JPH09101549A - Controller for photographing with flash by camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably photograph a photographic scene, where reflection from the background has a large influence, with a flash. SOLUTION: A CPU 1 calculates the magnification of image in accordance with the subject distance and the focal length detected by encoders 5 and 6 and sets the multi-division dimming control in the case of the magnification of image equal to or larger than a threshold (the practical dimming area of multi-division dimming is only the main object) and sets the FM control in the other case. A flash circuit 9 emits flash by a light emission start signal ST0 from the CPU 1. In the multi-sivision dimming control, a dimming circuit 7 divides reflected light from the object of the flash into plural dimming areas to receive it; and when the weighted average value of the quantity of reception light in each dimming area reaches a prescribed dimming level, a light emission stop signal ST1 is inputted to the flash circuit 9 to stop light emission. In the FM control, the CPU 1 starts counting the light emission time simultaneously with light emission by a counter 101 and inputs the light emission stop signal ST2 to the flash circuit 9 to stop light emission at the time of the end of counting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash photography control device for a camera, and more particularly to so-called flashmatic control for controlling the light emission amount based on the subject distance and a set aperture value, and a plurality of light reflection amounts from the subject of the flash. The present invention relates to a flash photography control device that controls flash photography by dividing the light into areas and performing photometry and combining with multi-division light control that controls the amount of light emission based on the photometry result.

[0002]

2. Description of the Related Art The flashmatic control and the dimming control are known as the flash emission control methods for cameras. In the flashmatic control (hereinafter referred to as FM control), for example, a flash guide number is calculated on the basis of information on a subject distance and a set aperture value, and the light emission time is controlled based on the calculation result to control the light emission amount of the flash. However, it is less affected by the reflectance of the subject and the background, but it is greatly affected by distance measurement accuracy and aperture accuracy, and especially when a short focus lens is used, the distance measurement result due to a minute error in the lens extension amount. Changes greatly and the reliability of the calculated flash guide number is low.

On the other hand, the dimming control controls the amount of light emission in real time based on the reflected light of the flash light from the subject as described above, and is hardly affected by the ranging accuracy and aperture accuracy, but the subject It is characterized by the large influence of the reflectance and the background.

As described above, there are merits and demerits to both light emission control methods, and it is difficult to perform optimum flash light emission control in all shooting scenes and shooting conditions. There has been proposed a flash photography control device for a camera that combines both light emission control methods.

For example, in Japanese Unexamined Patent Publication No. 58-223125, when the focal length of a lens used is longer than a predetermined focal length (in the case of a telephoto lens), the emission of a flash is controlled by FM control so that a predetermined flash distance is obtained. A flash photographing control device of a camera is shown in which the flash emission is controlled by dimming control when the focal length is shorter than the focal length (for a wide-angle lens).

Further, Japanese Patent Laid-Open No. 3-149535 discloses that when the subject distance is closer than a predetermined distance,
A flash photographing control device of a camera is shown in which the flash emission is controlled by the FM control and the flash emission is controlled by the dimming control when the distance is longer than a predetermined distance.

[0007]

SUMMARY OF THE INVENTION The above-mentioned JP-A-58-22
In Japanese Patent Laid-Open No. 3125 and Japanese Patent Laid-Open No. 3-149535, a decrease in the exposure accuracy of FM control in flash photography using a lens with a short focal length is complemented by switching to dimming control. If the FM control is inappropriate due to the control conditions, the control is switched to the dimming control.

However, even when the multi-dimming control is switched under the above conditions, the shooting scene is a person whose background is a wall of high reflectance such as a gold folding screen, and the background portion is included in the dimming area. When the multi-division light control is performed, the amount of flash light reflected from the background is too large, and the light control amount for a person decreases below an appropriate value, resulting in underexposure of the photographed image. On the other hand, when a person without a reflective object in the background is flash-photographed in the dimming area including the background part by multi-division dimming control, there is almost no reflected light of the flash light from the background. The exposure will be overexposed when the photograph is taken.

Therefore, it is desirable to consider not only the control conditions of the taking lens but also the relationship between the dimming area and the shooting scene in the multi-division dimming control in order to perform the exposure control of the flash shooting more preferably. The publication does not disclose any consideration of such conditions.

The present invention has been made in view of the above problems, and flash photography with a suitable exposure by switching between multi-division light control and FM control in consideration of the relationship between the light control area and the shooting scene. The present invention provides a flash photography control device of a camera capable of performing the above.

[0011]

SUMMARY OF THE INVENTION The present invention includes a subject distance detecting means for detecting a subject distance, and a first light emission control means for controlling a light emission amount of a flash light source based on the subject distance and a set aperture value. Light receiving means having a plurality of dimming areas, weight setting means for setting the weight of each dimming area, and reflected light from the subject of the flash light emitted from the flash light source is received by the light receiving means, and each light control is performed. Second light emission control means for controlling the light emission quantity of the flash light source based on an average value obtained by weighting and averaging the light receiving quantity of the area, a focal length detecting means for detecting a focal length, the subject distance and the focal length. Image magnification calculation means for calculating the image magnification from the above, and the calculated image magnification is compared with a predetermined magnification threshold, and when the image magnification is equal to or larger than this magnification threshold, the light emission control of the flash light source is performed by the second light emission control means. Switch to control by It is obtained by a light control switching means (claim 1).

According to the above construction, the image magnification is calculated from the subject distance and the focal length, and when the image magnification is equal to or larger than the predetermined magnification threshold value, the second light emission control means performs flash photography by the multi-division light control. When the image magnification is smaller than the magnification threshold value, the first light emission control means performs flash photography by FM control.

