JPH0140334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures the photometry by dividing the reproduction field into a plurality of areas, and determines the appropriate photometry output for determining the appropriate exposure of the entire screen from a plurality of photoelectric outputs corresponding to the plurality of areas. This invention relates to a multi-photometering device that calculates and extracts

Various types of multi-photometering devices described above have been proposed. One example of this is JP-A-52-12828.

What has been proposed in this type of conventional split photometry device is how to calculate an appropriate exposure value from a plurality of pieces of photometry information.

However, when this multi-photometering device can be used in an actual camera, there are the following problems. In other words, there is a difference between the distribution of photoelectric output as a photometric output in the field of view (hereinafter referred to as the screen) and the distribution of illuminance on the film surface, so the photoelectric output cannot be used as it is as a photometric output. It is a point. Especially in the case of TTL aperture metering, there is a noticeable difference between the photoelectric output distribution during aperture metering and the film surface illuminance distribution at the aperture value actually used.
It was impossible to ignore.

In the case of conventional photometers using a single photoelectric element output, the photometry target was mainly the center of the screen, which had good proportionality to the aperture value of the lens, for both the photoelectric output of the photodetector and the film surface illuminance. It was not affected by the difference in image quality, and exposure errors were relatively rare. However, in the case of a multi-photometry device, since the peripheral portion of the screen is also independently photometered, the difference between the two distributions described above cannot be ignored.

For example, as shown in _{FIG .}
Let us consider the case where the screen is divided into a 4×6 matrix and photometry is performed. When the subject is on a uniform brightness surface, part A on the screen in Figure 1
The photoelectric output at A' exhibits a distribution as shown in Figure 2a, where the output level drops at the periphery of the screen due to lens vignetting and the cosine fourth law. (In Figure 2, the horizontal axis represents the position within the screen with the center of the screen set to 0.) However, when the image is actually stopped down, the illuminance distribution on the film surface is no longer affected by vignetting, and the photoelectric output is as shown in Figure 2b. It becomes quite flat, like this. If this difference is not taken into consideration, the peripheral area of the screen will be measured darker than it actually is.

The applicant has proposed correcting the obtained photoelectric output using lens setting information so that it approaches the illuminance on the film surface when actually stopping down and photographing (Patent Application No. 1983- No. 151467). However, in the case of shutter priority mode and program mode, the lens is generally set to the minimum aperture, but the aperture that is actually controlled may be wide open, which may cause some inconvenience when used in these modes. . That is, although correction must be made near the maximum aperture, since only information about the minimum aperture value is transmitted from the lens to the camera, there is a drawback that correction cannot be performed when the aperture value to be controlled is at the maximum aperture value.

The present invention corrects photoelectric output in a camera that automatically controls the aperture in shutter priority mode or program control mode by introducing a signal corresponding to the aperture value to be controlled from the exposure calculation circuit. This problem has been solved and the aperture can be detected and corrected even when the aperture is set to the minimum aperture.

FIG. 3 is a block diagram showing the basic configuration of the multi-photometering device of the present invention, and the flow of signals in the case of aperture priority/automatic shutter speed control will be explained using this block diagram.

In the following explanation, BV is subject brightness, AV
is the aperture value, SV is the film sensitivity, and TV is the apex value of the shutter speed. 1 is a photometric circuit, 2 is a multi-photometric processing circuit, 3 is an apex calculation circuit,
4a is an aperture control circuit, 4b is a shutter control circuit,
5 is an information setting section, and 6 is a display circuit. From the photometric circuit 1, if the division is performed as shown in Figure 1,
Photoelectric output P ₁₁ (=BV ₁₁
- AV ₀ : For TTL open metering, the same applies hereafter), R ₁₂ (=
BV ₁₂ −AV ₀ ), ..., P ₄₆ (=BV ₄₆ −AV ₀ ) are obtained. Note that the number of each photodetector and the number of each photoelectric output are the same in order to make the correspondence clear. This output is input to the multi-photometering processing circuit 2, where it undergoes a series of arithmetic processing and is unified as an estimated value of appropriate exposure. Compute the calculation power P ₁₀₀ = BV _aos −AV ₀ . Examples include Japanese Patent Application Laid-Open No. 52-12828, and Japanese Patent Applications No. 54-23019 and No. 54-23020 filed by the applicant. The apex calculation circuit 3 receives film sensitivity information P ₁₀₁ =SV from the information setting section 5, open aperture information P ₁₀₂ =AV ₀ , set aperture information P ₁₀₃ =(AV-AV ₀ )M, and shutter speed information.
P ₁₀₄ = TV _M , mode information P ₁₀₅ , and calculation output regarding brightness calculated by the multi-photometry processing circuit 2 P ₁₀₀₁ =
BV _aos -AV ₀ is input, and the following apex calculation is performed (the subscript M represents a set value).
For example, when the aperture priority mode is selected by the mode information _P105 , the aperture control signal _P107 = _P103 = (AV- _AV0 ) _M (1-1) is output to the aperture control circuit 4a, and the setting is made. The image is stopped down to the aperture value. Also, the shutter speed control signal P ₁₀₆ = P ₁₀₀ + P ₁₀₁ − P ₁₀₃ = (BV _aos − AV ₀ ) + SV − (AV − AV ₀ ) _M = TV (1-2) is output to the shutter control circuit 4b. , this value controls the shutter. A display signal P ₁₀₈ =P ₁₀₆ =TV (1-3) is output to the display circuit 6 to display the shutter speed.

