JP3647085B2 - Camera system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera system that adjusts the light emission amount of a strobe so that proper exposure can be automatically obtained in a state where the strobe is used.
[0002]
[Prior art]
Various camera systems as described above have been proposed in the past, and in such a camera system, so-called TTL dimming that obtains an appropriate amount of light emission by measuring the film surface reflected light of the light reaching the film surface during exposure is performed. Commonly used. In this TTL light control, as shown in FIG. 9, the reflected light of the subject image formed on the film surface 9 through the main mirror 2 including the photographing lens 32 and the half mirror is reflected by the light control sensor 24 through the image forming lens 23. Measure the light. Then, when the integral amount of the photometric value reaches a predetermined amount, the strobe light emission is stopped and the light emission amount is controlled.
[0003]
[Problems to be solved by the invention]
However, in TTL dimming, the subject is indirectly and gently measured at a specific location on the screen using diffuse reflection light on the film surface, so the exposure is not stable due to the difference in the size and composition of the subject. There is a problem that it is difficult to perform continuous shooting (continuous shooting) with the same exposure.
[0004]
Further, Japanese Patent Application Laid-Open No. 4-331935 proposes a method of correcting the TTL dimming at the time of main light emission by performing pre-light emission before the main light emission of the strobe. For this reason, if the pre-flash is performed with the aperture of the photographic lens in the narrowed state, accurate photometry cannot be performed, and as a result, correct correction cannot be performed or complicated calculations are required. .
[0005]
Further, if the strobe light emitting unit is shifted from the subject after worrying about overexposure after pre-emission, correct correction cannot be made if the photometric value at the time of pre-emission is used as it is.
[0006]
[Means for Solving the Problems]
  thereThe present invention performs accurate photometry at the time of pre-emission, and can stably and properly obtain an exposure regardless of the situation of the subject, the difference in composition and the type of film.It is to provide a camera system.
[0009]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides a camera system for performing photometry by pre-flashing a strobe before the main flash of the strobe.In at least one of the plurality of regionsMore than onceMetering operationAnd the time required for the first photometric operation performed immediately before the pre-flash among the photometric operations performed a plurality of timesTo be the same as the time required for the second photometric operation performed during pre-flash, andFirstAnd secondOther than the metering operationotherShorter than the time required for metering operationIn addition to setting, the light emission amount of the main light emission is determined using the photometric results obtained by the first and second photometric operations.Control means.
  It is desirable that the pre-light emission be performed with the photographing lens aperture open. With this configuration, even when the lens aperture is narrowed down before pre-emission, the pre-emission and photometry are performed after the aperture is once opened to perform accurate photometry. it can.
[0010]
  Also,Detection means for detecting that shooting conditions have been changedProvided,If the detection means detects after the pre-flash but before the main flash, pre-flash is performed again.It is desirable to configure as follows.That is, for example, if the photometry value by the first pre-flash is fixed and then the shooting conditions such as the direction of the strobe and the shooting mode are changed, by performing the pre-flash again and the main flash, Accurate photometry corresponding to the changed shooting conditions and proper main light emission control can be performed.
[0011]
The pre-emission is desirably performed by flat emission that maintains the emission intensity substantially constant.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 is a cross-sectional view mainly illustrating an optical configuration of a strobe control camera system implemented by applying the present invention to a single-lens reflex camera.
[0013]
Reference numeral 1 denotes a camera body in which optical parts, mechanical parts, electric circuits, films, and the like necessary for taking a photograph are stored. Reference numeral 2 denotes a main mirror. The main mirror 2 is obliquely installed in the imaging optical path according to the observation state and the imaging state.QuitOr left. Further, the main mirror 2 is a half mirror, and when it is obliquely arranged in the photographing optical path, approximately half of the light beam from the subject is transmitted through a focus detection optical system described later.
[0014]
Reference numeral 3 denotes a focusing plate disposed on the planned imaging plane of the photographing lenses 12 to 14, and reference numeral 4 denotes a penta roof prism for changing the finder optical path. Reference numeral 5 denotes a finder, and the photographer can observe the photographing screen by observing the focus plate 3 through the finder 5. Reference numerals 6 and 7 denote an imaging lens and a multi-divided photometric sensor for measuring the luminance of the subject in the observation screen, respectively. The imaging lens 6 is separated from the focusing plate 3 via the reflected light path in the penta roof prism 4 and multi-divided. The photometric sensor 7 is related to the conjugate.
[0015]
Here, the function of the multi-segment photometric sensor 7 will be described in detail. FIG. 2 shows a division view of the photometric area on the photographing screen. Reference numeral 40 denotes the entire shooting screen. Reference numeral 41 denotes an area division for photometry on the photographing screen of the multi-division photometric sensor 7, and the photographing screen is divided into six areas like E0, E1, E2, E3, E4, and E5. As described above, the multi-division photometric sensor 7 associated with the imaging screen in a conjugate manner can divide the imaging screen and measure and output each luminance value.
