JPH0334048B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a photometry device for photographing in constant light by emitting light from a flash light source (hereinafter referred to as "auxiliary light source"). PRIOR ART Generally, the purpose of using an auxiliary light source in constant light is to adjust the contrast between different parts of the photographic screen to a desired value. For example, when the main subject is dark compared to the background due to backlighting, etc., an auxiliary light source is used to increase the brightness of the main subject to achieve a desired contrast with the background. However, no photometry device has yet been proposed that is suitable for adjusting the contrast between various parts of the photographic screen as desired by the photographer using an auxiliary light source. In the past, photographers with extensive shooting experience would adjust the lighting based on their experience to obtain the shots they desired, and this was done only qualitatively to control the contrast. However, quantitative control was not carried out. Furthermore, it is extremely difficult for a typical photographer to even qualitatively control the contrast. Purpose/Summary of the Invention It is an object of the present invention to propose a new photometric device suitable for photographing with the contrast between each part of the photographic screen as desired by the photographer using an auxiliary light source. The features of this invention include two light receiving elements that measure two different parts on the shooting screen, and signals Qvfm 1 and Qvfm corresponding to the amount of light received by each of the light receiving elements at the time of the first light emission of the _auxiliary light source. ₂ , and a second photometer that outputs signals Bv ₁ and Bv ₂ corresponding to the brightness of the two parts of the photographing screen when the auxiliary light source is not emitting light, based on the output of the light receiving element. exposure time signal output means for outputting a signal Tvs corresponding to the exposure time; contrast ratio output means for outputting a signal ΔCS corresponding to a desired contrast ratio of the two parts of the photographic screen; In order to reproduce the two parts using the contrast ratio output from the contrast ratio output means, the following formula 2〓 ^cs = 2 _Bv1-Tvs +2 ^Qvfm1+ 〓 ^fx /2 ^Bv2-Tvs +2 ^Qvfm2+ 〓 ^f
The present invention further comprises a calculation means for calculating an amount Δfx indicating how much the light emission amount of the auxiliary light source is changed compared to the first light emission based on ^x . Therefore, by using the photometric device according to the present invention, it becomes possible to perform photography with quantitative contrast control, which has been impossible in the past. Embodiments Hereinafter, the present invention will be described in detail together with embodiments shown in the drawings. First, the basic idea of this invention is to control the contrast in the photographic screen using an auxiliary light source such as a flashlight emitting device. Specifically, the brightness of the two parts is 2 ^Bv1 . , 2 ^Bv2 ,
During measurement, the amount of reflected light from the auxiliary light source emitted from the two parts is 2 ^Qvfm1 , 2 ^Qvfm2 , and the exposure time is 2 ^-Tvs.
If so, adjust the contrast between the two parts to the desired △
To control to cs, find Δfx that satisfies (2 ^Bv1-Tvs + 2 ^Qvfm1+ 〓 ^fx ) / (2 ^Bv2-Tvs + 2 ^Qvfm2+ 〓 ^fx ) = 2〓 _cs ...... (1-2), and then The amount of light emitted by the auxiliary light is changed by 2〓 ^fx compared to the amount of light emitted during measurement. In this way, the contrast between the two parts reproduced on the photoreceptor is controlled to Δcs. FIG. 1 is a block diagram showing one embodiment of the present invention. Note that a signal line with diagonal lines indicates a multi-bit digital signal (or signal line).
PD ₁ and PD ₂ are light-receiving elements that measure different parts of the shooting screen, D ₁ and D ₂ are logarithmic compression diodes,
OA ₁ and OA ₂ are operational amplifiers, BT ₁₁ and BT ₁₂ are logarithmic expansion transistors, and BT ₂₁ and BT ₂₂ are current mirror transistors. Diode D ₁₁ , D ₂₁
, a capacitor C ₁₁ , diodes D ₁₂ , D ₂₂ , and a capacitor C ₁₂ are known logarithmic compression integration circuits. FL is a flash light emitting device for auxiliary light, and FL ₁ is a light emitting unit for preliminary light emission. This pre-flash light emitting unit FL ₁ has a terminal for the closing signal of switch S ₆ on the camera side.
The light is received via j ₃₂ and j ₃₁ and flashes. The switch _S6 on the camera side is closed when a photometry button (not shown) is depressed or in accordance with a release signal (not shown). FL ₂ is a light emitting part for main light emission. This main light emitting section _FL2 emits flash light upon receiving the closing signal of the switch _S5 on the camera side via the terminals _j12 and _J11 . This camera-side switch _S5 is a synchro switch that closes when the shutter (not shown) is fully open. The amount of light emitted from the main light emitting section FL ₂ is greater than the amount of light emitted from the preliminary light emitting section FL ₁ by Δfx. This Δfx is the terminal
The value is input via j ₂₂ and j ₂₁ , but Δfx≧0
Therefore, the amount of light emitted from the preliminary light emitting section _FL1 corresponds to the minimum amount of light emitted from the main light emitting section _FL2 . When the switch S ₆ is closed, the preliminary light emitting section FL ₁ starts emitting light and the timer TI ₁ operates, the switches AS ₁ and AS ₂ are connected to the terminals F ₁ and F ₂ , and the switches AS 3 and AS ₄ are connected to the terminals F ₁ and F 2. will be released. Therefore, in the capacitors C ₁₁ and C ₁₂ , the light receiving elements PD ₁ and PD ₂ at the time of preliminary light emission are
Transistors BT ₂₁ and BT ₂₂ corresponding to the output current of
The current from is logarithmically compressed and integrated. Timer TI ₁
is a certain period of time after the preliminary flash starts (2 ^-Tvc seconds)
Connect switches AS ₁ and AS ₂ to terminals A ₁ and A ₂ ,
Stops integration into capacitors C ₁₁ and C ₁₂ . Therefore, the integrated voltage of capacitors C ₁₁ and C ₁₂ at this time is Qv ₁ = log ₂ (2 ^Bv1-Tvc + 2 _Qvfn1 ) ...... (4-1) Qv ₂ = log ₂ (2 ^Bv2-Tvc + 2 _Qvfn2 )......(4-2) This voltage is maintained. Next, from multiplexer 7, the capacitor
Analog signals from C ₁₁ , terminal A ₁ , capacitor C ₁₂ , and terminal A ₂ are sequentially input to the A-D converter 8,
The A-D converted data is sequentially set to registers 10, 11, 12, and 13 via a demultiplexer 9. Register 10 contains data Qv ₁ corresponding to the output of capacitor C ₁₁ , register 11 contains data Qv ₂ corresponding to the output of capacitor C ₁₂ , and register 12 contains data Bv ₁ corresponding to the signal from terminal A ₁ . , data Bv ₂ corresponding to the signal from the terminal A ₂ are set in the register 13, respectively. When data setting to registers 10 to 13 _{is completed, switches AS 3 ,}
AS ₄ is closed, and the integrated charges of capacitors C ₁₁ and C ₁₂ are discharged and prepared for the next photometry. First, calculations by blocks 15 to 22 will be explained. The subtraction circuits 15 and 16 input the apex value T _vc of the integral time from the block 14 and the data Bv ₁ and Bv ₂ from the registers 12 and 13.
