JPH06148715A - Photometric device for camera - Google Patents

Abstract

PURPOSE:To detect data for calculation of exposure with a comparatively simple program and to detect the appropriate exposure value from this data by carrying out divided photometry to a multiple number of photometric areas disposed in a matrix form according to the photometric mode. CONSTITUTION:One mode among a multiple number of photometric modes is set, the photometric area in the matrix form is divided into a multiple number of groups by a division means 26 so as to correspond a group to a mode, the information related to brightness is detected for each group for the multiple number of groups by a group information detection means 27 and the proper exposure value is detected based on the information for each group by an exposure arithmetic means 28.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photometric device for a camera, and more particularly to a photometric device for a camera including a single-lens reflex camera and a video camera.

[0002]

2. Description of the Related Art In recent years, split photometry has been generalized in photometric devices of cameras, and the number of divisions of photometric areas has been increasing year by year. By increasing the number of divisions, various shooting scenes are appropriately classified, and fine control according to the shooting scenes has become possible. Therefore, as for the classification of shooting scenes, the larger the number of divisions, the better.

[0003]

Regarding the division of the photometric area, as disclosed in Japanese Patent Laid-Open No. 3-32175, the area is divided into a plurality of areas not only in the central portion of the photographing screen but also in the periphery thereof. Although the number is increasing, even if a different photometric mode is set depending on the condition of the subject, and an attempt is made to divide into a plurality of regions as shown in one of (a) to (c) in FIG. However, in the above-mentioned publication, there is a problem in that the region cannot be divided according to the other photometric mode, and thus an appropriate exposure value cannot be obtained.

In FIG. 4, (a) shows a plurality of regions divided according to the portrait mode, (b) shows a plurality of regions divided according to the landscape mode, and (c) ) Indicates a plurality of regions divided according to the general photographing mode. Further, according to Japanese Patent Application Laid-Open No. 3-204628, a shooting scene is set, photometric outputs are selected from a plurality of areas based on the scene, and an exposure value is calculated using the selected photometric output. If the number of divisions is further increased, it may be impossible to select the photometric output necessary for detecting the proper exposure value even in the above-mentioned shooting scenes in all the regions, and therefore, the proper exposure value cannot be detected. Dots occur. Furthermore, when the number of divisions in the photometric area increases, in order to detect the proper exposure value,
The exposure calculation data including the maximum brightness value and the like must be obtained from each area, and the program for obtaining the data becomes rather large.

The present invention has been made in view of the above problems, and performs divided metering according to the metering mode. At this time, the data for exposure calculation is detected by a relatively simple program, and this data is used to determine the appropriateness. The purpose is to be able to detect the exposure value.

[0006]

To achieve the above object, the present invention has a large number of photometric regions (24) arranged in a matrix and a plurality of photometric modes according to FIG. Metering mode setting means (2
5), dividing means (26) for dividing the large number of photometric regions (24) into a plurality of groups according to the one photometric mode, and information regarding brightness for each of the plurality of groups. Group information detecting means (27) for detecting the exposure value, and exposure calculation means (2) for detecting an appropriate exposure value based on the information regarding the brightness of each group.
8) and.

[0007]

According to the above construction, one photometry mode is set by the photometry mode setting means (25) in FIG. 1 according to the state of the subject, and the dividing means (26) is set according to the mode. However, for example, as shown in FIG. 4B, the large number of photometric regions (24) are divided into a plurality of groups, and the group information detecting means (2
In 7), since the information on brightness is detected for each group, it is not necessary to obtain it for each pixel from the large number of photometric areas (24), but it can be obtained for each group with a relatively simple program.

At this time, since the group information detecting means (27) obtains the above-mentioned information from all the groups, the information includes data necessary for detecting the proper exposure value (maximum brightness value in group units). Is included, and an appropriate exposure value can be obtained by the exposure calculation means (28) based on the above-mentioned information including the data. Therefore, performing divided metering according to the metering mode and detecting the data for exposure calculation for each group with a relatively simple program,
An appropriate exposure value can be detected by the same data of each group.