When the shutter speed priority mode is selected by the mode information P ₁₀₅ , the diaphragm control signal for the diaphragm control circuit 4a is P ₁₀₇ =P ₁₀₀ +P ₁₀₁ −P ₁₀₄ =(BV _aos −AV ₀ )+SV−TV _M =(AV- _AV0 ) (1-4) is output, and the aperture is controlled according to this value. Further, a shutter control signal P ₁₀₆ =P ₁₀₄ =TV _M (1-5) is output to the shutter control circuit 4b, and the shutter speed is controlled at the set shutter speed. The display signal _P108 = _P102 + _P107 = _AV0 +(AV- _AV0 )=AV (1-6) is outputted to the display circuit 6 to display the control aperture value.

FIG. 4 is a block diagram of a multi-photometering device in which the present invention is applied to the circuit of FIG. 3, and a correction calculation circuit and a correction value calculation circuit 8 are added compared to FIG. The correction value calculation circuit 8 receives the aperture control signal P ₁₀₇ =AV−AV ₀ from the apex calculation unit 3, the open aperture diameter information P ₁₀₂ =AV ₀ input from the information setting unit 5, and the characteristics due to the optical system of the lens. Correction values δ _{11 ...δ ij ...δ 46 corresponding to the photoelectric outputs P 11 ...P ij ... P 46 at} the respective positions are calculated based on the signal P ₁₀₉ =L shown. Written as a general formula, δ _ij can be found as δ _ij = f _ij (AV−AV ₀ , AV ₀ , L) (2). This formula can be determined by experiment.

The correction calculation circuit 7 uses the outputs P ₁₁ ,...P _ij of the photometry circuit 1
…P ₄₆ and the output of each of the outputs δ ₁₁ …δ _ij …δ ₄₆ of the correction value calculation circuit 8 are added P ₁₁ +δ ₁₁ ,…, P _ij +δ _ij ,…,
It consists of adder circuits ₇₁₁ ,... _7ij ,... ₇₄₆ that perform _P46 + _δ46 .

The photovoltage power of the photometric circuit The output of the correction value calculation circuit is When expressed in matrix form, the correction calculation circuit 8
teeth, This means that we are performing matrix operations. Here, B′ _ij −AV ₀ means the photoelectric output after correction.
In the end, the photoelectric output corrected from the correction calculation circuit 7
P ₁₁₁ = BV ₁₁ ′−AV ₀ ,…P ₁₄₆ = BV′ ₄₆ −AV ₀ is input to the multi-photometry processing circuit 2, where the appropriate exposure value is determined.
P ₁₀₀ ′=BV′ _aos −AV ₀ is calculated. This value is more accurate because it is based on corrected photoelectric output. The following sequence is similar to that in FIG.

Next, we will discuss what kind of correction is actually required.

FIG. 5 is an example of a case where a uniform brightness surface is photographed using lenses having the same focal length and different open aperture values. The horizontal axis represents the position with O being the center of the screen, and the vertical axis represents the photoelectric output in FIG. 5a, the film surface illuminance in FIG. 5b, and the correction value in FIG. 5c. Let us consider, as an example, a lens with an open aperture of f/1.4 and a lens with an open aperture of f/2.8 in FIG. 5a. Naturally, the photoelectric power is larger when photometry is performed with an f/1.4 lens, but the photoelectric output in the peripheral area is considerably lower due to vignetting, which is particularly noticeable with large-diameter lenses. On the other hand, when photographing with both lenses apertured to f/8, the illuminance distribution on the film surface becomes almost flat in either case, as shown in FIG. 5b. That is, in multi-photometry processing, the distribution shown in FIG. 5a must be converted into the distribution shown in FIG. 5b before processing.

