JP2979417B2 - Multi-photometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. INDUSTRIAL APPLICATION Field of the Invention The present invention divides a specific area of an object scene into a plurality of small areas and performs photometry. The present invention relates to a multi-photometer that calculates an appropriate exposure value using the photometric output of the multi-photometer.

B. Prior Art Conventionally, this type of apparatus has been disclosed in JP-A-62-255921 and JP-A-1-105221.

Japanese Patent Application Laid-Open No. 62-255921 discloses a photometric device that includes a distance measuring device that measures the distance of a plurality of regions of an object scene, and a photometric device that measures light in the same region as the distance measuring device. Is singular, the photometric value in that area is used as the photometric output. In addition, when there are a plurality of selected ranging areas, it is determined whether or not a central area is included in the selected ranging areas. If the central area is included, a photometric value of the area is used as a photometric output. If not included, the average value of a predetermined photometric area is used as the photometric output.

Japanese Patent Application Laid-Open No. 1-105221 discloses a photometric device that performs focus detection for a plurality of regions or a plurality of points in an object field, and photometry that performs spot photometry for a plurality of regions that are the same as the in-focus detection regions or points or a region including the same. Means for selecting a distance measurement area in which the photographing lens should be focused based on the focus detection result, a photometry value of a photometry area corresponding to the selected area is selected, and the selected photometry value is selected. Exposure display or control is performed based on the value.

C. Problems to be Solved by the Invention These conventional devices have the following problems.

(A) Although it is possible to determine whether the subject is singular or multiple from the distance measurement result, the size and distribution of the subject cannot be determined. The photographing magnification is calculated from the focal length of the photographing lens, the approximate size of the subject is estimated, and which of the divided photometric elements is used is determined. Therefore, if the subject is not a person, or if the subject is a subject such as a child, the size of which is different from that of an adult, the size of the predicted subject differs greatly from the size of the actual subject, An appropriate photometric area was not always selected.

(B) In these conventional devices, even if it is possible to measure a distance in a plurality of areas and select a subject in any of the areas based on the result, it is not possible to select a part in a certain distance measurement area. It was not possible to identify whether the subject was present. For this reason, the location where the subject exists can be specified only in the ranging area unit, and therefore, the photometric output can be obtained only with a positional accuracy of at most about the ranging area, and an accurate photometric output of only the subject can be obtained. Could not be obtained.

(C) Further, in the above-described apparatus, since the divided photometry area is fixed, if the subject moves over the boundary line of the photometry area, the photometry output of the subject becomes extremely unstable. was there.

A technical object of the present invention is to determine the exposure value of the entire object field more precisely by detecting the size and distribution state of a main object by finely metering a specific area in the object field.

D. Means for Solving the Problems To be described with reference to FIG. 1 which is a diagram corresponding to claims, the invention of claim 1 divides an object field into a plurality of large areas and reduces the intensity of light incident on each area. A first signal output unit for outputting a first signal corresponding to the first signal output unit, and a specific area of the object scene is divided into a plurality of small areas smaller than the divided area of the first signal output means 101, and each small area is A second signal output means 102 for outputting a second signal corresponding to the intensity of light incident on the second and a focusing operation based on the second signal output from the second signal output means 102 Subject determining means 103 for determining which of the small areas the main subject to be included is included in,
A brightness calculating means 10 for calculating the brightness of the main subject using at least the second signal output from the small area where the subject determined to be the main subject by the subject determining means 103 is present.
And an exposure value calculating means 105 for calculating an appropriate exposure value based on the luminance of the main subject calculated by the luminance calculating means 104 and the first signal from the first signal output means 101. And

According to a second aspect of the present invention, in the multi-photometer according to the first aspect, the second signal output from the second signal output means 102 is provided.
A focus detection calculation unit 106 that performs a focus detection calculation on a subject existing in a specific area based on the signal of the focus detection calculation unit 106, based on the focus detection calculation result of the focus detection calculation unit 106. It is characterized in that the position and size of the main subject to be focused are extracted to determine where the main subject exists in the small area.