[0009]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a block diagram showing the internal optical system of the single-lens reflex camera. In this figure, the light flux that has passed through the photographing lens 1 is incident on the photographer's eye through the quick return mirror 2, the diffusion screen 3, the condenser lens 4, the pentaprism 5 and the eyepiece lens 6. On the other hand, a part of the light flux diffused by the diffusing screen 3 is received by the light receiving element 9 through the condenser lens 4, the penta prism 5, the photometric prism 7, and the photometric lens 8.

The quick return mirror 2 is partially a half mirror, and the light passing through the mirror is reflected by the sub mirror 10 and is incident on the focus detecting means 11 below. The focus detection unit 11 is configured to detect the focus state of the substantially central portion of the object scene and drive and control the taking lens 1 so that the focus state is achieved. FIG. 3 is a block diagram which constitutes a photometric device for a camera according to an embodiment of the present invention, and a dotted block 9 located on the left side of the drawing shows the light receiving element 9 in FIG.

The light receiving element 9 is a storage type photoelectric conversion element such as a CCD sensor, and as shown in the inside of the block 9 indicated by a dotted line in FIG. 3, a light receiving and storage section 91, a transfer section 92, The voltage conversion unit 93, the storage gate unit 94, and the timing circuit 95 form the light receiving element 9.
In the above-described light receiving and accumulating portion 91, light receiving segments are arranged in a large number of photometric areas divided into a matrix of 20 rows and 12 columns as shown by reference numeral 24 in FIG. Is generated in the light receiving and accumulating portion 91.
Accumulated by. Further, the light receiving / accumulating unit 91 is adapted to measure the field just corresponding to the shooting screen.

The storage gate unit 94 in FIG. 3 instructs the light receiving and storing unit 91 to start and end the charge storage in response to the signal from the storage time setting unit 18, and the light receiving and storing unit 91 receives the charge by this command. Is accumulated or the accumulation is terminated. The accumulation time setting unit 18, based on the information from the exposure calculation unit 16,
The optimum accumulation time for the next accumulation is calculated to adjust the accumulated charge amount.

The timing circuit 95 includes a clock generator 1
9 receives the supply of the master clock, creates various timing pulses necessary for the charge transfer, and the transfer unit 92 converts the charge stored in the light receiving and storing unit 91 into a voltage for each pixel in accordance with the timing pulse. Transfer to the unit 93. The voltage conversion unit 93 converts the charge from the transfer unit 92 into a voltage signal for each pixel and outputs the voltage signal to the A / D conversion unit 12.

The A / D converter 12 converts the voltage signal from the light receiving element 9 into a numerical signal (photometric output value) that can be recognized by the computer, and the numerical signal is converted into a numerical signal.
2 is output to the group brightness calculation unit 15. Furthermore,
The photometric mode setting unit 13 in the figure includes a selection button provided on the body of the camera or the like, and when the button is pressed, one of a plurality of photometric modes, portrait mode, landscape mode, or general shooting mode is selected. It is like this. The selection mode is transmitted to the group creation unit 14,
The group creating unit 14 divides the large number of photometric regions 24 into a plurality of groups according to any one of (a) to (c) in FIG. 4 according to the selection mode. still,
The group creating unit 14 is used as the dividing unit 26 in FIG.

The selection mode is the group creation unit 14
Is transmitted to the group brightness calculation unit 15, and the group brightness calculation unit 15 calculates as follows. First, the average value V (x) of the photometric output is calculated for each group based on the photometric output value of each area from the A / D conversion unit 12 and the photometric mode from the group creation unit 14. This average value V (x) indicates the average value of the photometric outputs of all the photometric areas belonging to one group, and for example, the average value of the photometric outputs of all the photometric areas belonging to group P1 in FIG. 4 (a). Is V (P1).

Next, the correction value calculated by the correction data calculation unit 21 based on the information from the in-lens ROM 20, the accumulation time t from the accumulation time setting unit 18, and the above-mentioned average value V (x) are used. Then, the brightness value BV (X) is calculated for each group in accordance with the equation of Formula 1.