Calculate (Bv ₁ - Tvc) and (Bv ₂ - Tvc). Subsequently, in the subtraction circuits 17 and 18, Qv ₁ - (Bv ₁ - Tvc) = Δ ₁₁ ...... (5-1) Qv ₂ - (Bv ₂ - Tvc) = Δ ₁₂ ...... (5-2) Calculate Δ ₁₁ and Δ ₁₂ as shown in the formula, and ROM1
9 and 20 are the data from the subtraction circuits 17 and 18.
Convert to data corresponding to log ₂ (2〓 ¹¹ -1) and log ₂ (2〓 ¹² -1). In the adder circuits 21 and 22, Qvfm ₁ = (Bv ₁ − Tvc) + log ₂ (2〓 ¹¹ −1)
...(6-1) Qvfm ₂ = (Bv ₂ - Tvc) + log ₂ (2〓 ¹² -1)
......(6-2) is performed to calculate the amounts of reflected light Qvfm ₁ and Qvfm ₂ due to flash light emission during preliminary light emission. Addition circuit 2
The reason why the amount of reflected light Qvfm is derived from 1 and 22 is that 2 ^Qv = 2 ^Bv-Tvc + 2 ^Qvfm (4') and by eliminating Qv from equation (5), 2 ^Qvfm = 2 ^Bv-Tvc (2〓 -1), and by taking log ₂ on both sides, equation (6) is obtained. Next, blocks 301 to 309 were used (1-
2) The calculation for calculating the data Δfx corresponding to the light emission amount during main light emission obtained according to the formula will be explained. 73 is a block that outputs data Δcs corresponding to the contrast between the two parts, and in the adder circuits 301 and 302, (Qvfm ₂ +Δcs), (Bv ₂
+Δcs) is calculated. Next, the subtraction circuit 303,
304 performs the calculation Qvfm ₁ - (Qvfm ₂ + Δcs) = α (30) (Bv ₂ + Δcs) - Bv ₁ = β (31), and ROM 305 and 306 perform the calculation from the subtraction circuits 303 and 304. Data α, β log ₂
(1-2 ^- 〓), convert into data corresponding to log ₂ (2〓-1). 26 outputs data corresponding to the synchronized exposure time Tvs for flash photography, and a subtraction circuit 27 calculates (Bv ₁ -Tvs). and addition circuit 3
In 07 and 308, the calculation Qvfm ₁ +log ₂ (1-2 ^- 〓) (Bv ₁ -Tvs) + log ₂ (2〓-1) is performed, and in the subtraction circuit 309, Δfx = (Bv ₁ -Tvs) + log ₂ (2〓
−1)−Qvfm ₁ −log ₂ (1−2 ⁻ 〓)……(32) is performed to calculate the apex value of the ratio of the preliminary light emission amount to the main light emission amount. This data is D-
The signal is converted into an analog signal by the A converter 310, and is applied to the main light emitting section via terminals j ₂₂ and j ₂₁ . The reason why the apex value Δfx, which is the ratio between the preliminary light emission amount and the main light emission amount, is calculated by equation (32) will be explained. Transforming equation (1-2), we get 2 ^Qvfm1+ 〓 ^fx −2 ^Qvfm2+ 〓 ^cs+ 〓 ^fx =2 ^Bv2+ 〓 ^cs-Tvs −2 ^Bv1-Tvs (33), and from equation (33), (30), Using equation (31) to eliminate (Qvfm ₂ + Δcs) and (Bv ₂ + Δcs), we get 2〓 ^fx・2 ^Qvfm1・(1−2 ^- 〓) = 2 ^Bv1−Tvs・(2〓−1), Taking log ₂ on both sides and rearranging, we get (33)
Δfx shown in the formula is obtained. During actual photographing, the amount of light emitted from the main light emitting section FL ₂ is increased compared to the amount of light emitted from the preliminary light emitting section FL ₁ by a value ^2〓fx corresponding to Δfx inputted through the terminal _j21 . The adder circuit 311 performs the calculation Qvfm ₁ +Δfx=Qvf ₁ (7'-1), and calculates the main light emission to the part where the light receiving element PD ₁ receives light when the main light emitting part FL ₁ emits light. The apex value of the amount of light reflected from the subject by Qvf ₁
is calculated. Data from this adder circuit 311
Qvf ₁ and data from subtraction circuit 27 (Bv ₁ - Tvs)
is input to the subtraction circuit 312 to calculate Qvf ₁ − (Bv ₁ − Tvs) = Δ _L1 (8-1), and this calculated data Δ _L1 is stored in the ROM.
313, the data is converted into data corresponding to log ₂ (2〓 ^L1 +1). 49 is a block to which data corresponding to the apex value Sv of the film sensitivity of the film to be used is output, and the data Sv from this block 49 and the data log ₂ (2〓 ^L1
+1), and data from the subtraction circuit 27 (Bv ₁
−Tvs) are input to the adder circuit 314, and Av ₁ = (Bv ₁ −Tvs) + log ₂ (2〓 ^L1 +1) + Sv
......(34) is calculated. This Av ₁ is determined by the light receiving element when the exposure time is Tvs and the light emission amount of the main light emitting section FL ₂ is increased by ^2〓fx compared to the light emission amount of the preliminary light emitting section FL ₁ .
