JPH06138513A - Camera - Google Patents

Abstract

PURPOSE:To evaluate the luminance of a specified background and to obtain an appropriate photometric value by selecting a specified small area based on the output of the posture state of a camera and changing weighting based on luminance information. CONSTITUTION:The image of an object is formed on a photodetector for photometry 6 by an image-formation lens for photometry 5, and divided into 16 small areas so as to perform photometry. A part of the image of the object formed in the vicinity of a visual field mask 10 arranged in the vicinity of the intended image-formation surface of a photographing lens 1 is formed on a photodetector for detecting focus 14 by an image-formation lens for detecting focus 13 so as to detect the focus in the areas corresponding to five focus detecting visual fields. A posture discriminating switch 15 generates three kinds of signals such as normal position, release button upper position, and release button lower position signals in accordance with the posture difference of the camera. Five apertures are provided on the mask 10, and the image of the object formed in the vicinity of the aperture is divided into two images and formed on the photodetector 14 by the lens 13 so as to detect five points in a photographic image plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera having a photometric device which divides an object field into a plurality of areas for photometry.

[0002]

2. Description of the Related Art Hitherto, various photometric devices have been proposed in which an object scene is divided into a plurality of areas and a luminance signal for each area is used to provide a proper exposure on a photographing screen. Among them, Japanese Patent Laid-Open No. 56-52732 proposes to obtain proper exposure by performing posture detection. In this publication, a photometric element group capable of performing photometry by dividing a shooting screen (field of view) of a camera into a plurality of parts can be changed into an appropriate zone pattern according to an attitude state based on camera attitude information. The zone pattern is internally classified into a plurality of zones, and each zone is weighted. As a result, regardless of whether the camera is held horizontally or vertically with respect to the ground, it is possible to prevent insufficient exposure due to bright light such as the sky.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In 6-52732, the shape of the zone pattern changes depending on the posture state of the camera. However, the zone pattern is simply determined by the pose of the camera. Therefore, for example, when shooting a person with the camera held in the vertical position, even if the zones are simply weighted from the center of the shooting screen to the ground side, accurate metering is required without considering what is on the top side. You can't get the value. For example, if there is an aspect on the heaven side, it is better not to use the luminosity information on the heaven side, but if there is a relatively low-luminance object such as a mountain on the heaven side, the luminance information on the heaven side is also used. Should be used with some correction. Thus, there was still a problem with the evaluation of the position of the main subject and the brightness of the background.

[0004]

A field of view is divided into a plurality of small areas for photometry, the photometry means for detecting the brightness of the divided small areas, and the attitude state of the camera are detected to detect the posture of the camera relative to the ground. Attitude detecting means for outputting a signal for distinguishing whether the shooting attitude is horizontal or vertical position attitude, and selecting means for selecting a specific small area among the plurality of small areas based on the output of the attitude detecting means. By providing the brightness correction means for changing the weighting of the specific small area based on the brightness information of the specific small area selected by the selecting means, the brightness of the specific background can be adjusted while giving importance to the main subject. By evaluating, an appropriate exposure value can be obtained.

[0005]

1 to 15 are views showing a first embodiment of the present invention, and show a photometric device of a camera having five focus detection areas.

FIG. 1 is a view showing a divided shape of a photometric light receiving portion according to the first embodiment of the present invention, showing a state of being projected on a field. In the figure, S0 to S15 represent a plurality of light receiving small areas divided into 16 areas, and SA, SB, SC, S
D and SE represent the focus detection areas projected on the field like the photometric light receiving section.

FIG. 2 is a view showing the optical arrangement of the first embodiment of the present invention. In FIG. 2, 1 is a taking lens, 2 is a quick return mirror, 3 is a focusing plate, 4 is a penta roof prism, and 5 is for photometry. Imaging lens, 6 light receiving portion for photometry, 7 eyepiece lens, 8 pupil position, 9 sub-mirror, 13 focus detecting lens, 14 focus detecting light receiving portion, 16 film surface, 15 camera posture A posture determination switch for detecting the. In the present embodiment, a subject image formed on the focusing plate 3 by the taking lens 1 is formed on the photometric light receiving section 6 by the photometric imaging lens 5 and shown in FIG.
The light is divided into a plurality of small areas for photometry, and a part of the subject image formed near the visual field mask 10 arranged near the planned image forming surface of the photographing lens 1 is used as the focus detecting image forming lens 13. An image is formed on the focus detection light-receiving unit 14 to detect the focus of a region corresponding to the five focus detection fields shown in FIG. The attitude determination switch 15 is a mercury switch, and the position of the mercury enclosed in the glass tube changes according to the attitude difference of the camera, and the attitude of the camera is electrically changed to the normal position, the release button upper position, and the release button lower position. It generates three types of position signals.

