JPH11125560A - Photometry device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photometry value in which the sensitivity distribution of a central important point photometry shows nearly concentric circles, even when other photometry modes and photometry elements are also used by performing weighting so that photometry sensitivity distribution is nearest to concentric circles. SOLUTION: A photometry part 21 divides a field to be photographed into a plurality of regions for performing the photometry, and outputs the photometry value of each region. An exposure operation part 27 averages a plurality of photometry values obtained by weighting to make photometry sensitivity distribution closest to concentric circles with specific radii set on a photography screen and hence calculates a final photometry value. More specifically, a weight decision part 26 decides what kind of weighting should be given to each photometry output from the photometry part 21 according to information from a focus detection part 22, a region selection part 23, or the like. Then, the exposure operation part 27 performs a weighting operation of the photometry value corresponding to the output of the photometry part 21 and the weight decision part 26, and calculates the final photometry value. The weight decision part 26 and the exposure operation part 27 are realized by operation by a 1-chip microprocessor 31.

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 measuring the brightness of a subject, and more particularly to a photometric device suitable for automatic exposure control of a camera.

[0002]

2. Description of the Related Art Conventionally, a photometric device of a camera is provided with photometric modes such as multi-segment photometry, center-weighted photometry, and spot photometry. The multi-segment photometry is a mode in which the object scene is divided into a plurality of portions and photometry is performed, and an appropriate exposure value is calculated from each photometric value. The center-weighted metering is a mode in which the central part of the scene is literally metered. The spot metering is a mode in which a small portion of the object scene is spot-metered.

Some cameras have a plurality of built-in photometric modes, and the photographer can select the photometric mode according to his / her preference by using a switch or the like. In many of these cameras, a photometric element is also used in each photometric mode, and photometric values in a plurality of regions obtained from one photometric element are averaged to obtain photometric values corresponding to the respective photometric modes. It has become.

Further, as shown in FIG. 12, an apparatus disclosed in Japanese Patent Publication No. Hei 7-27152 includes a plurality of focus detection areas F1 to F.
3 and a plurality of photometric areas. The photometry area includes a first area A including the focus detection area selected from the six areas, a second area B surrounding the first area A, and a second area B.
Is divided into three regions of a third region C which is a peripheral region of
The photometric value is calculated by changing the weight of each of the divided areas.

[0005]

However, in the above-mentioned conventional photometry device for a camera, the center-weighted photometry mode in the photometry mode literally focuses on the central portion of the photographing screen, so that the sensitivity distribution Is preferably concentric with respect to the optical axis, but if the divided shape of the photometric element is not concentric, the sensitivity distribution may not be concentric and may cause inconvenience. .

In the device disclosed in Japanese Patent Publication No. Hei 7-27152, the sensitivity distribution of the center-weighted photometry may not be concentric due to the lack of consideration.

Accordingly, the present invention provides a photometric device capable of obtaining a photometric value such that the sensitivity distribution of the center-weighted photometric measurement is close to concentric, even when the photometric device is used in combination with another photometric mode. The challenge is to provide

[0008]

In order to solve the above-mentioned problems, an object of the present invention is to provide a photometric unit (2) which divides an object field into a plurality of regions, performs photometry, and outputs photometric values of each region.
1) and a circle having a predetermined radius set on the shooting screen,
The photometric device includes a photometric value calculation unit (27) that calculates a final photometric value by averaging a plurality of photometric values obtained by weighting such that the photometric sensitivity distribution is closest to a concentric circle.

According to a second aspect of the present invention, in the photometric device according to the first aspect, the photometric section (21) has a central photometric region (BV1) located within a boundary line along a predetermined radius and the predetermined radius. A photometric device comprising at least one spot photometric area (BV7, BV8) penetrating the area.

[0010] According to a third aspect of the present invention, there is provided a photometric unit (21) including a central photometric area located within a boundary line along a predetermined radius and at least one spot photometric area whose predetermined radius passes through the area. A focus detection section (22) for detecting a focus state of a plurality of focus detection areas of the object field; and an area selection section (23) for selecting one of the plurality of focus detection areas.
A weight changing unit (26) for changing a weight of a weighted average to the photometric region based on an output of the region selecting unit.
And a photometric value calculation unit (27) that calculates a final photometric value by weighting and averaging the output from the photometric unit based on the output of the weight change unit.

