JP2013057867A - Interchangeable lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interchangeable lens capable of accurately driving a focus lens, even while a variable power lens is being driven.SOLUTION: An interchangeable lens includes a varifocal optical system, storage means storing position information on a position of the focus lens corresponding to each of a plurality of photographic distances on each of a plurality of positions of a variable power lens, receiving means receiving a command for driving the focus lens up to a predetermined absolute position from a camera body, first calculation means calculating a drive target position of the focus lens corresponding to the predetermined absolute position, drive means driving the focus lens up to the drive target position, determination means determining whether or not the variable power lens is in the middle of driving, when the command is received by the receiving means, and second calculation means calculating a predicted target position where a change of the drive target position by the drive of the variable power lens is predicted, when the variable power lens is in the middle of driving. When the variable power lens is in the middle of driving, the drive means drives the focus lens up to the predicted target position.

Description

  The present invention relates to an interchangeable lens.

  An imaging optical system including a variable power lens for adjusting the focal length and a focus lens for adjusting the photographing distance (focus position) is known. In such an imaging optical system, when the zoom lens is moved, the relationship between the shooting distance and the position of the focus lens changes. That is, when the zoom lens is moved, the shooting distance (in other words, the focal position) is changed. There are so-called varifocal optical systems that change. For example, Patent Document 1 describes a lens control device in which the position of a focus lens for focusing on an imaging surface differs depending on the subject distance even when the focal lengths are equal.

Japanese Patent Laid-Open No. 3-96908

  The lens control device described in Patent Document 1 has a problem that the focus lens cannot be driven correctly when a drive command to the absolute position of the focus lens is received during driving of the variable power lens.

  The invention according to claim 1 includes a zoom lens and a focus lens, which are arranged on the same optical axis that can be driven in the optical axis direction, and the relationship between the shooting distance and the position of the focus lens is the position of the zoom lens. A varifocal optical system that changes according to the position of the zoom lens, a storage unit that stores position information regarding the position of the focus lens corresponding to each of a plurality of shooting distances, and a camera body that can be attached and detached. Mount means to be attached, receiving means for receiving from the camera body a command to drive the focus lens to a predetermined absolute position expressed with reference to a position corresponding to a predetermined shooting distance, and current position and position information of the zoom lens And a first calculation means for calculating a drive target position of the focus lens corresponding to a predetermined absolute position, and a first calculation means Driving means for driving the focus lens to the calculated drive target position, determination means for determining whether or not the variable magnification lens is being driven when a command is received by the reception means, and the variable magnification lens is determined by the determination means And a second calculating unit that calculates a predicted target position that predicts a change in the drive target position due to driving of the variable power lens when it is determined that the variable power lens is being driven. When it is determined that the lens is being driven, the focus lens is driven to the predicted target position.

  According to the present invention, it is possible to correctly drive the focus lens even while the zoom lens is being driven.

It is the perspective view which showed the lens-interchangeable camera system to which this invention is applied. It is sectional drawing which showed the lens-interchangeable camera system to which this invention is applied. It is a schematic diagram which shows the detail of the holding | maintenance part 102,202. It is a timing chart which shows the example of command data communication. It is a timing chart which shows the example of hotline communication. It is a figure which shows the positional relationship of the variable power lens 210b and the focus lens 210c. It is the figure which expanded a part of FIG. It is a flowchart of the process at the time of the absolute position drive command reception during the drive of the zoom lens 210b. It is the figure which expanded a part of FIG. It is a figure which shows drive target position Pc when predetermined time Ts passes after receiving an absolute position drive command. It is a figure which shows drive target position Pc when predetermined time Ts passes after receiving an absolute position drive command.

(First embodiment)
FIG. 1A is a perspective view showing an interchangeable lens type camera system to which the present invention is applied. FIG. 1 (a) shows only the devices and apparatuses according to the present invention, and illustration and description of the other devices and apparatuses are omitted. The camera system 1 includes a camera body 100 and an interchangeable lens 200 that can be attached to and detached from the camera body 100.

  The camera body 100 is provided with a body side mount 101 to which the interchangeable lens 200 is detachably attached. At a position near the body-side mount portion 101 (inner peripheral side of the body-side mount portion 101), a holding portion (electrically holding the contact point in a state of partially protruding toward the inner peripheral side of the body-side mount portion 101) ) 102 is provided. The holding portion 102 is provided with a plurality of contacts.

  In addition, the interchangeable lens 200 is provided with a lens side mount portion 201 corresponding to the body side mount portion 101 to which the camera body 100 is detachably attached. In the vicinity of the lens side mount part 201 (inner peripheral side of the lens side mount part 201), a holding part (electrical) that holds the contact in a state of partially protruding to the inner peripheral side of the lens side mount part 201 ) 202 is provided. The holding portion 202 is provided with a plurality of contacts.

  When the interchangeable lens 200 is attached to the camera body 100, the holding part 102 on the camera body 100 side provided with a plurality of contacts is electrically connected to the holding part 202 on the interchangeable lens 200 side provided with a plurality of contacts. Physically connected. Both holders 102 and 202 are used for power supply from the camera body 100 to the interchangeable lens 200 and transmission / reception of signals between the camera body 100 and the interchangeable lens 200.

  An imaging element 104 such as a CMOS or a CCD is provided behind the body side mount 101 in the camera body 100. Above the camera body 100, a button 105 serving as an input device is provided. The user uses the input device such as the button 105 to instruct the camera body 100 to take a picture, set shooting conditions, and the like. On the side surface (a surface different from the mount surface) of the interchangeable lens 200, a slide switch 219 that is a zoom operation member for driving a variable power lens (described later) provided in the interchangeable lens 200 is provided.

  FIG. 1B is a front view of the slide switch 219. The slide switch 219 is configured to be movable within the movable ranges 220 and 221. The movable range 220 located above FIG. 1B corresponds to the telephoto direction, and the movable range 221 located below FIG. 1B corresponds to the wide-angle direction. The slide switch 219 is configured to be positioned at the center of both the movable ranges 220 and 221 when a force is not applied from the outside by a spring or the like (not shown). When the photographer pushes up the slide switch 219 in the direction of the movable range 220, a zoom lens described later is driven at a speed corresponding to the amount of movement of the slide switch 219, and the focal length of the interchangeable lens 200 changes to the telephoto side. Similarly, when the slide switch 219 is moved in the direction of the movable range 221, the focal length of the interchangeable lens changes to the wide angle side.

  FIG. 2 is a cross-sectional view showing an interchangeable lens type camera system to which the present invention is applied. The interchangeable lens 200 includes an imaging optical system 210 that forms a subject image. The imaging optical system 210 includes a plurality of lenses 210 a to 210 d and a diaphragm 211 arranged on the same optical axis O. The plurality of lenses 210a to 210d includes a zoom lens 210b that changes the focal length of the imaging optical system 210 and a focus lens 210c that adjusts the focus position of the subject image.