[0017]

## EQU00001 ## BV (x) = log (V (x) .k (x) /
t) / log (2) In this equation, the logarithm with the base 2 on the right side is taken for the purpose of converting to a brightness value based on the Apex method, and the unit of the brightness value BV (X) is (EV) or (BV). Further, k (x) in the equation 1 is a correction value obtained by the above-mentioned correction data calculation unit 21, and is calculated from the open aperture value, the exit pupil position, the vignetting information, etc. input from the in-lens ROM 20. It is a unique correction value required for each group, and is obtained in advance by experiment or simulation in association with each group.

The above-mentioned A / D conversion unit 12 includes the components 91 to 91.
With the light receiving element 9 including 95, a photometric unit for outputting each photometric information from each of the plurality of photometric regions is configured, and the photometric unit and the group luminance calculation unit 15 configure the group information in FIG. The detecting means 27 is configured. The selected photometry mode is also transmitted to the exposure calculation unit 16 by the photometry mode setting unit 13, and the calculation unit 16 calculates the brightness value BV of each group by the group brightness calculation unit 15.
An exposure calculation is performed based on (x) and the selection mode to calculate an appropriate exposure value. The method of exposure calculation will be described later.

In accordance with the above-mentioned proper exposure value, the exposure control unit 1
7 calculates the aperture value and the shutter speed value, and when a release button (not shown) is pressed, the mirror 2 is flipped up, and the aperture 22 and the shutter 23 are controlled according to the above calculated values, whereby the exposure control is performed. Done. Photometric counting unit 2 located above the storage time setting unit 18 in the figure
Reference numeral 9 is for counting photometry, and the signal composition section 30 connected to the A / D conversion section 12 is for composition of photometric output values. The synthesis will also be described later.

Next, the necessity of adjusting the storage time of the light receiving element 9 by the storage time setting unit 18 will be described. Generally, the photometric range required for the photometric device of a camera is EV0
~ EV20, ie 20E in dynamic range
It is about V. However, the current CCD has a dynamic range of only about 10 EV. So CC
Therefore, it is necessary to adjust the storage time of D to set the required photometric range to the optimum level including the main subject.

Specifically, the brightness value in the object scene is EV0 to EV0.
With the EV 20, the illuminance on the surface of the light receiving element is about 0.01 Lx to 10000 Lx when the standard taking lens is mounted in the optical system in FIG. The sensitivity of the light receiving element is about 20V / lx · S, and the saturation output is about 2V.
Therefore, when the storage time is 10 μSec, the photometric range is about EV10 to EV20, and the storage time is 10 m.
When it is Sec, the photometric range is EV0 to EV10.

That is, the storage time of the light receiving element is set to 10 μS.
By operating in the range of ec to 10 mSec, the EV0 to E which is the photometric range required for the photometric device of the camera for the first time.
The dynamic range of V20 can be realized. For the above-mentioned reason, when photometry is performed using the CCD, the photometry range for one photometry is limited to the range of 10 EV, but the dynamic range of the silver salt film is 10 EV.
Since it is smaller than the above, no problem occurs.

FIG. 5 is a flow chart showing the operation of each of the components 13 to 21, the photometric counting section 29, and the signal synthesizing section 30 shown in FIG. The operation will be described using. “K” shown in step 101 indicates the number of times of photometry in the flowchart, and here, the photometry count unit 29 in FIG. 3 sets the initial value “1” to the number of times of photometry k.
When k = 1, it indicates the first photometry, and when k ≠ 1, 2
Indicates photometry for the second time and above.

In step 102, the number of photometric measurements k is "1".
The photometric counting unit 29 determines whether or not it is, and if it is the first time, the process proceeds to step 103, or if it is the second time or more, the process proceeds to step 105. In step 103, the photometry counting section 29 sets the photometry count k to "0".
Is substituted, and the process proceeds to the next step 104 to execute photometry. The photometry will be described later.

