Accessory apparatus, image-capturing apparatus, control apparatus, lens apparatus, control method, computer program and storage medium storing computer program

The accessory apparatus provides, with an image-capturing apparatus, a notification channel used for providing a notice from the image-capturing apparatus to the accessory apparatus, a first data communication channel used for data transmission from the accessory apparatus to the image-capturing apparatus, and a second data communication channel used for data transmission from the image-capturing apparatus to the accessory apparatus. An accessory controller acquires from a timer, in response to receiving a transmission request as the notice, a first time of receiving the transmission request and acquires, in response to receiving a specific command through the second data communication channel from the image-capturing apparatus, accessory information corresponding to the first time or a second time acquired based on the first time. The accessory controller transmits the accessory information to the image-capturing apparatus through the first data communication channel.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image-capturing apparatus (hereinafter referred to as “a camera body”) and an accessory apparatus such as an interchangeable lens, which are communicable with each other. The present invention further relates to an image-capturing apparatus performing a follow shot assist process.

Description of the Related Art

In an accessory-interchangeable camera system including a camera body to which an accessory apparatus is detachably attachable, the camera body and the accessory apparatus communicate with each other for controlling the accessory apparatus from the camera body and for providing, from the accessory apparatus to the camera body, data required for controlling the accessory apparatus. In particular, when an interchangeable lens is used for capturing a moving image to be recorded, or a live-view moving image to be displayed, smooth lens control in synchronization with image-capturing periods is required, so that it is necessary to synchronize image-capturing times in the camera body with control times in the interchangeable lens. Thus, the camera body is required to complete receipt of the data from the interchangeable lens, and transmission of various commands and requests to the interchangeable lens in one image-capturing period.

However, an increase of an amount of the data to be received by the camera body from the interchangeable lens and a reduction of the image-capturing period (that is, an increase of a frame rate) require a large data amount communication in a shorter time.

On the other hand, a camera system is provided that performs, when a user performs a follow shot of a moving object, a follow shot assist process by moving an image-stabilizing lens depending on an angular velocity detected by a gyro sensor included in an interchangeable lens, and on a movement amount of an object image on an image sensor included in a camera body. In order to perform a good follow shot assist process, it is necessary to accurately synchronize a time point at which the camera body calculates the movement amount of the object on the image sensor with a time point at which the interchangeable lens detects the angular velocity.

Japanese Patent No. 5247859 discloses a camera system that notices a time point of a vertical synchronization signal to an interchangeable lens by keeping a signal level of a communication terminal at a predetermined level for a predetermined time period or more, and then changing the signal level of the communication terminal in synchronization with the vertical synchronization signal.

However, in the camera system disclosed in Japanese Patent No. 5247859, in a case of requiring a large data amount communication in a short time, it is difficult to acquire the predetermined time period for which the signal level of the communication terminal is kept at the predetermined level. Furthermore, there is a case where another communication for transmitting, for example, a focus drive command to the interchangeable lens inhibits a well-timed control of the signal level.

In addition, Japanese Patent Laid-Open No. 2006-317848 discloses a method of enabling a good follow shot by detecting a difference between a moving velocity of an object and a panning speed of a lens-integrated camera, and by correcting the difference using an image-stabilizing function. Japanese Patent Laid-Open No. 2015-161730 discloses a method of improving a detection accuracy of a moving speed of an object by changing an output time point of a shake detector, that is, a detection time point of an angular velocity depending on an exposure time period and a frame rate to match the detection time point of the angular velocity with a detection time point of a motion vector of the object (object image).

However, the methods disclosed in Japanese Patent Laid-Open Nos. 2006-317848 and 2015-161730 are used not for lens-interchangeable camera systems, but only for lens-integrated cameras. In order to improve a performance of the follow shot assist process in the lens-interchangeable camera system, it is necessary to properly manage the detection time point of the motion vector or the moving velocity of the object and that of the angular velocity.

SUMMARY OF THE INVENTION

The present invention provides an accessory apparatus and an image-capturing apparatus capable of performing calculation, control and other processes in a lens-interchangeable image-capturing system by using data accurately synchronized with each other between the accessory apparatus and the image-capturing apparatus. The present invention further provides a control apparatus and others capable of improving a performance of a follow shot assist process.

The present invention provides as an aspect thereof an accessory apparatus detachably attachable to an image-capturing apparatus. The accessory apparatus includes an accessory communicator configured to provide, with the image-capturing apparatus, three channels that are a notification channel used for providing a notice from the image-capturing apparatus to the accessory apparatus, a first data communication channel used for data transmission from the accessory apparatus to the image-capturing apparatus, and a second data communication channel used for data transmission from the image-capturing apparatus to the accessory apparatus. The accessory apparatus further includes an accessory controller configured to perform the data communication with the image-capturing apparatus through the accessory communicator and configured to acquire accessory information changing with time, and a timer configured to count time. The accessory controller is configured to acquire from the timer, in response to receiving a transmission request as the notice from the image-capturing apparatus through the notification channel, a first time of receiving the transmission request, acquire, in response to receiving a specific command through the second data communication channel from the image-capturing apparatus, the accessory information corresponding to the first time or a second time acquired based on the first time, and transmit the accessory information to the image-capturing apparatus through the first data communication channel.

The present invention provides as another aspect thereof an image-capturing apparatus to which an accessory apparatus is detachably attachable. The image-capturing apparatus includes a camera communicator configured to provide, with the accessory apparatus, three channels that are a notification channel used for providing a notice from the image-capturing apparatus to the accessory apparatus, a first data communication channel used for data transmission from the accessory apparatus to the image-capturing apparatus, and a second data communication channel used for data transmission from the image-capturing apparatus to the accessory apparatus. The image-capturing apparatus further includes and a camera controller configured to perform data communication with the accessory apparatus through the camera communicator. The camera controller is configured to provide a transmission request as the notice to the accessory apparatus through the notification channel, transmit, to the accessory apparatus through the first data communication channel, a specific command for causing the accessory apparatus to acquire accessory information corresponding to a first time of receiving the transmission request or corresponding to a second time acquired based on the first time, the accessory information changing with time, and receive the accessory information corresponding to the first or second time from the accessory apparatus through the second data communication channel.

The present invention provides as yet another aspect thereof an image-capturing system including the above accessory and image-capturing apparatuses.

The present invention provides as still another aspect thereof a control method of controlling an accessory apparatus detachably attachable to an image-capturing apparatus and configured to provide, with the image-capturing apparatus, three channels that are a notification channel used for providing a notice from the image-capturing apparatus to the accessory apparatus, a first data communication channel used for data transmission from the accessory apparatus to the image-capturing apparatus, and a second data communication channel used for data transmission from the image-capturing apparatus to the accessory apparatus. The control method includes the step of causing the accessory apparatus to acquire, in response to receiving a transmission request as the notice from the image-capturing apparatus through the notification channel, a first time of receiving the transmission request, the step of causing the accessory apparatus to acquire, in response to receiving a specific command through the second data communication channel, the accessory information corresponding to the first time or a second time acquired based on the first time, and the step of causing the accessory apparatus to transmit the accessory information to the image-capturing apparatus through the first data communication channel.

The present invention provides as yet still another aspect thereof a control method of controlling an image-capturing apparatus to which an accessory apparatus is detachably attachable and that is configured to provide, with the accessory apparatus, three channels that are a notification channel used for providing a notice from the image-capturing apparatus to the accessory apparatus, a first data communication channel used for data transmission from the accessory apparatus to the image-capturing apparatus and a second data communication channel used for data transmission from the image-capturing apparatus to the accessory apparatus. The control method includes the step of causing the image-capturing apparatus to provide a transmission request as the notice to the accessory apparatus through the notification channel, the step of causing the image-capturing apparatus to transmit, to the accessory apparatus through the first data communication channel, a specific command for causing the accessory apparatus to acquire accessory information corresponding to a first time of receiving the transmission request or corresponding to a second time acquired based on the first time, the accessory information changing with time, and the step of causing the image-capturing apparatus to receive the accessory information corresponding to the first or second time from the accessory apparatus through the second data communication channel.

The present invention provides as further another aspect thereof a control apparatus (image-capturing apparatus) including a motion vector detector configured to detect a motion vector in a first time period, a calculator configured to set, depending on the first time period, an angular velocity detection time period in which a first angular velocity is detected by an angular velocity detector, and a communicator configured to transmit the angular velocity detection time period and first ID information corresponding to the first time period in relation to each other, and receive the first angular velocity detected in the angular velocity detection time period and second ID information corresponding to the first angular velocity in relation to each other. The calculator is configured to calculate an angular velocity of an object, when the first ID information and the second ID information are identical to each other, by using the motion vector detected in the first time period corresponding to the first ID information and the first angular velocity corresponding to the second ID information.

The present invention provides as yet another aspect thereof a control apparatus (lens apparatus) including a communicator configured to receive an angular velocity detection time period in which a first angular velocity is detected and first ID information in relation to each other, the first ID information corresponding to a first time period that is a motion vector detection time period in which a motion vector is detected, the angular velocity detection time period being set depending on the first time period, and an angular velocity detector configured to detect the first angular velocity in the angular velocity detection time period. The communicator is configured to transmit the first angular velocity and second ID information corresponding to the first angular velocity in relation to each other when the first ID information and the second ID information are identical to each other.

The present invention provides as still another aspect thereof a control method including the step of detecting a motion vector in a first time period, the step of setting, depending on the first time period, an angular velocity detection time period in which a first angular velocity is detected by an angular velocity detector, the step of transmitting the angular velocity detection time period and first ID information corresponding to the first time period in relation to each other, the step of receiving the first angular velocity detected in the angular velocity detection time period and second ID information corresponding to the first angular velocity in relation to each other; and the step of calculating an angular velocity of an object, when the first ID information and the second ID information are identical to each other, by using the motion vector detected in the first time period corresponding to the first ID information and the first angular velocity corresponding to the second ID information.

The present invention provides as yet still another aspect thereof a control method including the step of receiving an angular velocity detection time period in which a first angular velocity is detected and first ID information in relation to each other, the first ID information corresponding to a first time period that is a motion vector detection time period in which a motion vector is detected, the angular velocity detection time period being set depending on the first time period, the step of detecting the first angular velocity in the angular velocity detection time period, and the step of transmitting the first angular velocity and second ID information corresponding to the first angular velocity in relation to each other when the first ID information and the second ID information are identical to each other.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described below with reference to the accompanied drawings.

FIG. 1illustrates a configuration of an image-capturing system (hereinafter referred to as “a camera system”) including a camera body200as an image-capturing apparatus and an interchangeable lens100as an accessory apparatus according to a first embodiment (Embodiment 1) of the present invention.

The camera body200and the interchangeable lens100transmit control commands and internal information to each other via their communicators described later.

The communicators are compatible with various communication methods and switch their communication formats to the same one in synchronization with each other depending on types of data to be communicated and the purposes of their communication. This enables selecting an optimum communication format for each of various situations. First, description will be made of specific configurations of the interchangeable lens100and the camera body200. The interchangeable lens100and the camera body200are mechanically and electrically connected with each other via a mount300including a coupling mechanism. The interchangeable lens100receives power supply from the camera body200via a power source terminal (not illustrated) provided in the mount300and supplies, to various actuators and a lens microcomputer described later, power sources necessary for their operations. The interchangeable lens100and the camera body200communicate with each other via communication terminals (illustrated inFIG. 2) provided in the mount300.

