Focus controller, imaging apparatus, and focus control method

Abstract

To perform appropriate search operations in focusing.SOLUTION: A focus controller has focus detection means 129 that performs focus detection, and control means 125 that controls the drive of a focus lens included in an optical system on the basis of a focus detection result obtained from the focus detection. The control means performs control so that the relationship between the rotation direction of a ring member that can be operated to rotate by a user and the drive direction of the focus lens, and the relationship between the rotation direction of the ring member and a search direction, correspond to each other, and starts search operations of performing focus detection at a predetermined period while moving the focus lens in correspondence with the amount of rotation of the ring member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to focus control. [Background technology]

[0002] Some imaging devices perform a search operation that moves a focus lens to search for a focus position. Patent Document 1 discloses a technology in which a user specifies the distant or near side and performs a search process limited to the distant or near side, with the search start position as the end point, thereby enabling the device to quickly focus on a subject desired by the user. The technology also discloses a technology in which a first and second switch are provided, and when the first switch is turned on, a search process is performed on the distant side, with the current lens position as the end point on the near side. Furthermore, when the second switch is turned on, a search process is performed on the near side, with the current lens position as the end point on the distant side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-164051 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method disclosed in Patent Document 1 requires the use of multiple switches when performing search processing, which makes the operation complicated and makes it difficult to perform intuitive operations.

[0005] The present invention provides a focus control device that enables search processing to be performed with more intuitive operations. [Means for solving the problem]

[0006] A focus control device as one aspect of the present invention comprises a focus detection means for performing focus detection, and a control means for controlling the drive of a focus lens included in an optical system based on the focus detection result obtained by the focus detection, wherein the control means controls the relationship between the rotation direction of a ring member that can be rotated by a user and the drive direction of the focus lens, and the relationship between the rotation direction of the ring member and the search direction so that they correspond to each other, and starts a search operation that performs focus detection at a predetermined cycle while moving the focus lens in accordance with the amount of rotation of the ring member. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a focus control device that allows search processing to be performed with more intuitive operations. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a configuration of an imaging device. [Figure 2] FIG. 2 is a diagram showing a pixel array of an imaging element. [Figure 3] 1A is a plan view of a pixel and FIG. 1A is a cross-sectional view of FIG. [Figure 4] FIG. 2 is a diagram illustrating the relationship between pixels and pupil division. [Figure 5] FIG. 2 is a diagram illustrating the relationship between an image sensor and pupil division. [Figure 6] 10A and 10B are diagrams illustrating the relationship between the defocus amount and the image shift amount. [Figure 7] 10 is a flowchart showing an imaging process. [Figure 8] 10 is a flowchart showing a search AF process. [Figure 9] 10 is a flowchart showing a process for calculating a focus drivable range. [Figure 10] FIG. 2 is a diagram showing the positional relationship between a subject and a background. [Figure 11] FIG. 10 is a diagram showing signals of a subject and a background. [Figure 12]10A and 10B are diagrams illustrating the relationship between the focus lens position and the focus detection result. [Figure 13] 10A and 10B are diagrams showing the relationship between a search direction, a search start position, a focus lens position, a focus driveable range, a focus detection result, and a drive amount. [Figure 14] 10 is a flowchart showing a process of determining whether to perform search AF. [Figure 15] FIG. 10 is a diagram showing an example of a function assignment setting screen for the rotary operation unit. [Figure 16] FIG. 10 is a diagram showing an example of a display screen during execution of search AF. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] (Embodiment 1) The imaging system 10 of the first embodiment shown in FIG. 1 is an interchangeable-lens digital camera system capable of image-plane phase-difference detection autofocus (hereinafter referred to as image-plane phase-difference AF). This embodiment is applicable to digital cameras with an integrated lens and digital video cameras. Furthermore, the present embodiment is applicable to various devices, such as terminal devices such as tablets and smartphones that allow focus control instructions using a ring member or remote focus control using a ring member, as well as surveillance cameras, in-vehicle cameras, and medical cameras. Furthermore, the present embodiment is not limited to image-plane phase-difference AF, and other focus detection methods may be employed as long as information regarding subject distance is obtained. For example, a ToF (Time of Flight) method is considered, in which light (infrared light or laser) is emitted, hits the subject, reflects, and returns to calculate the distance. Another possible method is to attach an RFID (Radio Frequency Identification) tag or UWB (Ultra-Wideband) tag to the subject, and an antenna receives a signal from the tag to identify the subject's location.

[0011] <Device configuration> The imaging system 10 is made up of a lens unit 100 and a camera body 120 serving as an imaging device. The lens unit 100 is detachably connected to the camera body 120 via a mount M indicated by the dotted line in the center of the figure.

[0012] Lens unit 100, which forms a subject image, has a first lens group 101, an aperture 102, a second lens group 103, a focus lens group (hereinafter referred to as focus lens) 104, and a drive unit and a control unit, which will be described later. Lens unit 100 forms a photographic optical system that includes focus lens 104 and forms an image of the subject. Lens unit 100 also has a lens barrel that houses the first to fourth lens groups 101 to 104, and a rotation operation unit 105, which is a ring member that can be rotated by the user, is attached to the outer periphery of the lens barrel.

[0013] The first lens group 101 is disposed at the tip of the lens unit 100 and is held so as to be able to move forward and backward in the optical axis direction OA. Hereinafter, the optical axis direction OA is referred to as the Z direction, and the direction in which the subject is viewed from the camera is referred to as the positive direction. In this embodiment, the origin 0 of the Z direction axis corresponds to the position of an image sensor 122 in the camera body 120, which will be described later.

[0014] The aperture 102 adjusts the amount of light during shooting by adjusting its opening diameter. The aperture 102 also functions as a mechanical shutter that controls exposure time during still image shooting. The aperture 102 and second lens group 103 can move together in the optical axis direction OA, and by moving in conjunction with the first lens group 101, a zoom function is achieved.

[0015] The focus lens 104 is movable forward and backward in the optical axis direction OA, and the subject distance (focusing distance) at which the lens unit 100 focuses changes depending on the position of the focus lens 104. In this embodiment, by controlling the position of the focus lens 104 in the optical axis direction OA, an autofocus function is realized that detects subject distance information (focus detection) and adjusts the focusing distance.

[0016] The lens unit 100 has a drive / control system (including devices, circuits, program code, and the like). The drive system of the drive / control system includes a zoom actuator 111, an aperture / shutter actuator 112, a focus actuator 113, a zoom driver 114, an aperture / shutter driver 115, and a focus driver 116. The control system that controls the drive system includes a lens MPU 117 and a lens memory 118.