FIG. 3 is an exploded perspective view of the focus detection optical system shown in FIG. 2. As shown in FIG. 3, five openings are provided in the field mask 10 arranged near the planned image forming surface of the taking lens 1. The subject image formed in the vicinity of the five openings is divided into two images by the focus detection imaging lens 13, and the two images are formed on the focus detection light receiving unit 14 to display 5 images in the photographing screen.
It is detecting points.

FIG. 4 is a block diagram showing the circuit configuration of the first embodiment of the present invention. In the figure, SPD0 to SPD15
1 are silicon photodiodes for photometrically measuring the light-receiving small areas S0 to S15 shown in FIG. 1, each of which is combined with an operational amplifier AMP and a compression diode DI. 16 luminance signals corresponding to the small area are generated. The AESW is a metering mode selection switch, which is so-called evaluation metering that allows the camera to automatically determine the appropriate exposure for the shooting screen, and spot metering that determines the exposure from the signal of only a specific area of the scene. One of the photometric modes is selected. Reference numeral 14 denotes a light receiving unit for focus detection in FIG. 3, and CCDA1 and CCDA2 to CCDE1 and CCDE2 are a pair of light receiving element rows corresponding to the five focus detection fields SA to SE in FIG. 1, respectively. The defocus amount is detected and output. AFSW is a focus detection point selection switch, and the five focus detection fields SA to SE in FIG.
The automatic selection mode in which the camera automatically determines the focus detection position suitable for the shooting screen according to the distribution state of the defocus amount of the object field, and the above five focus detection positions by the operator's intention. It is possible to select any of the optional modes for determining one of the above. HVSW32
Is a posture determination switch described above, which generates a signal by roughly dividing the posture of the camera into three states.

In FIG. 4, a photometric circuit AECKT17,
Photometric mode selection switch AESW18, focus detection point selection switch AFSW20, attitude determination switch HVSW32
Is connected to an internal data bus line BUS21 of the microcomputer and used for various controls. In FIG. 4, reference numeral 22 denotes a central processing unit CPU that processes various input signals described above by using programs stored in various memories and directs the operation of various control mechanisms, and 23 stores various programs. Read-only memory ROM, 24 is a random access memory RAM for a work area for calculation, 25 is a display control mechanism DPCNTL, and 26 is a shutter speed control mechanism ST
CNTL and 27 are general-purpose input ports PIO, respectively, which are internal data bus lines BUS of the microcomputer.
21 is connected. The CPU 22 executes the operation according to the program stored in the ROM 23 by accessing the RAM 24 by using the above-mentioned input signal,
DPCNTL25, STCNTL2 based on the calculation result
Display and control of shutter speed by 6
A signal for controlling the lens is output to O27.

Reference numeral 28 in FIG. 4 is a connector CNCT,
Communication between the camera and lens. 29 is a read-only memory L that stores information specific to the taking lens.
ROMs 30, 31 are a focus position control mechanism AFCNTL and a diaphragm control mechanism APCNTL for the photographing lens, respectively. LROM 29 and AFCN provided in the taking lens
The TL30 and APCNTL31 are connected to the PIO27 of the camera via the CNCT28, and the CPU of the camera
Is read out or the control mechanism is actuated in accordance with the instructions.

Next, the operation of the first embodiment of the present invention will be described with reference to FIGS.

5 to 7 are flowcharts of the first embodiment of the present invention. FIG. 5 shows a main routine, and FIGS. 6 and 7 show each subroutine. In addition, FIG. 8 and FIG.
FIG. 8 is a supplementary explanatory diagram of the subroutine of FIG. 7.

First, the main routine of FIG. 5 will be described.

