JP2015049251A - Imaging device and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which when photographing a moving subject and the like, it takes much time for a photographing lens to move to a focus position, and thus, there have been cases where shooting timing is missed.SOLUTION: An imaging device according to a first embodiment comprises: a setting part that sets a control parameter about focus accuracy; and a control part that controls a movement speed of a focus lens on the basis of the setting by the setting part. A control program according to a second embodiment causes a computer to execute: a setting step of setting the control parameter about the focus accuracy; and a control step of controlling the movement speed of the focus lens on the basis of the setting.

Description

  The present invention relates to an imaging apparatus and a control program.

A lens drive control device that includes a position table in which a position locus value is set so that the defocus amount decreases with time and drives the photographing lens to a focus position along the position locus value indicated by the position table is known. (For example, refer to Patent Document 1).
[Prior art documents]
[Patent Literature]
[Patent Document 1] JP 2012-208138 A

  When shooting a moving subject, it takes time for the photographic lens to move to the in-focus position, and the shooting timing may be missed.

  The imaging device according to the first aspect of the present invention includes a setting unit that sets a control parameter related to focus accuracy, and a control unit that controls the moving speed of the focus lens based on the setting by the setting unit.

  The control program according to the second aspect of the present invention causes a computer to execute a setting step for setting a control parameter relating to focus accuracy and a control step for controlling the moving speed of the focus lens based on the setting.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a figure explaining the structure of the digital camera which concerns on this embodiment. It is a figure explaining a high accuracy mode and a low accuracy mode. It is a figure explaining the case where either high accuracy mode or low accuracy mode is selected automatically. It is a figure explaining the case where the focus lens 212 is made to focus and track with respect to the to-be-photographed object moving at a fixed speed. It is a figure explaining the example of a display of the selection screen in autofocus mode. It is a flowchart which shows an example of the process which concerns on imaging | photography operation | movement in auto selection mode.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a diagram illustrating a configuration of a digital camera 100 according to the present embodiment. The digital camera 100 is configured by mounting an interchangeable lens 200 on a camera body 300. The interchangeable lens 200 includes a photographing lens 210 as a photographing optical system, an interchangeable lens control unit 220, a system memory 230, a zoom lens driving unit 240, and a focus lens driving unit 250. The camera body 300 includes a main mirror 301, a sub mirror 302, a focus plate 303, a pentaprism 304, an eyepiece optical system 305, a finder window 306, an AF sensor 307, an image sensor 308, an A / D converter 309, an internal memory 310, and image processing. A unit 311, a recording medium IF 312, a display control unit 313, a display unit 314, an operation member 315, a release switch 316, a system memory 317, and a camera body control unit 318.

  The interchangeable lens 200 includes a lens mount 260, and the camera body 300 includes a camera mount 360. When the lens mount 260 and the camera mount 360 are engaged, the connection between the communication terminal on the interchangeable lens 200 side and the communication terminal on the camera body 300 side is established. Thereby, the interchangeable lens control unit 220 and the camera body control unit 318 can communicate a control signal and the like with each other. The interchangeable lens control unit 220 and the camera body control unit 318 cooperate with each other while performing communication to control the interchangeable lens 200 and the camera body 300.

  There are a plurality of types of interchangeable lenses 200 having different optical characteristics. The user can attach any one to the camera body 300. The taking lens 210 provided in the interchangeable lens 200 includes a plurality of optical lens groups. Specifically, the taking lens 210 includes a zoom lens 211 and a focus lens 212. The photographic lens 210 guides the subject luminous flux incident along the optical axis 201 to the image sensor 308 disposed in the camera body 300.

  By rotating around the rotation axis, the main mirror 301 can take a state of being obliquely provided in the subject light flux centered on the optical axis 201 and a state of being retracted from the subject light flux. The main mirror 301 is obliquely provided in the subject luminous flux when the subject image is guided to the focus plate 303 side. The main mirror 301 in the inclined state reflects the subject image incident from the photographing lens 210 toward the focus plate 303 side. The focus plate 303 is disposed at a position conjugate with the light receiving surface of the image sensor 308. A subject image reflected by the main mirror 301 is formed on the focus plate 303. The subject image formed on the focusing screen 303 is converted into an erect image by the pentaprism 304 and is observed by the user from the viewfinder window 306 via the eyepiece optical system 305. A region in the vicinity of the optical axis 201 of the main mirror 301 in an oblique state is formed as a half mirror and transmits a part of the incident light beam. The transmitted light beam is reflected by the sub mirror 302 that operates in conjunction with the main mirror 301 and enters the AF sensor 307. The sub mirror 302 retracts from the subject light beam in conjunction with the main mirror 301 in a state where the main mirror 301 is retracted.

  A part of the subject light beam incident through the optical system is guided to the AF sensor 307 by the sub mirror 302. The AF sensor 307 includes a plurality of photoelectric conversion element arrays that receive a part of the subject light beam guided from the sub mirror 302. The AF sensor 307 outputs a signal with a phase match when in the in-focus state, and outputs a signal with a phase shift when in the front pin state or the rear pin state. The amount of phase shift corresponds to the amount of shift from the focus state. The AF sensor 307 detects a phase difference by performing a correlation operation on the output of the photoelectric conversion element array, and outputs a phase difference signal indicating the phase difference to the camera body control unit 318. Further, the AF sensor 307 is configured to be able to detect the defocus amount from the in-focus position in the defocus state. The camera body control unit 318 outputs a control signal for moving the focus lens 212 to the target position to the interchangeable lens control unit 220.