[0017] The zoom actuator 111 drives the first lens group 101 and the second lens group 103 forward and backward in the optical axis direction OA, thereby performing zoom control to change the angle of view of the photographing optical system. The iris / shutter actuator 112 controls the aperture diameter of the iris 102 to adjust the amount of light for photographing, and controls the opening and closing operation of the iris 102 to control the exposure time during photographing. The focus actuator 113 drives the focus lens 104 forward and backward in the optical axis direction OA to perform autofocus operation, and also has the function of detecting the current position of the focus lens 104.

[0018] The zoom driver 114 drives the zoom actuator 111 in response to a user's zoom operation or a control value of the lens MPU 117. The iris / shutter driver 115 drives the iris / shutter actuator 112 to control the aperture diameter or opening / closing operation of the iris 102. The focus driver 116 drives the focus actuator 113 to drive the focus lens 104 forward and backward in the optical axis direction OA to perform an autofocus operation (focus adjustment operation). The rotation position detector 106 detects the rotation position of the rotation operation unit 105 and transmits information about the rotation position to the lens MPU 117. The lens MPU 117 can obtain the operation amount (rotation direction and rotation amount) of the rotation operation unit 105 from the amount of change in the rotation position, and can also calculate the rotation speed.

[0019] The lens MPU 117 performs all calculations and controls related to the photographic optical system and controls the zoom driver 114, aperture / shutter driver 115, focus driver 116, rotation position detector 106, and lens memory 118. The lens MPU 117 is connected to the camera MPU 125 via a mount M so that commands and data can be exchanged. For example, the lens MPU 117 detects the current position of the focus lens 104 and notifies the camera MPU 125 of lens position information in response to a request. This lens position information includes information such as the position of the focus lens 104 in the optical axis direction OA, the position and diameter of the exit pupil in the optical axis direction OA when the optical system is not moving, and the position and diameter of the lens frame that limits the light beam of the exit pupil in the optical axis direction OA. The lens MPU 117 also controls the zoom driver 114, aperture / shutter driver 115, and focus driver 116 in response to a request from the camera MPU 125. Furthermore, in this embodiment, the lens MPU 117 can assign a function to the rotary operation unit 105 in response to a request from the camera MPU 125. Furthermore, the lens MPU 117 can notify the camera MPU 125 of information on the operation amount (rotation direction and rotation amount) of the rotary operation unit 105 detected by the rotation position detection unit 106 and the rotation speed calculated by the lens MPU. For example, when the manual focus (MF) function is assigned to the rotary operation unit 105, the lens MPU 117 accepts the operation of the rotary operation unit 105 and controls the focus drive unit 116 in response to the acceptance. As a result, the focus lens 104 moves in response to the operation of the rotary operation unit 105.

[0020] The lens memory 118 stores optical information necessary for image plane phase-difference AF in advance. The lens memory 118 also stores, for example, a defocus map indicating the correspondence between the position and movement amount of the focus lens 104 and the defocus amount. As will be described later, the defocus map is generated by calculating the image shift amount at each pixel position of the first focus detection signal and the second focus detection signal through correlation calculation and converting the image shift amount into a defocus amount. When the lens MPU 117 receives a request from the camera MPU 125 to change the defocus amount by a predetermined amount, it refers to the defocus map stored in the lens memory 118. The lens MPU 117 then controls the focus actuator 113 to move the focus lens 104 by a distance corresponding to the predetermined amount.

[0021] The camera MPU 125 controls the operation of the lens unit 100 by executing programs stored in, for example, the ROM 125a or the lens memory 118. The lens memory 118 also stores optical information about the photographic optical system of this embodiment.

[0022] The camera body 120 has an optical low-pass filter 121, an image sensor 122, and a drive / control system (described later). The optical low-pass filter 121 reduces false colors and moire in captured images.

[0023] The image sensor 122 is composed of, for example, a CMOS image sensor and its peripheral circuitry. A CMOS image sensor has a photoelectric conversion element provided in each pixel that receives light, and has a pixel group (image sensor surface) in which a plurality of unit pixels are arranged two-dimensionally, with each pixel acting as a unit pixel. The image sensor 122 has a plurality of focus detection pixels that receive light beams that pass through different pupil regions of the imaging optical system, and each pixel can output an independent signal. This makes it possible to calculate the amount of defocus, which is the result of focus detection using image sensor phase-difference AF. The image sensor 122 also has a plurality of imaging pixels that receive light beams that pass through the entire exit pupil of the imaging optical system that forms an image of the subject, and generate an image signal of the subject.

[0024] The drive / control system of the camera body 120 includes an image sensor drive unit 123, an image processing unit 124, a camera MPU 125 that controls the entire camera body 120, a display unit 126, operation switches 127, a memory 128, and a phase-difference AF unit 129. The image sensor drive unit 123 controls the charge accumulation operation of the image sensor 122 and converts image signals read from the image sensor 122 into digital signals and sends them to the camera MPU 125. The image processing unit 124 performs various image processing such as gamma conversion, color interpolation, and JPEG compression on the image signals read from the image sensor 122. The image processing unit 124 also generates signals for focus detection using an image plane phase-difference method, which will be described later, signals for exposure adjustment, signals for white balance adjustment, and signals for subject detection. In this embodiment, signals for focus detection (for phase-difference AF), signals for exposure adjustment, signals for white balance adjustment, and signals for subject detection are generated. However, for example, a signal for exposure adjustment, a signal for white balance adjustment, and a signal for subject detection may be generated as a common signal. Also, the combination of common signals is not limited to this.

[0025] The camera MPU 125 has a microprocessor and performs all calculations and control related to the camera body 120. This controls the image sensor drive unit 123, image processing unit 124, display unit 126, operation switches 127, memory 128, phase difference AF unit 129, AE unit 130, subject detection unit 132, lens function allocation unit 133, and lens control unit 134. The camera MPU 125 is connected to the lens MPU 117 via signal lines arranged in the mount M. This allows the camera MPU 125 to issue to the lens MPU 117 requests to acquire the lens position, requests to zoom drive, aperture drive, or lens drive at a predetermined drive amount, and requests to acquire optical information specific to the lens unit 100.

[0026] The camera MPU 125 has built-in ROM 125a that stores programs for controlling the operation of the camera, RAM 125b that stores variables, and EEPROM 125c that stores various parameters. The camera MPU 125 reads out the programs stored in ROM 125a, expands them into RAM 125b, and executes them to perform focus detection processing, subject detection processing, exposure adjustment processing, and white balance adjustment processing, which will be described later.