In step 102, when the number of photometry is two or more, the process proceeds to step 105, the accumulation time setting unit 18 reads the accumulation time t and sets the time t, and the accumulation time t is the same as the previous time. It is obtained in step 111 based on the photometric value. A method for obtaining the time t will also be described later. In step 106, photometry is performed during the accumulation time t, that is, the A / D converter 12 converts each pixel into a numerical signal (photometric output value) according to the output of the light receiving element 9, Output to the brightness calculation unit 15,
The calculator 15 stores 240 photometric output values.

In step 107, the group creating section 14
The meter reading mode is read from the metering mode setting unit 13, and the modes are the three types of portrait mode, landscape mode, and general photographing mode as described above, and are set by the photographer. Proceeding to step 108, the group creating unit 14 divides the 240 photometric areas 24 into a plurality of groups according to the above-described photometric mode, as shown in each figure in FIG. 4 shows the groups P1 to P7 shown in (a) of FIG. 4, the groups L1 to L6 shown in (b) in the landscape mode, and the groups shown in (c) in the general photographing mode. Groups H1 to H6
Split into.

When this division is completed, the routine proceeds to step 109, where the group brightness calculator 15 calculates as follows. First, the average value V (x) of the photometric outputs of all the regions belonging to one group is calculated for each group according to the 240 photometric output values stored in step 106 and the mode from the group creating unit 14. To do. Next, the above-mentioned correction value k from the correction data calculation unit 21 and the accumulation time setting unit 1
Using the accumulation time t from 8 and the above-mentioned average value V (x), the brightness value BV (X) of each group is calculated by the equation (1).

At the next step 110, the exposure calculation section 24 calculates an appropriate exposure value BVans using the brightness values of the respective groups described above. A method for obtaining this value BVans will also be described later. In step 111, the accumulation time setting unit 18 calculates the accumulation time t at the next photometry and stores the time t. The calculation of the accumulation time t will also be described later.

In step 112, focus detection is performed and focus adjustment is performed so that the taking lens 1 is in focus. If the focus matches, the routine proceeds to step 113, where it is determined whether or not a release button (not shown) is fully pressed. If not, go back to step 102,
When the photometry is performed or the full-press is performed in the same manner as described above, the process proceeds to the next step 114, and the exposure control unit 25 drives the diaphragm member 10 and the shutter 11 based on the appropriate exposure value BVans obtained in step 110. Exposure control. After that, the operation according to the flowchart in FIG. 5 ends.

FIG. 6 is a flowchart of a subroutine for performing the initial photometry based on step 104 in FIG. 5, and the initial photometry will be described with reference to this flowchart. In step 201, the accumulation time setting unit 18 sets “t1” in the accumulation time t. This “t1” is a predetermined value, t1 = 10 μSec, and the photometric range is EV10 to EV20.

Proceeding to step 202, photometry is performed during the above-mentioned accumulation time t1 (= 10 μSec). That is, according to the output of the light receiving element 9, the A / D conversion unit 12 converts each pixel into a numerical signal (photometric output value) and outputs the numerical signal to the signal synthesizing unit 31. Store the output value. In step 203, the accumulation time setting unit 18
Sets "t2" to the accumulation time t. This "t2"
Is a predetermined value, t2 = 10 mSec, and the photometric range is EV0 to EV10.

In step 204, during the above-mentioned accumulation time t2, photometry is performed in the same manner as in step 202 and output to the signal synthesizing section 31, and the synthesizing section 31 stores 240 photometric output values. In step 205, the photometric output values stored in step 202 and step 204 are taken out by the signal synthesizing unit 31 and synthesized. When the accumulation time t is t1, the photometric range is EV10 to EV20,
When the accumulation time t is t2, the photometric range is EV0 to EV1.
Since it is 0, the photometric output values are combined corresponding to the dynamic range of EV0 to EV20 based on the results of these two photometric measurements.

Specifically, the 240 photometric output values obtained in step 202 are searched, and for the area of EV 10 or less, the photometric output value of the same area at the accumulation time t2, that is, step 204. The photometric output value of the same area in the above is set as the photometric result, and for the area other than that, the photometric output value of the same area at the accumulation time t1, that is, the photometric output value of the same area in step 202 is set as the photometric result. At this time, in order to correct the difference in output due to the difference in storage time, log (t2 /
t1) / log2 shall be added.