The interchangeable lens100includes an image-capturing optical system. The image-capturing optical system includes, from an object (OBJ) side, a field lens101, a magnification-varying lens102for variation of magnification, a stop unit (aperture)114for light amount control, an image-stabilizing lens103for image blur correction and a focus lens104for focusing.

The magnification-varying lens102and the focus lens104are respectively held by lens holders105and106. The lens holders105and106are guided by guide bars (not illustrated) movably in an optical axis direction in which an optical axis (illustrated by a broken line) of the image-capturing optical system extends and are driven in the optical axis direction respectively by stepping motors107and108. The stepping motors107and108rotate in synchronization with drive pulses and respectively move the magnification-varying lens102and the focus lens104.

The image-stabilizing lens103is moved in a direction orthogonal to the optical axis of the image-capturing optical system to reduce image blur caused by user's hand jiggling or the like.

The lens microcomputer111as an accessory controller controls various operations in the interchangeable lens100. The lens microcomputer111includes a lens communicator112and receives, via the lens communicator112, control commands transmitted from the camera body200and transmission requests output therefrom. The lens microcomputer111performs various lens controls corresponding to the control commands and transmits lens data corresponding to the transmission requests via the lens communicator112.

The lens microcomputer111performs operations relating to the communication with the camera body200(that is, with a camera microcomputer described later) according to a lens communication control program as a computer program.

In addition, the lens microcomputer111outputs, in response to a zoom command and a focus drive command among the control commands, a zoom drive signal and a focus drive signal to a zoom driver119and a focus driver120to cause them to drive the stepping motors107and108, thereby performing a zoom process to control a magnification variation operation by the magnification-varying lens104and an AF (autofocus) process to control a focus operation by the focus lens104.

The interchangeable lens100is provided with a manual focus ring (not illustrated) that is rotationally operable by a user and a focus encoder (not illustrated) for detecting a rotational operation amount of the manual focus ring. The lens microcomputer111causes the focus driver120to drive the stepping motor108by a drive amount corresponding to the rotational operation amount of the manual focus ring detected by the focus encoder, thereby performing MF (manual focus).

The stop unit114includes stop blades114aand114b.An open-and-close state of the stop blades114aand114bis detected by a hall element115, and a detection result thereof is input to the lens microcomputer111through an amplifier122and an A/D converter123. The lens microcomputer111outputs, depending on the input signal from the A/D converter123, a stop drive signal to a stop driver121so as to cause the stop driver121to drive a stop actuator113, thereby controlling a light amount control operation of the stop unit114.

The interchangeable lens100further includes a shake sensor (hereinafter referred to as “a gyro sensor”)129constituted by a vibration gyro or the like. The lens microcomputer111drives an image-stabilizing actuator126constituted by a voice coil motor or the like through an image-stabilizing driver125depending on a shake (angular velocity) detected by the gyro sensor129, thereby performing an image-stabilizing process to control the movement of the image-stabilizing lens103. Moreover, the lens microcomputer111performs, when the user performs follow shot for capturing a moving object while panning the camera system, a follow shot assist process to control the movement of the image-stabilizing lens103while communicating with the camera microcomputer205as described later.

The interchangeable lens100includes a timer130as a free-run timer that counts time with microsecond accuracy. The interchangeable lens100further includes a lens memory (accessory memory)128that is constituted by a rewritable volatile memory and that temporarily stores data required for the controls performed by the lens microcomputer111. The lens microcomputer111causes the lens memory128to store the angular velocity acquired through the gyro sensor129and the time acquired by the timer130in relation to each other.

The camera body200includes an image sensor201constituted by a CCD sensor, a CMOS sensor or the like, an A/D converter202, a signal processor203, a recorder (memory)204, the camera microcomputer205and a display unit206.

The image sensor201photoelectrically converts an object image formed by the image-capturing optical system in the interchangeable lens100to output an image-capturing signal as an analog electrical signal.

The A/D converter202converts the analog image-capturing signal from the image sensor201into a digital image-capturing signal. The signal processor203performs various image processes on the digital image-capturing signal from the A/D converter123to produce a video signal. The signal processor203produces, from the video signal, focus information indicating a contrast state of the object image (that is, a focus state of the image-capturing optical system) and luminance information indicating an exposure state. The signal processor203outputs the video signal to the display unit206. The display unit206displays the video signal as a live-view image used for checking an image-capturing composition and the focus state. In addition, the signal processor203outputs the video signal to the recorder204. The recorder204records the video signal.

The signal processor203further produces a vertical synchronization signal at every time of the photoelectric conversion of the object image (charge accumulation) by the image sensor201to input the vertical synchronization signal to the camera microcomputer205. The camera microcomputer205acquires a time point at which half of a charge accumulation time period from an input time point of the vertical synchronization signal has elapsed, as a center time of the charge accumulation time period. The charge accumulation time period is an exposure time period for the image sensor201. The center time of the charge accumulation time period is hereinafter referred to as “an accumulation center time”. The signal processor203may input a signal indicating the accumulation center time to cause the camera microcomputer205to acquire the accumulation center time. The camera microcomputer205includes a timer209as a free-run timer that counts time with microsecond accuracy.

A camera memory210is constituted by a rewritable volatile memory. The camera memory210stores the digital image-capturing signal acquired from the image sensor201, the video signal produced by the signal processor203and the lens data received from the lens microcomputer111. Furthermore, the camera memory210temporarily stores data required for various control operations performed by the camera microcomputer205.

The camera microcomputer205as a camera controller controls the camera body200in response to inputs from a camera operation unit207including an image-capturing instructing switch and various setting switches (not illustrated). The camera microcomputer205transmits, in response to a user's operation of a zoom switch (not illustrated), the control command relating to the magnification-varying operation of the magnification-varying lens102to the lens microcomputer111through a camera communicator208included in the camera microcomputer205. Moreover, the camera microcomputer205transmits, through the camera communicator208, the control command relating to the light amount control operation of the stop unit114depending on the luminance information and the control command relating to the focusing operation of the focus lens104depending on the focus information. The camera microcomputer205performs operations relating to the communication with the lens microcomputer111according to a camera communication control program as a computer program.

Next, with reference toFIG. 2, description will be made of a communication circuit constituted between the camera body200(camera microcomputer205) and the interchangeable lens100(lens microcomputer111) and of the communication performed therebetween. The camera microcomputer205has a function of managing settings for the communication with the lens microcomputer111and a function of providing notices such as the transmission requests. On the other hand, the lens microcomputer111has a function of producing lens data and a function of transmitting the lens data.

The camera microcomputer205includes a camera communication interface circuit208a,and the lens microcomputer111includes a lens communication interface circuit112a.The camera microcomputer205(camera data transceiver208b) and the lens microcomputer111(lens data transceiver112b) communicate with each other through the communication terminals (illustrated by three boxes) provided in the mount300and the camera and lens communication interface circuits208aand112a.In this embodiment, the camera and lens microcomputers205and111perform three-wire asynchronous serial communication using three channels. The camera data transceiver208band the camera communication interface circuit208aconstitute the camera communicator208. The lens data transceiver112band the lens communication interface circuit112aconstitute the lens communicator112. Although, a three-wire asynchronous serial communication using three channels is used in this embodiment, other number-wire serial communication and channels are possible.

The three channels are a transmission request channel as a notification channel, a first data communication channel and a second data communication channel. The transmission request channel is used for providing the notices such as the transmission requests (transmission instructions) for the lens data and switch requests (switch instructions) for communication settings described later, from the camera microcomputer205to the lens microcomputer111. The provision of the notice through the transmission request channel is performed by switching a signal level (voltage level) on the transmission request channel between High as a first level and Low as a second level. A transmission request signal provided to the transmission request channel is hereinafter referred to as “a request-to-send signal RTS”.

The first data communication channel is used for transmitting the lens data from the lens microcomputer111to the camera microcomputer205. The lens data (accessory data) transmitted as a signal from the lens microcomputer111to the camera microcomputer205through the first data communication channel is hereinafter referred to as “a lens data signal DLC”. The second data communication channel is used for transmitting camera data from the camera microcomputer205to the lens microcomputer111. The camera data transmitted as a signal from the camera microcomputer205to the lens microcomputer111through the second data communication channel is hereinafter referred to as “a camera data signal DCL”. The request-to-send signal RTS is provided from the camera microcomputer205as a communication master to the lens microcomputer111as a communication slave. The camera data signal DCL includes various control commands and transmission request commands transmitted from the camera microcomputer205to the lens microcomputer111. The lens data signal DLC includes various lens data transmitted from the lens microcomputer111to the camera microcomputer205. The camera and lens microcomputers205and111set their communication speed beforehand and perform the communication (transmission and receipt) at a communication bit rate according to this setting. The communication bit rate indicates a data amount transferable per second and is expressed with a unit of bps (bits per second). The camera and lens microcomputers205and111communicate with each other by a full-duplex communication method enabling mutual transmission and receipt of data.

With reference toFIG. 3, description will be made of communication procedures between the camera and lens microcomputers205and111.FIG. 3illustrates waveforms of communication signals in one frame as a minimum communication unit. The camera data signal DCL and the lens data signal DLC have mutually different parts in their data formats in the one frame.

First, description will be made of the data format of the lens data signal DLC. The lens data signal DLC in the one frame includes, as large parts, a data frame as a first frame and a BUSY frame as a subsequent frame.

The signal level of the lens data signal DLC is held at High in a non-transmission state where data transmission is not performed.

The lens microcomputer111sets the signal level to Low in one bit time period in order to provide a notice of a start of one frame transmission of the lens data signal DLC to the camera microcomputer205. This one bit time period is called “a start bit ST” at which one data frame is started. Next, the lens microcomputer111transmits one-byte lens data in eight bit time period from a subsequent second bit to a ninth bit. The data bits are arranged in an MSB-first format starting from a highest-order data bit D7and continuing to data bits D6, D5, D4, D3, D2and D1in this order and ending with a lowest-order data bit D0.

Then, the lens microcomputer111adds one bit parity information PA at tenth bit and sets the signal level of the lens data signal DLC to High in a time period of a stop bit SP indicating an end of the one frame. Thus, the data frame starting from the start bit ST ends.

Thereafter, the lens microcomputer111adds the BUSY frame after the stop bit SP. The BUSY frame indicates a time period of a communication standby request BUSY as a notice (hereinafter referred to as “a BUSY notice”) from the lens microcomputer111to the camera microcomputer205. The lens microcomputer111holds the signal level of the lens data signal DLC to Low until terminating the communication standby request BUSY.

Description will be made of a method of determination of presence and absence of the BUSY notice; the determination is performed by the camera microcomputer205. The waveform illustrated inFIG. 3includes bit positions B1and B2. The camera microcomputer205selects one of these bit positions B1and B2as a BUSY determination position P for determining the presence and absence of the BUSY notice.

