JP5517482B2 - Imaging apparatus and camera system - Google Patents

Description

  The present invention relates to a camera system that includes an imaging device and one or more slave strobes, and more particularly to imaging control when a communication failure occurs at the light emission timing.

  Conventionally, in a camera system including an imaging device and one or more slave strobes, it has been necessary to control the slave strobe with the imaging device so that the slave strobe emits light at an appropriate light emission timing and light emission amount. For this reason, communication of information necessary for strobe control has been performed by wired communication in which an imaging device and a slave strobe are connected by a cable, or wireless communication in which electromagnetic waves or light is used. The wireless communication system is easy to handle because it is not necessary to connect with a cable as compared with a wired communication system. For example, in Patent Document 1, wireless communication is performed so as to operate in synchronization between a plurality of devices. Wireless strobe systems have been proposed. However, in any of the wired communication system and the wireless communication system, there has been a problem that proper strobe control cannot be performed when a communication failure occurs. In particular, wireless communication systems that use electromagnetic waves, light, etc. communicate when there are obstacles in the communication path, there are disturbances that emit electromagnetic waves in the same frequency band, or when strong light enters during communication. An error occurred, and the reliability of communication was inferior to that of the wired communication system.

  Therefore, in the wireless communication system, the reliability of communication is ensured by providing an error correction mechanism or performing packet retransmission processing.

JP 2000-089304 A

  However, appropriate strobe control could not be performed simply by providing an error correction mechanism or performing packet retransmission processing.

  In other words, communication is performed from the master device to the slave device in order to perform shooting, but if a communication failure occurs at this time, for example, the device may not emit light properly or may not emit light. In some cases, light emission was not performed at the light emission timing. For this reason, there has been a problem that images intended by the user are not captured during flash photography.

  An object of the present invention is to make it possible to obtain a captured image reflecting the user's intention even when communication failure occurs during flash photography.

In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus capable of communicating with a strobe device via communication means, and transmits information indicating start of main flash via the communication means. A measuring means for measuring a response time from the transmission to the apparatus until receiving the reception completion information indicating that the information for instructing the start of the main light emission is received from the strobe apparatus, and an exposure control means for performing exposure control If, anda light emission amount calculating means for calculating a main light emission amount of the flash device, towards the case where the response time is not the less than the predetermined time than is less than the predetermined time, the exposure control means, dew The light emission time is lengthened and at least one of the photographing sensitivity and the aperture value is set to a value for decreasing the exposure, and the light emission amount calculating means increases the main light emission amount.

The camera system according to the present invention is a camera system including an imaging device and a strobe device, wherein communication means for performing communication between the imaging device and the strobe device, and the imaging device includes the communication means. Response time from the time when the information indicating the start of the main flash is transmitted to the strobe device via the receiver until the reception completion information indicating that the information indicating the start of the main flash is received is received from the strobe device Measuring means for measuring exposure, exposure control means for performing exposure control, and light emission amount calculating means for calculating the main light emission amount of the strobe device, and the predetermined time than when the response time is less than a predetermined time. better if not below the time, the exposure control means in the direction of the value of reducing the exposure of at least one of the imaging sensitivity and aperture with a longer exposure time, the light emission amount Starring Means is characterized by increasing the main light emission amount.

  According to the present invention, it is possible to obtain a captured image reflecting the user's intention even when communication failure occurs during flash photography.

1 is a schematic diagram of a camera system including a digital camera and an external strobe according to an embodiment of the present invention. It is a mainly optical block diagram of the camera body 100 in FIG. It is a block diagram of the external strobe 101 in FIG. FIG. 2 is a block diagram of a camera body 100 and a lens unit 123 in FIG. 1. FIG. 2 is a circuit block diagram of an external strobe 101 in FIG. 1. 2 is a timing chart when communication is normally performed during strobe control (strobe shooting control) in the camera system of FIG. 1. 2 is a timing chart when a communication failure occurs during strobe control (strobe shooting control) in the camera system of FIG. 1. 6 is a flowchart illustrating a communication control process performed by the camera body 100 in FIG. 4. It is a flowchart which shows the procedure of the flash photography control process performed by the camera system of FIG. It is a flowchart which shows the procedure of the main light emission request | requirement and light emission amount notification process based on embodiment of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram of a camera system including a digital camera (imaging device) and an external strobe (strobe device) according to an embodiment of the present invention.

  A camera body 100 incorporating a wireless communication device is fixed on a tripod 104. A lens unit 123 is attached to the camera body 100. As with the camera body 100, the external strobe 101 has a built-in wireless communication device.

  The camera body 100 and the external strobe 101 perform wireless communication by a method such as IEEE 802.15.4, which is a known wireless communication standard. FIG. 1 shows a case where strobe shooting is performed on a subject 102 with a screen 103 as a background in a photo studio.