  The imaging element 308 is an element that photoelectrically converts an optical image that is a subject image. A CCD sensor or a CMOS sensor can be used as the image sensor 308. The subject image photoelectrically converted by the image sensor 308 is converted from an analog signal to a digital signal by an A / D converter 309.

  The subject image converted into the digital signal is sequentially processed as image data. The image data is temporarily stored in the internal memory 310. The internal memory 310 is a random access memory that can be read and written at high speed. A DRAM or SRAM can be used as the internal memory 310. The internal memory 310 plays a role as a work memory in the image processing and compression processing performed by the image processing unit 311. The internal memory 310 has a sufficient memory capacity corresponding to this role.

  The image processing unit 311 converts the image data into image data according to a predetermined image format in accordance with the set shooting mode and an instruction from the user. When a JPEG file is generated as a still image, image processing such as color conversion processing, gamma processing, and white balance processing is performed, and then adaptive discrete cosine conversion is performed to perform compression processing. When an MPEG file is generated as a moving image, intra-frame encoding and inter-frame encoding are performed on a frame image as a continuous still image generated by being reduced to a predetermined number of pixels, and compression processing is performed. . The converted image data is stored in the internal memory 310 again.

  Still image data and moving image data processed by the image processing unit 311 are recorded from the internal memory 310 to the recording medium 400 via the recording medium IF 312. The recording medium 400 is a non-volatile memory that is configured with a flash memory or the like and is detachable from the camera body 300. The image processing unit 311 generates display image data in parallel with the image data processed for recording. The generated display image data is displayed on the display unit 314 according to the control of the display control unit 313. Regardless of the presence or absence of recording, if the camera body control unit 318 causes the image processing unit 311 to generate image data for sequential display and display it on the display unit 314, a live view as an electronic viewfinder function can be realized. In addition, a setting screen for various settings can be displayed on the display unit 314.

  The camera body 300 is controlled directly or indirectly by the camera body control unit 318 including each element in the image processing described above. The camera body control unit 318 communicates with the system memory 317. The system memory 317 is an electrically erasable / recordable nonvolatile memory, and is configured by, for example, an EEPROM (registered trademark). The system memory 317 records constants, variables, programs, and the like necessary when the digital camera 100 is operating so that they are not lost even when the digital camera 100 is not operating. As the program, for example, a program for executing processing related to a photographing operation in an auto selection mode described later is recorded. Moreover, the switching determination time mentioned later is memorize | stored. The camera body control unit 318 expands constants, variables, programs, and the like in the internal memory 310 as appropriate and uses them for controlling the digital camera 100.

  The zoom lens 211 is driven by the zoom lens driving unit 240 under the overall control of the camera body control unit 318 and the interchangeable lens control unit 220. The zoom lens driving unit 240 drives the zoom lens 211 according to a user instruction to change the angle of view.

  The focus lens 212 is driven by the focus lens driving unit 250 under the overall control of the camera body control unit 318 and the interchangeable lens control unit 220. The focus lens driving unit 250 drives the focus lens 212 so that a subject image in a specific area is focused on the light receiving surface of the image sensor 308 according to information from the AF sensor 307. The focus lens driving unit 250 includes a drive motor 251 for driving the focus lens 212 and an encoder 252 for detecting the position of the focus lens 212. Information indicating the position of the focus lens 212 detected by the encoder 252 is sent to the camera body control unit 318 via the interchangeable lens control unit 220.

  The system memory 230 stores a drive control table used for drive control of the focus lens 212. The drive control table is set for each divided range that is a range obtained by dividing the drive range of the focus lens 212 into a plurality of ranges. The drive control table defines the control parameters of the focus lens 212 and the allowable range of deviation of the focus lens 212 from the target position. As a control parameter used for driving control of the focus lens 212, the target speed of the focus lens 212 can be used. The target speed of the focus lens 212 is set to be different for each segment range of the focus lens 212. The allowable range and the target speed are set to be different in each of the high-accuracy mode and the low-accuracy mode to be described later in each segment range of the focus lens 212. Further, the system memory 230 stores a determination table used when the auto selection mode, which will be described later, is set, for each segment range of the focus lens 212. The determination table is, for example, a table showing a relationship between the defocus amount and time in each of the high accuracy mode and the low accuracy mode, that is, a characteristic curve described later.

  When communication with the camera main body control unit 318 is established, the interchangeable lens control unit 220 transmits a drive control table and a determination table to the camera main body control unit 318. Accordingly, the camera body control unit 318 can acquire a drive control table and a determination table according to the optical characteristics of the attached interchangeable lens 200.