As described above, this embodiment employs a data format that selects the BUSY determination position P from the bit positions B1and B2. This data format enables addressing a problem that a process time from the transmission of the data frame of the lens data signal DLC until the determination of the presence of the BUSY notice (the lens data signal DLC is set to Low) is changed depending on a processing performance of the lens microcomputer111. Whether to select the bit position B1or B2as the BUSY determination position P is set by the communication between the camera and lens microcomputers205and111before the data communication therebetween is performed. The BUSY determination position P is not necessary to be fixed at the bit position B1or B2and may be changed depending on processing capabilities of the camera and lens microcomputers205and111.

Next, description will be made of a data format of the camera data signal DCL. Specifications of the data format of the camera data signal DCL in one frame are common to those of the lens data signal DLC.

However, the addition of the BUSY frame to the camera data signal DCL is prohibited, which is different from the lens data signal DLC.

Next, the communication procedures between the camera and lens microcomputers205and111will be described. The camera microcomputer205sets a signal level of the request-to-send signal RTS to Low (in other words, asserts the request-to-send signal RTS) to provide the transmission request to the lens microcomputer111. The lens microcomputer111having detected the transmission request through the assertion (Low) of the request-to-send signal RTS performs a process to produce the lens dada signal DLC to be transmitted to the camera microcomputer205. Then, after a preparation of the transmission of the lens data signal DLC is completed, the lens microcomputer111starts transmitting one frame of the lens data signal DLC through the first data communication channel.

The lens microcomputer111starts the transmission of the lens data signal DLC within a time period mutually set by the camera and lens microcomputers205and111after the assertion of the request-to-send signal RTS. That is, for the lens microcomputer111, a strict restriction is not provided that it is necessary to set the lens data to be transmitted before a first clock pulse is input thereto in a time period from the assertion of the request-to-send signal RTS to a start of the transmission of the lens data signal DLC.

Next, in response to detecting the start bit ST as a head bit of the data frame of the lens data signal DLC received from the lens microcomputer111(that is, in response to a start of receiving the lens data signal DLC), the camera microcomputer205returns the signal level of the request-to-send signal RTS to High, in other words, negates the request-to-send signal RTS.

The camera microcomputer205thereby terminates the transmission request and starts the transmission of the camera data signal DCL through the second data communication channel. The negation of the request-to-send signal RTS may be performed any one of before and after the start of the transmission of the camera data signal DCL. It is only necessary that these negation and transmission be performed until the receipt of the data frame of the lens data signal DLC is completed.

The lens microcomputer111having transmitted the data frame of the lens data signal DLC adds the BUSY frame to the lens data signal DLC in a case where the BUSY notice is necessary to be provided to the camera microcomputer205. The camera microcomputer205monitors the presence or absence of the BUSY notice and prohibits the assertion of the request-to-send signal RTS for a next transmission request while the BUSY notice is provided. The lens microcomputer111executes necessary processes in a time period where the transmission request from the camera microcomputer205is prohibited by the BUSY notice and terminates the BUSY notice after a next communication preparation is completed. The assertion of the request-to-send signal RTS by the camera microcomputer205for the next transmission request is permitted under a condition that the BUSY notice is terminated and the transmission of the data frame of the camera data signal DCL is completed.

As just described, in this embodiment, in response to the assertion of the request-to-send signal RTS upon a communication starting event generated in the camera microcomputer205, the lens microcomputer111starts transmitting the data frame of the lens data signal DLC to the camera microcomputer205. On the other hand, the camera microcomputer205having detected the start bit ST of the lens data signal DLC starts transmitting the data frame of the camera data signal DCL to the lens microcomputer111. The lens microcomputer111adds, as needed, the BUSY frame to the data frame of the lens data signal DLC for providing the BUSY notice and then terminates the BUSY notice to end one frame communication process. In this communication process, the camera microcomputer205and the lens microcomputer111mutually transmit and receive one byte data.

Next, description will be made of the follow shot assist process performed in the camera system of this embodiment.FIG. 4illustrates communication times between the camera and lens microcomputers205and111and acquisition times of the angular velocity from the gyro sensor129in the follow shot assist process. An accumulation time period401is a charge accumulation time period in the image sensor201for each image-capturing frame. The image sensor201performs charge accumulation in response to a vertical synchronization signal VD as a trigger. The vertical synchronization signal VD is produced at every predetermined image-capturing frame time period ( 1/30 seconds in this embodiment). That is, the time at which the vertical synchronization signal VD is produced is a start time of the charge accumulation in the image sensor201.

This embodiment sets a length of the charge accumulation time period (shutter speed) to 1/50 seconds. Each accumulation time period401(that is, each image-capturing frame) is provided with a frame identifier for identifying that accumulation time period401from other accumulation time periods401.

The camera microcomputer205provides, at every accumulation center time that is a center time of the above-described charge accumulation time period (accumulation time period401) of the image sensor201, an accumulation center notice402to the lens microcomputer111through the transmission of the camera data signal DCL. The accumulation center notice402includes information on a delay time from an accumulation center time point that is a time point corresponding to the accumulation center time set in response to the BUSY notice from the lens microcomputer111. The accumulation center notice402further includes the frame identifier for identifying a current accumulation time period (that is, a current image-capturing frame). The camera microcomputer205can acquire the accumulation center time point from the timer209. The accumulation center time point (predetermined time point) acquired by the camera microcomputer205is hereinafter referred to as “a camera accumulation center time point”.

In the interchangeable lens100, the gyro sensor129detects the angular velocity with a sampling frequency of 4 kHz. The lens microcomputer111stores, at every time of acquiring the angular velocity with this sampling frequency (the time is hereinafter referred to as “an angular velocity sampling time”), the acquired angular velocity with a time point acquired thereat from the timer130to the lens memory128.

The lens microcomputer111having received the accumulation center notice402calculates a lens accumulation center time point by using an RTS time point described later and the delay time included in the accumulation center notice402. Then, the lens microcomputer111calculates an angular velocity at the lens accumulation center time point (the angular velocity is accessory information and hereinafter referred to as “an accumulation center angular velocity”) by a linear interpolation method using the angular velocity and time point stored in the lens memory128. The lens microcomputer111further stores the calculated accumulation center angular velocity and the received frame identifier in relation to each other to the lens memory128. The camera microcomputer205sets, to the camera data signal DCL in the camera communicator208after an elapse of a predetermined time from the transmission of the accumulation center notice402, an angular velocity request403for requesting acquisition (transmission) of the angular velocity and starts communication with the lens microcomputer111to provide thereto the angular velocity request403. The lens microcomputer111having received the angular velocity request403transmits the accumulation center angular velocity and the frame identifier related therewith (this frame identifier is hereinafter referred to as “an angular velocity detection frame identifier”) by the lens data signal DCL to the camera microcomputer205.

The camera microcomputer205acquires (calculates), in every image-capturing frame, a movement amount of the object image (the movement amount is camera information) in the video image produced from the image-capturing signal acquired using the image sensor201, that is, on an image-capturing surface of the image sensor201. The movement amount of the object image calculated in each image-capturing frame corresponds to a movement amount thereof at the accumulation center time in that image-capturing frame.

Then, the camera microcomputer205calculates a follow shot correction amount (as control information) for a current image-capturing frame from the calculated movement amount of the object image on the image-capturing surface and the accumulation center angular velocity acquired from the lens microcomputer111. This calculation (production) of the follow shot correction amount corresponds to a camera process relating to image capturing. When calculating the follow shot correction amount, the camera microcomputer205checks whether or not the frame identifier of the charge accumulation time period in which the movement amount of the object image on the image-capturing surface has been calculated (this frame identifier is hereinafter referred to as “a movement amount calculation frame identifier”) is identical to the angular velocity detection frame identifier received from the lens microcomputer111. If these frame identifiers are identical to each other, the camera microcomputer205calculates the follow shot correction amount for the current image-capturing frame. If these frame identifiers are not identical to each other, the camera microcomputer205uses the follow shot correction amount calculated for a previous image-capturing frame as that for the current image-capturing frame.

The camera microcomputer205transmits, in response to a user's image-capturing instruction from the camera operation unit207, a follow shot correction notice including the calculated follow shot correction amount to the lens microcomputer111. The lens microcomputer111having received the follow shot correction notice drives the image-stabilizing actuator126through the image-stabilizing driver125by a drive amount corresponding to the follow shot correction amount included in the follow shot correction notice.

The lens microcomputer111thus controls the movement of the image-stabilizing lens103to perform the follow shot assist process.

FIG. 5is a flowchart illustrating a process performed by the camera microcomputer205for causing the lens microcomputer111to recognize an accurate accumulation center time point. The camera microcomputer205executes this process and other processes described later according to the above-mentioned camera communication control program.

The camera microcomputer205having acquired the accumulation center time in response to the vertical synchronization signal input from the signal processor203or directly from the signal processor203proceeds to step S501. At step S501, the camera microcomputer205acquires a current time point from the timer209to store it as the camera accumulation center time point that is the time point of acquiring the accumulation center time to the camera memory210.

Next, at step S502, the camera microcomputer205checks whether or not the BUSY notice is provided by the lens data signal DLC. If the BUSY notice is provided, the camera microcomputer205again checks whether or not the BUSY notice is provided. If the BUSY notice is terminated (in other words, after receipt of the lens data signal DLC is completed), the camera microcomputer205proceeds to step S503.

At step S503, the camera microcomputer205acquires a current time point from the timer209and calculates a difference (delay time) between the current time point at which the BUSY notice is terminated and the camera accumulation center time point stored at step S501in the camera memory210. Then, the camera microcomputer205sets the calculated delay time and the frame identifier for identifying a current image-capturing frame to the camera data signal DCL.

Thereafter, at step S504, the camera microcomputer205asserts the request-to-send signal RTS to cause the lens microcomputer111to start communication with the camera microcomputer205. At step S505, the camera microcomputer205waits for the start bit ST of the lens data signal DLC transmitted from the lens microcomputer111. The lens data signal DLC transmitted here from the lens microcomputer111corresponds to mere response data including no significant information.

At step S506, the camera microcomputer205having detected the start bit ST of the lens data signal DLC transmits the camera data signal DCL set at step S503to the lens microcomputer111. That is, the camera microcomputer205transmits, by the camera data signal DCL, the accumulation center notice (the delay time from the camera accumulation center time point and the frame identifier) as a specific command to the lens microcomputer111. The camera microcomputer205detects the start bit ST of the lens data signal DLC and starts the transmission of the accumulation center notice without delay from the termination of the BUSY notice by the lens microcomputer111and the assertion of the request-to-send signal RTS by the camera microcomputer205. Therefore, the above-described delay time can be regarded as a delay time from the camera accumulation center time point until a time point at which the transmission and receipt of the accumulation center notice are started in response to the assertion of the request-to-send signal RTS.

Then, at step S507, the camera microcomputer205receives the lens data signal DLC from the lens microcomputer111. In this embodiment, the lens data signal DLC received here by the camera microcomputer205includes no significant information.

Next, with reference to a flowchart ofFIG. 6, description will be made of a process performed by the camera microcomputer205for acquiring the angular velocity from the lens microcomputer111. The camera microcomputer205having acquired the movement amount of the object image (hereinafter referred to as “an object movement amount in a current image-capturing frame”) on the image-capturing surface from the video signal produced using the image sensor201proceeds to step S901.

