JPH058589Y2 - - Google Patents

Description

[Detailed description of the invention] This invention measures the light by dividing the field into multiple areas, and determines the appropriate exposure of the entire screen from multiple photoelectric outputs corresponding to each of the multiple areas. The present invention relates to a correction device for a multi-photometering device that calculates and extracts output.

Various such multi-photometering devices have been proposed. An 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 actual shooting aperture value.
It was impossible to ignore. Furthermore, even if the light-receiving surface of multi-photometering is located at a position substantially coextensive with the film surface, this phenomenon is unavoidable because a light-receiving optical system is interposed in the former.

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 so affected by the difference in , 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 also consider the case where the screen is divided into a 4×6 matrix and photometry is performed. When the brightness plane is uniform from the subject, part A- on the screen in Figure 1
The photoelectric output at A' shows 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.

This drawback has not been solved in the multi-photometering devices proposed so far.

An object of the present invention is to solve these drawbacks and provide a multi-photometering device with less exposure error by correcting the obtained photoelectric output so that it approaches the illuminance of the film surface.

FIG. 3 is a block diagram showing the basic configuration of the multi-photometering device, 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,
4 is a shutter control circuit, 5 is an information setting section, and 6 is a display circuit. When the photometry circuit 1 is divided as shown in Fig. 1, photoelectric outputs P ₁₁ (=BV ₁₁ −AV ₀ ; the same applies hereinafter because of TTL open photometry) correspond to each position, P ₁₂ (=BV ₁₂ −AV ₀ ),…, P ₄₆
(=BV ₄₆ −AV ₀ ) is obtained. Note that the number of each light receiving element and the number of each photoelectric output are the same in order to clarify the correspondence. This output is input to the multi-photometering processing circuit 2, where it performs a series of arithmetic processing and produces one arithmetic output P ₁₀₀ = BV _aos − as an estimated value of appropriate exposure.
Calculate AV ₀ . An example is JP-A-52-
12828, and Japanese Patent Application No. 54-23019 (Japanese Unexamined Patent Publication No. 55-114918) and Japanese Patent Application No. 54-23020 (Unexamined Japanese Patent Application No. 55-1989) filed by the applicant.
114916) etc. The apex calculation circuit 3 receives film sensitivity information P ₁₀₁ =SV from the information setting section 5;
Aperture information P ₁₀₂ = (AV−AV ₀ ) and calculation output related to brightness calculated by the multi-photometry processing circuit 2 P ₁₀₀ =
BV _aos −AV ₀ is input and the next apex operation is performed.

(BV _aos - AV ₀ ) + SV - (AV - AV ₀ ) = BV _aos + SV - AV = TV (= P ₁₀₃ ) (1) The TV value obtained as a result is the shutter control circuit 4.
input to control shutter speed. It is also input to the display circuit 6 to display the shutter speed.

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 7 and a correction value calculation circuit 8 are added compared to FIG. The correction value calculation circuit 8 receives the open aperture diameter information P ₁₀₅ =AV ₀ and the aperture stage number information input from the information setting section.
Correction value δ ₁₁ ... corresponding to the photoelectric output P ₁₁ ...P _ij ...P ₄₆ at each position according to P ₁₀₂ = AV - AV ₀ and signal P ₁₀₆ = L indicating characteristics caused by the optical system of the lens.
Calculate δ _ij ...δ ₄₆ . Written as a general formula, δ _ij can be found as δ _ij =f(AV ₀ , AV−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 , ...,
Addition circuit that performs P ₄₆ + δ ₄₆ 7 ₁₁ ,..., 7 _ij ,..., 7
It is established from ₄₆ .

The photoelectric output 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 corrected photoelectric output from the correction calculation circuit 7
P ₁₁₁ =BV ₁₁ ′−AV ₀ , . . . P ₁₄₆ =BV′ ₄₆ −AV ₀ are input to the multi-photometry processing circuit 2, where the appropriate exposure value 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 the center of the screen as 0, and the vertical axis represents FIG. 5a: photoelectric output, FIG. 5b: film surface illuminance, and FIG. 5c: correction value. 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 both cases, 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). The difference between the photoelectric output and the film surface illuminance 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 photoelectric output 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 0 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 open aperture value information P ₁₀₅ =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 opening, the film surface illuminance distribution drops significantly at the periphery of the screen, as shown in FIG. 6b. 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 to the information setting section 5 in FIG.
This is done by determining the size of the narrowing down stage number information _P102 =AV− _AV0 from P102=AV−AV0.