The apex value of the aperture value is such that the portion that PD ₁ receives light is properly exposed. The reason why the apex value Av ₁ of the aperture value is determined by equation (34) will be explained. The conditions for proper exposure during flash photography are (2 ^Qvf1 + 2 ^Bv1-Tvs )・2 ^Sv = 2 ^Av1 (35). Therefore, from equations (35) and (8-1),
When Qvf ₁ is eliminated, 2 ^Bv1-Tvs・(1+ ^2〓L1 )・2 ^Sv =2 ^Av1 , and by taking log ₂ on both sides, equation (34) is obtained. 315 is a well-known display device, and the subtraction circuit 30
The light emission amount of the main light emitting unit FL ₁ is displayed based on the data Δfx from 9, and the data from the adder circuit 314 is displayed.
Displays the aperture value based on Av ₁ and blocks 26
Displays synchronized exposure time based on data from Tvs. Reference numeral 316 denotes a well-known aperture control device, which controls the aperture based on data Av from the adder circuit 314. Furthermore, 317 is a well-known shutter control device which controls the exposure time based on the data Tvs from block 26. By the way, the explanation based on FIG. 1 was only for the case where the amount of light emission Δfx necessary for the contrast to become Δcs can be derived unconditionally. However, in reality, the control range of the camera's aperture,
There are cases in which data on the controllable amount of light emission cannot be determined due to various limitations such as the control range of exposure time, the upper and lower limits of the amount of light emitted by the flashlight emitting device, and the condition of the subject. Therefore, when applying to an actual camera, it is necessary to take some countermeasures even when the controllable light emission amount data Δfx cannot be determined. The contents of calculations when such measures are taken will be explained below based on the block circuit diagram shown in FIG. In addition, Figure 3 (Figure 3A, Figure 3B)
3C and 3C) is a flowchart of the calculation process in a specific countermeasure mode (corresponding to mode I described below), and will be easier to understand if you refer to it. In addition, in Figures 2 and 3, as an example, 2〓 ^cs = 1 (Δcs
0), that is, when trying to control two different parts so that they receive the same amount of light. The symbols used below will be explained. Δf _M
corresponds to the maximum light emission amount, therefore, 0ΔfxΔf _M
In this case, the amount of light emitted can be controlled. Av ₀ is the open aperture value, Av _M is the maximum aperture value (the aperture value corresponding to the minimum aperture aperture), therefore, Av ₀ Av ₁ Av _M
When , aperture control is possible. The subtraction circuit 321 calculates Qvfm ₁ −Qvfm ₂ =α (30), and the subtraction circuit 322 calculates Bv ₂ −Bv ₁ =β (31). The discrimination circuit 323 sets the terminal a ₁ to "High" when the output data α of the subtraction circuit 321 is α>0, and sets the terminal a ₂ to "High" when α=0.
Make it. On the other hand, the discrimination circuit 324 is the subtraction circuit 322
When the output data β is β>0, terminal _a3 is set to “High”, and when β=0, terminal _a4 is set to “High”
Make it. The discrimination circuits 325 and 326 are Qvfm 1 and Qvfm ₁ , respectively.
Determine whether the data of Qvfm ₂ is greater than the constant value data γ from block 320;
When Qvfm ₁ and Qvfm ₂ <γ, terminals a ₅ and a ₆ are set to “High”. If Qvfm ₁ and Qvfm ₂ are below a certain value γ, it is considered that flash light does not contribute to exposure, so this is a signal for ignoring the amount of reflected light due to flash light emission. Subtraction circuits 327 and 328 input data Bv ₁ and Bv ₂ and the tuning limit exposure time data from block 26.
Based on Tvs, calculate the data of (Bv ₁ −Tvs) and (Bv ₂ −Tvs). _The determination circuits 330 and 331 determine whether the data (Bv ₁ -Tvs) and (Bv ₂ -Tvs) are larger than the constant value data δ from the block 329, respectively.
Tvs) (Bv ₂ − Tvs) < δ, terminals a ₇ and a ₈ are set to “High”. This is (Bv ₁ − Tvs), (Bv ₂ −
If Tvs) is smaller than a certain value δ, it is considered that the amount of light due to the steady light does not contribute to exposure, so the signal ignores the amounts of light (Bv ₁ - Tvs) and (Bv ₂ - Tvs) due to the steady light. A decoder 332 makes only one of the output terminals b ₁ to b ₁₀ “High” in response to signals from the input terminals a ₁ to _{a 8} . Table 1 shows the relationship between the input and output of the decoder 332.

[Table] In Table 1, "1" indicates a "High" signal, "0" indicates a "Low" signal, and "φ" indicates that it may be either "High" or "Low". Next, the contents of the calculations for each of the condition modes shown in Table 1 will be explained with reference to FIG. First, in the mode, terminals a ₁ and a ₃ are “High”
Then, terminal _b1 becomes “High”. In this case, Qvfm ₁ −Qvfm ₂ =α>0 Bv ₂ −Bv ₁ =β>0. Therefore, the arithmetic circuit 333 performs the following calculation: Δfx=(Bv ₂ -Tvs)+log ₂ (1-2 ^- 〓) -Qvfm ₂ -log ₂ (2〓-1) (35). The reason why Δfx is found by equation (35) is that when Δcs = 0 in equation (1-2), 2 ^Qvfm1+ 〓 ^fx −2 ^Qvfm2+ 〓 ^fx = 2 ^Bv2-Tvs −2 ^Bv1-Tvs (36). Therefore, using equations (30) and (31), QVfm ₁ ,
Eliminating Bv ₁ gives 2〓 ^fx・2 ^Qvfm2・(2〓−1) = 2 ^Bv2・(1−2 ⁻ 〓)・2 _−Tvs , and by taking log ₂ on both sides, equation (35) is obtained. Δfx found by the arithmetic circuit 333 is determined by the discriminator circuit 3
At step 34, it is determined whether 0ΔfxΔf _M is satisfied. When 0ΔfxΔf _M , the terminal c ₂ becomes “High” and becomes a signal indicating that flash light emission can be controlled. When Δfx<0, the terminal _c3 becomes "High" and becomes a signal indicating that even the minimum amount of light is emitted too much. When Δfx>Δf _M , the terminal _c1 becomes "High", indicating that the amount of light emitted is insufficient even at the maximum light amount. Therefore, when terminals c ₁ and c ₃ are “High”, the contrast 2〓 ^cs
This signal indicates that it is impossible to control the value to 1. When the terminal _c3 is “High”, the arithmetic circuit 338
Then, assuming Δfx=0, Av ₁ = (Bv ₁ − Tvs) + log ₂ (2〓 ^L1 +1) + Sv
......(34) is calculated. Further, when the terminal c ₂ is “High”, the arithmetic circuit 338 performs the calculation of equation (34) based on Δfx calculated by the arithmetic circuit 333. When the terminal _c1 is "High", the calculation circuit 338 performs the calculation (34) with Δfx=Δf _M. The aperture value Av ₁ calculated by this arithmetic circuit 338 is determined by the light receiving element.