According to the third aspect of the present invention, a photometric unit 301 that divides an object field into a plurality of large areas and obtains a photometric output for each area, and a plurality of specific areas of the object field that are smaller than the divided area of the photometric unit 301 A signal output unit 303 that divides the image into small areas and outputs a photoelectric conversion signal according to the luminance of a subject present in each small area;
For each of the m (n> m) focus detection areas composed of n small areas of the plurality of small areas, focus detection calculation is performed based on the photoelectric conversion signal to obtain m defocus amounts. , A small area photometric value calculation means 308 for calculating the photometric value of each small area based on the photoelectric conversion signal from the signal output means 303, and m focus detection areas in those areas. Grouping means for grouping into j (m> j) groups according to the defocus amount of
4. A selecting unit 305 for selecting one optimal group in which an image of a subject to be focused is expected to be formed from the j groups, and a plurality of groups calculated by the small area photometric value calculating unit 308. Luminance calculating means 306 for calculating the luminance of the main subject using at least the photometric value corresponding to the area of the group selected by the selecting means 305 among the photometric values; and the luminance of the main subject calculated by the luminance calculating means 306 And photometric means 301
And an exposure value calculating means 307 for calculating an appropriate exposure value based on the photometric output from the camera.

E. Function In the first aspect of the present invention, the area including the main subject is determined based on the second signal output from the small area of the second signal output means 102 which is relatively finely divided, and the second area of the area is determined. The luminance of the main subject is obtained from the signal output of. And
Based on the luminance of the main subject and the first signal output from the area of the first signal output unit which is relatively large divided, the exposure calculation unit 105 calculates an exposure value for making the entire screen an appropriate exposure amount. I do.

According to the second aspect of the present invention, the main subject is determined based on the focus detection result calculated by the second signal output, and the main signal is selected from the second signals from the small area corresponding to the focus detected area. The luminance of the main subject is calculated from the second signal output from the small area determined to include the subject. Then, the exposure value is calculated in the same manner as in the first aspect.

According to the third aspect of the present invention, a plurality of regions are grouped based on the defocus amount as the focus detection result, and a group having a high probability of containing the main subject is selected. Focus adjustment is performed based on the defocus amount of the group, and the luminance of the main subject is also obtained from the photoelectric conversion signal output from the area of the signal output unit included in the group. Then, the exposure value is calculated in the same manner as described above.

F. Embodiment -First Embodiment- A first embodiment will be described with reference to FIGS. First
FIG. 2 is a block diagram showing a multi-photometer according to the first embodiment.

<Regarding Distance Measuring System> Reference numeral 1 denotes a distance measuring element for measuring a distance to a subject, and includes, for example, a pair of CCD array sensors 1-1 and 1-2 as shown in FIG. As shown in FIG. 3, a part of the light beam that has passed through the different areas of the exit pupil of the photographing lens 21 passes through the main mirror 22 and is reflected by the sub-mirror, as shown in FIG. The lens 24 is mounted at a position where a pair of subject images are re-formed on the distance measuring element 1 respectively. Here, the luminous flux re-imaged on the distance measuring element 1 corresponds to the distance measuring area of the subject screen shown in FIG.
It corresponds to 41. Charges proportional to the incident light intensity are accumulated in each of the array sensors 1-1 and 1-2 constituting the distance measuring element 1, and the accumulated charges are sequentially read out.
It is output to the distance measurement circuit 2 as contrast information.

The distance measuring circuit 2 calculates a pair of contrast information from the distance measuring element 1, calculates a relative shift amount between the array sensor outputs, and converts the shift amount into a defocus amount.
At this time, when the outputs of all the photoelectric conversion cells of each of the array sensors 1-1 and 1-2 are connected to one to perform a comparison operation, that is, in FIG. 4, the array sensors 1-1 and 1-2 are output.
Are compared, only one defocus amount is obtained. However, in the distance measuring circuit 2, the outputs of the respective array sensors are represented by 1A to 1C shown in FIG.
And 1A 'to 1C', 1A and 1A ', 1B and 1
By comparing B ', 1C and 1C', three defocus amounts can be obtained. In other words, this is equivalent to dividing the ranging area 41 shown in FIG. 6 into three areas and obtaining three ranging results. Similarly, if each array sensor is divided into p regions and subjected to a comparison operation, p defocus amounts are obtained, and therefore, a distance measurement result obtained by dividing the distance measurement region 41 into p can be obtained. Here, p can take an arbitrary numerical value up to the number of the distance measuring circuits 2 arranged on each array sensor.

