JP2012003188A - Camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera system capable of enhancing accuracy by correcting an influence on external light control by a beam of light which is emitted from a flash device and reflected by the surface of a barrel of an interchangeable lens and enters an external light control receiver.SOLUTION: A camera system includes an interchangeable lens detachably mounted on a camera body which utilizes a flash device. The interchangeable lens includes means for outputting information of the lens to the camera, and means for detecting distance information. The flash device comprises: a light emitting section; a light control element that detects quantity of light reflected by an object; light emission termination means that terminates the light emission when the quantity of light detected by the light control element reaches a light emission termination level; and correction means for detecting an event that the reflectivity of the lens barrel is large according to the lens information and that the distance to the object is large according to the distance information, and correcting light emission termination level to prevent an under exposure.

Description

  The present invention relates to a camera system that can use a flash device having a light control function and an interchangeable lens.

  In general, there is a camera system that can use a flash device having a dimming function as an interchangeable lens type camera in an imaging apparatus. As a method for controlling the flash emission used in such a camera system, there are an external dimming auto method and a TTL method.

  In this external light control auto method, the light control element, which is the light receiving sensor, receives the reflected light from the flash light emission subject of the flash device, integrates the amount of light received, stops the light emission when it reaches a predetermined level, and the appropriate light emission This is a method for controlling the light quantity.

  In the conventional flash device, the first light emission control means for controlling the light emission by a predetermined guide number (full light emission) and the second light emission control means for controlling the flash light emission by the external dimming auto method. Some have one control means. In the flash device having these two control means, it has been proposed to use the second light emission control means during bounce (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 3-42644

  However, in the flash device as described above, even if the external dimming auto method is used, the direct light from the light emitting unit panel may be reflected by the surface of the lens barrel of the interchangeable lens and enter the external dimming light receiving unit. is there. In such a case, when the reflectance of the surface of the lens barrel of the interchangeable lens is high, there is a problem that the amount of light reflected by this surface and incident on the external light control light receiving portion becomes large, resulting in underexposure.

  An object of the present invention is to improve the light emission accuracy of the flash device by correcting the influence of the light emitted from the flash device on the surface of the lens barrel of the interchangeable lens and entering the external light control light receiving portion and affecting the external light control. is there.

  In order to achieve the above object, a camera system according to the present invention is a camera system in which an interchangeable lens is detachably attached to a camera body that can use a flash device. The flash device includes a light emitting unit, a light control element for detecting the amount of light reflected from the subject, and the light amount detected by the light control element is a light emission stop level. When it is detected that the reflectance of the lens barrel is large based on the lens information, and the distance to the subject is a long distance based on the distance information Correction means for correcting the light emission stop level so as not to cause underexposure.

  According to the present invention, the flash device can emit light with high accuracy regardless of the type of interchangeable lens mounted.

It is a block diagram which shows schematic structure of the camera system concerning 1st Embodiment of this invention. It is a flowchart which shows the process for imaging | photography of the camera system concerning 1st Embodiment of this invention. It is a flowchart which shows the process of the release operation | movement of the camera system concerning 1st Embodiment of this invention. It is a flowchart which shows the strobe control processing of the camera system concerning 1st Embodiment of this invention. (A) (b) is a schematic explanatory drawing which shows the comparative example for demonstrating the effect of the camera system concerning 1st Embodiment of this invention. It is a graph which shows the comparative example for demonstrating the effect of the camera system concerning 1st Embodiment of this invention. It is a graph which illustrates the effect of the camera system concerning a 1st embodiment of the present invention. It is a block diagram which shows schematic structure of the camera system concerning 2nd Embodiment of this invention. It is a flowchart which shows the strobe control processing of the camera system concerning 2nd Embodiment of this invention. 6 is a table used to obtain a reference voltage correction amount used in strobe control processing of the camera system according to the first embodiment of the present invention.

[First embodiment]
Hereinafter, a camera system according to a first embodiment of an imaging apparatus of the present invention will be described with reference to the drawings. In this camera system, an interchangeable lens 200 is detachably attached to a camera body (digital camera body) 100 that can use a flash device (hereinafter referred to as a strobe device) 300.

  In FIG. 1, which is a block diagram showing the configuration of this camera system, 100 is a camera body (digital camera body), 200 is an interchangeable lens, and 300 is a strobe device (flash device). The interchangeable lens 200 and the flash device 300 are detachably attached to the camera body 100, respectively.

  First, the configuration in the camera body 100 (the body of the digital camera) will be described.

  The camera body 100 is configured to be controlled by a CCPU (hereinafter referred to as camera microcomputer) 101 which is a microcomputer.

  This camera microcomputer 101 has a one-chip IC circuit configuration with a built-in microcomputer. This IC circuit configuration includes a CPU, ROM, RAM, input / output control circuit (I / O control circuit), multiplexer, timer circuit, EEPROM (ROM capable of electrically erasing and writing data), A / D, D / A Includes converters. The camera microcomputer 101 is configured to be able to control the camera system by software, and performs various condition determinations.

