image is displayed on the liquid crystal display element 216. Further, the body control device 214 sends aperture control information to the lens control device 206 to control the aperture of the aperture 211.

  The lens control device 206 updates the lens information according to the focusing state, zooming state, aperture setting state, aperture opening F value, and the like. Specifically, the positions of the zooming lens 208 and the focusing lens 210 and the aperture value of the aperture 211 are detected, and lens information is calculated according to these lens positions and aperture values, or a lookup prepared in advance. Lens information corresponding to the lens position and aperture value is selected from the table.

  The lens control device 206 calculates a lens driving amount based on the received defocus amount, and drives the focusing lens 210 to the in-focus position according to the lens driving amount. In addition, the lens control device 206 drives the diaphragm 211 in accordance with the received diaphragm value.

  FIG. 2 is a diagram showing a focus detection position on the shooting screen, and an area for sampling an image on the shooting screen (focus detection area, focus detection) when focus detection is performed by a focus detection pixel array on the image sensor 212 described later. An example of (position) is shown. In this example, the focus detection area 101 is arranged at the center (on the optical axis) on the rectangular shooting screen 100. Focus detection pixels are linearly arranged in the longitudinal direction (horizontal direction) of the focus detection area 101 indicated by a rectangle.

  FIG. 3 is a front view showing a detailed configuration of the image sensor 212, and shows details of a pixel array in which the vicinity of the focus detection area 101 arranged in the horizontal direction in FIG. 2 is enlarged. Imaging pixels 310 are densely arranged on the imaging element 212 in a two-dimensional square lattice pattern. The imaging pixel 310 includes a red pixel (R), a green pixel (G), and a blue pixel (B), and is arranged according to a Bayer arrangement rule. In FIG. 3, focus detection pixels 315 and 316 for horizontal focus detection having the same pixel size as that of the imaging pixel 310 are alternately arranged on a straight line in the horizontal direction in which green pixels and blue pixels are supposed to be continuously arranged. Are arranged in succession.

  The shape of each microlens of the imaging pixel 310 and the focus detection pixels 315 and 316 is a shape obtained by cutting out a circular microlens originally larger than the pixel size into a square shape corresponding to the pixel size.

  As shown in FIG. 3, the imaging pixel 310 includes a rectangular microlens 10, a photoelectric conversion unit 11 in which a light receiving region is limited to a square by a light shielding mask, and a color filter. The color filters include three types of red (R), green (G), and blue (B), and have spectral sensitivity characteristics corresponding to the respective colors. In the image pickup device 212, image pickup pixels 310 having respective color filters are arranged in a Bayer array.

  The focus detection pixels 315 and 316 are provided with white filters that transmit all visible light in order to perform focus detection for all colors. The white filter has a spectral sensitivity characteristic such that the spectral sensitivity characteristics of the green pixel, the red pixel, and the blue pixel are added, and the light wavelength region exhibiting high sensitivity is each color filter in each of the green pixel, the red pixel, and the blue pixel. Includes a light wavelength region exhibiting high sensitivity.

  As shown in FIG. 3, the focus detection pixel 315 is a photoelectric conversion in which a light receiving region is limited to a left half of a square (a left half when a square is divided into two equal parts by a vertical line) using a rectangular microlens 10 and a light shielding mask. And a white filter (not shown).

  Further, as shown in FIG. 3, the focus detection pixel 316 is limited to the right half of the square (right half when the square is divided into two equal parts by a vertical line) by the rectangular microlens 10 and the light shielding mask. It comprises a photoelectric conversion unit 16 and a white filter (not shown).

  When the focus detection pixel 315 and the focus detection pixel 316 are displayed with the microlens 10 superimposed, the photoelectric conversion units 15 and 16 in which the light receiving area is limited to a half of a square by a light shielding mask are arranged in the horizontal direction.

  Further, when the remaining portion obtained by halving the square is added to the portion of the light receiving region limited to the half of the square described above, a square having the same size as the light receiving region of the imaging pixel 310 is obtained.

  In the configuration of the imaging pixel and the focus detection pixel as described above, under a general light source, the output level of the green imaging pixel and the output level of the focus detection pixel are substantially equal, and the red imaging pixel and the blue color are detected. The output level of the image pickup pixel becomes smaller than this.

  FIG. 4 is a diagram for explaining the state of the imaging light beam received by the imaging pixel 310 shown in FIG. 3, and takes a cross section of the imaging pixel array arranged in the horizontal direction. The photoelectric conversion units 11 of all the imaging pixels 310 arranged on the image sensor 212 receive the light flux that has passed through the openings of the light shielding masks arranged close to the photoelectric conversion unit 11. The shape of the light-shielding mask opening is projected by the microlens 10 of each imaging pixel 310 onto a region 97 common to all imaging pixels on the exit pupil 90 of the imaging optical system that is separated from the microlens 10 by the distance measurement pupil distance d.

  Accordingly, the photoelectric conversion unit 11 of each imaging pixel receives the light beam 71 passing through the region 97 and the microlens 10 of each imaging pixel, and corresponds to the intensity of the image formed on each microlens 10 by the light beam 71. Output a signal.

  FIG. 5 is a diagram for explaining the state of the focus detection light beam received by the focus detection pixels 315 and 316 shown in FIG. 3 in comparison with FIG. 4, and is a cross section of the focus detection pixel array arranged in the horizontal direction. Have taken.

  The photoelectric conversion units 15 and 16 of all the focus detection pixels 315 and 316 arranged on the image sensor 212 receive the light flux that has passed through the opening of the light shielding mask disposed in proximity to each of the photoelectric conversion units 15 and 16. To do. The shape of the light-shielding mask opening arranged close to the photoelectric conversion unit 15 is such that the focus detection pixel on the exit pupil 90 separated from the microlens 10 by the distance measurement pupil distance d by the microlens 10 of each focus detection pixel 315. 315 is projected onto a common area 95. Similarly, the shape of the light-shielding mask opening arranged close to the photoelectric conversion unit 16 is such that the focus detection on the exit pupil 90 separated from the microlens 10 by the distance measurement pupil distance d by the microlens 10 of each focus detection pixel 316. The image is projected onto an area 96 common to all the pixels 316. The pair of areas 95 and 96 is called a distance measuring pupil.

  Accordingly, the photoelectric conversion unit 15 of each focus detection pixel 315 receives the light beam 75 passing through the distance measuring pupil 95 and the microlens 10 of each focus detection pixel 315 and is formed on each microlens 10 by the light beam 75. A signal corresponding to the intensity of the image is output. The photoelectric conversion unit 16 of each focus detection pixel 316 receives a light beam 76 passing through the distance measuring pupil 96 and the microlens 16 of each focus detection pixel 316 and is formed on each microlens 10 by the light beam 76. A signal corresponding to the intensity of the image is output.

  A region where the distance measuring pupils 95 and 96 on the exit pupil 90 through which the light beams 75 and 76 received by the pair of focus detection pixels 315 and 316 pass is integrated on the exit pupil 90 through which the light beam 71 received by the imaging pixel 310 passes. The pair of light beams 75 and 76 are complementary to the light beam 71 on the exit pupil 90.

  In the above description, the light receiving area of the photoelectric conversion unit is regulated by the light shielding mask, but the shape of the photoelectric conversion unit itself may be the opening shape of the light shielding mask. In that case, the shading mask may be eliminated.

  In short, it is important that the photoelectric conversion unit and the distance measuring pupil have an optically conjugate relationship by the microlens.

  Further, the position of the distance measuring pupil (the distance measuring pupil distance) is generally set to be substantially the same as the exit pupil distance of the photographing optical system. When a plurality of interchangeable lenses are mounted, the distance measuring pupil distance is set to the average exit pupil distance of the plurality of interchangeable lenses.

  A large number of the pair of focus detection pixels 315 and 316 described above are alternately and linearly arranged, and the outputs of the photoelectric conversion units of the focus detection pixels are collected into a pair of output groups corresponding to the distance measurement pupil 95 and the distance measurement pupil 96. . As a result, information on the intensity distribution of the pair of images formed on the horizontal focus detection pixel array by the pair of light beams passing through the distance measuring pupil 95 and the distance measuring pupil 96 can be obtained. By applying an image shift detection calculation process (correlation calculation process, phase difference detection process), which will be described later, to this information, an image shift amount of a pair of images is detected by a so-called pupil division type phase difference detection method. Further, by performing a conversion operation using a conversion coefficient corresponding to the proportional relationship between the distance between the center of gravity of the pair of distance measurement pupils and the distance measurement pupil distance to the image shift amount, the planned imaging plane and pupil at the focus detection position are calculated. The deviation from the image plane detected by the division type phase difference detection method, that is, the defocus amount is calculated.