At this time, it is not necessary to calculate all the defocus amounts of the plurality of divided distance measurement areas. Further, it is also possible to divide the plurality of divided distance measurement areas so that they overlap each other. Further, the number and position of the distance measuring circuits 2 used for the distance measuring operation can be arbitrarily selected as needed, and the position and size of the distance measuring area can be freely selected within the range of the distance measuring area 41. It is also possible to do it.

Normally, in such an apparatus, the number of photoelectric exchange cells on each array sensor is several tens or more, and when compared with the size of the ranging area, for example, the width of the ranging area is smaller than the width of the ranging area on the film screen. In the case of 5 mm and the number of photoelectric conversion cells on each array sensor is 50, the pitch of the photoelectric conversion cells projected on the film surface is about 100 μm. Here, the position and number of the photoelectric conversion cells used for distance measurement can be arbitrarily selected, and a plurality of divided distance measurement areas can overlap each other.
For example, if a ranging area is formed by setting several photoelectric conversion cells as one set, and the next ranging area is formed at a position shifted by one pitch of the photoelectric conversion cells, the ranging area can be formed almost continuously. You can say it. Of course, not only in the case where a plurality of ranging areas are provided but also in the case where one ranging area is arbitrarily selected within the range of the ranging area 41, the area can be selected with the positional accuracy of the photoelectric conversion cell unit. .

<Overall Description of Photometric System> Further, in FIG. 2, reference numeral 3 denotes a photometric element for dividing an object field into a plurality of areas and performing photometry, and is composed of, for example, an SPD (silicon photodiode). Further, as shown in FIG. 3, the photometric element 3 has a finder screen.
The image formed on the image 25 is mounted at a position where the image is re-imaged on the photometric element 3 by the photometric lens 27 via the pentaprism 26, and the entire screen of the object scene is
The image is formed on the entire surface.

As shown in FIG. 5, the photometric element 3
The current is proportional to the incident light intensity and is input to the photometric circuit 4 for each area. The photometric circuit 4, and logarithmic compression after converting the current from the photometric element 3 into a voltage, further reading aperture F value of the imaging lens (hereinafter referred to as F ₀₎ F ₀ 3A on the basis of an output from the determination circuit 5 ~
An absolute luminance value (hereinafter, referred to as a BV value) in each area of 3E is calculated. The output of the photometry circuit 4 is input to an exposure calculation circuit 6, and the output of the distance measurement circuit 2 is input to a subject discrimination circuit 7 and a main subject luminance calculation photometry circuit 8.

The subject discriminating circuit 7 discriminates a main subject by a method described later, and outputs the main subject information as a result to the main subject luminance calculating circuit 9. In the main subject luminance calculation photometry circuit 8 calculates the photometric output based on the output of the distance measuring circuit 2 and F ₀ determination circuit 5, and outputs the result to the main subject luminance calculation circuit 9. The main subject brightness calculation circuit 9 calculates the brightness of the main subject based on the main subject information and the calculation result of the photometry circuit 8 for calculating the main subject brightness,
The result is output to the exposure calculation circuit 6.

The exposure calculation circuit 6 calculates exposure value information for obtaining an appropriate exposure amount based on information from the photometry circuit 4 and the main subject luminance calculation circuit 9 according to an algorithm as shown in FIG. . The exposure control circuit 10
Based on the exposure value information from the exposure calculation circuit 6, the shutter
The exposure 11 and the aperture 12 are controlled so as to have predetermined exposure values.

 Next, a circuit constituting the photometric system will be described in detail.

<Subject Discrimination Circuit 7> The operation of the subject discrimination circuit 7 will be described with reference to a first example of FIG. 6A.

FIG. 6A is a diagram in which a subject in the field of view and the distance measurement area 41 are overlapped. First, the photographer puts the main subject 61 into the ranging area 41 in order to focus on the main subject 61, and half-presses a shutter release button (not shown). Then, the power of the camera is turned on, and the output signal from the ranging element 1 is input to the ranging circuit 2. In this case, the signal from the distance measuring element 1 is as shown in FIG. 7 (a). That is, FIG. 7A shows contrast information in the distance measurement area 41 corresponding to points A to B in FIG. 6A. The distance calculation, that is, the calculation of the defocus amount, is performed by the well-known 1
This is performed by calculating a relative shift amount between two outputs from the pair of CCD array sensors 1-1 and 1-2. Therefore, a pair of contrast information from each of the array sensors 1-1 and 1-2 is required for distance measurement, but one is omitted for simplicity because two pieces of contrast information are not required for discriminating a subject. .
Of course, the calculation may be performed using both of the two outputs.