At step S901, the camera microcomputer205sets the angular velocity request to the camera data signal DCL in the camera communicator208to start communication for transmitting the angular velocity request to the lens microcomputer111. At step S902, the camera microcomputer205receives the accumulation center angular velocity by the lens data signal DLC from the lens microcomputer111. The lens data signal DLC received here includes the angular velocity detection frame identifier related to the accumulation center angular velocity.

Next, at step S903, the camera microcomputer205checks whether or not the movement amount calculation frame identifier related to the object movement amount in the current image-capturing frame is identical to the angular velocity detection frame identifier received from the lens microcomputer111at step S902. If these frame identifier are identical to each other, the camera microcomputer205proceeds to step S904. If these frame identifier are not identical to each other, the camera microcomputer205proceeds to step S905.

At step S904, the camera microcomputer205calculates, from the object movement amount in the current image-capturing frame and the accumulation center angular velocity received at step S902, the follow shot correction amount for the current image-capturing frame. Then, the camera microcomputer205stores the calculated follow shot correction amount with the accumulation center time point to the camera memory210.

On the other hand, at step S905, the camera microcomputer205reads out, from the camera memory210, the follow shot correction amount calculated and stored for a one previous image-capturing frame. Then, the camera microcomputer205stores this one previous follow shot correction amount as the follow shot correction amount for the current image-capturing frame with the accumulation center time point in the current image-capturing frame to the camera memory210.

Next, at step S906, the camera microcomputer205determines whether or not the user's image capturing instruction is input from the camera operation unit207.

If the user's image capturing instruction is input, the camera microcomputer205proceeds to step S907to transmit the follow shot correction notice including the follow shot correction amount stored in the camera memory210at step S904or S905to the lens microcomputer111by the camera data signal DCL. Then, the camera microcomputer205ends this process.

Next, with reference to a flowchart ofFIG. 7, description will be made of a process performed by the lens microcomputer111. The lens microcomputer111executes this process and other processes described later according to the above-mentioned lens communication control program.

In response to detecting at step S601the assertion of the request-to-send signal RTS by the camera microcomputer205at step S504inFIG. 5, the lens microcomputer111proceeds to step S602. At step S602, the lens microcomputer111acquires a current time point from the timer130to store it, to the lens memory128, as an RTS time point (first time point) at which the request-to-send signal RTS is asserted.

Next, at step S603, the lens microcomputer111checks whether or not there is any process to be prioritized than the follow shot assist process. Such processes to be prioritized include the zoom process and the AF process. If there is such a process to be prioritized, the lens microcomputer111returns to step S603. If there is no process to be prioritized, the lens microcomputer111proceeds to step S604.

At step S604, the lens microcomputer111transmits the lens data signal DLC to the camera microcomputer205. The lens data signal DLC transmitted here is the response data received by the camera microcomputer205at step S505inFIG. 5and includes no significant information.

Next, at step S605, the lens microcomputer111receives the camera data signal DCL from the camera microcomputer205. Then, at step S606, the lens microcomputer111interprets a command included in the received camera data signal DCL. Such commands included in the received camera data signal DCL include the focus drive command and the accumulation center notice; each command is constituted by a command and its arguments. The argument of the accumulation center notice is constituted by the delay time from the camera accumulation center time point and the frame identifier.

Next, at step S607, the lens microcomputer111determines whether or not the received command is the accumulation center notice as the specific command. If the received command is the accumulation center notice, the lens microcomputer111proceeds to step S608. If the received command is not the accumulation center notice, the lens microcomputer111ends this process.

At step S608, the lens microcomputer111subtracts the delay time received at step S606from the RTS time point stored in the lens memory128to acquire the lens accumulation center time point (second time point). The delay time subtracted from the RTS time point can be regarded, as described above, as the delay time from the camera accumulation center time point to the time point at which the receipt of the accumulation center notice is started by the lens microcomputer111. The time point at which the receipt of the accumulation center notice is started corresponds to the RTS time point. Thus, the lens accumulation center time point calculated using these RTS time point and the delay time corresponds to the camera accumulation center time point.

Next, at step S609, the lens microcomputer111calculates the accumulation center angular velocity by the linear interpolation method using multiple combinations of the angular velocity stored in the lens memory128at each angular velocity sampling time and the time point of acquiring that angular velocity. The lens microcomputer111further stores, to the lens memory128, the calculated accumulation center angular velocity and the frame identifier received at step S606(this frame identifier becomes the angular velocity detection frame identifier) in relation to each other. Then, the lens microcomputer111ends this process.

Next, with reference to a flowchart ofFIG. 8, description will be made of a process performed by the lens microcomputer111for transmitting the accumulation center angular velocity to the camera microcomputer205. In response to receiving the angular velocity request at step S1001by the camera data signal DCL from the camera microcomputer205, the lens microcomputer111proceeds to step S1002.

At step S1002, the lens microcomputer111reads out the accumulation center angular velocity and the angular velocity detection frame identifier related therewith from the lens memory128, and deletes these read-out accumulation center angular velocity and angular velocity detection frame identifier from the lens memory128.

Next, at step S1003, the lens microcomputer111transmits the accumulation center angular velocity and the angular velocity detection frame identifier read out at step S1002to the camera microcomputer205by the lens data signal DLC.

In this embodiment, the camera microcomputer205transmits the delay time from the camera accumulation center time point set in response to the BUSY frame added to the lens data signal DLC to the lens microcomputer111by the camera data signal DCL. The lens microcomputer111subtracts the camera accumulation center time point from the RTS time point and thereby can acquire the lens accumulation center time point corresponding to an accurate accumulation center time point in the camera body200. This process enables the lens microcomputer111to acquire the accurate accumulation center time point in the camera body200even though the BUSY frame is added to the lens data signal DLC or the transmission of the lens data signal DLC is delayed.

As a result, the interchangeable lens100can acquire the angular velocity (accumulation center angular velocity) at the time point of acquiring the object movement amount on the image-capturing surface in the camera body200. That is, an accurate synchronization can be achieved between the time of acquiring the object movement amount on the image-capturing surface in the camera body200and the time of acquiring the angular velocity in the interchangeable lens100. Accordingly, a decrease in accuracy of the follow shot assist process due to a difference between the time point of acquiring the object movement amount on the image-capturing surface and the time point of acquiring the angular velocity can be avoided. In other words, a highly accurate (good) follow shot assist process can be performed.

Next, description will be made of a second embodiment (Embodiment 2) of the present invention. Embodiment 1 described the case where the camera microcomputer205cannot request the lens microcomputer111to perform communication (that is, cannot assert the request-to-send signal RTS) while the lens microcomputer111is transmitting the BUSY notice. On the other hand, this embodiment will describe a case where the camera microcomputer205can assert the request-to-send signal RTS while the lens microcomputer111is transmitting the BUSY notice.

Configurations of an interchangeable lens100and a camera body200are the same as those in Embodiment 1, and constituent elements common to those in Embodiment 1 are denoted by the same reference numerals as those in Embodiment 1.

With reference to a flowchart ofFIG. 9, description will be made of a process performed by the camera microcomputer205in this embodiment. The camera microcomputer205having acquired the accumulation center time in response to the vertical synchronization signal input from the signal processor203or directly from the signal processor203proceeds to step S701. At step S701, regardless of whether or not the lens microcomputer111is transmitting the BUSY notice, the camera microcomputer205asserts the request-to-send signal RTS to cause the lens microcomputer111to start communication.

Then, in response to detecting the start bit ST of the lens data signal DLC transmitted from the lens microcomputer111at step S703, the camera microcomputer205transmits the accumulation center notice as the specific command to the lens microcomputer111by the camera data signal DCL. In this embodiment, the camera microcomputer205having acquired the accumulation center time immediately asserts the request-to-send signal RTS, and the lens microcomputer111transmits the lens data signal DLC to the camera microcomputer205in response to the assertion of the request-to-send signal RTS. The camera microcomputer205further transmits the accumulation center notice to the lens microcomputer111in response to detecting the start bit ST of the received lens data signal DLC. The accumulation center notice is transmitted without delay from the assertion of the request-to-send signal RTS (that is, from the acquisition of the accumulation center time). Therefore, the accumulation center notice can be regarded as being performed at the same time point as the camera accumulation center time point.

Step S704is identical to step S507inFIG. 5described in Embodiment 1.

Next, with reference to a flowchart ofFIG. 10, description will be made of a process performed by the lens microcomputer111in this embodiment. In response to detecting at step S801the assertion of the request-to-send signal RTS by the camera microcomputer205at step S701inFIG. 9, the lens microcomputer111proceeds to step S802.

At step S802, the lens microcomputer111acquires a current time point from the timer130to store it, to the lens memory128, as an RTS time point (first time point) at which the request-to-send signal RTS is asserted. In this embodiment, as described above, the camera microcomputer205having acquired the accumulation center time immediately asserts the request-to-send signal RTS (step S701inFIG. 9). Therefore, the RTS time point at which the lens microcomputer111detects the assertion corresponds to the lens accumulation center time point corresponding to the time point (camera accumulation center time point) at which the camera microcomputer205acquires the accumulation center time.

When the command received at step S807from the camera microcomputer205is the accumulation center notice as the specific command, the lens microcomputer111proceeds to step S808. At step S808, the lens microcomputer111calculates the angular velocity at the RTS time point, that is, the accumulation center angular velocity by the linear interpolation method using multiple combinations of the angular velocity stored in the lens memory128at each angular velocity sampling time and the time point of acquiring that angular velocity. The lens microcomputer111further stores, to the lens memory128, the calculated angular velocity at the RTS time point and the frame identifier received at step S806(this frame identifier becomes the angular velocity detection frame identifier) in relation to each other. Then, the lens microcomputer111ends this process.

Also in this embodiment, the camera microcomputer205performs the same process as that described in Embodiment 1 with reference toFIG. 6, and the lens microcomputer111performs the same process as that described in Embodiment 1 with reference toFIG. 8. Thus, the follow shot assist process is performed.

As described above, in this embodiment the camera microcomputer205having acquired the accumulation center time immediately asserts the request-to-send signal RTS even though the BUSY notice is being transmitted from the lens microcomputer111. Therefore, the lens microcomputer111acquires the RTS time point at which the request-to-send signal RTS is asserted by the camera microcomputer205as the lens accumulation center time point. This process enables the lens microcomputer111to acquire the accurate accumulation center time point in the camera body200even though the BUSY frame is added to the lens data signal DLC or the transmission of the lens data signal DLC is delayed.

As a result, an accurate synchronization can be achieved between the time of acquiring the object movement amount on the image-capturing surface in the camera body200and the time of acquiring the angular velocity in the interchangeable lens100, and thereby a highly accurate (good) follow shot assist process can be performed.

Each of the above embodiments described the case where the lens microcomputer111acquires the angular velocity as the accessory information changing with time. However, the accessory information may be other information such as a position of the magnification-varying lens102, the focus lens104or the image-stabilizing lens103as long as information changing with time. Furthermore, although each of the above embodiments described the case of performing the follow shot assist process, the communication described in each of the above embodiments can be used in a case of performing other process than the follow shot assist process, such as a control process or a calculation process.

Each of the above embodiments enables, in the lens-interchangeable camera system, performing a process such as a control process or a calculation process using data whose acquisition times are accurately synchronized with each other.