  The digital camera 100 includes a plurality of operation members 315 that receive operations from the user. The camera body control unit 318 detects that these operation members 315 are operated, and executes an operation corresponding to the operation. For example, the control parameter of the focus lens 212 and the allowable range of deviation of the focus lens 212 with respect to the target position are set in accordance with the auto focus mode described later. The operation member 315 is used for various settings related to the digital camera 100. The operation member 315 is used for setting a focus mode, for example. The user can set the auto focus mode or the manual focus mode by operating the operation member 315. In the present embodiment, the autofocus mode includes a high accuracy mode, a low accuracy mode, and an auto selection mode. The high-accuracy mode is a mode that allows a first error range as an allowable range with respect to the target position of the focus lens 212. The low accuracy mode is a mode that allows a second error range that is larger than the first error range as an allowable range. The auto selection mode is a mode that is automatically set to either the high accuracy mode or the low accuracy mode by the camera body control unit 318.

  In the high accuracy mode, the driving speed of the focus lens 212 is allowed up to the first speed. In the low accuracy mode, the driving speed of the focus lens 212 is allowed up to a second speed larger than the first speed. When the high accuracy mode and the low accuracy mode are compared, in the high accuracy mode, the focusing accuracy is higher than in the low accuracy mode, but the rising response is low. The user can set any of the high accuracy mode, the low accuracy mode, and the auto selection mode by operating the operation member 315. The user can select a control parameter for the moving speed of the focus lens 212 and an allowable range of deviation from the target position of the focus lens 212 through mode selection. The operation member 315 may include a focus accuracy changeover switch as a switch for setting any one of the high accuracy mode, the low accuracy mode, and the auto selection mode.

  In actual shooting, it may be desired to prioritize AF speed over strict focusing accuracy. In particular, when shooting a moving subject, it is preferable to drive the focus lens 212 earlier than to drive the focus lens 212 over time and increase the focusing accuracy. If the focus lens 212 is driven earlier, the defocus amount is reduced, and as a result, blurring of the image can be suppressed. Therefore, when shooting a moving subject, the low accuracy mode may be set.

  The operation member 315 is used for setting the AF servo mode when the auto focus mode is set. The user can set the focus priority single AF servo (AF-S) or the release priority continuous AF servo (AF-C) by operating the operation member 315.

  The digital camera 100 includes a release switch 316 as a kind of operation member 315. The release switch 316 includes a push button that can be detected in two steps in the pressing direction. The camera main body control unit 318 executes AF or the like as a shooting preparation operation by detecting SW1 that is the first-stage depression, and acquires the subject image by the image sensor 308 by detecting SW2 that is the second-stage depression. Perform the action.

  FIG. 2 is a diagram illustrating the high accuracy mode and the low accuracy mode. FIG. 2A is a diagram illustrating the movement of the focus lens 212. In particular, the movement of the focus lens 212 from the current position to the in-focus range when the defocus amount is D1 is shown. In FIG. 2A, the horizontal axis indicates time, and the vertical axis indicates the defocus amount of the focus lens 212. A solid line indicates the characteristic curve 101 when the high accuracy mode is set, and a broken line indicates the characteristic curve 102 when the low accuracy mode is set. FIG. 2B shows control parameters for obtaining each characteristic curve shown in FIG. In particular, the case where the target speed is used as the control parameter is shown. In FIG. 2B, the horizontal axis represents time, and the vertical axis represents the target speed when the focus lens 212 is driven. The solid line shows the trajectory of the target speed for obtaining the characteristic curve 101, and the broken line shows the trajectory of the target speed for obtaining the characteristic curve 102.

  First, the high accuracy mode will be described. In the high-accuracy mode, control parameters are set so that the focus lens 212 can move smoothly and stop within the in-focus range in consideration of the drive characteristics of the drive motor 251, the operating environment, and the like. More specifically, a target speed gradient 111 during acceleration, a target maximum speed Max_a, and a target speed gradient 112 during deceleration are set as control parameters. Further, a focusing range 103 as a first error range is set according to these control parameters. In the high accuracy mode, control is performed so that the focus lens 212 is within the focusing range 103 that is narrower than the focusing range in the low accuracy mode described later. Therefore, the target speed gradient 111 during acceleration and the target speed gradient 112 during deceleration are set more gently than the target speed gradient during acceleration and the target speed gradient during deceleration in the low accuracy mode. The target maximum speed Max_a is also set slower than the target maximum speed in the low accuracy mode.

  The camera body control unit 318 starts drive control for the drive motor 251 at time t0, which is the time when SW1 is detected. Thereby, drive control of the focus lens 212 interlocked with the drive motor 251 is also started. The camera body control unit 318 performs feedback control using the target speed gradient 111 during acceleration when the drive motor 251 is started. When the speed of the drive motor 251 reaches the target maximum speed Max_a at time t3, the camera body control unit 318 maintains the target maximum speed Max_a for a certain period, specifically, until time t4. To control. When time t4 is reached, feedback control is performed using the target speed gradient 112 during deceleration. Time t4 is a time at which the remaining defocus amount up to the target position is equal to or less than a predetermined value. Time t4 is set in advance through experiments, simulations, and the like. When the remaining defocus amount reaches the in-focus range 103 at time t <b> 6, the camera body control unit 318 stops the drive motor 251.