  In this embodiment, the camera body 100 serves as a master device, and by controlling the external strobe 101 that is a slave device, synchronized shooting in which the exposure of the camera and the strobe light emission are synchronized can be performed.

  FIG. 2 is a mainly optical configuration diagram of the camera body 100 in FIG.

  The main mirror 116 is obliquely moved to or removed from the photographing optical path in accordance with an observation state in which light from the subject is guided to the focusing plate 115 and a photographing state in which the light is guided to the imaging sensor 159. The main mirror 116 is a half mirror, and transmits about half of the light beam from the subject to a focus detection optical system described later.

  The focus plate 115 is disposed on the planned image plane of the lens unit 123. The pentaprism 110 changes the finder optical path. The photographer can observe the photographing screen by observing the focus plate 115 through the finder eyepiece 114 from the window of the eyepiece 113.

  The imaging lens 111 and the photometric sensor 112 are for measuring the luminance of the subject in the imaging screen. The imaging lens 111 conjugates the focusing plate 115 and the photometric sensor 112 via the reflected light path in the pentaprism 110. It is related.

  A shutter 119 is disposed in front of the CMOS or CCD image sensor 159. The subject is imaged by the imaging sensor 159, and the output signal is A / D converted to take out digital data. The digital data is further processed to generate image data in JPEG format or the like and record it on a recording medium such as a CF card or an SD card.

  The sub mirror 117 guides the light beam from the subject toward the focus detection unit 120 provided below. The focus detection unit 120 includes a secondary imaging mirror, a secondary imaging lens, a focus detection sensor, and the like.

  The focus detection unit 120 realizes an automatic focus detection device by detecting the focus state of the subject in the imaging screen by a known phase difference detection method and controlling the focus adjustment mechanism of the photographing lens.

  The lens mount contact 121 is an interface between the camera body 100 and the lens unit 123 attached to the camera body 100. The lens unit 123 includes a plurality of photographing lenses, and a part of the lens unit 123 can be moved back and forth on the optical axis by the lens driving motor 124 to adjust the focus position of the imaging screen. Further, the lens unit 123 includes a photographic lens aperture, and the lens aperture driving motor 122 is driven so that the photographic lens aperture can be adjusted to a desired aperture diameter.

  The wireless antenna 140 transmits / receives data using radio waves to / from camera accessories such as an external strobe 101 and a remote controller.

  FIG. 3 is a configuration diagram of the external strobe 101 in FIG.

  The external strobe 101 performs light emission control according to data from the camera body 100. The wireless antenna 133 transmits / receives data to / from the camera body 100 using radio waves. A xenon tube (Xe tube) 136 as a light emitting means flashes using electric energy accumulated in a main capacitor (not shown).

  The reflector (reflective shade) 139 and the Fresnel lens 137 each have a function of efficiently condensing the light emitted from the xenon tube 136 toward the subject. The angle adjustment mechanism 130 is for changing the angle of the light emitting unit, and the clip-on connector 132 is for mechanically fixing the external strobe 101 to the camera body 100, the tripod 104, or the like.

  A light transmission member 134 such as a glass fiber guides light emitted from the xenon tube 136 to a light receiving element 131 as a first light receiving means such as a photodiode. Then, the amount of light at the time of preliminary light emission (hereinafter, also referred to as pre-light emission) performed before the main light emission of the external strobe 101 is measured directly.

  The light receiving element 138 such as a photodiode is also a second light receiving means for monitoring the light emitted from the xenon tube 136. Based on the output of the light receiving element 138, the light emission current of the xenon tube 136 is limited to control flat light emission. The light guides 135a and 135b are integrated with the reflection plate 139, and reflect and guide the light emitted from the xenon tube 136 to the light receiving element 138 or 131.

  FIG. 4 is a block diagram of the camera body 100 and the lens unit 123 in FIG.

  The camera microcomputer 158 is a main microcomputer that performs various controls of the camera body 100, and performs power control, switch control, lens control, photometry control, distance measurement control, shutter control, wireless communication control, and the like.

  Connected to the camera microcomputer 158 are a power supply circuit 163, a switch array 170 such as SW1 and SW2, an oscillation circuit 154, a wireless communication circuit 147, a focus detection circuit 148, a photometry circuit 149, an LCD drive circuit 150, a shutter control circuit 155, and the like. ing. The camera microcomputer 158 is connected to a motor control circuit 157, an image processing engine 162, and the like.

  The camera microcomputer 158 and the lens microcomputer 152 serving as a lens control circuit disposed in the lens unit 123 transmit signals via a mount contact. The external flash 101 exchanges wireless communication packets generated by the camera microcomputer 158 via the wireless communication circuit 147 and the wireless antenna 140, so that the flash microcomputer 184 on the external flash 101 side (see FIG. 5 described later). The signal is transmitted.

