JP4086367B2 - camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera for measuring light by dividing a photographing screen (field of view) into a plurality of small areas.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various cameras have been proposed in which an object scene is divided into a plurality of areas, and a proper exposure is given to a shooting screen using a luminance signal for each of these areas.
[0003]
For example, in Japanese Patent Application Laid-Open No. Hei 3-223281, a focus detection unit that divides a scene into a plurality of areas and detects the luminance of each of the areas, and can detect a plurality of the scenes independently. According to the selection of the focus detection area, the plurality of small photometry areas are grouped concentrically around the selected focus detection area, and each average luminance of the grouped areas is weighted with a predetermined weight. Cameras that calculate photometric values of the entire field have been proposed.
[0004]
In Japanese Patent Laid-Open No. 5-53169, the subject position in the object field is inputted by detecting the photographer's line-of-sight position or the like. There has been proposed a camera that groups into a plurality of patterns according to a division pattern that changes flexibly according to the position, and obtains a photometric value by weighting the average luminance of each group with a predetermined weight.
[0005]
By the way, in order to photograph a photographing field with an optimum exposure amount, the photometric sensor tends to be divided into multiple parts so as to obtain a large amount of luminance information from the field. For example, by using an area sensor such as a CCD as in the camera proposed in Japanese Patent Laid-Open No. 5-53169, it is possible to obtain an optimal divided photometry pattern for a subject.
[0006]
However, since the area sensor is a charge storage type sensor, there is a problem of responsiveness at the time of low luminance, and its price is expensive. For this reason, as the photometric sensor, those of the photodiode type are generally widely used.
[0007]
However, for this photodiode type sensor, increasing the number of divisions of the sensor section reduces the light receiving area of each divided small region, resulting in a decrease in the photometric ability of the photometric sensor at low luminance. It means inviting. Therefore, it is better to use a divided sensor having a certain size and number than a photometric sensor that can form an arbitrary number of fine divided patterns, using an area sensor consisting of a collection of sensors each having a minute size. It can be said that the sensor is generally easy to use from the viewpoint of low-luminance photometric capability and photometric calculation processing capability.
[0008]
On the other hand, in order to focus the photographic lens on the photographic subject, the camera performs a focus detection operation. Sensors that perform this focus detection also tend to be divided into multiple parts. For example, two area sensors are used, and the pixels of the area sensors are divided and correlated to each other, so that many of them in a photographing screen can be obtained by a known phase difference detection method. It is possible to detect the focus of the area.
[0009]
The contents proposed so far regarding the relationship between the photometry area and the distance measurement area include the camera proposed in Japanese Patent Laid-Open No. Hei 3-223821, and the number of focus detection areas is considerably larger than the number of photometry areas. Because of the small amount, it was possible to arrange each focus detection area at almost the center of gravity of each small photometric area. Therefore, if a photometric calculation such as a weighting calculation is performed based on the determination that the photometric area including the focus detection area where the focus detection (ranging) operation should be performed is a photometric area corresponding to the main subject position, it is almost appropriate. I was able to get a good exposure.
[0010]
However, if the number of focus detection areas can be configured to be equal to or more than the number of small photometry areas, the focus detection area where the focus detection operation of the main subject should be performed is almost the center of gravity of the photometry small area. Therefore, it is difficult to determine one small photometric area corresponding to the main subject position which is a reference for performing photometric calculation. In other words, this means that accurate exposure cannot be determined for the photographic subject. Such an optical discrepancy, which can be referred to as a parallax between the focus detection area and the photometry small area, is caused by a difference in sensor layout shape between the focus detection sensor and the photometry sensor itself, or a problem in optical configuration.
[0011]
[Problems to be solved by the invention]
In response to this problem, when the focus detection region on the boundary between the two photometric subregions is selected as the focus detection region to be focus-detected, the applicant of the present invention performs respective photometry for the two photometric subregions. We have proposed a camera that performs two weighting operations centered on a small area and determines the exposure value from both operations.
[0012]
However, with this method, the exposure value is averaged with the photometric calculation value that places importance on the luminance of the light metering small area that is not related to the original main subject position, and is the maximum with respect to the original main subject luminance. There is a possibility that the effect of the weighting calculation for performing the weighting will be reduced.
[0013]
In addition, the applicant of the present invention has determined the amount of defocus in the focus detection area on the boundary between the two selected small photometry areas and the defocus amount in the two focus detection areas corresponding to the small photometry areas divided by the boundary. There has also been proposed a camera that performs weighted photometry calculation by comparing a focus amount and selecting a small photometric region corresponding to the focus detection region that indicates the defocus amount closest to the defocus amount of the selected focus detection region.
[0014]
However, in this method, it is necessary to perform a heavy calculation in terms of software such as comparing the defocus amount, and the defocus amount cannot be calculated because of low luminance or low contrast in the region where the focus detection operation is to be performed. In this case, there is a disadvantage that the photometric calculation does not operate correctly.
[0015]
Therefore, the present invention provides only a luminance signal of a relatively small number of divisional photometric subareas even when the focus detection area where the focus detection operation of the main subject should be performed in the finder optical system is arranged near the boundary of the photometric subarea. An object of the present invention is to provide a camera that can perform optimum photometry with the main subject as the center and taking into consideration the entire object field.