  The imaging optical system 210 is a so-called varifocal optical system. That is, when the zoom lens 210b is driven and the focal length of the imaging optical system 210 changes, the relationship between the shooting distance and the position of the focus lens 210c on the optical axis changes. For example, the zoom lens 210b is located at a position where the focal length of the imaging optical system 210 is 20 mm, and the focus is set at a position where the shooting distance is 3 m (the subject is in focus 3 m away from the imaging surface of the image sensor 104). When the zoom lens 210b is driven when the lens 210c is present and the focal length is 40 mm, the shooting distance of the focus lens 210c is not 3 m (for example, 4 m or 6 m). The relationship between the zoom lens 210b and the focus lens 210c will be described in detail later.

  Inside the interchangeable lens 200, a lens control unit 203 that controls each part of the interchangeable lens 200 is provided. The lens control unit 203 includes a microcomputer (not shown) and its peripheral circuits. The lens control unit 203 is connected to a lens side first communication unit 217, a lens side second communication unit 218, a zoom drive unit 212, an aperture drive unit 213, a focus drive unit 214, a ROM 215, and a RAM 216.

  The lens-side first communication unit 217 and the lens-side second communication unit 218 transmit and receive signals to and from the camera body 100 via the communication contacts of the holding units 102 and 202. The lens side first communication unit 217 and the lens side second communication unit 218 are communication interfaces on the interchangeable lens 200 side, respectively. The lens control unit 203 performs communication (hotline communication, command data communication) described later with the camera body 100 (body control unit 103 described later) using these communication interfaces.

  The zoom driving unit 212 includes a motor (for example, an actuator such as a stepping motor) that generates a driving force and a transmission system (for example, a combination of a plurality of gears) that transmits the driving force to the variable power lens 210b. . The zoom drive unit 212 is controlled by the lens control unit 203, and drives the zoom lens 210b in the direction of the optical axis O at a drive speed specified by the lens control unit 203. That is, the interchangeable lens 200 is a zoom lens having a so-called power zoom function.

  The focus drive unit 214 has the same configuration as the zoom drive unit 212 except that the drive target is the focus lens 210c. Similarly to each of these driving units, the diaphragm driving unit 213 changes the aperture diameter of the diaphragm 211 by driving the diaphragm 211 by a predetermined motor.

  The lens control unit 203 is configured to be able to acquire the positions on the optical axis O of the variable magnification lens 210b and the focus lens 210c. For example, an encoder (not shown) may be provided to detect the position of the zoom lens 210b or the focus lens 210c, or an input signal to an actuator (stepping motor or the like) that drives the zoom lens 210b or the focus lens 210c. The position may be detected by monitoring the above.

  The ROM 215 is a nonvolatile storage medium, and stores in advance a predetermined control program executed by the lens control unit 203, a maximum driving speed of a diaphragm 211 described later, and the like. The RAM 216 is a volatile storage medium and is used as a temporary storage area for various data by the lens control unit 203.

  A shutter 115 for controlling the exposure state of the image sensor 104 and an optical filter 116 combining an optical low-pass filter and an infrared cut filter are provided on the front surface of the image sensor 104. The subject light that has passed through the imaging optical system 210 enters the image sensor 104 via the shutter 115 and the filter 116.

  Inside the camera body 100, a body control unit 103 that controls each part of the camera body 100 is provided. The body control unit 103 includes a microcomputer (not shown), a RAM, and peripheral circuits thereof.

  A body-side first communication unit 117 and a body-side second communication unit 118 are connected to the body control unit 103. The body-side first communication unit 117 is connected to the holding unit 102, and can transmit and receive signals to and from the lens-side first communication unit 217 through a plurality of contacts provided on the holding unit 102. Similarly, the body side second communication unit 118 can transmit and receive signals to and from the lens side second communication unit 218. In other words, each of the body-side first communication unit 117 and the body-side second communication unit 118 is a body-side communication interface. The body control unit 103 performs communication (hotline communication and command data communication) described later with the interchangeable lens 200 (lens control unit 203) using these communication interfaces.

  A display device 111 configured by an LCD panel or the like is disposed on the back surface of the camera body 100. The body control unit 103 displays various menu screens for setting an image of a subject (a so-called through image) based on the output of the image sensor 104, shooting conditions, and the like on the display device 111.

(Description of holding units 102 and 202)
FIG. 3 is a schematic diagram showing details of the holding units 102 and 202. In FIG. 3, the holding portion 102 is arranged on the right side of the body-side mount portion 101 in accordance with an actual mount structure. That is, the holding portion 102 according to the present embodiment is disposed at a location deeper than the mount surface of the body-side mount portion 101 (a location on the right side of the body-side mount portion 101 in FIG. 3). Similarly, the holding unit 202 is arranged on the right side of the lens side mount unit 201 because the holding unit 202 of the present embodiment is arranged at a position protruding from the mount surface of the lens side mount unit 201. Represents. Since the holding unit 102 and the holding unit 202 are arranged in this way, the camera body 100 and the interchangeable lens 200 are mounted by bringing the mounting surface of the body side mounting unit 101 into contact with the mounting surface of the lens side mounting unit 201. When combined, the holding unit 102 and the holding unit 202 are connected, and the electrical contacts provided in both holding units are also connected. Since such a mount structure is well known, further explanation and illustration are omitted.

  As shown in FIG. 3, the holding unit 102 has 12 contacts BP <b> 1 to BP <b> 12. The holding unit 202 has twelve contacts LP1 to LP12 corresponding to the twelve contacts described above.

  The contacts BP1 and BP2 are connected to the first power supply circuit 130 in the camera body 100. The first power supply circuit 130 has a drive system such as an actuator at the contact point BP1 and has a relatively large power consumption (excluding the zoom drive unit 212, the aperture drive unit 213, the focus drive unit 214, etc.) in the interchangeable lens 200. Supply the operating voltage of each part. That is, the operating voltage of each part in the interchangeable lens 200 excluding the above driving parts is supplied from the contact BP1 and the contact LP1. The voltage value that can be supplied to the contact point BP1 has a range between the minimum voltage value and the maximum voltage value (for example, a voltage width in the 3V range). The voltage value that is normally supplied is the maximum voltage value and the minimum voltage value. Is a voltage value in the vicinity of the intermediate value. As a result, the current value supplied from the camera body 100 side to the interchangeable lens 200 side is a current value within a range of about several tens of mA to several hundreds of mA in the power-on state.

  The contact BP2 is a ground terminal corresponding to the operating voltage given to the contact BP1. That is, the contact BP2 and the contact LP2 are ground terminal voltages corresponding to the above operating voltage.