  The camera microcomputer 158 is driven by the clock generated by the oscillation circuit 154, and performs accurate time management by counting this clock. The camera microcomputer 158 controls the timing in the operation sequence of the entire camera body 100 and the timing in the communication sequence with the external strobe 101 or the remote controller.

  The focus detection circuit 148 performs accumulation control and readout control of the distance measuring sensor according to the signal of the camera microcomputer 158, and outputs each pixel information to the camera microcomputer 158. The camera microcomputer 158 A / D converts this information and performs focus detection by a known phase difference detection method.

  The camera microcomputer 158 performs focus adjustment of the photographing lens by exchanging signals with the lens microcomputer 152 based on the focus detection information.

  The photometry circuit 149 outputs an output from the photometry sensor 112 to the camera microcomputer 158 as a luminance signal of the subject. The photometry circuit 149 outputs a luminance signal in each of a steady state in which strobe light is not pre-flashed toward the subject and a pre-flash state in which pre-flash is emitted. The camera microcomputer 158 performs A / D conversion of the luminance signal, calculates exposure control parameters (aperture value, shutter speed, shooting sensitivity) for exposure control during shooting, and calculates the amount of light emission during main flash.

  The shutter control circuit 155 controls the two shutter drive magnets constituting the focal plane shutter in accordance with a signal from the camera microcomputer 158, travels the shutter curtain, and performs an exposure control operation.

  The motor control circuit 157 controls the motor in accordance with a signal from the camera microcomputer 158 to perform up / down of the main mirror and charge of the shutter.

  In the switch array 170, SW1 is turned on by the first stroke of the release button, and serves as a switch for starting photometry and AF. SW2 is turned on by the second stroke of the release button and serves as a switch for starting an imaging operation. The camera microcomputer 158 detects signals from SW1 and SW2 and other operation members of the camera body 100 (not shown).

  The LCD drive circuit 150 controls display on the in-finder LCD 141 and the monitor LCD 142 in accordance with a signal from the camera microcomputer 158.

  The image processing engine 162 is a processor that mainly performs digital image processing, and controls the imaging sensor 159 and controls image processing, image display, image recording, and the like by a program stored in the FROM 169.

  When there is an imaging control request from the camera microcomputer 158, the image processing engine 162 performs accumulation control and readout control of the imaging sensor 159 via the timing generator (TG) 160.

  The image signal read from the image sensor 159 is converted from analog to digital by the AD converter 161, input to the image processing engine 162, and temporarily stored in the DRAM 168.

  The image signal temporarily stored in the DRAM 168 is read again by the image processing engine 162, and image processing such as known color interpolation processing, white balance processing, and gamma processing is performed, and finally converted into digital image data such as JPEG. Is done. When the digital image data is generated, it is temporarily stored again in the DRAM 168, displayed on the TFT display device 166 for quick review, and further recorded on the recording medium 167.

  When the camera body 100 is connected to an external device such as a PC via the external interface 165, the image data is recorded on the recording medium 167 and transmitted to the external device.

  Next, the configuration of the lens unit 123 will be described.

  The camera body 100 and the lens unit 123 are electrically connected to each other via a lens mount contact 121. The lens mount contact 121 includes a contact for supplying power to the photographing lens and a signal contact for communicating with the lens microcomputer 152 as lens control means.

  The lens microcomputer 152 operates the focus drive motor control circuit 144 connected to the focus drive motor 143 and the aperture drive motor control circuit 145 connected to the stop 146 to control the focus adjustment and the stop of the lens. The lens microcomputer 152 is connected to the focus position detection circuit 151 and the switch array 153.

  FIG. 5 is a circuit block diagram of the external strobe 101 in FIG.

  The DC / DC converter 186 boosts the voltage of the battery 180 to several hundred volts. Main capacitor 187 stores electrical energy. Resistors 190 and 191 divide the voltage of the main capacitor 187 into a predetermined ratio.

  The first coil 188 limits the light emission current. The first diode 189 absorbs a counter electromotive voltage generated when light emission is stopped. The second coil 198 limits the light emission current. The second diode 217 absorbs a counter electromotive voltage generated in the second coil 198 when light emission is stopped. A trigger generation circuit 205 and a light emission control circuit 206 such as an IGBT are connected to the xenon tube 136.

  The thyristor 199 is a switching element for bypassing the second coil 198. When improving the stop controllability at the time of light emission stop at the time of flash light emission, the light emitting current is prevented from flowing through the second coil 198. To bypass.

  The resistor 196 causes a current to flow through the gate that is the control pole of the thyristor 199 in order to turn on the thyristor 199. The resistor 200 for stabilizing the gate potential prevents the thyristor 199 from being turned on when noise is applied to the gate of the thyristor 199 when the thyristor 199 is off.

  Capacitor 202 turns on thyristor 199 rapidly. The noise absorbing capacitor 201 prevents the thyristor 199 from being turned on when noise is applied to the gate of the thyristor 199 when the thyristor 199 is off. The transistor 193 switches the gate current of the thyristor 199.