  Next, the low accuracy mode will be described. In the low-accuracy mode, the control parameters are set with emphasis on the response of the drive motor 251 to rise. More specifically, the target speed gradient 113 during acceleration, the target maximum speed Max_b, and the target speed gradient 114 during deceleration are set as control parameters. Further, a focusing range 104 as a second error range is set according to these control parameters. In the low accuracy mode, the target speed gradient 113 during acceleration and the target speed gradient 114 during deceleration change more rapidly than in the high accuracy mode. Further, the target maximum speed Max_b is faster than the target maximum speed Max_a. On the other hand, as shown in FIG. 2A, the stop position of the focus lens 212 may be outside the focus range 103 in the high accuracy mode. Therefore, the focusing range 104 in the low accuracy mode is wider than the focusing range 103. Thus, in the low accuracy mode, the focusing accuracy is looser than in the high accuracy mode. In other words, it can be said that the range in which the release is permitted is widened.

  The camera body control unit 318 starts drive control for the drive motor 251 at time t0. Thereby, drive control of the focus lens 212 interlocked with the drive motor 251 is also started. When the drive motor 251 is started, the camera body control unit 318 performs feedback control using the target speed gradient 113 during acceleration. When the speed of the drive motor 251 reaches the target maximum speed Max_b at time t1 earlier than time t3, the camera body control unit 318 maintains the target maximum speed Max_b for a certain period, specifically until time t2. Thus, the drive motor 251 is controlled. When time t2 is reached, feedback control is performed using the target speed gradient 114 during deceleration. The time t2 is a time when the remaining defocus amount up to the target position is equal to or less than a predetermined value. The time t2 is set in advance through experiments, simulations, and the like. When the remaining defocus amount reaches the in-focus range 104 at time t5, the camera body control unit 318 stops the drive motor 251.

  As described above, when the high-precision mode is set, the camera body control unit 318 stops the movement of the focus lens 212 when the focus lens 212 converges within the in-focus range 103, and instructs the user to take an image. Accept. When the low-precision mode is set, when the focus lens 212 converges within the in-focus range 104, the movement of the focus lens 212 is stopped and a user's imaging instruction is accepted. When the low-precision mode is set, the focus lens 212 converges in the in-focus range more quickly than when the high-precision mode is set. I can receive it.

  When the low-precision mode is set, when the focus lens 212 converges within the in-focus range 104, the user's imaging instruction may be accepted while continuing to move the focus lens 212. In this case, the movement of the focus lens 212 may be continued while notifying the user that it is within the focusing range 104. As a result, the user can decide whether to perform the second-stage depression because it is within the in-focus range 104, or whether to perform the second-stage depression after waiting for a higher accuracy state. . When the focus lens 212 converges within the focus range that is the third error range smaller than the focus range 104, the movement of the focus lens 212 may be stopped. Thereby, when the low-accuracy mode is set, the permissible focusing range can be further reduced. Further, when the focus lens 212 converges within the in-focus range 104, the movement of the focus lens 212 may be continued with a gentler velocity gradient than the target velocity gradient 114. As a result, the focus lens 212 can be prevented from protruding outside the focus range 104.

  A case where either the high accuracy mode or the low accuracy mode is automatically selected will be described. The switching determination time Tjud in the figure is set based on a predetermined condition. For example, it is possible to take statistics of a period that the user feels late with respect to the period from when SW2 is detected until the actual shooting process is performed, and to determine the average time as the switching determination time Tjud. As will be described in detail later, control using the switching determination time Tjud is particularly effective when SW1 and SW2 are detected substantially simultaneously.

  When the camera body control unit 318 detects SW1, the camera body control unit 318 estimates the defocus position in the switching determination time Tjud. More specifically, when SW1 is detected, a defocus amount is calculated, and a determination table corresponding to the calculated defocus amount is selected. Then, using the selected determination table, it is determined whether the defocus position in the high accuracy mode is within the in-focus range 104 at the switching determination time Tjud. Similarly, at the switching determination time Tjud, it is determined whether the defocus position in the low accuracy mode is within the in-focus range 103 using the selected determination table. The camera body control unit 318 drives and controls the focus lens 212 in either the high accuracy mode or the low accuracy mode according to these determination results. As shown in FIG. 2, at the switching determination time Tjud, the defocus position in the low accuracy mode is within the focus range 104, and the defocus position in the high accuracy mode is not within the focus range 103. In this case, the low precision mode is set. Thereby, the drive control along the characteristic curve 102 in FIG. 2A can be realized. Compared with the case of setting to the high accuracy mode, AF can be performed quickly, and the subject can be photographed at an earlier stage than the switching determination time Tjud.

  FIG. 3 is a diagram illustrating a case where either the high accuracy mode or the low accuracy mode is automatically selected. Specifically, it is a diagram showing the movement of the focus lens 212. 3A and 3B, the horizontal axis indicates time, and the vertical axis indicates the defocus amount of the focus lens 212. In FIG. 3A, the solid line indicates the characteristic curve 105 when the high accuracy mode is set, and the broken line indicates the characteristic curve 106 when the low accuracy mode is set. Further, the case where the defocus amount is smaller than the defocus amount D1 is shown. In FIG. 3B, the solid line indicates the characteristic curve 107 when the high accuracy mode is set, and the broken line indicates the characteristic curve 108 when the low accuracy mode is set. Further, the case where the defocus amount is larger than the defocus amount D1 is shown.

  As shown in FIG. 3A, the defocus amount D2 is smaller than the defocus amount D1. Therefore, at the switching determination time Tjud, the defocus position in the low accuracy mode is within the focus range 104, and the defocus position in the high accuracy mode is also within the focus range 103. In this case, the camera body control unit 318 sets the high accuracy mode. As a result, drive control along the characteristic curve 105 in FIG. Accordingly, it is possible to photograph the subject with high focusing accuracy earlier than the switching determination time Tjud.