In the camera, information corresponding to the brightness of the field, information on the defocus amount of each of a plurality of preset focus detection points, photometric mode selection information based on the will of the photographer, and focus detection points. The selection information is used to control the focus position control and the exposure control and display control by the shutter speed and aperture setting. There are other items to be handled by the main routine, such as the drive control of the quick return mirror, but here only the items related to the photometric device of the camera of the present invention are taken out, and other items are omitted for simplicity. .

In STEP 01, the outputs of the five paired line sensors 14 are calculated from the AFCKT 19 as five defocus amounts for focus detection.

At STEP 02, the focus detection point selection signal from the AFSW 20 and the defocus signal from the AFCKT 19 are fetched, and when the operator arbitrarily selects five focus detection points, a signal corresponding to the detection points is output. If the operator automatically selects the focus detection point of the camera, the focus detection point closest to the object distance is detected from the five defocus amount signals, and the signal corresponding to the focus detection point is output. It is a focus detection subroutine. Here, the focus detection point signal SEL is output.

In STEP 03, the defocus amount for focus adjustment is determined from the defocus amounts of the five focus detection points and the focus detection point signal SEL, and the AFCNTL 30 adjusts the focus of the taking lens.

In STEP 04, signals corresponding to the brightness of 16 small areas are fetched as digital signals.

STEP 05 corrects the signal fetched from the AECKT 17 on the basis of the information peculiar to the photographing lens fetched from the LROM 29, and outputs the luminance signal of the field corresponding to each small area, and further the focus detection signal STL and the photometry mode. It is a photometric calculation subroutine that performs a calculation determined based on the signal MODE, and outputs a photometric value E.

In STEP 06, the aperture and shutter time are determined from the photometric value E according to a program such as a photographing mode preset in the camera, for example, a shutter priority mode.

At STEP 07, when the shutter speed is set, the exposure information of the aperture value and the information of the photometric mode are displayed on the display device of the camera by the DPCNTL 25.

In STEP01 to STEP08, the series of photographing operations in the camera is completed, and the state returns to STEP02 to prepare for the next photographing operation.

Next, the photometric value calculation subroutine will be described.

At STEP 09, digital signals D0 to D15 corresponding to the luminances of the 16 small areas of the photometric sensors S0 to S15 output from the AECKT 17 are fetched.

In STEP 10, lens-specific information such as the open F-number of the photographic lens mounted, the focal length, the exit pupil position, and the peripheral light amount drop when the diaphragm is opened is fetched from the LROM 33.

In STEP 11, the photometric sensor S0 from AECKT is based on the lens-specific information in STEP 10.
Correction values δ0 to δ15 corresponding to 16 output signals of S15 to S15
Is determined and the luminance signal is determined by correcting the D0 to D15 fetched in STEP09. Regarding the determined luminance signal, the small area S0 has luminance signal V0, S1 has V1, S2 has V2 ...
... S15 corresponds to V15.

STEP 12 is a posture determination switch HVSW
Is a subroutine for weighting a part of the brightness signals of the 16 small areas according to the signal from the camera, that is, the brightness SC which is a part of the average brightness C of the peripheral area described later. It is for. Details will be described later.

In step 13, it is determined whether the focus detection signal SEL is one of the focus detection points corresponding to the above-mentioned focus detection areas SA to SE.

The STEP 14 classifies the 16 small areas into three medium areas, that is, a small area including the selected focus detection point, an area around the small area, and a peripheral area around the small area. The average brightness of the area is calculated and output.
The average luminance signal of each middle area is A, the average luminance signal of the small area including the focus detection point, B is the average luminance signal of the surrounding middle area, and C is the peripheral luminance signal of the surrounding middle area.
It shall be output as a. Further, the weighted peripheral luminance signal determined by the attitude difference photometric correction subroutine in STEP 12 is designated as Ce.

According to STEP 13, the leftmost distance measuring point (S
When A) is selected (AFSW = FA), the average luminance signals A, B, Ca, Ce of each middle area are output based on the following equation. Here, SC is a value determined in STEP12.