  The camera body 100 includes an image sensor 102 such as a CCD or CMOS including an infrared cut filter, a low-pass filter, and the like. An image of a subject is formed on the image sensor 102 at the time of photographing by a lens group 202 described later. Further, a shutter 103 is installed that shields the image sensor 102 when not photographing and opens the light when photographing and guides light to the image sensor 102. In addition, a main mirror 104 (half mirror) that reflects a part of light incident from the lens group 202 and forms an image on the focus plate 105 when not photographing is provided. The focus plate 105 is configured so that the focus in an optical finder (not shown) can be visually confirmed. These are the imaging systems included in the camera body 100.

  Reference numeral 106 denotes a photometric circuit configured to divide a photographing range of a subject into a plurality of areas and perform photometry in each area by a photometric sensor mounted in the circuit. The photometric sensor in the photometric circuit 106 is configured to measure the subject image formed on the focus plate 105 via a pentaprism 114 described later. Reference numeral 107 denotes a focus detection circuit, which is configured such that the distance measuring sensor in the circuit has a plurality of points as distance measuring points, and the distance measuring points are included at positions corresponding to the divided portions of the photometric sensor. Yes.

  Reference numeral 108 denotes a gain switching circuit for switching the gain of signal amplification of the image sensor 102. The gain switching by the gain switching circuit 108 is performed according to a command from the camera microcomputer 101 according to shooting conditions, a photographer's input, and the like. Reference numeral 109 denotes an A / D converter that converts the amplified analog signal from the image sensor 102 into a digital signal. Reference numeral 110 denotes a timing generator (TG) for synchronizing the amplified signal input of the image sensor 102 and the conversion timing of the A / D converter 109. A digital signal processing circuit 111 performs image processing on image data converted into a digital signal by the A / D converter 109 according to parameters. Although not shown, the camera body 100 is provided with a memory for storing processed images.

  The camera body 100 is configured to exchange data and transmit commands between the interchangeable lens 200 and the strobe device 300 via the interface signal line SC, for example, using the camera microcomputer 101 as a host. Yes.

  The camera body 100 is configured such that the camera microcomputer 101 performs communication such as transmission of a light emission start signal with the flash microcomputer 310 via the interface signal line SC and a communication clock terminal.

  Furthermore, the camera microcomputer 101 of the camera body 100 is configured to communicate with the lens microcomputer 201 via the interface signal line SC and a terminal for transmitting data.

  Reference numeral 112 denotes various input units provided with switches, buttons, and the like that allow an input operation for gain setting of the image sensor 102 and various camera settings to be input from the outside. A display unit 113 includes a liquid crystal device, a light emitting element, and the like that display various set modes and other shooting information.

  A pentaprism 114 guides the subject image on the focusing screen 105 to a photometric sensor in the photometric circuit 106 and an optical viewfinder (not shown). Reference numeral 115 denotes a sub-mirror that guides the light beam incident from the lens group 202 and transmitted through the main mirror 104 to the distance measuring sensor of the focus detection circuit 107.

  Next, the configuration and operation within the interchangeable lens 200 in this camera system will be described.

  The interchangeable lens 200 includes a microcomputer LPU (hereinafter referred to as a lens microcomputer) 201 that controls the operation of each part of the interchangeable lens 200.

  This lens microcomputer 201 has a microcomputer built-in one-chip IC circuit configuration. IC circuit configuration includes CPU, ROM, RAM, input / output control circuit (I / O control circuit), multiplexer, timer circuit, EEPROM (ROM capable of electrically erasing / writing data), A / D, D / A converter Etc. The lens microcomputer 201 can control the camera system by software. The lens microcomputer 201 determines various conditions, and stores lens type information (ID) and reflectance information of the lens barrel in the ROM or EEPROM of the storage device. Store in advance.

  A lens group 202 includes a plurality of lenses. Reference numeral 203 denotes a lens driving unit that moves an optical system for adjusting the focal position of the lens group 202. In the interchangeable lens 200, the camera microcomputer 101 calculates and controls the driving amount of the lens group 202 based on the output of the focus detection circuit 107 in the camera body 100.

  Reference numeral 204 denotes an encoder 204 that detects a position when the lens group 202 is driven, and detects subject distance information based on encoder information that is an output of the encoder 204.

  The camera microcomputer 101 communicates the calculated driving amount of the lens group 202 to the lens microcomputer 201, operates the lens driving unit 203 by the driving amount according to the driving information of the encoder 204, and moves the lens group 202 to the in-focus position. Let

  Reference numeral 205 denotes an aperture controlled by the lens microcomputer 201 via the aperture control circuit 206.

  The interchangeable lens 200 may have a single focal length or a variable focal length such as a zoom lens.

