Imaging device

Abstract

To obtain a satisfactory result of focus detection even when focus detection is performed through an optical system with a large aberration.SOLUTION: An imaging apparatus has: image pick-up device 107 having a pair of focus detection pixels 201, 202 that receive light beams having passed through areas different from each other in an exit pupil of an imaging optical system; and focus detection means 121 that detects the focus of the imaging optical system by using a pair of focus detection signals generated by using output signals from the pair of focus detection pixels. The focus detection means can perform focus detection in a plurality of spatial frequency bands, and obtains a result of focus detection to be used in a spatial frequency band according to the amount of aberration of the imaging optical system of the plurality of spatial frequency bands.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an imaging device.

Background Art

[0002] As an autofocus detection (AF) method of an imaging device, a phase difference focus detection method (phase difference AF) is known. Phase difference AF is an AF often used in digital still cameras, and there are some in which an imaging element is used as a focus detection sensor. For example, Patent Document 1 discloses a method of reducing the influence of noise by performing pupil division type focus detection and distance measurement in a plurality of spatial frequency bands.

[0003] Since phase difference AF performs focus detection using an optical image, the aberration of the optical system that forms the optical image may give an error to the focus detection result. Patent Document 2 discloses a method of correcting a focus detection error caused by the shapes of a pair of optical images formed by a pair of focus detection light beams not matching due to the aberration of the optical system in the in-focus state.

[0004] Also, as a method of switching the degree of soft focus of a lens, Patent Document 3 discloses a method of storing images with a plurality of focus degrees and obtaining an image with a desired degree of soft focus by image processing. Further, as a method of acquiring images under a plurality of imaging conditions, Patent Document 4 discloses a camera capable of setting the number of imaging times under a plurality of types of imaging conditions and performing bracketing imaging.

[0005] Furthermore, as a method of obtaining better focus detection accuracy, Patent Document 5 discloses a method of correcting a focus detection error by multiplying a correction coefficient by a focus detection amount.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

[0007] However, in phase-detection autofocus, it can be difficult to correct focus detection errors caused by aberrations. For example, when using lenses that intentionally produce large aberrations, known as soft-focus lenses, the focus detection error is large and changes depending on the amount of blur, making correction difficult.

[0008] Furthermore, the method disclosed in Patent Document 3 obtains an image with the desired degree of soft focus by image synthesis, and therefore cannot reproduce the blur caused by the distance to the subject, as is the case with images obtained using an actual soft focus lens, making it difficult to obtain a natural soft focus image. In addition, obtaining an image with the desired degree of soft focus requires imaging and image processing at multiple degrees of focus, resulting in a heavy processing load.

[0009] Furthermore, while Patent Document 4 discloses that a user can select a desired image from multiple images obtained by bracket imaging, it does not describe how to change the degree of soft focus.

[0010] Furthermore, Patent Document 5 does not describe a method for correcting the amount of defocus obtained by focus detection when the amount of aberration in the optical system is large or when the amount of aberration is variable.

[0011] The present invention provides an imaging device, etc., that can obtain good focus detection results even when performing focus detection through an optical system with large aberrations. Furthermore, the present invention provides an imaging device, etc., that can generate images with a soft focus degree desired by the user. [Means for solving the problem]

[0012] An imaging device as one aspect of the present invention includes an image sensor including a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of an imaging optical system, and a focus detection means that performs focus detection of the imaging optical system using a pair of focus detection signals generated using the output signals from the pair of focus detection pixels. The focus detection means is capable of performing focus detection in multiple spatial frequency bands, and among the multiple spatial frequency bands, the imaging optical system spherical surface Depending on the amount of aberration They are different This method is characterized by obtaining the focus detection result to be used within the spatial frequency band.

[0013] Furthermore, as another aspect of the present invention, a lens device is detachably attached to the above imaging device and has an imaging optical system. The lens device has an imaging optical system spherical surface Information regarding aberrations or spherical surface Depending on the amount of aberration They are different A storage means for storing information regarding a spatial frequency band for focus detection, and Regarding spatial frequency bands for focus detection It is characterized by having a notification means for notifying the imaging device of information.

[0014] Furthermore, the lens device, as another aspect of the present invention, the above An operating member that can be attached to an imaging device and accepts user operation, and in response to the operation of the operating member spherical surface It comprises an optical element that changes aberrations and a communication control means that communicates with an imaging device. The communication control means is spherical surface Information indicating that the imaging device has an optical element that changes aberrations is transmitted, and when the operating member is operated by the user, the changes are transmitted in accordance with the operation. spherical surface It is characterized by transmitting information corresponding to the amount of aberration.

[0015] Another aspect of the control method of the present invention is applied to an imaging device having an imaging element including a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system. The control method includes a step of generating a pair of focus detection signals using output signals from the pair of focus detection pixels, and among a plurality of spatial frequency bands in which focus detection of the imaging optical system is possible using the pair of focus detection signals, according to the spherical surface aberration amount They are different a step of obtaining a focus detection result to be used in a spatial frequency band. It should be noted that a computer program that causes a computer of the imaging device to execute the processing according to this control method also constitutes another aspect of the present invention.

[0016] Furthermore, another aspect of the control method of the present invention is applied to a lens device that is detachably attached to the imaging device having the above control method and has an imaging optical system. The control method includes a step of storing information regarding the spherical surface aberration amount or spherical surface information regarding the spatial frequency band for focus detection according to the They are different aberration amount, and a step of notifying the imaging device of the Regarding spatial frequency bands for focus detection information. [[ID=1十八]]

[0017] Another aspect of the control method of the present invention is applied to a lens device that is attachable to an imaging device and has an optical member that changes aberrations in response to an operation by a user on an operation member. The control method includes a step of transmitting information indicating that the lens device has an optical member that changes aberrations to the imaging device, and a step of transmitting information corresponding to the spherical surface aberration amount that changes in response to the operation when the operation member is operated by the user. It should be noted that a computer program that causes a computer of the lens device to execute the processing according to each of the above control methods also constitutes another aspect of the present invention. spherical surface aberration amount that changes in response to the operation when the operation member is operated by the user. It should be noted that a computer program that causes a computer of the lens device to execute the processing according to each of the above control methods also constitutes another aspect of the present invention. spherical surface aberration amount that changes in response to the operation when the operation member is operated by the user. It should be noted that a computer program that causes a computer of the lens device to execute the processing according to each of the above control methods also constitutes another aspect of the present invention.