  As shown in FIG. 3B, the defocus amount D3 is larger than the defocus amount D1. For this reason, at the switching determination time Tjud, the defocus position in the low accuracy mode is not within the focus range 104, and the defocus position in the high accuracy mode is not within the focus range 103. In this case, the camera body control unit 318 sets the low accuracy mode. Thereby, drive control along the characteristic curve 108 of FIG. 3B can be realized. Therefore, although the switching determination time Tjud elapses, AF can be performed quickly and the subject can be photographed as compared with the case where the high accuracy mode is set.

  FIG. 4 is a diagram for explaining a case where the focus lens 212 is focused and followed with respect to a subject moving at a constant speed. FIG. 4A is a diagram illustrating the movement of the focus lens 212. In the figure, the alternate long and short dash line indicates the locus 123 of movement of the subject. The solid line shows the characteristic curve 121 in the high accuracy mode. A broken line shows the characteristic curve 122 of the low accuracy mode. In the low-accuracy mode, the rising response is made faster than in the high-accuracy mode, so that overshoot may occur as shown in the figure.

  First, the camera body control unit 318 performs quantitative drive control, which is the drive control described with reference to FIGS. 2 and 3, in order to focus the focus lens 212 on the subject. Thereby, the focus lens 212 is moved to the in-focus range. Then, follow-up drive control for following the moving subject is performed. The camera body control unit 318 can set either the high accuracy mode or the low accuracy mode according to the user setting.

  When the high accuracy mode is set, as shown in the characteristic curve 121, the quantitative driving is started from time t0 that is the time when SW1 is detected, and the quantitative driving is completed at time t4. At time t4, the operation shifts to follow-up driving. When the low accuracy mode is set, as shown by the characteristic curve 122, the quantitative driving is started from time t0. By driving at higher speed, the quantitative driving is completed at time t2 before time t4. At time t2, the driving is shifted to follow-up driving. When the low-accuracy mode is set, when photographing a moving subject, the quantitative driving is completed quickly, so that the photographing timing can be obtained at an earlier stage. As a result, the possibility of missing the shooting timing can be reduced.

  A case where either the high accuracy mode or the low accuracy mode is automatically selected will be described. The switching determination time Tjud in the figure is as described in FIG. When the camera body control unit 318 detects SW1, the camera body control unit 318 estimates the defocus position in the switching determination time Tjud. More specifically, when SW1 is detected, a defocus amount is calculated, and a determination table corresponding to the calculated defocus amount is selected. Then, using the selected determination table, it is determined whether the defocus position in the low accuracy mode is within the in-focus range 104 at the switching determination time Tjud. Similarly, at the switching determination time Tjud, it is determined whether the defocus position in the high accuracy mode is within the focusing range 103 using the selected determination table. The camera body control unit 318 drives and controls the focus lens 212 in either the high accuracy mode or the low accuracy mode according to these determination results. For example, as shown in FIG. 4A, at the switching determination time Tjud, the defocus position in the low accuracy mode is within the focus range 104, and the defocus position in the high accuracy mode is in the focus range 103. If it is not within, set to the low accuracy mode.

  The camera body control unit 318 may compare the time at which the focusing range 104 in the characteristic curve 121 is reached with the time at which the quantitative driving in the characteristic curve 122 ends. In the example shown in FIG. 4A, time t3 and time t2 are compared. If the time t2 is earlier than the time t3, the control is performed using the control parameter in the low accuracy mode. The time at which the focusing range 104 in the characteristic curve 121 is reached may be compared with the time at which the focusing range 104 in the characteristic curve 122 is reached. In the example shown in FIG. 4A, time t3 is compared with time t1.

  Even if the focus lens 212 is driven in the low-accuracy mode, the probability that the focus lens 212 does not fall within the in-focus range 103 may be about several percent. Therefore, in the above description, the in-focus range allowed in the high-accuracy mode and the low-accuracy mode are different, but the in-focus range may be the same and the probability of being in the in-focus range may be different. That is, it is good also as a structure which selects the mode which has a mutually different focus probability instead of the structure which selects a mutually different tolerance range.

  FIG. 4B illustrates a determination table for switching between the high accuracy mode and the low accuracy mode depending on the focusing accuracy. The determination table associates the driving time with the probability of being in the in-focus range 103 when the high accuracy mode is set. Similarly, when the low-accuracy mode is set, the driving time is associated with the probability of being in the focusing range 103. In the low-accuracy mode, two cases are shown: a case where there is no correction indicating the probability itself falling within the focusing range 103 and a case where there is correction where the probability falling within the focusing range 103 is multiplied by a determination correction coefficient. . Here, the determination correction coefficient is 0.9. Further, the driving time and the switching determination are associated with each other. In the item of switching determination, the numerical value 1 indicates the high accuracy mode, and the numerical value 2 indicates the low accuracy mode. A numerical value 1 is set when the probability of the low accuracy mode (with correction) is higher than the probability of the high accuracy mode, and a numerical value 2 is set when it is lower than the probability of the high accuracy mode. By appropriately adjusting the determination correction coefficient, the numerical value of the item of switching determination can be changed. The determination table is generated in advance through experiments, simulations, and the like. For example, in a driving test of the focus lens 212 in the manufacturing process, if data for each driving time is recorded as a log, the determination table can be generated using the log.