A = V3 B = (V1 + V8 + V9) / 3 Ca = (V0 + V2 + V4 + V5 + V6 + V7 + V10 + V11 + 3 (V12 + V13 + V14 + V15)) / 20 Ce = (V0 + V2 + V4 + V5 + V6 + V7 + V10 + S10 + V10 + S10 + V10 + V10 + V10 + V20)
When is selected (AFSW = FB), the average luminance signals A, B, Ca, Ce of each middle area are output based on the following equation. Here, SC is a value determined in STEP12.

A = V1 B = (V0 + V3 + V6) / 3 Ca = (V2 + V4 + V5 + V7 + V8 + V9 + V10 + V11 + 3 (V12 + V13 + V14 + V15)) / 20 Ce = (V2 + V4 + V5 + V7 + V8 + V9 + V10 + S10 / V10 + V9 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V20) FC) outputs the average luminance signals A, B, Ca, Ce of each middle area based on the following equation. Here, SC is a value determined in STEP12.

A = V0 B = (V1 + V2 + V5) / 3 Ca = (V3 + V4 + V6 + V7 + V8 + V9 + V10 + V11 + 3 (V12 + V13 + V14 + V15)) / 20 Ce = (V3 + V4 + V6 + V7 + V8 + V9 + V10 + V10 + V10 + V10 + V10 + V20)
When is selected (AFSW = FD), the average luminance signals A, B, Ca, Ce of each middle area are output based on the following equation. Here, SC is a value determined in STEP12.

A = V2 B = (V0 + V4 + V7) / 3 Ca = (V1 + V3 + V5 + V6 + V8 + V9 + V10 + V11 + 3 (V12 + V13 + V14 + V15)) / 20 Ce = (V1 + V3 + V5 + V6 + V8 + V9 + V10 + C10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V10 + V20 FE) outputs the average luminance signals A, B, Ca, Ce of each middle area based on the following equation. Here, SC is a value determined in STEP12.

A = V4 B = (V2 + V10 + V11) / 3 Ca = (V0 + V1 + V3 + V5 + V6 + V7 + V8 + V9 + 3 (V12 + V13 + V14 + V15)) / 20 Ce = (V0 + V1 + V3 + V5 + V6 + V7 + V5 + V6 + V7 + C9) To judge. MODE = EV
In the case of (evaluative photometry), the process proceeds to STEP16 and MODE.
≠ EV, that is, when MODE = PA (spot photometry), the process proceeds to STEP 19.

In STEP 16, since evaluation photometry is selected as the photometry mode, evaluation photometry is performed. S
Three average luminance signals A, B, C obtained by TEP14
By using all of the
0 is calculated by the following formula.

E0 = (2A + 3B + 5Ce) / 10 In the above equation, the average value is obtained by multiplying the three average luminance signals A, B and C by a coefficient without simply averaging them. This is the area of the small area including the focus detection point S
(A), the area of the middle region around it is S (B), and the area of the surrounding peripheral region is S (C), the area ratio of the three regions is S (A): S (B ): S (C) = 1: 3: 20, so if the coefficient is not multiplied, the area near the focus detection will be
This is to rectify the fact that the evaluation is made with extreme importance. In the following description, the calculation for obtaining E0 in the above equation is referred to as focus detection point weighted average photometry.

STEP 17 uses the average luminance signals A, B, Ca of the area obtained in STEP 14 and the difference B--A, Ca--B values of the average luminance signals to infer the scene situation and correct the exposure. This is a correction value calculation for selectively determining the value α.

In STEP 18, the exposure correction value α output from the correction value calculation is added to the focus detection point weighted average photometry E0 to perform automatic exposure correction, and the final evaluation photometry value E is obtained by the following equation. .

E = E0 + α In STEP19, the metering mode signal is MOD in STEP15.
When E ≠ EV, that is, MODE = PA, spot metering is selected as the metering mode, and therefore spot metering is performed. In spot photometry, only the average luminance signal A of the small area including the selected focus detection point obtained in STEP 14 is used, and this value is output as it is as the photometric value E. That is, it is the following formula.

E = A In this embodiment, as the area including the focus detection point, one small light receiving area including the focus detection point is selected in correspondence with the selection of the focus detection point. Therefore, the spot metering becomes the luminance signal itself of this small area for light reception.

At STEP 20, the process returns to the main routine.

