JPS6137567B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field This invention is a method for performing photometry by emitting a flash light such as a strobe light in the presence of constant light, and measuring the photometry by emitting a flash light prior to taking a picture. The present invention relates to a photometering device for photographing a subject under flash light and constant light for obtaining exposure information for photographing as described above in advance based on the above. Prior Art In photometry as described above, if a flash is preliminarily emitted and the reflected light from the subject is photometrically integrated during a photometry period that includes the flash emission time, the flash and steady light within this photometry period can be calculated. Information on the total amount of light received can be obtained based on the amount of light received. If the above metering time is equal to the exposure time of the shot to be taken later,
The above information corresponds to information on the total amount of light that can actually reach the film surface during photography when the aperture value is taken into account. However, from the above information, the contribution of only the flash light emission within the above photometry time cannot be determined. OBJECT OF THE INVENTION An object of the present invention is to provide a photometry device as described above, which can determine the contribution of only the flash light emission within the photometry time from the integration result of the flash light and the steady light within the photometry time. It's about doing. Structure of the Invention The photometry device of the present invention measures flash light and steady light during a photometry time including the time of flash emission, integrates the total amount of light received during the photometry time, and converts this total amount of light into corresponding data. a first photometric storage means for storing;
a second photometric storage means that measures only stationary light that is not affected by flash light, and stores data representing information on the intensity of only the stationary light; and a photometric storage unit that measures the photometry time in the first photometric storage unit and the second photometric storage unit. and calculation means for calculating the amount of light received only for the stationary light within the photometry time based on the data stored in the first photometry storage means and the calculation result of the calculation means. It is characterized by obtaining data on the contribution of only flash light emission within a time period. Principle of the Invention Prior to the embodiments of the invention, the principle of the invention will be described below. As shown in Fig. 3, the apex value of the photometry time of the flash Ps when the flashlight emitter is activated is TV ₁ , and the apex value of the integral value of the amount of light received by the flash and steady light within this photometry time TV ₁ is The output of the photometry circuit is BVfa, the apex value of the photometry time when only the constant light Pc is irradiated is TV ₂ , the apex value of the subject brightness at this time is BVa, and the apex value of the subject brightness at this time is BVa, when only the flash from the flashlight generator is irradiated. Let BVf be the apex value of the light reception integral value of only the flash within the photometry time TV ₁ , SV be the apex value of the set film sensitivity, and TV be the apex value of the set exposure time. Note that in each of the above codes, BVfa and BVf indicate the amount of light, and have a different meaning from the original BV (BVa is used in its original meaning), which indicates intensity. On the other hand, let AVf be the exposure control value of the camera when only flash light is irradiated, and AVa be the exposure control value when only steady light is irradiated, and the difference between the effects of both lights Δ
₂ is defined as Δ ₂ = AVf−AVa (1). Of the various data required to calculate the difference in effect, the photometric device provides an output signal BVfa when flash light is irradiated and an output signal BVa-TV ₂ when steady light is irradiated. In addition, the photometry time is predetermined, and its apex values TV ₁ and TV ₂
is a known value. Therefore, the above output signal BVa−
BVa can be found from TV ₂ and TV ₂ . Further, the film sensitivity and shutter speed are data set by a setting device or the like. In the above data, the apex value BVf of the integral value for flash light, the apex value BVa of subject brightness for irradiation with steady light, and the apex value TV ₁ of photometry time are BVfa=log ₂ (2 ^BVf + 2 ^BVa-TV1 )... ...(2) holds true. Transforming this, 2 ^BVfa = 2 ^BVf + 2 ^BVa-TV1 ......(3) Here, BVfa-(BVa-TV ₁ )≡Δ ₁ ......(4) is defined, and from equation (3), BVa-TV By eliminating ₁ , we get 2 ^BVf = 2 ^BVfa (1-2 ^- 〓 ¹ ) ......(5), and by taking the logarithm of both sides, we get BVf=BVfa+log ₂ (1-2 ^- 〓 ¹ ) ......(6) The relationship between is determined. Therefore, log ₂ corresponding to this Δ ₁
By finding (1-2 ^- 〓 ¹ ) and adding this value to BVfa, you can find the apex value BVf of this integral value when only the flash is irradiated. By adding the apex value SV of the set film sensitivity to this BVf, the exposure control value AVf=BVf+SV (7) for the case of flash only can be obtained. Further, from the apex value BVa of the subject brightness when irradiated with only the constant light, the set film sensitivity SV, and the apex value TV of the set exposure time, the standard exposure value for the constant light AVa=BVa+SV−TV (8) is determined. Therefore, the difference Δ ₂ between the effects of both lights can be found from Δ ₂ =AVf−AVa (1) (reappeared). Letting AV be the apex value of the diaphragm aperture that provides proper exposure when irradiated with flash light and steady light, it can be determined as follows. First, the following relationship holds true. 2 ^AV = 2 ^AVf + 2 ^AVa ......(9) Using (1) to eliminate AVf from equation (9), 2 ^AV = 2 ^AVa (1+2〓 ² ) ......(10) and take the logarithm of both sides. and AV=AVa+log ₂ (1+2〓 ² ) ......(11), and log ₂ corresponding to the difference Δ ₂ between the effects of the two lights.