The distance measuring circuit 2 has a distance measuring area as shown in FIG.
The contrast information in 41 is output to the subject determination circuit 7. The subject discriminating circuit 7 discriminates the main subject based on the contrast information as follows.

The area from the point A to the point C 'in FIG. 7A corresponds to the background in the object scene. Normally, the background has higher luminance than the main subject, so that the output is relatively high. The area from the point C 'to the point D' corresponds to the main subject in the field,
The output is relatively low due to the low brightness.
Since the area from point D 'to point B corresponds to the background in the scene, the output is high again. In such a case, the main subject corresponds to an area from the point C to the point D in the distance measurement area 41, and therefore, the object determination circuit 7 determines the area as the main object.

 Next, a second example is shown in FIG.

FIG. 6 (b) is a diagram showing the object within the field of view and the distance measurement area 41 superimposed. It is assumed that the photographer first presses a shutter release button (not shown) halfway in a framing state as shown in FIG. 6B. At this time, the subject relatively close to the photographer is
Two subjects, 62a and a subject 62b which is relatively far away, are included. Output signals from a pair of CCD array sensors 1-1 and 1-2 constituting the distance measuring element 1 are input to the distance measuring circuit 2. In this case, the signal from the distance measuring element 1 is approximately the seventh.
These are as shown in FIGS.

Here, FIG. 7 (b) shows the distance measuring element 1-1 shown in FIG.
7 (c) is an output signal from the distance measuring element 1-2 shown in FIG. In (b), the region from point A to point E 'is the background portion, the region from E' to F 'is the portion corresponding to the subject 62a, F' to G 'is the background portion, and G' to H 'is the background portion. Portions corresponding to the subject 62b, H 'to B, are background portions. The same applies to (c).

The distance measuring circuit 2 determines the region other than the background portion from the waveforms of FIGS. 7 (b) and 7 (c), that is, E 'to F' and G 'to H' in (b) and E "in (c). F "and H" from G "are extracted, and it is determined that there are two subjects.
Next, it is determined which of E'-F 'and E "-F" are the outputs of the CCD array sensors 1-1 and 1-2, respectively. Calculate the defocus amount. The same calculation is performed on the subject 62b, and as a result, the defocus amount of the subject 62b is obtained. Then, the distance measurement circuit 2 outputs the size and position of these objects in the distance measurement area, the defocus amount, the contrast information, and the like to the object determination circuit 7 as object information.

The subject discrimination circuit 7 selects a main subject based on the information. As a selection method, for example, the closest subject is preferentially selected.

A subject near the center is selected with priority.

The subject closest to the previous distance measurement value is preferentially selected.

The subject with the smallest defocus amount is preferentially selected.

Prioritize and select subjects with high contrast.

A subject with low contrast is preferentially selected.

A low-luminance subject is preferentially selected.

A high-luminance subject is preferentially selected.

Alternatively, these means are used in combination.

And the like, but are not limited to these.

Here, the detailed procedure of the subject determination circuit 7 will be described in the eighth.
This will be described with reference to the drawings.

In step S1, a contrast signal Cm (1 to n cells) is read from each photoelectric conversion cell of the CCD array sensor 1 for each cell. In step S2, the variable m is set to 1 and k is set to 0. In step S3, calculates the ΔCm = Cm ₊₁ -Cm, ΔCm is determined whether [Delta] C _TH or more at step S4, if a negative determination process proceeds to step S6, or m = 1 or DerutaCm _-1 is [Delta] C _TH more Is determined. If step S6 is denied, the process proceeds to step S10, and if affirmative, the process proceeds to step S8, where 1 is added to k, and in the next step S9, Cs
(K) is set to Cs (m), and the process proceeds to step S10.