  In FIG. 5, for easy understanding, the pair of regions 95 and 96 are shown in a clear shape, the pair of focus detection light beams 75 and 76 are expressed in a cone shape, and the light beam has a cross section perpendicular to the optical axis 91. It is explained as if the light density is uniform on the cross section. However, in practice, the outer shapes of the pair of regions 95 and 96 are unclear depending on the aberration of the micro lens of the focus detection pixel. Further, the light density of the pair of focus detection light beams 75 and 76 in a cross section perpendicular to the optical axis 91 is not uniform, and has a distribution according to the optical characteristics of the focus detection optical system and the optical characteristics of the photographing optical system. Show.

  FIG. 6 is a flowchart showing the operation of the digital camera 201 of the present embodiment. The body control device 214 starts operation from step S110 when the power of the digital camera 201 is turned on in step S100. If it is necessary to change the aperture in step S110, the body control device 214 sends an aperture adjustment command to the lens control device 206 to cause the aperture adjustment. At the same time, the body control device 214 performs an imaging operation to thin out and read out the data of the imaging pixels 310 from the imaging element 212 and display the data on the liquid crystal display element 216. In subsequent step S120, the body control device 214 reads data of a pair of image signals corresponding to the pair of images from the focus detection pixel array.

  In step S130, the body control device 214 performs an image shift detection calculation process (correlation calculation process) based on the read data of the pair of image signals, and calculates an image shift amount.

  In step S131, the body control device 214 reads a pair of point image distribution data (a pair of point image signal data) from the lens control device 206, and performs image shift detection calculation processing (correlation) on the pair of point image distribution data. An image shift amount is calculated by performing a calculation process, and the image shift amount is set as an offset amount. The details of the pair of point image distribution data read from the lens control device 206 in step S131 will be described later. As the pair of point image distribution data, the data of the pair of image signals read in step S130 is captured. When it is assumed that focusing has been achieved in the setting of the photographing optical system (aperture F value, focusing lens position, zoom lens position) at the time (the planned focal plane matches the best image plane) This is image data representing a distribution function of a point image formed on the best image plane by a pair of focus detection light beams in this situation. The best image plane mentioned here is an image plane formed by a photographing light beam that gives an optimum image in optical design or sensory evaluation. As the best image plane, for example, an image plane with the maximum resolution, an image plane with the smallest point image distribution (an image plane with a minimum circle of confusion), and an image with the maximum MTF (Modulation Transfer Function) at a predetermined spatial frequency. There are faces.

  In step S132, the body control device 214 subtracts the offset amount calculated in step S131 from the image shift amount calculated in step S130 to calculate a corrected image shift amount. Although details will be described later, by correcting the image shift amount in this manner, the image plane detected between the pair of focus detection light fluxes formed based on the image shift amount of the pair of images and the best image plane are corrected. Errors can be eliminated or reduced.

  In step S135, the body control device 214 converts the corrected image shift amount calculated in step S132 into a defocus amount. In step S140, the body control device 214 determines whether or not the focus adjustment state of the photographing optical system is close to focusing, that is, whether or not the absolute value of the calculated defocus amount is within a predetermined value. If it is determined that it is not near the in-focus state, the process proceeds to step S150. In step S150, the body control device 214 transmits the defocus amount to the lens control device 206, and drives the focusing lens 210 of the interchangeable lens 202 shown in FIG. 1 to the in-focus position. Thereafter, the process returns to step S110 to repeat the above-described operation.

  Even when focus detection is impossible, the process branches to step S150, and the body control device 214 transmits a scan drive command to the lens control device 206, and moves the focusing lens 210 of the interchangeable lens 202 from the infinity position to the closest position. Drive to scan. Thereafter, the process returns to step S110 and the above-described operation is repeated.

  On the other hand, if it is determined in step S140 that the focus adjustment state of the photographing optical system is close to the in-focus state, the process proceeds to step S160. In step S160, the body control device 214 determines whether or not a shutter release has been performed by operating a shutter button (not shown). If it is determined that the shutter release has not been performed, the process returns to step S110 and the operation described above. Is repeated. In step S160, if the body control device 214 determines that the shutter release has been performed, in step S170, the body control device 214 causes the image pickup device 212 to perform an image pickup operation, and obtains image data from the image pickup pixels of the image pickup device 212 and all focus detection pixels. read out.

  In step S180, the body control device 214 interpolates the pixel data at each pixel position in the focus detection pixel row based on the data of the imaging pixels around the focus detection pixel. In subsequent step S190, the body control device 214 saves the image data including the imaged pixel data and the interpolated data in the memory card 219, and the process returns to step S110 and the above-described operation is repeated.

Next, details of the image shift detection calculation process (correlation calculation process) in step S130 of FIG. 6 will be described. The pair of images detected by the focus detection pixels can maintain the image displacement detection accuracy with respect to the light amount balance because the distance measurement pupils are unevenly placed by the aperture of the lens and the light amount balance may be lost. Perform a type of correlation operation. The correlation calculation of the following equation (1) is performed on a pair of data strings A1 _{1 to} A1 _M and A2 _{1 to} A2 _M (M is the number of data) corresponding to the pair of image signals read from the focus detection pixel array, A correlation amount C (k) corresponding to the degree of correlation between the pair of image signals is calculated.
C (k) = Σ | A1 _n · A2 _{n + s + k} −A2 _{n + k} · A1 _{n + s} | (1)

In equation (1), the Σ operation is accumulated for variable n. The range of the variable n is limited to a range in which data of A1 _n , A1 _{n + s} , A2 _{n + k} , A2 _{n + s + k} exists according to the image shift amount k. The image shift amount k is an integer and is a relative shift amount with the data interval of the data string as a unit. The variable s is an integer, and 1, 2,. As shown in FIG. 7A, the calculation result of Expression (1) shows that the correlation amount C (k) is minimal in the shift amount where the correlation between the pair of data is high (k = kj = 2 in FIG. 7A). become. The smaller the value of the correlation amount C (k), the higher the correlation between the pair of image signals. The correlation calculation formula is not limited to the formula (1), and any correlation calculation formula may be used as long as it calculates the correlation degree of a pair of data strings (a pair of image signals).

Next, the shift amount x that gives the minimum value C (x) with respect to the continuous correlation amount is obtained using the three-point interpolation method of Equations (2) to (5). This shift amount x corresponds to the relative image shift amount of a pair of images before correction, which will be described later.
x = kj + D / SLOP (2)
C (x) = C (kj) − | D | (3)
D = {C (k−1) −C (kj + 1)} / 2 (4)
SLOP = MAX {C (kj + 1) -C (kj), C (kj-1) -C (kj)} (5)

  Whether or not the shift amount x calculated by the equation (2) is reliable is determined as follows. As shown in FIG. 7B, when the degree of correlation between a pair of data is low, the value of the minimal value C (x) of the interpolated correlation amount increases. Therefore, when C (x) is equal to or greater than a predetermined threshold value, it is determined that the calculated shift amount has low reliability, and the calculated shift amount x is canceled. Alternatively, in order to normalize C (x) with the contrast of data, when the value obtained by dividing C (x) by SLOP that is proportional to the contrast is equal to or greater than a predetermined value, the reliability of the calculated shift amount Is determined to be low, and the calculated shift amount x is canceled. Alternatively, when SLOP that is a value proportional to the contrast is equal to or less than a predetermined value, it is determined that the subject has low contrast and the reliability of the calculated shift amount is low, and the calculated shift amount x is canceled.

  As shown in FIG. 7C, when the correlation between the pair of data is low and there is no drop in the correlation amount C (k) between the shift ranges kmin to kmax, the minimum value C (x) is obtained. In such a case, it is determined that the focus cannot be detected.

  The above is the image shift detection calculation processing in step S130 of FIG. 6, but the same image shift detection calculation processing is performed on the pair of point image data in step S131, and the image shift amount between the pair of point image data. Is calculated as an offset amount Offset, and a corrected image shift amount (x-Offset) is calculated in step S132. That is, a corrected image shift amount (x-Offset) is calculated based on the shift amount x corresponding to the relative image shift amount of the pair of images detected in step S130 and the offset amount Offset calculated in step S131. Is done.