  In the following description, the signal line constituted by the contact point BP1 and the contact point LP1 is referred to as a signal line V33. A signal line constituted by the contact point BP2 and the contact point LP2 is referred to as a signal line GND. These contacts LP1, LP2, BP1, BP2 constitute a power supply system contact for supplying power from the camera body 100 side to the interchangeable lens 200 side.

  The contacts BP3, BP4, BP5, and BP6 are connected to the body-side first communication unit 117. The contact points LP3, LP4, LP5, and LP6 on the interchangeable lens 200 side corresponding to these contact points are connected to the lens-side first communication unit 217. The body-side first communication unit 117 and the lens-side first communication unit 217 transmit and receive signals to and from each other using these contacts (communication system contacts). The contents of communication performed by the body-side first communication unit 117 and the lens-side first communication unit 217 will be described in detail later.

  In the following description, a signal line constituted by the contact BP3 and the contact LP3 is referred to as a signal line CLK. Similarly, the signal line constituted by the contact BP4 and the contact LP4 is signal line BDAT, the signal line constituted by the contact BP5 and the contact LP5 is signal line LDAT, and the signal line constituted by the contact BP6 and the contact LP6 is signaled. Called line RDY.

  The contacts BP7, BP8, BP9, and BP10 are connected to the body-side second communication unit 118. The contacts LP7, LP8, LP9, and LP10 on the interchangeable lens 200 side corresponding to these contacts are connected to the lens-side second communication unit 218. The lens-side second communication unit 218 transmits signals to the body-side second communication unit 118 using these contacts (communication system contacts). The contents of communication performed by the body-side second communication unit 118 and the lens-side second communication unit 218 will be described in detail later.

  In the following description, a signal line constituted by the contact BP7 and the contact LP7 is referred to as a signal line HREQ. Similarly, a signal line composed of the contact point BP8 and the contact point LP8 is signal line HANS, a signal line composed of the contact point BP9 and the contact point LP9 is signal line HCLK, and a signal line composed of the contact point BP10 and the contact point LP10 is signaled. Called line HDAT.

  The contact BP11 and the contact BP12 are connected to the second power supply circuit 131 in the camera body 100. The second power supply circuit 131 supplies a driving voltage of a circuit (zoom driving unit 212, aperture driving unit 213, focus driving unit 214, etc.) having a driving system such as an actuator and a relatively large power consumption to the contact point BP12. That is, the drive voltages of the zoom drive unit 212, the aperture drive unit 213, and the focus drive unit 214 are supplied from the contact point BP12 and the contact point LP12. The voltage value that can be supplied to the contact point BP12 has a range from the minimum voltage value to the maximum voltage value, all of which are larger than the voltage value range that can be supplied to the contact point BP1 (for example, The maximum voltage value that can be supplied to the contact point BP12 is several times the maximum voltage value that can be supplied to the contact point BP1). That is, the voltage value supplied to the contact point BP12 is a voltage value whose magnitude is different from the voltage value supplied to the contact point BP1. The voltage value that is normally supplied to the contact BP12 is a voltage value in the vicinity of an intermediate value between the maximum voltage value and the minimum voltage value that can be supplied to the contact BP12. As a result, the current supplied from the camera body 100 side to the interchangeable lens 200 side has a current value of about 10 mA to several A in the power-on state.

  The contact BP11 is a ground terminal corresponding to the drive voltage given to the contact BP12. That is, the contact BP11 and the contact LP11 are ground terminals corresponding to the drive voltage.

  In the following description, a signal line constituted by the contact BP11 and the contact LP11 is referred to as a signal line PGND. A signal line constituted by the contact BP12 and the contact LP12 is referred to as a signal line BAT. These contacts LP11, LP12, BP11, BP12 constitute a power supply system contact for supplying power from the camera body 100 side to the interchangeable lens 200 side.

  As is apparent from the magnitude relationship between the voltage value (current value) supplied to the contacts BP12 and LP12 and the voltage value (current value) supplied to the contacts BP1 and LP1, the voltages are supplied to the contacts. The difference between the maximum value and the minimum value of the current flowing through the contact point BP11 and the contact point LP11 serving as the ground terminals for each of the voltages is larger than the difference between the maximum value and the minimum value of the current flowing through the contact point BP2 and the contact point LP2. ing. This is because the power consumed by each drive unit having a drive system such as an actuator is larger than that of an electronic circuit such as the lens control unit 203 in the interchangeable lens 200, and the driven parts driven by these drive units. When it is not necessary to drive a member, it depends on each drive part not consuming electric power.

(Description of command data communication)
The lens control unit 203 controls the lens-side first communication unit 217 and receives control data from the body-side first communication unit 117 via the contacts LP3 to LP6, that is, the signal lines CLK, BDAT, LDAT, and RDY. Reception and transmission of response data to the body-side first communication unit 117 are performed in parallel at a first predetermined cycle (for example, 16 milliseconds in this embodiment). Hereinafter, details of communication performed between the lens-side first communication unit 217 and the body-side first communication unit 117 will be described.

  In the present embodiment, communication performed between the lens control unit 203 and the lens-side first communication unit 217 and the body control unit 103 and the body-side first communication unit 117 is referred to as “command data communication”. A transmission line composed of four signal lines (signal lines CLK, BDAT, LDAT, and RDY) used for command data communication is referred to as a first transmission line.

  FIG. 4 is a timing chart showing an example of command data communication. The body control unit 103 and the body-side first communication unit 117 first check the signal level of the signal line RDY at the start of command data communication (T1). The signal level of the signal line RDY indicates whether the lens-side first communication unit 217 can communicate. The lens control unit 203 and the lens-side first communication unit 217 output a signal of H (High) level from the contact LP6 when communication is not possible. That is, the signal level of the signal line RDY is set to H level. When the signal line RDY is at the H level, the body control unit 103 and the body-side first communication unit 117 do not start communication until the signal line RDY is at the L level. Also, the next processing during communication is not executed.

  If the signal line RDY is at L (Low) level, the body control unit 103 and the first body side communication unit 117 output the clock signal 401 from the contact point BP3. That is, the clock signal 401 is transmitted to the first lens side communication unit 217 via the signal line CLK. In synchronization with the clock signal 401, the body control unit 103 and the body side first communication unit 117 output a body side command packet signal 402, which is the first half of the control data, from the contact point BP4. That is, the body side command packet signal 402 is transmitted to the first lens side communication unit 217 via the signal line BDAT.

  When the clock signal 401 is output to the signal line CLK, the lens control unit 203 and the lens-side first communication unit 217 synchronize with the clock signal 401, and the lens-side command packet that is the first half of the response data from the contact LP5. The signal 403 is output. That is, the lens-side command packet signal 403 is transmitted to the first body-side communication unit 117 via the signal line LDAT.

The lens control unit 203 and the lens side first communication unit 217 set the signal level of the signal line RDY to the H level in response to the completion of transmission of the lens side command packet signal 403 (T2). The lens control unit 203 starts a first control process 404 (described later) that is a process according to the content of the received body-side command packet signal 402.