Further, according to the present invention, in the flash photography control device for the camera, the weight setting means is capable of setting a weight pattern for each of a plurality of light control areas, and the magnification is set according to the set weight pattern. It is provided with a threshold changing means for changing the threshold (claim 2).

According to the above construction, the multi-dimming control and FM
The magnification threshold value, which is a switching point between control and control, is changed according to the weighting pattern set in each dimming area.

Further, according to the present invention, in the flash photography control device for the camera, there is provided a mode setting means for setting a dimming mode, and the weight setting means sets a pattern of a predetermined weight based on the set dimming mode. It is set (claim 3).

According to the above construction, the weighting pattern set in each light control area is, for example, the spot light control mode by the light control area at the center of the photographing screen, or the center-weighted control by the plurality of light control areas at the center of the photographing screen. A predetermined pattern is set according to the light mode and the light control mode such as the average light control mode of the entire photographing screen. Therefore, the switching point between the multi-division light control and the FM control changes depending on the difference in the light control mode.

Further, according to the present invention, in the flash photography control device of the camera, there is provided information detection means for detecting information of the photographing lens relating to the projection range of the subject light image with respect to the dimming area, and the weight setting means detects the information. A pattern with a predetermined weight is set based on the information of the taken photographing lens (claim 4).

According to the above construction, the weighting pattern set in each light control area is a subject light image for the light control area such as the distance from the pupil position of the photographing lens to the film surface or the set aperture value. A predetermined pattern is set based on the information of the photographing lens that affects the projection range of the.
For example, when the projection range of the subject light image for the light control area is concentrated in the center of the screen and the light control area is substantially narrowed, a weighting pattern for the center-weighted light control mode is set.

Further, according to the present invention, in the flash photography control device of the camera, there is provided format setting means for setting a print format, and the weight setting means sets a predetermined weighting pattern based on the set print format. (Claim 5).

According to the above configuration, the pattern of weights set in each dimming area is, for example, a high-definition format printed in high-definition size, a standard format printed in standard size, a panoramic format printed in panoramic size, etc. A predetermined pattern is set according to the print format of. Therefore, the switching point between the multi-division light control and the FM control changes depending on the print format.

According to the present invention, in the flash photography control device of the camera, there is provided subject distance comparison means for comparing the detected subject distance with a predetermined distance threshold, and the light emission control switching means has an image magnification of the magnification. Less than the threshold and
When the subject distance is equal to or less than the distance threshold, the light emission control of the flash light source is switched to the control by the second light emission control means (claim 6).

According to the above construction, the image magnification is calculated from the subject distance and the focal length, the subject distance is detected, the image magnification is smaller than the predetermined magnification threshold, and the subject distance is less than the predetermined distance threshold. At this time, flash photography is performed by the multi-division light control by the second light emission control means.

[0023]

1 is a block diagram of a control circuit relating to a flash photography control apparatus for a camera according to the present invention.

In FIG. 1, a CPU 1 is a control circuit which is composed of a microcomputer and which centrally controls the photographing operation of the camera. The camera has a light emission control function by FM control and T
TL (Through the taking Lens) has a light emission control function by multi-division light control of direct photometry,
The PU 1 also controls the light emission timing and the light emission amount of the flash circuit 9 by the FM control and the multi-division light control.

The CPU 1 has a built-in counter 101 for counting the light emission stop timing in the FM control.

The DX circuit 2 is a DX attached to a film container.
The code is read using optical means, magnetic means, or the like. DX code has film sensitivity (ISO sensitivity)
Data is included.

The photometric circuit 3 is for measuring the subject brightness. The photometric circuit 3 has a multi-division photometric sensor that divides an object into a plurality of areas to perform photometry, and outputs the photometric data obtained in each divided area to the CPU 1. The photometric circuit 3 is shown in FIG.
2 is composed of an IC chip having a photometric window (photometric area) 301 divided into 14 photometric areas S0 to S13, and is provided above the finder optical system 15 of the camera 10 as shown in FIG. ing.

In the photometric circuit 3, as shown in FIG. 5, 13 hexagonal photometric areas S1 to S13 are provided in a honeycomb shape in a rectangular photometric area 301.
An area surrounding 1 to S13 is a photometric area S0. Further, the photometric circuit 3 is arranged so as to be capable of photometrically measuring an image in a substantially central portion within the finder field frame 21.

The CPU 1 calculates the exposure control value from the film sensitivity and the photometric data input from the photometric circuit 3.

The AF circuit 4 is for automatically adjusting the focus of the camera by the phase difference detection method. The AF circuit 4
As shown in FIG. 6, an AF sensor 41 is provided which captures an image at a substantially center in the finder field frame 21 in two separate images.

As shown in FIG. 2, the AF circuit 4 is provided below the main mirror 16 and at an imaging position equivalent to the film surface F with respect to the taking lens 14, and the taking lens 14 and the main mirror are provided. A part of the optical image transmitted through 16 is reflected to a lower position by a sub mirror 18 provided on the back surface of the main mirror 16, and is further guided to an AF sensor 41 by a mirror 19.

A separator lens 20 is provided between the AF sensor 41 and the mirror 19, and the optical image is separated by the separator lens 20 and then the AF sensor 4 is provided.
An image is formed on the reference portion AF0 and the reference portion AF1.

The AF circuit 4 calculates the focusing data from the deviation of the image forming positions of the standard image captured by the standard unit AF0 and the reference image captured by the reference unit AF1 and outputs it to the CPU 1. The CPU 1 automatically moves the focus by moving the lens group 141 for focus adjustment in the taking lens 14 based on this focus data.