When it is determined that the image shift amount x is reliable, the corrected image shift amount is converted into the corrected image shift amount shft according to Expression (6).
shft = PY. (x-Offset) (6)

In Expression (6), PY is a detection pitch, that is, a sampling pitch by the same kind of focus detection pixels (twice the pitch of imaging pixels). Next, the image shift amount calculated by Expression (6) is multiplied by a predetermined conversion coefficient k to convert it to a defocus amount def.
def = k · shft (7)

  Since the defocus amount calculated by Expression (7) is a defocus amount that accurately reflects the deviation between the best image plane and the planned focal plane, automatic focus adjustment is performed based on this defocus amount. By taking a picture, an image with the best image quality can be obtained.

  Next, the mechanism by which the best image plane matches the planned focal plane and the image with the best image quality can be obtained by the operation flow shown in FIG. 6 will be described in detail.

  A so-called pupil division type phase difference detection method is used to detect the amount of image misalignment between a pair of images formed by a pair of focus detection light beams and adjust the focus of the photographic optical system so that the amount of image misalignment becomes zero. The principle of focus adjustment that can achieve a state (a state where the best image plane coincides with the planned focal plane) is based on the premise that the shapes of a pair of images formed by a pair of focus detection light beams coincide with each other at the time of focusing. In other words, the image shift amount is a substitute characteristic representing the focus adjustment state. Accordingly, if the premise that the shapes of the pair of images formed by the pair of focus detection light beams coincide with each other at the time of focusing is lost, an error occurs in the focus adjustment state detected by the image shift amount accordingly.

  FIG. 8 shows a case where the best image plane is formed on the planned focal plane 98 and passes through a pair of areas 95 and 96 of the imaging light flux and the exit pupil passing through the exit pupil area 97 shown in FIGS. 4 and 5, respectively. It is the figure which showed typically how a pair of focus detection light beam which converges converges in the plan focal plane 98 vicinity. For example, if there is a point light source on the optical axis 91 in FIG. 8, a point image is formed on the optical axis 91 on the planned focal plane 98 corresponding to the point light source.

  In the case of an ideal aberration-free photographic optical system, a point image formed by a photographic light beam passing through the exit pupil region 97 is also formed by a pair of focus detection light beams passing through a pair of regions 95 and 96 of the exit pupil. Each of the point images is a complete point that does not spatially expand on the planned focal plane 98, and a pair of points formed by a pair of focus detection light beams that pass through the pair of regions 95 and 96 of the exit pupil. The spatial position of the image on the planned focal plane 98 also coincides. When a general subject is photographed using such an aberration-free photographing optical system, the shape of the pair of subject images formed on the best image plane by the pair of focus detection light beams completely coincides with each other. Since the positions of the pair of subject images also coincide, it can be guaranteed that the pair of subject images is in focus when the image shift amount of the pair of subject images is zero.

  However, when the photographing optical system has optical aberration, a point image formed by the photographing light flux passing through the exit pupil region 97 is also formed by a pair of focus detection light fluxes passing through the pair of exit pupil regions 95 and 96. Neither of the pair of point images is a perfect point that does not spatially expand on the planned focal plane 98.

  FIG. 9 shows the distribution 51 of point images (point image distribution function) formed by the photographing light beam on the planned focal plane 98 in the state shown in FIG. 8, that is, in the state where the best image plane is formed on the planned focal plane 98. An example is shown, with a large peak at the center and a symmetrical bottom at the periphery. On the other hand, FIG. 10 shows an example of the distribution of point images (point image distribution function) formed by the pair of focus detection light beams on the planned focal plane 98 in the same state, that is, in the state where the best image plane is formed on the planned focal plane 98. The solid line shows the point image distribution 55 formed by the focus detection light beam passing through the region 95, and the broken line shows the point image distribution 56 formed by the focus detection light beam passing through the region 96. 9 and 10, the horizontal axis represents the horizontal position on the planned focal plane 98, and the vertical axis represents the image intensity. The peak positions of the point image distributions 51, 55, and 56 are the center of the image plane, that is, the position at which the optical axis 91 intersects the planned focal plane 98.

  Like the point image distribution 51, the point image distributions 55 and 56 have a large peak at the center and have a base at the periphery, but the method of drawing the base is both asymmetric. While the right foot of the point image distribution 55 is large, there is almost no left foot. The left foot of the point image distribution 56 is large, while the right foot is scarce. That is, the shapes of the pair of point image distributions 55 and 56 are different from each other. Further, the pair of focus detection light beams has a complementary relationship with the photographic light beam, and the combination of the pair of focus detection light beams becomes the photographic light beam. Therefore, the sum of the point image distribution 55 and the point image distribution 56 is added. A point image distribution 51 is obtained. When the point image is formed on the optical axis (FIGS. 9 and 10), the shape of the point image distribution 51 is bilaterally symmetrical, and one of the point image distribution 55 and the point image distribution 56 is reversed left and right. Sometimes the shapes match. Incidentally, when the point image is outside the optical axis, the shape of the point image distributions 51, 55, and 56 is further deformed from the shape shown in FIGS. 9 and 10 according to the image height. The point image distribution 55 and the point image distribution 56 do not coincide with each other even when one of them is reversed left and right.

  In general, when the amount of aberration of the photographing optical system is small or good, in the shape of the point image distributions 51, 55, and 56 on the best image plane, the spread of the skirt portion is small compared to the size of the peak portion. The point image distributions 55 and 56 have almost the same shape, and the positions of the pair of point images are almost the same.

  In general, the distribution function of an object image formed by an imaging optical system with aberration is a combo of the point image distribution function formed by an imaging optical system with aberration to the distribution function of an object image formed without aberration. It will be a lucrative one.

  Therefore, when photographing a general subject using a photographing optical system having a small amount of aberration or good, the shape of the pair of subject images formed on the best image plane by the pair of focus detection light beams almost coincides with each other. The positions of the pair of subject images also coincide. Therefore, even if focus detection is performed based on the premise that focusing is performed when the image shift amount of the pair of subject images is 0, no large error occurs.

  However, when photographing a general subject using a photographing optical system having a large amount of aberration, the shape of the pair of subject images formed on the best image plane by the pair of focus detection light beams does not match. Therefore, if focus detection is performed based on the premise that the subject is in focus when the image shift amount of the pair of subject images is 0, a large error occurs.

  FIG. 11 shows a subject image when a black-and-white edge subject is formed on the best image plane with a pair of focus detection light beams when the photographing optical system has no aberration, and the focus detection that passes through the region 95 in FIG. The light beam forms a subject image 65, and the focus detection light beam passing through the region 96 forms a subject image 66. The position of the edge portion 45 of the subject image 65 and the position of the edge portion 46 of the subject image 66 coincide with each other. In such a case, the amount of image deviation can be determined by any image displacement detection calculation (correlation calculation). Is calculated as 0.

  On the other hand, FIG. 12 shows a subject image formed on the best image plane by a pair of focus detection light beams when a photographing optical system with large aberration is used for a subject with the same black and white edge as FIG. Further, it is assumed that the distribution of a pair of point images formed on the best image plane by the pair of focus detection light beams that have passed through the photographing optical system is represented by point image distribution functions 55 and 56 shown in FIG. The subject image 67 is an edge image formed by the focus detection light beam passing through the region 95, and is an image obtained by convolving the point image distribution function 55 with the subject image 65 in the case of no aberration. The subject image 68 is an edge image formed by a focus detection light beam passing through the region 96, and is an image obtained by convolving the point image distribution function 56 with the subject image 66 in the case of no aberration.

  The pair of subject images 67 and 68 are originally the same subject image, but the pair of point image distributions formed by the pair of focus detection light beams are not the same, that is, the shape of the pair of point images is different. The shapes of the images are greatly different from each other. For example, the shape of the upper portion 41 of the edge portion 47 of the subject image 67 and the shape of the upper portion 42 of the edge portion 48 of the subject image 68 are greatly different. The shape of the lower portion 43 of the edge portion 47 of the subject image 67 and the shape of the lower portion 44 of the edge portion 48 of the subject image 68 are greatly different. In the state where the best image plane coincides with the planned focal plane, the detected image shift amount does not become zero even when the image shift detection is performed on the pair of subject images 67 and 68 having different shapes. For example, when the image shift amount Δ (≠ 0) is calculated in this state, the image plane corresponding to the image shift amount Δ is, for example, a surface 99 in FIG.