[0027] The display unit 126 has a display device such as an LCD (liquid crystal) panel or organic EL display, and displays various information related to each operation mode of the camera. The operation modes of the camera include, for example, a shooting mode for shooting still images and videos, and a playback mode for playing back captured images stored in memory 128. In the shooting mode, information related to the camera's shooting mode, a preview image before shooting and a confirmation image after shooting, and an in-focus state image during focus detection are displayed. The display unit also sequentially displays videos being shot.

[0028] The operation switches 127 include a shutter switch, a power switch, a zoom switch, a mode change switch, etc. The memory 128 is a flash memory that is detachable from the camera, and records captured images.

[0029] The phase-difference AF section 129 performs focus detection processing using a phase-difference detection method based on a pair of image signals (signals for phase-difference AF) with different parallaxes for focus detection obtained from the image sensor 122 and the image processing section 124. The image processing section 124 generates a pair of image data with different parallaxes formed by light beams passing through a pair of pupil regions of the imaging optical system, and the phase-difference AF section 129 calculates the amount of focus shift (defocus amount) based on the amount of shift between the pair of image data. In this way, the phase-difference AF section 129 performs phase-difference AF (image plane phase-difference AF) using the output signal of the image sensor 122 without using a dedicated AF sensor.

[0030] Phase difference AF unit 129 has an acquisition block 129a and a calculation block 129b. The operations of these will be described later. At least a part of focus adjustment unit 129 (a part of acquisition block 129a or zero calculation block 129b) may be provided in camera MPU 125. The focus adjustment operation performed by phase difference AF unit 129 will be described later. Phase difference AF unit 129 has an autofocus (AF) function that controls the position of focus lens 104 using the focus detection result.

[0031] The subject detection unit 132 performs subject detection processing based on the subject detection signal generated by the image processing unit 124 to detect the type, part, and state of the subject (detection type), the position and size of the subject (detection area), and the like.

[0032] The lens function allocation unit 133 selects a function to be allocated to the rotary operation unit 105. Any one of a plurality of functions can be selectively allocated to the rotary operation unit 105. In addition to the manual focus (MF) function described above, it is possible to allocate a search AF control function (described later) that is unique to this embodiment. Other functions may also be included, such as an aperture operation function for adjusting the aperture diameter of the aperture 102 and an ISO sensitivity operation function for changing the ISO sensitivity of the image sensor 121. In this embodiment, the search AF control function described later is allocated to the rotary operation unit 105. A method for setting the functions to be allocated to the rotary operation unit 105 will be described later.

[0033] The AE unit 130 performs photometry based on exposure adjustment (AE) signals obtained from the image sensor 122 and the image processing unit 124, thereby appropriately controlling the photographing conditions.

[0034] The AE unit 130 controls the exposure conditions by performing photometry based on exposure adjustment signals obtained from the image sensor 122 and the image processing unit 124. Specifically, it calculates the exposure amount at the currently set aperture value, shutter speed, and ISO sensitivity, and calculates appropriate aperture value, shutter speed, and ISO sensitivity for image capture based on the difference between the calculated exposure amount and a predetermined appropriate exposure amount, and sets these as exposure conditions. This realizes automatic exposure control (AE).

[0035] The white balance adjustment unit 131 performs white balance adjustment processing based on white balance adjustment signals obtained from the image sensor 122 and the image processing unit 124. The white balance adjustment unit 131 has an automatic white balance adjustment (AWB) function that adjusts color weighting based on the difference between white balance parameters obtained from the white balance adjustment signals and predetermined appropriate white balance parameters.

[0036] The camera body 120 of this embodiment can perform AF, AE, and AWB in combination with subject detection, and can select the position within the imaging range where AF, AE, and AWB are performed according to the subject detection results.

[0037] <Image sensor configuration> Fig. 2 shows the array of imaging pixels in the image sensor 122 as a two-dimensional CMOS sensor in a range of 4 columns x 4 rows, and the array of focus detection pixels in a range of 8 columns x 4 rows. In the 2 columns x 2 rows imaging pixel group 200 shown in Fig. 2, an imaging pixel 200R having a spectral sensitivity of R (red) is arranged in the upper left, imaging pixels 200G having a spectral sensitivity of G (green) are arranged in the upper right and lower left, and an imaging pixel 200B having a spectral sensitivity of B (blue) is arranged in the lower right. Furthermore, each imaging pixel is made up of a first focus detection pixel 201 and a second focus detection pixel 202 arranged in a 2 columns x 1 row.

[0038] By arranging a large number of such imaging pixel groups 200 on the imaging surface, it is possible to obtain a captured image and a focus detection signal.

[0039] Fig. 3(a) shows one imaging pixel (hereinafter simply referred to as pixel) 200G of the imaging element 122 shown in Fig. 2, viewed from the light receiving surface side (+z side) of the imaging element 122. Fig. 3(b) shows a cross section of the aa cross section of Fig. 3(a) viewed from the -y side.

[0040] Pixel 200G is provided with a microlens 305 for collecting incident light, and a photoelectric conversion unit 301 and a photoelectric conversion unit 302 that are divided into two in the x direction. The photoelectric conversion unit 301 and the photoelectric conversion unit 302 correspond to the first focus detection pixel 201 and the second focus detection pixel 202 shown in FIG. 2, respectively.

[0041] The photoelectric conversion units 301 and 302 may be pin structure photodiodes in which an intrinsic layer is sandwiched between a p-type layer and an n-type layer, or may be pn junction photodiodes in which the intrinsic layer is omitted. In the pixel 200G, a color filter 306 is provided between the microlens 305 and the photoelectric conversion units 301 and 302. The spectral transmittance of the color filter may be different for each photoelectric conversion unit, or the color filter may be omitted.

[0042] Light incident on pixel 200G is collected by microlens 305, dispersed by color filter 306, and then received by photoelectric conversion unit 301 and photoelectric conversion unit 302. In photoelectric conversion unit 301 and photoelectric conversion unit 302, pairs of electrons and holes are generated according to the amount of received light, and after being separated by a depletion layer, the negatively charged electrons are accumulated in the n-type layer, while the holes are discharged to the outside of image sensor 122 through a p-type layer connected to a constant voltage source (not shown).

[0043] The electrons stored in the n-type layers of the photoelectric conversion units 301 and 302 are transferred to the capacitance unit (FD) via the transfer gate and converted into a voltage signal.