[0016]
In FIG. 1, 8 is a shutter. Reference numeral 9 denotes a photosensitive member, which is formed of a silver salt film or the like. Reference numeral 25 denotes a sub mirror. The sub mirror 25 bends the light beam from the subject downward and guides it toward the focus detection unit 26.
[0017]
In the focus detection unit 26, a secondary imaging mirror 27, a secondary imaging lens 28, a focus detection line sensor 29, and the like are disposed. The secondary imaging mirror 27 and the secondary imaging lens 28 form a focus detection optical system, and this focus detection optical system connects the secondary imaging surface of the photographing optical system onto the focus detection line sensor 29. It is out. The focus detection unit 26 realizes an automatic focus detection device by controlling the focus adjustment mechanism of the photographing lens by detecting the focus state of the subject in the photographing screen by a known phase difference detection method by processing of an electric circuit described later. doing. This automatic focus detection apparatus detects the focus state of three predetermined points in the screen. FIG. 2 shows the positions of the three points. The distance measuring points P0, P1, and P2 are the positions.
[0018]
Reference numeral 10 denotes a mount contact as an interface between a known camera and a lens, and 11 denotes a lens barrel installed on the camera body. Reference numerals 12 to 14 denote photographing lenses. Reference numeral 12 denotes a first group lens. The first group lens 12 is moved to the left and right on the optical axis to adjust the focus position of the photographing screen. Reference numeral 13 denotes a second group lens. The second group lens 13 is movable to the left and right on the optical axis, thereby changing the photographing screen and changing the focal length of the photographing lens. Reference numeral 14 denotes a three-group fixed lens. Reference numeral 15 denotes a photographing lens aperture.
[0019]
Reference numeral 16 denotes a first group lens drive motor, which controls the operation of the motor 16 in accordance with an automatic focus adjustment operation, and can automatically adjust the focus position by moving the first group lens 12 left or right. Reference numeral 17 denotes a lens aperture driving motor. By controlling the operation of the motor 17, the photographing lens aperture can be opened or stopped.
[0020]
Reference numeral 18 denotes an external strobe. The strobe 18 is attached to the camera body 1 and performs light emission control in accordance with a signal from the camera. In addition, the strobe 18 has a function (bounce function) that can change the direction of the light emitting portion irrespective of the optical axis of the photographing lens.
[0021]
Reference numeral 19 denotes a xenon tube, and the xenon tube 19 converts current energy into emission energy. 20 and 21 are a reflector and a Fresnel, respectively.lensThese have the role of efficiently condensing the emitted energy toward the subject. Reference numeral 22 denotes a known accumulator contact that serves as an interface between the camera body 1 and the external strobe 18.
[0022]
Reference numeral 30 denotes a glass fiber. The glass fiber 30 guides light emitted from the xenon tube 19 to a monitor sensor (PD1) 31. The sensor (PD1) 31 directly measures the amount of pre-flash and main flash of the strobe, and is used for controlling the main flash. Reference numeral 32 denotes a sensor (PD2) that monitors light emitted from the xenon tube 19. By the output of the sensor (PD2) 32, the light emission current of the xenon tube 19 can be limited and the strobe can emit flat light. Reference numeral 33 denotes a sensor for detecting the direction of the light emitting portion of the external strobe 18 by the bounce function.
[0023]
In FIG. 1, only the optical mechanical member is shown among the members necessary to realize the present invention, and an electric circuit member is also necessary, but it is omitted here.
[0024]
FIG. 3 shows an electric circuit block diagram of the camera system of the present embodiment. In this figure, the members shown in FIG.
[0025]
The MPU 100 performs a required arithmetic processing operation based on the clock generated by the oscillator 101.
[0026]
The EEPROM 100b stores film counters and other shooting information. The A / D converter 100c A / D converts analog signals from the focus detection circuit 105 and the photometry circuit 106. The MPU 100 sets various states by signal processing the A / D value from the A / D converter 100c.
[0027]
The MPU 100 includes a focus detection circuit 105, a photometry circuit 106, a shutter control circuit 107, a motor control circuit 108, a film travel detection circuit 109, a switch sense circuit 110, andLCD displayA circuit 111 is connected. Further, the MPU 100 transmits a signal to the lens control circuit 112 disposed in the photographing lens via the mount contact 10, and the shoe is connected to the strobe control circuit 102 disposed in the external strobe 18. Signal transmission is performed via the contact 22.
