JPH0428087B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures light by dividing the field into a plurality of regions, and outputs a proper light metering output that provides proper exposure for the entire screen based on the light metering output corresponding to each of the plurality of regions. The present invention relates to a multi-photometering device.

Conventionally, as this type of photometric device, there is one that uses the arithmetic average value of the maximum and minimum values of multiple photoelectric outputs as the appropriate photometric output (Utility Model Publication No. 51-9271), and one that uses the arithmetic average value of the maximum and minimum values of multiple photoelectric outputs as the appropriate photometric output. There is a method in which a photographer manually extracts an intermediate value and uses this intermediate value as an appropriate photometric output (Japanese Patent Laid-Open No. 17725/1983).

However, these conventional devices have the following drawbacks. In other words, in the former case, the exposure is determined by the arithmetic average value, so the main subject may be underexposed or overexposed under special field conditions, such as backlight or when the main subject is on snow. Sometimes I put it away. Furthermore, even in the latter case, it not only requires skill to set the intermediate value to provide proper exposure under the above-mentioned special field conditions, but also the setting operation is manual, which inevitably reduces operability.

An object of the present invention is to provide a multi-photometering device that classifies the brightness of the main light sources present in the photographic screen (object field) and outputs an appropriate photometering output according to this classification, in order to eliminate these drawbacks. .

FIG. 1 shows an example of a light-receiving element used in the present invention. The light-receiving element 1 has a 4×6 matrix, and is capable of photometry with a screen divided into 24 parts.

FIG. 2 shows an example of the light receiving element 1 when the number of divisions is reduced, and it is possible to obtain as photometric outputs PV ₀ at the center of the screen, PV ₁ at the upper left of the screen, PV ₂ at the upper right of the screen, and PV ₄ at the lower right of the screen.

FIG. 3 shows an example of the light receiving element 1, 2 is a lens,
3 is an aperture, 4 is a mirror, 5 is a shutter, 6 is a film image, 7 is a finder optical system, and 8 is a lens for forming a subject image on the light receiving element 1. In this way, the luminance value of each part of the photographic screen can be photometered.

FIG. 4 is a block diagram showing the basic configuration of the present invention. The photometry circuit 10 includes the light receiving device 1 shown in FIG. 4, and has TTL open photometry output PV ₀ ~
Output PV ₄ . These outputs correspond to the brightness BV ₀ to BV ₄ (apex value) of each part of the divided screen.
The light intensity is reduced by the maximum aperture AV ₀ (apex value) of the lens, which is a factor in the reduction in light intensity caused by TTL photometry.

That is, PV ₀ = BV ₀ − AV ₀ PV ₁ = BV ₁ − _{AV 0} 〓 〓 PV ₄ = BV ₄ − _{AV 0} . The brightness calculation unit 11 calculates a plurality of photometric outputs PV _j =BV _j −AV ₀ (where j=0 to
4) and the maximum aperture value of the lens from the information setting circuit 50.
Introducing AV ₀ and adding these to each absolute brightness BV _j
get. Maximum value output circuit 12, average value output circuit 1
3. The minimum value output circuit 14 receives the output of the brightness calculation circuit 11, and outputs the maximum value BVmax and the average value.
Output BVmean and minimum value BVmin. Comparison circuits 51 to 53 are the outputs of the maximum value output circuit 12
It inputs _BVmax and selectively generates a logic "1" output depending on the level of _BVmax . For example, the comparison circuit 51 outputs “1” when BVmax _x ≧9,
Comparison circuit 52 is “1” when 0≦ _BVmax <9
The comparator circuit 53 outputs "1" when _BVmax <0, and outputs logic "0" otherwise. Gate circuits 54-56
are the maximum value BVmax _x , the average value BVmean and the minimum value
In order to selectively output BVmin to the output terminal 57, the outputs of the comparison circuits 51 to 53 are respectively applied.

Next, the operation will be explained.