[0018] Furthermore, another aspect of the present invention is an imaging device which includes an image sensor that receives a light beam from an imaging optical system to perform imaging and a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system, and a focus detection means that performs focus detection of the imaging optical system using a pair of focus detection signals generated using the output signals from the pair of focus detection pixels. The imaging optical system is an optical system in which the amount of aberration can be changed, and is characterized by having a control means that performs focus control of the imaging optical system and imaging according to the focus detection result each time the amount of aberration is changed.

[0019] Furthermore, another aspect of the present invention is an imaging device comprising: an image sensor including a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system; a focus detection means that performs focus detection of the imaging optical system using a pair of focus detection signals generated using the output signals from the pair of focus detection pixels; and a control means that acquires correction information according to the amount of aberration of the imaging optical system and corrects the focus detection result using the correction information.

[0020] Furthermore, another aspect of the present invention, the control method, is applied to an imaging device having an image sensor that receives a light beam from an imaging optical system to perform imaging and includes a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system. The imaging optical system is an optical system in which the amount of aberration can be changed. The control method is characterized by comprising the steps of: detecting the focus of the imaging optical system using a pair of focus detection signals generated using the output signals from the pair of focus detection pixels; and controlling the focus of the imaging optical system and performing imaging according to the focus detection result each time the amount of aberration is changed.

[0021] Furthermore, another aspect of the present invention, the control method, is applied to an imaging device having an image sensor that includes a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system. The control method is characterized by comprising the steps of: detecting the focus of the imaging optical system using a pair of focus detection signals generated using the output signals from the pair of focus detection pixels; and acquiring correction information according to the amount of aberration of the imaging optical system and correcting the focus detection result using the correction information. A computer program that causes the computer of the imaging device to execute the processing according to each of the above control methods also constitutes another aspect of the present invention. [Effects of the Invention]

[0022] According to the present invention, Depending on the amount of spherical aberration in the imaging optical system Good focus detection results can be obtained. 。 [Brief explanation of the drawing]

[0023] [Figure 1] A block diagram showing the configuration of an imaging device according to Embodiment 1 of the present invention. [Figure 2] A diagram showing the pixel arrangement of the image sensor in Example 1. [Figure 3] Plan view and cross-sectional view of a pixel in Example 1. [Figure 4] A diagram illustrating the pixels and pupil division in Example 1. [Figure 5] A diagram illustrating the image sensor and pupil division in Example 1. [Figure 6] This figure shows the relationship between the defocus amount and image shift amount of the first focus detection signal and the second focus detection signal in Example 1. [Figure 7] A flowchart showing the focus detection process and imaging process in Example 1. [Figure 8] A diagram showing the spatial frequency band of focus detection in Example 1. [Figure 9] A diagram showing the defocus curve in a typical imaging optical system. [Figure 10] A diagram showing the defocus curve in an imaging optical system with large aberrations. [Figure 11] A flowchart illustrating the bandwidth selection process in Example 1. [Figure 12] A figure showing a comparative example of LSF in Example 1. [Figure 13] A flowchart illustrating the process in Example 3. [Figure 14] A diagram showing the soft-focus lens in Example 3. [Figure 15] This figure shows an image captured using the aberration bracketing function in Example 3. [Figure 16] A diagram showing the configuration of the imaging device in Example 3. [Figure 17] A flowchart illustrating the focus detection process in Example 4. [Figure 18] A flowchart showing the correction coefficient calculation process in Example 4. [Figure 19] A figure showing the correction coefficient in Example 4. [Modes for carrying out the invention]

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Examples]

[0025] Figure 1 shows the configuration of an imaging device (hereinafter referred to as "camera") which is Embodiment 1 of the present invention. The camera has an imaging optical system including a first lens group 101, an aperture shutter 102, a second lens group 103, and a third lens group 105, arranged in order from the object (subject) side. The imaging optical system may be provided integrally with the camera body having an image sensor, which will be described later, or it may be provided in a lens device (interchangeable lens) that is detachably attached to the camera body.

[0026] The first lens group 101 moves in the direction of the optical axis, which is the direction in which the optical axis of the imaging optical system extends, for zooming. The aperture shutter 102 has an aperture function to adjust the amount of light by changing its aperture diameter and a shutter function to control the exposure time when capturing still images. The second lens group 103 moves in the direction of the optical axis together with the aperture shutter 102 during zooming. The third lens group 105 moves in the direction of the optical axis for focusing. The optical low-pass filter 106 is an optical element for reducing false colors and moiré. The image sensor 107 consists of a two-dimensional CMOS sensor and peripheral circuits and is located on the imaging plane of the imaging optical system.

[0027] The zoom actuator 111 drives the first lens group 101 and the second lens group 103 in the optical axis direction by rotating a cam cylinder (not shown) around the optical axis when changing magnification. The aperture shutter actuator 112 drives the aperture shutter 102. The focus actuator 114 drives the third lens group 105 in the optical axis direction when focusing.

[0028] The electronic flash 115 emits light to illuminate the subject. The AF light-emitting unit 119 projects AF assist light onto the subject, forming an image of a mask with a predetermined aperture pattern, in order to improve the focus detection capability for dark or low-contrast subjects in AF (autofocus).

[0029] The camera CPU 121 is a computer that controls the entire camera, controlling the operation of various circuits in the camera according to the program, and controlling the operation of AF, imaging, image processing, and recording. The camera CPU 121 also stores correction value calculation coefficients required for AF using the output signal from the image sensor 107 in its internal memory. Multiple correction value calculation coefficients are available, corresponding to the focus state corresponding to the position of the third lens group 105, the zoom state corresponding to the positions of the first lens group 101 and the second lens group 103, the aperture value (F number) of the imaging optical system, and the set pupil distance and pixel size of the image sensor 107. When performing AF, the camera CPU 121 calculates a correction value from the correction value calculation coefficient corresponding to the combination of focus state, zoom state, F number, set pupil distance and pixel size, and the image height on the image sensor 107.

[0030] Furthermore, if the imaging optical system is provided in the interchangeable lens, a memory for storing the correction value calculation coefficient may be provided within the interchangeable lens, and the camera body may calculate the correction value using the correction value calculation coefficient obtained from the interchangeable lens via communication during autofocus.

[0031] The electronic flash control circuit 122 controls the emission of the electronic flash 115 in synchronization with the imaging operation. The auxiliary light drive circuit 123 controls the emission of the AF light-emitting unit 116 in synchronization with the focus detection operation for AF. The image sensor drive circuit 124 controls the imaging (photoelectric conversion) operation of the image sensor 107 and also performs A / D conversion on the output signal from the image sensor 107 and sends it to the camera CPU 121. The image processing circuit 125 performs image processing such as gamma conversion and color interpolation on the A / D converted output signal (imaging signal described later) to generate image data, and also performs compression processing such as JPEG compression on the image data.