  In the high-accuracy mode, the control parameters are set so that the focus lens 212 is finally within the focusing range 103 with a probability of 100%. In the low-accuracy mode (without correction), the control parameters are set so that the focus lens 212 is finally within the focus range 103 with a probability of 85%. For example, in the high accuracy mode, it can be seen that 90 ms after the start of driving falls within the focusing range 103 with a probability of 100%. It can be seen that the probability of being in the in-focus range 103 is 0% after 50 ms from the start of driving. On the other hand, in the low-accuracy mode (without correction), it can be seen that after 40 ms from the start of driving, it falls within the focusing range 103 with a probability of 85%. It can be seen that after 20 ms from the start of driving, the probability of being in the focusing range 103 is 0%.

  The camera body control unit 318 determines whether or not the focus lens 212 is within the in-focus range 103 during the switching determination time Tjud by referring to the determination table, and determines the high accuracy mode and the low accuracy mode according to the determination result. Set to one of the accuracy modes. A case where the switching determination time Tjud is set 50 ms after the start of driving will be described. The camera body control unit 318 compares the probability in the high accuracy mode and the probability in the low accuracy mode (with correction) 50 ms after the start of driving. As shown in FIG. 4B, when the drive motor 251 is driven in the high accuracy mode, it can be seen that the probability that the focus lens 212 enters the in-focus range 103 is 0%. On the other hand, when the drive motor 251 is driven in the low accuracy mode (with correction), it can be seen that the probability that the focus lens 212 enters the in-focus range 103 is 76.5%. Since the probability in the low accuracy mode (with correction) is higher than the probability in the high accuracy mode, the camera body control unit 318 automatically switches to control the drive motor 251 in the low accuracy mode. Note that the probability in the low accuracy mode (without correction) and the probability in the high accuracy mode may be compared. The user may register an allowable probability using the operation member 315. The low accuracy mode may be selected when the probability is higher than the probability in the high accuracy mode and higher than the registered probability.

  As described above, in the high accuracy mode, even when AF is not in time for the shooting timing, in the low accuracy mode, the shooting timing may be in time. In such a case, the camera body control unit 318 can automatically set the low accuracy mode using the determination table.

  FIG. 5 is a diagram illustrating a display example of the selection screen in the autofocus mode. FIG. 5A is a diagram illustrating a display example of an AF accuracy selection screen. The user can select the AF accuracy from the custom menu settings. When “high accuracy” indicating the high accuracy mode is selected as the AF accuracy, the camera body control unit 318 controls the drive motor 251 using the control parameters for the high accuracy mode described above. When “low accuracy” is selected, the camera body control unit 318 controls the drive motor 251 using the control parameters for the low accuracy mode described above. When “auto selection” is selected, the high accuracy mode and the low accuracy mode are automatically switched.

  FIG. 5B is a diagram illustrating a display example of an AF accuracy option selection screen. If the AF accuracy is set to “low accuracy” and the AF accuracy option is set to “AF-C”, shooting in the low accuracy mode is performed when shooting with “AF-C”. . In this case, the difference in AF speed becomes significant between the high accuracy mode and the low accuracy mode, particularly during quantitative driving. If the AF accuracy is set to “low accuracy” and the AF accuracy option is set to “AF-S”, shooting in the low accuracy mode is performed when shooting with “AF-S”. . When the AF accuracy is set to “low accuracy” and the AF accuracy option is selected to “all AF mode”, the image is shot with either “AF-C” or “AF-S”. Even in this case, shooting in the low accuracy mode is performed.

  FIG. 6 is a flowchart showing an example of processing related to the photographing operation in the auto selection mode. This flow is started when the camera body control unit 318 detects that SW1 is turned on in the state where the auto selection mode is set. The camera main body control unit 318 has already acquired the drive control table and the determination table when the interchangeable lens 200 is attached.

  When the camera body control unit 318 detects that SW1 is turned on, the camera body control unit 318 executes AF in the high accuracy mode (step S101). Specifically, the camera body control unit 318 first acquires the defocus amount detected by the AF sensor 307. Then, the drive amount of the focus lens 212 is calculated from the defocus amount. When the drive amount is calculated, a drive control table corresponding to the drive amount is selected, and AF is executed using the control parameter in the high accuracy mode.

  The camera body control unit 318 determines whether the timer of SW1 is turned off (step S102). If it is determined that the timer of SW1 has been turned off (Yes in step S102), the series of processing ends. If it is determined that the timer of SW1 is not turned off (No in step S102), it is determined whether SW2 is turned on (step S103). If it is determined that SW2 is not turned on (No in step S103), the process proceeds to step S102. If it is determined that SW2 is turned on (Yes in step S103), it is determined whether the release time lag has elapsed (step S104). Here, the release time lag is SW2, that is, the time from when a shooting instruction is issued until when shooting is actually possible. The release time lag is a period during which AF, photometry, and other shooting preparations are completed. If it is determined that the release time lag has not elapsed (No in step S104), the mode is switched to the low accuracy mode (step S105). Specifically, the drive control table selected in step 101 is referred to, and AF is executed using the control parameters in the low accuracy mode. As described above, when shooting a moving subject, SW1 and SW2 may be pressed almost simultaneously. In this case, it is considered that SW2 is pressed before the release time lag elapses. Therefore, when the release time lag is long due to AF, the release time lag can be shortened by switching to the low accuracy mode.