FIG. 7 shows a photoelectric output distribution, b film surface illuminance distribution, and c correction 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 focal length (focal length 105 mm) and the reference lens (focal length 50 mm) 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 in the peripheral area due to the cosine fourth law, whereas a lens with a long focal length has a fairly flat film surface illuminance distribution ( Figure 7 b). Note that FIG. 7b shows a state where the aperture is stopped down to about f/8.

Therefore, for such a lens, when the aperture is not fully open, the photoelectric output at the periphery of the screen must be corrected to the plus side by the difference between a and b in FIG. 7 (FIG. 7c). This correction is applied to the information setting section 5.
The determination is made based on the signal P ₁₀₆ =L indicating the characteristic peculiar to the lens. AV ₀ (=P ₁₀₅ ) or AV−AV ₀ (P ₁₀₂ )
This signal L=
P ₁₀₆ (according to, for example, the focal length and exit pupil distance of the lens), the correction value calculation circuit 8 is caused to calculate it.

If we simply consider photometry, the signal L (=
P ₁₀₆ ), 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 ₁₀₆ )
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 elements P ₁₁ ~
When dividing the screen into 24 4×6 pixels using P ₄₆ , the number of correction values that must be calculated is 24 from δ ₁₁ to δ ₄₆ . However, since the imaging characteristics of the lenses are the same on concentric circles centered on the optical axis, the amounts of correction can be considered to be the same for portions equidistant from the center. Therefore, if the photometric system can be considered to have the same photometric characteristics on a concentric circle centered on the optical axis of the photographing lens, the correction value should be
As shown, and δ ₀ ... δ ₄ . Also, 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 ≦δ 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 characteristics. The correction value calculation circuit 8 receives the open aperture diameter information AV ₀ (=P ₁₀₅ ), the aperture step number information AV−AV ₀ (=P ₁₀₂ ), and the lens signal L (=
P ₁₀₆ ), 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
has δ ₀ , P ₂₂ , P ₂₅ , P ₃₂ , P ₃₅ has δ ₁ , P ₁₃ ,
P ₁₄ , P ₂₂ , P ₂₅ , P ₃₂ , P ₃₅ , P ₄₃ , and P ₄₄ have δ ₁ ,
P ₁₂ , P ₁₅ , P ₄₂ , P ₄₅ have δ ₂ , P ₂₁ , P ₂₆ , P ₃₁ ,
δ ₃ is added to P ₃₆ , and δ ₄ is added to P ₁₁ , P ₁₆ , P ₄₁ , and 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. A reference bias of E ₀ is applied to the common mode input of the OP amplifier OP _ij . 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/qlnIL _ij /I _s (8).

Reference numeral 8 denotes a correction value calculation circuit, which receives open aperture diameter information P ₁₀₅ =AV ₀ and aperture stage number information P ₁₀₂ =AV− from the information setting unit 5.
AV ₀ and lens signal L are received.

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. A current I ₀ flows through resistors R15 and R16 from a constant current source I ₀ , and the converter
The voltage of I ₀ (R15 + R16) is applied to the inverting input terminals of C1 and C3, and the voltage of I ₀ is applied to the inverting input terminal of comparator C2.
The voltage of R16 is applied. Comparator C1 outputs the theoretical value “1” when AV ₀ ≧ AV ₀ th (= I ₀ (R ₁₅ + R ₁₆ ) (9). Comparator
When (AV- _AV0 )≧(AV- _AV0 )th(= _I0R16 ) (10), the output of C2 _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 NAND
The output of is the theoretical value "0".

In other words, when the lens has an aperture value below a certain value (AV ₀ )th, the comparator
The output of C1 becomes "0", and when the number of stages to be stopped down is less than a certain value (AV-AV ₀ )th, that is, when correction is required near the open aperture, the NOT output of 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, and the collector current of the transistor TR3 is constant.
Therefore, the voltage across resistor R13 is constant. Let this voltage be E1.

Therefore, a voltage E1 lower than _Vcc 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 is connected between the emitter of transistor TR1 and _Vcc ,
The series-connected resistor R8 and FET1 are connected in parallel, and the resistor R1 is connected between the collector of the transistor TR1 and GND.
Similarly, resistors R10 and FET2, R11 and FET3, R12 and FET4 are connected between the emitter of transistor TR2 and V _cc .
The respective series connected circuits and the resistor R9 are connected in parallel. transistor tr2
A resistor R2 is connected between the collector of and GND.