By determining (1+2〓 ² ) and adding it to the exposure control value AVa for steady light, an appropriate aperture aperture value AV can be determined. An embodiment of the present invention will be described below with reference to drawings in which it is used in a light meter. In this example, a microcomputer is used for calculation and control, but since it is difficult to perform logarithmic calculations using a microcomputer,
Assuming that the resolution of Δ ₁ and log(1-2 ^- 〓 ¹ ) is 0.1, multiply this value by 10 and obtain log ₂ according to Table 1.
Find (1-2 ^- 〓 ¹ ).

[Table] The subscript H in Table 1 represents 16 numbers. Also, log ₂ (1+2〓 ² ) for Δ ₂ is AVa and
Determine the magnitude of AVf, and when AVa<AVf, AVa−AVf=Δ ₂ ′……(12) When AVa≧AVf, AVf−AVa=Δ ₂ ″……(13) Find this Δ ₂ ′, log _{2 (} 1+2〓
² ) is calculated according to Table 2.

【table】

[Table] And for Δ ₂ ′, AV=AVf+log ₂ (1+2〓 ² ′) ………(14) For Δ ₂ ″, AV=AVa+log ₂ (1−2〓 ² ″) ………( 15) Find. In Fig. 1, numeral 1 is a light-receiving element that is placed in the photometering window of an exposure meter, and generates a signal proportional to the amount of light received by receiving steady light and flash light.This light-receiving element 1 is connected to the input terminal of an operational amplifier 2. be done. A logarithmic pressure diode 3 is connected to the operational amplifier 2, and an output obtained by logarithmically compressing the amount of input light is obtained at the output terminal of the operational amplifier 2. A constant current source 4 and a resistor 5 are connected to a non-inverting input terminal of the operational amplifier 2, as well as a transistor 6 which is turned off during steady photometry. The transistor 6 becomes non-conductive when measuring only steady light, and the output of the operational amplifier 2 is the sum of the potential obtained by logarithmically compressing the output current of the light receiving element 1 with the diode 3 and the potential of the constant current source 4 and the resistor 5. However, the collector current of the transistor 7 is the amplified output current of the light receiving element 1. Further, during photometry when a flash is irradiated, the transistor 6 becomes conductive and the non-inverting input terminal of the operational amplifier 2 becomes the ground potential. This is to prevent the output of the operational amplifier 2 from increasing when the flash is irradiated and the log characteristic between the voltage between the base and emitter of the transistor 7 and the collector current no longer holds true. When calculating the exposure control value from the A-D conversion value of the photometric output when irradiated, the shift of the A-D conversion value due to the elimination of the raising amount by the constant current source 4 and resistor 5 is offset. The factors for the calculation are set as follows. Reference numeral 7 designates the aforementioned logarithmic expansion transistor, whose base is connected to the output terminal of the operational amplifier 2, and whose collector is connected to the collector of the transistor 8 and the base of the transistor 9. transistor 9
A logarithmic compression circuit consisting of diodes 10 and 11 and a capacitor 12 is connected to the collector of the light receiving element 1, and a logarithmic compression signal of the amount of light received by the light receiving element 1 is generated in the capacitor 12. 13 is a reset transistor that short-circuits and opens capacitor 12; 14 is a transistor that opens and closes the emitter of transistor 7; Reference numeral 15 is an AD conversion circuit which inputs the voltage of the capacitor 12 and converts an analog signal representing the amount of light received into a digital signal, and the digital signal is applied to a microcomputer to be described later. Reference numeral 16 denotes a push button switch provided on the light meter so as to be freely operable. This switch 16 is turned on by pressing the button once, and turned off by pressing the button a second time. This switch 16 is connected to a control circuit 17 and instructs the exposure meter to start photometry, and is also connected to a flash emitter (not shown), so that when the switch 16 is operated, a flash is emitted. The control circuit 17 controls the switch 16 every time a preset time elapses in response to the engagement
A signal is generated at any one of terminals a, b, c, and d. FIG. 2 is a detailed circuit diagram of the control circuit 17, in which five counters 18-1 to 18-5 and flip-flops 19-1 to 19-5 are provided. Reset terminals 19-1 to 19-5 are connected to switch 16. The set outputs of each flip-flop are indicated by _Q1 to _Q5 . Further, AND gates 20-1 to 20 are connected to the clock input terminals of each counter 18-1 to 18-5.