According to a fourth aspect of the present invention, in the photometric device according to the third aspect, the focus detection section (22) includes a focus detection area in an area corresponding to the spot photometry area. It is.

The invention of claim 5 is the invention of claim 3 or claim 4.
2. The photometric device according to claim 1, wherein the weight changing unit (26).
Is a photometric device characterized in that the weight of a spot photometric region corresponding to an unselected focus detection region is set lower than the weight of a spot photometric region corresponding to a selected region.

[0013] The invention of claim 6 is the invention of claims 3 to 5.
The photometric device according to any one of the above, further comprising a focus adjustment selection unit that selects whether to automatically or manually adjust the focus of the photographing lens, wherein the weight change unit outputs the focus adjustment selection unit The photometric device is characterized in that the weight is changed based on the following.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a photometric device for a camera according to an embodiment of the present invention.

The photometric unit 21 is a circuit for photometrically measuring the object scene using a light receiving element such as an SPD (silicon photodiode).
Output to As shown in FIG. 4, the photometry unit 21 has a structure in which the object field is divided into ten regions BV1 to BV10, the photometry is performed, and the respective brightness values can be output.

The focus detecting section 22 is capable of detecting the focus in the five focus detecting areas FA1 to FA5 shown in FIG. 4, and according to information from the area selecting section 23, one of the focus detecting areas FA1 to FA5. The focus state of the region is detected. The region selection unit 23 allows the photographer to arbitrarily select the focus detection regions FA1 to FA
5 is selectable.

The AF / MF switching section 24 is a section for outputting a signal for switching between automatic and manual focus adjustment of the photographing lens. For example, the AF / MF switching section 24 has a structure which can be arbitrarily selected by a photographer using an operation switch or the like. It has become. The lens driving unit 25 receives the information from the focus detection unit 22 and the AF / MF switching unit 24 and uses the photographic lens 1 shown in FIG.
Is driven to the in-focus position.

The weight determining section 26 gives what weight to each of the photometric outputs BV1 to BV10 from the photometric section 21 based on information from the focus detecting section 22, the area selecting section 23, and the AF / MF switching section 24. This is the part that decides. The exposure calculation unit 27 is a unit that performs weighting calculation of the photometric value according to the outputs of the photometric unit 21 and the weight determination unit 26, and calculates the final photometric value BVa. Note that the weight determining unit 26 and the exposure calculating unit 27 are realized by calculation by a one-chip microprocessor (hereinafter abbreviated as a microcomputer) 31.

The exposure controller 28 drives the mirror 2, the diaphragm 29 and the shutter 30 based on the output of the exposure calculator 27 to expose the film.

FIG. 2 is a block diagram showing an optical system according to the embodiment of the present invention. The light beam that has passed through the photographing lens 1 reaches the photographer's eye through the quick return mirror 2, the diffusion screen 3, the condenser lens 4, the pentaprism 5, and the eyepiece 6. On the other hand, a part of the light flux diffused by the diffusion screen 3 reaches the photometric element 9 through the condenser lens 4, the pentaprism 5, the photometric prism 7, and the photometric lens 8.

The quick return mirror 2 is a half mirror that transmits a part of the light beam, and the transmitted light beam is bent downward by the sub-mirror 10 so that the field mask 11, the field lens 12, and the separator lens 13 are moved. After passing through, the light enters the light receiving element 14 for focus detection.

FIG. 3 is a diagram illustrating the optical system of the focus detecting section 22 in more detail. The light beam that has passed through the photographing lens 1 is narrowed down to only a necessary light beam by the field mask 11, condensed by the field lens 12, and then imaged on each light receiving area of the focus detection light receiving element 14 by the separator lens 13. You. This focus detection method is a so-called phase difference detection method, in which a secondary image of an object field formed by a pair of separator lenses 13 provided for each focus detection area is transmitted to a focus detection light-receiving element 14. Each of the provided areas is caused to receive light by a pair of CCD sensors, and the focus state is detected from the shift amount of the output.

In the area FA1 at the center of the screen,
CCD sensors 1A and 1B for detecting a lateral shift amount;
It is a cross type provided with CCD sensors 1C and 1D for detecting the amount of displacement in the vertical direction.