To solve this problem, first decide on a reference lens (for example, f/2.8), and then calculate the difference between the photoelectric output and the film surface illumination output for that reference lens.
That is, the difference between a and b in FIG. 5 is determined. This difference becomes the reference amount. Next, in order to correct the difference due to the open aperture value, the difference in photoelectric output between the two lenses is determined in FIG. 5a. Then, as shown in FIG. 5c, a correction value distribution is obtained in which a large correction value is added to the output power on the peripheral side of the screen for a large-diameter lens. However, the fact that the area near the center in FIG. 5c is not O indicates that the relationship between the photoelectric output and the film surface illuminance is not according to the nominal step difference in the open aperture value even in the center area.

Now, this correction is applied by determining the size of the peripheral aperture value information P ₁₀₂ =AV ₀ from the information setting section 5 in FIG. 4. If the lens has a large aperture, the amount of correction on the peripheral side will be large.

FIG. 6 shows a photoelectric output distribution, b film surface illuminance distribution, and c correction value distribution when photographing a uniform brightness surface with the same lens by changing the aperture. The horizontal axis represents the position within the screen as in FIG. Since the lenses are the same, the distribution of photoelectric output during open photometry is determined to be the same as shown in FIG. 6a. However, when actually photographing, the effect of vignetting differs depending on the aperture value used. Particularly near the aperture, the illuminance distribution on the film surface decreases at the periphery of the screen as shown in Figure 6b.
become bigger like. Normally, we often shoot with the aperture stopped down to a certain small aperture value or less, so if we use this small aperture value as a reference and shoot with the lens close to its maximum aperture, we will reduce the photoelectric output at the periphery of the screen as shown in Figure 6c. corrections must be made.

This correction is applied by determining the magnitude of the aperture control signal P ₁₀₇ =AV-AV ₀ from the apex calculation unit 3 in FIG.

FIG. 7 shows a photoelectric output distribution, b film surface illuminance distribution, and c correction value distribution when a uniform brightness surface is photographed at the same aperture value using lenses with different optical systems at the same open aperture value. The horizontal axis represents the position within the screen as in FIG. In the photoelectric output distribution in the open state of the lens, there is not much difference between the lens with a long illumination distance and the reference lens as shown in FIG. 7a. However, with respect to the film surface illuminance distribution when stopped down, the reference lens has a considerably lower film surface illuminance at the periphery due to the cosine fourth law, whereas the lens with a long illumination distance has a fairly flat film surface illuminance distribution ( Figure 7 b).

Therefore, for such a lens, when the aperture is not wide open, the photoelectric output at the periphery of the screen is expressed as a in Figure 7.
The difference between and b must be corrected to the positive side (Figure 7c). Application of this correction is determined based on a signal P ₁₀₉ =L from the information setting unit 5 that indicates characteristics specific to the lens. The amount of correction that cannot be expressed by AV ₀ (=P ₁₀₁ ) or AV−AV ₀ (=P ₁₀₇ ) is expressed by this signal L=P ₁₀₉
The correction value calculation circuit 8 is caused to calculate the correction value (according to the focal length and exit pupil distance of the lens, for example).

If we simply consider photometry, the signal L (=
P ₁₀₉ ), it is sufficient to transmit the photometric correction amount of the lens, but if various types of automation are considered in the camera, a considerable number of signals will be required. The applicants of the present invention have focused on this point and have confirmed that the correction objective can be almost achieved by using signals according to the size of the focal length. L = (P ₁₀₉ )
It is advantageous to use this as a focal length signal because it can be used for purposes other than photometry.

In the embodiments described above, the light receiving element P ₁₁
When dividing the screen into 24 parts of 4×6 by P ₄₆ , the number of correction values that must be calculated is 24, δ ₁₁ to δ ₄₆ . However, since the imaging characteristics of the lenses are the same on concentric circles centered on the optical axis, it can be considered that portions equidistant from the center have the same amount of correction. Therefore, if the photometric system is considered to have the same photometric characteristics on a concentric circle centered on the optical axis of the photographing lens, the amount of correction will be as shown in Figure 8. and δ ₀ ... δ ₄ . Also, during this period, as can be seen from Figures 5c, 6c, and 7c, δ ₀ ≧δ ₁ ≧δ ₂ ≧δ ₃ ≧δ ₄ or δ ₀ ≧δ ₁ ≧δ ₂ ≧ ₃ δ ₄ ( It is also worth noting that 7) holds true. However, if the photometric system has photometric characteristics that are symmetrical only horizontally with respect to the screen, the representative correction values will also be symmetrical horizontally and asymmetrical vertically.