  In the camera system including the interchangeable lens 200 configured as described above, the camera microcomputer 101 communicates with the lens microcomputer 201, and subject distance information, lens type (type) information (ID information), and lens barrel reflectance Get information.

  Next, the configuration of the strobe device 300 in this camera system will be described.

  The strobe device 300 includes a microcomputer FPU (hereinafter referred to as a strobe microcomputer) 310 that controls the operation of each part of the strobe device 300.

  The strobe microcomputer 310 has a one-chip IC circuit configuration with a built-in microcomputer. This IC circuit configuration includes a CPU, ROM, RAM, input / output control circuit (I / O control circuit), multiplexer, timer circuit, EEPROM (ROM capable of electrically erasing and writing data), A / D, D / A Includes converters. The stroboscopic microcomputer 310 can control the camera system by software, and performs various condition determinations.

  Reference numeral 301 denotes a battery as a power source (VBAT) of the strobe. Reference numeral 302 denotes a booster circuit that boosts the voltage of the battery 301 for storing energy for light emission in a main capacitor (not shown) to several hundred volts. A main capacitor (not shown) is included in the booster circuit 302. The voltage charged in the main capacitor is divided by a voltage detection circuit (not shown), and the divided voltage is input to the A / D conversion terminal of the strobe microcomputer 310.

  Energy charged in a main capacitor (not shown) is applied from the trigger circuit 306 to the discharge tube 307 and excited by a pulse voltage of several KV to emit light, and the subject is irradiated with the light.

  A light emission control circuit 308 controls the start of light emission of the discharge tube 307 together with the trigger circuit 306 and further controls the stop of light emission.

  Reference numeral 322 denotes a photodiode as a light receiving sensor, which is configured as a light control element that receives light of a subject directly or through a glass fiber or the like.

  Reference numeral 309 denotes an integration circuit that integrates the light reception current of the photodiode 322, and the output of the integration circuit 309 is input to the inverting input terminal of the comparator 312 and the A / D converter terminal of the strobe microcomputer (voltage setting means) 310. The non-inverting input terminal of the comparator 312 is connected to the D / A converter output terminal in the flash microcomputer 310, and the output of the comparator 312 is connected to the input terminal of the AND gate 311.

  This D / A converter terminal voltage is a reference voltage for stopping light emission, and can be varied by the flash microcomputer 310. This camera system is configured to change the voltage value according to the surface reflectance of the lens barrel.

  In this camera system, since the reflectance of the lens barrel is large and the lens barrel is underexposed at a long distance, a correction amount (minus) is added from the reference level and the light emission stop level is lowered. Further, in this camera system, the reference level is set when the reflectance of the lens barrel is small and the distance is short.

  The other input terminal of the AND gate 311 described above is connected to the light emission control terminal of the flash microcomputer 310, and the output of the AND gate 311 is input to the light emission control circuit 308.

  The strobe device 300 includes a zoom optical system that changes the irradiation angle of flash light including a reflector 315 and a panel 316. By changing the distance between the reflector 315 and the zoom optical system 316 to a predetermined position, the irradiation guide number and light distribution to the subject are changed.

  Reference numeral 313 denotes a zoom drive unit that moves a zoom optical system 316 including a motor or the like. The drive amount of the zoom optical system 316 is controlled by receiving a signal from the zoom control terminal of the flash microcomputer 310. The zoom drive amount is determined by the focal length information being transmitted from the lens microcomputer 201 to the flash microcomputer 310 via the camera microcomputer 101, and the flash microcomputer 310 calculates the zoom drive amount according to the focal length information.

  Reference numeral 314 denotes a position detection unit such as an encoder that detects the zoom position of the zoom optical system 316, and the position detection unit 314 gives movement information to the position signal terminal of the flash microcomputer 310. Based on this movement information, the stroboscopic microcomputer 310 controls the movement of the zoom optical system 316 by operating the motor in the zoom drive unit 313 by the required drive amount.

  Reference numeral 320 denotes various input units (input interfaces), which are configured with switches disposed on the side surface of the strobe device 300, for example, and configured to allow zoom information to be input by a user operation.

  The strobe device 300 further includes a display unit 321 that displays each state of the strobe device 300 and a light emitting unit 350 that can bounce.

  Next, a specific operation of the camera microcomputer 101 relating to the sequence of the camera system will be described with reference to the flowcharts of FIGS.

  In this camera body 100, when a power switch (not shown) is turned on, the camera microcomputer 101 can operate, and the camera microcomputer 101 starts a predetermined operation from step S1 in the photographing process shown in FIG.

  First, in step S1, the camera microcomputer 101 initializes its own memory and port. Furthermore, the camera microcomputer 101 detects the state of the switch of the input unit 112 and reads an input command or preset input information, and sets various shooting modes such as how to determine the shutter speed and how to determine the aperture. .