  The cause of such an error (image shift amount Δ) is that, as described above, the pair of point image distributions formed by the pair of focus detection light beams on the best image plane are not the same, that is, the shape of the pair of point images is the same. There is a difference. As described below, the error (image shift amount Δ) can be calculated in advance based on the difference in the shape of the pair of point image distributions formed by the pair of focus detection light beams on the best image plane.

Specifically, if the pair of point image distributions 55 and 56 formed by the pair of focus detection light beams on the best image plane shown in FIG. The image shift amount obtained by performing the shift detection calculation can be regarded as the image shift amount Δ. In FIG. 10, the peak positions of the point image distributions 55 and 56 coincide with each other, but when the point image distributions 55 and 56 are relatively displaced by an image shift amount Δ, they are superimposed as shown in FIG. Note that the image shift amount Δ varies depending on the type of image shift detection calculation (correlation calculation) for calculating the image shift amount. For example, since the image shift amount Δ1 calculated using the correlation calculation of Expression (1) does not match the image shift amount Δ2 calculated using the correlation calculation of Expression (8), the body control device 214 uses the subject. It is necessary to calculate the image shift amount Δ using the same image shift detection calculation formula (correlation calculation formula) used for image shift detection of an image.
C (k) = Σ | A1 _n −A2 _{n + k} | (8)

  Since the error (image shift amount Δ) can be calculated in this way, the corrected image is obtained by subtracting the offset amount from the image shift amount obtained based on the subject image, using the image shift amount Δ as an offset amount. If the shift amount is calculated, the corrected image shift amount becomes 0 when the best image plane matches the planned focal plane.

  Accordingly, the data of the pair of point image distributions 55 and 56 (FIG. 10) formed by the pair of focus detection light beams on the best image plane when the planned focal plane and the best image plane coincide with each other are calculated in advance, and the look It is stored in the lens control device of the interchangeable lens as an up table (point image distribution data table). A pair of point image distributions 55 and 56 when the planned focal plane and the best image plane coincide with each other include optical design information (such as a microlens) of the focus detection optical system, an aperture F value of the photographing optical system, a focus lens position, It is calculated in advance based on optical design information (lens curvature, lens refractive index, inter-lens spacing, aperture diameter, etc.) of the photographing optical system using the zoom lens position as a parameter. The lens control device 206 selects the corresponding pair of point image distributions 55 and 56 from the lookup table based on the detected aperture F value, focus lens position, and zoom lens position, and sends them to the camera body 203. The body control device 214 of the camera body 203 performs an image shift calculation process on the data of the pair of point image distributions 55 and 56 received from the camera body 203 to calculate the image shift amount, thereby obtaining the best image plane and the expected focus. An offset amount for matching the surface can be obtained.

  FIG. 14 is a block diagram showing a processing portion related to the calculation and use of the offset amount in the first embodiment of the present invention described above.

  In the upper diagram of FIG. 14, in the first step, that is, the manufacturing stage, the point image distribution data table is written from the point image distribution data table generation device to the memory inside the lens control device 206 of the interchangeable lens 202. This will be described in detail. First, lens type identification information is sent from the lens control device 206 of the interchangeable lens 202 to the point image distribution data table generation device. The memory of the point image distribution data table generation device stores in advance optical design information of the photographing optical system (various interchangeable lenses) and optical design information of the focus detection optical system (such as a micro lens). Based on the optical design information of the interchangeable lens and the optical design information of the focus detection optical system corresponding to the lens type identification information received by the control device of the point spread data table generation device, the aperture F value, the focus lens position, and the zoom lens position Depending on the combination, a pair of point image distribution data in the arrangement direction (horizontal direction) of the focus detection pixels in the center of the screen, that is, in the focus detection area 101 in a state where the best image plane coincides with the planned focal plane, Calculated by the control device. The above calculation processing is performed by sequentially changing the combination of the aperture F value, the focus lens position, and the zoom lens position, and the calculated point image distribution data and the corresponding aperture F value, focus lens position, and zoom lens position information A point image distribution data table is created by the control device. Finally, the point image distribution data table generated on the point image distribution data table generation device side is sent to the interchangeable lens 202 side and stored as a point image distribution data table in the memory inside the lens control device 206 of the interchangeable lens 202. Is done.

  In the lower view of FIG. 14, the interchangeable lens 202 is attached to the camera body 203 in the second step, that is, in the use stage. As described above, the point image distribution data table is stored on the interchangeable lens 202 side. Based on the set aperture F value, focus lens position, and zoom lens position information, a pair of point image distribution data corresponding to the state of the photographing optical system at that time is obtained from the point image distribution data table by the lens controller 206. It is selected and sent to the body control device 214 of the camera body 203. The body control device 214 of the camera body 203 performs a predetermined image shift detection calculation (formulas (1) to (5)) on the focus detection pixel data to calculate an image shift amount. The body control device 214 of the camera body 203 calculates the offset amount by performing the same image shift detection calculation on the pair of point image distribution data received from the lens control device 206 of the interchangeable lens 202. Then, the body control device 214 corrects the image shift amount by subtracting the offset amount from the image shift amount.

  In calculating a pair of point image distribution data based on the optical design information of the interchangeable lens and the optical design information of the focus detection optical system, a well-known ray tracing technique is used, and a large number of light rays emitted from the point light source are used. Point image distribution data can be obtained by calculating and summing which positions on the planned focal plane pass through a pair of regions in the photographing optical system.

  In the above-described point image distribution data table, the point image distribution data is a pair of data indicating waveforms represented by the solid line 55 and the broken line 56 in FIG. The data format of the point image distribution data may be any data format as long as it can express the relationship between the position on the image plane and the intensity. The simplest data format is a data format in which the point image distributions 55 and 56 are sampled at a predetermined sampling pitch and the sampling position and intensity are paired. The sampling pitch information may be transmitted from the lens control device 206 of the interchangeable lens 202 to the body control device 214 of the camera body 203, or between the lens control device 206 of the interchangeable lens 202 and the body control device 214 of the camera body 203. It may be set to a predetermined value by an agreement. The body control device 214 of the camera body 203 that has received the point image distribution data in such a data format performs an image shift detection operation on the point image distribution data and is expressed in sampling pitch units in the point image distribution data format. An image shift amount is calculated. Furthermore, the offset amount Offset in Expression (6) is calculated by converting the image shift amount into an image shift amount in units of an image sampling pitch (twice the imaging pixel pitch) of the focus detection pixels.

  It should be noted that specific data indicating that the correction of the offset amount is unnecessary may be determined as the point image distribution data between the lens control device 206 of the interchangeable lens 202 and the body control device 214 of the camera body 203. . In this way, when the body control device 214 of the camera body 203 receives the specific data as point spread data, the offset amount calculation process is skipped and the offset amount Offset = 0 in step S131 of FIG. be able to.

  Further, instead of creating a point image distribution data table each time according to the lens type identification information by the control device of the point image distribution data table generation device, point image distribution data tables for all types of interchangeable lenses 202 are stored in advance. It is good also as making it. At this time, the control device of the point image distribution data table generation device selects a point image distribution data table corresponding to the lens type identification information and sends it to the interchangeable lens.

  Further, instead of the point image distribution data table being written into the lens control device 206 of the interchangeable lens 202 by the control device of the point image distribution data table generating device, the point image corresponding to the type of the interchangeable lens 202 at the time of manufacturing the interchangeable lens 202. A memory device that stores a distribution data table in advance may be mounted on the interchangeable lens 202.

  In the focus detection apparatus of the first embodiment, the image shift amount calculated in the focus detection area arranged at the center of the screen is accurately corrected according to the aberration characteristics of the interchangeable lens, and the best image plane of the interchangeable lens is obtained. It is possible to accurately detect the amount of defocus between the planned focal plane.

Second Embodiment
The second embodiment is an embodiment of the present invention when the focus detection areas are not limited to the center of the screen but are present at a plurality of positions.

  FIG. 15 is a diagram showing the position of the focus detection area on the shooting screen of the second embodiment, and the focus detection area is located at 25 locations on the center (on the optical axis) and in the horizontal and vertical directions on the rectangular shooting screen 100. 102 is arranged. Focus detection pixels are linearly arranged in the longitudinal direction (horizontal direction) of the focus detection area 102 indicated by a rectangle. When a plurality of focus detection areas are arranged over the entire screen in this way, a pair of focus detections are performed when the best image plane matches the planned focal plane according to the position of the focus detection area and the direction of the focus detection area. Since the point image distribution formed by the light flux also changes according to the position of the focus detection area and the direction of the focus detection area, it is necessary to prepare a point image distribution data table corresponding to the position of the focus detection area and the direction of the focus detection area. is there.