In this embodiment, the single distance measuring method using only one AF sensor 41 is adopted, but a multi distance measuring method using a plurality of AF sensors may be adopted.

The encoder 5 is an encoder for detecting the subject distance D. The encoder 5 is, for example, a bit mark member whose position is coded and is disposed opposite to the stationary side (the boundary cylinder side) and the rotation side (the focus adjustment lens driving side) of the photographing lens 14, and information of each bit of the bit mark member. The focus adjustment lens group 1
The distance information corresponding to the feeding amount of 41 is C as code data.
Output to PU1.

The encoder 6 is an encoder for detecting the focal length f. The encoder 6 has the same configuration as the encoder 5, and outputs information according to the focal length f of the taking lens 14 to the CPU 1 as code data.

The dimming circuit 7 is a circuit for detecting the light emission stop timing of the flash circuit 9 by TTL direct photometry. The dimming circuit 7 has a multi-division dimming sensor that divides the subject into a plurality of regions and receives the reflected light of the flash from the subject, and determines the amount of light received in each divided region (hereinafter referred to as the dimming area). The light emission stop timing of the flash circuit 9 is detected based on the light emission stop signal ST1 at this timing.
Is output to the light emission control signal generation circuit 8.

As shown in FIG. 4, the dimming circuit 7 has 4
It is composed of an IC chip having a light receiving window (light control area) 701 divided into light control areas CA0 to CA3, and as shown in FIG. Is provided in the direction of. Dimming circuit 7
7, three square dimming areas CA1 to CAC arranged horizontally in a rectangular dimming area 701, as shown in FIG.
A3 and a dimming area CA0 surrounding these areas. The light reflected on the film surface F is guided to the light receiving window 701, and the light reflected from the subject is divided into the light control areas CA0 to CA3 and received.

The dimming area 701 is divided in this manner so that the dimming of the main subject is surely performed in portrait photography, and the main subject is also lit when the main subject is arranged around the screen. This is because dimming can be performed relatively easily.

The present embodiment has a horizontally long exposure area G capable of printing in high-definition, panorama and standard sizes, and the size of the horizontally long dimming area 701 is as shown in FIGS. As shown in the figure, the sizes of the above three types of print formats are included in the overlapping area so that the multi-division dimming can be effectively performed regardless of which print format is used.

That is, the size of the exposure area G is set to the lateral dimension W.
_G, when the longitudinal dimension H _G, the dimensional ratio W _G / H _G High-definition format (hereinafter, referred to as H Format.) Has become an aspect ratio 16/9 print region G _H and substantially the same, standard format (hereinafter when captured by the C format called.), vertical dimension of the print area G _C H _C
Is approximately the same as the vertical dimension H _G of the exposure area G, the horizontal dimension W _C is approximately 4/3 of the horizontal dimension W _G of the exposure area G (see FIG. 8), and the panorama format (hereinafter referred to as P format).
If in the shooting, the lateral dimension W _P of the printed area G _P is substantially the same as the lateral dimension W _G of the exposure area G, the longitudinal dimension H _P is exposed regions G
Since the vertical dimension H _G is approximately ⅔ (see FIG. 9), the lateral dimension W of the dimming area 701 is approximately 8 times the lateral dimension W _G of the exposure area G.
0% or less, the vertical dimension H of the dimming region 701 is approximately 60% or less of the vertical dimension H _G of the exposure region G, and the area S of the dimming region 701 is approximately 50% or less of the area S _G of the exposure region G. ing.

The dimming areas CA1 to CA3 are shown in FIG.
As shown in FIG. 0, the exposure area G is set to a predetermined size so that dimming can be performed with reflected light of only the main subject in portrait photography. That is, in this embodiment, the lateral dimension W 'is about 20% of the lateral dimension W _G of the exposure area G below, the longitudinal dimension H of the light adjustment area CA1-CA3' is exposed regions of the light adjustment areas CA1-CA3 is set equal to or less than approximately 10% of the longitudinal dimension H _G of G, the light adjustment areas CA1
Area of ~CA3 S 'is about 10% of the area S _G of the exposure area G
It is as follows.

In this embodiment, the dimming area CA1
CA3 are all the same size, but at least one light control area may be set to the above size.

As shown in FIG. 11, the dimming circuit 7 includes the AF circuit 4 in which the dimming area CA2 is located at the center of the exposure area G.
The light control area CA2 is arranged at a position overlapping with the distance measurement area 411, and the vertical dimension H ′ is different from the distance measurement area 411.
Is approximately three times the vertical dimension H _AF and the horizontal dimension W ′ is the distance measurement area 411.
It is set to be substantially the same as the horizontal dimension H _{AF of} . This alleviates the positional accuracy between the AF circuit 4 and the dimming circuit 7, and ensures that the dimming area C is maintained even if there is some misalignment.
A2 is included in the distance measurement area 411, so that the multi-division light control based on the reflected light from the main subject can be reliably performed.

In this embodiment, the dimming area 701 is used.
Although the central light control area CA2 is overlapped with the distance measurement area 411, the light control area CA1 or CA3 may be overlapped with the distance measurement area 411.

When the multi-distance measuring method is adopted, as shown in FIG. 12, the central light control areas CA1 and CA are used.
2 and CA3 are distance measurement areas 411, 412 and 41, respectively.
3 should be arranged so as to overlap.

FIG. 13 is a circuit configuration diagram of the dimming circuit.
The dimming circuit 7 includes a light receiving section 71 and a light emission stop signal generating section 72. The light receiving section 71 is provided with the four light control areas CA0 to CA0.
Light receiving circuits 711 to 714 having the same circuit configuration for respectively receiving the flash light incident on CA3 and these light receiving circuits 7
An adder circuit 7 for weighting and adding each received signal received by 11 to 714 based on the weight data input from the CPU 1.
And 15.