The area that PD ₁ measures is the aperture value that provides the correct exposure. This calculated aperture value Av ₁ is determined by the discrimination circuit 339.
Then, it is determined whether Av ₀ Av ₁ Av _M. When Av ₀ Av ₁ Av _M , terminal d ₂ becomes “High”. At this time, if the terminal c ₂ is also “High”, the terminals Δf, Av,
From Tv, data Δfx from the arithmetic circuit 333,
Data Av ₁ from the arithmetic circuit 338 and data Tvs of the exposure time of the tuning limit from the block 26 are output. 2〓 Photographing is performed where ^cs = 1. If the terminal c ₃ is “High” and the terminal d ₂ is “High”, the selector 346 outputs data of Δfx=0,
Data Av ₁ from arithmetic circuit 338 and block 2
Data Tvs from 6 is output. In this case, in the arithmetic circuit 347, Δfx=0, Tvs, Qvfm ₂ ,
Based on the data of Bv ₂ and Sv, Av ₂ = (Bv ₂ − Tvs) + log ₂ (2〓 ^L2 +1) + Sv
......(37) (Δ _L2 = Qvfm ₂ − (Bv ₂ − Tvs)) is calculated. This Av ₂ is an aperture value at which the portion photometered by the light receiving element PD ₂ is properly exposed. By the way, since exposure control is performed using Av ₁ calculated by the arithmetic circuit 338, the contrast between the two parts (the part where the light receiving element PD ₁ measures light is the proper exposure) is Av ₂ - Av ₁ = Δc ₂₁ (38) There will be. -2.7Δc ₂₁ +2.3 is determined, and if this condition is not satisfied, the terminal _g2 is set to "High" and the warning device 348 indicates that the two parts have too much contrast. , warns you that the area measured by photodetector PD ₂ will exceed the latitude range of color reversal film. In the case of color reversal film, −
This kind of warning is necessary because anything outside the range of 2.7Ev and +2.3Ev will not be reproduced on film. If the terminal c ₁ is "High" and the terminal d ₂ is "High", the selector 346 outputs Av ₁ , Tvs, and Δf _M data, and exposure control is performed based on these values, as well as the same as described above. and arithmetic circuit 34
Av ₂ is calculated in step 7, and if it does not become −2.7Δc ₂₁ +2.3, a warning is issued by the warning device 348. When terminal c ₃ is "High", that is, Δfx < 0, and terminal d ₁ is "High", that is, Av ₁ > Av _M , the steady light is too bright and flash emission is not necessary, or the distance to the copy is If the distance is too short, the amount of reflected light from flashlight emission will be too large. In this case, the logic circuit 343
The output terminal f ₂ becomes “High” and the arithmetic circuit 3
45 operates, exposure calculation is performed using only normal light, Ava and Tva are calculated, and the terminal _f3 becomes "High". The “High” signal from this terminal f ₃ is sent to the terminal g ₁ via the selector 346.
The output is now sent to one input of the OR circuit OR ₀ . The other input of this OR circuit OR ₀ receives a signal from a switch S ₅ for starting main light emission. Therefore, when the terminal _g1 is set to "High", even if the switch _S5 is closed, the output of the OR circuit _OR0 remains "High", and the light emission start signal is output from the terminal _j12 . Also, main light emission is not performed. In this case, the output Tva of the arithmetic circuit 345 is
When Tva<Tvs, the selector 346 may output data of Av _M , Tvs, and Δfx=0 so that the flash light is emitted to a minimum. In this case, the ambient light is relatively dark and the distance to the subject is too short.In such a case, there is an advantage that camera shake can be prevented even if the exposure is slightly overexposed. Even when the terminals c ₃ and d ₁ become “High”, Ava, Tva, and Bv ₂ from the selector 346
It is necessary to issue a warning based on the calculation result of the calculation circuit 347 based on the above. When the terminal c ₃ is “High” (Δfx<0) and the terminal d ₃ is “High” (Av ₁ <Av ₀ ), the arithmetic circuit 340
Assuming Av ₁ = Av ₀ , Δfx = (Bv _{1 −} Tvs) + log ₂ (2〓 ^d1 − 1) − Qvfm ₁ (39) Δd ₁ = (Av _{0 −} Sv) − (Bv _{1 −} Tvs) (40) Perform the calculation. The reason for finding Δfx using equation (39) is
The conditions for proper exposure of the area metered by photodetector PD ₁ are 2 ^Bv1-Tvs + 2 _Qvfn1- 〓 _fx = 2 ^Av0-Sv (41), and from equations (40) and (41), (Av ₀ - Sv ), we obtain equation (39). Δfx obtained by this arithmetic circuit 340 is determined by a discriminating circuit 341 to be 0<
It is determined whether ΔfxΔf _M , and if 0<ΔfxΔf _M , the terminal e ₂ becomes “High” and the selector 34
From 6, data of Av ₀ , Δfx, Tvs is output,
The arithmetic circuit 347 calculates Av ₂ and when a contrast warning is necessary, a warning device 348 issues a warning. The reason why the arithmetic circuit 340 performs calculations when the terminals c ₃ and d ₃ are “High” is because the value calculated for the aperture with Δfx = 0 is because the subject is too dark and Av ₁ <Av ₀ .