FIG. 9 shows a simplified version of the embodiment shown in FIG. 4 by utilizing the above features. The correction value calculation circuit 8 receives the aperture diameter information AV ₀ (=P ₁₀₂ ) from the aperture control signal information setting unit 5 from the apex calculation unit 3 and the lens signal L.
(=P ₁₀₉ ), the correction values δ ₀ , δ ₁ , ... δ ₄ are calculated.

In the correction calculation circuit 7, P ₂₃ , P ₂₄ , P ₃₃ , P ₃₄
δ ₀ is P ₁₃ , P ₁₄ , P ₂₂ , P ₂₅ , P ₃₂ , P ₃₅ , P ₄₄ ,
P ₄₄ has δ ₁ , P ₁₂ , P ₁₅ , P ₄₂ , P ₄₅ has δ ₂ , P ₂₁ ,
P ₂₆ , P ₃₁ , P ₃₆ have δ ₃ , and P ₁₁ , P ₁₆ , P ₄₁ ,
δ ₄ is added to P ₄₆ , respectively.

Note that the information transmitted from the lens to the information setting section 5
AV ₀ , AV−AV ₀ , and L can be determined using mechanical transmission means such as pins installed in the lens barrel or aperture ring, or electrical signal generation means installed inside the lens barrel. All you have to do is communicate it. Since both methods are well known, their explanations will be omitted here.

FIG. 10 shows a more detailed embodiment of the present invention. 1 is a photometric circuit, which is made up of an OP amplifier OP _ij , a photodiode PD _ij , and a logarithmic compression diode LD _ij as one photometric block, which are assembled as many times as the number of divisions. The common mode input of the OP amplifier OP _ij has a reference bias of E ₀ . The photometric current IL _ij generated in the photodiode PD _ij is logarithmically compressed by the logarithmic compression diode LD _ij , and the output becomes V(P _ij )=E ₀ +kT/qInIL _ij /IS (8).

Reference numeral 8 denotes a correction value calculation circuit which receives an aperture control signal P ₁₀₇ =AV-AV ₀ from the apex calculation circuit and receives open aperture diameter information P ₁₀₂ =AV ₀ and lens signal P ₁₀₉ =L from the information setting section 5.

AV ₀ is input to the comparator C1, AV-AV ₀ is input to the comparator C2, and the signal L is input to the in-phase input terminal of the comparator C3. Resistance R15, R1
A current I ₀ flows from a constant current source I ₀ to the inverting input terminal of the comparators C1 and C3, and I ₀ (R15
+R16) and the voltage I ₀ R ₁₆ is applied to the inverting input terminal of the comparator C2. Comparator C1 outputs a logic value "1" when AJ ₀ ≧AV ₀ th (=I ₀ (R ₁₅ + R ₁₆ )) (9). Comparator C2 is (AV−AV ₀ )≧(AV−AV ₀ )
When th(=I ₀ R ₁₆ ) (10), the output becomes 1 and is inverted by the inverting circuit NOT. Comparator C3 outputs “1” when L≧Lth(=I ₀ (R ₁₅ + R ₁₆ ) (11), and comparator C2,
When both outputs of C3 are “1”, NAND circuit
The output of NAND becomes a logical value "0".

In other words, when the lens has an open aperture value below a certain value (AV ₀ )th, the output of comparator C1 is "0", and the number of stops is below a certain value (AV - AV ₀ )th. That is, when correction near the open aperture is required, the NOT output from the NOT circuit becomes "1".

Further, if the signal L is a focal length signal, the output of the NAND circuit NAND will be "0" when the focal length is greater than a certain value and the aperture is not near its maximum opening, that is, when correction is required due to the difference in lenses.

A reference voltage E ₀ is applied between the base and emitter of the transistor TR3 and between the resistor R14,
The collector current of transistor TR3 is constant. Therefore, the voltage across the resistor R13 is constant. Let this voltage be E1.