[0044] Fig. 4 shows the correspondence between the pixel structure and pupil division of the image sensor 122 shown in Fig. 3. Fig. 4 shows a cross section of the pixel structure of the image sensor 122 shown in Fig. 3(a) viewed from the +y side and the pupil plane (pupil distance Ds) of the image sensor 122. Note that in Fig. 4, the x-axis and y-axis of the cross section of the image sensor 122 are shown inverted compared to Fig. 3 in order to correspond to the coordinate axes of the pupil plane of the image sensor 122.

[0045] 4, the first pupil partial region 501 is a region that can receive light by the first focus detection pixel 201, and is generally conjugate by the microlens 305 with the light receiving surface of the photoelectric conversion unit 301, whose center of gravity is decentered in the -x direction. The second pupil partial region 502 is a region that can receive light by the second focus detection pixel 202, and is generally conjugate by the microlens with the light receiving surface of the photoelectric conversion unit 302, whose center of gravity is decentered in the +x direction. Also in Fig. 4, the pupil region 500, which includes the first and second pupil partial regions 501, 502, is a region that can receive light by the entire pixel 200G, which includes the photoelectric conversion units 301, 302 (first and second focus detection pixels 201, 202).

[0046] As shown in Fig. 5, light beams that pass through a first pupil partial region 501 and a second pupil partial region 502 that are different from each other in a pupil region 500 of the imaging optical system are incident on pixels on the imaging plane 800 at different angles from each other and are received by a first focus detection pixel 201 and a second focus detection pixel 202. Fig. 5 shows an example in which the pupil region is divided into two in the horizontal direction, but the pupil may also be divided in the vertical direction.

[0047] A first focus detection signal is generated by combining photoelectric conversion signals from the first focus detection pixels 201 of multiple pixels, and a second focus signal is generated by combining photoelectric conversion signals from the second focus detection pixels 202. An image pickup signal with a resolution of the effective pixel number N is generated by adding the photoelectric conversion signals from the first and second focus detection pixels 201, 202 at each pixel. The second focus detection signal may also be generated by subtracting the first focus detection signal from the image pickup signal.

[0048] In the above description of the image sensor 122, a plurality of photoelectric conversion units are provided for each microlens, and focus detection signals and image generation signals are output from the photoelectric conversion units. However, the present invention is not limited to this. For example, the image sensor 122 may be configured to include image capture pixels used for image generation and focus detection pixels used for focus adjustment.

[0049] <Relationship between defocus amount and image shift amount> FIG. 6 shows the relationship between the defocus amount and the image shift amount between the first and second focus detection signals. As shown in FIG. 5, the pupil region of the imaging optical system is divided into a first pupil partial region 501 and a second pupil partial region 502. The defocus amount d is the distance from the imaging position of the subject image to the imaging plane 800, |d|, and a front-focus state in which the subject image is formed on the subject side of the imaging plane 800 is indicated by a negative sign (d<0). A back-focus state in which the subject image is formed on the opposite side of the imaging plane 800 from the subject side is indicated by a positive sign (d>0). In FIG. 6, subject 801 represents a subject in a focused state (d=0), and subject 802 represents a subject in a front-focus state (d<0). The front-focus state (d<0) and back-focus state (d>0) are collectively referred to as a defocus state (|d|>0).

[0050] In a front-focus state (d<0), light beams from the subject 802 that pass through the first and second pupil partial regions 501 and 502 are focused once and then spread to widths Γ1 and Γ2 around the center of gravity positions G1 and G2 of the light beams, respectively, forming blurred images on the imaging surface 800. First and second focus detection signals are generated when the blurred images are received by the first and second focus detection pixels 201 and 202. Therefore, the first and second focus detection signals are recorded as subject images of the subject 802 blurred to widths Γ1 and Γ2 at the center of gravity positions G1 and G2 on the imaging surface 800, respectively. The blur widths Γ1 and Γ2 of the subject image increase approximately proportionally as the magnitude of the defocus amount d, |d|, increases. Similarly, the magnitude |p| of the image shift amount p (the difference G1-G2 in the center of gravity positions of the light beams) between the first and second focus detection signals also increases roughly in proportion to the magnitude |d| of the defocus amount d. The same is true in the back-focus state (d>0), except that the direction of the image shift between the first and second focus detection signals is opposite to that in the front-focus state.

[0051] The phase difference AF unit 129 converts the amount of image shift into a defocus amount d using a conversion coefficient calculated based on the distance (baseline length) between the first and second focus detection pixels 201, 202, since the amount of image shift between the first and second focus detection signals increases as the amount of defocus increases.

[0052] <Image capture processing> The flowchart in FIG. 7 shows the imaging process that the camera MPU 125 executes in accordance with a program in this embodiment.

[0053] In step S701, the camera MPU 125 causes the phase-difference AF unit 129 to perform focus detection and acquires the defocus amount and its reliability as the focus detection result. Note that the defocus amount includes the defocus direction. Next, in step S702, the camera MPU 125 determines whether or not an AF instruction has been issued. If an AF instruction has been issued, the process proceeds to step S703. If an AF instruction has not been issued, the process proceeds to step S704. In step S703, the camera MPU 125 executes normal AF (image-plane phase-difference AF) processing and sets the drive amount of the focus lens 104 (hereinafter referred to as the focus drive amount) according to the defocus amount acquired in step S701. Then, the process proceeds to step S708.

[0054] In step S704, camera MPU 125 determines whether or not rotation operation unit 105 has been rotated based on the amount of operation of rotation operation unit 105 notified by lens MPU 117 in response to a request from camera MPU 125. If rotation operation has been performed, the process proceeds to step S705, and if rotation operation has not been performed, the process proceeds to step S701.

[0055] In step S705, the camera MPU 125 executes a search AF execution determination process, which will be described later.

[0056] In step S706, the camera MPU 125 determines whether a search instruction has been issued based on the determination in step S705. If a search instruction has been issued, the process proceeds to step S707, and if a search instruction has not been issued, the process proceeds to step S701.

[0057] In step S707, the camera MPU 125 executes search AF processing, and then proceeds to step S708. The search AF processing will be described later.

[0058] In step S708, the camera MPU 125 transmits the focus drive amount set in step S703 or step S707 to the lens MPU 117 to drive the focus lens 104.

[0059] In step S709, the camera MPU 125 determines whether the photographing optical system is in focus on the subject, and if it is determined that it is in focus, proceeds to step S710, and if it is determined that it is not in focus, proceeds to step S701.

[0060] In step S710, the camera MPU 125 captures an image for recording, and when the image capture is completed, this process ends.