That is, as shown in FIG.
If changes C ₁ ... C ₃ ~C _9, when m = 5, the difference [Delta] C ₅ between C ₆ and C ₅ obtained in step S3 proceeds to step S6 is less than [Delta] C _TH, further, previous When m = 4, the difference ΔC ₄ between C ₅ and C ₄ obtained in step S ₃ is equal to or more than ΔC _TH , so step S 6 is affirmative, k becomes 1 in step S 8, and the start of the subject in step S 9 Let Cs (5) be a contrast signal indicating a break between the two.

On the other hand, if step S4 is affirmed, the process proceeds to step S5,
Or DerutaCm _-1 is [Delta] C _TH or more, or m is determined whether 1. If affirmed, proceed to step S10; if denied, step S10
In step 7, Ce (k) is set to Ce (m), and the flow advances to step S10.

That is, when m = 7, the difference ΔC ₇ between C ₈ and C ₇ obtained in step S4 is equal to or more than ΔC _TH and the process proceeds to step S5. Further, when m = 6, the difference ΔC ₇ is obtained in step S4. Since the difference ΔC ₆ between C ₆ and C ₇ becomes smaller than ΔC _TH , step S5 is denied, and in step S7, the contrast signal indicating the end break of the subject is Ce (7).

In step S10, 1 is added to m, and in step S11, it is determined whether m is n. If denied, return to step S3 again,
Repeat the same procedure.

When step S11 is affirmed, that is, when the processing for the outputs of all the photoelectric conversion cells is completed, the process proceeds to step S12, and it is determined whether or not k is 0. If yes, step
In S13, the entire distance measurement area is determined to be a subject, and the process proceeds to return. If step S12 is negative, the process proceeds to step S14, and the BV value of the area determined to be the subject is calculated by the following equation.

Here, τ: accumulation time of each photoelectric conversion cell X: coefficient for compensating the loss of the optical system. That is, in the case of FIG. 8 (b), C ₅ + C ₆ + C ₇ is X ·
The value obtained by multiplying by τ and dividing by (C ₇ −C ₅ ) becomes the BV value of the main subject. For example, when there are two regions having contrast differences, k = 2, and the BV values are respectively determined based on the contrast signals between the starting point and the ending point of the main subject determined when k = 1 and k = 2, respectively. Is calculated.

On the other hand, in this step S14, the defocus amount is calculated using the contrast signal between Cs (5) and Ce (7). Thereafter, the process proceeds to step S15, where a main subject is selected from predetermined conditions. When k is 1, the region from Cs (m) to Ce (m) determined in steps S19 and S7 is unconditionally determined as the main subject, and when k is 2 or more, it is determined in step S14. The main subject is selected from the BV value of each area. For example, a low luminance area is selected.

According to such a method, a subject that satisfies the above condition is prioritized to be determined as a main subject, so that accurate determination can be made regardless of the number of subjects output from the distance measurement circuit 2. . When there are a plurality of subjects that satisfy the above condition within a certain range, a plurality of subjects may be selected.

<Main subject luminance calculating photometric circuit 8> Next, the main subject luminance calculating photometric circuit 8 will be described.

The main subject luminance calculation photometry circuit 8 divides the distance measurement area 41 shown in FIG. 6 into a plurality of areas and performs photometry, and receives a signal from the distance measurement circuit 2. From the distance measuring circuit 2, a pair of CCD array sensors 1-
The output value Z and the accumulation time t of each of the photoelectric conversion cells 1 and 1-2 are read. Then, an absolute luminance value for each photoelectric conversion cell is obtained by multiplying a value Z / t obtained by dividing the output value Z by the accumulation time t by a predetermined coefficient X for compensating for the loss of the optical system. In this case, the number of divisions of the divided photometry is equal to the number of photoelectric conversion cells, and the area is obtained by projecting the total area of the photoelectric conversion cells arranged on the array sensor onto the object screen.

<Main subject luminance calculation circuit 9> Next, the main subject luminance calculation circuit 9 will be described.

The main subject luminance calculation circuit 9 receives signals from the main subject luminance calculation photometric circuit 8 and the subject determination circuit 7. First, how the main subject is distributed in the distance measurement signal 41 is detected based on a signal from the subject determination circuit 7. For example, it is assumed that the main subject is determined to be the subject 62a by the subject determination circuit 7 on the screen as shown in FIG. At this time, the main subject luminance calculation circuit 9 sends the subject 62a
Is transmitted.