Therefore, a voltage E1 lower than Vc.c. is applied to the common-mode input terminals of the OP amplifiers OP1 and OP2. The output terminals of the OP amplifiers OP1 and OP2 are connected to the bases of the transistors TR1 and TR2, and the emitters are connected to the inverting input terminals, respectively. A resistor R7 and a series connection of resistor R8 and FET1 are connected in parallel between the emitter of the transistor TR1 and Vc.c., and a resistor R1 is connected between the collector of the transistor TR1 and GND.
is connected. Similarly, a resistor R10 and FET2 are connected between the emitter of transistor TR2 and Vc.c.
The series connection circuits of R11 and FET3, R12 and FET4, and the resistor R9 are respectively connected in parallel. collector of transistor TR2 and
A resistor R2 is connected between GND.

Due to the characteristics of the OP amplifier, the voltage between the emitters of transistors TR1 and TR2 and Vc.c. is always E1.
is maintained. Now, when no correction is performed, the output of comparator C1 is “1” and FET1 is ON.
become a state. Therefore, the emitter current of transistor TR1 is (E ₁ /R ₇ +E ₁ /R ₈ ), and if h _fe is high, it becomes equal to the collector current, so if the voltage across R ₁ is expressed as V (R1), then V (R1) =V(R1)normal= _R1 (1/ _R7 +1/ _R8 ) _E1
...No correction (12), and this voltage becomes the bias voltage applied to the photoelectric output in the center when no correction is made. On the other hand, when the output of comparator C1 becomes "0" in the case of a large-diameter lens, FET1 turns OFF, and transistor TR1
The collector current of is only E ₁ /R ₇ . That is, V(R ₁ )=R ₁ /R ₇ E ₁ =V(R1)normal−R ₁ /R ₈ E ₁ =V
(R1) normal−V _{fp cpnp1} at the time of large aperture correction (13), and the second term is the correction term for the central portion at the time of large aperture.

On the other hand, when there is no correction regarding the peripheral area,
In addition to the output of comparator C1 being “1”,
The output of NOT is “0”, the output of NAND is “1”,
FET2 and FET4 are in ON state and FET3 is
It is in the OFF state.

Therefore, the collector current of transistor TR2 is (1/R ₉ + 1/R ₁₀ + 1/R ₁₂ )E ₁ and resistor R2
If the voltage across both ends is V(R2), then V(R2)=V(R2)normal=R ₂ (1/R ₉ +1/R ₁₀ +
1/R ₁₂ )E ₁ ...no correction (14), and this voltage becomes the peripheral bias voltage when no correction is made. When correcting a large aperture lens, the output of comparator C1 becomes “0” and the FET
2 is OFF, V(R2) = R ₂ (1/R ₉ + 1/R ₁₂ ) E ₁ = V(R2) norma
l−R ₂ /R ₁₀ E ₁ = V(R2)normal −V _fp,COnp2 ...at the time of large aperture correction (15), and the second term is the correction term for the peripheral part at the time of large aperture.

When correcting when open, NOT output is “1”
Then, FET3 turns on, V(R2)=R ₂ (1/R ₉ +1/R ₁₀ +1/R ₁₁ +1/R ₁₂
) E ₁ = V (R2) normal + R ₂ / R ₁₁ E ₁ = V (R2) normal + V _{f-fp, cpnp} when correcting the aperture (16), and the second term is the correction term when the aperture is open, and it is the correction term for the peripheral area of the screen. It is joining only.

When correction is required due to a difference in the optical system of the lens, the output of NANDA becomes “0” and FET4
OFF, V(R2) = R ₂ (1/R ₉ + 1/R ₁₀ ) E ₁ = V(R2) norma
l−R ₂ /R ₁₂ E ₁ V (R ₂ ) normal −V _L,cpnp ...when correcting the optical system (17), and the second term is the correction term due to the difference in lenses. This also applies only to the periphery of the screen.

OP amplifiers OP3 and OP4 constitute a voltage follower circuit, and the input V(R1), V(R2)
will be output as is.

Resistors R3, R4, R5, and R6 are connected in series between the output terminals of the OP amplifiers OP3 and OP4. The respective terminal voltages are V(δ ₀ ), V(δ ₁ ),
...V(δ ₄ ), the following equation is obtained.