  The transistor 204 switches the transistor 193. Resistors 192 and 203 are connected to the transistor 193, and resistors 194 and 195 are connected to the transistor 204. The data selector 207 selects D0, D1, and D2 based on the combination of the two inputs Y0 and Y1, and outputs them to Y.

  The comparator 208 is for controlling the luminous intensity of flat light emission. The comparator 209 is for controlling the light emission amount during flash emission. The light receiving element 138 is a photodiode which is a light receiving sensor for flat light emission control, and monitors the light output of the xenon tube 136 which is a light emitting means.

  The photometry circuit 210 amplifies a minute current flowing through the light receiving element 138 and converts the photocurrent into a voltage. The light receiving element 131 is a photodiode which is a light receiving sensor for controlling flash emission, and monitors the light output of the xenon tube 136 which is a light emitting means. The photometric integration circuit 211 logarithmically compresses the photocurrent flowing through the light receiving element 131 and compresses and integrates the light emission amount of the xenon tube 136.

  The strobe microcomputer 184 controls the operation of the entire strobe. A display device 183 such as a liquid crystal display is display means for displaying the operating state of the external strobe 101.

  The switch array 216 includes a power control main switch, a backlight lighting switch, a light emission mode changeover switch, and the like. The LED 181 displays the completion of charging of the strobe. The LED 182 displays that the external strobe 101 has been photographed with an appropriate amount of light.

  The motor 215 controlled by the motor control circuit 214 moves the xenon tube 136 and the reflector 139 in accordance with the focal length of the lens unit 123 mounted on the camera body 100, and sets the irradiation angle. An oscillation circuit 213 and a wireless communication circuit 185 are also connected to the strobe microcomputer 184.

  Next, each terminal of the flash microcomputer 184 will be described.

  CNT is a control output terminal that controls the charging operation by the DC / DC converter 186. YIN is an input terminal for detecting the output state of the data selector 207, and INT is an integration control output terminal of the photometric integration circuit 211. AD0 is an A / D conversion input terminal for reading an integrated voltage indicating the light emission amount of the photometric integration circuit 211, and DA0 is a D / A output terminal for outputting a comparator voltage of the comparators 208 and 209. .

  Y0 and Y1 are selection state setting output terminals of the data selector 207, TRIG is a light emission trigger generation output terminal, and SCR_CTRL is a control output terminal of the thyristor 199.

  Here, the camera microcomputer 158 functions as a generation unit that generates a synchronization command packet and an addition unit that adds light emission related information required when the external strobe 101 as a slave device emits light to the synchronization command packet.

  The wireless communication circuit 147 and the wireless antenna 140 function as a transmission unit that sequentially transmits the synchronization command packet.

  The wireless communication circuit 185 and the wireless antenna 133 function as a receiving unit that receives a synchronization command packet transmitted from the camera body 100 serving as a master device.

  Further, the flash microcomputer 184 functions as a light emission control unit that performs light emission control based on the light emission related information added to the received synchronization command packet.

  Further, when receiving the synchronization command packet, the wireless communication circuit 185 and the wireless antenna 133 function as notification means for notifying the master device that reception has been completed.

  Further, the wireless communication circuit 147 and the wireless antenna 140 function as an acquisition unit that acquires a reception completion notification from the slave device.

  In addition, the camera microcomputer 158 functions as a measurement unit that measures the time from when the transmission of the synchronization command packet is completed until the reception completion notification is acquired.

  The camera microcomputer 158 functions as a changing unit that changes the trailing curtain travel start timing based on the delay time obtained by the measuring unit after the synchronization command packet is transmitted from the master device during strobe light emission.

  In addition, the camera microcomputer 158 performs the following calculation in response to the exposure amount change accompanying the change in the trailing curtain travel start timing. That is, the camera microcomputer 158 makes the same dimming-related parameters and exposure necessary to make the light quantity ratio of strobe light and natural light the same when shooting without changing the trailing curtain travel start timing. Recalculate necessary exposure-related parameters. Then, the camera microcomputer 158 performs synchronous shooting control based on the recalculation result.

  Next, a strobe shooting sequence when the camera body 100 and the external strobe 101 are in a one-to-one relationship as shown in FIG. 1 will be described with reference to FIGS.

  FIG. 6 is a timing chart when communication is normally performed during strobe control (strobe shooting control) in the camera system of FIG. FIG. 7 is a timing chart when communication failure occurs during strobe control (strobe shooting control) in the camera system of FIG. In FIG. 7, a communication failure occurs at the time of the main light emission request and the light emission amount notification. When FIG. 6 is compared with FIG. 7, the accumulation time of the image sensor 159 in FIG. Has increased. In FIG. 7, the main light emission amount also increases as the accumulation time of the image sensor 159 increases.