  Next, the camera microcomputer 101 determines whether SW1, which is a half-pressed state of a shutter button (not shown), is ON (step S2). The camera microcomputer 101 repeats this step when it is OFF (OFF at Step S2), and proceeds to Step S3 when it is ON (ON at Step S2).

  Next, the camera microcomputer 101 communicates with the lens microcomputer 201 in the interchangeable lens 200 via the communication line SC (step S3). Then, the focal length information of the interchangeable lens 200 (hereinafter referred to as the focal length information of the lens) and the optical information necessary for distance measurement and photometry are acquired. Further, the camera microcomputer 101 communicates with the lens microcomputer 201 in the same manner to acquire lens type information (ID) and lens barrel reflectance information.

  Next, the camera microcomputer 101 checks whether or not the strobe device 300 is attached to the camera body 100. If the strobe device 300 is attached to the camera body 100 (YES in step S4), the process proceeds to step S5, and if not (NO in step S4), the process proceeds to step S6.

  When the strobe device 300 is attached, the camera microcomputer 101 communicates with the strobe microcomputer 310 via the communication line SC, and outputs the focal length information of the lens acquired in step S3 described above to the strobe microcomputer 310 ( Step S5). Accordingly, the flash microcomputer 310 drives the motor drive circuit 313 based on the received focal length information, detects the position by the encoder 314, and controls the irradiation angle of the flash.

  Next, the camera microcomputer 101 determines whether or not the camera is in a mode (AF mode) in which the camera performs an automatic focus detection operation among the shooting modes of the camera set in step S1 (step S6). If the camera microcomputer 101 determines that the AF mode is selected (YES in step S6), the process proceeds to step S7. If the camera microcomputer 101 determines that the AF mode is not selected (NO in step S6), the process proceeds to step S10.

  In step S7, the camera microcomputer 101 drives the focus detection circuit 107 to perform a focus detection operation by a known phase difference detection method. At this time, the camera microcomputer 101 determines which point (ranging point) to match from a plurality of distance measuring points in accordance with the point input and set by the input unit 112 or the shooting mode of the camera. Further, the camera microcomputer 101 may determine a distance measuring point by a known automatic selection algorithm based on the basic concept of near point priority. The distance measuring point determined in step S7 is stored in a RAM (random access memory) (not shown) in the camera microcomputer 101.

  Next, the camera microcomputer 101 calculates a lens driving amount based on information from the focus detection circuit 107. Then, the camera microcomputer 101 transmits the calculated driving amount to the lens microcomputer 201 in the interchangeable lens 200 via the communication line SC. The lens microcomputer 201 that has received the calculation result of the camera microcomputer 101 controls the lens driving circuit 203 based on the calculation result to drive the lens group 202 to the in-focus position (step S8).

  Next, the camera microcomputer 101 communicates with the lens microcomputer 201 in the interchangeable lens 200 via the communication line SC to acquire subject distance information (step S9).

Next, for example, the camera microcomputer 101 divides the screen into six areas and obtains the subject luminance value from the photometric circuit 106.
Its luminance value is
EVb (i) (i = 0 to 5)
Is stored in the RAM (step S10).

  Next, the camera microcomputer 101 performs gain setting processing input from the input unit 112 by the gain switching circuit 108 (step S11). Here, ISO sensitivity is set.

  Next, the camera microcomputer 101 communicates with the flash microcomputer 310 via the communication line SC, and outputs gain setting information acquired by the gain switching circuit 108 to the flash microcomputer 310.

  Next, the camera microcomputer 101 determines an exposure value (EVs) from the subject luminance values EVb of a plurality of areas using a known algorithm (step S12).

  Next, the camera microcomputer 101 checks whether or not the flash microcomputer 310 has output a charging completion signal (step S13). Here, when the camera microcomputer 101 determines that the flash microcomputer 310 is outputting the charge completion signal (YES in step S13), the camera microcomputer 101 proceeds to step S14, and determines that it is not output (NO in step S13). ) Go to Step S15. The camera microcomputer 101 stores the determination result of whether or not the strobe microcomputer 310 outputs a charge completion signal in step S13 for use in a later step.

  Next, the camera microcomputer 101 determines a shutter speed (Tv) and an aperture value (Av) suitable for performing flash photography based on the photometric output obtained in step S10 (step S14).

  Next, the camera microcomputer 101 determines a shutter speed (Tv) and an aperture value (Av) suitable for performing natural light photography (photographing without causing the flash device 300 to emit light) based on the photometric output obtained in step S10. To decide. When the process of step S14 or step S15 is executed, the process proceeds to step S16 in any case.

  Next, the camera microcomputer 101 communicates with the strobe microcomputer 310 via the communication line SC, and outputs information about other strobes to the strobe microcomputer 310 (step S16).