  When the first control process 404 is completed, the lens control unit 203 notifies the lens side first communication unit 217 of the completion of the first control process 404. In response to this notification, the lens side first communication unit 217 outputs an L level signal from the contact LP6. That is, the signal level of the signal line RDY is set to L level (T3). The body control unit 103 and the first body side communication unit 117 output the clock signal 405 from the contact point BP3 in accordance with the change in the signal level. That is, the clock signal 405 is transmitted to the lens side first communication unit 217 via the signal line CLK.

  The body control unit 103 and the first body-side communication unit 117 output a body-side data packet signal 406 that is the latter half of the control data from the contact point BP4 in synchronization with the clock signal 405. That is, the body side data packet signal 406 is transmitted to the lens side first communication unit 217 via the signal line BDAT.

  Further, when the clock signal 405 is output to the signal line CLK, the lens control unit 203 and the lens side first communication unit 217 synchronize with the clock signal 405, and the lens which is the latter half of the response data from the contact LP5 receives the data packet signal. 407 is output. That is, the lens-side data packet signal 407 is transmitted to the first body-side communication unit 117 via the signal line LDAT.

  In response to the completion of transmission of the lens-side data packet signal 407, the lens control unit 203 and the lens-side first communication unit 217 set the signal level of the signal line RDY to the H level again (T4). The lens control unit 203 starts a second control process 408 (described later) that is a process according to the content of the received body-side data packet signal 406.

  Here, the first control process 404 and the second control process 408 performed by the lens control unit 203 will be described.

  For example, a case where the received body-side command packet signal 402 has a content requesting specific data on the interchangeable lens side will be described. As the first control process 404, the lens control unit 203 analyzes the content of the command packet signal 402 and executes a process of generating the requested specific data. Further, as the first control process 404, the lens control unit 203 uses the checksum data included in the command packet signal 402 to easily determine whether there is an error in the communication of the command packet signal 402 from the number of data bytes. The communication error check process to check is also executed. The specific data signal generated in the first control process 404 is output to the body side as a lens-side data packet signal 407. In this case, the body side data packet signal 406 output from the body side after the command packet signal 402 is a dummy data signal (including checksum data) that has no particular meaning for the lens side. In this case, the lens control unit 203 executes the communication error check process as described above using the checksum data included in the body side data packet signal 406 as the second control process 408.

  For example, a case where the received body-side command packet signal 402 is an instruction to drive a lens-side driven member will be described. For example, a case where the command packet signal 402 is an instruction to drive the focus lens 210c and the received body side data packet signal 406 is the drive amount of the focus lens 210c will be described. As the first control process 404, the lens control unit 203 analyzes the content of the command packet signal 402 and generates an acknowledgment signal indicating that the content has been understood. Furthermore, the lens control unit 203 also executes the communication error check process as described above using the checksum data included in the command packet signal 402 as the first control process 404. The acknowledge signal generated in the first control process 404 is output to the body side as a lens side data packet signal 407. In addition, as the second control process 408, the lens control unit 203 executes an analysis process of the contents of the body side data packet signal 406 and uses the checksum data included in the body side data packet signal 406 as described above. Execute the check process.

  When the second control process 408 is completed, the lens control unit 203 notifies the lens side first communication unit 217 of the completion of the second control process 408. Accordingly, the lens control unit 203 causes the lens side first communication unit 217 to output an L level signal from the contact LP6. That is, the signal level of the signal line RDY is set to L level (T5).

  If the received body-side command packet signal 402 is an instruction to drive the lens-side driven member (for example, the focus lens 210c) as described above, the lens control unit 203 notifies the lens-side first communication unit 217. While the signal level of the signal line RDY is set to the L level, the focus driving unit 214 is caused to execute processing for driving the focus lens 210c by the driving amount.

  The communication performed at the above-described time T1 to time T5 is one command data communication. As described above, in one command data communication, body control unit 103 and body side first communication unit 117 transmit body side command packet signal 402 and body side data packet signal 406 one by one. In other words, the body side command packet signal 402 and the body side data packet signal 406 together constitute one control data although it is divided and transmitted for convenience of processing.

  Similarly, in one command data communication, the lens control unit 203 and the lens side first communication unit 217 transmit the lens side command packet signal 403 and the lens side data packet signal 407 one by one. That is, the lens side command packet signal 403 and the lens side data packet signal 407 are combined to form one response data.

  As described above, the lens control unit 203 and the lens-side first communication unit 217 perform reception of control data from the body-side first communication unit 117 and transmission of response data to the body-side first communication unit 117 in parallel. And do it. The contact LP6 and the contact BP6 used for command data communication are contacts through which asynchronous signals (signal level of the signal line RDY / H (High) level or L (Low) level) that are not synchronized with other clock signals are transmitted. is there.

(Description of hotline communication)
The lens control unit 203 controls the lens side second communication unit 218 to transmit lens position data to the body side second communication unit 118 via the contacts LP7 to LP10, that is, the signal lines HREQ, HANS, HCLK, and HDAT. Send. Hereinafter, details of communication performed between the lens-side second communication unit 218 and the body-side second communication unit 118 will be described.

  In the present embodiment, communication performed between the lens control unit 203 and the lens-side second communication unit 218, and the body control unit 103 and the body-side second communication unit 118 is referred to as “hotline communication”. A transmission line composed of four signal lines (signal lines HREQ, HANS, HCLK, and HDAT) used for hot line communication is referred to as a second transmission line.

FIG. 5 is a timing chart showing an example of hotline communication. The body control unit 103 of the present embodiment is configured to start hot line communication every second predetermined period (for example, 1 millisecond in the present embodiment). This period is shorter than the period for performing command data communication. FIG. 5A is a diagram illustrating a state in which hot line communication is repeatedly performed at predetermined intervals Tn. Among the hotline communications that are repeatedly executed, a certain communication period T
FIG. 5B shows a state where x is enlarged. Hereinafter, the procedure of hotline communication will be described based on the timing chart of FIG.

  At the start of hot line communication (T6), body control unit 103 and body-side second communication unit 118 first output an L level signal from contact point BP7. That is, the signal level of the signal line HREQ is set to L level. The lens side second communication unit 218 notifies the lens control unit 203 that this signal has been input to the contact LP7. In response to this notification, the lens control unit 203 starts executing a generation process 501 that generates lens position data. The generation process 501 is a process in which the lens control unit 203 causes the focusing lens position detection unit (not shown) to detect the position of the focus lens 210c and generates lens position data representing the detection result.

  When the lens control unit 203 completes the generation process 501, the lens control unit 203 and the lens-side second communication unit 218 output an L level signal from the contact LP8 (T7). That is, the signal level of the signal line HANS is set to the L level. The body control unit 103 and the body-side second communication unit 118 output the clock signal 502 from the contact BP9 in response to the input of this signal to the contact BP8. That is, a clock signal is transmitted to the lens side second communication unit 218 via the signal line HCLK.