[0032] The focus drive circuit 126 drives the third lens group 105 by controlling the focus actuator 114 based on a focus command from the camera CPU 121 corresponding to the focus detection result. The aperture shutter drive circuit 128 drives the aperture shutter 102 by controlling the aperture shutter actuator 112 based on an aperture shutter command from the camera CPU 121 that has performed photometry using the imaging signal. The zoom drive circuit 129 drives the first and second lens groups 101 and 103 by controlling the zoom actuator 111 based on a zoom command from the camera CPU 121 that has detected the user's zoom operation.

[0033] The display unit 131 consists of a display device such as an LCD and displays various information such as the camera's imaging mode, a preview image before imaging, a recording image after imaging, the focus detection area (AF frame), and the focus status. The operation switch group 132 includes a power switch, a release (imaging trigger) switch, a zoom operation switch, an imaging mode selection switch, etc. The flash memory 133 is detachable from the camera and records the images for recording.

[0034] Figure 2 shows a partial pixel arrangement of the image sensor 107. The image sensor 107 has multiple imaging pixels 200. Figure 2 shows a 4x4 arrangement of imaging pixels 200. The 2x2 arrangement of imaging pixels 200 includes an imaging pixel 200R located in the upper left with R (red) spectral sensitivity, an imaging pixel 200G located in the upper right and lower left with G (green) spectral sensitivity, and an imaging pixel 200B located in the lower right with B (blue) spectral sensitivity. Each imaging pixel 200 is composed of a first focus detection pixel 201 and a second focus detection pixel 202, which are a pair of focus detection pixels divided in the x direction. The image sensor 107 enables the acquisition of imaging signals and focus detection signals by arranging a large number of 4x4 imaging pixels (8x4 focus detection pixels) as shown in Figure 2 on the imaging surface (light-receiving surface).

[0035] The camera CPU 121, acting as both a focus detection and control means, uses the focus detection signal from the image sensor 107 to detect the focus of the imaging optical system. The camera CPU 121 then performs focus control, controlling the drive of the third lens group 105 based on the defocus amount, which is the focus detection result. In this way, image plane phase-detection autofocus is performed.

[0036] Figure 3(a) shows one imaging pixel 200G as viewed from the light-receiving side (+z side) of the image sensor 107, and Figure 3(b) shows the pixel structure in the aa cross section of Figure 3(a) as viewed from the -y side.

[0037] As shown in Figure 3(b), the imaging pixel 200G is N in the x direction. H It has divided (two-part) photoelectric conversion units 301 and 302, and these photoelectric conversion units 301 and 302 constitute the first and second focus detection pixels 201 and 202 shown in Figure 2, respectively. The photoelectric conversion units 301 and 302 are N in the y direction V They may be divided. Microlenses 305 are formed in the imaging pixel 200G to focus the light incident on the photoelectric conversion units 301 and 302. The photoelectric conversion units 301 and 302 may be pin-structured photodiodes with an intrinsic layer sandwiched between a p-type layer and an n-type layer, or they may be pn-junction photodiodes by omitting the intrinsic layer.

[0038] A color filter 306 for green (G) is formed between the microlens 305 and the photoelectric conversion units 301 and 302. Color filters for red (R) and blue (B) are formed in the imaging pixels 200R and 200B, respectively. Color filters other than RGB may be provided, or color filters may be omitted.

[0039] Light incident on the imaging pixel 200G is focused by the microlens 305, spectrally separated by the color filter 306, and then received by the photoelectric conversion units 301 and 302. In the photoelectric conversion units 301 and 302, electron-hole pairs are generated according to the amount of light received. After these are separated in the depletion layer, the negatively charged electrons are accumulated in the n-type layer. Meanwhile, the holes are discharged to the outside of the image sensor 107 through a p-type layer connected to a constant voltage source (not shown). The electrons accumulated in the n-type layers of the photoelectric conversion units 301 and 302 are transferred to the capacitance unit (FD) via a transfer gate and converted into a voltage signal.

[0040] Figure 4 shows the relationship between the pixel structure shown in Figure 3(b) and the division of the exit pupil of the imaging optical system (pupil division). In Figure 4, the x and y axes of the pixel structure are inverted compared to Figure 3(b) in order to correspond with the coordinate axes of the pixel structure and the exit pupil surface.

[0041] The first partial pupil region 501 is the region through which light received by the photoelectric conversion unit 301 (first focus detection pixel 201) passes within the exit pupil region 500, and is generally conjugate to the photo-receiving surface of the photoelectric conversion unit 301, whose centroid is eccentric in the -x direction, and the microlens 305. The centroid of the first pupil region 501 is eccentric to the +X side on the exit pupil surface. The second partial pupil region 502 is the region through which light received by the photoelectric conversion unit 302 (second focus detection pixel 202) passes within the exit pupil region 500, and is generally conjugate to the photo-receiving surface of the photoelectric conversion unit 302, whose centroid is eccentric in the +x direction, and the microlens 305. The centroid of the second pupil region 502 is eccentric to the -X side on the exit pupil surface. The exit pupil region 500 allows light that has passed through it to be received by the entire imaging pixel 200G, which is composed of photoelectric conversion units 301 and 302.

[0042] In image-plane phase-detection autofocus, pupil division is performed using microlenses 305 provided for each image pixel on the image sensor 107, and is therefore affected by diffraction. In Figure 4, the distance from the light-receiving surface of each photoelectric conversion unit to the exit pupil surface (pupil distance) is several tens of millimeters, while the diameter of the microlens 305 is several micrometers. As a result, the aperture value of the microlens 305 becomes tens of thousands, causing diffraction blur on the level of several tens of millimeters. Consequently, the optical image formed on the light-receiving surface of the photoelectric conversion unit does not become a clear image of the exit pupil region or partial pupil region, but rather an image with an intensity distribution corresponding to the light-receiving rate according to the angle of incidence.

[0043] Figure 5 shows the incident light beam to the image sensor 107 during pupil division. The light beams that have passed through the first partial pupil region 501 and the second partial pupil region 502 are incident on the corresponding photoelectric conversion units 301 and 302 in the image sensor 107 at different angles to each other.