  If the release time lag elapses after switching to the low-accuracy mode, or if it is determined in step 104 that the release time lag has already elapsed (Yes in step S104), the shooting process is executed (step S106). The process ends.

  In the above description, the camera body control unit 318 uses the determination table to determine whether to set the high accuracy mode or the low accuracy mode, but can also determine without using the determination table. When the drive amount of the focus lens 212 is determined, the time for the drive amount may be estimated using a relational expression between the drive amount and time.

  In the above description, as shown in FIG. 2B, the target speed gradient during acceleration / deceleration is represented by a straight line, but may be represented by a curve. Alternatively, the target speed gradient may be calculated using a table in which parameters related to the target speed gradient are described.

  In the above description, the target speed and the target speed gradient are used as the control parameters, but other control parameters may be used as long as they affect the characteristic curve of the drive motor 251. For example, the target acceleration of the drive motor 251 can be used. In this case, the camera body control unit 318 changes the speed control of the focus lens 212 by controlling the acceleration of the focus lens 212.

  In the above description, the digital camera 100 is an interchangeable lens type, but may be a lens integrated type. In the above description, the case where phase difference AF is adopted as the AF method is taken as an example, but contrast AF may be adopted.

  In the above description, the configuration has two modes, the high accuracy mode and the low accuracy mode, but may have a configuration having three or more modes. For example, a standard mode may be provided in addition to the high accuracy mode and the low accuracy mode. In the standard mode, for example, the target speed gradient during acceleration is set between the target speed gradient during acceleration in the low accuracy mode and the target speed gradient during acceleration in the high accuracy mode. Similarly, the target speed gradient during deceleration is set between the target speed gradient during deceleration in the low accuracy mode and the target speed gradient during deceleration in the high accuracy mode. In the standard mode, an error range between the error range allowed in the high accuracy mode and the error range allowed in the low accuracy mode may be allowed for the target position of the focus lens. Thereby, more selectable accuracies can be provided to the user. The error range allowed in the standard mode may be set to be the same as the error range allowed in the high accuracy mode.

  Further, the smaller the driving amount of the focus lens 212, the higher the probability of overshooting. Therefore, the control parameter may be set so that the characteristic curve becomes gentler in the range with the smaller drive amount in the divided range.

  In the above description, the fixed drive and the combination of the fixed drive and the follow-up drive have been described as examples. However, as long as the drive motor 251 can be controlled, other drive methods and other combinations may be used. The camera body control unit 318 may perform PID control on the drive motor 251 of the focus lens drive unit 250. In this case, the proportional gain may be different between the high accuracy mode and the low accuracy mode. Thereby, the speed can be changed between the high accuracy mode and the low accuracy mode. In addition to the proportional gain, at least one of the integral gain and the differential gain may be dynamically changed.

  In the above description, the determination table is set for each divided range of the focus lens 212, but may be set for each temperature range further divided for temperature. In PID control, the temperature in the operating environment can be a disturbance. Therefore, the accuracy of PID control can be improved by detecting the environmental temperature and using a determination table corresponding to the environmental temperature. Further, the user may select the focusing accuracy by selecting the speed. Specifically, a high speed mode may be provided instead of the low accuracy mode, and a low speed mode may be provided instead of the high accuracy mode.

  In the above description, when the auto selection mode is set, either the high accuracy mode or the low accuracy mode is set using the switching determination time. However, depending on the shooting mode, the high accuracy mode and the low accuracy mode are set. You may set to either. For example, if the landscape mode is set, the high accuracy mode may be set. When the landscape mode is set, it can be considered that a stationary subject is often photographed. Therefore, in this case, the focusing accuracy is given priority over the time until focusing. On the other hand, for example, if the sport mode is set, the low precision mode may be set. When the sports mode is set, it is considered that the moving subject is often photographed. Therefore, in this case, priority is given to the speed until focusing is achieved over focusing accuracy.

In the above description, the average of the statistics that the user feels late is determined as the switching determination time Tjud, but may be determined using the release time lag Trls. Specifically, it can be calculated by the following formula.
Tjud = α × Trls + β
Here, α is an adjustment correction coefficient, and β is an adjustment offset.
By appropriately adjusting the adjustment correction coefficient and the adjustment offset, the switching determination time Tjud can be adjusted. The switching determination time Tjud may be changed according to the subject speed, may be changed according to the continuous shooting speed, or may be changed according to the environmental temperature. The switching determination time Tjud may be set for each section range of the focus lens 212. Further, the switching determination time Tjud may be determined using a release time lag excluding AF. If the release time lag excluding AF is longer than the time required to complete AF, the AF speed need not be increased in the first place. Therefore, for example, if the release time lag excluding AF is used as the switching determination time Tjud, the mode can be changed according to the release time lag excluding AF. For example, if the release time lag excluding AF is somewhat short, the low accuracy mode may be set. If the drive amount of the focus lens 212 is large to some extent, AF is likely to take a longer time than the release time lag excluding AF. In this case, there is a high possibility that the low-precision mode or the high-precision mode is not within the in-focus range. Therefore, a value obtained by adding an adjustment offset to the release time lag excluding AF may be used as the switching determination time Tjud. Further, the switching determination time may be set according to the defocus amount. The larger the defocus amount, the longer the time required to complete AF. Therefore, it is preferable to set the switching determination time longer as the defocus amount increases while considering a period during which the user feels late.