[0061] <Search AF execution decision processing> Next, the search AF execution determination process in step S705 in FIG. 7 will be described.

[0062] FIG. 14 shows a flowchart of the search AF execution determination process executed by the camera MPU 125.

[0063] In step S1401, the camera MPU 125 acquires information on the operation amount (rotation direction and rotation amount) of the rotation operation unit 105 detected by the rotation position detection unit 106 of the lens unit 100 and the rotation speed calculated by the lens MPU 117.

[0064] In step S1402, the camera MPU 125 determines whether the amount of rotation of the rotation operation unit 105 is greater than a predetermined threshold value of rotation amount stored in advance in the ROM 125a. If the amount of rotation is greater than the threshold value of rotation amount, the process proceeds to step S1403. If the amount of rotation is equal to or less than the threshold value of rotation amount, the process proceeds to step S1405.

[0065] In step S1403, the camera MPU 125 determines whether the rotation speed of the rotation operation unit 105 is faster than a predetermined rotation speed threshold pre-stored in the ROM 125a. If the rotation speed is faster than the predetermined rotation speed threshold, the process proceeds to step S1404, and if the rotation speed is equal to or less than the predetermined rotation speed threshold, the process proceeds to step S1405.

[0066] In step S1404, the camera MPU 125 issues a search AF operation instruction because the rotation amount and rotation speed of the rotary operation unit 105 are greater than a predetermined amount and it is considered unlikely that this is a user error. On the other hand, in step S1405, the camera MPU 125 does not issue a search AF operation instruction because the rotation amount or rotation speed of the rotary operation unit 105 is less than a predetermined amount and it is considered likely that this is a user error.

[0067] When the processing in step S1404 or step S1405 is completed, the search AF execution determination processing ends.

[0068] <Search AF processing> Next, the search AF process in step S707 in Fig. 7 will be described. Fig. 8 shows a flowchart of the search AF process executed by the camera MPU 125. In the search AF (processing), a search operation (hereinafter simply referred to as search) is performed in which focus detection is performed at a predetermined cycle while moving the focus lens 104 to search for the in-focus position of the focus lens 104. Then, the focus lens 104 is moved to the in-focus position identified by the search.

[0069] In step S801, the camera MPU 125 determines the lens drive direction for the search operation. In this embodiment, the lens drive direction for the search operation is determined based on the rotation direction of the rotary operation unit 105 acquired in step S1401. The relationship between the rotation direction of the rotary operation unit 105 and the direction of advance / retract drive of the focus lens 104 is set to match when the manual focus (MF) function is assigned to the rotary operation unit 105 and when the search AF function is assigned to the rotary operation unit 105. As an example, a case will be described in which the manual focus (MF) function is assigned to the rotary operation unit 105, and the focus position is moved toward infinity when the rotary operation unit 105 is rotated left, and the focus position is moved toward a closer point when the rotary operation unit 105 is rotated right. In the above setting state, when the search AF function is assigned to the rotary operation unit 105, the search direction is determined so that search drive is started in a direction that moves the focus position toward infinity when the rotary operation unit 105 is rotated left. Furthermore, the search direction is determined so that when the rotary operation unit 105 is rotated clockwise, search drive is started in a direction that moves the focus position toward the closest point. In this embodiment, the relationship between the rotary operation unit 105 and the forward / backward drive direction of the focus lens 104 has been described as an example, but the above-described relationship can also be reversed by user settings.

[0070] In step S802, the camera MPU 125 acquires the current position of the focus lens 104 from the lens MPU 117.

[0071] In step S803, camera MPU 125 calculates the driveable range of focus lens 104 (hereinafter referred to as the focus driveable range). The calculation of the focus driveable range will be described later.

[0072] In step S804, the camera MPU 125 determines whether the focus detection result (defocus amount in this embodiment) acquired in step S701 or step S809 described later is within the focus driveable range calculated in step S803. If it is determined that the focus detection result is within the focus driveable range, the process proceeds to step S805, and if it is determined that it is not within the focus driveable range, the process proceeds to step S806. Here, if the reliability of the focus detection result is low and there is no usable focus detection result, it is determined that it is not within the focus driveable range.

[0073] In step S805, the camera MPU 125 sets the driving amount of the focus lens 104 based on the focus detection result acquired in step S701 or step S809, which will be described later.

[0074] In step S806, camera MPU 125 determines the drive speed of the focus lens for the search operation without using the focus detection results acquired in step S701 or step S809 (described later). The drive speed of the focus lens is determined based on information about the rotation speed of rotary operation unit 105 calculated by lens MPU 117 and a correspondence table between rotation speed and lens drive speed stored in advance in ROM 125a. The correspondence table sets the drive speed of the focus lens to be fast when the rotation speed of rotary operation unit 105 is fast and to be slow when the rotation speed is slow.

[0075] In the following step S807, the camera MPU 125 sets the drive speed of the focus lens determined in step S806.

[0076] In step S808, the camera MPU 125 drives the focus lens. If the focus lens drive amount was set in step S805, the lens is driven stepwise according to the set drive amount. On the other hand, if the focus lens drive speed was set in step S807, the lens is driven to perform search according to the set drive speed.

[0077] In step S809, the camera MPU 125 controls the phase difference AF unit 129 to determine whether the focus is achieved or for subsequent lens driving, and acquires the focus detection result.

[0078] In step S810, the camera MPU 125 determines whether or not the focus is achieved. If it is determined that the focus is achieved, the search AF operation ends. If it is determined that the focus is not achieved, the process proceeds to step S811.

[0079] In step S811, the camera MPU 125 determines whether or not the rotation operation unit 105 has been rotated based on the amount of operation of the rotation operation unit 105 notified by the lens MPU 117 in response to a request from the camera MPU 125. If the rotation operation has been performed during search AF, the process proceeds to step S812; if the rotation operation has not been performed, the process proceeds to step S814.

[0080] In step S812, the camera MPU 125 executes a search AF execution determination similar to that in step S705, and then proceeds to step S814.

[0081] In step S814, the camera MPU 125 determines whether or not a re-search instruction has been issued during search AF. If a re-search instruction has been issued, the process returns to step S801, the search direction is determined again, and search AF continues. If a re-search instruction has not been issued, the process returns to step S802, and search AF continues.

[0082] If it is determined in step S810 that the focus is achieved, the search AF process ends.

[0083] <Calculation of focus driving range> The calculation of the focus drivable range in step S803 of Fig. 8 will be described. Fig. 10 shows the positional relationship between the subject and the background. The subject is located close to the imaging system 10, and the background is located sufficiently far from the imaging system 10.