  Next, the camera microcomputer 101 determines whether SW2, which is a shooting start switch (not shown), is ON. If it is determined to be OFF, the operation from step S1 to step S16 is repeated. If the camera microcomputer 101 determines that the camera is ON, the camera microcomputer 101 starts a series of release operation processes shown in the flowchart of FIG.

  Next, the release operation process will be described with reference to the flowchart of FIG.

  When the processing of the release operation is started, the camera microcomputer 101 raises the main mirror 104 prior to the exposure operation and moves it away from the photographing optical path (step S18).

  Next, the camera microcomputer 101 transmits strobe information to the strobe device 300 to the strobe microcomputer 310 via the SC line (step S19).

  Next, the camera microcomputer 101 issues a command to the lens microcomputer 201 to obtain an aperture value (AV) based on the determined exposure value (EVs). At the same time, the camera microcomputer 101 controls the shutter 103 via a shutter control circuit (not shown) so that the determined shutter speed value (TV) is obtained (step S20).

  Next, the camera microcomputer 101 gives a light emission signal to the flash microcomputer 310 via the SC line in synchronization with the fully opening of the shutter 103. At the same time, the flash microcomputer 310 performs main light emission control so as to obtain an appropriate light emission amount (step S21). A detailed description of the strobe light emission will be given later.

  Next, when the above-described series of exposure operations is completed, the camera microcomputer 101 lowers the main mirror 104 that has been retracted from the photographing optical path and sets it again in the oblique manner in the photographing optical path (step S22).

  Next, the camera microcomputer 101 generates a signal obtained by amplifying the pixel data of the image sensor 102 with the gain set by the gain switching circuit 108, and converts the amplified signal as a digital signal by the A / D converter 109. The pixel data thus converted is subjected to predetermined signal processing such as white balance in the signal processing circuit 111 (step S23).

  Next, the camera microcomputer 101 stores the image data processed as described above in a memory (not shown) (step S24) and ends the shooting routine.

  Next, a specific operation (strobe control processing) in the strobe microcomputer 310 in the strobe device 300 will be described with reference to the flowchart of FIG.

  In the strobe device 300, when a power switch (not shown) is turned on, the strobe microcomputer 310 can operate, and the strobe microcomputer 310 starts a predetermined operation from step S101 in FIG.

  First, in step S101, the flash microcomputer 310 initializes its own memory and port. Further, the flash microcomputer 310 detects the state of the input switch, reads the input command and preset input information, and sets the flash shooting mode, the light emission amount, and the like.

  Next, the flash microcomputer 310 receives flash information from the camera microcomputer 101 via the communication line SC. Then, the flash microcomputer 310 stores the flash information in a RAM (random access memory) (not shown) in the flash microcomputer 310.

  Next, the flash microcomputer 310 starts the operation of the booster circuit 302 and prepares for light emission (step S102).

  Next, the flash microcomputer 310 checks the focal length information of the lens received from the camera microcomputer 101 via the communication line SC. Then, the flash microcomputer 310 stores (stores) the focal length information of the lens received from the camera microcomputer 101 in its own memory. If the focal length information of the lens has been stored in its own memory before this, the stored content is updated (step S103).

  Next, the flash microcomputer 310 displays the focal length information of the lens stored in its own memory on the display unit 321 (step S104).

  Next, the stroboscopic microcomputer 310 gives movement information to the position signal terminal of the stroboscopic microcomputer 310 via the encoder 314 so that the illuminating angle of the stroboscopic light becomes the position of the irradiating angle selected in step S104. The stroboscopic microcomputer 310 operates the motor in the zoom driving unit 313 by a necessary driving amount by the position signal terminal, and operates to a predetermined position by the position signal of the encoder 314 (step S105).

  Next, the flash microcomputer 310 acquires lens type information (ID), lens barrel reflectance information, and distance information transmitted from the camera microcomputer 101 (step S106).

  Next, the stroboscopic microcomputer 310 corrects the correction level of the external dimming according to the focused distance information based on the lens type information (ID) and the reflectance information of the lens barrel. That is, the stroboscopic microcomputer 310 sets a correction method by the processing of step S107 to step S110 from the acquired lens type information (ID), lens barrel reflectance information, and distance information.

  Hereinafter, setting of the correction method will be described with reference to FIGS. 4, 7, and 10. In the correction amount illustrated in FIG. 10, the determination of the lens is four. However, the correction is not limited to this, and the determination may be made in five or more cases.

  In the strobe device 300, the function of correcting the correction level of the external dimming according to the focused distance information is configured as follows.

  In the strobe device 300, an output signal obtained by receiving the light reflected from the subject by the dimming element 322 and integrating the light by the integrating circuit 309 is input to the inverting input terminal of the comparator 312 and the A / D converter terminal of the strobe microcomputer 310. It has a configuration.

  A non-inverting input terminal of the comparator 312 is connected to a D / A converter output terminal in the flash microcomputer 310. The output terminal of the comparator 312 is connected to the input terminal of the AND gate 311.