(1) When BVma _x ≧9: In this case, the screen contains a fairly high-intensity subject, such as the sun, bright clouds, or a clear sky. Therefore,
In this case, the main subject often exists on the low-brightness side, and in order to prevent the subject on the low-brightness side from being darkened, the exposure is adjusted to a brightness around the minimum value BVmin. If you do this, there is a concern that the high-brightness side will be too bright, but since the film has a latitude, even the relatively high-brightness side will be properly exposed.

For this purpose, the comparison circuit 51 outputs "1", opens the gate 54, and outputs the minimum value BVmin to the output terminal 57.
to communicate.

(2) When 0≦ _BVmax <9; This case is a general daytime outdoor scene, an indoor scene, or a sunset scene. Therefore, in this case, it is necessary that the exposure is correct for the entire screen (although there is a main subject intended by the photographer, the exposure is correct only for this, making other subjects appear dark or bright). In order to prevent this, the exposure is adjusted to a brightness around the average value BVmean.

For this purpose, the comparison circuit 52 outputs "1", opens the gate 55, and transmits the average value BVmean to the output terminal 57.

(3) When BVma _x <0; In this case, it is a night view. In a night scene, the main subject is in a high-brightness area, so the exposure is adjusted to a brightness around the maximum value _BVmax .

For this purpose, the comparison circuit 53 outputs "1", opens the gate 56, and outputs the maximum value _BVmax to the output terminal 57.
to communicate.

The output of the output terminal 57 (appropriate photometry output) is applied to a known appropriate exposure calculation circuit, and used together with other exposure factors to calculate the appropriate aperture value or shutter speed. Exposure control and/or appropriate exposure display is performed based on this calculation output.

The above embodiments are effective when the object scene does not have a complicated brightness distribution, but if the brightness distribution is complicated, the exposure may not match the photographer's intention. An embodiment that solves this problem will be described below.

FIG. 5 is a block diagram of another embodiment of the invention. A photometric circuit 10 including the light receiving device 1 outputs photometric outputs PV ₀ , PV ₁ , . . . , PV _o-1 of each part of the photographic screen. Since these outputs are generally TTL photometered, the brightness BV ₀ , BV ₁ , . . . , BV _o-1 of each part of the screen is lowered by the maximum aperture AV ₀ of the lens. That is, PV ₀ = BV ₀ − AV ₀ PV ₁ = BV ₁ − AV ₀ 〓 〓 PV _o-1 = BV _o-1 − AV ₀ . Note that PV ₀ and BV ₀ are defined as the photometric output and brightness at the center of the screen.

The brightness calculation circuit 11 adds the photometric output PV _j =BV _j −AV ₀ (j=0 to _o-1 ) obtained by the photometric circuit 10 and the open aperture body AV ₀ from the information setting circuit 50, and calculates the absolute brightness. Get BV _j . 12, 13, and 14 are circuits for calculating the maximum value _BVmax , the average value BVmean, and the minimum value BVmin, respectively. In addition, the average value output circuit 13
is the brightness of each part at a certain value (for example, BV = 11)
When the output exceeds , the output is not included in the calculation. Also, when the number exceeds a certain value, calculations are performed by regarding the excess as a certain value (for example, BV=11). For example, when divided into 5 parts as shown in Figure 3, the brightness of each part is BV ₀ = 10, BV ₁ = 12,
When BV ₂ = 11, BV ₃ = 10, BV ₄ = 10.5,
Ignoring BV ₁ and BV ₂ , the average value is BVmean
=(10+10+10.5)/3=10.2 is output.

Also, the brightness of each part is BV ₀ = 11.5, BV ₁ = 12.5,
When BV ₂ = 12, BV ₃ = 10.5, BV ₄ = 10.5,
If we ignore BV ₀ , BV ₁ , and BV ₂ , there are many of them, so only one of BV ₀ , BV ₁ , and BV ₂ will be BV=11
Assuming that, the average value is BVmean=(11+
Outputs 10.5+10.5)/3=10.7.

The intermediate value output circuits 16 and 17 are ( _BVmax + BVmean)/2 and (BVmin +
BVmean)/2 is output. Brightness at the center of the screen
BV ₀ is taken from circuit 15.