More specifically, the outputs E 'to F' and E "to F" of the distance measuring element 1 corresponding to the subject 62a are output from each CCD array sensor 1-.
It is information indicating which part of the output is 1-2. In this case, for example, a number may be assigned to each photoelectric conversion cell of the array sensors 1-1 and 1-2 shown in FIG. 4 and the number may be output.

Next, the main subject brightness calculation circuit 9 reads the absolute brightness value of each photoelectric conversion cell corresponding to the subject 62a from the main subject brightness calculation photometry circuit 8. If the number of the corresponding photoelectric conversion cells is l, it means that 1 luminance information has been obtained at this time. Here, the contrast information of the pair of CCD array sensors 1-1 and 1-2 outputted from the distance measuring circuit 2 is obtained by re-imaging light beams passing through different areas of the exit pupil of the photographing lens. Because
Although the addresses of the photoelectric conversion cells corresponding to the subject 62a are different, it is considered that the luminance information is the same. Therefore, in this case, the CCD array sensor 1-
It is only necessary to use one of the luminance information 1 and 1-2. Of course, both may be averaged and used.

The l pieces of luminance information obtained in the manner described above, obtaining the photometric value BV _sp of the main object. To find it, simply take the average of l pieces.

The information near the center of the subject is weighted and averaged.

The information on the low luminance side is weighted and averaged.

The information on the high luminance side is weighted and averaged.

The shoulder portion (edge portion) of the output is cut and the information only in the vicinity of the center is averaged.

Alternatively, these means are used in combination.

And the like, but are not limited to these.

As described above, the main subject luminance calculation circuit 9 measures the light only in the region where the subject exists based on the subject position information from the distance measurement region, so that the subject can be accurately measured regardless of the size of the subject. Value can be obtained. Further, if the main subject luminance calculation circuit 9 performs the photometry of the subject every time the distance measurement solution circuit 2 performs the distance measurement, the photometry area changes in a variable manner according to the movement of the subject, so that the subject Can also cope with the case where the position changes with time.

<Exposure Calculation Circuit 6> Next, the exposure calculation circuit 6 will be described. When the main subject luminance calculation circuit 9 obtains the photometric output BVsp of the main subject area, the exposure calculation circuit 6
Using the photometric output from the photometric circuit 3 for exposure calculation, an appropriate photometric output for the entire screen is obtained according to the procedure shown in FIG.

First, in step S11, the maximum luminance value in the photometric areas 3A to 3E is substituted for BVmax, and the minimum luminance value is substituted for BVmin. Next, BVmax−BVmin is calculated, and if these are determined to be 2 or less in step S12, BVsp is substituted for BVans as the photometric output of the entire screen in step S16. BVmax−BV
If min is greater than 2, the process proceeds to step S13, where BVma
It is determined whether x-BVsp is 1 or less. Where BVmax−
If BVsp is 1 or less, it is determined that the subject is whitish or bright, and the process proceeds to step S17 to place the BVsp such that the photometric value of the subject is emphasized and the background on the low-luminance side is also fitted. Is assigned to the exposure value information BVans. Here, the weighting ratio of BVsp: BVmin is 2: 1.

If BVmax-BVsp is greater than 1, step S14
To determine whether BVsp−BVmin is 1 or less. If BVsp−BVmin is 1 or less, it is determined that the subject is dark or dark, and the step S18 is performed so that the photometric value of the subject is emphasized and the background on the high luminance side is also exposed. Then, the average value obtained by weighting BVsp is substituted into BVans. Here, the weighting ratio of BVsp: BVmax is 2: 1.

When BVsp−BVmin is greater than 1, the screen state is as follows. In other words, this is a case where the maximum luminance of the background is larger than 1 in the BV value and the minimum luminance side is smaller than 1 with respect to the luminance value of the subject. In such a case, it is difficult to fit the entire screen within the latitude of the film.
s = BVsp.

Note that the numerical value used for determining the high luminance limit value and the luminance difference of the subject, the average ratio of weighting, and the like are not limited to the above numerical values.