  In the camera system of FIG. 1, first, the camera body 100 and the external strobe 101 are registered in advance as communication partners by known wireless pairing. When the camera body 100 is turned on and set to the flash emission mode, the camera body 100 controls the wireless communication circuit 147 to set a channel to be used for searching from the camera body 100. It is set in a state where it can respond.

  When the camera main body 100 finds the external strobe 101 by the search, the camera main body 100 starts issuing a beacon packet periodically as a network coordinator to start up the network.

  The external strobe 101 functions as a network device, and is in a state where communication is possible at any time by establishing a link with each other as a communication partner of the camera body 100.

  Next, communication control of the camera body 100 in the camera system of FIG. 1 will be described. FIG. 8 is a flowchart illustrating a communication control process performed by the camera body 100. This flow is executed under the control of the camera microcomputer 158, and each processing step is denoted by a symbol S.

  In the standby state, when a notification request is generated, the camera microcomputer 158 starts transmitting request data (S101). In addition to using the request data as a timing notification for control, if there is information necessary for the control, the information can be added.

  In the case of this embodiment, as a request for starting the main flash, data necessary for the main flash control called the flash amount is added to the timing notification called the main flash request, and communication is performed from the camera body 100 to the external strobe 101. It is supposed to be.

  In addition to that, request data such as timing notification + control data as described above may be configured depending on design requirements.

  Thereafter, the camera microcomputer 158 waits for the completion of transmission (S102), and measures the time from when the transmission is completed until the Ack notification (reception completion information notifying that data has been received normally) from the external strobe 101 comes. Therefore, delay time measurement is started (S103). Note that the delay time is measured every time request data is transmitted, and the delay time measured every time the request data is transmitted is defined as a first delay time. In addition, the time from the first data transmission after receiving the Ack notification corresponding to the previous data transmission until the next Ack notification is received is measured as the second delay time. In other words, the second delay time is a response time from when the camera body 100 starts to transmit certain information to the external strobe 101 until the external strobe responds to the information. Similarly, when the first data transmission is performed after the power source of the camera body 100 is turned on, the time until the next Ack notification is received is measured as the second delay time.

  The maximum waiting time until the Ack notification comes is initialized once when the system such as the power supply On is activated, and is a predetermined time calculated from the processing speed, communication speed, etc. of the CPU of the camera microcomputer 158. As will be described later, if the camera microcomputer 158 receives an Ack notification before the maximum waiting time elapses, the camera microcomputer 158 determines that communication is normally performed, and if the Ack notification cannot be received until the maximum waiting time elapses. It is determined that the communication is not normally performed, and the request data is transmitted again. In the present embodiment, description will be made assuming that the maximum waiting time is set to a time of about several tens of milliseconds.

  The camera microcomputer 158 monitors whether or not the first delay time during the measurement exceeds the waiting maximum time (S108). If the first delay time exceeds the maximum waiting time, the camera microcomputer 158 regards it as a time-out waiting for Ack notification and enters preparation for re-transmission for transmitting the previous request data to the strobe again (S109). ). When request data is transmitted again, measurement of the first delay time is newly started in S103. Therefore, measurement of the first delay time up to that point from the end of S108 to the start of S103 is performed. To stop.

  When the Ack notification is received (S104), the camera microcomputer 158 stops the first and second delay time measurement (S105). If the second delay time measurement result at that time is longer than the maximum waiting time, the camera microcomputer 158 calculates a difference time of “(second delay time measurement result) − (maximum waiting time)”. Then, it is set as the delay time for trailing curtain travel (S106). Further, if the second delay time measurement result at that time does not exceed the maximum waiting time, that is, if it is less than the predetermined time, the camera microcomputer 158 sets the trailing curtain travel delay time as 0 ( S106).

  Furthermore, the average value of the second delay time measurement result and the maximum waiting time is reset as the waiting maximum time after the next time (S107), so that the latest communication state is taken into consideration, and the waiting time maximum after the next time. Change the value to a value that is as high as possible.

  However, when the system is terminated, such as when the power is turned off (off), it is not necessary to take into account the most recent communication state. The communication process ends here.

  FIG. 9 is a flowchart showing the procedure of the flash photographing control process executed by the camera system of FIG.

  In the standby state (S201), when Sw2 of the camera body 100 is turned on (S202), the camera body 100 sends a Sw2On notification to the external strobe 101. In response to this notification, Ack + full information is notified from the external strobe 101 to the camera body 100 (S203). In the standby state, Sw1 of the camera main body 100 is turned on, and shooting preparation operations such as photometry and AF are performed, and exposure control parameters (aperture value, shutter speed, shooting sensitivity) at the time of shooting are calculated based on the result. It shows the state that was done.

  The camera microcomputer 158 determines whether or not the external strobe 101 is in a charging state capable of emitting light based on the notified charge completion information (S204). A necessary pre-emission request notification for pre-emission is performed (S205).