With reference toFIG. 11, description will be made of a lens-interchangeable camera system10as an image-capturing system (or an image-capturing apparatus) of a third embodiment (Embodiment 3) of the present invention.FIG. 11illustrates a configuration of the camera system10of this embodiment. The camera system10includes a camera body1100as an image-capturing apparatus and an interchangeable lens1200as a lens apparatus (or an accessory apparatus) detachably attachable to the camera body1100.

As illustrated inFIG. 11, the interchangeable lens1200is detachably attached to the camera body1100via a lens mount12. The interchangeable lens1200is provided with an image-capturing optical system including a focus lens1201, a zoom (magnification-varying) lens1202, a stop unit (aperture)1203and an image-stabilizing lens1204. AlthoughFIG. 11illustrates each of the focus lens1201, the zoom lens1202and the image-stabilizing lens1204as a single lens, each thereof may be constituted by multiple lenses. A light flux from an object (not illustrated) entering the image-capturing optical system reaches an image sensor1102to form an object image (optical image) on the image sensor1102.

First, description will be made of a configuration of the camera body1100. In the camera body1100, a shutter1101controls an exposure amount of the image sensor1102. The image sensor1102is constituted by a CCD sensor or a CMOS sensor and photoelectrically converts the object image into an analog image-capturing signal. The image sensor1102may include multiple pixels (focus detection pixels) used for focus detection. An A/D converter1103converts the analog image-capturing signal output from the image sensor1102into a digital image-capturing signal to output the digital image-capturing signal to an image processor1140and a memory controller1105. An optical viewfinder1114and mirrors1112and1113enable a user to observe the object image when the mirror1112is located in an image capturing optical path from the image-capturing optical system (that is, located at a down position) as illustrated inFIG. 11. A timing generator1104supplies clock signals and synchronization signals to the image sensor1102, the A/D converter1103, the image processor1140, the memory controller1105and a system controller1130described later.

The image processor1140performs predetermined image processes such as a pixel interpolation process and a color conversion process on the digital image-capturing signal from the A/D converter1103or on data from the memory controller1105to produce image data. The image processor1140performs a predetermined calculation process using the produced image data. The image processor1140determines a position of the object (object image) in the image data and follows the object by using its color and shape. The image processor1140further includes a motion vector detector1141. The motion vector detector1141detects, in a first time period, a motion vector (motion vector amount) by using the positions of the object over multiple frames in the image data (video data). The position of the object includes upper left coordinates of the object, a height and a width thereof. The result of the calculation performed by the image processor1140is output to the system controller1130via the memory controller1105.

The memory controller1105controls the A/D converter1103, the timing generator1104, the image processor1140, a memory1107, a recorder1108and an image display unit1106. The image data output from the image processor1140is written, through the memory controller1105, to the memory1107and the recorder1108. The memory1107and the recorder1108each store the image data as the video data or a still image data. The memory1107is constituted by a volatile memory and used as a work area for the system controller1130. The recorder1108is constituted by a non-volatile memory provided inside or detachably attached to the camera body1100and is used as an image recording area.

The image display unit1106is constituted by an LCD or the like and is used as an electronic viewfinder (EFV) that displays a video image or a still image corresponding to the image data produced by the image processor1140or recorded in the recorder1108. A shutter controller1110controls, with a mirror controller1111, the shutter1101in response to a control signal from the system controller1130. The mirror controller1111controls down (insertion) and up (retraction) operations of the mirror1112with respect to an image-capturing optical path in response to the control signal from the system controller1130.

The system controller1130controls the entire camera system10including the camera body1100and the interchangeable lens1200in response to input signals from a first shutter switch (SW1)1115, a second shutter switch (SW2)1116, a camera operation unit1117and the memory controller1105. That is, the system controller1130controls, in response to the input signals, the image sensor1102, the memory controller1105, the shutter controller1110and the mirror controller1111in the camera body1100and further controls the interchangeable lens1200via a camera I/F1120.

The first shutter switch (SW1)1115operated by the user instructs, to the system controller1130, a start of operations such as an AF process, an AE process and an AWB process. The second shutter switch (SW2)1116operated by the user instructs a start of an exposure operation to the system controller1130. The system controller1130having received the exposure start instruction controls the mirror controller1111, the shutter controller1110and the memory controller1105and controls the interchangeable lens1200via the camera I/F1120to start the exposure operation, that is, an image-capturing operation of the image sensor1102and an image recording operation of the recorder1108. The system controller1130ends the image-capturing operation of the image sensor1102in response to an elapse of a predetermined exposure time.

Then, the system controller1130causes the A/D converter1103to convert the analog image-capturing signal output from the image sensor1102into the digital image-capturing signal, causes the image processor1140to produce the image data as a still image data and causes the memory controller1105to store the still image data. The memory controller1105stores the still image data with an image capturing condition for capturing the still image data and a result of a follow shot assist process (hereinafter referred to as “follow shot assisted result”) when the follow shot assist process is performed. Thereafter, the system controller1130causes the memory controller1105to store the still image data to the recorder1108as compressed image data or RAW image data. The image-capturing condition and the follow shot assisted result are recorded as EXIF information in the still image data.

The camera operation unit1117includes operation members such as a power-on/off button, other buttons and a touch panel and outputs instructions corresponding to user's operations for the respective operation members to the system controller1130. The system controller1130performs, in response to the instructions from the camera operation unit1117, switching of operation modes provided in the camera body1100such as an AF mode, an AE mode and a follow shot assist mode. The camera power controller1118manages an external battery and a built-in battery provided to the camera body1100. The camera power controller1118performs, when the battery is removed or a remaining battery level becomes zero, a forced shut-down process of the operations of the camera body1100. The system controller1130shuts down power supply to the interchangeable lens1200in response to the forced shut-down process.

An AF controller1131included in the system controller1130controls the AF process. In the AF process, the AF controller1131calculates, according to a user-selected AF mode, a drive amount of the focus lens1201depending on lens information acquired from the interchangeable lens1200via the camera I/F1120, such as a position of the focus lens1201and a focal length of the image-capturing optical system, and on an AF evaluation value described later. The AF controller1131transmits the drive amount of the focus lens1201to the interchangeable lens1200via a communication controller1133included in the system controller1130and the camera I/F1120. When the AF mode is a phase difference AF mode or an imaging-surface phase difference AF mode, the AF controller1131calculates, as the AF evaluation value, a phase difference of paired object images formed on a focus detection sensor via the mirror1112and a sub mirror (not illustrated) or on the focus detection pixels of the image sensor1102and calculates the drive amount of the focus lens1201from the phase difference. On the other hand, when the AF mode is a contrast AF mode, the AF controller1131calculates the drive amount of the focus lens1201by using, as the AF evaluation value, a contrast evaluation value calculated from the digital image-capturing signal or the video data by the image processor1140. The AF controller1131switches, in response to a user-selected one of AF evaluation modes such a single-point AF mode, a multipoint AF mode and a face detection AF mode, a position of an AF frame where the AF evaluation value is calculated in an image-capturing area.

The AE controller1132included in the system controller1130controls the AE process. In the AE process, the AE controller1132calculates, according to a user-selected image-capturing mode (AE mode), an AE control amount (including a stop control amount, a shutter speed and an exposure sensitivity) by using the lens information such as a full-open F-number and the focal length acquired from the interchangeable lens1200via the camera I/F1120and an AE evaluation value.

The AE controller1132transmits the stop control amount to the interchangeable lens1200via the communication controller1133and the camera I/F1120.

The AE controller1132inputs the shutter speed to the shutter controller1110and inputs the exposure sensitivity to the image sensor1102. When the image-capturing mode is a viewfinder image-capturing mode, the AE controller1132calculates the AE control amount depending on an AE evaluation value acquired from a luminance detector (not illustrated) that detects a luminance of the object image formed thereon via the mirrors1112and1113. On the other hand, when the image-capturing mode is a live-view image-capturing mode, the AE controller1132calculates the AE control amount depending on an AE evaluation value calculated by the image processor1140. The AE controller1132further switches, according to a user-selected one of photometry modes such as an evaluation photometry mode, an averaging photometry mode and a face detection photometry mode, a position of an AE frame where the AE evaluation value is calculated and a weighting amount applied thereon.

A follow shot assist controller (calculator)1134included in the system controller1130controls the follow shot assist process. The follow shot assist process is performed in the live-view image-capturing mode and can be performed only when the interchangeable lens1200is compatible with the follow shot assist process. When the interchangeable lens1200is not compatible with the follow shot assist process, the follow shot assist controller1134controls only an image flow amount in the follow shot assist mode. Specifically, the follow shot assist controller1134calculates, from an angular velocity (hereinafter referred to as “a lens angular velocity”) detected by an angular velocity detector1208included in the interchangeable lens1200, a shutter speed for limiting an image blur amount during the exposure to a predetermined amount and provides the shutter speed to the AE controller1132, thereby controlling the image flow amount. When the camera body1100includes an angular velocity detector, the angular velocity can be acquired by using this angular velocity detector.

On the other hand, when the interchangeable lens1200is compatible with the follow shot assist process, in the follow shot assist mode the follow shot assist controller1134requests the interchangeable lens1200to perform an operation for the follow shot assist process via the camera I/F1120. The follow shot assist controller1134further calculates, using the lens angular velocity and the lens information such as the focal length acquired from the interchangeable lens1200via the camera I/F1120and the motion vector amount input from the motion vector detector1141in the image processor140, an angular velocity of an object (hereinafter referred to as “object angular velocity”). In this embodiment, the object angular velocity includes not only the angular velocity, but also an angular acceleration rate of the object.

Furthermore, the follow shot assist controller1134calculates, using a frame rate and the shutter speed, a setting value of a lens angular velocity detection time period such that the lens angular velocity detection time period is identical (corresponds) to a motion vector detection time period as the above-mentioned first time period. The object angular velocity and the setting value of the lens angular velocity detection time period are transmitted to the interchangeable lens1200via the communication controller1133and the camera I/F1120. The setting value of the lens angular velocity detection time period is provided with an ID. This ID (hereinafter referred to as “a first detection time period ID”) as a first ID information is added to the lens angular velocity detection time period so as to enable the follow shot assist controller1134to determine which lens angular velocity detection time period the lens angular velocity to be acquired from the interchangeable lens1200is detected in. Therefore, the lens angular velocity is also provided with an ID (hereinafter referred to as “a second detection time period ID”) as second ID information. The lens angular velocity is transmitted from the interchangeable lens1200to the camera body1100in relation with the second detection time period ID.

The follow shot assist controller1134allocates, to the motion vector detection time period as the first time period, a detection time period ID (hereinafter referred to as “a motion vector detection time period ID”) identical to the first detection time period ID. The follow shot assist controller1134stores the motion vector (amount) detected in that motion vector detection time period and the allocated motion vector detection time period ID″ in relation to each other to an internal memory (not illustrated) in the system controller1130or the memory1107. As described above, the follow shot assist controller1134adds the first detection time period ID to the lens angular velocity detection time period set so at to be identical to the motion vector detection time period and adds the motion vector detection time period ID identical to the first detection time period ID to the motion vector detection time period. Then, the follow shot assist controller1134transmits the object angular velocity, the setting value of the lens angular velocity detection time period and the first detection time period ID to the interchangeable lens1200.