[0044] The image sensor 107 of this embodiment has a first focus detection pixel 201 (photoelectric conversion unit 301) that receives a light beam that has passed through the first partial pupil region 501 of the imaging optical system, and a second focus detection pixel 202 (photoelectric conversion unit 302) that receives a light beam that has passed through the second partial pupil region 502. Furthermore, it has an imaging pixel 200 that receives a light beam that has passed through the exit pupil region 500, which is a combination of the first partial pupil region 501 and the second partial pupil region 502. In this embodiment, each imaging pixel is composed of first and second focus detection pixels 201 and 202, but the imaging pixel and the first and second focus detection pixels may be provided as separate pixels.

[0045] In this embodiment, a first focus detection signal is generated by collecting the output signals from the first focus detection pixels 201 of multiple imaging pixels 200, and a second focus detection signal is generated by collecting the output signals from the second focus detection pixels 202 of multiple imaging pixels 200. The camera CPU 121 uses these pairs of first and second focus detection signals to perform focus detection in image plane phase-detection AF. Furthermore, by adding the output signals from the first and second focus detection pixels 201 and 202 for each imaging pixel 200, an imaging signal with a resolution of effective pixels N is generated.

[0046] Next, using Figure 6, we will explain the relationship between the phase difference (image shift amount) of the first and second focus detection signals and the amount of defocus of the subject image. In the figure, the light beam that has passed from the subject planes 801 and 802 through the first and second partial pupil regions 501 and 502 of the imaging optical system reaches the imaging surface 800 of the image sensor 107.

[0047] The defocus amount d is the distance from the image formation position of the subject image to the image sensor 800. A negative defocus amount (d<0) represents a front-focus state where the image formation position is on the subject side of the image sensor 800, and a positive defocus amount (d>0) represents a back-focus state where the image formation position is on the opposite side of the image sensor 800 from the subject side. In a focused state where the image formation position is on the image sensor 800, d=0. The figure shows a focused state with respect to the subject surface 801 and a front-focus state with respect to the subject surface 802. In the following explanation, the front-focus state (d<0) and the back-focus state (d>0) are collectively referred to as a defocus state (|d|>0).

[0048] In the front-focused state, the light beam from the subject surface 802 that passes through the first and second partial pupil regions 501 and 502 is first focused and then spreads out with widths Γ1 and Γ2 centered on the centroid positions G1 and G2, respectively, forming a blurred image on the image sensor 800. The blurred image is received by the first and second focus detection pixels 201 and 202 on the image sensor 107, thereby generating the first and second focus detection signals. The first and second focus detection signals represent the blurred image of the subject surface 802 that has spread out with blur widths Γ1 and Γ2 centered on the centroid positions G1 and G2 on the image sensor 800. The blur widths Γ1 and Γ2 increase approximately proportionally with the increase in the magnitude |d| of the defocus amount d. Furthermore, the magnitude of the image displacement p (difference between centroid positions G1 and G2) of the first and second focus detection signals, |p|, also increases almost proportionally with the increase in |d|. The same applies to the back-focused state, although the direction of image displacement of the first and second focus detection signals is opposite to that of the front-focused state.

[0049] Therefore, the amount of defocus d can be calculated using the amount of image displacement p and a predetermined conversion factor K for converting the amount of image displacement p into a defocus amount d.

[0050] The flowchart in Figure 7 illustrates the focus detection process in this embodiment. The camera CPU 121 executes this process according to the computer program. Here, the Y signal obtained by adding the first and second focus detection signals of four imaging pixels, G, R, B, and G, is used as the first and second focus detection signals.

[0051] In step S10, the camera CPU 121 generates a first focus detection signal (image A) from the output signal from the first focus detection pixel within the focus detection region on the image sensor 107, and generates a second focus detection signal (image B) from the output signal from the second focus detection pixel within the same focus detection region.

[0052] Next, in step S20, the camera CPU 121 performs column-direction addition on the first and second focus detection signals to reduce the amount of signal data. Furthermore, it performs addition on the G, R, B, G focus detection signals to generate the Y signal. These two addition processes together are called pixel addition. When there are two pixels to add, the pixel pitch doubles, so the Nyquist frequency becomes half of the non-additional frequency. When there are three pixels to add, the pixel pitch triples, so the Nyquist frequency becomes one-third of the non-additional frequency.

[0053] Next, in step S30, the camera CPU 121 performs shading correction processing (optical correction processing) on ​​the first and second focus detection signals to equalize their intensities.

[0054] Next, in step S40, the camera CPU 121 performs bandpass filtering on the first and second focus detection signals in a specific passband frequency band to improve their correlation (signal matching) and thus improve focus detection accuracy. Examples of bandpass filtering include difference-type filtering such as {1, 4, 4, 4, 0, -4, -4, -4, -1} which cuts out DC components and extracts edges, and additive-type filtering such as {1, 2, 1} which suppresses high-frequency noise components.

[0055] Next, in step S50, the camera CPU 121 performs a shift process to relatively shift the first and second focus detection signals, after bandpass filtering, in the pupil division direction, and calculates a correlation amount that represents the degree of agreement between these first and second focus detection signals.

[0056] Let A(k) be the k-th first focus detection signal after bandpass filtering, B(k) be the second focus detection signal, and W be the range of number k corresponding to the focus detection region. If s is the amount of shift due to the shifting process, and Γ is the shift range of the shift amount s, then the correlation quantity COR is calculated by equation (1).

[0057]

number

[0058] The shift process of the shift amount s generates a shift-subtracted signal by matching the k-th first focus detection signal A(k) with the ks-th second focus detection signal B(ks) and subtracting them. The absolute value of the generated shift-subtracted signal is calculated, and the correlation amount COR(s) is calculated by summing the values ​​of the indices k within the range W corresponding to the focus detection region. If necessary, the correlation amounts calculated for each row may be added together for each shift amount across multiple rows.

[0059] Next, in step S60, the camera CPU 121 calculates a real-valued shift amount s that minimizes the correlation amount COR(s) through sub-pixel calculations, and defines this as the image displacement amount p. Furthermore, the camera CPU 121 calculates the defocus amount (Def) d by multiplying the image displacement amount p by a conversion coefficient K. In this way, the defocus amount is detected.

[0060] In this example, the amount of defocus is detected in multiple (in this case, three) spatial frequency bands with different levels. The spatial frequency band is determined by the number of pixels added in step S20 and the bandpass filtering in step S40. The higher the number of pixels added and the lower the transmission bandwidth of the bandpass filtering, the lower the spatial frequency band used to detect the amount of defocus. Figure 8 shows the spatial frequency bands for levels 1, 2, and 3. Level 1 has the highest spatial frequency band, and level 3 has the lowest spatial frequency band.

[0061] Note that the number of spatial frequency bands is not limited to three; other numbers are also acceptable. Furthermore, it is not necessary to simultaneously detect the amount of defocus in multiple spatial frequency bands.