-5 output terminal is connected. AND gates 20-1 to 20-5 have a clock pulse cp.
is applied, and the signal from the switch 16 is applied to the AND gate 20-1, and the signal from the switch 16 is applied to the AND gate 20-1.
The set outputs of the flip-flops 19-1 to 19-4 at the previous stage are applied to the flip-flops 0-2 to 20-5. Each flip-flop 19-1
to 19-5 are the corresponding counters 18.
-1 to 18-5, and when the count (time measurement) of one counter is completed, the subsequent counter starts counting, and each flip-flop 19-1 to 19-5 is set.
Control signals are sequentially obtained every predetermined time period. Exclusive OR gates 21-1 to 21-4 are connected to the set output terminals of each flip-flop 19-1 to 19-5, and OR gate 2
1-1 to 21-3 are connected as shown,
Respective control signals are generated at terminals a, b, c, and d. The terminals a, b, c, d in FIG. 2 are the terminals a, b, c, d of the control circuit 17 in FIG.
Matches c and d. Referring again to FIG. 1, 23 is a microcomputer for arithmetic control, which includes a ROM 24 (read-only memory) in which instructions and constant data corresponding to the flowcharts shown in FIG. 5 A to C are stored, and a CPU 25. , an I/O port 26. The CPU 25 also includes an 8-bit register ACC, registers #0R to #7R, a geary flag CY, and a zero flag ZY, as well as other logical operation sections, a program counter, a timing control section, and the like. Also, registers #1R and #0R are connected in series to form a 16-bit register #0PR.
I am trying to use it as 27 is a shutter speed setting circuit that outputs a digital signal obtained by transforming the apex value TV of the set shutter speed into 10·(10-TV), and 28 is the apex value of the set film sensitivity.
The film sensitivity setting circuit outputs a digital signal obtained by transforming SV into 10·SV, and the output signals of both circuits 27 and 28 are applied to the I/O port 26. Reference numeral 29 indicates an effect display device that displays the difference _Δ2 between the effects of flash light and steady light as an apex value, 30 indicates an aperture display device that displays the integer part of the apex value of the appropriate aperture value as an F value, and 31 indicates an apex value that indicates the appropriate aperture value. This is a display device that displays the fractional part of a value as an apex value. Next, the operation of the light meter having the above configuration will be explained. Now, when the metering surface of the exposure meter is facing the subject and the push button is pressed to turn on the switch 16, the counters 18-1 to 18-5 and flip-flops 19-1 to 19 of the control circuit 17 are activated.
-5 are reset, terminals a and b are high and terminals c and d are low. Therefore, transistors 6 and 14 become conductive and transistor 13 becomes non-conductive in preparation for photometry. On the other hand, when the switch 16 is turned on, a flashlight emitter (not shown) emits a flashlight Ps as shown in FIG. This light emission is superimposed with the constant light Pc and is received by the light receiving element 1, and the light receiving current is transmitted to the amplifier 2.