  FIG. 16 is a block diagram showing processing portions related to calculation and use of an offset amount in the second embodiment.

  In the upper diagram of FIG. 16, in the first step, that is, the manufacturing stage, the point image distribution data table is written to the interchangeable lens from the point image distribution data table generating device. First, lens type identification information is sent from the interchangeable lens to the point image distribution data table generating device. The optical design information of various interchangeable lenses and the optical design information of a focus detection optical system (such as a microlens) are stored in advance in the point image distribution data table generation device, and the optical of the interchangeable lens corresponding to the received lens type identification information. Based on the design information and the optical design information of the focus detection optical system, the best image plane and the planned focus at each image height position according to the combination of the image height and the detection direction in addition to the aperture F value, the focus lens position, and the zoom lens position. A pair of point image distribution data in the focus detection direction in a state where the surfaces coincide is calculated. Here, the image height is the distance from the center position of the screen to the position where the point image distribution data is calculated, and the detection direction is a point image when the straight line connecting the calculated position and the screen center position is based on the angle. This is the direction in which the distribution data is calculated.

  The above calculation process is performed by sequentially changing the combination of the aperture F value, the focus lens position, the zoom lens position, and the image height and the focus detection direction, and the calculated point image distribution data, the corresponding aperture F value, and the focus lens position. The point image distribution data table is created by combining the zoom lens position and the information of the image height and the focus detection direction. The point image distribution data table finally generated on the point image distribution data table generation device side is sent to the interchangeable lens side and stored as a point image distribution data table.

  In the lower view of FIG. 16, in the second step, that is, in the use stage, the interchangeable lens is mounted on the camera body.

  The camera body has a selection means (selected by a selection operation by the user) for selecting one focus detection area from the 25 focus detection areas shown in FIG. 15, and the position information of the selected focus detection area is displayed. Send to interchangeable lens. The position information of the focus detection area includes the distance from the screen center position to the focus detection area, that is, the image height and the focus detection direction. The focus detection direction is represented by an angle obtained by measuring the arrangement direction of the focus detection pixels with reference to a straight line connecting the focus detection area and the screen center.

  There is a point image distribution data table on the interchangeable lens side, and based on the set aperture F value, focus lens position, zoom lens position information, and the image height and detection direction received from the camera body, the photographing optical system at that time A pair of point image distribution data corresponding to the state is selected from the point image distribution data table and sent to the camera body.

  In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data of the selected focus detection area to calculate an image shift amount. Further, the same image shift detection calculation is performed on the pair of point image distribution data received from the interchangeable lens to calculate an offset amount corresponding to the selected focus detection area. Then, the image deviation amount of the selected focus detection area is corrected by subtracting the offset amount from the image deviation amount.

  In the focus detection apparatus of the second embodiment, the image shift amount calculated in an arbitrary focus detection area is determined according to the aberration characteristics of the interchangeable lens even when the focus detection area is not limited to the center of the screen and exists at a plurality of positions. Therefore, the defocus amount between the best image plane of the interchangeable lens and the planned focal plane can be accurately detected.

  In addition to preparing the point image distribution data table according to the image height and the detection direction as described above, the point image distribution data table may be set to correspond to the spectral sensitivity characteristic of the focus detection pixel. For example, when two types of camera bodies have different spectral sensitivity characteristics of the focus detection pixels, for example, when one is the spectral sensitivity characteristic of the white filter and the other is the spectral sensitivity characteristic of the green filter (G). The point image distribution data table is prepared according to a plurality of spectral sensitivity characteristics, and the point sensitivity image corresponding to the spectral sensitivity characteristics is transmitted from the camera body to the interchangeable lens by transmitting the spectral sensitivity characteristics of the focus detection pixels of the camera body. The distribution data may be received by the camera body from the interchangeable lens.

<Third Embodiment>
The third embodiment is an embodiment of the present invention which is obtained by actually measuring point image distribution data through an imaging optical system of an interchangeable lens.

  FIG. 17 is a block diagram showing a processing portion related to calculation and use of an offset amount in the third embodiment.

  In the upper diagram of FIG. 17, in the first step, that is, the manufacturing stage, the interchangeable lens is attached to the adjustment device (point image distribution data table generation device). The adjustment device (point image distribution data table generation device) includes the same image sensor as the camera body, and can be attached to an interchangeable lens via a lens mount. The distance from the lens mount of the adjustment device (point image distribution data table generation device) to the imaging element surface (planned focal plane) is the same as that of the camera body. In a state where the interchangeable lens is mounted on the adjustment device (point image distribution data table generation device), the image of the point light source passes through the imaging optical system of the interchangeable lens on the image sensor (focus detection) of the adjustment device (point image distribution data table generation device). Formed on the pixel array).

  At this time, the distance from the interchangeable lens to the point light source is adjusted as follows. First, a predetermined test chart is arranged instead of the point light source, and the distance to the test chart is roughly adjusted according to the aperture F value, the focus lens position, and the zoom lens position of the imaging optical system of the interchangeable lens. Next, the distance to the test chart is finely adjusted based on the data of the imaging pixels of the imaging device so that the image quality of the test chart is the best. The state in which the image quality of the test chart is the best indicates, for example, a state in which the resolution of the image is maximum or the contrast of the image is maximum. As a result, the best image plane coincides with the planned focal plane (imaging element plane). Finally, a point light source is placed at the distance of the test chart. Information about the aperture F value, focus lens position, and zoom lens position of the imaging optical system of the interchangeable lens is also sent to the adjustment device (point image distribution data table generation device) side. On the adjustment device (point image distribution data table generation device) side, a pair of point image distribution data obtained as measured values from the received information on the aperture F value, focus lens position, and zoom lens position and the data of the focus detection pixel array. Are stored in relation to each other. By performing the above processing by changing the aperture F value, the focus lens position, and the zoom lens position of the photographing optical system, a point image distribution data table is generated on the adjustment device (point image distribution data table generation device) side. Thus, it is sent to the interchangeable lens side and stored as a point image distribution data table.

  In the lower diagram of FIG. 17, the interchangeable lens is attached to the camera body in the second step, that is, in the use stage. The point image distribution data table on the interchangeable lens side stores a pair of point image distribution data (actual measurement values) formed by a pair of focus detection light beams on the best image plane when the planned focal plane coincides with the best image plane. ing. The interchangeable lens sequentially selects a pair of point image distribution data from the point image distribution data table based on the aperture F value, the focus lens position, and the zoom lens position, and sends them to the camera body.

  In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data to calculate an image shift amount. Further, the same image shift detection calculation is performed on the pair of point image distribution data received from the interchangeable lens to calculate the offset amount. Then, the image shift amount is corrected by subtracting the offset amount from the image shift amount.

  In the focus detection apparatus of the third embodiment, since the offset amount is calculated based on a pair of measured point image distribution data, even when there is an individual difference in the aberration characteristics of the imaging optical system of the interchangeable lens. Correct the amount of image deviation calculated in the focus detection area according to individual differences in the aberration characteristics of the interchangeable lens, and accurately detect the defocus amount between the best image plane of the interchangeable lens and the planned focal plane. Can do.

  When it is difficult to actually measure a pair of point image distribution data in all combinations of the aperture F value, the focus lens position, and the zoom lens position, in combination with the first embodiment, a representative aperture F value, focus lens position, A pair of point image distribution data is actually measured in the combination of the zoom lens positions, and the pair of point image distribution data obtained by calculation from the optical design information in the first embodiment is calibrated based on the actual measurement values. Good.

<Fourth embodiment>
In the fourth embodiment, instead of calculating the offset amount by sending point spread data from the interchangeable lens to the camera body and performing image shift detection calculation processing on the point spread data received on the camera body side, it is exchanged in advance. The offset amount obtained by performing image shift detection calculation processing on the point image distribution data on the lens side is stored as a table, the offset amount is sent from the interchangeable lens to the camera body, and the focus detection pixel data is sent on the camera body side. 10 is an embodiment of the present invention in which an image shift amount calculated based on the offset amount received from an interchangeable lens is corrected.