  The signal output from the AND gate 311 is input to the light emission control circuit 308. When receiving the signal from the AND gate 311, the light emission control circuit 308 stops the light emission.

  Here, the D / A converter terminal voltage in the flash microcomputer 310 is a reference voltage (VTH) for stopping light emission. This reference voltage (VTH) is configured to be variable by the stroboscopic microcomputer 310 and is obtained by the following equation.

Reference voltage (VTH) = VTH0 + k + L
here,
VTH0: reference voltage when there is no influence of the reflectance of the lens barrel k: a correction amount L based on the reflectance of the lens barrel L: a correction amount k + L based on the subject distance.

  Specifically, the external dimming correction is performed by adding a correction amount (minus) from the reference level to reduce the light emission stop level because the lens barrel has a large reflectance and is underexposed at a long distance because it is underexposed. (Increase light emission). In this external dimming correction, the reflectance of the lens barrel is small, and the reference level is used in the case of a short distance.

  In order to perform the above-described external dimming correction, in step S107 in the flowchart of FIG. 4, when the flash microcomputer 310 determines that the lens type information (ID) is “001” (YES in step S107), Proceed to step S111.

  Next, the flash microcomputer 310 determines the correction amount L based on the subject distance using the lens distance information (step S111). Then, the flash microcomputer 310 refers to the table shown in FIG. 10 to obtain the reference voltage correction amount “k1” corresponding to the lens barrel reflectance information whose lens type information (ID) is “001”. The stroboscopic microcomputer 310 sets the reference voltage VTH1 based on the reference voltage correction amount “k1” (step S112), and proceeds to the next step S117.

  If the flash microcomputer 310 determines that the lens type information (ID) is not “001” (NO in step S107), the flash microcomputer 310 proceeds to step S108.

  Next, when the flash microcomputer 310 determines that the lens type information (ID) is “002” (YES in step S108), the flash microcomputer 310 proceeds to step S113.

  Next, the flash microcomputer 310 determines the correction amount L based on the subject distance using the lens distance information (step S113). Then, the flash microcomputer 310 obtains the reference voltage correction amount “k2” corresponding to the lens barrel reflectance information whose lens type information (ID) is “002” with reference to the table shown in FIG. Then, the flash microcomputer 310 sets the reference voltage VTH2 based on the reference voltage correction amount “k2” (step S114), and proceeds to the next step S117.

  If the flash microcomputer 310 determines that the lens type information (ID) is not “002” (NO in step S108), the flash microcomputer 310 proceeds to step S109.

  Next, when it is determined that the lens type information (ID) is “003” (YES in step S109), the flash microcomputer 310 proceeds to step S115.

  Next, the flash microcomputer 310 uses the lens distance information to determine a correction amount L based on the subject distance (step S115). Then, the flash microcomputer 310 refers to the table shown in FIG. 10 to obtain the reference voltage correction amount “k3” corresponding to the lens barrel reflectance information whose lens type information (ID) is “003”. Then, the flash microcomputer 310 sets the reference voltage VTH3 based on the reference voltage correction amount “k3” (step S112), and proceeds to the next step S117.

  If the flash microcomputer 310 determines that the lens type information (ID) is not “003” (NO in step S109), the flash microcomputer 310 proceeds to step S110. In this case, since the stroboscopic microcomputer 310 determines that there is almost no lens barrel reflectance, the stroboscopic microcomputer 310 sets the reference voltage VTH0 (step S110), and proceeds to the next step S117.

In addition, the reference voltage mentioned above has the relationship of the following formula.
[Formula 1]
VTH0>VTH1>VTH2> VTH3
Further, by correcting as described above, as shown in FIG. 7, before the correction, the light emission amount is under as shown by the curve B, but the reference data is corrected corresponding to the subject distance. Thus, it can be corrected to an appropriate range like the curve of A ′. Here, the correction is made with reference to the table, but the same result can be obtained even if calculation is performed.

  Next, the stroboscopic microcomputer 310 determines whether or not the voltage boosted by the booster circuit 302 has reached a voltage level necessary for light emission of the discharge tube 307 (whether charging is complete) (step S117).

  If the stroboscopic microcomputer 310 determines that the voltage boosted by the booster circuit 302 has not reached the voltage level necessary for the light emission of the discharge tube 307, the process proceeds to step S123.

  Next, the flash microcomputer 310 outputs a charge incomplete signal to transmit that the flash is not ready to emit light to the camera microcomputer 101 via the communication line SC, and transmits a charge signal to the booster circuit 302 (step S123). . Thereafter, the flash microcomputer 310 returns to step S102 and repeats the above-described steps.

  If the flash microcomputer 310 determines that the voltage level necessary for the light emission of the discharge tube 307 has been reached, the process proceeds to step S118.