  The focus mode may include a power focus mode. In this case, the camera body 300 includes, for example, a rotary dial as the operation member 315. In the power focus mode, the camera body 300 detects a rotation operation of the rotary dial by the user. Then, the focus lens 212 is moved by driving the drive motor 251 in accordance with the rotation amount of the rotary dial. The power focus mode may include the above-described high accuracy mode, low accuracy mode, and auto selection mode. For example, if the low accuracy mode is set, the target position determined according to the rotation amount is driven at a higher speed than when the high accuracy mode is set.

  The placing pin mode may be included as the focus mode. In the placement pin mode, when the subject is photographed, the focus is locked to a specific subject distance in advance. The standing pin mode may include the above-described high accuracy mode, low accuracy mode, and auto selection mode. For example, if the low accuracy mode is set, the target position that is a specific subject distance is driven at a higher speed than when the high accuracy mode is set.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the shooting operation flow in the claims, the description, and the drawings, even if it is described using “first,” “next,” etc. for convenience, it means that it is essential to carry out in this order. Not what you want.

  100 digital camera, 101 characteristic curve, 102 characteristic curve, 103 focusing range, 104 focusing range, 105 characteristic curve, 106 characteristic curve, 107 characteristic curve, 108 characteristic curve, 111 target speed gradient, 112 target speed gradient, 113 target Velocity gradient, 114 Target velocity gradient, 121 characteristic curve, 122 characteristic curve, 123 locus, 200 interchangeable lens, 201 optical axis, 210 photographing lens, 211 zoom lens, 212 focus lens, 220 interchangeable lens control unit, 230 system memory, 240 Zoom lens drive unit, 250 focus lens drive unit, 251 drive motor, 252 encoder, 260 lens mount, 300 camera body, 301 main mirror, 302 sub mirror, 303 focus plate, 304 penta prism, 3 5 eyepiece optical system, 306 finder window, 307 AF sensor, 308 image sensor, 309 A / D converter, 310 internal memory, 311 image processing unit, 312 recording medium IF, 313 display control unit, 314 display unit, 315 operation member 316 release switch, 317 system memory, 318 camera body control unit, 360 camera mount, 400 recording medium

Claims (14)

A setting unit for setting a control parameter related to the accuracy of the focus;
An imaging apparatus comprising: a control unit that controls a moving speed of the focus lens based on the setting by the setting unit.   The setting unit includes a first mode in which a control parameter for the moving speed of the focus lens is a first parameter, an allowable range of deviation with respect to a target position of the focus lens is a first range, and the control parameter is the first parameter. The imaging apparatus according to claim 1, wherein the second parameter is different from the first parameter, and the allowable range is set to any one of a second mode different from the first range. The first mode is a high-accuracy mode that allows a first error range with respect to the target position of the focus lens, and the second mode is a low-accuracy that allows a second error range that is larger than the first error. Mode
When the first mode is selected, the control unit allows up to a first speed when the first mode is selected, and allows a second speed greater than the first speed when the second mode is selected. The imaging device according to claim 2.   When the first mode is selected, when the focus lens converges within the first error range with respect to the target position, the control unit stops moving the focus lens and instructs the user to take an image. And when the second mode is selected, when the focus lens converges within the second error range with respect to the target position, the user is instructed to take an image while continuing to move the focus lens. The imaging device according to claim 3 to receive.   When the second mode is selected, the control unit stops the movement of the focus lens when the focus lens converges within a third error range smaller than the second error range with respect to the target position. The imaging device according to claim 4.   When the second mode is selected, the control unit is configured such that when the focus lens converges within the second error range with respect to the target position, the focus lens is moved at a third speed smaller than the second speed. The imaging apparatus according to claim 4, wherein the movement of the camera continues.   The setting unit includes a first mode in which a control parameter for the moving speed of the focus lens is a first parameter, a focus probability with respect to a target position of the focus lens is a first probability, and the control parameter is the first parameter. The imaging apparatus according to claim 1, wherein the second parameter is different and the focus probability is set to any one of a second mode different from the first probability.   The imaging device according to claim 2, wherein the setting unit sets the first mode or the second mode in accordance with an input instruction from a user.   The imaging device according to any one of claims 2 to 6, wherein the setting unit automatically sets one of the first mode and the second mode based on a switching determination time.   The imaging apparatus according to claim 9, wherein the switching determination time is set according to a defocus amount.   The imaging apparatus according to claim 9, wherein the switching determination time is set according to a subject speed.   The imaging apparatus according to claim 9, wherein the switching determination time is set according to a continuous shooting speed.   The imaging device according to claim 1, wherein the control unit changes speed control of the focus lens by controlling acceleration of the focus lens as the control parameter. A setting step for setting a control parameter relating to focus accuracy;
A control program for causing a computer to execute a control step of controlling a moving speed of the focus lens based on the setting.

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