[0028]
The line sensor 29 is a known CCD line sensor including three sets of line sensors Line-L, Line-C, and Line-R corresponding to the three distance measuring points on the finder described above. The focus detection circuit 105 performs accumulation control and readout control of these line sensors 29 in accordance with signals from the MPU 100, and outputs respective pixel information to the MPU 100. The MPU 100 performs A / D conversion on the pixel information and performs focus detection by a known phase difference detection method. Further, the MPU 100 adjusts the focus of the lens by exchanging signals with the lens control circuit 112 based on the focus detection information.
[0029]
The photometry circuit 106 outputs to the MPU 100 the output from the multi-division photometry sensor 7 that divides the screen into six areas as described above as the luminance signal of each area in the screen. The photometry circuit 106 outputs a luminance signal in both 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 MPU 100 performs A / D conversion on the luminance signal, and calculates the aperture value, the shutter speed, and the strobe main light emission amount at the time of exposure for adjusting the exposure of shooting.
[0030]
The shutter control circuit 107 runs the shutter front curtain (MG-1) and the shutter rear curtain (MG-2) according to the signal from the MPU 100, and controls the exposure operation.
[0031]
The motor control circuit 108 controls the motor M in accordance with a signal from the MPU 100, thereby causing the main mirror 2 to be inclined and moved (up / down), charging the shutter, and feeding the film.
[0032]
The film running detection circuit 109 detects whether or not the film has been wound up by one frame when feeding the film, and sends a signal to the MPU 100.
[0033]
SW1 is turned on by a first stroke of a release button (not shown) to start photometry and AF. SW2 is turned on by the second stroke of the release button to start the exposure operation. Signals from SW1, SW2 and other camera operation members (not shown) are detected by the switch sense circuit 110 and sent to the MPU 100.
[0034]
The liquid crystal display circuit 111 controls the display of the in-finder LCD 24 specifically shown in FIG. 2 and the monitor LCD 42 not specifically shown according to a signal from the MPU 100.
[0035]
The lens control circuit 112 communicates with the MPU 100 via the lens mount contact 10 to operate the first lens drive motor 16 and the lens aperture motor 17 to adjust the lens focus and aperture.15Is controlling. Reference numerals 35 and 36 denote a photodetector and a pulse plate, respectively, and the lens control circuit 112 counts the number of pulses of the pulse plate 36 via the photodetector 35, whereby position information of the first group lens can be obtained. The focus can be adjusted. Further, the absolute distance information of the subject is transmitted to the MPU 100 based on the position information of the first lens group.
[0036]
The strobe control circuit 200 is a circuit that emits strobe light toward a subject in accordance with a signal from the MPU 100, and controls the amount of light emission, the intensity of flat light emission, and the light emission time.
[0037]
Reference numeral 201 denotes a DC / DC converter, which can boost the battery voltage in accordance with an instruction from the strobe control circuit 200 and store about 300 V in the main capacitor C1.
[0038]
R1 / R2 is a voltage dividing resistor provided for the strobe control circuit 200 to monitor the voltage of the main capacitor C1. The strobe control circuit 200 indirectly monitors the voltage of the capacitor C1 by A / D converting the divided voltage by the A / D converter 202, stops the DC / DC converter 201, and stops the boosting. The current charging voltage can be monitored and transmitted to the MPU 100.
[0039]
A trigger circuit 203 outputs a trigger via the strobe control circuit 200 in accordance with an instruction from the MPU 100 during exposure. By this trigger, the charge energy stored in the main capacitor C1 is discharged in the xenon tube 19, and strobe light emission is started.
[0040]
Reference numeral 204 denotes a light emission stop circuit. The light emission stop circuit 204 is turned on at the time of the trigger output described above to start light emission of the xenon tube 19 and is turned off by the output of the comparator 205 or the comparator 206 and the signal from the strobe control circuit 200, and the xenon tube 19 is turned off. Stop flashing.
[0041]
Reference numeral 33 denotes a sensor for detecting the direction of the light emitting unit including the xenon tube 19 as described above, and the output of the sensor 33 can be read out via the strobe control circuit 200.
[0042]
Next, the circuit will be described in detail while explaining the operation of the strobe.
[0043]
<About flat light emission>
The strobe control circuit 200 sets a predetermined value in the D / A converter 207. At this time, since the xenon tube 19 has not started to shine, the photocurrent of the monitor sensor 32 (PD2) is small, and the output of the monitor circuit 209 input to the inverting input terminal of the comparator 206 is low. Therefore, the output from the comparator 206 to the light emission stop circuit 204 becomes HI.
[0044]
When the trigger is output and the xenon tube 19 starts to emit light, the light emission intensity immediately increases, the photocurrent of the monitor sensor 32 (PD2) increases, the output of the monitor circuit 209 increases, and the output of the comparator 206 is LOW.