The light receiving circuit 711 is an SPC (Silicon Phot).
o) a light receiving element 711a, a light receiving element 711a
The amplifier 711b is composed of an operational amplifier for amplifying the photocurrent detected by the amplifier 711 and a feedback diode 711c for logarithmically compressing the output current of the amplifier 711a. The light receiving element 711a is connected between both input terminals of the operational amplifier 711b, and the feedback diode 711c is connected between the output terminal of the operational amplifier 711b and the negative-phase input terminal.

The adder circuit 715 is provided in each of the light receiving circuits 711 to 711.
14, four amplifiers are provided, and the output current of each amplifier is added. The gain of each amplifier is set on the basis of the weight data input from the CPU 1, whereby the output currents of the light receiving circuits 711 to 714 are weighted and added. That is, the output currents of the light receiving circuits 711 to 714 are I1, I2, I3, and I4, and the gain of each amplifier is A
1, A2, A3, and A4, I = (A1 · I1 + A2 · I2 + A3 · I3 + A4 · I ”
The photocurrent of 4) is output.

The light emission stop signal generator 72 includes a dimming transistor Tr1, a diode D1, a capacitor C1, a variable voltage source VR, a switch circuit SW1 and a comparator CO.
Consists MP, the detected photocurrent by the light receiving unit 71 converts the voltage V _C at the capacitor C1, to the voltage V _C is the reference voltage V _R (dimming level) set by the variable voltage source VR Upon reaching, the comparator COMP outputs a light emission stop signal ST1.

The dimming transistor Tr1 is an npn-type transistor, the emitter of which is connected to the constant voltage source and the collector of which is connected to the negative phase input terminal of the comparator COMP. The diode D1 applies a bias voltage to the base of the transistor Tr1 and prevents the photocurrent input from the light receiving unit 71 from flowing to the power supply side. The diode D1 is connected between the constant voltage source and the base in the forward direction. I have.

Further, the capacitor C1 and the switch circuit SW1 are connected between the negative phase input terminal of the comparator COMP and the ground.
Are connected in parallel, and the variable voltage source VR is connected between the positive-phase input terminal of the comparator COMP and the ground.

The switch circuit SW1 is a capacitor C1.
It constitutes a discharge circuit for discharging the residual electric charges of (1), and its opening / closing is controlled by a dimming start signal (pulse signal) input from the CPU 1. The variable voltage source VR is the reference voltage V _R in accordance with the film sensitivity is made can be set,
A predetermined reference voltage V _R is set based on the dimming level signal from the CPU 1.

When the dimming start signal is input, the switch circuit SW1 is momentarily turned off, the residual charge of the capacitor is discharged through the switch circuit SW1, and dimming is started. In the light receiving circuit 711, the photocurrent photoelectrically converted by the light receiving element 711a is logarithmically compressed and output from the amplifier 711b. Similarly, the photocurrents detected by the light receiving circuits 712 to 714 are logarithmically compressed and output.

The respective currents output from the light receiving circuits 711 to 714 are weighted by the adding circuit 715 corresponding to the respective dimming areas, and then added to be input to the base of the transistor Tr1 of the light emission stop signal generating section 72. To be done.

The light receiving portion 71 is provided at the base of the transistor Tr1.
, The collector current flows into the capacitor C1, and the capacitor C1 is charged.
When the charging voltage V _C exceeds the reference voltage V _R , the output level of the comparator COMP is inverted from the high level to the low level, and this inversion signal is output as the light emission stop signal ST1.

As described above, the light emission stop signal ST1 is generated by using the weighted addition value of all the light receiving currents of the light receiving circuits 711 to 714. Therefore, when the light emission stop signal ST1 is used to perform the multi-division dimming control, The light emission amount of the flash circuit 9 is controlled so that the weighted average exposure value of the light control areas CA0 to CA3 becomes appropriate.

The light emission control signal generation circuit 8 generates a light emission control signal SFL by the multi-division light control from the light emission start signal ST0 output from the CPU 1 and the light emission stop signal ST1 output from the dimming circuit 7, and the CPU 1 FM from the light emission start signal ST0 and the light emission stop signal ST2 output from
The light emission control signal SFL is generated by the control.

The light emission start signal ST0 is a rising signal which is inverted from low level to high level, and the light emission stop signals ST1 and ST2 are falling signals which are inverted from high level to low level.

The CPU 1 controls the light emission amount of the flash circuit 9 by selecting either the FM control or the multi-division light control according to the image magnification β and the subject distance D as described later.

When the CPU 1 controls the light emission amount of the flash circuit 9 by the FM control method, the CPU 1 does not output the dimming start signal to the dimming circuit 7 and emits the light emission control signal generating circuit 8
The light emission start signal ST0 is output to the
At 01, the counting of the light emission time T _FM is started. When the counting of the light emission time T _FM is completed, the light emission stop signal ST2 is output to the light emission control signal generation circuit 8.

The light emission time T _FM is the flash light emission time corresponding to the proper light emission amount of the flash circuit 9 calculated from the aperture value F set in the taking lens 14 and the subject distance D detected by the encoder 5. Is.

When the FM control method is selected, the light emission control signal generating circuit 8 outputs the light emission stop signal ST from the dimming circuit 7.
1 is not inputted, the light emission control signal SFL (light emission control signal by FM control) generated from the light emission start signal ST0 and the light emission stop signal ST2 is input from the light emission control signal generation circuit 8 to the flash circuit 9, and the flash circuit 9
The light emission / stop timing and light emission amount are controlled by the light emission control signal SFL.