Depending on the characteristics of the OP amplifier, transistors TR1 and
The voltage between the emitter of TR2 and _Vcc is always kept at E1. Now, when no correction is performed, the output of comparator C1 is "1" and FET1 is in the ON 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 the voltage V across R ₁
Expressed as (R1), V(R1)=V(R1)normal=R ₁ (1/R ₁ +1/R ₈ )
E ₁ ...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, in the case of a large-diameter lens, when the output of the comparator C1 becomes "0", the FET1 is turned off, and the collector current of the transistor TR1 becomes only _E1 / _R7 . That is, V (R1) = R ₁ / R ₇ E ₁ = V (R1) normal - R ₁ / R ₈ E ₁ (1
3) =V(R1)normal−V _fp,cpnp1 at the time of large aperture correction, and the second term is the correction term for the central portion at the time of large aperture. On the other hand, in a state where there is no correction regarding the peripheral area, the output of comparator C1 is "1", and in addition,
NOT output is “0”, NAND output is “1”
So, FET2 and FET4 are in ON state and FET3 is OFF.
in a state.

Therefore, the collector current of transistor TR2 is (1/R ₉ + 1/R ₁₀ + 1/R ₁₂ )E ₁ , and if the voltage across resistor R2 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 without correction. When correcting a large aperture lens, the output of comparator C1 becomes “0” and FET2 turns OFF, V (R2) = R ₂ (1/R ₉ + 1/R ₁₂ ) E ₁ = V (R2) nor
mal−R ₂ /R ₁₀ E ₁ =V(R2)normal−V _fp,cpnp2 ...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”
Therefore, FET3 is turned on, and V (R2) = R ₂ (1/R ₉ +1/R ₁₀ +1/R ₁₁ +1/R _1
2 ) E ₁ = V (R2) normal + R ₂ / R ₁₁ E ₁ = V (R2) normal + V _f-fp,cpnp ...at the time of aperture correction (16), and the second term is the correction term at the aperture, and is the correction term for the periphery of the screen. It has only been added to the department.

When correction is required due to a difference in the optical system of the lens, the NAND output becomes “0” and FET4 is turned off.
and V(R2)= _R2 (1/ _R9 +1/ _R10 ) _E1 =V(R2)nor
mal- _R2 / _R12E1 =V(R2)normal- _VL,cpnp ...Optical system correction (17) The second _term is a 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) and V (R2)
will be output as is.

A resistor is connected between the output terminals of OP amplifier OP3 and OP4.
R3, R4, R5, and R6 are connected in series. Each terminal voltage is sequentially 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(R
2) −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 in the block diagram of Figure 9. ...This is the output of the correction value calculation circuit corresponding to δ 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
The relationship (23) almost always holds. 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(δ _i )=V(R1)+k _i {V(R2)−V(R1)}(27
) (i=1,2,3) 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.) corresponds to one OP.
Amplifier (OP1 _ij ), 1 transistor (Tr1ij)
and two resistors (R1 _ij , R2 _ij ).
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 photometric circuit 1 is applied to the other end of the resistor R123. Therefore, the current flowing through resistor R123 is {V(δ ₀ )−V
(P23)}/R123, and the transistor TR123
If h _fe is high, emitter current ≒ collector current, which is equal to the current flowing through resistor R223. Sideways
If R123=R223, the voltage V23 across 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 ) becomes. Although the sign is opposite to that of equation (5), this is due to the circuit configuration.

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 it is not necessary to Both are not equal. A significant part of the term for the initial shift of the photoelectric output is expressed as V(R1)
This is because it can be made to have normal V(R2)normal. Dark current and temperature compensation terms can also be added. At this time, the other parts are also obtained from equation (27): V (δ _i ) = V (R1) normal + k _i {V (R2) normal
−V(R1)normal} (i=1,2,3) (36) However, the change is gradual and there is no contradiction. These outputs are input to the correction calculation circuit 7 together with the photometric output V (P _ij ). The output of the correction calculation circuit is becomes.