[0045]
When the output of the comparator 206 becomes LOW, the light emission stop circuit 204 works and the discharge loop of the xenon tube 19 is cut off, but a recirculation loop is formed by the diode D1 and the coil L1, and the light emission intensity gradually decreases without instantaneously decreasing. Falling.
[0046]
When the emission intensity decreases, the photocurrent of the monitor sensor 32 (PD2) decreases, so that the output of the comparator 206 turns to HI again, a discharge loop of the xenon tube 19 is formed, and the emission intensity increases. As described above, the flat light emission control is performed in which the light emission intensity repeatedly increases and decreases in a short cycle by the output of the comparator 206, and as a result, the light emission is continued at a substantially constant light emission intensity.
[0047]
The end of the flat light emission is the strobe control circuit 200.FromIs performed by directly outputting a signal to the light emission stop circuit 204.
[0048]
Further, the light emission intensity of flat light emission is obtained by varying the voltage input to the non-inverting input terminal of the comparator 206 in accordance with the digital value given to the D / A converter 207, so that the photocurrent of the monitor sensor 32 (PD2). The operating point is changed and controlled to a desired value. The light emission time is also controlled to a desired time.
[0049]
<About pre-flash and integration>
In pre-emission, the above-described flat emission is performed at a predetermined emission intensity for a predetermined time.
[0050]
At this time, the monitor sensor 31 (PD1) measures the light emission photometric brightness of the xenon tube 19, the strobe control circuit 200 instructs the integration circuit 211 to start integration, and the integration circuit 211 integrates the pre-emission based on the output from the monitor circuit 210. To start. Note that the light emission stop circuit 204 receives the output of the comparator 205 whose output is input to the inverting input terminal, but this is set to be ignored by the signal from the strobe control circuit 200. Therefore, the above-described flat light emission control is not hindered.
[0051]
When the pre-emission for a predetermined time is completed, the strobe control circuit 200 performs A / D conversion on the output of the integration circuit 211 integrating the pre-emission by the A / D converter 202, and reads the integration value as a digital value.
[0052]
<Main flash control>
The MPU 100 obtains an appropriate integral value of the main light emission amount from the integrated value of the pre-light emission described above, the subject reflected light luminance value from the multi-division photometry sensor 7 at the time of the pre-light emission, and the like. The appropriate integral value is set in the A converter 207. Next, the MPU 100 sets the integrating circuit 211 to an initial state, and causes the trigger circuit 203 to start light emission.
[0053]
The light emission luminance of the xenon tube 19 measured by the monitor sensor 31 (PD1) is integrated by the integration circuit 211. When the integral output reaches the set proper integral value, the output of the comparator 205 is switched from HI to LOW, and the light emission is stopped. The circuit 204 stops light emission. At this time, the output of the comparator 206 is set to be ignored by the signal from the strobe control circuit 200. In this way, the light emission amount of the main light emission can be controlled to an appropriate light emission amount obtained by calculation.
[0054]
Next, the operation flow of the MPU 100 will be described with reference to FIG. First, in FIG. 4A, when the operation of the camera is started, in step 1 (# 01), the input / output ports are initialized and the variables are initialized. In step 2 (# 02), lens information such as focus information and open F number is read from the lens 11. In step 3 (# 03), the strobe information such as the guide number and strobe state is read from the strobe 18.
[0055]
Next, in step 4 (# 04), based on the output of the sensor 33 in the strobe information, it is determined whether or not the direction of the strobe light emitting unit has changed due to the bounce function. At this time, if the direction of the strobe light emitting unit has changed, the process proceeds to step 5 (# 05) to clear the FELK (FE lock) flag (= 0), and if not changed, the process proceeds to step 6 (# 06). .
[0056]
In step 6 (# 06), the states of the operation switches of the camera (not shown) other than SW1 and SW2 are read through the switch sense circuit 110, and various shooting modes are set such as how to determine the shutter speed and how to determine the aperture. .
[0057]
In Step 7 (# 07), it is determined whether or not the switch SW1 for the first stroke of the release button is ON. If it is OFF, the process proceeds to Step 8 (# 08). In step 8 (# 08), it is determined whether or not the photometry timer (a timer for continuing photometry for about 6 seconds after SW1 is turned off) is counting. If counting is in progress, the process proceeds to step 12 (# 12), and if counting has been completed, the process proceeds to step 9 (# 09).
[0058]
In step 9 (# 09), it is determined whether or not SW1 has just changed to OFF. If not, the process proceeds to step 11 (# 11), the FELK flag is cleared, and the flow ends. On the other hand, if it is immediately after the change, the process proceeds to step 10 to start the count of the photometric timer and proceeds to step 12 (# 12).
[0059]
In step 12 (# 12), subject luminance values of six areas on the screen are obtained from the photometric circuit 106.