On the other hand, when controlling the amount of light emission by the multi-division light control system, the CPU 1 outputs the light emission start signal ST0 to the light emission control signal generation circuit 8 and causes the light control circuit 7 to flash the flash circuit 9. The light emission start signal is output and the light emission stop signal ST2 is not output. Dimming circuit 7
Starts the light control by the light emission start signal ST0, and outputs the light emission stop signal ST1 to the light emission control signal generation circuit 8 when the reflected light of the flash light from the subject reaches a predetermined light control level.

When the multi-dimming control method is selected,
Since the light emission stop signal ST2 is not input from the CPU 1 to the light emission control signal generation circuit 8, the light emission control signal SFL generated from the light emission start signal ST0 and the light emission stop signal ST1 is output from the light emission control signal generation circuit 8 to the flash circuit 9. A light emission control signal according to the divided light control is input, and the light emission / stop timing and the light emission amount of the flash circuit 9 are controlled by the light emission control signal SFL.

FIG. 14 is a circuit diagram of the light emission control signal generating circuit 8. In the circuit shown in the figure, the OR circuit 81 takes the logical product of the light emission stop signal ST1 and the light emission stop signal ST12, the AND circuit 82 takes the logical sum of the logical product signal and the light emission start signal ST0, and this logical sum signal Is output as a light emission control signal SFL.

At the same time, the OR circuit 81 outputs the light emission stop signal ST.
1 and the light emission stop signal ST2 are not input, so that when either one is input, the signal is output from the OR circuit 81. Therefore, the AND circuit 82 outputs O
Light emission stop signal ST1 or ST2 input to the R circuit 81
And a light emission start signal ST0.

For example, when the FM control method is selected, as shown in FIG. 15, the OR circuit 81 outputs the light emission stop signal S.
Since T2 is output, the AND circuit 82 outputs a light emission control signal SFL that rises (turns on) at the rising timing of the light emission start signal ST0 and falls (turns off) at the falling timing of the light emission stop signal ST2. To be done.

When the FM control method is selected, A
The ND circuit 82 rises (turns on) at the rising timing of the light emission start signal ST0, and the light emission stop signal ST1.
The light emission control signal SFL that falls (turns off) at the falling timing of is output.

The flash circuit 9 is a circuit for generating a flash of light, and is composed of, for example, the circuit shown in FIG.

The flash circuit 9 includes a power supply battery E, a DC-DC converter 91 for converting the battery voltage V _BAT into a predetermined DC high voltage, and a diode D for rectifying the converter output.
2. A main capacitor C _M that stores the discharge energy of the flash, a xenon tube 92 that generates a flash by discharging the accumulated charge of the main capacitor C _M , a trigger circuit 93 that applies a trigger voltage to the xenon tube 92, and light emission control. The switching element 94 is composed of an IGBT that controls the emission of the xenon tube 92 by the signal SFL.

The power source battery E is a DC-DC converter 9
1 and the main capacitor C _M is connected to
The diode D2 is connected to the output terminal of the C-DC converter 91.
Are connected in parallel via. Further, the xenon tube 92 to the main capacitor C _M, diodes D3 and IGBT
94 series circuits are connected in parallel.

The trigger circuit 93 is mainly composed of a step-up transformer T. One end of the primary winding L1 of the transformer T is connected to the positive electrode of the main capacitor C _M via a series circuit of a resistor R1 and a capacitor C2. One end of the winding L2 is connected to the trigger terminal of the xenon tube 92, and the other ends of the primary winding L1 and the secondary winding L2 are both connected to the negative electrode (earth line) of the main capacitor C _M. The connection point a between the resistor R1 and the capacitor C2 is connected to the cathode of the diode D3,
To the anode of the diode D3.
A resistor R2 is provided on the anode of the diode D3 and the earth line.

The DC-DC converter 91 is the CPU 1
Is driven by the charging control signal SC inputted controlled from the charging of the main capacitor C _M is controlled by the drive control.

In the above configuration, when the DC-DC converter 91 is activated by the charge control signal SC, the DC-DC
The converter 91 outputs a voltage obtained by boosting the battery voltage V _BAT to several 100V (for example, 300 to 400V), and the main capacitor C _M is charged with this boosted voltage. At the same time, the capacitor C2 is charged through the resistor R1 and the capacitor C3 is charged through the resistors R1 and R2 to the polarities shown in the drawing.

After charging the main capacitor C _M , IG
When the light emission control signal SFL is input to the BT 94, the IGBT 94 is turned on at a high level of the light emission control signal SFL (see timing A in FIG. 15), and the series circuit of the xenon tube 92 and the diode D3 is equivalently main. The capacitor C _M is connected in parallel to form a discharge path for the accumulated charge of the main capacitor C _M.

At the same time, the + side of the capacitors C2 and C3 is IG
A high voltage of several kV induced in the secondary winding of the step-up transformer T is applied to the xenon tube 92 as a trigger voltage because it is grounded to the earth line via BT94 and the accumulated charge of the capacitor C2 flows via the IGBT94. On the other hand, the xenon tube 92 is applied with a voltage obtained by adding the voltage of the main capacitor C _{M and} the voltage of the capacitor C3, that is, a voltage that is approximately twice the voltage of the main capacitor C _M ,
As a result, the accumulated charge of the main capacitor C _M is discharged to the series circuit of the xenon tube 92, the diode D3 and the IGBT 94, and flash light emission is performed.