  When the Ack notification corresponding to the pre-flash request notification is returned from the external strobe 101, the camera microcomputer 158 accumulates the photometric sensor 112 in accordance with the pre-flash of the external strobe 101 (S206), and based on the accumulation result, A light emission amount calculation at the time of light emission is performed (S207).

  Next, the camera microcomputer 158 starts running the shutter front curtain, starts accumulation of the image sensor 159, and starts exposure (S208). Then, the camera microcomputer 158 makes a main light emission request, which is information for instructing the start of the main light emission and the notification of the light emission amount obtained above to the external strobe 101 at a predetermined timing after the start of the front curtain travel (S209). ). Even when the communication is normally performed, if the first delay time from when the main light emission request and the light emission amount notification are performed until the Ack notification returns is longer than the predetermined time, the shutter destination There is a time loss between the completion of the curtain travel and the actual light emission. For this reason, depending on the shutter speed at the time of actual shooting, the main flash may be emitted during the period when the shutter 119 is fully open from when the shutter front curtain travel is completed to when the shutter rear curtain starts to travel (shutter fully open time). This is not performed, and uneven exposure occurs in the captured image. Therefore, when it is assumed that the first delay time from when the main light emission request and the light emission amount notification are made to when the Ack notification is returned is longer than a predetermined time, before the shutter front curtain starts to travel. The main light emission request and the light emission amount notification may be performed.

  FIG. 10 is a flowchart showing a procedure of the main light emission request and light emission amount notification processing executed in S209 of FIG. 9, and the basic notification processing flow is the same as the communication control of the camera body 100 described in FIG. It is the same.

  When the main light emission request and the light emission amount notification request are generated, the camera microcomputer 158 starts transmitting data to the external strobe 101 (S301). The amount of light emitted to the external strobe 101 first after pre-emission is obtained by calculating the amount of emission during pre-emission.

  Next, the camera microcomputer 158 waits for the completion of transmission (S302), and starts the first and second delay time measurement for measuring the time from when the transmission is completed until the Ack notification is received from the external strobe 101. (S303).

  The maximum waiting time until the Ack notification is received is the same as that described in the communication control processing of the camera body 100 in FIG. 8, and the camera microcomputer 158 determines the maximum waiting time as the first delay time during measurement. Whether or not it exceeds is monitored (S308). If exceeded, the camera microcomputer 158 regards it as an Ack notification timeout, and temporarily sets the second delay time at that time as the trailing curtain travel delay time (S309).

  Next, the camera microcomputer 158 performs the light emission amount recalculation using the curtain travel delay time thereafter (S310). Specific light emission amount recalculation will be described later.

  When the light emission amount recalculation result is obtained, the camera microcomputer 158 updates the result as light emission amount data for transmission (S311), and again sends a re-flash request and a light emission amount notification to the external strobe 101. This is performed (S301).

  That is, every time re-notification is performed due to a timeout waiting for Ack, the notified light emission amount is a recalculated value. In FIG. 7, since a communication failure has occurred, the light emission amount recalculation is performed three times, and the re-flash request and the light emission amount notification are performed three times to notify the recalculated light emission amount.

  When the Ack notification is received (S304), the camera microcomputer 158 stops the second delay time measurement so far (S305). Then, as shown in FIG. 7, if the second delay time measurement result at that time is longer than the maximum waiting time, the camera microcomputer 158 displays “(second delay time measurement result) − (maximum waiting time)”. Is set as the trailing curtain travel delay time (S306). Further, as shown in FIG. 6, if the second delay time measurement result at that time is less than the waiting maximum time, the camera microcomputer 158 sets the trailing curtain travel delay time as 0 (S306).

  Further, the camera microcomputer 158 resets the average value of the second delay time measurement result and the maximum waiting time as the maximum waiting time after the next time (S307), so that the latest communication state is taken into account. Change the maximum waiting time thereafter to a value that is as reasonable as possible. This completes the re-emitted light emission request and the emitted light amount notification process.

  Returning to FIG. 9 again, after the main flash of the external flash 101 (S210), the camera microcomputer 158 starts a timer for controlling the trailing curtain travel start timing (S211). Usually, the set time of this timer is set in advance according to the photographing shutter speed, and if the delay time for trailing curtain travel is 0, it is set in advance. That is, the set time of the timer is set so that the time (exposure time) from the end of passing the front curtain to the start of passing the rear curtain in any line of the image sensor 159 becomes the shooting shutter speed.

  However, if the trailing curtain travel delay time is set to a value other than 0, the time is also set to the timer setting time. In other words, the shutter opening time is extended by delaying the trailing curtain travel start timing as much as the time when the light emission start timing is delayed. As a result, even if the main light emission is delayed from the normal timing, it falls within the shutter fully open time, and can be reflected in the captured image.