The lens controller1210in the interchangeable lens1200stores the first detection time period ID received from the camera body1100in relation with the lens angular velocity detected in the lens angular velocity detection time period received from the camera body1100as angular velocity information to an internal memory (not illustrated) in the lens controller1210or a memory1212. The lens controller1210transmits, in response to a request from the camera body1100, the lens angular velocity with the second detection time period ID to the camera body1100.

The follow shot assist controller1134in the camera body1100compares the motion vector detection time period ID (that is, the detection time period ID) related to the motion vector with the second detection time period ID related to the lens angular velocity received from the interchangeable lens1200. The follow shot assist controller1134determines, depending on whether or not the first and second detection time periods ID are identical to each other, whether or not the communication with the interchangeable lens1200has been performed at an expected time.

The communication controller1133in the system controller1130in the camera body1100controls a communication process between the camera body1100and the interchangeable lens1200. In response to detecting that the interchangeable lens1200is attached to the camera body1100through the camera I/F1120, the communication controller1133starts the communication between the camera body1100and the interchangeable lens1200to receive the lens information and transmit the camera information and various drive commands. For example, when the image-capturing mode is set to the live-view image-capturing mode and the interchangeable lens1200is compatible with the follow shot assist process, the communication controller1133performs, in response to an input of an image-capturing synchronization signal from the timing generator, a synchronization signal communication for notifying of a communication start delay time from the input of the image-capturing synchronization signal until the communication is started. When the exposure started in response to the user's operation of the second shutter switch (SW2)1116, the communication controller1133receives information on the follow shot assisted result from the interchangeable lens1200. In the live-view image-capturing mode, in response to an input of the image-capturing synchronization signal from the timing generator1104, the communication controller1133collectively receives the lens information including the position of the focus lens1201, a stop state (F-number) of the stop unit1203, the focal length and others.

The camera I/F1120is an interface for the communication between the camera body1100and the interchangeable lens1200. The camera I/F1120enables the system controller1130in the camera body1100to communicate with the lens controller1210in the interchangeable lens1200by using electric signals via a connector20and the communication controller1133, thereby enabling transmitting and receiving the control commands and lens information between the system controller1130and the lens controller1210.

Next, description will be made of a configuration of the interchangeable lens1200. The focus lens1201is moved in an optical axis direction along an optical axis OA to change a focus state of the image-capturing optical system. A focus controller1205is controlled by the lens controller1210to drive the focus lens1201. The focus controller1205outputs focus information such as the position of the focus lens1201to the lens controller1210.

A zoom lens1202is moved in the optical axis direction to change the focal length of the image-capturing optical system. A zoom controller1206is controlled by the lens controller1201to drive the zoom lens1202. The zoom controller1206outputs zoom information such as the focal length to the lens controller1210. The stop unit1203has a variable aperture diameter (F-number) that changes an amount of light passing therethrough. A stop controller1207is controlled by the lens controller1210to drive the stop unit1203. The stop controller1207outputs stop information such as the F-number to the lens controller1210.

An image-stabilizing lens1204is moved in a direction orthogonal to the optical axis OA to reduce image blur caused by camera shaking due to user's hand jiggling or the like. An image-stabilization controller1209is controlled by the lens controller1210to drive the image-stabilizing lens1204. The image-stabilization controller1209outputs image-stabilization information such as an image-stabilization range to the lens controller1210.

The angular velocity detector1208detects lens angular velocities of the interchangeable lens1200in a yaw direction and a pitch direction to output the detected lens angular velocities to the lens controller1210. The angular velocity detector1208is controlled by the lens controller1210. The angular velocity detector may be provided to the camera body1100.

A lens operation unit1211includes a focus operation ring, a zoom operation ring, an AF/MF switch and an IS (image-stabilization)-on/off switch and outputs instructions depending on user's operations thereof to the lens controller1210. The lens controller1210switches, in response to the user's operations of the lens operation unit1211, operation modes of various functions provided in the interchangeable lens1200. The memory1212is constituted by a volatile memory.

The lens controller1210controls, in response to input signals from the lens operation unit1211and a lens I/F1220, the focus controller1205, the zoom controller1206, the stop controller1207, the image-stabilization controller1209and the angular velocity detector1208. Thus, the lens controller1210controls the entire interchangeable lens1200. In addition, the lens controller1210transmits, in response to receiving lens information requests from the camera body1100via the lens I/F1220, the lens information input from the other controllers1205to1207and1209and the lens angular velocity detected by the angular velocity detector1208to the camera body1100via the lens I/F1220.

The lens I/F1220is an interface for the communication between the interchangeable lens1200and the camera body1100. The lens I/F1220enables the lens controller1210in the interchangeable lens1200to communicate with the system controller1130in the camera body1100by using electric signals via the connector20, thereby enabling transmitting and receiving the lens information and the control commands between the lens controller1210and the system controller1130.

Next, with reference to a flowchart ofFIG. 12, description will be made of an image-capturing synchronization communication process performed by the system controller1130in the camera body1100. FIG. illustrates the image-capturing synchronization communication process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. The system controller1130executes this process and other processes described later according to a camera communication control program as a computer program. The image-capturing synchronization communication process is performed in the live-view image-capturing mode (that is, a live-view image capturing is being performed) and is a process for causing the system controller1130to perform an image-capturing synchronization communication with the interchangeable lens1200at a time at which the image-capturing synchronization signal is input.

First, at step S1201, the system controller1130determines whether or not the live-view image capturing is currently being performed. If the live-view image capturing is being performed, the system controller1130proceeds to step S1202. If the live-view image capturing is not being performed, the system controller1130ends this image-capturing synchronization communication process.

At step S1202, the system controller1130determines whether or not the image-capturing synchronization signal is input.

If the image-capturing synchronization signal is input, the system controller1130proceeds to step S1203. If the image-capturing synchronization signal is not input, the system controller1130returns to step S1201.

At step S1203, the system controller1130stores a time point at which the image-capturing synchronization signal is input as an image-capturing synchronization signal time point to the internal memory (not illustrated) in the system controller1130or the memory1107.

Next, at step S1204, the system controller1130determines whether or not an unfinished lens communication remains. If the unfinished lens communication remains, the system controller1130proceeds to step S1205. If the unfinished lens communication does not remain, the system controller1130proceeds to step S1206.

At step S1205, the system controller1130performs the unfinished lens communication and then proceeds to step S1206.

At step S1206, the system controller1130determines whether or not to perform the synchronization signal communication. When the interchangeable lens1200is compatible with the follow shot assist process and the follow shot assist mode is set, the system controller1130determines to perform the synchronization signal communication and proceeds to step S1207. On the other hand, when determining not to perform the synchronization signal communication, the system controller1130returns to step S1201.

At step S1207, the system controller1130measures an elapsed time from the image-capturing synchronization signal time point and stores this elapsed time as a delay time (hereinafter referred to as “a synchronization signal communication delay time”) to the internal memory or the memory1107.

Next, at step S1208, the system controller1130performs the synchronization signal communication to the interchangeable lens1200via the camera I/F1120. The synchronization signal communication transmits data (transmission data) including the synchronization signal communication delay time.

Next, at step S1209, the system controller1130performs a setting value communication for transmitting the lens angular velocity detection time period (lens angular velocity detection time period receiving process) to the interchangeable lens1200via the camera I/F1120and then returns to step S1201. The system controller1130transmits, as transmission data of the setting value communication, the above-described setting value of the lens angular velocity detection time period input from the follow shot assist controller1134. As described above, the setting value of the lens angular velocity detection time period includes the first detection time period ID output from the follow shot assist controller1134.

The image-capturing synchronization communication process described above enables the camera body1100to notify the interchangeable lens1200of the image-capturing synchronization signal and enables the camera body1100to set the lens angular velocity detection time period.

Next, with reference to a flowchart ofFIG. 13, description will be made of an exposure setting process performed by the system controller1130and the follow shot assist controller1134in the camera body1100.FIG. 13illustrates the exposure setting process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. The exposure setting process is performed for every frame in the live-view image-image capturing mode in order to perform an exposure control for a next frame.

First, at step S1301, the system controller1130determines whether or not the live-view image capturing is being performed. If the live-view image capturing is being performed, the system controller1130proceeds to step S1302. If the live-view image capturing is not being performed, the system controller1130ends this exposure setting process.

At step S1302, the system controller1130determines whether or not an exposure setting time of the image sensor1102for the next frame has come. If the exposure setting time has come, the system controller1130proceeds to step S1303. If the exposure setting time has not yet come, the system controller1130returns to step S1301.

At step S1303, the system controller1130calculates an exposure setting value depending on the AE control amount and the set image-capturing mode. The system controller1130further outputs the exposure setting value to the memory controller1105to perform the exposure control for the next frame.

Next, at step S1304, the system controller1130causes the follow shot assist controller1134to determine whether or not to perform the follow shot assist process. When the interchangeable lens1200is compatible with the follow shot assist process and the follow shot assist mode is set, the follow shot assist controller1134determines to perform the follow shot assist process and then proceeds to step S1305. On the other hand, when determining not to perform the follow shot assist process, the system controller1130returns to step S1301.

At step S1305, the follow shot assist controller1134calculates, depending on the exposure setting value for the next frame and others, the setting value of the lens angular velocity detection time period such that the lens angular velocity detection time period is identical (corresponds) to the motion vector detection time period, as a relative time from the image-capturing synchronization signal time point. The calculated setting value of the lens angular velocity detection time period is transmitted at step S1209described above to the interchangeable lens1200. The setting value of the lens angular velocity detection time period includes the first detection time period ID.

As described above, the first detection time period ID is added to the lens angular velocity detection time period so as to enable the follow shot assist controller1134to determine which lens angular velocity detection time period the lens angular velocity acquired from the interchangeable lens1200is detected in. Therefore, the lens angular velocity is also provided with the second detection time period ID and is transmitted to the camera body1100in relation with the second detection time period ID.

Next, as step S1306, the follow shot assist controller1134determines whether or not the motion vector detection time period ID (that is, the first detection time period ID) corresponding to the motion vector to be used is identical to the second detection time period ID corresponding to the lens angular velocity received from the interchangeable lens1200. If these IDs are identical to each other, the follow shot assist controller1134proceeds to step S1307. If these IDs are not identical to each other, the follow shot assist controller1134proceeds to step S1308.

At step S1307, the follow shot assist controller1134calculates the object angular velocity using the lens angular velocity and the lens information such as the focal length received from the interchangeable lens1200and on the motion vector amount input from the image processor1140(motion vector detector1141). As described above, the object angular velocity includes not only the angular velocity but also the angular acceleration rate. The follow shot assist controller1134further inputs the calculated object angular velocity to the communication controller1133. The object angular velocity is provided with an angular velocity acquisition time point corresponding to the lens angular velocity used for calculating the object angular velocity.

At step S1308, the communication controller1133performs an object angular velocity communication in order to transmit the object angular velocity with the first detection time period ID to the interchangeable lens1200and then returns to step S1301.

The above-described exposure setting process enables the camera body1100to perform the exposure control for the next frame and to set the lens angular velocity detection time period to be notified to the interchangeable lens1200in response to a next image-capturing synchronization signal. Furthermore, the exposure setting process enables the camera body1100to transmit the object angular velocity to the interchangeable lens1200and to receive the lens angular velocity from the interchangeable lens1200.