[0084] 11(a) and (b) show a signal indicating the subject (hereinafter referred to as the subject signal) and a signal indicating the background (hereinafter referred to as the background signal) acquired from the image sensor 122 when the subject and background are in the positional relationship shown in Fig. 10. Fig. 11(a) shows a subject signal 1102 and a background signal 1101 when the image sensor is focused on the background. Fig. 11(b) shows a subject signal 1104 and a background signal 1103 when the image sensor is focused on the subject. In reality, the subject signal and the background signal are acquired from the image sensor 122 as a signal obtained by adding these together, but here the subject signal and the background signal are shown separately.

[0085] In the background-focused state of FIG. 11(a), the contrast of the background signal 1101 is high and the contrast of the object signal 1102 is very low. Therefore, the background-focused state is heavily influenced by the background signal 1101, and the amount of defocus relative to the background is detected as the focus detection result. On the other hand, in the object-focused state of FIG. 11(b), the contrast of the object signal 1104 is high and the contrast of the background signal 1103 is very low. Therefore, the object-focused state is heavily influenced by the object signal 1104, and the amount of defocus relative to the object is detected as the focus detection result.

[0086] Figure 12 shows the relationship between the focus lens position and the focus detection result when the subject and background are positioned as shown in Figure 10. The horizontal axis represents the focus lens position, and the vertical axis represents the defocus amount. The search direction is from the side with the longest focusing distance (background) to the side with the shortest focusing distance (subject).

[0087] When the focus lens position is near the background in-focus position (1201, 1202), the defocus amount for the background is detected under the significant influence of the background signal, as described above. On the other hand, when the focus lens position is near the subject in-focus position (1203, 1204), the defocus amount for the subject is detected under the significant influence of the subject signal. In the section between the vicinity of the background in-focus position and the vicinity of the subject in-focus position, the contrast of both the background signal and the subject signal is low, so the reliability of the defocus amount is low and it is not possible to detect a defocus amount that can be used for AF.

[0088] 9 shows the process of calculating the focus drivable range executed by the camera MPU 125. In step S901, a difference x between the search start position of the focus lens 104 acquired in step S802 at the start of search AF (search start) and the current position of the focus lens 104 acquired in step S802 in the current frame is calculated.

[0089] Next, in step S902, it is determined whether the difference x is equal to or less than a predetermined first threshold Th1. If it is equal to or less than the first threshold Th1, the process proceeds to step S903, and if it is not equal to or less than the first threshold Th1, the process proceeds to step S905.

[0090] In step S903, the focus detectable range of the phase difference AF unit 129 is acquired, and further the currently set aperture value and focus sensitivity (optical information of the imaging optical system) are acquired from the lens MPU 117. The focus detectable range is the amount of image blur (amount of spread of the subject image) that can be detected by the phase difference AF unit 129. The focus sensitivity indicates the relationship (ratio) between the unit drive amount of the focus lens 104 and the amount of change in the defocus amount.

[0091] Next, in step S904, an offset amount in the same direction as the search direction obtained in step S801 is calculated based on the difference x calculated in step S901 and the focus detectable range R, aperture value F, and focus sensitivity S obtained in step S903. The offset amount is the drive amount of the focus lens 104 calculated taking into account the case where the search start position is in the opposite direction to the search direction from the background in-focus position, and is calculated, for example, using the following equation (1): α is a predetermined gain value.

[0092] Offset amount = α(R / x)FS If an image blur that exceeds the focus detectable range occurs for a subject near the search start position, focus detection results for that subject cannot be obtained, so there is no need to set an offset amount that will cause an image blur that exceeds the focus detectable range.For this reason, in such cases, the offset amount is set based on the focus detectable range.

[0093] Furthermore, as the current position of the focus lens 104 moves away from the search start position, the possibility that the current position will exceed the background in-focus position increases. For this reason, the offset amount is reduced as the current position moves away from the search start position, so that it is inversely proportional to the difference x between the search start position and the current position, thereby preventing an offset amount from being set that is too large. Note that the aperture value F is used to convert the image blur amount to the defocus amount, and the focus sensitivity is used to convert the defocus amount to the focus drive amount. Note that equation (1) is an example of an equation for calculating the offset amount, and the offset amount may be calculated using other methods. From step S904, the process proceeds to step S909.

[0094] In step S909, the focus driveable range is calculated based on the current position of the focus lens 104, the offset amount calculated in step S904, and the search direction acquired in step S801. The focus driveable range is the range from a position shifted (away) from the current position in the search direction by the offset amount to the drive end (control end or mechanical end) of the focus lens 104 in the search direction. Having calculated the focus driveable range, the camera MPU 125 ends this process.

[0095] 13(a) to 13(d) show the relationship between the search direction, search start position, focus lens position, focus driveable range, defocus amount, and focus drive amount in this embodiment. Note that focus positions (current positions) 1201 to 1204 in the figures correspond to the positions 1201 to 1204 shown in FIG.

[0096] FIG. 13A shows the state at the start of a search, with the focus lens 104 located at the search start position as the current position 1201. In this state, x (= 0)≦Th1, so an offset amount 1302a is set in the same direction as the search direction based on the focus detectable range, the aperture value, the focus sensitivity, and x (step S904). A focus drivable range 1303a is set in the search direction from a position shifted in the search direction from the search start position by the offset amount 1302a. In this state, a defocus amount 1301a to the background in-focus position is detected. However, the background in-focus position as the target position of the focus lens 104 based on the defocus amount 1301a falls outside the focus drivable range 1303a. Therefore, the defocus amount 1301a is not used, and the lens is search-driven according to the drive speed set in S807.

[0097] In this way, a focus driveable range is set that is shifted in the search direction from the search start position (current position) by the offset amount. This makes it possible to search for the subject focus position without focusing on the background, even if the search start position is in the opposite search direction from the background focus position.

[0098] FIG. 13B shows a state in which the focus lens has moved from the search start position to a current position 1202, which is closer to the subject-focused position than the background-focused position. Because x (>0)≦Th1 holds even in this state, an offset amount 1302b is set in the same direction as the search direction based on the focus detectable range, the aperture value, the focus sensitivity, and x (step S904). A focus-drivable range 1303b is set in the search direction from a position shifted by the offset amount 1302b from the current position 1202. Because x is larger than in the state of FIG. 13A, the offset amount 1302b is smaller than the offset amount 1302a. Even in this state, a defocus amount 1301b to the background-focused position is detected. However, the background-focused position as the target position of the focus lens 104 based on the defocus amount 1301b falls outside the focus-drivable range 1303b. Therefore, the defocus amount 1301b is not used, and the lens is driven to perform a search at the drive speed set in S807. The focus drive amount 1304b is the same as the focus drive amount 1304a shown in FIG. 13(a), but may be different, for example, made smaller.