  Next, the flash microcomputer 310 outputs a charge completion signal and transmits that the flash is ready to emit light to the camera microcomputer 101 via the communication line SC.

  Next, the flash microcomputer 310 determines whether or not the light emission start signal is output from the camera microcomputer 101. If it is determined that the light emission start signal is not output (NO in step S119), the process returns to step S102. Repeat the above steps.

  On the other hand, when it is determined that the light emission start signal is output (YES in step S119), the flash microcomputer 310 proceeds to step S120. Then, the strobe microcomputer 310 gives a trigger signal to the light emission control circuit 308 via the AND gate 311 from the light emission control terminal of the trigger circuit 306 and the strobe microcomputer 310 to start the light emission of the strobe (step S120).

  Next, when the flash microcomputer 310 receives the reflected light from the subject with the photodiode 322, the integration circuit 309 integrates the light reception current of the photodiode 322. The output integrated by the integration circuit 309 is input to the inverting input terminal of the comparator 312 and the A / D converter terminal of the strobe microcomputer 310. At this time, the non-inverting input of the comparator 312 is connected to the D / A converter output terminal in the flash microcomputer 310, and as described above, the reference is a D / A converter value corresponding to the light emission amount corresponding to the appropriate light amount. The voltage VTH is set.

  Next, the flash microcomputer 310 continues to emit light until it reaches the set reference voltage VTH level (NO in step S121), and when it reaches the reference voltage VTH level (YES in step S121), it proceeds to step S122. Proceed to

  Next, the flash microcomputer 310 outputs a light emission stop signal from the AND gate 311 and stops the light emission by the light emission control circuit 308, returns to step S102, and repeats the above steps.

  Next, a comparative example for understanding the effects of the camera system according to the present embodiment will be described with reference to FIGS.

  FIG. 5 is a schematic explanatory diagram when a subject is photographed by the camera system of the present embodiment, 500 is a subject to be photographed, 100 is a camera body, 200 is an interchangeable lens, 300 is a strobe device (flash device), and 350 is a light emitting unit. Reference numeral 322 denotes a photodiode which is a light control element.

  As for the interchangeable lens 200 used in such a camera system, there is a lens barrel whose surface color is different and reflectance is different depending on a difference in focal length of the lens or a use.

  As shown in FIG. 5A, the light (L 1) emitted from the light emitting unit 350 is reflected by the subject 500 (L 2) and received by the dimmer 322. At this time, a part of the light from the light emitting unit 350 is reflected by the interchangeable lens 200 as direct light (L3), and a part of the reflected light (L4) is received by the light control element.

  Here, when the reflectance of the lens barrel is small and the distance is short, “reflected light from the subject (L2)> reflected light of the lens barrel (L4)”, and thus dimming is performed appropriately.

  However, as shown in FIG. 5B, when the subject is at a long distance, the light (L1 ′) emitted from the light emitting unit 350 is reflected by the subject 500 (L2 ′) and received by the light control element 322. . At this time, part of the light from the light emitting unit 350 is reflected by the interchangeable lens 200 as direct light (L3 ′), and the reflected light (L4 ′) is received by the light control element.

  In such a case where the reflectance of the lens barrel is large and the distance is long, the relationship of “reflected light from the subject (L2 ′) <lens barrel reflected light (L4 ′)” is satisfied. It will be under.

  The state at this time will be described with reference to the graph of FIG. In the graph of FIG. 6, the horizontal axis indicates the subject distance, and the vertical axis indicates the step with respect to the appropriate light amount. 6A shows the accuracy when the reflectance of the lens barrel is low. FIG. 6B shows the accuracy of the light emission amount when the reflectance of the lens barrel is high (for example, the color of the lens barrel is white). In the case of A, the accuracy of the light emission amount is almost constant regardless of the subject distance, but in the case of B, the accuracy of the light emission amount decreases depending on the subject distance.

  Moreover, the position of (a) of the graph of FIG. 6 corresponds to the case of FIG. 5 (a), and the position of (b) of the graph of FIG. 6 corresponds to the case of FIG.

  From FIG. 6, when the reflectance of the lens barrel is high, the balance between the reflected light from the subject and the reflected light from the lens barrel changes greatly according to the subject distance, and the accuracy of the light emission amount increases as the subject distance increases. It can be seen that it affects.

  Therefore, in the camera system according to the present embodiment, correction of external dimming is performed by adding a correction amount (minus) from the reference level and reducing the light emission stop level when the reflectance of the lens barrel is large and the distance is long. To correct underexposure. In this external dimming correction, the reference level is set when the reflectance of the lens barrel is small and the distance is short. Thereby, in the camera system according to the present embodiment, it is possible to correct external dimming appropriately regardless of the type of interchangeable lens. Furthermore, with this camera system, it is possible to achieve both improvement in the accuracy of light control over long distances and an increase in the degree of freedom of the position of the light control sensor. Can be

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. In the camera system according to the second embodiment, the camera body 100 and the strobe device 300 are connected by an extension cord.