Next, with reference to a flowchart ofFIG. 14, description will be made of an exposure process performed by the system controller1130and the follow shot assist controller1134in the camera body1100.FIG. 14illustrates a live-view exposure process when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. The live-view exposure process is started in response to the exposure start instruction (image-capturing start instruction) from the second shutter switch (SW2)1116in the live-view image-image capturing mode.

First, at step S1401, the system controller1130notifies the interchangeable lens1200that it is an exposure start time (image-capturing start time) through communication therewith via the communication controller1133.

Next, at step S1402, the system controller1130controls the shutter controller1110and the image sensor1102so as to perform the exposure process to acquire image data. The acquired image date is stored to the memory1107through the image processor1140and the memory controller1105.

Next, at step S1403, the system controller1130causes the follow shot assist controller1134to determine whether or not to perform the follow shot assist process. When the interchangeable lens1200is compatible with the follow shot assist process and the follow shot assist mode is set, the follow shot assist controller1134determines to perform the follow shot assist process and then proceeds to step S1404. On the other hand, when determining not to perform the follow shot assist process, the system controller1130proceeds to step S1405.

At step S1404, the follow shot assist controller1134performs communication for receiving the follow shot assisted result from the interchangeable lens1200via the communication controller1133. The follow shot assist controller1134thereby acquires, as the follow shot assisted result, an image-stabilized result in the exposure process performed using the object angular velocity. Then, the follow shot assist controller1134proceeds to step S1405.

At step S1405, the system controller1130produces EXIF information to be included in an image file. The EXIF information is stored to the memory1107via the memory controller105. In this embodiment, the EXIF information includes, in addition to the image-capturing condition including the image-capturing mode, the focal length, the shutter speed and the F-number, the follow shot assisted result received at step S1404.

Next, at step S1406, the system controller1130controls the image processor1140to cause it to produce the image file from the image data and the EXIF information. The system controller1130further stores the image file to the memory1107via the memory controller1105and then records the image file to the recorder1108.

The above-described exposure process enables the camera body1100to acquire the result of the follow shot assist process performed in the exposure process from the interchangeable lens1200and to add that follow shot assisted result to the image data or to display the follow shot assisted result on the image display unit1106.

Next, with reference to a flowchart ofFIG. 15, description will be made of a synchronization signal communication receiving process performed by the lens controller1210in the interchangeable lens1200for receiving the synchronization signal communication from the camera body1100.FIG. 15illustrates the synchronization signal communication receiving process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. This process is started in the interchangeable lens1200in response to receiving the synchronization signal communication from the camera body1100. The system controller1130executes this process and other processes described later according to a lens communication control program as a computer program.

First, at step S1501, the lens controller1210acquires a current time point of a free-run timer used for time management in the interchangeable lens1200to store a time point at which the synchronization signal communication is performed (this time point is hereinafter referred to as “a synchronization signal communication time point”). The synchronization signal communication time point is stored to an internal memory in the lens controller1210or the memory1212.

Next, at step S1502, the lens controller1210determines whether or not a predetermined communication data length of the synchronization signal communication has been communicated, that is, whether or not the entire data communication (transmission and receipt) has been completed. If the entire data communication has not yet been completed, the lens controller1210repeats step S1502until the entire data communication is completed. On the other hand, if the entire data communication has been completed, the lens controller1210proceeds to step S1503.

At step S1503, the lens controller1210subtracts the synchronization signal communication delay time included in the received data of the synchronization signal communication from the synchronization signal communication time point stored at step S1501. This subtraction provides (sets) an in-lens image-capturing synchronization signal time point (that is, a time point of the image-capturing synchronization signal in the interchangeable lens1200) identical to the image-capturing synchronization signal time point in the camera body1100.

The above-described synchronization signal communication receiving process enables the interchangeable lens1200to acquire the in-lens image-capturing synchronization signal time point identical to the image-capturing synchronization signal time point in the camera body1100.

Next, with reference to a flowchart ofFIG. 16, description will be made of the above-mentioned lens angular velocity detection time period receiving process performed by the lens controller1210in the interchangeable lens1200for receiving the setting value communication of the lens angular velocity detection time period from the camera body1100.FIG. 16illustrates the lens angular velocity detection time period receiving process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. This process is started in the interchangeable lens1200in response to receiving the setting value communication of the lens angular velocity detection time period from the camera body1100.

First, at step S1601, the lens controller1210determines whether or not a predetermined communication data length of the setting value communication of the lens angular velocity detection time period has been communicated, that is, whether or not the entire data communication (transmission and receipt) has been completed. If the entire data communication has not yet been completed, the lens controller1210repeats step S1601until the entire data communication is completed. On the other hand, if the entire data communication has been completed, the lens controller1210proceeds to step S1602.

At step S1602, the lens controller1210sets an in-lens angular velocity detection time period depending on the setting value of the lens angular velocity detection time period included in the received data of the setting value communication performed at step S1601, and on the in-lens image-capturing synchronization signal time point calculated at step S1503inFIG. 15. The lens controller1210further acquires, from the angular velocity detector1208, the lens angular velocity in the in-lens angular velocity detection time period. Then, the lens controller1210adds the first detection time period ID included in the received data of the setting value communication performed at step S1601, and the angular velocity acquisition time point received in the object angular velocity communication to the acquired lens angular velocity, and stores these data to the internal memory or the memory1212. The lens controller1210is desirable to store that the follow shot assist process is active to the memory1212.

The above-described lens angular velocity detection time period receiving process enables the interchangeable lens1200to set the in-lens angular velocity detection time period identical to the motion vector detection time period in the camera body1100.

Next, with reference to a flowchart ofFIG. 17, description will be made of an object angular velocity receiving process performed by the lens controller1210in the interchangeable lens1200for receiving the object angular velocity from the camera body1100.FIG. 17illustrates the object angular velocity receiving process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. This process is started in the interchangeable lens1200in response to receiving the object angular velocity communication from the camera body1100.

First, at step S1701, the lens controller1210prepares (sets) the lens angular velocity and the second detection time period ID corresponding to the first detection time period ID stored at step1602inFIG. 16to a transmission buffer in order to transmit these data to the camera body1100.

Next, at step S1702, the lens controller1210starts transmitting the lens angular velocity and the second detection time period ID (that is, starts the object angular velocity communication) to the camera body1100and determines whether or not a predetermined communication data length of the object angular velocity communication has been communicated, that is, whether or not the entire data communication (transmission and receipt) has been completed. If the entire data communication has not yet been completed, the lens controller1210repeats step S1702until the entire data communication is completed. On the other hand, if the entire data communication has been completed, the lens controller1210proceeds to step S1703.

At step S1703, the lens controller1210stores the object angular velocity to the internal memory or the memory1212in preparation for the exposure start time.

The above-described object angular velocity receiving process enables the interchangeable lens1200to acquire the object angular velocity before the exposure start time in the camera body1100.

Next, with reference to a flowchart ofFIG. 18, description will be made of an exposure start time receiving process performed by the lens controller1210in the interchangeable lens1200for receiving the exposure start time from the camera body1100.FIG. 18illustrates the exposure start time receiving process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. This process is performed in the interchangeable lens1200in response to receiving an exposure start time communication from the camera body1100.

First, at step S1801, the lens controller1210determines whether or not the follow shot assist process is to be performed in the exposure process. For example, the lens controller1210determines this by referring to an area of the memory1212where the data is written at step S1602inFIG. 16. If the follow shot assist process is to be performed, the lens controller1210proceeds to step S1802. If the follow shot assist process is not to be performed, the lens controller1210proceeds to step S1804.

At step S1802, the lens controller1210as a predictor predicts a current object angular velocity at a current time point from the object angular velocity, the angular acceleration rate of the object and the angular velocity acquisition time point stored at step S1703inFIG. 17and the current time point. In other words, the lens controller1210calculates a predicted object angular velocity before still image capturing. Specifically, when T represents the current time point, V represents the current object angular velocity to be predicted, v, a and t respectively represent the object angular velocity, the angular acceleration rate of the object and the angular velocity acquisition time point, the lens controller1210performs a prediction calculation expressed by the following expression (1).
V=v+a*(T−t)   (1)

This expression (1) for the prediction calculation is an example, and other expressions or methods may be used.

Next, at step S1803, the lens controller1210controls the image-stabilization controller1209using the current object angular velocity to perform the follow shot assist process. For example, the lens controller1210acquires an image-stabilization amount (panning amount) g from the angular velocity detected by the angular velocity detector1208and calculates a follow shot assist control amount G by using the following expression (2).
G=V−g(2)

This expression (2) for calculating the follow shot assist control amount G is an example, and other expressions may be used. Controlling the image-stabilizing lens1204to move it in a direction opposite to and by the same amount as the follow shot assist control amount G enables acquiring a captured still image (image data) in which a moving object is still.

At step S1804, the lens controller1210performs an image-stabilization process using only the image-stabilization amount g from the angular velocity detector1208to reduce the image blur due to the user's hand jiggling.

The above-described exposure start time receiving process enables the interchangeable lens1200to transmit the follow shot assisted result of the follow shot assist process performed in the exposure process to the camera body1100, and enables the camera body1100to record the follow shot assisted result to the acquired image data.

Next, with reference to a flowchart ofFIG. 19, description will be made of a follow shot assisted result transmitting process performed by the lens controller1210in the interchangeable lens1200for transmitting the follow shot assisted result to the camera body1100.

FIG. 19illustrates the follow shot assisted result transmitting process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. This process is performed in the interchangeable lens1200in response to receiving a follow shot assisted result request from the camera body1100.

First, at step S1901, the lens controller1210prepares (sets) the follow shot assisted result such as the object angular velocity predicted at step S1802to the transmission buffer in order to transmit the follow shot assisted result to the camera body1100.

Next, at step S1902, the lens controller1210starts transmitting the follow shot assisted result to the camera body1100(that is, starts a follow shot assisted result communication) and determines whether or not a predetermined communication data length of the follow shot assisted result communication has been communicated, that is, whether or not the entire data communication (transmission and receipt) has been completed. If the entire data communication has not yet been completed, the lens controller1210repeats step S1902until the entire data communication is completed. On the other hand, if the entire data communication has been completed, the lens controller1210ends this follow shot assisted result transmitting process.

The above-described follow shot assisted result time receiving process enables the interchangeable lens1200to transmit the follow shot assisted result to the camera body1100.

The above-described processes enable the interchangeable lens1200to receive the object angular velocity to which an elapsed time from the time point of acquiring the lens angular velocity (angular velocity acquisition time point) to the start of the exposure is added, thereby achieving the follow shot assist process with higher accuracy.

Next, with reference to a time chart ofFIG. 20, description will be made of the follow shot assist process performed by the camera system10(the camera body1100and the interchangeable lens1200).FIG. 20illustrates process times in the follow shot assist mode when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process.

An image-capturing synchronization signal1001represents times at which the synchronization signal is output from the timing generator1104. An image-capturing charge accumulation1002represents time periods in which charge accumulation of the image sensor102is performed. Accumulated charges in the image sensor102are read out from an upper part thereof in response to each of the image-capturing synchronization signal1001. A synchronization signal communication1003represents times at which the synchronization signal communication is performed at step S1208inFIG. 12. A lens angular velocity detection time period communication1004represents times at which the lens angular velocity detection time period communication is performed at step S1209inFIG. 12.