  FIG. 18 is a block diagram showing a processing portion related to calculation and use of an offset amount in the above-described fourth embodiment of the present invention.

  In the upper diagram of FIG. 18, in the first step, that is, in the manufacturing stage, the offset amount table is written from the offset amount table generating device to the interchangeable lens. First, lens type identification information is sent from the interchangeable lens to the offset amount table generating device. The offset table generation device stores optical design information of various interchangeable lenses and optical design information of a focus detection optical system (such as a micro lens) in advance, and the optical design information of the interchangeable lens corresponding to the received lens type identification information. And a pair of focus detection pixels in the direction in which the best image plane coincides with the planned focal plane according to the combination of the aperture F value, the focus lens position, and the zoom lens position based on the optical design information of the focus detection optical system. Is calculated. Next, the same image shift detection calculation processing as the image shift detection calculation processing performed on the focus detection pixel data in the camera body is performed on the calculated pair of point image distribution data, and the offset amount corresponding to the pair of point image distribution data is calculated. To do.

  The above calculation processing is performed by sequentially changing the combination of the aperture F value, the focus lens position, and the zoom lens position, and the calculated offset amount is combined with the corresponding information on the aperture F value, the focus lens position, and the zoom lens position. Create an offset amount table. The offset amount table finally generated on the offset amount table generating device side is sent to the interchangeable lens side and stored as an offset amount table.

  In the lower diagram of FIG. 18, the interchangeable lens is attached to the camera body in the second step, that is, in the use stage. There is an offset amount table on the interchangeable lens side, and an offset amount corresponding to the state of the photographing optical system at that time is selected from the offset amount table based on information on the set aperture F value, focus lens position, and zoom lens position. Sent to the camera body. In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data to calculate an image shift amount. Then, the image shift amount is corrected by subtracting the offset amount received from the interchangeable lens from the image shift amount.

  In the offset amount table described above, the data format of the offset amount is data representing the amount of image shift on the image plane in units of μm, for example. The unit information of the offset amount may be transmitted from the interchangeable lens to the camera body, or may be determined in advance by an agreement between the interchangeable lens and the camera body. The camera body that has received the offset amount determined in such a unit converts the offset amount into an offset amount of the sampling pitch of the image by the focus detection pixel (twice the imaging pixel pitch). The offset amount Offset is calculated. In addition, the offset amount table generating device calculates the offset amount based on the point image distribution data each time according to the lens type identification information and creates an offset amount table in advance. May be performed in advance to create an offset amount table, and an offset amount table corresponding to the lens type identification information may be sent to the interchangeable lens. Also, instead of writing the offset amount table from the offset amount table generating device to the interchangeable lens, a memory device that pre-stores an offset amount table corresponding to the type of the interchangeable lens when the interchangeable lens is manufactured is mounted on the interchangeable lens. Also good.

  In the focus detection apparatus of the fourth embodiment, the image shift amount calculated based on the focus detection pixel data in the focus detection area is accurately corrected according to the aberration characteristics of the interchangeable lens, and the best image plane of the interchangeable lens is scheduled. The defocus amount between the focal planes can be accurately detected.

<Fifth Embodiment>
In the fifth embodiment, offset values corresponding to the definitions of a plurality of best image planes are stored in advance as a table on the interchangeable lens side, and the camera body sends the best image plane type to the interchangeable lens. This is an embodiment of the present invention in which an offset amount corresponding to the type is sent from the interchangeable lens to the camera body, and on the camera body side, the image shift amount calculated based on the focus detection pixel data is corrected by the offset amount received from the interchangeable lens. This is to cope with a change in the position (optical axis direction) of the best image plane depending on how the best image plane is defined. For example, as the definition of a plurality of best image planes, the image plane with the maximum resolution, the image plane with the smallest point image distribution (image plane with the minimum circle of confusion), and the MTF (Modulation Transfer Function) with a predetermined spatial frequency are maximized There are image planes. Which definition defines the best image plane may be determined by the designer or user, and the camera body is automatically determined depending on whether the subject is, for example, a landscape or a document. May be.

  FIG. 19 is a block diagram showing a processing portion related to calculation and use of an offset amount in the above-described fifth embodiment of the present invention.

  In the upper diagram of FIG. 19, in the first step, that is, the manufacturing stage, the offset amount table is written to the interchangeable lens from the offset amount table generating device. First, lens type identification information is sent from the interchangeable lens to the offset amount table generating device. The offset table generation device stores optical design information of various interchangeable lenses and optical design information of a focus detection optical system (such as a micro lens) in advance, and the optical design information of the interchangeable lens corresponding to the received lens type identification information. In accordance with the combination of the aperture F value, the focus lens position, the zoom lens position and a plurality of best image plane definitions based on the optical design information of the focus detection optical system, A pair of point image distribution data in the arrangement direction of the focus detection pixels is calculated. Next, the same image shift detection calculation processing as the image shift detection calculation processing performed on the focus detection pixel data in the camera body is performed on the calculated pair of point image distribution data, and the offset amount corresponding to the pair of point image distribution data is calculated. To do.

  The above calculation process is performed by sequentially changing the combination of the aperture F value, the focus lens position, the zoom lens position and the definitions of the plurality of best image planes, and the calculated offset amount, the corresponding aperture F value, the focus lens position, the zoom An offset amount table is created by combining the lens position and the type information of the best image plane. The offset amount table finally generated on the offset amount table generating device side is sent to the interchangeable lens side and stored as an offset amount table.

  In the lower part of FIG. 19, the interchangeable lens is mounted on the camera body in the second step, that is, in the use stage. The type of the best image plane adopted by the camera body is selected from the camera body to the interchangeable lens and transmitted to the interchangeable lens. There is an offset amount table on the interchangeable lens side, and based on the set aperture F value, focus lens position, and zoom lens position information, the offset according to the state of the photographing optical system at that time and the type of the best image plane received The quantity is selected from the offset quantity table and sent to the camera body. In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data to calculate an image shift amount. Then, the image shift amount is corrected by subtracting the offset amount received from the interchangeable lens from the image shift amount.

  In the focus detection apparatus of the fifth embodiment, the image shift amount calculated based on the focus detection pixel data in the focus detection area is determined according to the definition of the best image plane adopted by the camera body and the aberration characteristics of the interchangeable lens. It is possible to accurately correct and accurately detect the defocus amount between the best image plane of the interchangeable lens and the planned focal plane.

<Sixth Embodiment>
In the sixth embodiment, offset values corresponding to a plurality of image shift detection calculations (correlation calculations) are stored as a table on the interchangeable lens side in advance, and the type of image shift detection calculation used by the camera body is sent to the interchangeable lens. The offset amount corresponding to the type of the image shift detection calculation is sent from the interchangeable lens to the camera body, and the image shift amount calculated based on the focus detection pixel data is corrected by the offset amount received from the interchangeable lens on the camera body side. It is an embodiment of the invention. In addition to the equations (1) and (8), many image displacement detection operations have been proposed for conventional image displacement detection operations (correlation operations). When the shapes of the pair of images match, there is almost no difference in image displacement calculated by the image displacement detection calculation, but when the mismatch between the shapes of the pair of images becomes large as shown in FIG. A difference in the calculated image shift amount is caused by a difference in detection calculation. Therefore, it is necessary to adjust the offset amount for matching the best image plane with the planned focal plane in accordance with the type of image shift detection calculation.

  FIG. 20 is a block diagram showing a processing portion related to calculation and use of an offset amount in the above-described sixth embodiment of the present invention.

  In the upper diagram of FIG. 20, in the first step, that is, in the manufacturing stage, the offset amount table is written in the interchangeable lens from the offset amount table generating device. First, lens type identification information is sent from the interchangeable lens to the offset amount table generating device. The offset table generation device stores optical design information of various interchangeable lenses and optical design information of a focus detection optical system (such as a micro lens) in advance, and the optical design information of the interchangeable lens corresponding to the received lens type identification information. And a pair of focus detection pixels in the direction in which the best image plane coincides with the planned focal plane according to the combination of the aperture F value, the focus lens position, and the zoom lens position based on the optical design information of the focus detection optical system. Is calculated. Next, a plurality of image shift detection calculation processes are performed on the calculated pair of point image distribution data, and a plurality of offset amounts corresponding to the plurality of image shift calculation processes are calculated corresponding to the pair of point image distribution data.