  The lens control unit 203 and the second lens-side communication unit 218 output a lens position data signal 503 representing lens position data from the contact LP10 in synchronization with the clock signal 502. That is, the lens position data signal 503 is transmitted to the body-side second communication unit 118 via the signal line HDAT.

  When the transmission of the lens position data signal 503 is completed, the lens control unit 203 and the second lens side communication unit 218 output an H level signal from the contact LP8. That is, the signal level of the signal line HANS is set to the H level (T8). The body-side second communication unit 118 outputs an H-level signal from the contact LP7 in response to the input of this signal to the contact BP8. That is, the signal level of the signal line HREQ is set to H level (T9).

  The communication performed from time T6 to time T9 described above is one hot line communication. As described above, in one hot line communication, one lens position data signal 503 is transmitted by the lens control unit 203 and the second lens side communication unit 218. The contacts LP7, LP8, BP7, and BP8 used for hotline communication are contacts through which asynchronous signals that are not synchronized with other clock signals are transmitted. That is, the contacts LP7 and BP7 are contacts through which asynchronous signals (signal level HREQ signal level / H (High) level or L (Low) level) are transmitted, and the contacts LP8 and BP8 are asynchronous signals (signal line HANS). Signal level / H (High) level or L (Low) level).

  Note that the command data communication and the hotline communication can be executed simultaneously or partially in parallel. That is, one of the lens side first communication unit 217 and the lens side second communication unit 218 can communicate with the camera body 100 even when the other is communicating with the camera body 100. is there.

(Explanation of zoom control)
The body control unit 103 is configured to be able to transmit a zoom drive command to the lens control unit 203 by command data communication. The zoom drive command is a command including at least a focal length. The ROM 215 in the interchangeable lens 200 stores a table indicating the correspondence between the position on the optical axis O of the zoom lens 210b and a predetermined focal length. Upon receiving this zoom drive command, the lens control unit 203 refers to the above table and acquires the position of the zoom lens 210b corresponding to the focal length specified by the zoom drive command. Then, the zoom drive unit 212 is controlled so that the zoom lens 210b is driven to the acquired position. As a result, the focal length of the imaging optical system 210 becomes the focal length specified by the zoom drive command.

  When the photographer operates the zoom operation member (slide switch 219) of the interchangeable lens 200, the lens control unit 203 causes the position information (in other words, the position of the slide switch 219 according to the operation to the zoom operation member (slide switch 219)). Then, information for designating the zooming direction and zooming speed of the zoom lens) is transmitted to the body control unit 103 on the camera body side via the command data communication system. Based on the position information of the slide switch 219 received from the interchangeable lens 200, the body control unit 103 generates zoom command data (zoom drive command) indicating a zooming instruction for the interchangeable lens 200. Specifically, the camera body 100 is previously provided with table information corresponding to the position information of the zoom operation member (slide switch 219). This table information correlates the operation position of the slide switch 219 with the contents of commands for the zoom lens 210b (zooming directions such as tele and wide directions and zooming speeds such as high speed, medium speed and low speed). . And the body control part 103 will transmit the zoom drive command which should be transmitted to the interchangeable lens 200 to the lens control part 203 using a command data communication system.

  FIG. 6 is a diagram showing the positional relationship between the variable magnification lens 210b and the focus lens 210c. Curves L0 to L4 shown in FIG. 6 represent a zoom position corresponding to a specific shooting distance and a position on the optical axis of the focus lens 210c (a focusing lens position focused on each shooting distance). It is. The horizontal axis corresponds to the zoom position, and the vertical axis corresponds to the position (focusing lens position) on the optical axis O of the focus lens 210c. The zoom position is a discrete position that is set in advance in the interchangeable lens 200 and is a target to which the body control unit 103 moves the zoom lens 210b. The lens control unit 203 can acquire the position of the zoom lens 210b more finely than the zoom position shown in FIG.

  A predetermined focal length corresponds to each zoom position indicated by an integer of 0 to 5 in FIG. When the body control unit 103 transmits a zoom drive command, the zoom lens 210b selects a zoom position corresponding to the focal length specified by the zoom drive command from the zoom positions indicated by numerical values 0 to 5 in FIG. . Then, the zoom lens 210b is driven to a position on the optical axis O corresponding to the zoom position.

  Since the imaging optical system 210 of the present embodiment is a so-called varifocal optical system, as shown in FIG. 6, in order to keep the photographing distance constant when the variable magnification lens 210b is driven, It is necessary to drive the focus lens 210c according to the drive. For example, in FIG. 6, the curve L0 represents the position of the focus lens 210c corresponding to the shooting distance at infinity. Similarly, curves L1, L2, L3, and L4 represent the positions of the focus lens 210c corresponding to specific shooting distances (for example, 6 m, 3 m, 1 m, 50 cm, etc.) in order from the infinity side.

  When the zoom position is 1, if the focus lens 210c is at the position represented by P (0, 1) in FIG. 6, the imaging distance of the imaging optical system 210 is infinite. That is, the imaging optical system 210 is in a state in which a subject located at infinity is in focus. In FIG. 6, points corresponding to the mth shooting distance and the kth zoom position are represented in the form of P (m, k). Similarly, in the following description, a point corresponding to the shooting distance m and the zoom position k is expressed as P (m, k).

  When the zoom lens 210b is driven so that the zoom position becomes larger than 1, the focus lens 210c must be driven along the curve L0 in order to keep the photographing distance at infinity. For example, when the zoom position is 3, when the zoom position is 3, the focus lens 210c is at the position P (0,3) so that the focus lens 210c is at the position P (0,2) when the zoom position is 2. Thus, the focus lens 210c must be driven.

  The ROM 215 in the interchangeable lens 200 stores discrete points on the curves L0 to L4 shown in FIG. Specifically, the coordinates of points corresponding to the zoom positions of the curves L0 to L4 and 0 to 5 (points indicated in the form of P (m, k) in FIG. 6) are stored together with the shooting distance of the curve. ing. That is, the ROM 215 stores the position (focusing lens position) of the focus lens 210c corresponding to each of a plurality of shooting distances for each of the positions of the plurality of zoom lenses 210b. In the following description, the position of the focus lens 210c stored in the ROM 215 is referred to as position information (or simply position information) of the focus lens 210c.

  Note that FIG. 6 shows curves L0 to L4 corresponding to five shooting distances and six zoom positions 0 to 5, respectively, but this is a part of the position information stored in the ROM 215 for explanation. This is only shown, and actually, position information corresponding to a larger number of shooting distances and zoom positions is stored.