V(δ ₀ )=V(R1) (18) V(δ ₁ )=V(R1)+R ₃ /R ₃ +R ₄ +R ₅ +R ₆ {V(R2
)−V(R1)}(19) V(δ ₂ )=V(R1)+R ₃ +R ₄ /R ₃ +R ₄ +R ₅ +R ₆ {V
(R2)−V(R1)}(20) V(δ ₃ )=V(R1)R ₃ +R ₄ +R ₅ /R ₃ +R ₄ +R ₅ +R ₆ {
V(R2)-V(R1)}(21) V(δ ₄ )=V(R2) (22) This V(δ ₀ )...V(δ ₄ ) is δ ₀ ...δ in the block diagram of FIG. This is the output of the correction value calculation circuit corresponding to ₄ .
FIG. 11 is a diagram in which the horizontal axis represents the distance from the center of the screen and the vertical axis represents the correction value δ. As is clear from this figure, the correction value δ changes in a curved manner. Depending on the content of the correction, it changes in various ways as shown by the curve shown by the dotted line. However, when k ₁ , k ₂ , and k ₃ are constants, δ ₁ − δ ₀ : δ ₂ − δ ₀ : δ ₃ − δ ₀
: δ ₄ − δ ₀ = k ₁ : k ₂ : k ₃ : 1 (23) The following relationship almost always holds true. Therefore, R ₃ / (R ₃ + R ₄ + R ₅ + R ₆ ) = k ₁ (24) (R ₃ + R ₄ ) / R ₃ + R ₄ + R ₅ + R ₆ ) = k ₂ (25) (R ₃ + R ₄ + R ₅ )
/ (R ₃ + R ₄ + R ₅ + R ₆ ) = k ₃ (26), then V (δ ₀ ) = V (R1) (18) V (δi) = V (R1) + ki {V (R2)
−V(R1)}(i=1.2.3)(27) V(δ ₄ )=V(R2) (22) The above correction can be performed.

Now, returning to Figure 10, 7 is a correction calculation circuit, and each block (723, 734, etc.) is one block.
It consists of an OP amplifier (OP1ij), one transistor (Tr1ij), and two resistors (R1ij, R2ij). The calculation for the photoelectric output P23 will be explained below as an example. When the output V (δ ₀ ) of the correction value calculation circuit 8 is applied to the in-phase input terminal of the OP amplifier OP123, the emitter potential of the transistor TR123 becomes V (δ ₀ ). On the other hand, the output V (P23) of the OP amplifier OP23 of the photometry circuit 1 is connected to the other end of the resistor R123.
is being applied. Therefore, the current flowing through the resistor R123 is {V(δ ₀ )−V(P23)}/R123, and if h _fe of the transistor TR123 is high, the emitter current≈collector current is equal to the current flowing through the resistor R223. Therefore, if R123=R223, the voltage V23 across the resistor R223 becomes V23=V(δ ₀ )−V(P23) (28). Similarly, V ₂₄ = V (δ ₀ ) − V (P24) (29) V ₃₃ = V (δ ₀ ) − V (P33) (30) V ₃₄ = V (δ ₀ ) − V (P34) (31 ) V ₁₃ = V (δ ₁ ) − V (P13) (32) 〓 〓 V ₄₆ = V (δ ₄ ) − V (P46) (33). This has the opposite sign from equation (5), but this is due to the circuit structure.

Next, the actual method of correction will be described.

First, if there is no need for correction, equations (12) and (14) hold, and V (δ ₀ ) = V (R1) normal (34) V (δ ₄ ) = V (R2) normal (35), but The two are not necessarily equal. This is because V(R1)normal and V(R2)normal can contain a considerable part of the term for the initial shift of the photoelectric output. Dark current and temperature compensation terms can also be added. At this time, the other parts are also obtained from equation (28): V(δi)=V(R1)normal+k _i {V(R1)normal−
V(R2)normal} (i=1,2,3) (36) However, the changes are gradual and cannot be predicted. These outputs are input to the correction calculation circuit 7 together with the photometric output V (Pij). The output of the correction calculation circuit is V ₂₃ V (R1) normal - V (P23) (37) V ₁₃ = V (R1) normal + k ₁ {V (R2) normal - V (R1
)normal}−V(P13)(38) 〓 V ₄₆ =V(R2)normal−V(P46) (39).

When correction of the large aperture lens is now required, the correction value calculation circuit 8 detects this using the comparator C1, and produces outputs according to equations (13) and (15).