When the number of divisions is large as shown in FIG. 1, the average brightness value based on the photometric outputs of several light receiving elements at the center of the screen is output. 18 to 22 are the maximum values in the comparison circuit
With BVmax _x as input, only one of the comparator circuits outputs logic “1” depending on the brightness level of BVmax _x .
Output. That is, the comparator circuit 18 determines that BVmax _x ≧11
Outputs “1” when .

Comparison circuit 19 is “1” when 11>BVmax _x ≧9
Output.

Comparison circuit 20 is “1” when 9>BVmax _x ≧5
Output.

Comparison circuit 21 is “1” when 5>BVmax _x ≧0
Output.

The comparison circuit 22 outputs "1" when 0> _BVmax .

The brightness difference calculation circuit 23 calculates dBV= _BVmax −BVmin (unit: EV) from the outputs of the maximum value output circuit 12 and the minimum value output circuit 13. The comparison circuits 24 to 27 receive the output dBV of the output circuit of the brightness difference calculation circuit as input, and the output dBV
It selectively outputs "1" depending on the level of the signal.

Specifically, the comparison circuit 24 outputs "1" when dBV≧5 [EV]. Comparison circuit 25 is 5>dBV≧3 [EV]
Outputs “1” when . The comparison circuit 26 is 3>
Outputs “1” when dBV≧2/3 [EV]. The comparison circuit 27 outputs "1" when 2/3>dBV [EV].

The comparison circuit 28 inputs the brightness BV ₀ at the center of the screen, which is the output of the circuit 15, and the maximum value _BVmax , which is the output of the minimum value output circuit 14, and when BV ₀ ≧ _BVmax −α (α: constant), “ Outputs 1”. That is, "1" is output when the high brightness area is at the center of the screen.

The comparison circuit 29 inputs the brightness BV ₀ at the center of the screen which is the output of the circuit 15 and the minimum value BVmin which is the output of the minimum value output circuit 14, and outputs "1" when BV ₀ ≦BVmin + α'(α' constant). do. That is, 1 is output when the low brightness portion is at the center of the screen.

Gate circuits 30 to 34 are circuits 12 and 1, respectively.
The outputs of circuits 6, 13, 17, and 14 are input, and the gates are selectively opened according to the output signals of gate circuits 35 to 46, and the outputs of the corresponding circuits of circuits 12, 16, 13, 17, and 14 are input. It is selected as the brightness to match the exposure and is transmitted to the output terminal 57. This is incorporated into the apex calculation system (not shown) of a normal camera to display appropriate exposure and control exposure.

FIG. 6 shows the brightness distribution of various scenes, with the horizontal axis representing the brightness [BV] and the vertical axis representing the probability distribution. Luminance distribution of a scene (shown by dotted line)
consists of the luminance distribution of the main subject (solid line peaks) and the luminance distribution of objects other than the main subject (hatched peaks). Since the maximum and minimum values are measured using a finite number of light receiving elements, they are located slightly inside the base of the mountain.
The difference between the maximum value and the minimum value is dBV.

Next, the operation will be explained according to the brightness pattern.

1 When BVma _x ≧11; In this case, the screen includes a fairly high-brightness subject, such as the sun or bright clouds. Since the output of the comparison circuit 18 becomes "1", the OR gate 37 becomes "1", and the gate circuit 32 opens.
BVmean is output to the apex calculation system. As already mentioned, the average value calculation circuit 13 calculates the brightness
Since the calculation ignores anything over BV=11, the exposure at this time will be adjusted to the main subject on the low-brightness side.

That is, in FIG. 6a, objects with luminance exceeding BV=11 (hatched peaks) are ignored, and exposure is adjusted to the main subject (solid line only peaks). At this time, the average value BVmean (A arrow indicated)
ignores luminance exceeding BV=11, so it is equal to the average value of the main subject itself.

Incidentally, when this neglect is not performed, BVmin is selected as shown in the example in FIG.

2 When 11>BVma _x ≧9; In this case, the subject includes the sky on a clear day, there is no extremely bright subject, and the output of the average value calculation circuit 13 also has no ignored brightness ( The same applies to the following cases).