After that, when the emission control signal SFL is inverted from the high level to the low level (see timing B in FIG. 15), the IGBT 94 is turned off and the xenon tube 92 is turned on.
, The light emission path is stopped. Therefore, I
By controlling the ON period of the GBT 94, the light emission amount of the flash circuit 9 is controlled.

Returning to FIG. 1, the lens circuit 10 has a photographing lens.
Aperture value (F _No), Taking lens 1
The distance PZ from the pupil center position of 4 to the film plane F
It is a circuit for detecting the information of the index. Also, print four
The mat setting switch 11 is provided on the camera body and
It is a switch that specifies the format when printing.

In the present embodiment, the exposure area G is set to the H format size as described above, and the film is photographed in the H format. The print format setting switch 11 is a switch for enabling a photographer to designate a format when a photograph taken in the H format is to be printed in the C format or the P format.

When the print format information set by the print format setting switch 11 has a storage unit in a magnetically recordable film or a cartridge in which a magnetic recording unit is formed corresponding to each frame, for example, the magnetic recording is performed. Is recorded in the copy section or the storage section.

The spot dimming instruction switch 12 is provided in the camera body, and is a switch for instructing dimming control by the dimming area CA2 at the center of the photographing screen in the multi-segment dimming control. This is a switch for allowing the photographer to manually specify the light intensity when he / she wants to perform light control centering on the main subject arranged in the center of the photographing screen.

Next, FIG. 17 shows selection setting between the FM control method and the multi-division light control method in flash photography.
This will be described with reference to the flowchart of.

FIG. 17 is a flow chart for controlling the switching setting of the FM control method and the multi-division light control method in flash photography, which is performed at the time of photography preparation processing such as AF / AE control performed by half-pressing the release button.

In this flowchart, the print formats that can be set by the print format setting switch 11 are simplified to H format and P format.

When shifting to this flowchart, first,
Whether or not the spot light adjustment is instructed by the spot light adjustment instruction switch 12 is determined (# 2), and if the spot light adjustment is instructed (YES in # 2), each light adjustment area C
The weights WT0 to WT3 corresponding to A0 to CA3 are set to WT0 = WT1 = WT3 = 0 and WT2 = 1 (# 10), and the threshold value βP of the image magnification β is set to a predetermined value β1 set in advance. (# 12).

If spot dimming is not instructed (#
2; NO), the photographing lens 1 detected by the lens circuit 10
The photographing lens 1 detected by the lens circuit 10 determines whether or not the distance PZ from the center position of the pupil to the film surface F is equal to or less than a predetermined value K1 (for example, 50 mm) (# 4).
4 aperture value (F _No) whether it is a predetermined value K2 (e.g. F8) or (# 6), whether the H format by print format setting switch 11 is set (# 8) Are sequentially determined, and PZ ≦ K1
(YES in # 4), F _No ≧ K2 (YES in # 6) or H
If the format is set (YES in # 8), the weights WT0 to WT3 are set to WT0 = 0 and WT1 =
WT3 = WT2 = 1 is set (# 14), and the threshold value βP is further set to a predetermined value β2 (> β1) (# 16).

Further, PZ> K1 (NO in # 4) and F _No
<K2 (NO in # 6) and if the P format is set (NO in # 8), the weights WT0 to WT3 are set to WT0 = WT1 = WT3 = WT2 = 1 (# 14), Further, the threshold value βP is set to a predetermined value β3 (>β2> β1) set in advance (# 20).

When the spot light control is set, the photographer has instructed the flash photography centering on the main subject arranged in the center of the photographing screen, and therefore only the light control area CA2 in the center of the photographing screen is set. To perform dimming
Only the weight WT2 of the light control area CA2 is set to "1".

When PZ ≦ K1 or F _No ≧ K2, the reflected light from the subject does not sufficiently enter the peripheral portion of the dimming area 701 of the dimming circuit 7, and the dimming area 701 is substantially formed. In the case of narrowing, in this case, the peripheral portion of the dimming area 701 does not contribute much to dimming, so only the weights WT1 to WT3 of the dimming areas CA1 to CA3 in the central portion of the screen are set to “1”, and the center-weighted I am trying to control the light. Also, P
When the format is set, as shown in FIG. 9, since the print area is located at the center of the photographing screen, in order to optimize the exposure of this area, PZ ≦ K1 or _FNo ≧ K
2, the weights WT of the light control areas CA1 to CA3
Only 1 to WT3 are set to "1" to perform center-weighted light control.

On the other hand, when PZ> K1 and F _No <K2, or when the H format is set,
Since there is no problem of narrowing the dimming area 701 and it is considered necessary to perform proper exposure for the entire screen, the weights WT0 to WT3 of all the dimming areas CA0 to CA3 are considered.
Is set to “1” to perform average light control over the entire screen.

The threshold value βP of the image magnification is a switching point for switching between multi-division light control and FM control. The more the light control area is concentrated in the center of the photographing screen, the smaller the threshold βP is in the spot adjustment. The sizes of the substantial light control areas in the light control modes of light, center-weighted light control, and average light control of the entire screen are light control area CA2 and light control areas CA1 to CA1, respectively.
This is because CA3 and light control areas CA0 to CA3 are obtained, the spot light control is the smallest, and the average light control is the largest.

For example, a shooting scene with a highly reflective object in the background such as a person with a gold folding screen in the background (hereinafter referred to as a high reflection shooting scene) or a scene with a low reflectance in the background such as a person against a dark background Scene (hereinafter referred to as low-reflection shooting scene)
In the above, when flash photography is performed by multi-division dimming control and the background is included in the dimming area, the amount of reflected light in the background portion of the flash light greatly affects the exposure of the photographed photograph.