The synthesis is performed as described above, and thereafter, the process returns to the flowchart of FIG. 5 and proceeds to step 107. Figure 7
Is calculated based on step 110 in FIG.
Shows a flowchart of a subroutine for performing exposure calculation, and the exposure calculation will be described using this flowchart.

In step 301, the photometric mode setting unit 1
It is determined whether or not the photometric mode is the portrait mode according to the output of 3. If so, step 30
Proceeding to step 2, exposure calculation for portrait mode is performed to calculate an appropriate exposure value. The calculation will be described later.
If not in portrait mode, step 30
In step 3, it is determined whether the photometric mode is the landscape mode. If so, proceed to step 304,
Perform the exposure calculation for landscape mode to calculate the appropriate exposure value. The calculation will also be described later.

Further, when neither the portrait mode nor the landscape mode is set, it is the general photographing mode. At this time,
In step 305, the exposure calculation for the general shooting mode is performed to calculate an appropriate exposure value. The calculation will also be described later. As described above, after the exposure calculation is performed according to the set photometric mode and the appropriate exposure value is calculated, the process returns to the flowchart of FIG. 5 and proceeds to step 111.

FIG. 8 is a flow chart when the exposure calculation section 16 performs the exposure calculation according to the portrait mode based on step 302 in FIG. 7, and the exposure calculation in the portrait mode will be described using the flowchart. To do. First, the brightness values BVp1 to BVp7 of the groups P1 to P7 in FIG. 4A, which are calculated by the group brightness calculation unit 15 in accordance with step 109 in FIG. 5, are read out, and then the brightness values of the groups P2 to P5 are read. The maximum brightness value is assigned to BVp25 from each of BVp2 to BVp5. This substitution is shown in step 401 in FIG.

At the next step 402, it is determined whether or not the expression of the equation 2 is satisfied, that is, whether or not BVp25 is brighter by 2 EV or more than the brightness value BVp1 of the group P1.

[0039]

## EQU00002 ## BVp25-BVp1> 2 When this expression is satisfied, the main subject located in the center of the screen where the focus detection area is located is extremely small and in the backlight condition, so the procedure proceeds to step 403. The brightness value BVp1 of the group P1 is detected as an appropriate exposure value BVpo. When the expression of the equation 2 is not established, step 404
Then, it is determined whether the equation 3 is satisfied, that is, whether the brightness value BVp6 of the group P6 is brighter by 2 EV or more than the above-mentioned BVp25.

[0040]

[Formula 3] BVp6−BVp25> 2 When this formula is established, the main subject is relatively small and the backlight is on, so the routine proceeds to step 405, where the appropriate exposure value BVpo is calculated from the formula 4 calculate.

[0041]

## EQU00004 ## BVpo = (BVp1 + BVp25) / 2 When the expression of the expression 3 is not established, the process proceeds to step 406, and whether or not the expression of the expression 5 is established, that is, the brightness value BVp7 of the group P7 is different. It is determined whether the brightness value BVp6 of the group P6 is 2 EV or more.

[0042]

## EQU00005 ## BVp7-BVp6> 2 When this formula is established, the main subject is in the backlit state, so the routine proceeds to step 407, and the appropriate exposure value BVpo is calculated from the formula of Formula 6.

[0043]

[Formula 6] BVpo = (BVp1 + BVp25 + BVp6) / 3 When the formula of Formula 5 is not established, it is a general scene, so the process proceeds to Step 408, and the appropriate exposure value BVpo is calculated from the formula of Formula 7. To do.

[0044]

[Equation 7] BVpo = (BVp1 + BVp25 + BVp6 + BV
p7) / 4 In the above calculation, the proper exposure value BVpo is detected in step 403, or step 405, step 4
07 or the proper exposure value BVpo by step 408
After calculating, the process returns to the flowchart in FIG. 5 and proceeds to step 111.