At this time, the output of the comparison circuit 19 becomes "1",
The output of the OR gate 36 becomes "1". Therefore, the gate circuit 33 opens and the intermediate value calculation circuit 17
The output (BVmin+BVmean)/2 is transmitted to the apex calculation system.

In such subjects, the high brightness is often a bright sky or clouds, and the main subject is often low brightness, and there are many scenes where this output is appropriate.

That is, in FIG. 6b, the exposure is adjusted to the brightness (BVmin+BVmean)/2 indicated by arrow A.

3 When 9>BVmax _x ≧5; Such a scene is a common outdoor scene during the daytime, and the output of the comparator circuit 2 becomes "1". The output "1" of the comparator circuit 20 is subjected to various logical processing together with the outputs of the circuits 24 to 27 and the circuits 28 and 29 to determine the output to be transmitted to the output terminal 57 as follows.

a dBV≧5 [EV] The output of the comparison circuit 24 becomes “1”, the OR gate 43 becomes “1”, and the AND gate 44 becomes “1”
Then, the output of OR gate 36 becomes “1”,
The gate circuit 36 opens and (BVmin+BVmean)/
The output of step 2 is transmitted to the apex calculation system. 6th
This is a scene with a brightness distribution as shown in Figure c, where the difference in brightness is large and the main subject is on the low brightness side. The brightness indicated by arrow A in Figure 6c is (BVmin+
BVmean)/2.

b When 5>dBV≧3, the output of the comparison circuit 25 becomes “1”, the outputs of the OR gate 40, AND gate 41, and OR gate 37 each become “1”, and the gate circuit 32 opens.
BVmean is transmitted to the apex calculation system. Such a scene is a scene with a certain degree of brightness, and by adjusting the exposure to the average value, it is possible to provide a good photograph in which the dark areas are not too blurred and the bright areas are not too blown out.

The average value BVmean at this time is indicated by arrow A in FIG. 6d.

When c 3/2≦dBV<3 [EV], the output of the comparison circuit 26 becomes “1”. At this time, the following two judgments are made.

(B) When BV ₀ ≧ BVma _x −α, the output of the comparison circuit 28 becomes “1”, the output of the AND gate 38 becomes “1”, the gate circuit 31 opens, and the output of (BVma _x + BVmean)/2 is used for apex calculation. can be incorporated into the system.

In such a scene, the brightness at the center of the screen is high, and the difference in brightness is relatively small, so it is assumed that a bright object is in the center of the screen, where the probability that the main object will come is high. The exposure is adjusted to suit the brightness side. ( _BVmax + BVmean)/2 at this time is indicated by arrow B in FIG. 6e.

(b) When BV ₀ < _BVmax −α, the output of the comparison circuit 28 is “0”, and the NOT circuit 45, AND gate 39, OR gate 40, AND
The outputs of the gate 41 and the OR gate 37 become "1", the gate circuit 32 is opened, and BVmean is taken into the apex calculation system. This is because such scenes are best suited for average exposure. BVmean at this time is indicated by arrow A in FIG. 6e.

When d BV ₀ <3/2 [EV], the outputs of the two comparison circuits become "1". At this time as well, the following two judgments are made.

(a) When BV ₀ ≦BVmin+α, the output of the comparison circuit 29 becomes "1", the output of the AND gate 35 becomes "1", the gate circuit 34 is opened, and BVmin is taken into the apex calculation system.

This is a fairly flat scene, and the brightness is low in the center of the screen, where the main subject is likely to be present, so by adjusting the exposure to match the low-brightness area, the correct exposure can be obtained. BVmin at this time is indicated by arrow B in FIG. 6f.

(b) When BV ₀ > BVmin + α', the output of the comparison circuit 29 is "0", and the NOT circuit 46, AND gate 42, OR gate 43, AND
The outputs of the gate 44 and the OR gate 36 become "1", the gate circuit 33 is opened, and (BVmin
+BVmean)/2 is incorporated into the apex calculation system.