Therefore, in the present invention, when the light control area is affected by the background due to the shooting scene, that is, when the background is included in the substantial light control area, the light emission amount of the flash is controlled by FM control. When the dimming area is not affected by the background (when the background is not included in the substantial dimming area), the light emission amount of the flash is controlled by the multi-division dimming control.

Since the substantial light control area is the smallest in spot light control, the light control area CA2 is small even if the size of the main subject such as a person in the photographing screen is relatively small, that is, the image magnification β is relatively small. Since the person is covered, the switching point βP for switching to the multi-dimming control is minimized. On the other hand, in the average light control, the substantial light control area is the largest, and therefore the size of the main subject such as a person in the shooting screen is relatively large, that is, even when the image magnification β is relatively large, the light control areas CA0 to CA3. Since the background may be included in, the switching point βP is set to the maximum. In the center-weighted dimming, the size of the substantial dimming region is between the spot dimming and the average dimming, so the switching point βP is between the spot dimming and the average dimming.

Incidentally, the concrete threshold values β1 to β3 of the switching point βP are set to appropriate values experimentally or empirically.

When the image magnification threshold βP is set, it is subsequently determined whether or not the image magnification β calculated from the subject distance D and the focal length f is equal to or more than the threshold βP (# 2).
2). Note that the image magnification β is β = k · f / D (k; proportional coefficient) from the subject distance D detected by the encoder 5 by the CPU 1 and the focal length f detected by the encoder 6.
Is calculated by the following equation.

The above discrimination is to estimate whether or not the substantial light control area is completely covered by the main subject. β
If ≧ βP (YES in # 22), it is estimated that the substantial light control area is completely covered by the main subject, so multi-division light control is set (# 26), and the process returns.

If β <βP (NO in # 22), it is further determined whether or not the subject distance D exceeds a predetermined value D1 set in advance (# 24). If D ≦ D1 (#) Two
4; NO), multi-division dimming control is set (# 26), and D
If> D1 (YES in # 24), FM control is set (# 28), and the routine returns.

The determination based on the subject distance D is to determine whether or not the subject is a close-up shot within a predetermined short distance. In close-up photography, a diffusion plate is likely to be attached to the taking lens 14 in order to improve the light distribution characteristic of the flash, but if the subject distance is too short, the light distribution characteristic of the flash may deteriorate.

Therefore, even in a shooting scene in which the substantial light control area is affected by the background, in multi-division light control in close-up photography where the light distribution characteristic of the flash deteriorates, the light emission control is appropriately performed. It is trying to make it.

When the FM control is set by the above-mentioned light emission control setting process, in flash photography, first,
The CPU 1 sets the light emission time T _FM based on the aperture value F, the subject distance D, and the detection accuracy of the subject distance D.
Then, the CPU 1 outputs the charging control signal SC to the flash circuit 9 to charge the flash circuit 9.

After the flash circuit 9 is charged, the CPU 1 outputs the light emission start signal ST0 to the light emission control signal generation circuit 8 at a predetermined timing, and the counter 101
Count of _FM the emission time T is started by. The light emission start signal ST0 is directly input to the flash circuit 9 via the light emission control signal generation circuit 8, and the flash is emitted at this input timing.

When the counting of the light emission time T _FM is finished, the light emission stop signal ST2 is input to the flash circuit 9 via the light emission control signal generation circuit 8, and the light emission of the flash is stopped at this input timing.

On the other hand, when the multi-dimming control is set, the CPU 1 sends the charge control signal SC to the flash circuit 9.
Is output, and the flash circuit 9 is charged. Further, the weight data WT0 to WT are sent from the CPU 1 to the dimming circuit 7.
3 DOO dimming level signal is input, the weighted average value of the light adjustment areas CA0~CA3 of the dimming circuit 7 weight and the reference voltage V _R
Is set.

After the charging of the flash circuit 9 is completed, the CPU 1 outputs the light emission start signal ST0 to the light emission control signal generation circuit 8 at a predetermined timing, and the light control circuit 7 outputs the light control start signal. The light emission start signal ST0
Is input to the flash circuit 9 as it is via the light emission control signal generation circuit 8, and the flash is emitted at this input timing.

Thereafter, when the amount of light reflected from the subject of the flash light received by the light control circuit 7 reaches a predetermined light control level, the light emission stop signal ST2 is sent to the light emission control signal generation circuit 8
, And the flash circuit 9 is stopped at this input timing.

[0108]

As described above, according to the present invention,
A first light emission control mode in which the light emission amount of a flash light source is controlled based on the subject distance and a set aperture value, and the amount of light reflected from the subject of the flash light emitted from the flash light source is divided into a plurality of light control areas for photometry. Then, in the flash photography control device of the camera having the second light emission control mode for controlling the light emission amount of the flash light source based on the result of the photometry, the image magnification is calculated from the subject distance and the focal length, and this image magnification is In the case where the light emission control of the flash light source is switched to the control by the second light emission control means when the magnification is equal to or more than the predetermined magnification threshold, it is estimated that the light control area is completely covered by the main subject from the image magnification. Since the split dimming control is performed, it is possible to adjust the dimming even in the case of a shooting scene that is greatly affected by the background, such as a person with a high-reflectance reflector or a person with a background without a reflector. Relationship between area and shooting scene Thereby enabling suitable exposure flash photography considering.

Further, the weighting pattern of each dimming area can be changed according to the dimming mode, the information of the photographing lens and the print format, and the magnification threshold value is changed according to the set weighting pattern. Even when the light area changes, it is possible to estimate with high accuracy whether or not this main light area is completely covered by the main subject from the image magnification, and consider the relationship between the light adjustment area and the shooting scene. The flash photography described above can be more suitably performed.