As described above, in the photometric value calculation subroutine, when the evaluation photometry is selected as the photometry mode or the spot photometry is selected, the focus on the photometry area is linked with the selection of the focus detection point. By changing the degree or the classification of the photometric area, it is possible to perform an appropriate photometric value calculation that accepts the will of the photographer.

FIG. 7 is a posture difference photometric correction subroutine, and FIGS. 8 and 9 are supplementary explanatory diagrams of the posture difference photometric correction subroutine. Here, FIG. 8 shows the posture state of the camera and the HVS.
FIG. 9 shows the relationship with the W output, and FIG. 9 shows a photometric light receiving section corresponding to a small area obtained by dividing the field image of the camera into 16 areas in the camera posture state of FIG.

STEP 21 is a posture detection switch HVSW
From the signal H that the camera is horizontal to the ground,
One of three types of signals, namely, a signal VR indicating that the release button 17 side is in the vertical position in the top direction or a signal VL indicating that the release button 17 side is in the vertical position in the ground direction is received. FIG. 8A is a conceptual diagram showing the camera posture state when HVSW = VL, FIG. 8B is a conceptual diagram showing the camera posture state when HVSW = H, and FIG. 8C is a conceptual diagram showing the camera posture state when HVSW = VR. is there.

STEP 22 discriminates the HVSW signal received in STEP 21, and if the signal is VL, STEP 22
23, if the signal is H, proceed to STEP 24, and if the signal is VH, proceed to STEP 25.

In STEP 23, as shown in FIG.
When HVSW = VL, the brightness signals V12 and V15 of the regions S12 and S15 corresponding to the ground side of the field screen of the 16-division photometric light receiving unit are selected, and the average output VG is calculated.

In STEP 24, as shown in FIG.
When HVSW = VH, the luminance signals V14 and V15 of the regions S14 and S15 corresponding to the ground side of the field screen of the 16-division photometric light receiving unit are selected, and the average output VG is calculated.

In STEP 25, as shown in FIG.
When HVSW = VR, the luminance signals V13 and V14 of the regions S13 and S14 corresponding to the ground side of the field screen of the 16-division photometric light receiving unit are selected, and the average output VG is calculated.

In STEP 26, the average output VG calculated in STEP 23 and the area S1 not used for VG calculation
3. Brightness difference K1 and K2 from the brightness V13 and V14 of S14 is K1
= V13-VG, K2 = V14-VG.

In STEP 27, the average output VG calculated in STEP 24 and the area S1 not used for VG calculation
2. Brightness difference K1 and K2 from brightness V12 and V13 of S13 is K1
= V12-VG, K2 = V13-VG.

In STEP 28, the average output VG calculated in STEP 30 and the area S1 not used for VG calculation
2. Brightness difference K1 and K2 from brightness V12 and V15 of S15 is K1
= V12-VG, K2 = V15-VG.

In STEP 29, based on the difference K1 and K2 between the brightness of each of the two light-receiving portions on the top of the screen calculated in STEP 26 and the average brightness of the two light-receiving portions on the ground side of the screen, TABLE. The weighting factors x1 and x2 are obtained from 1.

In STEP 30, based on the differences K1 and K2 between the luminances of the two light-receiving portions on the screen top side calculated in STEP 27 and the average luminances of the two light-receiving portions on the ground side of the screen, TABLE. The weighting factors x1 and x2 are obtained from 1.

In STEP 31, based on the differences K1 and K2 between the brightness of each of the two light-receiving portions on the top of the screen calculated in STEP 28 and the average brightness of the two light-receiving portions on the ground side of the screen, TABLE. The weighting factors x1 and x2 are obtained from 1.

In STEP 32, Sc, which is a part of the average luminance signal C in the middle region of the outermost periphery, is calculated by the following equation using the weighting coefficients x1 and x2 calculated in STEP 29.

Sc = 3 (x1 * V13 + x2 * V14 + (4-
x1-x2) * (V12 + V15)) / 2 In step 33, the average luminance signal C in the middle area of the outermost periphery is calculated using the weighting factors x1 and x2 obtained in STEP35.
Sc which is a part of is calculated by the following equation.