That is, V(δ ₀ )=V(R1)normal−V _{fp cpnp1} (40)
V(δi)=V(R1)normal+k _i {V(R2)normal−
V (R1) normal} −V _fp,cpnp1 −K _i (V _{fp cpnp2} −V _{fp cpnp1} ) (i=
1, 2, 3) (41) V(δ ₄ )=V(R2)normal−V _{fp cpnp2} (42) is obtained. The output of the correction calculation circuit 7 is V ₂₃ =V(R1)normal−V(P23)−V _{fp cpnp1} (
43) V ₁₃ = V (R1) normal + k ₁ {V (R2) normal - V (R1
)normal} −V(P13)−V _{fp cpnp1} −k ₁ (V _{fp cpnp2} −V _{fp cpn
p1} })(44) 〓 V ₄₆ =V(R2)normal−V(P46)−V _{fp cpnp2} (45)
becomes. If the bias term is removed, the corrected raw and V(P23)←→V(P23)+V _{fp cpnp1} (46) V(P13)Z←→V(P13)+(1−k ₁ )V _{fp cpnp1} +k
₁ V _{fp cpnp2} (47) There is a correspondence relationship of V (P46)←→V (P46) + V _{fp cpnp2} (48). Here, the second term and subsequent terms on the right side are correction terms for each part. V _{fp cpnp1} is a correction term that was also used in the center-weighted photometry method, which is a conventional photometry method using a single photoelectric output, and is intended to compensate for the decrease in central spectral photoelectric output when using a large aperture lens. The value is large because it corrects the photoelectric output at the part that is the farthest away. (See Figure 5c).
Also, intermediate correction values are added to intermediate positions, and the values increase as you move toward the periphery. In the manner described above, the corrected photoelectric output information is transmitted to the multi-photometry processing circuit 2.

Now, let's consider the case where correction is made when the lens is opened. When the aperture is close to open, comparator C
2 and NOT, and the output of the correction value calculation circuit 8 becomes a value based on equations (12) and (16). That is, V(δ ₀ )=V(R1)normal (34) V(δi)=V(R1)normal+k _i {V(R2)normal−
V(R1)normal} +k _i V _f-fp,cpnp (i=1,2,3) (49) V(δ ₄ )=V(R2)normal+V _f-fp,cpnp (50) is obtained. Therefore, the output of the correction calculation circuit 7 is V ₂₃ = V (R1) normal - V (P23) (37) V ₁₃ = V (R1) normal + k ₁ {V (R2) normal - V (R1
)normal} -V(P13)+k ₁ V _f-fp,cpnp (i=1,2,3)(51
) V ₄₆ = V (R2) normal - V (P46) + V _{f-fp cpnp} (52)
becomes. If the bias term is excluded, the difference between before correction and V(P23)←→V(P23) (53) V(P13)←→V(P13)−k ₁ V _f-fp,cpnp (54) V(P46)←→ There is a correspondence relationship of V(P46)−V _f-fp,cpnp (55). The photoelectric output at the center of the screen remains the same, but the correction value decreases as you move toward the periphery of the screen. That is, the correction shown in FIG. 6c is performed.

Finally, we will discuss corrections due to differences in lens optical systems. In the case of a lens that requires correction, it is detected by comparator C3, and if the aperture is not close to its maximum opening, it is detected by comparator C2, and when both conditions are satisfied, it is detected as a state requiring correction by NAND output. Ru. At this time, the correction value calculation circuit 8 outputs values based on equations (12) and (17). That is, V(δ ₀ )=V(R1)normal (34) V(δi)=V(R1)normal+k _i {V(R2)nor
mal−V(R1)normal} −k _i V _L,cpnp (i=1,2,3) (56) V(δ ₄ )=V(R2)normal−V _L,cpnp (57)
get. Therefore, the output of the correction calculation circuit is V ₂₃ = V (R1) normal - V (P23) (37) V ₁₃ = V (R1) normal + k ₁ {V (R2) normal -
V(R1)normal} −V(P13)−k ₁ V _L,cpnp (i=1,2,3)
(58) V ₄₆ = V (R2) normal - V (P46) - V _L,cpnp (59
) becomes. If the bias term is excluded, the difference between before correction and V(P23)←→V(P23) (53) V(P13)←→V(P13)＋k ₁ V _L,cpnp (60) V(P46)←→V(P46 ) + V _L,cpnp (61). Although the photoelectric output at the center of the screen remains the same, the amount of correction added increases toward the periphery of the screen. That is, the correction shown in FIG. 7c is performed.

Above, each correction was explained independently, but
When shooting with a large aperture lens wide open, the following relationship will occur: That is, V(P23)←→V(P23)＋V _fp,cpnp1 (46)
V(P13)←→V(P13)+(1− _k1 )V _{fp cpnp1}
+k ₁ V _{fp cpnp2} −k ₁ V _{f-fp cpnp} (61) V(46)←→V(P46)＋V _{fp cpnp2} −V _{f-fp cp}
It works in the direction of cancellation like _np (62). This means that using a lens with a strong influence of vignetting near its maximum aperture is equivalent to using a normal lens at a normal aperture.