It is logarithmically compressed and amplified by transistor 7, and further logarithmically compressed by transistors 8 and 9 and diodes 10 and 11 according to the operation shown in Japanese Patent Publication No. 50-28038.
It is integrated into 2. On the other hand, in the control circuit 17, the clock pulse is passed through the AND gate 20-1 to the counter 18-1.
is applied, and the time corresponding to the flash is measured. Then, when a predetermined period of time shown in FIG. 4 has elapsed, the counter 18-1 produces a count output, and the flip-flop 19-1 is set. As a result, the terminal a becomes low, turning off the transistors 6 and 14, and the terminal d becomes high, giving a command to the AD conversion circuit 15, which converts the integrated voltage of the capacitor 12 into a digital signal. The output voltage of the capacitor 12 is a logarithmically compressed value of the amount of received flash light, and is 10·(BVfa+K ₁ ). This value is given to the microcomputer. Further, after the time indicated by the arrow in FIG. 4 has elapsed, the counter 18-2 completes counting and flip-flop
9-2 is set and terminal c becomes high. Then, at the time shown in FIG. 4, the transistor 13 is turned on, and the capacitor 12 is shortened and discharged. Furthermore, after a certain period of time, the counter 18-3 completes counting, and the flip-flop 19-3 is set.
At the time shown in Figure 4, terminal b becomes high, transistor 14 is turned on, and the constant light is turned on.
Perform photometry on the PC. Then, the output of the light receiving element 1 corresponding to the constant light is charged to the capacitor 12 in the same manner as in the above case. When the counter 18-4 completes counting, the flip-flop 19-4 is set, and the terminal d becomes high again, and the amount of charge in the capacitor 12, that is, the photometric value of the ambient light, is taken into the AD conversion circuit 15, and the digital value 10. BVa+K ₁ ) and sent to the microcomputer 23. And the microcomputer 23 is the above-mentioned 2
Two photometric results 10・(BVfa+K ₁ ) and 10・(BVa+K ₁ )
and 10・added from each setter 27, 28.
(10−TV) and 10・SV, according to the program described below, BVfa−(BVa−TV ₁ )≡Δ ₁ ………(4) (reappearance) BVf=BVfa+log ₂ (1−2 ⁻ 〓 ¹ ………(6) (reappearance) AVf=BVf+SV ………(7) (reappearance) AVa=BVa+SV−TV ………(8) (reappearance) Calculate the effects of flash and steady light. The difference Δ ₂ =AVf−AVa is calculated and displayed on the display device 29, and this Δ ₂
An appropriate aperture aperture value AV=AVa+log ₂ (1+2〓 ² ) corresponding to is calculated, and the integer value thereof is displayed on the display device 30 and the decimal portion is displayed on the display device 31. After the photometry is completed, the switch 16 is turned off by pressing the push button again, and the photometry is completed. Next, the calculation by the microcomputer 23 will be explained with reference to the flowchart shown in FIG. First, after the power is turned on, switch 16 sets register #2R to be on. Note that the photometric output is shifted by the electric potential generated by the current i of the constant current source 4 and the resistor 5 depending on whether the flash is irradiated or not. The apex value TV ₁ for the photometry time during flash irradiation and the apex value TV ₂ for the photometry time for steady light only.
The difference between the apex value and the actual time is larger by a certain value than the difference between the apex values and the actual time. Further, when Δ ₁ =0, that is, BVa-TV ₁ =BVfa, 2 ^BVfa = 2 ^BVa-TV1 = 2 ^BVf + 2 ^BVa-TV ₁ , and 2 ^BVf = 0. Therefore, the flash from the flashlight emitter does not contribute to photographing. Therefore, in step (17), the zero flag is determined and if ZF=1, the terminal e of the I/O port 26 is set to 1.