  In the block diagram of FIG. 8, reference numeral 400 denotes an extension cord for connecting the camera and the strobe device, and each communication terminal is constituted by a known detachable connector. Reference numerals 401 and 402 denote interface circuits, which are configured by known buffer circuits and connection recognition circuits.

  In the block diagram of FIG. 8, the components other than those described above are the same as those described in the block diagram of FIG. 1 described above, and therefore the same members are denoted by the same reference numerals and the description thereof is omitted.

  Next, strobe control processing in the camera system according to the second embodiment will be described with reference to the flowchart of FIG. The flowchart of the operation in FIG. 9 corresponds to the flowchart of FIG. 4 described above, and therefore only different parts will be described. To do.

  In this strobe control process, when the power switch of the camera system is input, the strobe microcomputer 310 performs the operations from step S101 to step S105 as described above. The stroboscopic microcomputer 310 operates (step S105) so that the irradiation angle of the stroboscopic light becomes the position of the selected irradiation angle, and then proceeds to step S105-2.

  In step S105-2, the flash microcomputer 310 determines whether the extension cord is connected by using the interface circuits 401 and 402. If the flash microcomputer 310 determines that the camera is an off-camera with the extension cord connected (YES in step S105-2), the flash microcomputer 310 proceeds to step S110 and determines that the camera is not an off-camera (step S105-). 2), the process proceeds to step S106.

  Next, the flash microcomputer 310 performs the same operation as the above-described step S106 to step S116 in FIG.

  As described above, the camera system according to the second embodiment includes means for detecting that the camera body 100 and the strobe device 300 are connected with a detachable cord. Then, the flash microcomputer 310 performs control so that the light emission stop timing of the light control element is not corrected based on the lens information and the distance information when the cord is connected. As a result, since the strobe device 300 is disposed at a position away from the camera body 100, unnecessary external dimming correction is not performed when there is no influence of the reflected light from the lens barrel. You can

  Note that the configurations, operations, and effects of the second embodiment other than those described above are the same as those of the above-described first embodiment, and thus description thereof is omitted.

[Third Embodiment]
In the camera system according to the third embodiment, the camera body 100 and the flash device 300 are connected by wireless communication.

  In the third embodiment, in step S4 of FIG. 2 described above, the camera microcomputer 101 determines whether or not the strobe device is attached based on the presence or absence of strobe communication. For this reason, the camera microcomputer 101 determines whether or not the strobe is mounted in step S105-2 in the flowchart of FIG. If the camera microcomputer 101 determines that the strobe is not mounted (YES in step S105-2), the camera microcomputer 101 controls to branch to step S110 in the flowchart of FIG. 8 when transmitting strobe data by wireless communication.

  Alternatively, the camera microcomputer 101 determines the presence or absence of the strobe by determining whether or not there is communication with the strobe microcomputer 310. When the camera microcomputer 101 determines that the strobe is not attached, the camera microcomputer 101 controls to branch from step S105-2 to step S110 in the flowchart of FIG.

  As a result, since the strobe device 300 is disposed at a position away from the camera body 100, unnecessary external dimming correction is not performed when there is no influence of the reflected light from the lens barrel. You can

  Note that the configurations, operations, and effects of the third embodiment other than those described above are the same as those of the first embodiment described above, and thus the description thereof is omitted.

101 Camera microcomputer 201 Lens microcomputer 310 Strobe microcomputer

Claims (6)

In a camera system in which an interchangeable lens is detachably attached to a camera body that can use a flash device,
The interchangeable lens comprises means for outputting lens information to the camera, and means for detecting distance information,
The flash device includes a light emitting unit, a light control element that detects a light amount reflected from a subject, and a light emission stop unit that performs an operation of stopping light emission when the light amount detected by the light control element reaches a light emission stop level. The lens information detects that the reflectance of the lens barrel is large, and the distance stop information corrects the light emission stop level so that underexposure does not occur when the distance to the subject is a long distance based on the distance information. Means,
A camera system characterized by that.   The camera system according to claim 1, wherein the lens information is information (ID information) of an interchangeable lens type.   The camera system according to claim 1, wherein the lens information is information on reflectance of a lens barrel of the lens.   2. The camera system according to claim 1, wherein the correction means for correcting the light emission stop level is configured to change the light emission stop level by a voltage setting means that can be varied with a comparator. It further comprises detection means for detecting that the camera body and the flash device are detachably connected with a cord,
2. The camera system according to claim 1, wherein when the detection unit detects that the cord is connected, the correction unit performs control so that the light emission stop level is not corrected. 3. It further comprises detection means for detecting that a flash device is attached to the camera body,
2. The camera system according to claim 1, wherein when the detection unit detects that the flash device is attached, the correction unit performs control so that the light emission stop level is not corrected. 3.

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