[0062] The focus detection accuracy in phase-detection autofocus is represented as a defocus curve. Figure 9 shows an example of a typical defocus curve based on optical calculation results. The solid, dashed, and thin dashed lines show the detection results of the amount of defocus in the spatial frequency bands of levels 1, 2, and 3 mentioned above. The horizontal axis shows the correct amount of defocus, and the vertical axis shows the detected amount of defocus. The ideal state, where the detection error is 0, is when the values ​​on the horizontal axis and the vertical axis are always equal (a straight line making a 45° angle with respect to the horizontal and vertical axes).

[0063] In Figure 9, in the region where the amount of defocus is large, there are differences in the results of the defocus amount across the three spatial frequency bands, but they roughly coincide with a 45° straight line. Furthermore, near the in-focus state where the amount of defocus is 0, the detection error is small in the detection results of the defocus amount across all spatial frequency bands from level 1 to 3. Generally, to suppress variations in detection results caused by noise, the detection result of the defocus amount in the highest possible spatial frequency band is used for the final focus determination.

[0064] Figure 10 shows an example of a defocus curve obtained from optical calculations in an imaging optical system with a large spherical aberration, one of the various aberrations. The defocus curve in the highest spatial frequency band (level 1) deviates significantly from a 45° straight line, indicating a large detection error. Furthermore, the curved shape of the defocus curve indicates that the detection error changes depending on the amount of defocus. As the spatial frequency band decreases (levels 2 and 3), the defocus curve approaches a straight line, indicating a smaller detection error.

[0065] Generally, images formed by imaging optical systems with large spherical aberrations are blurred even near the point of focus, and the increase in blurring is small even when the amount of defocus is increased. When the spatial frequency bandwidth is high, the edges of line images, which change little due to defocus, are detected, and when the spatial frequency bandwidth is low, changes in the entire image are detected. For this reason, imaging optical systems with large spherical aberrations yield better defocus detection results when the spatial frequency bandwidth is low.

[0066] Figure 12 shows the LSF (line image) in this embodiment. The first focus detection signal is shown as LSF_A, and the second focus detection signal as LSF_B. Def0 indicates the in-focus state, while Def- and Def+ indicate states where the front-focused and back-focused sides are blurred by the same amount, respectively. In an imaging optical system with small aberrations as shown in Figure 9, LSF_A and LSF_B almost coincide in the in-focus state. Also, in Def- and Def+, the positions of LSF_A and LSF_B are swapped, but the spacing is almost the same. Note that when LSF_A and LSF_B are added together, it becomes the LSF of the imaging signal.

[0067] On the other hand, as shown in Figure 10, in imaging optical systems with large aberrations, the distortion and asymmetry of LSF_A and LSF_B are significant, and even in the focused state, the shapes of LSF_A and LSF_B do not match, resulting in a large detection error. In Def-, the spacing between LSF_A and LSF_B is correct when the aberration is small, but when the aberration is large, the spacing between LSF_A and LSF_B becomes smaller than the correct spacing. Also, in Def+, the spacing between LSF_A and LSF_B is correct when the aberration is small, but when the aberration is large, the spacing between LSF_A and LSF_B becomes larger than the correct spacing.

[0068] As mentioned above, when aberrations are large, the LSF collapse and asymmetry cause the detection error to increase in the high-frequency band where edges are detected, and the amount of detection error changes depending on the amount of defocus.

[0069] In this embodiment, in order to obtain good focus detection accuracy even in imaging optical systems with large aberrations, the amount of defocus detected in a spatial frequency band corresponding to the information regarding the amount of aberration of the imaging optical system is used from among multiple spatial frequency bands.

[0070] The following describes a case where an imaging optical system is provided in an interchangeable lens, and the interchangeable lens is a soft-focus lens in which the amount of spherical aberration of the imaging optical system can be changed (variable setting). In this case, the interchangeable lens has a lens CPU 151, shown in parentheses in Figure 1. The lens CPU 151, which is a computer, can communicate with the camera CPU 121 and controls the focus drive circuit 126, aperture drive circuit 128, and zoom drive circuit 129 provided in the interchangeable lens in response to commands from the camera CPU 121. Similarly, the lens memory 152, shown in parentheses in Figure 1, which is a storage means, stores various lens information such as the amount of spherical aberration of the variable-setting imaging optical system. In addition, the lens CPU 151, which is a notification means, can notify the camera body (camera CPU 121) of information regarding the variable-setting amount of spherical aberration via communication.

[0071] The flowchart in Figure 11 shows the bandwidth selection process (control method) that the camera CPU 121 executes according to the computer program. In step S110, the lens CPU 151 transmits (notifies) information regarding the amount of aberration of the imaging optical system (hereinafter referred to as aberration amount information) to the camera, and in step S120, the camera CPU 121 receives the aberration amount information.

[0072] Aberration information may be information indicating the actual amount of aberration, or an index indicating the magnitude of the aberration. It may also be information indicating the magnitude of wavefront aberration, or information indicating the magnitude of the aberration as binary values. Furthermore, if the camera CPU 121 recognizes that the interchangeable lens is a soft-focus lens from identification information such as the lens ID, the aberration setting value of the soft-focus lens may be obtained as aberration information.

[0073] Next, in step S130, the camera CPU 121 determines whether the aberration amount indicated by the aberration amount information is small, medium, or large. If the aberration amount is small, the camera CPU 121 proceeds to step S140 and selects the defocus amount in the spatial frequency domain of level 1 for AF. If the aberration is large, it proceeds to step S141 and selects the defocus amount in the spatial frequency domain of level 3 for AF. If the aberration amount is medium, it proceeds to step S142 and selects the defocus amount in the spatial frequency domain of level 2 for AF.

[0074] In other words, the camera CPU 121 detects the amount of defocus used for autofocus in a spatial period number band corresponding to the amount of aberration.

[0075] While the explanation described the case where the imaging optical system is a soft-focus lens, any imaging optical system with large aberrations will suffice, even if it's not a variable-aberration type like a soft-focus lens. Furthermore, even with a setting that results in large aberrations, the aberrations are reduced when the F-number is large, so the spatial frequency band selected for AF may be changed according to the F-number. When the F-number is large, information indicating that the amount of aberration is small may be transmitted from the soft-focus lens to the camera body via communication. [Examples]

[0076] Next, Embodiment 2 of the present invention will be described. In this embodiment as well, the camera CPU 121 detects the amount of defocus in spatial frequency bands of levels 1, 2, and 3, similar to Embodiment 1.