FIG. 4 is a diagram showing the divided state of the light receiving element 9 in comparison with the object scene. The light receiving element 9 divides almost the entire surface of the object field into 10 parts for photometry, and each photometric value B
V1 to BV10 can be output. Here, the areas of BV6 to BV10 are equal, and
V1 has about seven times the area of each of these. BV
The shape of 1 is a shape along the circumference CW having a radius of about 6 mm (about 12 mm in diameter), which is an index of center-weighted photometry indicated by a dotted line, for an aperture size of 35 mm format of 36 mm × 24 mm. . The reason why the circumference on the top side is partially cut is to eliminate a high-brightness subject with a high probability of being located on the top side, such as the sky. However, regardless of whether the top side is cut or not, the present invention Applicable. Also,
The focus detection unit 22 can select and detect focus states of five focus detection areas FA1 to FA5 corresponding to BV6 to BV10.

FIG. 5A shows the photometric areas BV1, BV in FIG.
FIG. 13 is a simplified diagram showing a photometric sensitivity distribution with respect to a shooting screen when V6, BV9, and BV10 are used, and a photometric value is obtained by averaging with weights according to their area ratios.
FIG. 5B is a diagram showing the sensitivity distribution at that time by contour lines. As shown in FIG. 2, the photometry unit 21 performs photometry using the light flux diffused by the diffusion screen 3, so that the sensitivity does not immediately become 0 even at a position outside the photometry area, but rather slightly. The sensitivity goes down in an inclined form.

FIG. 6A shows a photometric sensitivity distribution with respect to a photographing screen when photometric values are obtained by averaging weighting according to the area ratio between the photometric regions BV1 and BV6 to BV10 in FIG. It is the figure which was simplified and shown. FIG. 6B is a diagram showing the sensitivity distribution at that time by contour lines.

FIG. 7 (a) uses the photometric regions BV1 and BV6 to BV10 of FIG. 4, and weights BV1, BV6, BV9 and BV10 according to their area ratios, and BV7 and BV8 in the figure. Simplifies the photometric sensitivity distribution for the shooting screen when the photometric value is obtained by averaging the photometric values on the circumference CW of a predetermined radius from the optical axis indicated by the dotted line so that the photometric sensitivity is equal to other circumferences. FIG. FIG. 7B is a diagram showing the sensitivity distribution at that time by contour lines. The predetermined radius is generally about 6 mm when the photographing screen is a 36 mm × 24 mm 35 mm film. By averaging with such weighting, the photometric sensitivity distribution is most concentric near the circumference CW of a predetermined radius serving as an index of center-weighted photometry, as indicated by K in FIG. Since the shape of the sensitivity distribution becomes close, good characteristics are obtained as the center-weighted photometry.

FIG. 8A shows a photographing screen when the photometric values are obtained by using the photometric regions BV1 and BV6 to BV7 and BV9 to BV10 of FIG. 4 and averaging them by weighting according to their area ratios. FIG. 3 is a diagram showing a simplified photometric sensitivity distribution. FIG. 8B is a diagram showing the sensitivity distribution at that time by contour lines. In this case, the photometric sensitivity distribution is
It does not become concentric from the optical axis X shown in FIG.
The center of gravity slightly shifts to X 'on the BV7 side. When FA2 corresponding to BV7 is selected as the focus detection area, the probability that the position where the main subject exists is shifted to the BV7 side is high. Probability also goes up.

FIG. 9 (a) shows the photometric sensitivity to the photographing screen when the photometric values are obtained by averaging weighting according to the area ratio of the photometric regions BV1, BV6, and BV8 to BV10 in FIG. It is the figure which showed distribution simplified.
FIG. 9B is a diagram showing the sensitivity distribution at that time by contour lines. In this case, the photometric sensitivity distribution is as shown in FIG.
Will not be concentric from the optical axis X shown in FIG. 7, but the center of gravity will be slightly shifted to X ″ on the BV8 side. If FA3 corresponding to BV8 is selected as the focus detection area, the main subject Is more likely to be shifted to the BV8 side, so having such a sensitivity distribution increases the probability of proper exposure.