[0099] In this way, a focus driveable range is set that is shifted by the offset amount from the focus lens position after the search starts. This makes it possible to search for the subject in-focus position without focusing on the background, even if the detected defocus amount 1301a is for a position within the focus driveable range (1303a) set at the start of the search.

[0100] In step S905 of FIG. 9, the camera MPU 125 determines whether the difference x is equal to or greater than a predetermined second threshold Th2 (>Th1), and if it is equal to or greater than the threshold Th2, proceeds to step S906, and if it is not equal to or greater than the threshold Th2, proceeds to step S908.

[0101] In step S906, the camera MPU 125 acquires the drive speed of the focus lens 104 and the focus detection cycle.

[0102] Next, in step S907, the camera MPU 125 calculates an offset amount in the opposite direction to the search direction obtained in step S801, based on the drive speed and focus detection cycle obtained in step S906, and further based on the difference x calculated in step S901. The offset amount here is set taking into consideration the case where the subject in-focus position is overshot during search due to the relationship between the drive speed v of the focus lens 104 and the focus detection cycle T, and is calculated, for example, using the following equation (2): β is a predetermined gain value.

[0103] Offset amount = βvTx The drive amount of the focus lens 104 between frames in which focus detection is performed is calculated by the product of the drive speed v and the focus detection period T. Because the drive amount of the focus lens 104 between frames represents the maximum amount by which the focus lens 104 overshoots the subject in-focus position, the offset amount is set based on this drive amount. Furthermore, the farther away from the search start position is, the higher the likelihood that the focus lens 104 will overshoot the subject in-focus position. Therefore, by increasing the offset amount in proportion to the difference x between the search start position and the current position of the focus lens 104, it becomes easier to capture the subject in-focus position within the driveable range even in the event of an overshoot. That is, since the possibility of overshooting is low at the start of the search, the range is narrowed to reduce the risk of returning to the background. Then, since the risk of returning to the background decreases and the risk of overshooting increases as the focus lens moves away from the start position, the driveable range is expanded in the search start direction. This makes it easier to bring the subject in-focus position within the driveable range even in the event of an overshoot. The above calculation method for the offset amount is merely an example, and other methods may be used. For example, the offset amount (that is, the focus drivable range) may be set based on only one of the drive speed of the focus lens 104 and the focus detection cycle.

[0104] On the other hand, in step S908, the camera MPU 125 sets the offset amount to 0. Then, the process proceeds to step S909, where the focus drivable range is calculated as described above, and the process ends.

[0105] FIG. 13(c) shows a state in which the focus lens 104 has moved to a current position 1203, which is closer to the subject in-focus position than the state in FIG. 13(b). In this state, x≧Th2, so an offset amount 1302c is set in the direction opposite to the search direction based on the drive speed of the focus lens 104, the focus detection cycle, and the difference x (step S907). A focus drivable range 1303c is set in the search direction from a position shifted by the offset amount 1302c in the direction opposite to the search direction from the current position 1203. In this state, a defocus amount 1301c to the subject in-focus position is detected, and the subject in-focus position as the target position of the focus lens 104 based on the defocus amount 1301c falls within the focus drivable range 1303c. Therefore, a focus drive amount 1304c is set based on the defocus amount 1301c (step S805).

[0106] In this way, the focus driveable range is set in the search direction from a position that is shifted by the offset amount in the opposite direction to the search direction from the current position of the focus lens 104. This makes it possible to drive the focus lens 104 to focus on the subject based on the defocus amount detected at the timing when the subject in-focus position falls within the focus driveable range.

[0107] FIG. 13(d) shows a state in which the focus lens 104 has moved to a current position 1204, past the subject in-focus position. Since x≧Th2 holds even in this state, an offset amount 1302d is set in the direction opposite to the search direction based on the drive speed of the focus lens 104, the focus detection cycle, and the difference x (step S907). A focus driveable range 1303d is set in the search direction from a position shifted by the offset amount 1302d in the direction opposite to the search direction from the current position 1204. Because the difference x is larger than in the state of FIG. 13(c), the offset amount 1302d is larger than the offset amount 1302c. In this state, a defocus amount 1301d to the subject in-focus position located in the direction opposite to the search direction is detected, and the subject in-focus position as the target position of the focus lens 104 based on the defocus amount 1301d falls within the focus driveable range 1303d. Therefore, a focus drive amount 1304d is set based on the defocus amount 1301d.

[0108] In this way, the focus driveable range is set in the search direction from a position that is shifted by the offset amount in the opposite direction to the search direction from the current position of the focus lens 104. This makes it possible to drive the focus lens 104 based on the defocus amount to bring the subject into focus, even if the focus lens 104 passes the subject in-focus position in the search direction.

[0109] As described above, in this embodiment, the focus driveable range is set from a position that is shifted by the offset amount from the current position of the focus lens 104. Then, the focus drive amount is set depending on whether or not a focus detection result has been obtained for a position within the focus driveable range. This allows appropriate search AF to be performed for the subject desired by the user, and a focused state for the subject can be quickly obtained.

[0110] <Method of setting the function to be assigned to the ring member (rotation operation unit 105) on the outer periphery of the lens barrel> So far, we have described in detail the search AF that is unique to this embodiment, including the operation flow. Next, we will explain how to set the search AF function.

[0111] FIG. 15 shows an example of a setting screen displayed on the display 126 when assigning a function to the rotary operation unit 133. The user selects the "Lens Electronic Focus Ring Function" menu from the camera's setting menu screen to transition to the setting screen. In this embodiment, the rotary operation unit 105 is configured with a menu limited to focus lens operation functions in advance, but other functions mentioned above may also be assignable. In this setting menu, "Not Used" is selected if the function assigned to the rotary operation unit 105 is not to be used; "Manual Focus (MF)" is selected if the manual focus (MF) function is to be assigned; and "Search AF" is selected if the search AF function is to be assigned. This embodiment is described assuming that there is a single ring member arranged on the outer periphery of the lens barrel. Therefore, "Manual Focus (MF)" and "Search AF," which operate in conflict with each other, are described as being exclusively settable. In this embodiment, the control function of "Search AF" is assigned to the rotary operation unit 105.