This is when Δfx is recalculated as Av ₁ =Av ₀ . Therefore, the recalculated Δfx will not become Δfx < 0 (darkening the subject light), and the terminal
e ₃ will never be “High”. When terminal e ₁ is "High" (Δfx > Δf _M ), terminal d ₃ becomes "High" (Av ₁ < Av ₀ ) and Δfx is recalculated, so the flash light emitting device is not fully emitted. However, the proper exposure will not be achieved. Therefore, in this case, the output f ₁ of the logic circuit 343 is set to “High” to operate the arithmetic circuit 344, and Tvx=Bv ₁ −(Qvfm ₁ +Δf _M ) −log ₂ (2〓 ^t1 −1) (42) Δt ₁ = (Av ₀ - Sv) - (Qvfm ₁ + Δf _M ) (43) is calculated. The data Tvx for this exposure time is
The time is longer than the tuning limit data Tvs, thereby increasing the amount of contribution to exposure by constant light to achieve proper exposure. The reason why the exposure time for proper exposure can be obtained from equation (42) is that 2 ^Bv1-Tvx + 2 ^Qvfm1+ 〓 ^fM = 2 ^Av0-Sv (44) is the conditional equation for obtaining proper exposure, and equations (43) and (44) )
By eliminating the term (Av ₀ −Sv) from the equation, equation (42) is obtained. Then, from the selector 346,
Data of Δf _M , Av ₀ , and Tvx are output. In addition,
As with conventional cameras, TVX issues a camera shake warning if the exposure time is longer than the camera shake limit.
It is desirable to issue a warning if the exposure time is longer than the maximum controllable seconds, and to set the exposure time to the maximum limit. Similarly, the arithmetic circuit 347 calculates Av ₂ based on Δfx, Tvx, Bv ₂ , Qvfm ₂ and Sv and issues a warning. Terminal c ₁ of the discrimination circuit 334 is “High” (Δfx>
Δf _M ), and as Δfx=Δf _M , the arithmetic circuit 338
When Av ₁ is calculated and the terminal d ₃ of the discrimination circuit 339 becomes “High” (Av ₁ >Av ₀ ), the terminal f ₁ of the logic circuit 342 becomes “High” and the arithmetic circuit 3
In step 44, Tvx of equation (34) is calculated, and the same operations as described above are performed. Terminal c ₁ is “High” and terminal d ₁ is “High” (Av ₁
> Av _M ), the arithmetic circuit 340 calculates Av ₁ = Av _M
Δfx is calculated as Δfx, and the determining circuit 341 determines whether Δfx0 is reached. If the terminal e ₂ is “High” (Δfx0), the selector 346 outputs Δfx, Av _M and Tvs calculated by the calculation circuit 340, and the above-mentioned warning calculation by the calculation circuit 347 is performed. Let's do it. Terminal c ₁ is “High”
(Δfx<Δf _M ), Av ₁ is calculated as Δfx = Δf _M , and the terminal d ₁ becomes “High” (Av ₁ > Av _M ), and Av ₁ =
Since we recalculated Δfx as Av _M ,
∆fx>∆f _M is never satisfied, and terminal e ₁ is “High”
It will never become. Furthermore, when the terminal e ₃ becomes "High"(Δfx<0), overexposure will occur even if the minimum aperture is set to Av _M and the minimum light emission is performed. In this case, the output f ₁ of the logic circuit 343 becomes "High" and calculations for natural light photography are performed in the same manner as described above. When terminal c ₂ is “High” (0ΔfxΔf _M ), terminal d ₃
When becomes "High" (Av ₁ <Av ₀ ), the arithmetic circuit 340 calculates Δfx according to equation (39). Then, when the terminal e ₂ becomes “High” (ΔfxΔf _M ), Av ₀ , Tvs, and Δfx are output from the selector 346.
The arithmetic circuit 347 calculates Av ₂ for warning.
Further, when Δfx > Δf _M and the terminal e ₁ becomes “High”, the output f ₁ of the logic circuit 342 becomes “High”, and the arithmetic circuit 344 outputs Tvx according to equation (42).
is calculated, and the selector 346 outputs Avv ₀ , Tvx,
Δf _M is output and Av ₂ is calculated. In addition, Δfx
<0, and the terminal _e3 never becomes "High". When terminal _c2 is “High” (0ΔfxΔf _M ), the terminal
When d ₁ becomes “High” (Av ₁ > Av _M ),
Assuming that Av ₁ =Av _M , the arithmetic circuit 340 calculates Δfx according to equation (39). When the terminal _e2 is “High” at Δfx0, the selector 346 outputs Δfx,
The arithmetic circuit 347 outputs Av _M and Tvs, and performs contrast warning calculations. Further, when Δfx<0 and the terminal e ₃ becomes "High", the output f ₂ of the logic circuit 343 becomes "High" and the calculation for natural light is performed. Note that the arithmetic circuit 340
Δfx calculated in Δfx>Δf _M and the terminal e ₁ will never become “High”. Figure 3 is a flowchart of the calculation contents in the mode as described above, and as will be seen, when each calculated data exceeds the control range, other data is calculated using the data that exceeded the control range. Repair. Next, the case of mode will be explained. In this case, all terminals _a1 to _a8 become "Low" and terminal _b2 becomes "High". In this case, Qvfm ₁ −Qvfm ₂ =α<0 Bv ₂ −Bv ₁ =β<0. Therefore, the arithmetic circuit 333 calculates Δfx by calculating Δfx=(Bv ₂ −Tvs)+log ₂ (2 ⁻⁻ 〓−1) −Qvfm ₂ −log ₂ (1−2〓) (45). This is (1-
If 2〓 ^cs = 1 in formula 2), transforming this gives us
(2 ^Bv1 −2 ^Bv2 )・2 ^-Tvs = (2 ^Qvfm2 −2 ^Qvfm1 )・2〓 ^fx , and using this equation and equations (30) and (31), Qvfm ₁ ,
When B _v1 is eliminated, 2 ^Bv2-Tvs・(2 ^- 〓−1) = 2〓 ^fx・(1−2〓)・2 ^Qvfm2 , and when log ₂ on both sides is taken and rearranged, Δfx shown in equation (45) is obtained. is obtained. In the following, calculations are performed in accordance with the flowchart of FIG. 3, as in the case of mode. In mode, terminals a ₁ , a ₃ , and a ₆ are “High”
become. In this case, Qvfm ₁ −Qvfm ₂ = α>0 Bv ₂ −Bv ₁ =β>0 Qvfm ₂ <γ, and it is considered that the amount of light reflected to the photometry section of the photodetector PD ₂ due to flash light emission does not contribute to exposure.