Sc = 3 (x1 * V12 + x2 * V13 + (4-
x1−x2) * (V14 + V15)) / 2 In step 34, the weighting factors x1 and x2 obtained in step 36 are used to calculate the average luminance signal C in the middle peripheral region.
Sc which is a part of is calculated by the following equation.

Sc = 3 (x1 * V12 + x2 * V15 + (4-
x1−x2) * (V13 + V14)) / 2 STEP 35 returns to the photometric value calculation subroutine.

In the above-described embodiment, the individual brightness of the peripheral area located on the heaven side is compared with the average brightness of the peripheral area located on the ground side because the high-brightness object located on the heaven side (for example, the sky or the sun). ) Is effective in reducing the effect of. However, as another way of thinking, a method of comparing the brightness of the peripheral area located on the top side with a reference value, or a focus detection point selected from among a plurality of focus detection points (main subject existing area)
The method of comparing with the brightness of the area where is located is also effective.

[0062]

According to the present invention, the object scene is divided into a plurality of small areas for photometry, the brightness is detected, the attitude state of the camera is detected, and based on the output of the attitude detection, identification of the plurality of small areas is performed. By selecting the small area and changing the weighting of the selected small area on the basis of the brightness information of the small area selected by the selecting means. By evaluating, an appropriate photometric value can be obtained.

Further, a plurality of small areas for photometry are classified based on the focus detection areas selected by the focus detection means capable of performing focus detection on a plurality of areas, and based on weighting and posture detection in the classification. Since the photometric value was calculated by taking into consideration the weighting of the selected specific area, it is possible to obtain the proper photometric value that reflects the importance of the main subject by accurately determining the position of the main subject and evaluates the brightness of the specific background. You can

[Brief description of drawings]

FIG. 1 is a diagram showing a divided shape of a photometric light receiving unit according to an embodiment of the present invention.

FIG. 2 is a diagram showing an optical system of a camera according to an embodiment of the present invention.

FIG. 3 is a perspective view of a multi-point focus detection optical system according to an embodiment of the present invention.

FIG. 4 is a diagram showing a circuit configuration of a camera according to an embodiment of the present invention.

FIG. 5 is a flowchart of an embodiment of the present invention.

FIG. 6 is a flowchart of an embodiment of the present invention.

FIG. 7 is a flowchart of an embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a difference in posture of a camera.

9 is an explanatory view showing a state of a photometry area corresponding to the posture of the camera shown in FIG.

[Explanation of symbols]

6 Light receiving part for photometry S _{1 to} S ₁₅ Small area for photometry 15 Focus detection light receiving part 22 Central processing unit CPU 27 Attitude determination switch

Claims (3)

[Claims] 1. The field of view is divided into a plurality of photometric small areas,
A photometric means for detecting the brightness of the divided small areas; a posture detecting means for detecting the posture state of the camera and outputting a signal for discriminating whether the photographing posture of the camera is horizontal or vertical with respect to the ground; Selecting means for selecting a specific small area from among the plurality of small areas based on the output of the posture detecting means;
A camera provided with a brightness correction means for changing weighting of the specific small area based on the brightness information of the specific small area selected by the selecting means. 2. A focus detection unit configured to detect a focus in a plurality of areas within the object scene, and the object scene is divided into a plurality of small areas for photometry, and the brightness of the divided small areas is detected. A photometric means for detecting a posture state of the camera, and a posture detection means for detecting a posture state of the camera and outputting a signal for discriminating whether the photographing posture of the camera is horizontal or vertical with respect to the ground, and a focus detection area in the focus detection means. First selecting means for selecting, and second selecting means for selecting a specific small area from the plurality of small areas based on the output of the posture detecting means, and for selecting by the second selecting means. A brightness correction means for changing the weighting of the specific small area based on the brightness information of the specific small area; and a classification determining means for performing a plurality of classifications based on the selection by the first selecting means, Classification and brightness correction procedure determined by the classification determination means A camera provided with a calculation means for calculating a photometric value by changing the weighting of the brightness of the plurality of small areas based on the weighting information of the step. 3. The brightness correction means compares the brightness of the selected specific small area with the brightness of another selected small area, and changes the weighting of the specific small area based on the difference. The camera according to claim 1 or 2, which is characterized.