When correction of the large aperture lens is now required, the correction value calculation circuit 8 detects it using the comparator C1,
(13) produces output according to equations (15). That is, V(δ ₀ )=V(R1)normal−V _fp,cpnp1 (40) V(δ _i )=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. And the output of the correction calculation circuit 7 is becomes. If the bias term is excluded, the difference between before correction and V(P23)←→V(P23)+V _fp,cpnp1 (46) V(P13)←→V(P13)+(1−k ₁ )V _fp,cpnp1 +k ₁
V _fp,cpnp2 (47) V(P46)←→V(P46) V _fp,cpnp2 (48) There is a correspondence relationship. Here, the second term on the right side becomes the correction term for each part below. V _fp,cpnp1 is a correction term that was also used in the center-weighted side beam method, which is a conventional photometry method using a single photoelectric output, and is used to compensate for the decrease in photoelectric output at the center when using a large aperture lens. It is small in value. Since V _fp,cpnp2 is used to correct the photoelectric output at the part farthest from the center of the screen, its value becomes large (see Fig. 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, the comparator
It is detected by C2 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 (δ _i ) = 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, 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 near its maximum opening, it is detected by comparator C2, and when both conditions are satisfied, it is detected as a state that requires 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 (δ _i ) = V (R1) normal + k _i {V (R2) normal
−V(R1)normal}k _i V _L,cpnp (i=1, 2, 3) (56) V(δ ₄ )=V(R2)normal−V _L,cpnp (57) is obtained. 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 )-k1VL _,cpnp =1,2,3) (58) _V46 =V(R2)normal+V(P46) _-VL,cpnp (59). 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) There is a correspondence relationship. 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 has been explained independently, but when shooting with a large aperture lens wide open, the following correspondence relationship occurs. That is, V(P23)←→V(P23)+V _fp,cpnp1 (46) V(P13)←→V(P13)+(1−k ₁ )V _fp,cpnp1 +k ₁
V _fp,cpnp2 −k ₁ V _f-fp,cpnp (61) V(P46)←→V(P46)＋V _fp,cpnp2 −V _f-fp,cpnp (62
), it acts in the direction of cancellation. 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, there was only an example in which the various information input from the information setting unit 5 to the correction value calculation circuit 8 was classified into two categories, each with one reference level. This makes it possible to make corrections.

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.

According to the present invention, there is an advantage that photometry errors in multi-photometry due to lens characteristics and aperture value, etc., especially photometry errors in the peripheral area of the screen, can be sufficiently corrected for practical purposes, and the results of multi-photometry processing are improved. Close to the appropriate exposure value. Further, in the explanation so far, we have focused on aperture photometry, but even in wide-open aperture photometry, photometry errors exist particularly at the periphery of the screen due to the same reason. The present invention is also effective in correcting this.

[Brief explanation of the drawing]

Fig. 1 shows an example of screen division, Fig. 2a shows the photoelectric output distribution, Fig. 2b shows the film surface illuminance distribution, Fig. 3 is a block diagram of a conventional multi-photometer, and Fig. 4 shows the photoelectric output distribution. A block diagram of the multi-photometering device according to the present invention. Fig. 5 shows the need for correction based on the aperture diameter, Fig. 6 shows the need for correction based on the shooting aperture diameter, and Fig. 7 shows the need for correction based on the aperture diameter. A diagram showing the need for correction due to differences in optical systems, Figure 8 is a diagram showing how to summarize correction values, Figure 9 is another block diagram of the multi-photometering device according to the present invention, and Figure 10 is according to the present invention. 11 is a diagram showing a correction value curve, and FIG. 12 is a diagram showing an example of an optical receiving system. Explanation of symbols of main parts, correction value calculation circuit...
8. Correction calculation circuit...7.

Claims (1)

[Claims for Utility Model Registration] 1. Dividing the photographic screen into a central area and a plurality of peripheral areas located around the central area and performing open metering,
first means for obtaining photometric outputs for the central region and the plurality of peripheral regions, respectively;
and a second means for obtaining exposure information output for exposure control or exposure display based on each photometry output regarding the central area and the plurality of peripheral areas output by the means, the multi-photometering device being mounted on a camera. Based on information that changes depending on the focal length of the photographic lens, the system generates representative correction information output independent of the central area of the photographic screen, with respect to a plurality of peripheral areas located at approximately symmetrical positions within the photographic screen. a correction information output means; a correction means for correcting photometric outputs regarding the plurality of peripheral areas located at the substantially symmetrical positions by the representative correction information output so as to correspond to the film surface illuminance after aperture control; The multi-photometering device is characterized in that the second means obtains exposure information output based on a photometry output regarding the central area and a plurality of photometry outputs regarding the peripheral area corrected by the correction means. 2. The multi-photometering device according to claim 1, wherein the correction information output means introduces information regarding the maximum aperture value of the photographic lens from a photographic lens attached to the camera. 3. Utility model registration claim 1, wherein the correction information output means introduces information regarding the number of aperture steps from the maximum aperture value to the photographic aperture value of the photographic lens from the photographic lens attached to the camera. The multi-photometering device described in section. 4. The multi-photometering device according to claim 1, wherein the information that changes depending on the focal length of the photographing lens indicates the focal length of the photographing lens. 5. The multi-photometering device according to claim 1, wherein the information that changes depending on the focal length of the photographic lens indicates an exit pupil distance of the photographic lens.