In the above embodiment, the output from the distance measuring circuit 2 is used for the photometric calculation in the main subject luminance calculating photometric circuit 8, but the present invention is not limited to this, and the output is calculated using the output from another photometric element. May be. The photometric element in this case may be any element that can output the photometric value of the area corresponding to the position and size of the subject indicated by the subject determination circuit 7.

Further, in the above embodiment, the method of determining the main subject in the case where the natural focus detection is performed is described. However, even when the automatic focus detection is not performed, the distance measuring element 1 is determined.
By reading the output from the camera as photometric information, the main subject can be determined from the contrast information and the like. In this regard, the main subject may be determined based on the method of the first example of the operation of the subject determining circuit 7.

-Second Embodiment-In this second embodiment, at the time of focus detection, the distance measurement area 41 is divided into seven areas a to g as shown in FIG. 10, and the defocus amount of each area is obtained. The driving signal of the photographing lens is calculated as follows. That is, the subjects in each area are grouped based on the defocus amount of each area, one group that is expected to include the subject to be focused is selected, and the defocus amount of the area belonging to the group is selected. The final defocus amount is obtained based on In the photometric calculation, the luminance of the main subject is obtained from the photometric output of each photoelectric conversion cell in the area to which the finally selected group belongs.

 This will be described in detail with reference to FIGS. 10 to 13.

FIG. 10 is a diagram in which a subject in a field of view and a distance measurement area 41 are overlapped. As shown in the figure, the distance measurement area 41 further includes 41a
It is divided into seven regions of up to 41 g.

FIG. 13 is a flowchart showing the second embodiment,
It is executed by a microprocessor (not shown) or the like.

First, the photographer half-presses a shutter release button (not shown) in a framing state as shown in FIG. At this time, the distance measurement area 41 includes two subjects, a subject 62a relatively close to the photographer and a subject 62b relatively far from the photographer. In step S21, the distance measuring circuit 2
Has a pair of CCD array sensors 1-1 and 1-2 of the distance measuring element 1.
, Ie, a contrast signal. In this case, the signal from the distance measuring element 1 is approximately as shown in FIG. Here, FIG. 11 (a) shows an output signal from the distance measuring element 1-1 shown in FIG. 4, and FIG. 11 (b) shows an output signal from the distance measuring element 1-2 shown in FIG. It is.

Next, in step S22, the distance measurement circuit 2 applies a pair of contrast signals to the areas a to g in the distance measurement area 41 shown in FIG. 10 as shown in FIGS. 11 (a) and 11 (b). The regions are divided into regions 73a to 73g and 73a 'to 73g', respectively. 73a and 73a ', 73b and 73b', 73c and 73c '... 73g and 73
By performing a comparison operation on g ′, an area a in the distance measurement area 41 is obtained.
Defocus amount De (a) to De in each of the regions
(G) is obtained. Further, in step S23, distance information D (a) to D (g) of each area is calculated from the obtained defocus amount of each area and the current focus position of the photographing lens. The focus position of the photographic lens is obtained by monitoring the amount of movement of the lens from the ∞ position or by attaching a lens encoder or the like and outputting a signal corresponding to the focus position. FIG. 12 shows the defocus amount in each of the regions a to g.

Next, in steps S24 and S25, the main subject is determined by the subject determining circuit 7 in FIG. 2 based on the seven pieces of distance information. First, among the seven pieces of distance information, those having the detected distances closer to each other are grouped. As a criterion for the closeness of the distance, a certain fixed value may be used, or the value may be changed in proportion to the depth of field. Also, it is assumed that the regions to be grouped are adjacent to each other. For example,
In FIG. 12, they are grouped into a, b, c group, d, e group, and f, g group. The areas grouped in this way are regarded as subjects, and a main subject is determined and selected from the following from among them.

Select the closest distance.

The focus detection value at the center is preferentially selected.

The one closest to the previous focus detection value is selected.

Select the one with the smallest defocus amount.

And the like, but are not limited to these.

In this way, when the optimum group to be used for focus adjustment is obtained according to the procedure of FIG. 13, the main subject luminance calculation circuit 9 executes the photometry output for each photoelectric conversion cell sent from the photometry circuit 8 as described above. Then, the brightness value BVsp of the main subject is calculated. Thereafter, the exposure calculation circuit 6 calculates a proper exposure value in the same manner as described above.