FIG. 9 is a flow chart when the exposure calculation section 16 performs the exposure calculation according to the landscape mode based on step 304 in FIG. 7, and the exposure calculation in the landscape mode will be described using the flowchart. First, the brightness values BVl1 to BVl6 of the groups L1 to L6 in FIG. 4B detected by the group brightness calculation unit 15 according to step 109 in FIG. 5 are read out, and then the brightness value BVL6 of the group L6 is read. 16.3 Determine if it is greater than EV. This determination is shown in step 501 in FIG. 9, and when the determination is negative, the process proceeds to step 503, where
The appropriate exposure value BVLA is calculated by the equation.

[0046]

[Equation 8] BVL A = (BVL1 + BVL2 + BVL3 + BVL4 +
BVL5 + BVL6) / 6 When the above-mentioned brightness value BVL6 is larger than 16.3 EV, there is an unnecessary high-brightness subject such as the sky or the sun in the area L6, so the routine proceeds to step 502, where appropriate exposure is performed. The value BVLA is calculated according to the equation (9).

[0047]

[Equation 9] BVL A = (BVL1 + BVL2 + BVL3 + BVL4 +
BVL5) / 5 Once the proper exposure value is calculated in step 502 or step 503, the process then returns to the flowchart in FIG. 5 and proceeds to step 111. FIG. 10 shows the exposure calculation unit 1.
6 is a flowchart for performing exposure calculation according to the general shooting mode based on step 305 in FIG.
The exposure calculation in the general shooting mode will be described with reference to the flowchart.

First, the brightness values BVh1 to BVh6 of the groups H1 to H6 in FIG. 4C detected by the group brightness calculation unit 15 in accordance with step 109 in FIG. Whether or not the expression is satisfied, that is, the brightness value BVh1 in the group H1 in FIG. 4C is 2EV higher than the brightness value BVh6 in the group H6.
It is determined whether it is brighter than the above. This determination is shown in step 601.

[0049]

[Formula 10] BVh1−BVh6> 2 When this formula is established, the main subject is extremely small and the backlight is on, so the routine proceeds to step 602, where the proper exposure value BVhf is calculated by the formula 11 calculate.

[0050]

[Equation 11] BVhf = (5BVh6 + BVh1 + BVh2 + BVh3 + BVh4 + B
Vh5) / 10 When the expression of the expression 10 is denied, the routine proceeds to step 603, and the maximum brightness value is substituted into BVh25 from each of the brightness values BVh2 to BVh5 of each group H2 to H5. The process proceeds to the next step 604, and it is determined whether or not the expression of Expression 12 is established.

[0051]

[Formula 12] BVh25−BVh1> 2 When this formula is established, the main subject is relatively small and is in the backlight condition, so the routine proceeds to step 605, where the proper exposure value BVhf is calculated by the formula 13 calculate.

[0052]

[Formula 13] BVhf = (3 ・ (BVh1 + BVh6) + BVh2 + BVh3 + BVh4
+ BVh5) / 10 When the expression of Expression 12 is denied, it is a general scene, so the routine proceeds to step 606, and the appropriate exposure value BVhf is calculated by the expression of Expression 14.

[0053]

BVhf = (BVh6 + BVh1 + BVh25) /
3 The exposure calculation in the general photographing mode is performed as described above, and an appropriate exposure value is calculated in step 602, step 605, or step 606, and thereafter, the process returns to the flowchart in FIG. 5 and proceeds to step 111. FIG. 11 shows FIG.
3 is a flowchart of a subroutine showing a process for the storage time setting unit 18 in FIG. 3 to calculate the next optimum storage time t based on step 111 in FIG. 3, and the calculation of the storage time t will be described using this flowchart. To do.

In step 701, "BVmax-BVmi
It is determined whether or not n <10 is satisfied. That is, it is determined whether or not the value obtained by subtracting the minimum brightness value BVmin from the maximum brightness value BVmax is smaller than 10 EV among the brightness of each group divided according to the set photometric mode. When it is smaller than 10 EV, it is considered that all 240 pieces of photometric data are included in one photometric dynamic range. At this time, the process proceeds to step 702,
The next photometric reference level BVt is calculated by the equation (15).