  Hereinafter, drive control of the variable power lens 210b by the lens control unit 203 will be described. When driving the variable power lens 210b, the lens control unit 203 performs so-called zoom tracking that drives the focus lens 210c in parallel so that the photographing distance is maintained.

  FIG. 7 is an enlarged view of a part of FIG. The zoom tracking will be described with reference to FIG. In FIG. 7, the positions of the zoom lens 210b corresponding to the zoom positions k, k + 1, and k + 2 are represented by Qk, Qk + 1, and Qk + 2, respectively.

  In FIG. 7, when the zoom drive command is received by the lens side first communication unit 217, it is assumed that the zoom position is k and the position of the focus lens 210c is Px. In zoom tracking control, the lens control unit 203 first calculates the position Px + 1 of the focus lens 210c corresponding to the same shooting distance at the next zoom position k + 1 by the following equation (1).

  The above equation (1) is a two-point interpolation equation for determining the position Px + 1 so that the ratio of R3 and R4 in FIG. 7 is equal to the ratio of R1 and R2.

  In this way, the target position Px + 1 to which the focus lens 210c should be moved at the next zoom position k + 1 is obtained. Next, the lens controller 203 drives the driving speed Vz of the zoom lens 210b, the driving amount (Qk + 1) −Qk of the zooming lens 210b from the zoom position k to k + 1, and the driving amount (Pk + 1) of the focus lens 210c in the same section. ) -Pk, the driving speed Vf of the focus lens 210c is calculated by the following equation (2).

  The lens control unit 203 drives the zoom lens 210b in parallel at the driving speed Vz and the focus lens 210c in parallel at the driving speed Vf calculated by the above equation (2) during the zoom positions k to k + 1. Then, the focal length of the imaging optical system 210 is changed while keeping the photographing distance constant. When the next zoom position k + 1 is reached, the lens control unit 203 performs the same calculation again for the next zoom position k + 2, and drives the zoom lens 210b and the focus lens 210c in the same manner. That is, the lens control unit 203 drives the variable power lens 210b and the focus lens 210c along the locus Lp shown in FIG.

(Explanation of focus control)
The body control unit 103 of the present embodiment transmits an absolute position driving command (hereinafter simply referred to as an absolute position driving command) of the focus lens 210c to the lens control unit 203 by command data communication. The absolute position drive command is a command for instructing to drive the focus lens 210c to an absolute position expressed with reference to the position of the focus lens 210c corresponding to infinity.

  The focus lens 210c is not driven relatively by designating the drive amount from the current position of the focus lens 210c, but from a reference position (a position corresponding to infinity) determined regardless of the current position of the focus lens 210c. This is a command for instructing the drive destination of the focus lens 210c by the distance (absolute position), and is therefore called an absolute position drive command. For example, when an absolute position driving command specifying a numerical value of “100” as the absolute position is received by the lens control unit 203, the lens control unit 203 drives the focus lens 210c to a position separated by 100 from the current position. Instead, the focus lens 210c is driven to a position separated by 100 from a position corresponding to infinity.

  The body control unit 103 sends the absolute position drive command to the lens control unit when, for example, automatic focus adjustment is performed by the photographer's operation or when the photographer operates a focus operation member (not shown) in the manual focus mode. Then, the focus lens 210c is driven (the focus position is changed).

  When the absolute position driving command is received by the lens-side first communication unit 217, the lens control unit 203 first sets the infinity position corresponding to the current zoom position (the position of the focus lens 210c corresponding to infinity) to the ROM 215. Get from. Referring to FIG. 6, the coordinates of the point corresponding to the current zoom position (the position of the focus lens 210c) from each point (P (0,0), P (0,1),...) Existing on the curve L0. To get. Then, the drive target position of the focus lens 210c corresponding to the absolute position is calculated by adding the absolute position specified by the absolute position drive command to the position. The lens control unit 203 controls the focus driving unit 214 to drive the focus lens 210c to the drive target position calculated in this way.

  By the way, when the absolute position drive command is transmitted from the body control unit 103 during driving of the zoom lens 210b, the control described above cannot be performed for the reason described below. First, during the driving of the variable power lens 210b, the variable power lens 210b does not always exist at a predetermined zoom position (a position indicated by an integer of 0 to 5 in FIG. 6). When the zoom lens 210b is located at a position other than any zoom position, the infinity position corresponding to the position cannot be acquired from the ROM 215. Next, the fact that the zoom lens 210b is being driven means that the position of the zoom lens 210b changes from moment to moment, so the position of the focus lens 210c corresponding to infinity also changes over time. End up. Therefore, even if the focus lens 210c is driven to the drive target position calculated when the absolute position drive command is received, when the focus lens 210c reaches the drive target position, the drive target position is designated by the absolute position drive command. The position is different from the absolute position.

  Therefore, when the absolute position drive command is received, the lens control unit 203 of this embodiment first determines whether or not the variable power lens 210b is being driven. When it is determined that the zoom lens 210b is being driven, the focus lens 210c is driven to a correction position where the change in the drive target position due to the driving of the zoom lens 210b is corrected.

  Hereinafter, the processing of the lens control unit 203 when an absolute position drive command is received during driving of the zoom lens 210b will be described with reference to the flowchart of FIG.

  FIG. 8 is a flowchart of processing upon reception of an absolute position drive command during driving of the variable power lens 210b. First, in step S100, the lens control unit 203 determines whether or not the absolute position drive command transmitted from the camera body 100 is received by the lens-side first communication unit 217. When the absolute position driving command is received, the process proceeds to step S110.

  In step S110, the lens control unit 203 calculates an infinite position (the position of the focus lens 210c corresponding to infinity) corresponding to the current position of the variable magnification lens 210b. This calculation will be described with reference to FIG. 9 in which a part of FIG. 6 is enlarged. In FIG. 9, it is assumed that the absolute position drive command is received by the lens-side first communication unit 217 when the zoom drive unit 212 is driving the zoom lens 210b in the direction from the zoom position k to k + 1. I do. That is, the lens control unit 203 performs zoom tracking along the locus Lp. Further, the position of the zoom lens 210b at the time of receiving the absolute position driving command is represented by Qq, and the position of the focus lens 210c is represented by Pa. The lens control unit 203 calculates the infinity position P (0, q) corresponding to the current position Qq of the zoom lens 210b by the following equation (3).

  In step S120, the lens control unit 203 calculates the drive target position Pb of the focus lens 210c by adding the absolute position R7 designated by the absolute position drive command to the calculated infinity position P (0, q). To do. That is, Pb = P (0, q) + R7. In step S130, the lens control unit 203 calculates a drive locus of the focus lens 210c having the same shooting distance as the drive target position Pb calculated in step S120.