[0112] <Display screen when performing search AF> Next, an example of the display screen of the display 126 when search AF is being performed is shown in FIG.

[0113] In FIG. 16, 1801 is an example of displaying an AF frame, 1802 is an example of displaying an item indicating the position of the lens distance ring, and 1803 is an example of displaying an item indicating the implementation status of search AF. It is desirable for 1803 to be a system in which whether search AF is set or not, and the lens drive direction and drive speed for the search operation are indicated by icons displayed on the rear LCD monitor. As an example, in this embodiment, as shown in FIG. 16, the drive direction and drive speed for the search operation are displayed in association with the direction and number of arrows. Note that the implementation status of search AF may simply indicate whether or not a search operation is in progress.

[0114] The display screen in this embodiment makes it possible to prevent erroneous operation by the user and to quickly reset the lens when the lens is driven in an unintended state by the user.

[0115] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that realizes one or more functions. The above-described embodiments are merely representative examples, and various modifications and changes to each embodiment are possible when implementing the present invention.

[0116] The above embodiment includes the following configurations.

[0117] (Configuration 1) a focus detection means for performing focus detection; a control unit that controls the driving of a focus lens included in the optical system based on a focus detection result obtained by the focus detection, The control means controls the relationship between the rotation direction of a ring member that can be rotated by a user and the drive direction of the focus lens, and the relationship between the rotation direction of the ring member and the search direction so that they correspond to each other, and starts a search operation that performs focus detection at a predetermined cycle while moving the focus lens in accordance with the amount of rotation of the ring member.

[0118] (Configuration 2) 2. The focus control device according to configuration 1, wherein the control means does not start a search operation of the focus lens when the amount of rotation of the ring member is smaller than a predetermined amount.

[0119] (Configuration 3) 2. The focus control device according to configuration 1, wherein the control means does not start a search operation of the focus lens when the rotation speed of the ring member is slower than a predetermined speed.

[0120] (Configuration 4) 2. The focus control device according to configuration 1, wherein the control means determines a drive speed of the focus lens in accordance with a rotation speed of the ring member.

[0121] (Configuration 5) The focus control device described in configuration 1 is characterized in that the control means performs a first search operation that starts a search operation in accordance with the amount of rotation of the ring member, and starts a second search operation in accordance with the amount of rotation of the ring member when the ring member is operated during the first search operation or after the first search operation.

[0122] (Configuration 6) The focus control device described in configuration 5 is characterized in that, when the rotation direction of the ring member is opposite in the first search operation and the second search operation, the control means sets the drive speed of the focus lens in the second search operation to be slower than the drive speed of the focus lens in the first search operation.

[0123] (Configuration 7) Further, the camera has a receiving unit for receiving a manual focus operation, 2. The focus control device according to configuration 1, wherein the control means does not start a search operation of the focus lens when the manual focus operation is accepted.

[0124] (Configuration 8) 2. The focus control device according to configuration 1, further comprising display control means for controlling the display means to display an item that indicates the implementation status of the search operation.

[0125] (Configuration 9) 2. The focus control device according to configuration 1, further comprising a display control means for controlling a display means to display an item indicating the position of the distance ring of the focus lens.

[0126] (Configuration 10) A focus control device according to any one of configurations 1 to 9; an imaging element that captures an image of a subject through the optical system.

[0127] (Method 1) a focus detection step for performing focus detection; a control step of controlling the driving of a focus lens included in the optical system based on a focus detection result obtained by the focus detection, The control step controls the relationship between the rotation direction of a ring member that can be rotated by the user and the drive direction of the focus lens, and the relationship between the rotation direction of the ring member and the search direction so that they correspond to each other, and a search operation is started that performs focus detection at a predetermined cycle while moving the focus lens in accordance with the amount of rotation of the ring member.

[0128] (Program 1) A program for causing a computer to function as each of the means possessed by the focus control device according to any one of configurations 1 to 9. [Explanation of symbols]

[0129] 100 Lens Unit 104 Focus Lens 120 Camera body 125 Camera MPU 129 Phase difference AF section

Claims

1. a focus detection means for performing focus detection; a control unit that controls the driving of a focus lens included in the optical system based on a focus detection result obtained by the focus detection, The control means controls the relationship between the rotation direction of a ring member that can be rotated by a user and the drive direction of the focus lens, and the relationship between the rotation direction of the ring member and the search direction so that they correspond to each other, and starts a search operation that performs focus detection at a predetermined cycle while moving the focus lens in accordance with the amount of rotation of the ring member.

2. 2. The focus control device according to claim 1, wherein the control means does not start the search operation of the focus lens when the amount of rotation of the ring member is smaller than a predetermined amount.

3. 2. The focus control device according to claim 1, wherein the control means does not start the search operation of the focus lens when the rotation speed of the ring member is slower than a predetermined speed.

4. 2. The focus control device according to claim 1, wherein the control means determines a drive speed of the focus lens in accordance with a rotation speed of the ring member.

5. 2. The focus control device according to claim 1, wherein the control means performs a first search operation in response to the amount of rotation of the ring member, and a second search operation in response to the amount of rotation of the ring member when the ring member is operated during the first search operation or after the first search operation.

6. 6. The focus control device according to claim 5, wherein the control means sets the drive speed of the focus lens in the second search operation to be slower than the drive speed of the focus lens in the first search operation when the rotation direction of the ring member is opposite to that in the first search operation and the second search operation.

7. Further, the camera has a receiving unit for receiving a manual focus operation, 2. The focus control device according to claim 1, wherein the control means does not start a search operation of the focus lens when the manual focus operation is accepted.

8. 2. The focus control device according to claim 1, further comprising a display control means for controlling the display means to display an item that indicates the implementation status of the search operation.

9. 2. The focus control device according to claim 1, further comprising a display control unit that controls a display unit to display an item indicating the position of the distance ring of the focus lens.

10. A focus control device according to any one of claims 1 to 9; an imaging element that captures an image of a subject through the optical system.

11. a focus detection step for performing focus detection; a control step of controlling the driving of a focus lens included in the optical system based on a focus detection result obtained by the focus detection, The control step controls the relationship between the rotation direction of a ring member that can be rotated by the user and the drive direction of the focus lens, and the relationship between the rotation direction of the ring member and the search direction so that they correspond to each other, and a search operation is started that performs focus detection at a predetermined cycle while moving the focus lens in accordance with the amount of rotation of the ring member.

12. A program for causing a computer to function as each of the means included in the focus control device according to any one of claims 1 to 9.

Images