[0055]

[Equation 15] BVt = (BVmax + BVmin) / 2 BVt is obtained when photometry is performed at a certain storage time.
It is a luminance value that gives a photometric value equivalent to half the saturation level of the photometric output, and for example, the photometric range is EV10-E.
In the case of V20, BVt = 15. Further, when the value exceeds 10 EV in the above step 701, it means that there is data equal to or higher than the photometric upper limit value or equal to or lower than the photometric lower limit value in the previous photometry, and at this time, step 703.
Then, the number Nmax of high-brightness photometry limit data in the previous photometry is counted.

After the count, the process proceeds to step 704, where the number Nmi of low-luminance photometry limit data in the previous photometry is Nmi.
Count n. Further proceeding to step 705, the photometric reference level BVt in the previous photometry is calculated according to the equation (16). Here, t is the accumulation time in the previous photometry.

[0057]

## EQU16 ## BVt = log (0.32 / t) / log
2 For example, when t = 0.01 seconds, BVt = 5. After the above-mentioned reference level BVt is calculated, the routine proceeds to step 706, where the next photometric reference level BVt is calculated using the previous photometric reference level according to the equation (17).

[0058]

## EQU17 ## BVt = BVt + (Nmax-Nmin) / 1
0 When Nmax is greater than Nmin, this formula works to increase the next photometric reference level from the previous time because there is more high-luminance photometric limit data, and conversely, when Nmin is greater than Nmax. Has a lot of low brightness photometric limit data,
It works to lower the next photometric reference level from the previous time.
Here, the level shift amount is optimized by setting Nmax-Nmin to 1/10, but the value is not limited to 1/10, and each optimized value may be used.

In step 707, it is determined whether or not the next photometric reference level BVt is more than 15 as shown in the equation (18).

[0060]

[Formula 18] BVt> 15 When this formula is established, the photometric reference level has exceeded the photometric upper limit, so the routine proceeds to step 708, where the next photometric reference level BVt is set to the photometric upper limit “15”. "
And At this time, the photometric range is EV10 to EV20. If the next photometric reference level BVt is less than 15 in step 707, step 709
Then, as shown in the equation (19), it is determined whether or not the next photometric reference level BVt is less than 5.

[0061]

[Formula 19] BVt <5 When this formula is established, the photometric reference level has exceeded the photometric lower limit, so the routine proceeds to step 710, and the next photometric reference level BVt is set to the photometric lower limit of “5”. ". At this time, the photometric range is EV0 to EV10.
In Step 711, Step 702 and Step 708
Alternatively, the next accumulation time t is calculated from the reference level BVt obtained in step 710 by the formula of Formula 20, and the time t is stored in the setting unit 18 itself.

[0062]

T = 0.32 / (2 ^ BVt) where the ^ mark represents a power. After storing the above time t, the process proceeds to step 112 in FIG.
After that, the same operation as described above is performed. According to the above embodiment, the light receiving element 9 including the components 91 to 95 in FIG.
A group information detecting unit 27 in FIG. 1 is configured by the photometric unit including the D conversion unit 12 and the group luminance calculating unit 15, and the group information detecting unit 27 detects the luminance value of each group for each group. Although it has been stated that the exposure calculation unit 28 calculates an appropriate exposure value from the brightness value of each group, the present invention uses a camera such as a lens shutter camera that calculates an appropriate exposure value from the photometric output of the photometric unit. Also in, it is possible to operate as follows.

The group information detecting means 27 detects the respective photometric output values from the large number of photometric areas 24, and based on the respective photometric output values and the above-mentioned photometric mode, outputs the photometric output values in group units. It is also possible to calculate for each group and use the photometric output value of each group to cause the exposure calculation means 28 to calculate an appropriate exposure value. Further, in the above-described embodiment, the photometry when the present apparatus is provided in the single-lens reflex camera has been described, but it goes without saying that the present invention can be applied to a video camera or the like.