FIG. 10 is a flowchart showing a program of the microcomputer 31. When the release button of the camera (not shown) is half-pressed, the power of the camera is turned on, and this program is executed. First, step S10
In step 1, the settings of the AF / MF switching unit 24 are read. Then, in step S102, it is determined whether the focus adjustment is automatic (AF) or manual (MF). In the case of manual (MF), the following values are set in w6 to w10 in step S103. substitute. w6 = a, w7 = b, w8 = b, w9 = a, w10 = a (1) Here, wi (i = 6 to 10) is the photometric area BVi (i).
= 6 to 10).
A is BV6 to BV when the area of BV1 is 1;
It is the area ratio of V10, and the values of BV6 to BV10 are all equal because the areas are equal. b is a value of a weighting constant that gives a weight such that the photometric sensitivity distribution at a predetermined radius from the optical axis becomes concentric as shown in FIG. The value of b can be obtained by simulation or the like from the area ratio or the like, but may be obtained by experiment.

If the focus adjustment has been set to automatic (AF), the flow advances to step S104 to read the settings of the area selection section 23 and determine which area has been selected as the focus detection area. If it is determined in step S105 that the selected area is FA2, the process proceeds to step S106, and the following values are substituted for w6 to w10. w6 = a, w7 = a, w8 = 0, w9 = a, w10 = a (2) In this case, the sensitivity distribution of the averaged photometric value is as shown in FIG.

Next, when it is determined in step S107 that the selected area is FA3, the process proceeds to step S107, and the following values are substituted for w6 to w10. w6 = a, w7 = 0, w8 = a, w9 = a, w10 = a (3) In this case, the sensitivity distribution of the averaged photometric value is as shown in FIG.

If the selected area is other than FA2 and FA3, that is, FA1, FA3 to FA5, the process proceeds to step S109, and the following values are substituted for w6 to w10. w6 = a, w7 = b, w8 = b, w9 = a, w10 = a (4) In this case, the sensitivity distribution of the averaged photometric value is as shown in FIG.

In step S110, focus detection is performed on a selected area among FA1 to FA5. Step S11
In step S1, if the focus adjustment is automatic (AF) by the setting of the AF / MF switching unit 24, step S1 is executed.
According to the result of step 10, the photographing lens 1 is driven to the focus position, and when the mode is manual (MF), the photographing lens 1 is not driven, and the direction of defocus is determined by a display function (not shown). Is displayed.

In step S112, photometry of the object scene is performed by the photometry unit 21, and photometric values of BV1 to BV10 are obtained. In step S113, w6 to w1 previously obtained
Based on 0 and the photometric value of each area obtained in step S112, the final photometric value B
Calculate Va.

[0036]

(Equation 1)

In general, when calculating a photometric value, a so-called apex method is used in which a value obtained by converting a photocurrent obtained from the light receiving element 9 in the photometric unit into a logarithm having a base of 2 is used. However, when the photometric values are weighted and averaged in the calculation of Equation 1, the photometric values are not logarithmically compressed.
This must be done with an exact numerical value proportional to the value of the photocurrent from the light receiving element 9. Therefore, when BVi is a logarithmic value, it is necessary to return the value to an exact value, perform the operation of Expression 1, and logarithmically compress the calculated value again.

In step S114, it is determined whether or not a release button (not shown) has been fully pressed. If the release button has been fully pressed, in step S115, the obtained photometric value BV is determined.
Based on a, the aperture 29 and the shutter 30 are controlled to expose the film, and if the film is not fully pressed, the process proceeds directly to step S116. In step S116, it is determined by the half-press timer whether a predetermined time has elapsed after the release of the half-press of the release. If the release is half-pressed or the timer is within the predetermined time, step S10 is executed.
Returning to step 1, the process is repeated, and if the timer has expired, the program ends.

According to this embodiment, there are the following various effects. (1) Even in a photometric device using a photometric element having a complicated divided shape, in the center-weighted photometric mode, the photometric sensitivity distribution is close to a concentric circle. (2) Even in the case of a divided photometric element in which the spot photometric region passes through a predetermined radius, the photometric sensitivity distribution becomes close to a concentric circle. (3) It is possible to obtain a photometric value having an optimal photometric sensitivity distribution according to the selected focus detection area. (4) When a focus detection area is provided in an area corresponding to the spot photometry area, a photometric value having an optimal photometric sensitivity distribution can be obtained. (5) By reducing the weight of the spot photometry area corresponding to the focus detection area that is not selected, it is possible to obtain a photometry value having an optimum photometry sensitivity distribution. (6) When focus adjustment is performed automatically / manually, a photometric value having an optimal photometric sensitivity distribution can be obtained.