Qvfm ₂ is ignored in calculations. So (1
−2) Equation becomes 2 ^Qvfm1+ 〓 ^fx = 2 ^Bv2-Tvs −2 ^Bv1-Tvs , and if you eliminate Bv ₁ using equation (31), Δfx = (Bv ₂ − Tvs) + log ₂ (1−2 ⁻ 〓) −Qvfm ₁ (46) is obtained. This calculation of equation (46) is performed,
Δfx is calculated. The following calculations are performed in accordance with the flowchart of FIG. 3, as in the case of mode. Note that the warning calculation performed by the calculation circuit 347 is a calculation using normal natural light, and Av ₂ is calculated. In the case of mode, terminal _a5 becomes “High” and
Terminal _b4 becomes “High”. In this case, Qvfm ₁ −Qvfm ₂ = α<0 Bv ₂ −Bv ₁ =β<0 Qvfm ₁ <γ, and it is considered that the amount of light reflected to the photometry section of the photodetector PD ₁ due to flash light emission does not contribute to exposure. Qvfm ₁ is ignored in the calculation. Therefore, equation (1-2) becomes (2 ^Bv1 −2 ^Bv2 )・2 ^-Tvs = 2 ^Qvfm ₂ ⁺ 〓 ^fx , and when Bv ₁ is eliminated using equation (31), Δfx = (Bv ₂ − Tvs) +log ₂ (2 ^- 〓-1) -Qvfms (47) is obtained. The calculation circuit 333 calculates Δfx by calculating equation (47). In this case, Qvfm ₁ is ignored, so arithmetic circuit 3
At step 45, the calculation Bv ₁ +Sv-Tvs=Av ₁ is performed. Then, if Av ₀ Av ₁ Av _M and 0ΔfxΔf _M , the selector 346 outputs
Outputs Av ₁ , Δfx, and Tvs. Also Av ₀ Av ₁
If 0>Δfx in Av _M , the selector 346 will
Av ₁ , Δfx = 0, outputs Tvs, arithmetic circuit 347
Calculate Av ₂ based on the data of Tvs, Δfx = 0, Qvfm ₂ and Bv ₂ , then calculate Av ₂ − Av ₁ = Δc ₂₁ (38), which must be −2.7Δc ₂₁ + 2.3. terminal g ₂
is set to "High" and the warning device 348 issues a warning that the contrast between the two photometric sections is too high. Further, if Δfx>Δf _M in Av ₀ Av ₁ Av _M , the selector 346 outputs Av ₁ , Δf _M and Tvs,
The calculation circuit 347 performs a warning calculation. If Av ₁ <Av ₀ , the exposure time will be underexposure at Tvs. Therefore, in this case, calculate Bv ₁ + Sv - Av ₀ = Tvx with Av ₁ = Av ₀ , and when 0ΔfxΔf _M , Av ₀ ,
Tvx, Δfx, when 0>Δfx, Av ₀ , Tvx,
Δfx=0, when Δfx>Δf _M , Av ₀ , Tvx, Δf _M
are output from the selector 346, respectively, and the arithmetic circuit 3
At 47, a warning calculation is performed. If Av ₁ > Av _M , the exposure time will be overexposed at Tvs. Therefore, in this case, the calculation Bv ₁ +Sv−Av _M =Tvx is performed. In this case, since Tvx > Tvs, flash photography cannot be performed, so terminal f ₃
Set to “High”. And from the selector
The data of Av _M and Tvx are output, the terminal g ₁ becomes "High", and the output j ₁₂ of the OR circuit OR ₀ remains "High" and no flash is emitted. Further, the arithmetic circuit 347 calculates Bv ₂ +Sv−Tvx=Av ₂ Av ₂ −Av _M =Δc ₂₁ , and if it is not −2.7Δc ₂₁ +2.3, the terminal g ₂ is set to “High” and the warning device 348 is activated. Perform contrast warning. In mode, terminals a ₁ , a ₃ , and a ₇ are “High”
In this case, Qvfm ₁ −Qvfm ₂ =α>0 Bv ₂ −Bv ₁ =β>0 Bv ₁ −Tvs<δ. Therefore, since it is considered that the amount of light Bv ₁ −Tvs due to the steady light incident on the photometry section of the light receiving element PD ₁ does not contribute to exposure, the term (Bv ₁ −Tvs) is ignored. Therefore, equation (1-2) becomes (2 ^Qvfm1 −2 _Qvfn2 )・2〓 ^fx = 2 ^Bv2-Tvs , and when Qvfm ₁ is eliminated and rearranged using equation (30), Δfx=(Bv ₂ − Tvs) − Qvfm ₂ − log ₂ (2〓 −1) (48). The arithmetic circuit 333 performs the calculation of equation (48), and performs the calculation according to the flowchart of FIG. 3 as in the case of the following mode. In the case of the mode, the terminal _a8 becomes "High" and _Qvfm1 - _Qvfm2 =α<0 _Bv2 - _Bv1 =β<0 _Bv2 -Tvs<δ. Therefore, since it is considered that the amount of light Bv ₂ -Tvs due to the steady light incident on the photometry section of the light receiving element PD ₂ does not contribute to exposure, the calculation is performed while ignoring (Bvs - Tvs). Therefore, equation (1-2) becomes 2 ^Bv1-Tvs = (2 ^Qvfm2 −2 ^Qvfm1 )・2〓 ^fx , and if we use equation (30) to eliminate Qvfm ₁ and rearrange it, Δfx = (Bv ₁ − Tvs) −Qvfm ₂ −log ₂ (1 −2〓) (49) The calculation circuit 333 calculates Δfx by calculating the equation (49). The following calculations are the same as for modes. In the mode, terminals a ₁ , a ₃ , a ₆ , and a ₇ become “High”. Therefore, Qvfm ₁ −Qvfm ₂ = α>0 Bv ₂ −Bv ₁ =β>0 Qvfm ₂ <γ Bv ₁ −Tvs<δ, and the terms Qvfm ₂ and (Bv ₁ −Tvs) are ignored. perform calculations. In this case, equation (1-2) becomes 2 ^Qvfm1+ 〓 ^fx = 2 ^Bv2-Tvs, and Δfx = (Bv ₂ - Tvs) - Qvfm ₁ (50) The calculation is performed in the arithmetic circuit 333, and the following is the case of mode. The calculation content is the same as . In the case of mode, terminals a ₅ and a ₈ become “High” and Qvfm ₁ −Qvfm ₂ = α<0 Bv ₂ −Bv ₁ =β<0 Qvfm ₁ <γ Bv ₂ −Tvs<δ. . Therefore, Qvfm ₁ and (B _v2 −Tvs)