[0060]
In step 13 (# 13), the exposure amount is determined by a known algorithm from the subject luminance values in the above six areas, and the shutter speed value and the aperture value are determined in accordance with the set shooting mode.
[0061]
In step 14 (# 14), it is determined whether or not the FELK switch is ON. If OFF, the process proceeds to step 18 (# 18), and if ON, the process proceeds to step 15 (# 15).
[0062]
In step 15 (# 15), pre-emission is performed to perform photometry. The contents of this process will be described later.
[0063]
In step 16 (# 16), the FELK flag is set (= 1).
[0064]
In step 17 (# 17), it is determined whether or not the switch SW2 for the second stroke of the release button is ON. When it is OFF, the process proceeds to step 18 (# 18) to perform a focus detection operation. This is based on a known phase difference detection method by the focus detection circuit 105 as described above. Further, in step 18, the lens control circuit 112 is controlled according to the focus state detected by the focus detection operation to adjust the focus of the lens.
[0065]
As described with reference to FIG. 2, there are three points on the screen for focus detection, but it is possible to use a method in which the photographer can arbitrarily set the subject of which point to focus, and prioritize near points. A well-known automatic selection algorithm method based on the basic concept may be used.
[0066]
Returning from step 18 (# 18) to step 2 (# 02), the steps up to this point are repeated as long as SW1 is ON or the photometric timer is counting.
[0067]
In step 17 (# 17), when SW2 is ON, the process proceeds to step 19 (# 19).
[0068]
In step 19 (# 19), pre-emission and photometry are performed. This step 19 is executed using the same pre-flash photometric processing subroutine as in step 15 (# 15).
[0069]
In step 25 (# 25) of the above subroutine shown in FIG. 4B, it is determined whether or not the FELK flag is set. If it is set, the subroutine is terminated as it is. If not set, the process proceeds to step 26 (# 26) and the lens aperture15Perform the release process. This opening process is performed by the function of checking the depth of the subject, etc.15This is because may be narrowed down. In this way, the aperture is set prior to pre-flash.15By opening, the subsequent pre-flash photometry can be performed with accurate and simple calculation.
[0070]
In step 27 (# 27), the charging voltage information of the main capacitor C1 of the current strobe is obtained by transmitting information from the strobe control circuit 200, andlensInformation on the absolute distance from the camera of the subject is obtained by transmitting information from the control circuit 112. Also, subject luminance information from the photometry circuit 106 is obtained.
[0071]
In step 28 (# 28), the amount of pre-emission is determined based on the obtained charging voltage information, absolute distance information, and subject luminance information.
[0072]
In step 29 (# 29), a command is issued to the strobe control circuit 200 so that the determined pre-emission amount is obtained, and pre-emission by flat emission is controlled.
[0073]
In step 30 (# 30), the reflected light of the subject is measured by the multi-segment photometric sensor 7 simultaneously with the pre-emission. The operation at this time will be described in more detail. The luminance of the subject is measured by the multi-division photometry sensor 7 immediately before the pre-flash is emitted, and the difference between the photometric value at the pre-flash and the photometric value immediately before the pre-flash is calculated. As a result, the reflected light from the subject only for the pre-emission light emission is obtained.
[0074]
During pre-emission, the strobe control circuit 200 measures the direct light of the xenon tube 19 with the monitor sensor 31 (PD1), integrates it with the integration circuit 211, and sets the integrated value to A / at the end of pre-emission. D-convert and read. Then, the subroutine ends.
[0075]
In step 20 (# 20) after returning to the main flow, an appropriate integral value of main light emission is calculated from the integrated value of pre-emission, subject reflected light photometric value of pre-emission, exposure value, and the like.
[0076]
In step 21 (# 21), the main mirror 2 is raised prior to the exposure operation, and is moved away from the photographing optical path together with the sub mirror 25.
[0077]
In step 22 (# 22), a command is issued to the lens control circuit 112 so as to obtain an aperture value based on the determined exposure amount, and the shutter control circuit 107 is driven so as to achieve the determined shutter speed value.
[0078]
In step 23 (# 23), the main light emission of the strobe is controlled via the strobe control circuit 200 during exposure in accordance with the driving of the shutter. This main light emission is suppressed to the light emission amount obtained by the calculation of step 20 (# 20).
[0079]
When the exposure operation is completed in this way, in step 24 (# 24), the main mirror 2 that has been retracted from the imaging optical path is lowered and obliquely installed in the imaging optical path, and at the same time, the lens aperture is opened, and the motor control circuit The film is wound up by one frame by 108 and the film running detection circuit 109, and the process returns to Step 2 (# 02).