  Then, the camera microcomputer 158 waits for the set time of the timer to elapse (S212), and starts the trailing curtain travel when the set time elapses (S214).

  Next, when the rear curtain travel start timing is delayed, the exposure time is also changed. Therefore, the camera microcomputer 158 then determines the final shooting sensitivity value based on the rear curtain travel delay time. An operation is performed (S215).

  Then, the camera microcomputer 158 reads image data from the image sensor 159 (S216), generates an image based on the final photographing sensitivity value calculation result (S216), and ends the strobe photographing control process.

  Next, the recalculation of the light emission amount during the main light emission and the final photographing sensitivity value calculation method will be described.

First, a corrected shutter speed control value obtained by multiplying the delay time for trailing curtain travel at that time by the shutter speed control value for internal control per unit time is obtained. That is, the corrected shutter speed control value indicates the amount of shutter speed correction corresponding to the time when the light emission start timing is delayed. Therefore, the actual shooting shutter speed is a time obtained by adding the length of the shutter speed corresponding to the corrected shutter speed control value to the shooting shutter speed when the light emission start timing is not delayed.
(Corrected shutter speed control value)
= (Delay time for rear curtain travel (msec) x shutter speed control value for internal control per 1 msec)
Even if the exposure time (shutter speed) is changed, the amount of light emitted during main flash is recalculated in order to maintain the light intensity ratio between the original strobe light and natural light obtained by the light emission amount calculation during pre-flash. Is. Then, it is obtained by adding the light emission amount corresponding to the corrected shutter speed control value obtained by the above calculation to the original light emission amount (the light emission amount obtained by the light emission amount calculation at the time of pre-light emission). The amount of light emission corresponding to the corrected shutter speed control value is determined based on the amount of natural light for the exposure time that is increased by the correction, and the original strobe light and natural light amount ratio obtained by the light amount calculation at the time of pre-emission. Is done.
(Light emission amount) = (Original light emission amount) + (Light emission amount corresponding to the corrected shutter speed control value)
Further, the final photographing sensitivity value is calculated again to maintain the original exposure even if the exposure time is changed, and is obtained using the final shutter speed control value, the aperture control value, and the Bv value. . Specifically, the amount of exposure that is overexposed by changing the exposure time relative to the exposure when the exposure time is not changed is adjusted by lowering the photographing sensitivity. Here, the final shutter speed control value corresponds to the actual photographing shutter speed in consideration of the corrected shutter speed control value obtained by the above calculation. (Final shooting sensitivity value) = (Final shutter speed control value) + (Aperture control value)-(Bv value)
If the exposure sensitivity set when the exposure time is not changed is low, the exposure sensitivity may not be lowered by the amount of overexposure due to the change of the exposure time. Therefore, if the exposure sensitivity set when the exposure time is not changed is less than a predetermined value, the exposure sensitivity may not be changed. When the photographing sensitivity is not changed, the photographed image is overexposed, so it is desirable to calculate the light emission amount so as not to overexpose. For example, by reducing the light emission amount by the amount of natural light corresponding to the exposure time that becomes longer due to correction, it is not possible to maintain the light amount ratio of the original strobe light and natural light obtained by the light emission amount calculation at the time of pre-emission, The captured image can be prevented from being overexposed.

  Further, the amount of overexposure due to the change of the exposure time may be adjusted by changing the aperture value instead of adjusting the photographing sensitivity. For example, as the aperture value is increased (the aperture is reduced), the amount of light decreases. Therefore, the aperture value may be increased by an amount corresponding to overexposure. Alternatively, the amount of overexposure may be adjusted by changing both the photographing sensitivity and the aperture value. In that case, as described above, when the exposure sensitivity set when the exposure time is not changed, the aperture value is changed and adjusted when the exposure sensitivity is less than the predetermined value. The sensitivity may be changed and adjusted. As with the shooting sensitivity, if the aperture value is set when the exposure time is not changed, the aperture value is increased by the amount of overexposure by changing the exposure time. There are things you can't do. Therefore, if the aperture value set when the exposure time has not been changed is less than the predetermined value, the aperture value is changed and adjusted. If the aperture value is greater than the predetermined value, the shooting sensitivity is changed and adjusted. You may make it do. In addition, a limit value that can be changed is set for each of the shooting sensitivity and aperture value, and the exposure sensitivity and aperture are set to the extent that the exposure time is changed so that each does not exceed the limit value. You may make it adjust by changing at least one of the values. That is, the shooting sensitivity and the aperture value are set so that the exposure of the image to be shot is equal in each of the case where the exposure time is prolonged due to communication failure and the case where communication is normally performed without communication failure. What is necessary is just to change at least one of these.

  As described above, according to the embodiment of the present invention, the exposure start timing is the same regardless of the occurrence of communication failure, the light quantity ratio between the strobe light and the natural light is the same, and the exposure is appropriately controlled. Can do. Therefore, even when a communication failure occurs, a captured image originally intended by the user can be obtained.