[0064]

As described above, according to the present invention, when changing the photometric mode depending on the condition of the subject, one photometric mode is set by the photometric mode setting means, and the one photometric mode is set for the multiple photometric areas. Since the groups are divided according to the mode and the information on the brightness is detected for each group, the data for exposure calculation can be detected for each group with a relatively simple program.

Further, in order to detect the above-mentioned information from all the groups, the information includes data necessary for detecting the proper exposure value (maximum brightness value in group unit, etc.),
Therefore, the exposure calculation means can obtain an appropriate exposure value based on the above information.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention.

FIG. 2 is a diagram showing a configuration of an internal optical system of a single-lens reflex camera.

FIG. 3 is a block diagram showing a configuration of a photometric device for a camera according to an embodiment of the present invention.

FIG. 4 shows a state in which a large number of photometric areas 24 in FIG. 1 are divided into a plurality of groups according to a photometric mode,
4A shows a state when divided according to the portrait mode, FIG. 4B shows a state when divided according to the landscape mode, and further, FIG. 4C shows a general state. The figure shows a state when divided according to the shooting mode.

5 is a flowchart showing the operation of each of the components 13 to 21, the photometric counting unit 29, and the signal synthesizing unit 30 shown in FIG. 3 when the microcomputer is configured by one microcomputer.

FIG. 6 is a flowchart of a subroutine for performing initial photometry based on step 104 in FIG.

FIG. 7 is a flowchart of a subroutine for performing exposure calculation based on step 110 in FIG.

FIG. 8 is a flowchart of a subroutine for performing exposure calculation according to the port trade mode based on step 302 in FIG.

FIG. 9 is a flowchart of a subroutine for performing exposure calculation in landscape mode based on step 304 in FIG. 7.

FIG. 10 is a flowchart of a subroutine for performing exposure calculation according to the general shooting mode based on step 305 in FIG. 7.

11 is a flowchart of a subroutine for calculating a next optimum accumulation time t based on step 111 in FIG.

[Explanation of symbols]

1 shooting lens, 2 quick return mirror, 3
Diffusing screen 4 Condenser lens, 5 Penta prism, 6
Eyepiece lens 7 Photometric prism, 8 Photometric lens, 9 Light receiving element 10 Sub-mirror, 11 Focus detector, 12 A /
D conversion unit 13 metering mode setting unit, 14 group creation unit 15 group luminance calculation unit, 16 exposure calculation unit, 1
7 Exposure Control Section 18 Accumulation Time Setting Section, 19 Clock Generation Section, 2
0 In-lens ROM 21 Correction data calculation unit, 22 Aperture, 23 Shutter 24 Photometric means, 25 Photometric mode setting means, 26
Dividing means 27 Group information detecting means, 28 Exposure calculating means 91 Light receiving / accumulating section, 92 Transfer section, 93 Voltage converting section 94 Accumulating gate, 95 Timing circuit

Claims (3)

[Claims] 1. A plurality of photometric areas arranged in a matrix, a plurality of photometric modes, and a photometric mode setting means for setting one of the photometric modes, and the plurality of photometric areas to the one photometric area. Dividing means for dividing into a plurality of groups according to the mode, group information detecting means for detecting information on the brightness for each of the plurality of groups, and based on the information on the brightness of each group A photometric device for a camera, comprising: an exposure calculation unit that detects an appropriate exposure value. 2. The group information detecting means includes a photometric unit that detects photometric information for each area from the plurality of photometric areas, and the group information detecting means includes the photometric area for each of the plurality of groups. The brightness value of each group is calculated for each group from the photometric information of, and the exposure calculation means detects an appropriate exposure value based on the brightness value of each group for each group. 1. A camera photometric device according to 1. 3. The exposure calculation means has different exposure calculations for each of the plurality of photometric modes, and the exposure calculation means uses the brightness value of each group for each group, The photometric device for a camera according to claim 2, wherein an appropriate exposure value is detected by performing an exposure calculation according to one photometric mode.