[0077] On the other hand, in interchangeable lenses, Flg1, Flg2, and Flg3 are stored in memory 152 as flags (information related to the spatial frequency band for focus detection) corresponding to spatial frequency bands of levels 1, 2, and 3, respectively, as shown in Figure 1. The lens CPU 151 then reads from memory 152 flags corresponding to the magnitude of the aberration amount of the variablely set imaging optical system (for example, flags indicating large, medium, and small), or flags indicating numerical values ​​corresponding to the aberration amount, and notifies the camera CPU 121. The camera CPU 121, upon receiving the flag notification, performs autofocus using the defocus amount in the spatial frequency band of the level corresponding to the flag.

[0078] Specifically, the camera CPU 121 performs autofocus using the amount of defocus in the spatial frequency band of level 1 when Flg1 is notified, and using the amount of defocus in the spatial frequency band of level 2 when Flg2 is notified. Furthermore, when Flg3 is notified, it performs autofocus using the amount of defocus in the spatial frequency band of level 3.

[0079] The camera CPU 121 and lens CPU 151 perform the above-described processes according to the computer program.

[0080] Alternatively, the lens CPU 151 may notify the camera CPU 121 of the spatial frequency band value (e.g., 10 lines / mm) as information regarding the spatial frequency band for focus detection, rather than a flag indicating the spatial frequency band for focus detection. In this case, the camera CPU 121 will perform autofocus using the defocus amount that matches that value.

[0081] According to the embodiments described above, even when performing focus detection through an imaging optical system with large aberrations (regardless of the amount of aberration), good focus detection results can be obtained. In the embodiments described above, the case in which autofocus is performed using the focus detection results was explained, but distance measurement to the subject may also be performed using the focus detection results. This will also yield good distance measurement results.

[0082] The focus detection methods described in each embodiment can be implemented not only in interchangeable-lens cameras and integrated-lens cameras as described above, but also in various other devices such as video cameras, mobile phones equipped with cameras, personal computers, and game consoles.

[0083] Furthermore, as a variation of the above embodiment, the configuration of the lens device as an interchangeable lens will be described in more detail. The lens device has an optical element that changes aberrations. This optical element can achieve a so-called soft focus effect through aberrations. When the user operates an operating member (not shown) provided on the lens device, this optical element is driven and the degree of the soft focus effect changes. The lens device has a communication control means (not shown) and is configured to communicate with the lens device via contacts provided on the camera mount.

[0084] When the camera is powered on and power is supplied to the lens device, an initial communication is performed between the camera and the lens device to exchange attribute information. In this initial communication, the lens device sends information to the camera indicating that it has an optical element that changes aberration, or that it is possible to change aberration, to the imaging device. This enables communication between the lens device and the camera in response to changes in aberration, and enables processing by the camera in response to changes in aberration, as described in the above embodiment. When the operating member is operated by the user, the lens device sends information to the camera corresponding to the amount of aberration that changes in response to this operation. A value of zero in this information is the flag described in the above embodiment. [Examples]

[0085] Next, Embodiment 3 of the present invention will be described. In Embodiment 3, bracket imaging is performed while changing the amount of aberration, which is the aberration state of the imaging optical system, so that the user can select an image with a desired amount of aberration, i.e., a degree of soft focus.

[0086] Figure 16 shows the configuration of the camera in this embodiment. In this figure, components that are the same as those shown in Figure 1 are denoted by the same reference numerals as in Figure 1 and are described accordingly. In this embodiment as well, the imaging optical system may be provided on the interchangeable lens, but the lens CPU 151 and lens memory 152 shown in Figure 1 are omitted from Figure 16.

[0087] In this embodiment, a soft focus effect is obtained by moving the first lens group 101 and the second lens group 103 in the direction of the optical axis. The soft focus drive circuit 129' drives the first and second lens groups 101 and 103 by controlling the soft focus actuator 111' based on a soft focus command from the camera CPU 121.

[0088] Furthermore, the internal memory of the camera CPU 121 stores correction value calculation coefficients necessary for AF using the output signal from the image sensor 107, similar to the first embodiment. Multiple correction value calculation coefficients are provided, corresponding to the focus state corresponding to the position of the third lens group 105, the amount of aberration corresponding to the positions of the first lens group 101 and the second lens group 103, the aperture value (F-number) of the imaging optical system, and the set pupil distance and pixel size of the image sensor 107. When performing AF, the camera CPU 121 calculates a correction value from the correction value calculation coefficient corresponding to the combination of focus state, amount of aberration, F-number, set pupil distance and pixel size, and the image height on the image sensor 107.

[0089] As explained in Example 1, if the imaging optical system is provided in the interchangeable lens, a memory for storing the correction value calculation coefficient may be provided in the interchangeable lens, and the camera body may calculate the correction value using the correction value calculation coefficient obtained by communication from the interchangeable lens during autofocus.

[0090] The group of control switches 132' includes a power switch, a shutter release (image trigger) switch, a soft focus operation switch, an image mode selection switch, and the like.

[0091] The flowchart in Figure 13 shows the aberration bracketing imaging process that the camera CPU 12 performs according to the computer program in this embodiment.

[0092] Aberration bracketing is an imaging technique that acquires multiple images with varying aberration levels by moving the first and second lens groups 101 and 103, which are soft-focus lens groups, along the optical axis to change the amount of aberration (degree of soft focus) of the imaging optical system. Aberration bracketing may be one of the functions that the user can select through the camera's menu screen, or it may be performed by operating an aberration bracketing switch provided on the operation switch group 132' (or interchangeable lens) by the user. In an interchangeable lens camera, when aberration bracketing is instructed by the user, the camera notifies the interchangeable lens that aberration bracketing has been instructed. Furthermore, when an interchangeable lens including a soft-focus lens is attached to an interchangeable lens camera, the interchangeable lens may notify the camera that aberration bracketing is possible.

[0093] In step S151, the camera CPU (setting means) 12, which has started the aberration bracketing imaging process, sets the number of imaging cycles N and the aberration amount change range AB for aberration bracketing imaging. The number of imaging cycles N and the aberration amount change range AB may be set by the camera CPU 12 according to the number and range specified in advance by the user, or they may be set automatically by the camera CPU 12.

[0094] The camera CPU 12 then decides to take five images with five different aberration values: -2, -1, 0, +1, and +2, for example, if the number of images taken N=5 and the aberration range AB=±2 are set. An aberration of 0 means there is no aberration, and the larger the absolute value of the aberration, the greater the aberration and the stronger the degree of soft focus. The aberration can be expressed with a sign (+ or -) and an integer as described above, or it can be expressed with natural numbers or letters, etc., and there are no limitations on the method of expression.