  In the present embodiment, the master device and the slave device are described on a one-to-one basis. However, even when there are a plurality of slave devices, the master device basically communicates with each slave device on a one-to-one basis, so both are limited to one-to-one and one-to-many. Needless to say, the basic control itself can be realized.

  Of course, when there are a plurality of slave devices, it goes without saying that the waiting for Ack at the master device changes from one to all of the devices.

  In addition, the case where wireless communication with a slave device is performed using the wireless communication function provided in the camera body 100 has been described. For example, when the camera body 100 does not have a wireless communication function, the camera body 100 is detachably attached to the camera body. Wireless communication may be performed using the wireless communication function of the external strobe. Alternatively, a detachable wireless communication device may be attached to the camera body 100 to perform wireless communication with the slave device.

  The camera body 100 and the external strobe 101 are configured to perform wireless communication via the wireless communication circuit (147, 133) and the wireless antenna (140, 185). It may be configured to perform communication. When performing optical communication, a wireless communication circuit and a wireless antenna are not required, and a light emitting unit for transmitting an optical signal used for optical communication and a light receiving unit for receiving to each of the camera body 100 and the external strobe 101. May be provided.

  In the present embodiment, the flash control is performed by wireless communication. However, the present invention can be applied even when performing wired communication in which communication failure is less likely to occur than wireless communication.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is a process of reading the program code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Cases are also included.

  Furthermore, the present invention includes a case where the functions of the above-described embodiment are realized by the following processing. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

133 Radio antenna 136 Xenon tube (Xe tube)
140 Wireless antenna 147 Wireless communication circuit 155 Shutter control circuit 158 Camera microcomputer 162 Image processing engine 184 Strobe microcomputer 185 Wireless communication circuit

Claims (10)

An imaging device capable of communicating with a strobe device via a communication means,
From transmission of information instructing the start of main flash to the flash device via the communication means until reception completion information indicating that the information instructing the start of main flash has been received from the flash device Measuring means for measuring the response time of
Exposure control means for performing exposure control;
A light emission amount calculating means for calculating the main light emission amount of the strobe device,
Better if the response time is not the less than the predetermined time than is less than the predetermined time, the exposure control means in the direction of the value of reducing the exposure of at least one of the imaging sensitivity and aperture with a longer exposure time The light emission amount calculating means increases the main light emission amount. When the response time is not less than the predetermined time , the exposure control means increases the exposure time as the response time is longer, and the light emission amount calculation means increases the main light emission amount as the response time is longer. The imaging apparatus according to claim 1, wherein the imaging apparatus is characterized. Said exposure control means, so that the exposure of the image to be captured is equal, that the response time is changing at least one of the imaging sensitivity and the aperture value in the case is not lower than the above is less than the predetermined time and the predetermined time The imaging device according to claim 1, wherein: Having photometric means for measuring subject brightness,
The light emission amount calculating means, if the response time is less than the predetermined time, the main light emission amount calculated based on the subject luminance measured by the light measuring means during the preliminary light emission is performed before the emission, the response 4. The imaging device according to claim 1, wherein when the time is not less than the predetermined time , the main light emission amount is calculated based on the subject luminance measured during the preliminary light emission and the response time. 5. . It said exposure control means, the exposure time when the response time is not less than the predetermined time, the length of the difference between the response time and the predetermined time to the exposure time if the response time is less than the predetermined time The imaging apparatus according to claim 1, wherein the time is an added time. The light emission amount calculating means, the light quantity ratio between light and natural light of the flash device in the image which the response time is taken when not less than the predetermined time, the picture is taken when the response time is less than the predetermined time The imaging apparatus according to claim 1, wherein the main light emission amount is calculated so as to be equal to the light amount ratio in an image.   The imaging apparatus according to claim 1, wherein the communication unit is a communication apparatus that is detachably attached to the imaging apparatus.   The imaging device according to claim 1, wherein the communication unit is a stroboscopic device that is detachably attached to the imaging device and is different from the stroboscopic device.   The imaging apparatus according to claim 1, wherein the communication unit performs wireless communication. A camera system including an imaging device and a strobe device,
Communication means for performing communication between the imaging device and the strobe device;
Reception completion information indicating that the imaging device has received information instructing the start of main light emission after transmitting information instructing the start of main light emission to the strobe device via the communication means. A measuring means for measuring the response time until reception from the device;
Exposure control means for performing exposure control;
A light emission amount calculating means for calculating the main light emission amount of the strobe device,
Better if the response time is not the less than the predetermined time than is less than the predetermined time, the exposure control means in the direction of the value of reducing the exposure of at least one of the imaging sensitivity and aperture with a longer exposure time The light emission amount calculating means increases the main light emission amount.