  The above calculation processing is performed by sequentially changing the combination of the aperture F value, the focus lens position, and the zoom lens position, and the calculated offset amount, the corresponding aperture F value, the focus lens position, the zoom lens position, and the image shift calculation An offset amount table is created by combining the processing type information. The offset amount table finally generated on the offset amount table generating device side is sent to the interchangeable lens side and stored as an offset amount table.

  In the lower part of FIG. 20, the interchangeable lens is attached to the camera body in the second step, that is, in the use stage. The type identification information of the image shift detection calculation processing employed in the camera body is transmitted from the camera body to the interchangeable lens. There is an offset amount table on the interchangeable lens side. Based on the set aperture F value, focus lens position, and zoom lens position information, the state of the photographing optical system at that time and the type of received image shift calculation processing are selected. The offset amount is selected from the offset amount table and sent to the camera body. In the camera body, an image shift amount is calculated by performing an image shift detection operation on the focus detection pixel data. Then, the image shift amount is corrected by subtracting the offset amount received from the interchangeable lens from the image shift amount.

  In the focus detection apparatus of the sixth embodiment, the image shift amount calculated based on the focus detection pixel data in the focus detection area is converted into the type of image shift detection calculation processing employed in the camera body and the aberration characteristics of the interchangeable lens. Accordingly, the defocus amount between the best image plane of the interchangeable lens and the planned focal plane can be accurately detected.

<Seventh embodiment>
In the seventh embodiment, offset amounts corresponding to a plurality of focus detection optical systems are stored in advance on the interchangeable lens side as a table, the camera body sends the type of focus detection optical system to the interchangeable lens, and the focus detection optical system This is an embodiment of the present invention in which an offset amount corresponding to the type of lens is sent from the interchangeable lens to the camera body, and the image displacement amount calculated based on the focus detection pixel data is corrected by the offset amount received from the interchangeable lens on the camera body side. .

  As described above, the focus detection optical system mainly includes a microlens and a photoelectric conversion unit. However, depending on differences in the curvature, refractive index, size, focal length, etc. of the microlens, optical aberration and aberration due to diffraction are present. In response to this, the state of the pair of focus detection light beams also changes. If the state of the pair of focus detection light fluxes changes, the pair of point image distribution data when the best image plane coincides with the planned focal plane also changes. Therefore, it is necessary to adjust the offset amount according to the type of the focus detection optical system. is there.

  FIG. 21 is a block diagram showing a processing part related to calculation and use of an offset amount in the above-described seventh embodiment of the present invention.

  In the upper diagram of FIG. 21, in the first step, that is, the manufacturing stage, the offset amount table is written from the offset amount table generating device to the interchangeable lens. First, lens type identification information is sent from the interchangeable lens to the offset amount table generating device. In the offset amount table generation device, optical design information of various interchangeable lenses and optical design information (information on microlenses) of a plurality of focus detection optical systems are stored in advance, and the interchangeable lens corresponding to the received lens type identification information is stored. Based on the optical design information and the optical design information of the plurality of focus detection optical systems, the best image plane matches the planned focal plane according to the combination of the aperture F value, the focus lens position, the zoom lens position, and the plurality of focus detection optical systems. In this state, a pair of point image distribution data in the arrangement direction of the focus detection pixels is calculated. Next, the same image shift detection calculation processing as the image shift detection calculation processing performed on the focus detection pixel data in the camera body is performed on the calculated pair of point image distribution data, and the offset amount corresponding to the pair of point image distribution data is calculated. To do.

  The above-mentioned calculation processing is performed by sequentially changing the combination of the aperture F value, the focus lens position, the zoom lens position and the plurality of focus detection optical systems, and the calculated offset amount, the corresponding aperture F value, the focus lens position, An offset amount table is created by combining the zoom lens position and the type information of the focus detection optical system. The offset amount table finally generated on the offset amount table generating device side is sent to the interchangeable lens side and stored as an offset amount table.

  In the lower diagram of FIG. 21, the interchangeable lens is attached to the camera body in the second step, that is, in the use stage. The camera body transmits information on the type of the focus detection optical system to the interchangeable lens so that an offset amount corresponding to the type of the focus detection optical system employed in the camera body is selected by the interchangeable lens. There is an offset amount table on the interchangeable lens side. Based on the set aperture F value, focus lens position, and zoom lens position information, the state of the photographing optical system at that time and the type of received focus detection optical system The offset amount is selected from the offset amount table and sent to the camera body. In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data to calculate an image shift amount. Then, the image shift amount is corrected by subtracting the offset amount received from the interchangeable lens from the image shift amount.

  In the focus detection apparatus of the seventh embodiment, the image shift amount calculated based on the focus detection pixel data in the focus detection area is converted into the type of focus detection optical system incorporated in the camera body and the aberration characteristics of the interchangeable lens. Accordingly, the defocus amount between the best image plane of the interchangeable lens and the planned focal plane can be accurately detected.

<Eighth Embodiment>
The eighth embodiment is an embodiment of the present invention in which the offset amount is obtained by actually measuring through an imaging optical system of an interchangeable lens.

  FIG. 22 is a block diagram showing processing portions related to calculation and use of an offset amount in the eighth embodiment.

  In the upper diagram of FIG. 22, the interchangeable lens is attached to the adjusting device (offset amount table generating device) in the first step, that is, the manufacturing stage. The adjustment device (offset amount table generation device) includes the same image sensor as the camera body, and can be attached to an interchangeable lens via a lens mount. The distance from the lens mount of the adjusting device (offset amount table generating device) to the imaging element surface (planned focal plane) is the same as that of the camera body. In a state where the interchangeable lens is mounted on the adjustment device (offset amount table generation device), the image of the point light source passes through the imaging optical system of the interchangeable lens on the imaging device (on the focus detection pixel array) of the adjustment device (offset amount table generation device). Formed.

  At this time, the distance from the interchangeable lens to the point light source is adjusted as follows. First, a predetermined test chart is arranged instead of the point light source, and the distance to the test chart is roughly adjusted according to the aperture F value, the focus lens position, and the zoom lens position of the imaging optical system of the interchangeable lens. Next, the distance to the test chart is finely adjusted based on the data of the imaging pixels of the imaging device so that the image quality of the test chart is the best. As a result, the best image plane coincides with the planned focal plane (imaging element plane). Finally, a point light source is placed at the distance of the test chart. In this state, the adjustment device (offset amount table generation device) performs image shift detection calculation processing performed on the focus detection pixel data in the camera body with respect to a pair of point image distribution data obtained as actual measurement values from the focus detection pixel array data. The same image shift detection calculation processing is performed, and an offset amount corresponding to a pair of point image distribution data is calculated.

  Information on the aperture F value, focus lens position, and zoom lens position of the imaging optical system of the interchangeable lens is also sent to the adjustment device (offset amount table generation device) side. On the adjustment device (offset amount table generating device) side, the received aperture F value, focus lens position, zoom lens position information and the offset amount obtained as an actual measurement value are stored in association with each other. By performing the above processing by changing the aperture F value, focus lens position, and zoom lens position of the photographing optical system, an offset amount table is generated on the adjustment device (offset amount table generating device) side, and finally an interchangeable lens. Sent to the side and stored as an offset amount table.

  In the lower diagram of FIG. 22, the interchangeable lens is attached to the camera body in the second step, that is, in the use stage. There is an offset amount table on the interchangeable lens side, and an offset amount corresponding to the state of the photographing optical system at that time is selected from the offset amount table based on information on the set aperture F value, focus lens position, and zoom lens position. Sent to the camera body. In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data to calculate an image shift amount. Then, the image shift amount is corrected by subtracting the offset amount received from the interchangeable lens from the image shift amount.

  In the focus detection apparatus of the eighth embodiment, since the offset amount is actually measured, the image shift amount calculated in the focus detection area is calculated even if there is an individual difference in the aberration characteristics of the imaging optical system of the interchangeable lens. The defocus amount between the best image plane of the interchangeable lens and the planned focal plane can be accurately detected by accurately correcting the aberration characteristics of the interchangeable lens according to individual differences.

  When it is difficult to actually measure the offset amount in all combinations of the aperture F value, the focus lens position, and the zoom lens position, in combination with the fourth embodiment, the representative aperture F value, the focus lens position, and the zoom lens position The offset amount may be actually measured in the combination, and the offset amount obtained by calculation from the optical design information in the fourth embodiment may be calibrated based on the actually measured value.