[0095] Next, in step S152, the camera CPU 12 sets the first of the multiple aberration amounts set in step S151 (for example, -2) as the current aberration amount.

[0096] Next, in step S153, the camera CPU 12 controls the soft focus actuator 111' to move the first and second lens groups 101 and 103 to positions corresponding to the aberration amount set in step S151. If the imaging optical system is provided in the interchangeable lens, the camera CPU 12 commands (controls) the drive of the first and second lens groups 101 and 103 to positions corresponding to the aberration amount set for the interchangeable lens. This command is given each time the aberration amount setting is changed.

[0097] As shown in Figures 14(a) and (b), if the interchangeable lens is provided with an aberration ring that can rotate around the optical axis, the soft focus actuator 111' may be configured to rotate the aberration ring, thereby driving the first and second lens groups 101 and 103 in the direction of the optical axis. The illustrated aberration ring has aberration amounts of -2, -1, 0, +1, and +2 indicated around its circumference, and the aberration amount at the position of the mark provided on the fixed cylinder of the interchangeable lens is displayed to the user as the current aberration amount. Alternatively, if the soft focus actuator 111' is not provided, the user may manually rotate the aberration ring to move the first and second lens groups 101 and 103 and change the aberration amount.

[0098] Next, in step S154, the camera CPU 12 calculates the defocus amount using the focus detection process shown in Figure 7, based on the aberration amount set up to step S153, and drives the third lens group 105 to perform autofocus (AF) according to the defocus amount. In this step, AF is performed to correct the focus shift caused by the change in aberration amount and to acquire an image in focus on the subject regardless of the aberration amount. At this time, as explained using Figure 11, the camera CPU 12 selects the defocus amount in the spatial frequency domain (level) according to the aberration amount set in step S152.

[0099] Next, in step S155, the camera CPU 12 starts aberration bracketing imaging for the number of imaging cycles N set in step S151, and records the image obtained from each imaging cycle into the flash memory 133.

[0100] Next, in step S156, the camera CPU 12 determines whether or not the N-fold aberration bracket imaging is complete. If it is not complete, it returns to step S152 to set the next aberration amount, and then performs the next imaging after driving the first and second lens groups 101 and 103 (step S153) and focusing (step S154). On the other hand, once the aberration bracket imaging is complete, the aberration bracket imaging process is terminated and the obtained N images are displayed on the display 131.

[0101] Figures 15(a) to 15(e) show examples of five images obtained by aberration bracketing, each with different aberration amounts. Compared to the image with an aberration of 0 shown in Figure 15(c), the images with an aberration of +1 shown in Figure 15(b) and an aberration of -1 shown in Figure 15(d) have a slightly higher degree of soft focus. Furthermore, the images with an aberration of +2 shown in Figure 15(a) and an aberration of -2 shown in Figure 15(e) have an even higher degree of soft focus. Note that the absolute values ​​of the aberrations are the same (1 and 2) in the images of Figures 15(b) and 15(d), respectively, but the movement directions of the first and second lens groups 101 and 103 are opposite, resulting in different images.

[0102] The degree of soft focus varies depending on the arrangement of multiple subjects, as well as imaging conditions such as the f-number and subject distance. Therefore, by displaying multiple images obtained from actual imaging with different aberration amounts, as in this embodiment, the user can easily select an image with the desired degree of soft focus.

[0103] In this embodiment, we have described a case where bracket imaging is performed while changing the amount of aberration, but parameters other than the amount of aberration may also be changed during bracket imaging. For example, in addition to the amount of aberration, the aperture state (F-number) may also be changed. In this case, aberration bracket imaging is first performed with an initial F-number (e.g., F=4), and then aberration bracket imaging is performed again with the next F-number (e.g., F=5.6). This makes it possible to acquire multiple images with different amounts of aberration for each F-number, thereby increasing the number of soft focus levels that can be selected by the user. [Examples]

[0104] Next, we will describe Example 4. In this example, the amount of defocus is corrected according to the amount of aberration in the imaging optical system.

[0105] This section describes the case where a soft-focus lens (interchangeable lens) with adjustable spherical aberration is attached to an interchangeable-lens camera. The soft-focus lens communicates information about the set aberration amount (hereinafter referred to as aberration amount information) to the camera via communication.

[0106] The flowchart in Figure 17 shows the focus detection process that the camera CPU 12 executes according to the computer program in this embodiment. The process from step S200 to step S250 is the same as steps S10 to S60 in Figure 7.

[0107] In step S250, when the amount of defocus is calculated, the camera CPU 12 corrects the amount of defocus, which is the focus detection result, in step S260 using a correction coefficient as correction information, which will be described below.

[0108] The flowchart in Figure 18 shows the process of calculating (acquiring) the correction coefficient. In step S300, the camera CPU 12 receives aberration amount information notified from the soft focus lens in step S310. The aberration amount information may be aberration information expressed using Zernike coefficients, such as wavefront aberration, or if the camera CPU 12 recognizes that a soft focus lens is attached using the lens ID or the like, it may be information on the set value of the aberration amount in the soft focus lens.

[0109] Next, in step S320, the camera CPU 12 determines whether or not the user has selected to correct the amount of defocus, and if correction is performed, which correction coefficient calculation method has been selected. In this embodiment, as the method for calculating the correction coefficient, it is possible to select a method for calculating a correction coefficient according to the amount of aberration (aberration-considering correction coefficient) and a method for calculating a correction coefficient that does not depend on the amount of aberration (aberration-unconsidering correction coefficient).

[0110] If the camera CPU 12 has selected not to correct the amount of defocus, it proceeds to step S330, sets the correction coefficient to 1, and proceeds to step S360. In this case, the amount of defocus calculated in step S250 is used directly for autofocus.

[0111] On the other hand, if the method for calculating the aberration-aware correction coefficient is selected, the process proceeds to step S340; if the method for calculating the aberration-unaware correction coefficient is selected, the process proceeds to step S350.

[0112] In step S340, the camera CPU 12 calculates a correction coefficient for each defocus amount and F-number using aberration information received from the soft focus lens. For example, if the fourth-order Zernike coefficient Z, which represents spherical aberration, is obtained as aberration information from the soft focus lens, the correction coefficient Kgain is calculated using the following equation (2). Kgain = m1 × Z 2 +m1×Z+m0 (2) In equation (2), m2, m1, and m0 are fitting coefficients obtained when the correction coefficient is fitted using the Zernike coefficient Z. The camera CPU 12 stores the fitting coefficients as table data for each representative defocus amount and F-number, and fitting coefficients other than the representative defocus amount and F-number are obtained by linear interpolation. The fitting may be first-order or third-order or higher. Also, fitting may be performed using multiple Zernike coefficients.