The term is ignored in the calculation. Then (1-2)
The formula is 2 ^Bv1-Tvs = 2 ^Qvfm2+ 〓 ^fx , and the calculation Δfx = (Bv ₁ − Tvs) − Qvfm ₂ (51) is performed in the calculation circuit 333, and the following calculations are the same as in the mode case. It will be done. In the case of mode, terminals a ₂ and a ₄ are set to "High", and Qvfm ₁ =Qvfm ₂ Bv ₁ =Bv ₂ . In this case, Δfx takes any value from 0 to Δf _M and becomes 2 ^Qvfm1+ 〓 ^fx +2 ^Bv1-Tvs = 2 ^Qvfm2+ 〓 ^fx +2 ^Bv2-Tvs , and the two parts necessarily have the same luminance. controlled by. In this case, terminal b ₉ of decoder 332
becomes “High” and the operation described below is performed. In the arithmetic circuit 338, Δfx=Δfc(Δfc=
Based on Δf _M /2) and Qvfm ₁ , Bv ₁ , Tvs, and Sv, Av ₁ = (Bv ₁ − Tvs) + log ₂ (2〓 ^L1 +1) + Sv (34) ΔL ₁ = (Qvfm ₁ + Δfc) −(Bv ₁ −Tvs) is calculated. That is, the aperture value Av ₁ that provides appropriate exposure when the amount of light emitted by the flashlight emitting device is set between the minimum light emission and the full light emission is calculated. Then, the determination circuit 339 determines whether the condition of Av ₀ Av ₁ Av _M is satisfied, and when the condition is satisfied and the terminal d ₂ is "High", the selector 346 outputs Δfc, Av ₁ and Tvs. Output data. When Av ₁ < Av ₀ and terminal d ₃ is “High”, the amount of light emitted is insufficient and the exposure is insufficient, so Av ₁ = Av ₀
The arithmetic circuit 340 calculates Δfx = (Bv ₁ − Tvs) + log ₂ (2〓 ^d ₁ − 1) − Qvfm ₁ (39) Δd ₁ = (Av _{0 −} Sv) − (Bv _{1 −} Tvs) (40) Then, calculate Δfx. Then, the determination circuit 341 determines whether ΔfxΔf _M or not, and if ΔfxΔf _M , the terminal e ₂ becomes “High”.
From the selector 346, Av ₀ , Δfx, Tvs
data is output. Δfx＞Δf _M and the terminal
When _e1 is "High", even the maximum amount of light emission will be insufficient. Therefore, the output terminal f ₁ of the logic circuit 342 becomes "High", and the arithmetic circuit 344
Based on the data of Qvfm ₁ , Bv ₁ , and Sv where Av ₁ = Av ₀ and Δfx = Δf _M , Tvx = Bv ₁ − (Qvfm ₁ + Δf _M ) − log ₂ (2〓 ^t1 −1) (42) Δt ₁ = (Av ₀ − Sv) − (Qvfm ₁ + Δf _M ) (43) Calculate Tvx and selector 346
outputs data of Av ₀ , Δf _M , and Tvx. Note that Δfx calculated by the arithmetic circuit 340 is a recalculated value since the amount of light emission is insufficient at Δfc, so that Δfx<0 will not hold. When Av ₁ calculated by the arithmetic circuit 338 becomes Av ₁ > Av _M , the amount of light emission is too large at Δfc, the terminal d ₁ of the discrimination circuit 339 becomes “High”, and the arithmetic circuit 340 Assuming Av ₁ = Av _M , calculate Δfx = (Bv ₁ − Tvs) + log ₂ (2〓 ^d1 − 1) − Qvfm ₁ (39) Δd ₁ = (Av _M − Sv) − (Bv _{1 −} Tvs). Then, recalculate Δfx. If Δfx0, the terminal e ₂ of the discrimination circuit 341
becomes “High” and the selector 346 outputs Av _M ,
Δfx and Tvs data are output. Also, Δfx<0
If the terminal e ₃ becomes "High", the output terminal f ₂ of the logic circuit 343 becomes "High", and normal natural light photography calculations are performed to calculate the data of Ava and Tva. Furthermore, terminal _f3 becomes “High”. As a result, from the selector 346
The data of Ava and Tva are output, and the terminal _g1 becomes "High", so that photography is performed without the flash device emitting light. Also, in this case, Δfx is recalculated because the amount of light emission is too large for Δfc, so Δfx>Δf _M will not hold. For modes XI and XII _, respectively: ;Qvfm ₁ −Qvfm ₂ = α _{>0 Bv 2 −Bv 1 = β < 0} XII; Qvfm ₁ −Qvfm ₂ =0 Bv ₂ −Bv ₁ ≠0; Qvfm ₁ −Qvfm ₂ ≠0 Bv ₂ −Bv ₁ =0. Therefore, as can ^be seen from ^{equation (} 1-2), ^Δfx that satisfies the above equation cannot be calculated in the case of ^fx mode ^~ . Therefore, in these cases, the terminal b ₁₀ of the decoder 332 becomes "High", and the same calculation as in the mode is performed, so that the part measured by the photodetector PD ₁ has the proper exposure, Av ₁ or Δfx or Tvx or Ava or Tva is calculated in the same way as in the mode, and exposure control is performed based on this data. In this case, it is necessary to calculate Av ₂ in the arithmetic circuit 347 based on the data from the selector 346 and issue a contrast warning. In the circuit shown in Figure 2, Δfx that satisfies 2 ^Bv1-Tvs +2 ^Qvfm1+ 〓 ^fx = 2 ^Bv2-Tvs +2 ^Qvfm2 +Δfx (1-2) is calculated, and when Δfx<0 or Δfx>Δf _M , the contrast is reduced by 2. 〓 Judging that it is impossible to control ^cs = 1 (Δcs = 0), Δfx = 0 or Δfx
=Δf _M , the aperture value Av ₁ for the photometry section of the light receiving element PD ₁ to achieve proper exposure was calculated based on Bv ₁ , Qvfm ₁ , Tvs, and Sv. However, the contents of the calculation can also be modified as described below.