In the above explanation, the various information input from the apex calculation section 3 and the information setting section 5 to the correction value calculation circuit 8 were classified into two, each with one reference level, but by increasing the reference level, , correction with fewer errors becomes possible.

FIG. 12 shows an example of a receiving optical system. 331 is a plurality of photoelectric elements shown in FIG. 1; 332 is a photographing lens; 333 is a mirror; 334 is a film surface; 335 is a finder screen; This is a lens for re-imaging.

With the above configuration, the brightness of each part of the scene to be photographed can be measured, and a plurality of independent photometric information can be extracted. In the explanation so far, we have focused on wide-open photometry, but photometry errors for the same reason exist especially in the periphery of the screen even in stop-down photometry. The present invention is also effective in correcting this.

In the embodiment, the aperture calculation section 3 controls the aperture control circuit 4a and the correction value calculation circuit 8 using the same aperture control signal (AV-AV ₀ ), but it is not necessary that they are the same. There isn't. That is,
This is because information on whether the aperture is close to the open aperture may be transmitted to the correction value calculation circuit 8, and the aperture control circuit 4a may be controlled using different information depending on the control method. For example, in the case of a system in which the aperture is stopped when the light amount (BV-AV) reaches a certain value while monitoring the light amount after release, the signal sent to the aperture control circuit is TV-SV. In other words, it is appropriate when BV−AV≡TV−SV (62) holds.

According to the present invention, photometry errors in multi-photometry etc. caused by lens characteristics (in the embodiment, expressed by the open aperture value, focal length, etc.) and the aperture value, etc., especially photometry errors in the peripheral area of the screen. This has the advantage of being able to sufficiently correct for practical purposes. Further, even if the aperture is narrowed down to the minimum aperture, it is possible to detect and correct the case where the aperture is controlled to be opened. By performing these corrections, the results of multi-photometry processing etc. become closer to the appropriate exposure value.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of screen division, Figure 2a is a diagram showing photoelectric output distribution, Figure 2b is a diagram showing film surface illuminance distribution, Figure 3 is a block diagram of a conventional multi-photometer, and Figure 3 is a diagram showing a photoelectric output distribution. Figure 4 is a block diagram of the multi-photometering device according to the present invention, Figure 5 is a diagram showing that correction is required based on the open aperture diameter, Figure 6 is a diagram showing that correction is required based on the shooting aperture diameter, and Figure 7 is a diagram showing the necessity of correction based on the shooting aperture diameter. is a diagram showing that correction is required due to differences in the optical system of lenses, FIG. 8 is a diagram showing how to summarize correction values, FIG. 9 is another block diagram of the multi-photometering device according to the present invention, and FIG. 10 is a diagram showing how to summarize correction values. More detailed diagram of the photometry circuit, correction value calculation circuit, and correction calculation circuit of the multi-photometering device according to the present invention, 1st
FIG. 1 is a diagram showing a correction value curve, and FIG. 12 is a diagram showing an example of a receiving optical system. Explanation of the symbols of the main parts: Photometric means...1, Calculation means...2, 3, Correction information output means...8, Correction means...7.

Claims (1)

[Scope of Claims] 1. Receives light passing through an aperture in an open state, divides the central area of the field screen and peripheral areas around it, and measures the light to generate a plurality of photometric outputs corresponding to each area. a calculation means for calculating an appropriate exposure according to the state of the subject based on the plurality of photometry outputs and determining an aperture value to be controlled to obtain the appropriate exposure; and characteristics of the lens used. output means for outputting a signal related to the aperture value to be controlled by the arithmetic means, and a signal related to the lens characteristics of the output means, for each of the central region and the peripheral region, from an open aperture state to correction information output means for outputting information regarding a predicted change in light amount when the aperture is controlled to the aperture value to be controlled; and applying corresponding outputs of the correction information output means to the plurality of photometric outputs, respectively; and a correction means for correcting each of the plurality of photometric outputs so as to correspond to a state in which the aperture is controlled, and transmitting the corrected values to the calculation means, and the calculation means calculates the field of view based on the output of the correction means. A multi-photometering device that calculates the appropriate exposure according to the situation and determines the exposure amount. 2. The multi-photometering device according to claim 1, wherein the signal related to the characteristics of the lens is a signal that changes depending on the open aperture value and/or focal length of the lens. Multi-photometering device. 3. The multi-photometering device according to claim 1, wherein the peripheral area is divided into a plurality of areas, and the photometric means generates photometric outputs for each of the central area and the plurality of peripheral areas. Multi-photometering device.