Various modifications and changes are possible without being limited to the embodiment described above, and these are also within the equivalent scope of the present invention. For example, the division state of the divisional photometry is not limited to the one shown in FIG. 4, but may be a matrix-like photometric element as shown in FIG. In this case, the photometric area M indicated by oblique lines is averaged by a weight such that the photometric sensitivity on a circle having a predetermined radius from the optical axis indicated by L in the drawing is equal to the other circles. The photometric value may be obtained by using By averaging with such weighting, the photometric sensitivity distribution is most concentric near the circumference of a predetermined radius, which is a good characteristic for center-weighted photometry.

[0041]

As described above in detail, according to the present invention, even when a photometric element which is also used for another photometric mode is used, the shape of the finder index and the actual photometric sensitivity distribution become the same, A photometric device with less photometric error can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a photometric device for a camera according to the present invention.

FIG. 2 is a diagram showing an optical system of the photometric device according to the embodiment.

FIG. 3 is a diagram illustrating a configuration of a focus detection unit of the photometric device according to the embodiment.

FIG. 4 is a diagram showing a division state of divisional photometry of the photometric device according to the embodiment.

FIG. 5 is a diagram showing a photometric sensitivity distribution of the photometric device according to the embodiment.

FIG. 6 is a diagram showing a photometric sensitivity distribution of the photometric device according to the embodiment.

FIG. 7 is a diagram illustrating a photometric sensitivity distribution of the photometric device according to the present embodiment.

FIG. 8 is a diagram showing a photometric sensitivity distribution of the photometric device according to the embodiment.

FIG. 9 is a diagram showing a photometric sensitivity distribution of the photometric device according to the embodiment.

FIG. 10 is a flowchart illustrating an algorithm of the photometric device according to the embodiment.

FIG. 11 is a diagram illustrating a division state of divisional photometry of a photometric device according to another embodiment.

FIG. 12 is a diagram showing an example of a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 shooting lens 2 quick return mirror 3 diffusion screen 4 condenser lens 5 pentaprism 6 eyepiece 7 photometric prism 8 photometric lens 9 light receiving element 10 colorimetric light receiving element 11 field mask 12 field lens 13 separator lens 14 light receiving for focus detection Element 21 Photometry unit 22 Focus detection unit 23 Area selection unit 24 AF / MF switching unit 25 Lens driving unit 26 Weight determination unit 27 Exposure calculation unit 28 Exposure control unit 29 Aperture 30 Shutter 31 Microprocessor

Claims (6)

[Claims] 1. A photometric unit that divides an object field into a plurality of regions and measures the light, and outputs a photometric value of each region, and a photometric sensitivity distribution is best for a circle having a predetermined radius set on a shooting screen. A photometric device comprising: a photometric value calculating unit that calculates a final photometric value by averaging a plurality of photometric values obtained by weighting so as to approximate concentric circles. 2. The photometric device according to claim 1, wherein the photometric unit includes a central photometric area located within a boundary line along a predetermined radius and at least one central area having a predetermined radius passing through the area.
A photometric device comprising two spot photometric areas. 3. A central photometric region located within a boundary line along a predetermined radius and at least one central photometric region penetrating the region.
A photometry unit having two spot photometry regions; a focus detection unit that detects a focus state of a plurality of focus detection regions of an object field; and an area selection unit that selects one of the plurality of focus detection regions. A weight changing unit that changes the weight of the weighted average to the photometric region based on the output of the region selecting unit; andweighting and averaging the output from the photometric unit based on the output of the weight changing unit. A photometric device comprising: a photometric value calculation unit that calculates a final photometric value. 4. The photometry device according to claim 3, wherein the focus detection unit includes a focus detection area in an area corresponding to the spot photometry area. 5. The photometric device according to claim 3, wherein the weight changing unit assigns a weight of a spot photometric region corresponding to a focus detection region not selected to a spot photometric region corresponding to the selected region. A photometric device characterized by being lower than the weight of the photometric device. 6. The photometric device according to claim 3, further comprising: a focus adjustment selection unit that selects whether to automatically or manually adjust a focus of the photographing lens, The photometric device, wherein the weight changing unit changes the weight based on an output of the focus adjustment selecting unit.