An object angular velocity communication1005represents times at which the object angular velocity communication is performed at step S1308inFIG. 13.

A lens angular velocity detection time period1006represents the lens angular velocity detection time periods set at step S1602inFIG. 16. After the lens angular velocity detection time period ends, the lens angular velocity in that time period is calculated, and the lens angular velocity is stored with the first detection time period ID included in the setting value communication of the lens angular velocity detection time period and the angular velocity acquisition time point.

An angular velocity output1007represents outputs from the angular velocity detector1208. The lens controller1210samples the angular velocity output1007in the lens angular velocity detection time period1006. For example, when a synchronization signal communication1011is performed in response to the image-capturing synchronization signal1010, the lens controller1210calculates the in-lens image-capturing synchronization signal time point identical (corresponding) to the time point of the image-capturing synchronization signal1010.

Then, the lens angular velocity detection time period communication1012is performed. As a result, the setting value of the lens angular velocity detection time period calculated so as to be identical to a motion vector detection period (first time period)1013in the exposure setting process corresponding to a one previous image-capturing synchronization signal is transmitted to the interchangeable lens1200. Furthermore, in relation with the setting value of the lens angular velocity detection time period, a motion vector detection time period ID1020identical to the first detection time period ID allocated to the motion vector detection time period1013is transmitted to the interchangeable lens1200. This process enables the lens controller1210to set an in-lens angular velocity detection time period1014. The lens angular velocity acquired by the completion of the in-lens angular velocity detection time period1014is transmitted by an object angular velocity communication1015to the camera body1100with the second detection time period ID identical to the first detection time period ID acquired by the lens angular velocity detection time period communication1012. The follow shot assist controller1134calculates, when the first and second detection time periods ID are identical to each other, the object angular velocity by using the received lens angular velocity and the motion vector amount acquired in the motion vector detection time period1013.

Repeating the above-described processes enables the camera body1100to continuously transmit accurate object angular velocities to the interchangeable lens1200.

As described above, the image-capturing apparatus as a control apparatus of this embodiment includes the motion vector detector (1141), the calculator (follow shot assist controller1134) and the communicator (communication controller1133and camera I/F1120).

The motion vector detector is configured to detect the motion vector in the first time period (motion vector detection time period1013). The calculator is configured to set, depending on the first time period, the angular velocity detection time period in which the angular velocity is detected by the angular velocity detector (1208). The angular velocity detection time period is identical to the first time period or a predetermined time period corresponding to the first time period. The communicator is configured to transmit the angular velocity detection time period and the first ID information corresponding to the first time period in relation to each other. The communicator is further configured to receive the angular velocity detected in the angular velocity detection time period and the second ID information corresponding to that angular velocity in relation to each other. The calculator is configured to calculate the angular velocity of the object when the first ID information and the second ID information are identical to each other, by using the motion vector detected in the first time period corresponding to the first ID information and the angular velocity corresponding to the second ID information (steps S1306and S1307). The calculator may be configured to not calculate, when the first ID information and the second ID information are not identical to each other, the angular velocity information of the object by using the motion vector detected in the first time period corresponding to the first ID information and the angular velocity corresponding to the second ID information (step S1306).

The identity of the first ID information and the second ID information indicates that the communication (transmission and receipt) is performed with proper timing. On the other hand, a difference of the first ID information and the second ID information indicates that the communication is not performed with proper timing due to an insufficient communication band and a load increase. Thus, the camera body1100compares the first ID information transmitted to the interchangeable lens1200with the second ID information received from the interchangeable lens1200to determine whether or not the communication (transmission and receipt) is properly performed.

Furthermore, the lens apparatus (control apparatus) includes the communicator (lens controller1210and lens I/F1220) and the angular velocity detector (1208). The communicator is configured to receive the angular velocity detection time period set depending on the first time period that is the motion vector detection time period and the first ID information corresponding to the first time period in relation to each other. The angular velocity detector is configured to detect the angular velocity in the angular velocity detection time period. The communicator is configured to transmit the detected angular velocity and the second ID information corresponding to the detected angular velocity in relation to each other. The first ID information and the second ID information are identical to each other.

In this embodiment, the camera body1100transmits, to the interchangeable lens1200, the setting value of the lens angular velocity detection time period to which the first detection time period ID is added. Furthermore, the interchangeable lens1200transmits the lens angular velocity detected depending on the setting value of the lens angular velocity detection time period, with the second detection time period ID.

This communication enables the camera body1100to determine the detection time of the angular velocity, depending on the identity of the first and second detection time period IDs, which achieves a lens-interchangeable camera system having a follow shot assist function capable of accurately calculating the object angular velocity.

Next, description will be made of a fourth embodiment (Embodiment 4) of the present invention. This embodiment provides a follow shot assist function capable of further accurately calculating the object angular velocity. A basic configuration of this embodiment is the same as that of Embodiment 3, and constituent elements common to those in Embodiment 3 are denoted by the same reference numerals as those in Embodiment 3.

Embodiment 3 does not perform the object angular velocity calculation (step S1307) when the first and second detection time period IDs are not identical to each other. However, such a difference of the first and second detection time period IDs may indicate a situation that the communication with proper timing cannot be performed due to an insufficient communication band and a load increase. In such a situation, using data previously acquired (that is, past data) or reperforming the communication (that is, performing a retry process) may enable a successful object angular velocity calculation. Thus, the camera system of this embodiment performs the retry process when the first and second detection time period IDs are not identical to each other.

With reference to a flowchart ofFIG. 21, description will be made of an exposure setting process performed by the system controller1130and the follow shot assist controller1134in the camera body1100in this embodiment.FIG. 21illustrates the exposure setting process performed when the camera body1100is in the live-view image-capturing mode and the interchangeable lens1200attached thereto is compatible with the follow shot assist process. As in Embodiment 3, the exposure setting process is performed for every frame in the live-view image-image capturing mode in order to perform the exposure control for the next frame. Steps S2101to S2105inFIG. 21are common to steps S1301to S1305inFIG. 13, and therefore description thereof is omitted.

At step S2106, the follow shot assist controller1134determines whether or not the motion vector detection time period ID (that is, the first detection time period ID) corresponding to the motion vector detection time period in which the motion vector to be used is detected is identical to the second detection time period ID corresponding to the lens angular velocity received from the interchangeable lens1200. If these detection time period IDs are identical to each other, the follow shot assist controller1134proceeds to step S2110. If these detection time period IDs are not identical to each other, the follow shot assist controller1134proceeds to step S2107.

At step S2107, the follow shot assist controller1134determines whether or not multiple second detection time period IDs as past data previously received from the interchangeable lens1200include one identical to the motion vector detection time period ID corresponding to the motion vector detection time period in which the motion vector to be used is detected. If the past second detection time period IDs includes the one (hereinafter referred to “a specific past ID”) identical to the motion vector detection time period ID, the follow shot assist controller1134resets the lens angular velocity corresponding to the specific past ID as a lens angular velocity for calculation and proceeds to step S2110. On the other hand, if the second detection time period IDs do not include the specific past ID, the follow shot assist controller1134proceeds to step S2118.

At step S2108, the follow shot assist controller1134re-receives, that is, reacquires the lens angular velocity as a second angular velocity with a third detection time period ID (third ID information) from the interchangeable lens1200.

Next, at step S2109, the follow shot assist controller1134determines whether or not the reacquired third detection time period ID reacquired at step S2108is identical to the motion vector detection time period ID corresponding to the motion vector detection time period in which the motion vector to be used is detected. If these detection time period IDs are identical to each other, the follow shot assist controller1134proceeds to step S2110. If these detection time period IDs are not identical to each other, the follow shot assist controller1134proceeds to step S2111.

At step S2110, the follow shot assist controller1134calculates the object angular velocity using the lens angular velocity and the lens information such as the focal length received from the interchangeable lens1200and on the motion vector amount input from the image processor1140. As in Embodiment 3, the object angular velocity includes not only the angular velocity but also the angular acceleration rate. The follow shot assist controller1134inputs the calculated object angular velocity to the communication controller1133. As in Embodiment 3, the object angular velocity is provided with the angular velocity acquisition time point corresponding to the lens angular velocity used for calculating the object angular velocity.

At step S2111, the communication controller1133performs an object angular velocity communication in order to transmit the object angular velocity with the second detection time period ID to the interchangeable lens1200and then returns to step S2101.

The above-described exposure setting process enables the camera body1100to perform the exposure control for the next frame and to set the lens angular velocity detection time period to be transmitted in response to a next image-capturing synchronization signal to the interchangeable lens1200. Furthermore, the exposure setting process enables the camera body1100to transmit the object angular velocity to the interchangeable lens1200and to receive the lens angular velocity from the interchangeable lens1200.

As described above, in this embodiment, the communicator (communication controller1133and camera I/F1120) is desirably configured to receive the second angular velocity detected in a different time period from the lens angular velocity detection time period and the third ID information corresponding to the second angular velocity in relation to each other. The calculator (follow shot assist controller1134) is desirably configured to calculate the object angular velocity when the first ID information and the second ID information are not identical to each other and the first ID information and the third ID information are identical to each other, by using the second angular velocity corresponding to the third ID information. In other words, the calculator is desirably configured to calculate the object angular velocity using the motion vector detected in the first time period corresponding to the first ID information and the second angular velocity corresponding to the third ID information. The second angular velocity corresponding to the third ID information is desirably detected in a time period after the lens angular velocity corresponding to the second ID information is detected.

The calculator is desirably configured to cause the angular velocity detector to reacquire the lens angular velocity as a third angular velocity when the first ID information is not identical to the second ID information and the first ID information is not identical to the third ID information (step S2108). The communicator is desirably configured to receive the reacquired angular velocity and fourth ID information corresponding to the reacquired angular velocity in relation to each other. The calculator is desirably configured to calculate the object angular velocity when the first ID information and the fourth ID information are identical to each other, by using the motion vector detected in the first time period corresponding to the first ID information and the reacquired angular velocity corresponding to the fourth ID information.

The calculator is further desirably configured not to calculate the object angular velocity by using the motion vector detected in the first time period corresponding to the first ID information and the reacquired angular velocity corresponding to the fourth ID information when the first ID information and the fourth ID information are not identical to each other (step S2109).

Also in this embodiment, the camera body1100transmits, to the interchangeable lens1200, the setting value of the lens angular velocity detection time period to which the first detection time period ID is added. Furthermore, the interchangeable lens1200transmits the angular velocity detected depending on the setting value of the lens angular velocity detection time period, with the second detection time period ID. This communication enables the camera body1100to determine the detection time of the angular velocity, depending on the identity of the first and second detection time period IDs. In addition, the camera body1100performs the retry process when the first and second detection time period IDs are not identical to each other. Thereby, this embodiment achieves a lens-interchangeable camera system having a follow shot assist function capable of more accurately calculating the object angular velocity.

Other Embodiments

This application claims the benefit of Japanese Patent Application No. 2016-069915, filed on Mar. 31, 2016 and Japanese Patent Application No. 2016-145210, filed on Jul. 25, 2016, which are hereby incorporated by reference herein in their entirety.