<Ninth Embodiment>
In the ninth embodiment, offset amounts corresponding to all the interchangeable lenses are stored in advance as a table on the camera body side, and lens information such as lens type, aperture F value, focus lens position, zoom from the interchangeable lens to the camera body is stored. This is an embodiment of the present invention in which the lens position is sent and the image displacement amount calculated based on the focus detection pixel data is corrected on the camera body side by the offset amount corresponding to the lens information received from the interchangeable lens.

  FIG. 23 is a block diagram showing processing portions related to calculation and use of the offset amount in the above-described ninth embodiment of the present invention.

  In the upper diagram of FIG. 23, in the first step, that is, the manufacturing stage, the offset amount table is written in the camera body from the offset amount table generating device. The offset table generation device stores in advance optical design information for all interchangeable lenses and optical design information for a focus detection optical system (such as a microlens). The offset amount table generation device selects one interchangeable lens, and based on the optical design information of the interchangeable lens and the optical design information of the focus detection optical system, according to the combination of the aperture F value, the focus lens position, and the zoom lens position, A pair of point image distribution data in the arrangement direction of the focus detection pixels in a state where the best image plane and the planned focal plane coincide with each other is calculated. Next, the same image shift detection calculation processing as the image shift detection calculation processing performed on the focus detection pixel data in the camera body is performed on the calculated pair of point image distribution data, and the offset amount corresponding to the pair of point image distribution data is calculated. To do.

  The above calculation process is performed by sequentially changing the combination of the aperture F value, the focus lens position, the zoom lens position, and the type of the interchangeable lens, and the calculated offset amount and the corresponding aperture F value, the focus lens position, the zoom lens position. And the lens type information are combined to create an offset amount table. The offset amount table finally generated on the offset amount table generating device side is sent to the camera body side and stored as the offset amount table.

  23, the interchangeable lens is attached to the camera body in the second step, that is, in the use stage. The interchangeable lens side sends the set aperture F value, focus lens position, zoom lens position information and interchangeable lens type information to the camera body. Based on the received aperture F value, focus lens position, zoom lens position information, and interchangeable lens type information, the camera body selects an offset amount according to the state of the photographing optical system at that time from the offset amount table. In the camera body, a predetermined image shift detection calculation (formulas (1) to (5)) is performed on the focus detection pixel data to calculate an image shift amount. Then, the image shift amount is corrected by subtracting the selected offset amount from the image shift amount.

  In the focus detection apparatus of the ninth embodiment, the image shift amount calculated based on the focus detection pixel data in the focus detection area is accurately corrected according to the aberration characteristics of the interchangeable lens, and the best image plane of the interchangeable lens is scheduled. The defocus amount between the focal planes can be accurately detected.

  In the first to ninth embodiments described above, the offset amount is calculated based on a pair of point image distribution data. However, a general image distribution is a point in the image distribution when there is no aberration. Since the image distribution is convoluted, the offset amount may be calculated based on image distribution data other than the point image, for example, image distribution data such as an edge image and a line image as shown in FIG. .

  In the focus detection devices according to the first to ninth embodiments described above, the image sensor 212 is a photoelectric conversion device including the image pickup pixel 310 and the focus detection pixels 315 and 316. However, the focus detection device according to the present invention may include a focus detection-dedicated photoelectric conversion device having only focus detection pixels such as the focus detection pixels 315 and 316.

<Others>
The imaging apparatus to which the focus detection apparatus according to the present invention is applied is not limited to a digital camera having a configuration in which an interchangeable lens is attached to the camera body as described above. For example, the present invention can be applied to a lens-integrated digital camera or video camera. Furthermore, the present invention can be applied to a small camera module built in a mobile phone, a surveillance camera, a visual recognition device for a robot, an in-vehicle camera, and the like.

10 microlens, 11, 15, 16 photoelectric conversion unit,
41, 42 upper part, 43, 44 lower part, 45, 46, 47, 48 edge part,
51, 55, 56 Point image distribution, 65, 66, 67, 68 Subject image,
71, 75, 76 luminous flux, 90 exit pupil, 91 optical axis,
95,96 Distance pupil, 97 area, 98 planned focal plane, 99 plane,
100 shooting screen, 101, 102 focus detection area,
201 digital camera, 202 interchangeable lens, 203 camera body,
204 mount unit, 206 lens control device,
208 zooming lens, 209 lens, 210 focusing lens,
211 Aperture, 212 Image sensor, 213 Electrical contact,
214 body control device,
215 liquid crystal display element driving circuit, 216 liquid crystal display element, 217 eyepiece,
219 memory card, 221 AD converter,
310 Imaging pixels, 315, 316 Focus detection pixels

Claims (10)

A photoelectric conversion device that generates, by photoelectric conversion, a pair of image signals corresponding to a pair of images formed on a planned focal plane by a pair of light beams that pass through a pair of regions of the exit pupil of the imaging optical system;
An image shift amount detection means for detecting a relative image shift amount of the pair of images based on a correlation between the pair of image signals;
An image shift amount correction means for calculating a corrected image shift amount based on the relative image shift amount and a predetermined offset amount;
Defocus amount calculation means for calculating a defocus amount by multiplying the correction image shift amount by a predetermined conversion coefficient;
Offset amount acquisition for acquiring the predetermined offset amount determined according to a difference in shape of a pair of images caused by a pair of light beams passing through a pair of exit pupil areas of the imaging optical system due to aberrations of the imaging optical system A focus detection device. The focus detection apparatus according to claim 1,
The predetermined offset amount acquired by the offset amount acquisition means is a value of a pair of image signals corresponding to the pair of images when the pair of images having the difference in shape is a predetermined optimal image. A focus detection apparatus characterized by a relative image shift amount of the pair of images determined according to the difference in shape based on the degree of correlation. The focus detection apparatus according to claim 2,
The offset amount acquisition means includes
Image signal acquisition means for acquiring a pair of image signals corresponding to the pair of images when the pair of images having the shape difference is the predetermined optimum image;
An offset for calculating, as the predetermined offset amount, a relative image shift amount of the pair of images determined according to the difference in shape based on the correlation between the pair of image signals acquired by the image signal acquisition unit. A focus detection apparatus comprising: a quantity calculation unit; The focus detection apparatus according to claim 2 or 3,
The predetermined optimum image is predetermined according to optical design information of the photographing optical system,
The focus detection apparatus characterized in that the offset amount acquisition means acquires the relative image shift amount associated with the optical design information of the photographing optical system as the predetermined offset amount. The focus detection apparatus according to any one of claims 2 to 4,
The predetermined optimal image is predetermined according to a formation position and a formation direction of the pair of images having the shape difference with respect to the optical axis of the photographing optical system,
The focus detection apparatus, wherein the offset amount acquisition unit acquires the relative image shift amount associated with the formation position and the formation direction as the predetermined offset amount. The focus detection apparatus according to any one of claims 2 to 5,
The predetermined optimal image is predetermined according to optical design information of a focus detection optical system that causes the photoelectric conversion device to receive the pair of light beams forming the pair of images having the difference in shape,
The focus detection apparatus, wherein the offset amount acquisition unit acquires the relative image shift amount corresponding to the optical design information of the focus detection optical system as the predetermined offset amount. The focus detection apparatus according to any one of claims 2 to 6,
The degree of correlation of the pair of image signals corresponding to the pair of images having the difference in shape changes according to the type of correlation calculation processing of the pair of image signals,
The focus detection apparatus, wherein the offset amount acquisition unit acquires the relative image shift amount based on the correlation corresponding to the type of the correlation calculation processing as the predetermined offset amount. The focus detection apparatus according to any one of claims 2 to 7,
The predetermined optimal image is obtained when the resolution of the pair of images is maximized with respect to a change in the image position of the pair of images having the difference in shape on the optical axis of the photographing optical system. Any one of the image position, the image position when the size of the pair of images is minimized, and the image position when the MTF of a predetermined spatial frequency included in the pair of image signals is maximized. A focus detection device characterized by that. The focus detection apparatus according to any one of claims 2 to 8,
Further comprising optical design information acquisition means for acquiring optical design information of the photographing optical system;
The predetermined optimum image is predetermined according to optical design information of the photographing optical system,
The focus detection apparatus, wherein the offset amount acquisition unit acquires the predetermined offset amount based on the optical design information of the photographing optical system acquired by the optical design information acquisition unit. The focus detection apparatus according to any one of claims 1 to 9,
The focus detection apparatus characterized in that the pair of images having the difference in shape when the predetermined offset amount is determined are a pair of point images.

Images