[0080]
In this embodiment, when the FELK switch is not operated, the lens aperture is set immediately before the exposure operation.15Is opened, pre-emission and photometry are performed, and the main emission and exposure operations are performed after determining the main emission amount (appropriate integral value). At this time, if SW2 is kept ON, continuous shooting is performed and pre-flash is performed every time immediately before exposure. Note that a light emission operation in which pre-light emission is performed immediately before exposure is referred to as a collective light emission mode.
[0081]
When the FELK switch is operated, the main light emission amount (appropriate integral value) is determined by performing pre-emission and photometry by opening the lens aperture regardless of the exposure operation (that is, before operating the release switch). After that, when SW2 is turned on, main light emission and exposure operation are performed with the determined light emission amount. At this time, if SW2 is left ON, continuous shooting is performed, but pre-flashes are not performed every time immediately before exposure, only main flashes are performed, and the main flash levels during continuous shooting are all the same (in other words, The control is performed so that the main light emission amount for the second and subsequent times becomes the same as the main light emission amount for the first time. The operation of performing continuous shooting while fixing the photometric value by the first pre-flash in this way is called an FE lock mode.
[0082]
Furthermore, in this embodiment, as can be seen from step 4 and step 5, when the direction of the strobe light emitting unit is changed by the bounce function after operating the FELK switch, the FE lock mode is canceled and the collective light emission mode is set. Is done.
[0083]
Note that the change from the FE lock mode to the collective flash mode is not limited to the case where the orientation of the flash unit is changed, but by changing shooting conditions that affect exposure, such as changing lenses or changing shooting modes. It may be performed.
[0084]
Next, with reference to FIG. 5, the calculation formula and flow of the calculation part of the appropriate main light emission amount in this camera system will be described.
[0085]
Step101(S101), Subject luminance under natural light is measured, and a weighted average of six photometric areas is obtained by the equation shown in the figure. This step101Corresponds to step 12 in FIG.
[0086]
Here, W (i), which is a weighting count, varies depending on the photometry mode of the main flash control of the strobe 18 and the distance measurement point of natural focus detection, and is set, for example, as shown in the table of FIG. As can be seen from the table, when the metering mode of the main light emission control is the weighted average metering mode, the weighted average is obtained by weighting the distance measurement points for automatic focus detection. When the metering mode is the partial metering mode, the weighting coefficient is applied only to the metering area including the distance measuring point and the weighted average is calculated with all other metering areas set to 0. As a result, one metering mode is calculated. EVb (i) in the photometry area is EVb as it is.
[0087]
In addition, when performing weighted average, the luminance value of each photometric area is log-compressed value EVb (i) obtained by taking the power of 2 and expanding the weighted average, and finally LOG compressed at the base of 2 I am doing so.
[0088]
The value EVb calculated in this way is a step described later.109(S109) Is used when calculating the main light emission appropriate ratio.
[0089]
Step102(S102), Each shooting mode, control value, and the like selected by the photographer's intention, such as the shutter speed priority mode and the aperture priority mode, are input. This step102Corresponds to step 6 in the flow of FIG.
[0090]
Step103(S103), The exposure value EVs including the shutter speed TV and the aperture value AV is determined using the following equation (1) from the shooting mode and control value input in step 2 and the subject brightness value EVb (i).
[0091]
EVs = TV + AV (1)
In order to obtain the exposure value EVs, the step101The weighted average value EVb obtained in step 1 may be used, or a well-known divided photometry calculation algorithm may be used.
[0092]
Step104(S104), Measure the subject brightness just before the pre-flash,101The weighted average value EVa is calculated using an arithmetic expression similar to the above. This step104Corresponds to step 30 in the flow of FIG.
[0093]
Here, even though the metering has already been performed in Step 1,104In this case, the photometry is performed again when the SW1 is turned on, and when the SW2 that is about to start the exposure operation is turned on. The photographer changes the framing and the state of the subject is changed. This is because it may have changed.
[0094]
However, step104In this case, photometry is performed in a short time in accordance with the fact that the subsequent pre-light emission is performed in a short time in order to prevent waste of energy and to reduce glare on the side to be photographed. Specifically, as shown in FIG.101(S101), Photometry is performed for a relatively long time (for example, 10 ms) in order to minimize the influence of flicker when photographing with a fluorescent light source.104(S104) At the subsequent pre-flash (S108) In the same short time (for example, 1 ms or less) as the photometry.
[0095]
Step104Metering and stepping108This photometry is preferably performed close in time so that the photometric conditions of the two, excluding the presence or absence of flash emission, are matched as much as possible.
[0096]
The subject brightness EVa calculated in this way is a step described later.109Is used to calculate the main light emission appropriate ratio.
[0097]
Then step107(S107) Controls pre-flash, but the amount of pre-flash is105(S105), Step106(S106) Is determined. Step 7 corresponds to step 29 in the flow of FIG. 4, and step 5 corresponds to step 27. Also step106Corresponds to step 29.