When Δfx<0 or Δfx>Δf _M , Δfx=0 or Δfx
= Δf _M , 2 ^Bv1-Tvx +2 ^Qvfm1 = 2 _Bv2-Tvx +2 ^Qvfm2 2 ^Bv1-Tvx +2 ^Qvfm1+ 〓 ^fM = 2 ^Bv2-Tvx +2 ^Qvfm2+ 〓 Calculate Tvx that satisfies ^fM , and calculate the range in which this Tvx can be used for flash photography. If so, the exposure time may be controlled based on the calculated Txv, and when Tvx is outside the range, Av ₁ may be calculated using the limit value as Tvx. In this way, the contrast
2〓 There is an advantage that the controllable range is expanded to ^cs = 1 (Δcs = 0). Note that the calculation for determining Tvx is as follows: Qvfm ₁ −Qvfm ₂ = α<0 (30) Bv ₂ −Bv ₁ = β<0 (31) Taking the case of Δfx=Δf _M as an example, the calculation is as explained in Fig. 2. similarly
By eliminating Qvfm ₁ and Bv ₁ and rearranging, we get Tvx = Bv ₂ + log ₂ (2 ^- 〓-1) - Qvfm ₂ - log ₂ (1-2〓) - Δf _M (52), and this (52) Tvx can be calculated by calculating the formula. Note that, as described in the explanation using FIG. 2, the calculation formula for calculating Tvx differs depending on the conditions of α and β. This is shown in a block diagram in FIG. 4, where the output Δfx of the arithmetic circuit 333 is determined, and Δfx > Δf _M and the terminal c ₁ is "High", or Δfx < 0 and the terminal c ₃ becomes “High”, the arithmetic circuit 351 calculates Δfx=0 or Δfx
Based on the data of =Δf _M and the data of Bv ₁ , Qvfm ₁ , Bv ₂ , and Qvfm ₂ , calculations are performed in the same manner as described above depending on the states of the terminals b ₁ to b ₈ . The calculated Tvx data is then sent to arithmetic circuits 338 and 340 and a data selector 346. According to the above embodiments, each block in the block diagram is shown as a circuit device having an independent function. However, it will be relatively easy for those skilled in the art to learn from this embodiment that these organically coupled circuit devices can be replaced with microprocessors or microcomputers. That is, a predetermined program for executing a series of processes in the above embodiment is stored in the built-in storage means of a microcomputer or an external storage means, and the calculation means, control means for calculations, input/output means, etc. are connected to the program. The control system is designed to achieve predetermined control by operating the system. Further, in this embodiment, two cases of light-receiving elements are shown and explained. However, in other embodiments, one of these two methods may perform average photometry for the entire screen, and the other may perform partial photometry at the center. In yet another aspect, five light receiving elements may be provided, one in the center and the other four in the four corners of the photographic screen, so that the two parts can be manually selected. Alternatively, it is also possible to automatically select a portion where the absolute value of the difference between the central portion and the other four portions is the largest in the measured value when the auxiliary light is emitted, and the central portion. Furthermore, in this embodiment, two portions may be provided in which the absolute value of the difference between the five measured values is maximum. Effects As detailed above, the photometry device according to the present invention compares the amount of light emitted by the auxiliary light source with the amount of light emitted during photometry in order to reproduce two different parts on the photographic screen with a desired contrast ratio. Since it is possible to calculate how much the contrast ratio should be changed, it becomes possible to easily obtain a photograph with a desired contrast ratio.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of an embodiment adapted to accommodate various conditions, and Fig. 3 is a flowchart. The circuit is completed with Figure 3C, and shows the operation process in the mode of the circuit of Figure 2. FIG. 4 is a block diagram of main parts as a modification of FIG. 2. PD ₁ , PD ₂ ... light receiving element, FL ... auxiliary light source,
D ₁ , D ₂ , OA ₁ , OA ₂ , AS ₁ , AS ₂ , BT ₁₁ ,
BT ₁₂ , BT ₂₁ , BT ₂₂ , D ₁₁ , D ₁₂ , D ₂₁ , D ₂₂ ,
C ₁₁ , C ₁₂ , AS ₃ , AS ₄ ...Functional devices constituting the photometric circuit, 7 to 22, 26, 27, 73, 4
9,301-314...Functional devices forming a processing circuit.

Claims (1)

[Claims] 1. Measuring two different parts on the photographic screen 2.
a first photometry means that outputs signals Qvfm ₁ and Qvfm ₂ corresponding to the amount of light received by each of the light receiving elements at the time of first light emission of the auxiliary light source; a second photometry means that outputs signals Bv ₁ and Bv ₂ corresponding to the brightness of the two parts of the photographing screen when the light source does not emit light; and an exposure time signal output means that outputs a signal Tvs corresponding to the exposure time. , a contrast ratio output means for outputting a signal ΔCS corresponding to a desired contrast ratio of the two portions of the photographic screen; and for reproducing the two portions of the photographic screen with the contrast ratio output from the contrast ratio output means. , the following formula 2〓 ^cs =2 ^Bv1-Tvs +2 ^Qvfm1+ 〓 ^fx ／2 ^Bv2-Tvs +2 ^Qvfm2+ 〓 ^f
and a calculation means for calculating an amount Δfx indicating how much the light emission amount of the auxiliary light source is changed based on ^x compared to the first light emission time. photometric device.