  FIG. 10 is an enlarged view of a part of FIG. In step S120, the lens control unit 203 first determines from the position information stored in the ROM 215 four points (points P (n, k), P (n + 1, k), P (n + 1 in FIG. 10) surrounding the drive target position Pb. , K + 1), and P (n, k + 1)). Then, from these four points and the current position Qq of the variable magnification lens 210b, two points P (n, q) and P (n + 1, q corresponding to the position Qq on the curves Ln and Ln + 1 before and after the drive target position Pb. ) Is calculated by the following equations (4) and (5).

  Thereafter, the lens control unit 203 calculates the lens locus Ls in the section from the position Qk to Qk + 1 based on the relative position of Pb in the section from P (n, q) to P (n + 1, q). This lens locus Ls is, for example, a position Py corresponding to Pb in a section from P (n, k) to P (n + 1, k), and Pb in a section from P (n, k + 1) to P (n + 1, k + 1). The corresponding position Py + 1 can be calculated from the following equations (6) and (7), respectively, and can be obtained by calculating a straight line connecting Py and Py + 1.

  The lens control unit 203 then moves between the curves Ln and Ln + 1 at a position where the position of the focus lens 210c is equal to the ratio of Pb−P (n, q) and P (n + 1, q) −Pb, that is, in FIG. The focus lens 210c is driven so as to be on the locus Ls shown.

  In step S140, the lens control unit 203 calculates the focus lens drive target position Ptgt at the current zoom lens position. Here, a case where the current position of the zoom lens is Qr will be described. First, the lens control unit 203 uses the expressions (4) and (5) to change the current position of the zoom lens to points P (n, r) and P (n + 1, r) on the curves Ln and Ln + 1 corresponding to Qr. ) Next, the focus lens drive target position Ptgt corresponding to the current zoom lens position Qr, that is, the ratio of P (n + 1, q) -Pb to Pb-P (n, q) is P (n + 1, r). A position that is equal to the ratio of -Pc and Pc-P (n, r) is calculated by the following equation (8).

  In step S150, the lens control unit 203 predicts the predicted target position Pnext after a predetermined time Ts (for example, 25 milliseconds) has elapsed.

  FIG. 11 is a diagram showing the drive target position Pnext when the predetermined time Ts has elapsed from the current focus lens drive position, and driving when the predetermined time Ts has elapsed from the position Pa where the absolute position drive command is received. The target position is indicated as Pc. In FIG. 11, unlike FIG. 10 or the like, the horizontal axis represents time, and the vertical axis represents the position of the focus lens 210c.

  First, the lens control unit 203 uses the inclination of the lens locus Ls calculated in step S130 to obtain the in-focus position moving speed Va in FIG.

When Va obtained by the above equation is multiplied by a predetermined time Ts (Vf × Ts), the change amount of the drive target position after the predetermined time Ts can be obtained. As a result, the lens control unit 203 calculates the drive target position Pnext at the time when the predetermined time Ts has elapsed from the following equation (10).
Pnext = Ptgt + Va × Ts (10)

In step S160, the lens control unit 203 calculates a driving speed Vf for causing the focus lens 210c to reach the predicted target position Pnext from the current position Pcur after the time Ts has elapsed. The driving speed Vf can be calculated by the following equation (11).
Vf = (Pnext−Pcur) / Ts (11)

  In step S170, the lens control unit 203 resets a predetermined timer and starts measuring time by the timer. The lens control unit 203 updates the driving speed of the focus lens 210c every time this timer reaches a predetermined time Tc shorter than the above-described Ts time (details will be described later). In step S180, the lens control unit 203 causes the focus driving unit 214 to start driving the focus lens 210c at the driving speed Vf calculated in step S160.

  In step S <b> 190, the lens control unit 203 determines whether or not the lens-side first communication unit 217 has received an absolute position drive command again. If an absolute position drive command has been received, the lens control unit 203 returns to step S110 and calculates the drive locus of the focus lens 210c again. If an absolute position drive command has not been received, the process proceeds to step S200.

  In step S200, the lens control unit 203 determines whether or not the zoom lens 210b has reached the next zoom position. For example, in FIG. 10, if the zoom position k + 1 has been reached (the zoom lens 210b has reached the position Qk + 1), the lens control unit 203 has reached the next zoom position (the zoom position has changed). ). If the zoom position has changed, the lens locus Ls needs to be calculated again, so the lens control unit 203 executes the processing from step S130 again. If the zoom position has not changed, the process proceeds to step S210.

  In step S210, the lens control unit 203 determines whether or not the driving speed of the variable power lens 210b has changed. For example, when the photographer changes the operation amount of the slide switch 219, the body control unit 103 transmits a zoom drive command corresponding to a new zooming speed (high speed, medium speed, low speed, etc.) to the lens control unit 203. As a result, the driving speed of the zoom lens 210b changes. When the driving speed of the variable power lens 210b changes, the inclination of the lens locus Ls shown in FIG. 11 changes, so it is necessary to calculate the lens locus Ls again. Therefore, when the driving speed of the variable power lens 210b changes, the lens control unit 203 executes the processing from step S130 again. If the driving speed of the zoom lens 210b has not changed, the process proceeds to step S220.

  In step S220, the lens control unit 203 determines whether zoom driving has been completed. That is, it is determined whether or not both the zoom lens 210b and the focus lens have reached the final target position. If the zoom drive continues, the process proceeds to step S230. On the other hand, when the zoom operation is completed, the processing in FIG. 8 is terminated.

  In step S230, the lens control unit 203 determines whether or not the predetermined time Tc has elapsed since the last execution of step S170, that is, whether or not the timer has reached the predetermined time Tc. This predetermined time Tc is a time slightly shorter than the above-mentioned predetermined time Ts (for example, a time shorter by 5 milliseconds). If the predetermined time Tc has elapsed from step S170, the process returns to step S140, and the lens control unit 203 calculates the in-focus position after the predetermined time Ts again. Then, the drive speed of the focus lens 210c necessary for reaching the in-focus position is calculated, and the focus lens 210c is driven at the drive speed. On the other hand, if the predetermined time Tc has not elapsed in step S230, the processing from step S190 is re-executed. As described above, the lens control unit 203 of the present embodiment executes the processing of steps S130 to S180 every time the predetermined time Tc elapses, and updates the driving speed of the focus lens 210c. As a result, the focus lens 210c gradually approaches the target lens locus Ls.

  As described above, the drive speed of the focus lens 210c is updated every predetermined time Tc shorter than the predetermined time Ts because the focus lens 210c reaches the drive target position and then the drive speed is rapidly changed. This is to suppress the shoot. Hereinafter, this point will be described with reference to FIG. If the focus lens 210c is driven at the drive speed Va described above, the focus lens 210c theoretically moves from the position Pa to the predicted target position Pc. After reaching the predicted target position Pc, the focus lens 210c needs to be driven along the lens locus Ls. However, as is apparent from FIG. 11, in order to perform such lens driving, it is necessary to rapidly change the driving speed of the focus lens 210c at the predicted target position Pc. Normally, when a linear motor such as a voice coil motor is employed as the actuator of the focus driving unit 214, it is difficult to configure such that such a rapid speed change is possible.