This fact is displayed on the display device 29 as . After calculating BVa + SV - TV = AV, the program moves to step (79), displays the appropriate aperture value using the commands below that step, and returns to the start. When Δ ₁ ≠ 0, log ₂ (1−
2 ^- Find 〓 ¹ ). First, if _Δ1 is 01H to 0BH, the apex value 10・(10−TV), 10SV, which corresponds to the set exposure time and film sensitivity metering time,
10·(10−TV ₁ ) and 10·(10−TV ₂ ) are stored in registers #0R to #3R, respectively. And in step (9) AD
The first photometric value of the conversion circuit 15, that is, the photometric value of the flash, is taken into the accumulator ACC, and 10·(BVfa+K ₁ ) is written into the register #4R. Here, the constant _K1 prevents the contents of the register from becoming negative. Next, when the second AD conversion, that is, the AD conversion of the photometry result for steady light, is completed, this result will be 64H.
and the contents of register #3R, 10・(10−TV ₂ ), plus the value 10・(BVa+K ₁ ), are set in register #3R in step (14), and the contents of register #3R are set as #2R.
Add the contents of 10・(10−TV ₁ ) and subtract 64H.
10・(BVa−TV ₁ +K ₁ ) are respectively set in register #2R in step (15). Next, in step (16), the difference between registers #4R and #2R, 10Δ ₁ = 10 {BVfa - (BVa - TV ₁ )}, is calculated by log ₂ (1 - 2 ^- 〓 ¹ ) for every difference in Δ ₁ . Since the values of are different, the value of register #2R is determined by subtracting 1 from the contents of the register. That is, each time 1 is subtracted from the contents of register #2R in step (19), 1 is added to register #7R, and when the contents of register #2R become 00H, set the constant _K2 of register #6R, (39) The contents of 16-bit register #6PR, that is, Δ
Set one of 27H to 09H in Table 1 stored at the address in the ROM 24 specified by ₁ +K ₂ to register #5R and jump to the instruction at step (45). The contents of register #5R are -10・log ₂ (1-2 ^-
〓 This value corresponds to ₁ ). When _Δ1 is 0CH _or more, first go to register #5R.
Set 08H, determine whether the contents of register #2R are smaller than 02H, and if smaller, 10・Δ ₁ =
0C _H ~ 0D _H becomes -10・log ₂ (1 + 2 ^- 〓 ¹ ) = 08H
Jump to the command next door (45). Similarly, the operation of subtracting 1 from the contents of register #5R and determining the contents of register #2R is repeated, and at the time of the instruction at step (45), the contents of register #5R are -10・log ₂ (1− 2 ^- 〓 ¹ ). Next (45) step BVfa + log ₂ (1-2 ^- 〓
¹ ), calculate BVf + SV = AVf, BVa + SV - TV = AVa and store 10・(AVf + K ₁ ) in register #4R.
, set 10・(AVa+K ₁ ) to register #3R. Next, in step (49), determine the magnitude of #3R and #4R, and if (#3R) <(#4R), subtract the contents of register #3R from the contents of register #4R in step (53). Difference between flash and steady light effects by calculation
10· _Δ2 is calculated, (#3R)+27H−(#4R) is calculated, and set in registers #1R and #2R, respectively. Here, as is clear from Table 2, adding 27H is log ₂ (1+2〓 ² ) when AVa−AVf≦3.9
becomes 0, and AVa-AVf≧0. Also, when (#3R)≧(#4R), _Δ2 becomes negative, so the terminal f is set to “high” and this is displayed on the display, and (#3R) - (#4R)
Calculate and (#4R) + 27H - (#3R) and set them in registers #1R and #2R, respectively. Next, 00H is set in register #5R, and the contents of register #5R are incremented by 1 while determining which area the contents of register #2R belong to according to Table 2. Then, at the time of the instruction in step (76), the contents of register #5R are 10・log ₂ (1+2〓
² ). Next, determine the size of registers #3R and #4R, add the contents of #5R to the larger one,
Find the aperture opening value 10·(AV+K ₁ ) as appropriate and set this in register #3R. Next, the contents of register #1R are divided by 10, the remainder value and the quotient, that is, the value obtained by decomposing 10· _Δ1 into the integer part and fractional part of _Δ1 , are decoded in the ROM 24,
Next, it is determined whether the content of #3R displayed by the display device 5 via terminal _P4 is within the display limit, and if it exceeds the display limit, terminal g is set to "high", while if the content is below the display limit In this case, the terminal h is set to "high", and the display devices 30 and 31 display this fact. Next, the contents of register #3R, which is the aperture opening value, are divided into an integer part and a decimal part, and the decimal part is converted to an apex value while the integer part is converted to an F value using the ROM 24. indicate. Thereafter, when the switch 16 is released, the process returns to the start. In this embodiment, only the values for the initially set shutter speed TV and film sensitivity SV are displayed, but the calculated 10.