[0098]
Step105Then, the charging voltage Vc of the main capacitor C1, the subject brightness EVa, and the subject distance Dist are input. And step106Then, the pre-emission amount Q is calculated using the following equation (2).
[0099]
Q = k × F1 (Vc) × F2 (EVa) × F3 (Dist) (2)
Here, as shown in FIG. 7A, the value of the first function F1 (Vc) changes substantially in proportion to the charging voltage Vc. Therefore, when the charging voltage Vc is high, the pre-emission amount Q is increased to increase the dynamic range of photometry, while when the charging voltage Vc is low, the pre-emission amount Q is reduced to prevent energy shortage during main emission. Can do.
[0100]
Further, as shown in FIG. 7B, the value of the second function F2 (EVa) changes substantially in proportion to the subject brightness EVa except when the subject brightness EVa is low to some extent and high to some extent. For this reason, when the subject brightness EVa under natural light is high, the pre-emission amount Q can be increased to prevent the reflected light of the subject due to pre-emission from being buried in the brightness under natural light, and when the subject brightness EVa is low By reducing the light emission amount Q, it is possible to prevent the person who is the subject from being pre-lighted from feeling dazzling. The reason why the value of the second function F2 (EVa) is constant when the subject brightness EVa is low to some extent and high to some extent is that it is difficult to increase or decrease the pre-emission amount in hardware.
[0101]
Further, as shown in FIG. 7C, the value of the third function F3 (Dist) changes substantially in proportion to the subject distance Dist, except when the subject distance Dist is close to some extent and far away. For this reason, when the subject distance Dist is far, the pre-emission amount Q is increased to prevent the pre-emission light from reaching the subject and the reflected light cannot be obtained. When the subject distance Dist is close, the pre-emission amount Q is decreased. Thus, it is possible to prevent the person who becomes the subject from feeling dazzled by the pre-flash. The reason why the value of the third function F3 (Dist) is constant when the subject distance Dist is close to a certain extent and when it is a certain distance is the same as the reason for the second function.
[0102]
Step108(S108), The reflected light intensity from the subject at the time of pre-emission is measured at the timing shown in FIG.101,104The weighted average value is calculated using the same calculation formula as above. Step108Corresponds to step 30 in the flow of FIG.
[0103]
Step109(S109), The light emission amount of the main light emission appropriate for the pre-light emission is calculated using the following equation (3).
[0104]
r = ln₂(2^EVs-2^EVb) -Ln₂(2^EVf-2^EVa) ... (3)
In the first term of this equation, the exposure value (EVs) and the subject luminance photometric value (EVb) are expanded by taking a power of 2, and the latter is subtracted from the former, and finally the LOG compression is performed at the base of 2. . By the calculation of this term, it is possible to calculate the exposure amount that is insufficient for the subject brightness under natural light. That is, in the first term, the calculation is performed based on the idea of obtaining an appropriate exposure by adding the luminance under strobe light to the luminance under natural light. In the second term, the exposure value (EVf) at the time of pre-emission and the photometric value (EVa) of the subject luminance immediately before the pre-emission are expanded by taking a power of 2, and the latter is subtracted from the former. LOG compression is done at the bottom. By the calculation of this term, it is possible to calculate the subject reflected light luminance of only pre-light emission obtained by subtracting the subject luminance under natural light.
[0105]
Then, by subtracting the second term from the first term, the ratio r of how much the light emission amount of the main light emission should be increased / decreased relative to the pre-emission can be calculated in order to make the total exposure appropriate.
[0106]
Step101(S101), An integrated value pre obtained by directly measuring pre-emission. int is calculated. Step101Corresponds to step 30 in the flow of FIG.
[0107]
Step111(S111), Using the following equation (4), the proper integral value main emission main int is calculated.
[0108]
main int = pre int + r + TV-t pre + c (4)
Note that the variables used in this equation are all LOG compressed numbers. As can be seen from this equation and FIG. 6, the light emission amount of the main light emission (flash light emission) is the light emission intensity (pre int-t step to pre)109According to the photographer, the amount of light emitted when a flat light is emitted during the shutter opening time (TV) with the light emission intensity obtained by adding the ratio r obtained in step 1 (actually, light emission intensity r times that of pre-light emission). It is set to the same value as a value obtained by adding the correction coefficient (c) such as the set dimming correction amount.
[0109]
Step112(S112Step by step111The light emission amount of the main light emission is controlled based on the appropriate integral value obtained in step (1). This step112Corresponds to step 23 in the flow of FIG.
[0110]
As described above, in the camera system of the present embodiment, since the pre-flash is made variable, it is possible to realize pre-flash metering that does not make the photographed person feel glare, and the main light is measured by measuring the direct light of the strobe. Since the amount of light emission is controlled so as to have an appropriate integral value, appropriate exposure can be stably obtained without being influenced by the situation of the subject, the difference in composition, and the type of film.