This is because the scene is quite flat, so even if the center of the screen is not low brightness, there is a high probability that the main subject will be on the low brightness side, and it is better to adjust the exposure to the low brightness side. . (BVmin+BVmean)/2 at this time is indicated by arrow A in FIG. 6f.

4 When 5>BVma _x ≧0; Scenes with such brightness are evening scenes and indoor scenes.

The output of the comparison circuit 21 becomes "1", the output of the OR gate 37 becomes "1", the gate circuit 32 is opened, and BVmean is taken into the apex calculation system.

In such a brightness range, the most favorable results are obtained when average exposure is applied. BVmean at this time is indicated by arrow A in Figure 6g.

5 When _BVmax <0; A scene with such brightness is a night scene.

The output of the comparison circuit 22 becomes "1", the gate circuit 30 is opened, and _BVmax is taken into the apex calculation system. In night scenes, the main subject is a high-brightness area, so favorable results can be obtained. _BVmax at this time is indicated by arrow A in Fig. 6h.

As described above, BVma _x , (BVma _x +
BVmean)/2, BVmean, (BVmin+
One of BVmean)/2 and BVmin is taken into the apex calculation system as an appropriate value. Let's call this value BVanser. Exposure and display control thereafter are performed using known apex calculation techniques. For example, when priority is given to shutter speed, the appropriate aperture value is determined by AV = BVanser + SV - TV, and when priority is given to aperture, the appropriate shutter speed is determined by TV = BVanser + SV - AV.

FIG. 7a shows a circuit example of the maximum value output circuit 12, and FIG. 7b shows a circuit example of the minimum value calculation circuit 14. These circuits use an OP amplifier and an ideal diode and are known per se.

Fig. 8 shows an average value calculation circuit 13 configured with resistors γ, γ/n and an OP amplifier A ₁ , and the output of the OP amplifier is (BV ₁ + BV ₂ ... BV _o-1 )/n=
An output called BVmean is obtained.

FIG. 9 shows a circuit example of the intermediate output circuits 16, 17, which are composed of followers _A10 to _A12 and voltage dividing resistors _R1 to _R4 .

FIG. 10 is a circuit diagram showing another embodiment of the average value calculation circuit 13.

When the brightness exceeding BV=11 is 0, all FETs conduct, so the composite feedback resistance R is γ/5 1/R=2/γ+2/γ+1/γ=5/γ, R=
γ/5 i.e. (BV ₀ /γ+BV ₁ /γ+...+BV _o-1 γ)・γ/5= BV

Claims (1)

[Scope of Claims] 1. In a multi-photometering device that divides a photographic screen into a plurality of areas and performs photometry and generates a plurality of photometry outputs corresponding to each area, the maximum value BVmax of the plurality of photometry outputs is detected. average value calculating means 13 for calculating the average value BVmean of the plurality of photometric outputs; minimum value detecting means 14 for detecting the minimum value BVmin of the plurality of photometric outputs; first intermediate value calculation means 16 for calculating an intermediate value between the average value BVmean and the maximum value BVmax;
and second intermediate value calculation means 17 for calculating an intermediate value between the average value BVmean and the minimum value BVmin.
and a first determination of comparing the maximum value with a first reference value for identifying a clear sky scene and a second reference value for identifying a sunset scene or an indoor scene, and determining the magnitude thereof. means 19 to 21; second determining means 28, 29 for determining the magnitude of brightness of the central area from among the plurality of photometric outputs regarding the central area of the photographic screen; and the maximum value and the minimum value. third determining means 23 to 27 for determining the magnitude of the difference; and when the first determining means determines that the maximum value is larger than the first reference value, the second intermediate value outputting means; When the first determining means determines that the maximum value is smaller than the second reference value, the average value calculating means outputs the output; When it is determined that the value is between the first reference value and the second reference value, an average value calculation means, a minimum value detection means, according to the outputs of the second and third determination means;
A multi-photometering device comprising photometric output generating means 30 to 46 for outputting the output of either of the first and second intermediate value calculating means as a photometric output for calculating appropriate exposure.