When the image magnification is smaller than the predetermined magnification threshold and the detected subject distance is equal to or smaller than the predetermined distance threshold, the light emission control of the flash light source is switched to the control by the second light emission control means. Even in a shooting scene where the dimming area is affected by the background, multi-dimming dimming control is performed in close-up photography where the light distribution characteristics of the flash deteriorate, so a flash that is suitable for close-up photography can also be used. You can take a picture.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control circuit relating to a flash photography control device for a camera according to the present invention.

FIG. 2 is a diagram showing a positional relationship between various sensors provided in a camera and a flash circuit.

FIG. 3 is a diagram showing a photometric circuit.

FIG. 4 is a diagram showing a dimming circuit.

FIG. 5 is a diagram illustrating a photometry position in each divided area of the multi-segment photometry circuit and a finder field frame.

FIG. 6 is a diagram showing a photometry position in a finder field frame of the AF sensor.

FIG. 7 is a diagram showing a relationship between each light control area and a high definition format area in an exposure area of the multi-division light control circuit.

FIG. 8 is a diagram showing a relationship between each light control area of a multi-division light control circuit and a standard format area in an exposure area.

FIG. 9 is a diagram showing a relationship between each light control area and a panorama format area in an exposure area of the multi-division light control circuit.

FIG. 10 is a diagram illustrating a relationship between the size of a light control area of a multi-division light control circuit and the size of a subject in portrait photography.

FIG. 11 is a diagram illustrating a relationship between a photometry area and a light control area.

FIG. 12 is a diagram showing a relationship between a photometric area and a dimming area in the multi-range finding method.

FIG. 13 is a circuit configuration diagram of a dimming circuit.

FIG. 14 is a circuit configuration diagram of a light emission control signal generation circuit.

FIG. 15 is a time chart for explaining the operation of the light emission control signal generation circuit.

FIG. 16 is a circuit configuration diagram of a flash circuit.

FIG. 17 is a flowchart for controlling switching setting between an FM control method and a multi-segment dimming control method in flash photography.

[Explanation of symbols]

1 CPU (first light emission control means, image magnification calculation means, image magnification comparison means, light emission control switching means, weight setting means, changing means, subject distance comparison means) 101 counter 2 DX circuit 3 photometric circuit 301 photometric window 4 AF Circuit 41 AF sensor 5 Encoder (subject distance detecting means) 6 Encoder (focal length detecting means) 7 Light control circuit (second light emission control means) 71 Light receiving part (light receiving means) 701 Light receiving window (light adjusting area) 711 to 714 Light receiving circuit 711a Light receiving element 711b Amplifier 711c Diode 715 Adder circuit 72 Light emission stop signal generation unit 8 Light emission control signal generation circuit 81 OR circuit 82 AND circuit 9 Flash circuit 91 DC-DC converter 92 Xenon tube 93 Trigger circuit 94 Switching element (IGBT) 10 lens circuit (information detecting means) 11 Lint format setting switch (format setting means) 12 spots dimmer instruction switch (mode setting means) 13 camera 14 taking lens 15 viewfinder optical system 16 main mirror 17 pentagonal prism 18 submirror 19 mirror 20 separator lens C _M main capacitor C1~C3 capacitor COMP comparator D1 to D3 diode E battery R1, R2, R3 resistance SW1 switch circuit Tr1 transistor VR variable voltage source

Claims (6)

[Claims] 1. A subject distance detecting means for detecting a subject distance, a first light emission control means for controlling a light emission amount of a flash light source based on the subject distance and a set aperture value, and a light receiving device having a plurality of dimming areas. Means, weight setting means for setting the weight of each dimming area, and reflected light from the subject of the flash light emitted from the flash light source is received by the light receiving means, and the amount of light received in each dimming area is adjusted by the weight. Second light emission control means for controlling the light emission amount of the flash light source based on the weighted average value, focal length detection means for detecting the focal length, and image magnification for calculating the image magnification from the subject distance and the focal length. Computing means,
The calculated image magnification is compared with a predetermined magnification threshold, and when the image magnification is equal to or larger than this magnification threshold, the light emission control switching means for switching and setting the light emission control of the flash light source to the control by the second light emission control means. A flash photography control device for a camera characterized by being provided. 2. The flash photography control device for a camera according to claim 1, wherein the weight setting means is capable of setting a weight pattern for each of a plurality of dimming areas, and the magnification is set according to the set weight pattern. A flash photography control device for a camera, comprising a threshold changing means for changing a threshold. 3. The flash photography control device for a camera according to claim 2, further comprising a mode setting means for setting a light control mode, wherein the weight setting means sets a pattern of a predetermined weight based on the set light control mode. A flash photography control device for a camera, characterized by being set. 4. The flash photography control device for a camera according to claim 2, further comprising: information detection means for detecting information of a photographing lens regarding a projection range of a subject light image with respect to the dimming area, wherein the weight setting means detects the information. A flash photography control device for a camera, wherein a pattern of a predetermined weight is set based on the information of the taken photographing lens. 5. The flash photography control device for a camera according to claim 2, further comprising format setting means for setting a print format, wherein the weight setting means sets a predetermined weight pattern based on the set print format. A flash photography control device for a camera, characterized by being a thing. 6. The flash photography control device for a camera according to claim 1, further comprising a subject distance comparison means for comparing the detected subject distance with a predetermined distance threshold,
The light emission control switching means, when the image magnification is smaller than the magnification threshold and the subject distance is less than or equal to the distance threshold,
A flash photographing control apparatus for a camera, wherein the flash light emission control of the flash light source is switched to the control by the second light emission control means.