  Therefore, in this embodiment, the driving speed of the focus lens 210c is updated every time Tc shorter than the predetermined time Ts so that the focus lens 210c gradually approaches the target lens locus Ls. This is shown in FIG. The focus lens 210c driven from the lens position Pa toward the predicted target position Pc reaches the position Pd when the time Tc has elapsed. From here, the drive speed is changed so that it is driven toward the predicted target position Pe when the predetermined time Ts has passed. In addition, since the driving speed cannot be changed suddenly even at the position Pd, it actually moves to the new predicted target position Pe after passing through the position Pd.

According to the camera system according to the first embodiment described above, the following operational effects can be obtained.
(1) The imaging optical system 210 includes a variable power lens 210b and a focus lens 210c, which can be driven in the direction of the optical axis O and are disposed on the same optical axis O. The imaging distance and the position of the focus lens 210c Is a varifocal optical system in which the relationship with the variable power lens 210b changes according to the position of the zoom lens 210b. The ROM 215 stores position information regarding the position of the focus lens 210c corresponding to each of a plurality of shooting distances for each of a plurality of positions of the zoom lens 210b. The first lens-side communication unit 217 receives from the camera body 100 an absolute position driving command for driving the focus lens 210c to a predetermined absolute position expressed with reference to the infinity position. The lens control unit 203 calculates the drive target position of the focus lens 210c corresponding to a predetermined absolute position using the current position of the variable magnification lens 210b and the position information of the ROM 215, and the focus drive unit 214 reaches the drive target position. The focus lens 210c is driven. However, when it is determined that the variable power lens 210b is being driven when the absolute position drive command is received, a predicted target position that predicts a change in the drive target position due to the driving of the variable power lens 210b is calculated, The focus lens 210c is driven to this predicted target position. Since this is done, the focus lens 210c can be correctly driven even while the variable power lens 210b is being driven.

(2) When the position of the focus lens 210c corresponding to the infinity position based on the absolute position drive command and the current position of the zoom lens 210b is not included in the position information of the ROM 215, the lens control unit 203 The drive target position is calculated by an interpolation calculation using the current position of the zoom lens 210b and position information. Thus, even when the zoom lens 210b is between the predetermined zoom positions, the drive target position of the focus lens 210c can be correctly calculated.

(3) The lens control unit 203 calculates the drive target position of the focus lens 210c corresponding to the position of the zoom lens 210b after the predetermined time Ts has elapsed as a predicted target position, and the focus lens 210c is at the predicted target position. The focus driving unit 214 is controlled to be driven. Since it did in this way, the focus lens 210c can be correctly driven to the position which considered the time change of the focal distance (position of the variable magnification lens 210b).

(4) The lens control unit 203 predicts every time a predetermined time Tc shorter than the predetermined time Ts elapses, the zoom lens 210b reaches the next zoom position, or the driving speed of the zoom lens 210b changes. The target position is calculated, and the focus driving unit 214 is controlled so that the focus lens 210c is driven to the predicted target position. Since this is done, the focus lens 210c can be accurately guided to the correct lens locus.

  The following modifications are also within the scope of the present invention, and one or a plurality of modifications can be combined with the above-described embodiment.

(Modification 1)
The present invention can also be applied to a camera system different from that shown in FIG. For example, the present invention can be applied to a so-called single-lens reflex camera system including a quick return mirror.

(Modification 2)
The calculations performed by the lens control unit 203 during zoom tracking, calculation of the drive target position, correction calculation, and the like may be different from those described in the above-described embodiments. For example, each position may be calculated by a method other than two-point interpolation.

(Modification 3)
The reference position for the absolute position drive command may be a position other than the infinite position corresponding to infinity. For example, the position of the focus lens 210c corresponding to the closest end may be used as a reference, or a position other than that may be used.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

DESCRIPTION OF SYMBOLS 1 ... Camera system, 100 ... Camera body, 101 ... Body side mount part, 102, 202 ... Holding part, 103 ... Body control part, 117 ... Body side 1st communication part, 118 ... Body side 2nd communication part, 200 ... Interchangeable lens, 201 ... Lens side mount unit, 203 ... Lens control unit, 210 ... Image forming optical system, 210b ... Variable lens, 210c ... Focus lens, 211 ... Aperture, 212 ... Zoom drive unit, 213 ... Aperture drive unit, 214... Focus drive unit, 215... ROM, 217... Lens side first communication unit, 218.

Claims (7)

Each includes a variable power lens and a focus lens arranged on the same optical axis that can be driven in the optical axis direction, and the relationship between the shooting distance and the position of the focus lens changes according to the position of the variable power lens. With focal optics,
Storage means for storing position information regarding the position of the focus lens corresponding to a plurality of shooting distances for each of the plurality of positions of the zoom lens;
Mounting means for detachably attaching the camera body;
Receiving means for receiving, from the camera body, a command to drive the focus lens to a predetermined absolute position represented with reference to a position corresponding to a predetermined shooting distance;
First calculation means for calculating a drive target position of the focus lens corresponding to the predetermined absolute position using the current position of the zoom lens and the position information;
Drive means for driving the focus lens to the drive target position calculated by the first calculation means;
Determining means for determining whether or not the zoom lens is being driven when the command is received by the receiving means;
A second calculation unit that calculates a predicted target position that predicts a change in the drive target position due to the driving of the variable power lens when the determination unit determines that the variable power lens is being driven;
The interchangeable lens, wherein the drive unit drives the focus lens to the predicted target position when the determination unit determines that the variable power lens is being driven. The interchangeable lens according to claim 1,
When the position information does not include a position of the focus lens corresponding to a predetermined shooting distance based on the command and a current position of the variable magnification lens, the first calculation unit includes the variable magnification lens. The drive target position is calculated by an interpolation calculation using the current position and the position information. The interchangeable lens according to claim 1 or 2,
The interchangeable lens, wherein the second calculation means calculates, as the predicted target position, a drive target position of the focus lens corresponding to the position of the zoom lens after the first predetermined time has elapsed. The interchangeable lens according to claim 3,
The interchangeable lens, wherein the second calculation means calculates the predicted target position after the first predetermined time elapses every time a second predetermined time shorter than the first predetermined time elapses. The interchangeable lens according to claim 3 or 4,
The interchangeable lens, wherein the second calculation means calculates the predicted target position after the first predetermined time elapses every time the zoom lens reaches a predetermined position. In the interchangeable lens as described in any one of Claims 3-5,
The interchangeable lens, wherein the second calculating means calculates the predicted target position after the first predetermined time has passed each time the driving speed of the variable power lens changes. In the interchangeable lens as described in any one of Claims 1-6,
The interchangeable lens, wherein the predetermined shooting distance based on the command is infinity.