[0113] Furthermore, the camera CPU 12 may store correction coefficients for each amount of defocus, f-number, and aberration in advance, and select a correction coefficient according to the amount of defocus, f-number, and aberration when correcting the amount of defocus. In addition, the correction coefficient may be varied according to the spatial frequency band (level), in addition to the amount of defocus, f-number, and aberration.

[0114] The camera CPU 12 corrects the amount of defocus in step S360 using the correction coefficient obtained in this way. Specifically, it corrects the amount of defocus using equation (3).

[0115] d = p × K × K gain (3) In equation (3), d is the corrected defocus amount, p is the image displacement amount, and K is the conversion coefficient used to convert the image displacement amount to the defocus amount.

[0116] Figures 19(a) and 19(c) show examples of correction coefficients corresponding to the amount of spherical aberration. The horizontal axis in each figure represents the amount of defocus, with the left side being the front-focused side and the right side being the back-focused side, with "focus" being approximately zero. The vertical axis represents the correction coefficient. Figure 19(a) shows the correction coefficient when the amount of aberration is small. In this case, the correction coefficient is roughly symmetrical between the front-focused side and the back-focused side, with "focus" in between. On the other hand, Figures 19(b) and 19(c) show the correction coefficient when the amount of aberration is large. In these cases, the correction coefficient is asymmetrical between the front-focused side and the back-focused side, with "focus" in between.

[0117] Furthermore, in step S350, the camera CPU 12 calculates the amount of defocus and the correction coefficient for each f-number without using aberration information. Then, in step S360, the amount of defocus is corrected using these correction coefficients.

[0118] In this embodiment, we have described the case where a soft-focus lens with variable aberration is attached to the camera. However, even if the aberration is not variable, or if a lens with large aberrations is attached to the camera, the same processing as in this embodiment can be applied. (Other examples) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0119] The embodiments described above are merely representative examples, and various modifications and changes can be made to each embodiment when implementing the present invention. [Explanation of symbols]

[0120] 101-106 Lens group or aperture (imaging optical system) 107 Image sensor 121 Camera CPU (Focus detection means)

Claims

1. An image sensor including a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system, The imaging optical system has focus detection means that performs focus detection using a pair of focus detection signals generated using the output signals from the pair of focus detection pixels, The focus detection means is It is possible to perform the aforementioned focus detection in multiple spatial frequency bands, An imaging device characterized by obtaining focus detection results in different spatial frequency bands from among multiple spatial frequency bands, depending on the amount of spherical aberration of the imaging optical system.

2. The lens device having the imaging optical system is detachable from the imaging device. The imaging apparatus according to claim 1, wherein the focus detection means obtains information regarding the amount of spherical aberration or information regarding different spatial frequency bands for focus detection depending on the amount of spherical aberration from the lens device, and obtains the focus detection result to be used in a spatial frequency band selected from among the plurality of spatial frequency bands according to the information regarding the spatial frequency band for focus detection obtained from the lens device.

3. The lens device having the imaging optical system is detachable from the imaging device. The imaging apparatus according to claim 1, wherein the focus detection means acquires information regarding the amount of spherical aberration or information regarding different spatial frequency bands for focus detection depending on the amount of spherical aberration from the lens device, and selects the focus detection result to be used from among the multiple spatial frequency bands according to the information regarding the spatial frequency bands for focus detection acquired from the lens device.

4. The imaging apparatus according to any one of claims 1 to 3, characterized in that the focus detection means obtains the focus detection result to be used in a spatial frequency band that is lower as the amount of spherical aberration increases.

5. The imaging apparatus according to any one of claims 1 to 4, characterized in that the focus detection means obtains the focus detection result to be used in different spatial frequency bands depending on the F value of the imaging optical system.

6. The imaging device according to any one of claims 1 to 5, characterized in that it controls the focus of the imaging optical system based on the focus detection result used.

7. A lens device having an imaging optical system, which is detachably attached to an imaging device according to any one of claims 1 to 6, A storage means for storing information regarding the amount of spherical aberration of the imaging optical system or information regarding different spatial frequency bands for focus detection depending on the amount of spherical aberration, A lens device characterized by having a notification means for notifying the imaging device of information relating to the spatial frequency band for focus detection.

8. The lens device according to claim 7, characterized in that the amount of spherical aberration of the imaging optical system can be changed.

9. A lens device that can be attached to an imaging device according to any one of claims 1 to 6, An operating component that accepts user input, An optical member that changes spherical aberration in response to operation on the aforementioned operating member, It has a communication control means for communicating with the imaging device, The aforementioned communication control means is Information indicating that the imaging device has an optical element that changes the spherical aberration is transmitted to the imaging device. A lens device characterized by transmitting information corresponding to the amount of spherical aberration that changes in response to an operation performed by a user on the operating member.

10. A control method for an imaging device having an image sensor that includes a pair of focus detection pixels that receive light beams that have passed through different regions in the exit pupil of the imaging optical system, The steps include generating a pair of focus detection signals using the output signals from the pair of focus detection pixels, A control method for an imaging device, characterized by comprising the step of obtaining a focus detection result to be used in a spatial frequency band that differs from a plurality of spatial frequency bands capable of detecting the focus of the imaging optical system using the pair of focus detection signals, depending on the amount of spherical aberration of the imaging optical system.

11. A control method for a lens device having an imaging optical system, which is detachably attached to an imaging device using the control method described in claim 10, The steps include storing information regarding the amount of spherical aberration of the imaging optical system or information regarding different spatial frequency bands for focus detection depending on the amount of spherical aberration, A method for controlling a lens device, characterized by comprising the step of notifying the imaging device of information relating to the spatial frequency band for focus detection.

12. A control method for a lens device having an optical element that is attachable to an imaging device according to any one of claims 1 to 6 and changes spherical aberration in response to operation of an operating member by a user, The steps include transmitting information to the imaging device indicating that it has an optical element that changes the spherical aberration, A method for controlling a lens device, characterized by comprising the step of transmitting information corresponding to the amount of spherical aberration that changes in response to an operation of the operating member by a user.

13. A computer program characterized by causing the computer of the imaging device to perform a process according to the control method described in claim 10.

14. A computer program characterized by causing the computer of the lens device to perform a process according to the control method described in claim 11.

15. A computer program characterized by causing the computer of the lens device to perform a process according to the control method described in claim 12.

Images