G. Effects of the Invention According to the present invention, the luminance of the main subject is calculated by dividing the specific area in the object field into small pieces and performing photometry to calculate the luminance of the main subject and the exposure value. Since the proper exposure value of the entire screen is calculated from the photometric output of the photometric element, the exposure amount can be more finely controlled.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 9 illustrate the first embodiment, and FIG.
FIG. 3 is a block diagram of a multi-photometry device, FIG. 3 is a diagram showing an optical system path of a single-lens reflex camera, FIG.
FIG. 5 is a front view for explaining the area division of the photometer for exposure calculation, FIG. 6 is a diagram for explaining the operation of the first embodiment, FIG. 7 is a waveform diagram of a contrast signal from the distance meter, FIG. 8A is a flowchart showing a procedure for selecting a main subject, FIG. 8B is a waveform diagram of a contrast signal, and FIG. 9 is a flowchart showing an exposure calculation procedure. FIGS. 10 to 13 illustrate the second embodiment.
FIG. 11 is an explanatory diagram of the operation, FIG. 11 is a waveform diagram of a contrast signal from a distance measuring element, FIG. 12 is a diagram showing a defocus amount for each focus detection area, and FIG. 9 is a flowchart illustrating a procedure for selecting a subject. 1: Distance measuring element 1-1, 1-2: CCD array sensor 2: Distance measuring circuit, 3: Photometry element 4: Photometry circuit, 6: Exposure value calculation circuit 7: Subject discrimination circuit 8: Photometry for calculating main subject brightness Circuit 9: main subject luminance calculation circuit 10: exposure control circuit, 41: distance measurement area (specific area) 62a, 62b: subject 101, 201, 301: first photometry means 102, 203, 303: second photometry means 103, 204: subject discrimination means 104, 205, 306: luminance Calculation means 105, 206, 207: Exposure calculation means 202, 302: Focus detection means 304: Grouping means 305: Selection means

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeyuki Uchiyama 1-6-3 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Works Co., Ltd. (56) References JP-A-1-202720 (JP, A) JP-A-61-194430 (JP, A) JP-A-62-59937 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03B 7/28 G03B 3/00

Claims (3)

(57) [Claims] A first signal output unit for dividing a field into a plurality of large areas and outputting a first signal corresponding to the intensity of light incident on each of the areas; and specifying the field. A second step of dividing the area into a plurality of small areas smaller than the divided area of the first signal output means and outputting a second signal corresponding to the intensity of light incident on each of the small areas;
And a signal output means for determining which of the small areas includes a main subject to be focused based on the second signal output from the second signal output means. Means for calculating the brightness of the main subject using at least the second signal output from the small area where the subject determined to be the main subject by the subject determining means is present; An exposure value calculating means for calculating an appropriate exposure value based on the luminance of the main subject calculated in step (a) and the first signal from the first signal output means. 2. The focus detection apparatus according to claim 1, wherein a focus detection operation is performed on a subject existing in the specific area based on the second signal output from the second signal output unit. Calculating means for extracting the position and size of the main subject to be focused in the scene based on the focus detection calculation result of the focus detection calculating means; A multi-photometer, wherein the position of the small area is determined. 3. Photometric means for dividing a field into a plurality of large areas to obtain a photometric output for each area; and a specific area of the field into a plurality of small areas smaller than the divided area of the photometric means. A signal output unit that outputs a photoelectric conversion signal corresponding to the luminance of a subject existing in each of the small areas, and m pieces (n> m) of n pieces of the plurality of small areas ) For each of the focus detection areas
A focus detection operation unit that performs a focus detection operation based on the photoelectric conversion signal to calculate m defocus amounts; and calculates a photometric value of each of the small areas based on the photoelectric conversion signal from the signal output unit. A small area photometric value calculation value means, grouping means for collecting the m focus detection areas into j groups (m> j) according to the defocus amounts of the areas, Selecting means for selecting one optimal group from which an image of a subject to be focused is formed; and selecting means among a plurality of photometric values calculated by the small area photometric value calculating means Brightness calculating means for calculating the brightness of the main subject using at least the photometric value corresponding to the area of the group selected in the step; and measuring the brightness of the main subject calculated by the brightness calculating means and the brightness from the photometric means. Multi-Pattern apparatus characterized by comprising an exposure value calculating means for calculating a proper exposure value based on the output.