[0111]
If the FE lock mode is selected and the release button is kept pressed, continuous shooting can be performed with a constant strobe emission amount (that is, the same exposure).
[0112]
In addition, when the shooting conditions are changed before the exposure operation after selecting the FE lock mode, the pre-flash metering is performed again by changing to the collective flash mode. Corresponding appropriate exposure can be obtained.
[0113]
The present invention can be applied to a camera system using an image recording medium other than film, and can also be applied to a camera system using an image recording medium in which shooting information can be written by a method other than magnetism.
[0114]
Moreover, you may use this invention combining the above embodiment and modification, or those technical elements as needed.
[0115]
Moreover, the present invention is applied to various types of cameras such as single-lens reflex cameras, lens shutter cameras, and video cameras, optical devices other than cameras, and other devices, and further to these cameras, optical devices, and other devices. The present invention can also be applied to a device or an element constituting the device.
[0116]
(Relationship between embodiment and claims)
The MPU 100, the strobe control circuit 200, the main capacitor C1, the xenon tube 19, the light emission stop circuit 204, and the like in the embodiment constitute a strobe that performs pre-light emission and main light emission as defined in the claims. Further, the multi-division photometry sensor 7 and the photometry circuit 106 in the embodiment correspond to means for performing photometry in the claims.
[0117]
  The sensor 33 in the above-described embodiment corresponds to a detection unit that detects a change in imaging conditions according to claim 3.(Note thatIn the above embodiment, Step 5 (# 05) and Step 12 (# 12) in FIG.Pre-flash reflashEquivalent toIs processing).
[0118]
In addition, although the above is the correspondence of each structure of this invention and each structure of embodiment, this invention is not restricted to the structure of these embodiment, The structure of the mechanism or embodiment shown to the claim has it. Any configuration that can achieve the function may be used.
[0119]
【The invention's effect】
  As described above, in the camera system of the present invention, photometry is performed a plurality of times before the pre-flash,Multiple metering operationsOf which, the time required for the first photometric operation performed immediately before the pre-flashTo be the same as the time required for the second photometric operation performed during pre-flash, andFirstAnd secondOther than the metering operationotherShorter than the time required for metering operationIn addition to setting, the light emission amount of the main light emission is determined using the photometric results obtained by the first and second photometric operations.For this reason, a proper exposure can be obtained stably without being influenced by the difference in the situation or composition of the subject and the type of film.
  Further, it is possible to prevent waste of pre-flash energy and to reduce glare on the side to be photographed.
  Further, if pre-emission and photometry are performed with the aperture of the photographing lens opened, photometry using pre-emission can be accurately performed even when the lens aperture is reduced during preview.
[0120]
  further,If the shooting conditions are changed after the pre-flash but before the main flash, the pre-flash isby doingFor example, even if the shooting conditions such as the direction of the flash or the shooting mode are changed after the first pre-flash photometry value is fixed, accurate metering and proper mains corresponding to the changed shooting conditions are possible. Light emission can be controlled.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of an optical system of a camera system according to a first embodiment of the present invention.
FIG. 2 is a view of a viewfinder of the camera system.
FIG. 3 is a block diagram of an electric circuit of the camera system.
FIG. 4 is a control flowchart of the camera system.
FIG. 5 is a control flowchart of the camera system.
FIG. 6 is an operation concept diagram of the camera system.
FIG. 7 is a graph showing a control function of the camera system.
FIG. 8 is a table showing a photometric method in the camera system.
FIG. 9 is a conceptual diagram of a conventional TTL light control optical system.
[Explanation of symbols]
7 Multi-segment photometric sensor
19 Xenon tube
31 Monitor sensor
C1 Main capacitor

Claims (4)

A camera system for performing photometry by pre-flashing the flash before the main flash of the flash,
A photometric means for performing a photometric operation a plurality of times in at least one of a plurality of areas in the photographing screen;
Of the photometric operations performed a plurality of times, the time required for the first photometric operation performed immediately before the pre-light emission is the same as the time required for the second photometric operation performed during the pre-light emission, and as well as shorter than the time required for other photometric operation other than the first and second photometric operation, determines the amount of light emission of the main emission by using the photometric result obtained by the first and second photometric operation A camera system.   The camera system according to claim 1, wherein the control unit performs the pre-light emission in a state where an aperture of a photographing lens is opened. Having detection means for detecting that the shooting conditions have been changed;
The camera system according to claim 1, wherein the control unit performs the pre-flash again according to the change of the photographing condition.   The camera system according to claim 3, wherein the photographing condition includes at least one of a direction of a light emitting unit of the strobe, exchange of a photographing lens, and a photographing mode.

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