(BVa+K ₁ ) and 10・(BVf+K ₁ ) are stored up to the instruction (85), and after the output command for display, the stored 10・(BVa+K ₁ ) and 10・(BVf+K ₁ ) are respectively If you set it to registers #3R and #4R, read 10・(10−TV) to register #1R, read 10・SV to register #1R, and return to the instruction (46), it will be set at the beginning. It is now possible to calculate and display values when changing the TV or SV without having to re-measure the light. Further, in this embodiment, a dedicated control circuit 17 is used for the timing of photometry and A-D conversion, but these timings can be controlled by a microcomputer without using a dedicated circuit; When calculating various values from the -D conversion value, a microcomputer is used in this embodiment, but it is also possible to provide a dedicated circuit for each. Furthermore, when carrying out this invention, when deriving equation (5) from equations (2) and (4) as an arithmetic method, BVa−
I was trying to erase TV ₁ , but I tried to erase BVfa and set it to 2 ^BVf = 2 ^(BVa-TV1) (1-2 ^- 〓 ¹ ) ......(5'), and take the log ₂ of both sides. For example, BVf = (BVa - TV ₁ ) + log (2 ^- 〓 ¹ - 1)
......(6′). Therefore log ₂ (2〓 ¹ −1) for Δ ₁
You can find it in a table and add this value to BVa−TV ₁ to find BVf. Furthermore, you can also define (BVa−TV ₁ )−BVfa≡Δ ₁ ′ ………(4′) BVf can be found using a similar calculation. In addition, in this example, since the overall appropriate exposure control value AV is calculated, the difference between this AV and AVA can be calculated as the difference between the part that is not irradiated with the strobe light and the part that is irradiated with the strobe light, or You can see the amount of strobe light contribution to the same subject by irradiating it with light. In addition to this embodiment, AV can be determined by adding SV to BVfa to determine AVfa, and assuming the time from the end of strobe light emission to the elapse of the set exposure time as TV', BVa + SV - TV' = AV' You can find 2 ^AV ′ ^a + 2 ^AVfa = 2 ^AV by finding a. Effects of the invention As is clear from the above, according to this invention,
During the photometry time that includes the time of flash emission, the flash light and standing light are measured, and the total amount of light received during the above photometry time is integrated. Since the configuration is configured to calculate the amount of light received only for the steady light within this photometry time from the intensity information and the photometry time in the above integration, the information on the total amount of light received within the above photometry time and only the steady light within the above photometry time are calculated. From the information on the amount of light received, it is possible to obtain data on the contribution of only the flash light emission within the photometry time. Therefore, it is possible to analytically perform photometry for photographing under illumination conditions in which flash light and constant light are mixed.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing an example of a control circuit used in the embodiment of Fig. 1, and Fig. 3 is an example of flashing light and steady light emission states. FIG. 4 is an operation explanatory diagram showing waveforms of the main parts of the control circuit in FIG. 2, and FIGS. This is a flowchart. Ps...Flash, Pc...Standard light, 1...Photodetector, 2...Operation amplifier, 10, 11...Logarithmic compression diode, 12...Capacitor, 15...AD
Conversion circuit, 16... switch, 17... control circuit, 23... microcomputer, 27... shutter speed setting circuit, 28... film sensitivity setting circuit, 29, 30, 31... display device.

Claims (1)

[Claims] 1. A first photometric storage means for photometrically measuring flash light and steady light during a photometric time including the time of flash emission, integrating the total amount of light received during the photometry time, and storing data corresponding to this total amount of light received; , a second photometry storage means for photometering only stationary light that is not affected by flash light, and storing data representing intensity information of only the stationary light;
a calculation means for calculating the amount of light received only for steady light within the photometry time based on the photometry time in the first photometry storage means and the data stored in the second photometry storage means; A photometry device for subjects under flash and steady light, characterized in that data on the contribution of only the flash light emission within the photometry time is determined from the data stored in the storage means and the calculation result of the calculation means.