[0016]
[Means for Solving the Problems]
  In order to achieve the above object, in the present invention,A photometric sensor that measures the luminance in a plurality of photometric areas using a part of the luminous flux from the subject, and a plurality of focal points that use a different luminous flux from the subject toward the photometric sensor. A focus detection sensor capable of performing focus detection in the detection region, and a focus detection region selecting means for selecting a focus detection region for performing a focus detection operation from a plurality of focus detection regions;Focus detection area selected by the focus detection area selection meansMain metering area based onControl means to determineWhenHaveTo do. Here, the plurality of focus detection areas include a focus detection area corresponding to each photometry area on a one-to-one basis and a focus detection area located on the boundary between the plurality of adjacent photometry areas in the photographing screen. Contains. When the focus detection area selected by the focus detection area selection means has a one-to-one correspondence with the photometry area, the control means sets the corresponding photometry area as the main photometry area and is selected by the focus detection area selection means. If the focus detection area is located on the boundary, the light measurement area having the lowest luminance among the plurality of light measurement areas forming the boundary is set as the main light measurement area.

[0017]
  For example, when the selected focus detection area is located on the boundary between a plurality of adjacent photometry areas, theseThe lowest detected luminance in the photometric areaPhotometryregionAs the main metering areaChoiceIs done. AndThe weighted photometric calculation may be performed by giving the maximum weight to the detected luminance in the main photometric area.
[0018]
  ThisBased on the focus detection area selected by the focus detection area selection means,Metering area used as the basis for metering calculation(Main metering area)Therefore, it is possible to obtain an appropriate exposure result using a photometric sensor with a relatively small number of divisions.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
1 to 6 show a single-lens reflex camera according to the first embodiment of the present invention. In this figure, reference numeral 1 denotes a photographic lens, which is shown as a two-lens lens for the sake of convenience in this figure, but actually comprises a larger number of lenses. Reference numeral 2 denotes a main mirror which is obliquely installed in the photographing optical path in the finder system observation state and is moved away from the photographing optical path in the photographing state.
[0020]
Reference numeral 3 denotes a sub-mirror that reflects the light beam transmitted through the main mirror 2 toward the lower side of the camera body. Reference numeral 4 denotes a shutter.
[0021]
A photosensitive member 5 is composed of a silver salt film, a solid-state imaging device such as a CCD or MOS type, or an imaging tube such as a vidicon.
[0022]
Reference numeral 6 denotes a focus detection device, which includes a field lens 6a, reflection mirrors 6b and 6c, a secondary imaging lens 6d, a diaphragm 6e, a line sensor 6f composed of a plurality of CCDs, and the like disposed in the vicinity of the imaging surface. .
[0023]
  The focus detection device 6 of the present embodiment uses a known phase difference method, and as shown in the viewfinder field diagram of FIG. 3, a plurality of focus detection areas F0 to F8 (focus points) in a shooting screen (field of view). detectionArea mark70 to 78), the focus state can be detected.
[0024]
Reference numeral 7 denotes a focusing plate disposed on the planned imaging plane of the taking lens 1, and 8 denotes a finder optical path changing pentaprism.
[0025]
Reference numerals 9 and 10 denote an imaging lens and a photometric sensor for measuring the luminance of each object in the photographing screen. The imaging lens 9 is connected to the focusing plate 7 and the photometric sensor 10 via a reflected light path in the pentaprism 8. It is related to conjugation.
[0026]
Here, as shown in FIG. 3, the photometric sensor 10 has 19 small pixels that can detect the luminance of each small area (photometric small area) that divides the photographing screen into 19 areas from S0 to S18. This is a 19-divided sensor composed of area sensors (SPC-0 to SPC-18).
[0027]
Here, as shown in FIG. 3, the focus detection areas F0, F2, F4, F6, and F8 are arranged so as to be located substantially at the center of gravity of the photometric small areas S3, S1, S0, S2, and S4, respectively. The focus detection areas F1, F3, F5, and F7 are arranged so as to be positioned on the boundaries between the photometric small areas S3-S1, S1-S0, S0-S2, and S2-S4, respectively. Note that the boundary lines of each photometric small area in the viewfinder field shown in FIG. 3 are virtual lines obtained by projecting the division state of the photometric sensor onto the viewfinder, and these lines cannot be seen in an actual viewfinder. .
[0028]
In addition, an eyepiece lens 11 is disposed behind the exit surface of the pentaprism 8 and is used for observing the focus plate 7 with the eyes of the photographer.
[0029]
The main mirror 2, the focus plate 7, the pentaprism 8 and the eyepiece 11 constitute a finder optical system.
[0030]
Reference numeral 21 denotes a high-brightness LED that can be visually recognized even in a bright subject, and the emission center wavelength is red of 680 nanometers.
[0031]
Reference numeral 22 denotes an LCD (hereinafter referred to as SI-LCD) in which the positions of the nine focus detection areas are patterned, and only the pattern corresponding to the position where the focus detection area is selected among these SI-LCDs. Becomes a transmission state. The light emitted from the superimposing LED 21 (hereinafter referred to as SI-LED) behind the SI-LCD 22 passes only the transmission pattern of the SI-LCD 22 and passes through the light projecting lens 23 and the dichroic mirror 24. Through the eyepiece 11 and reach the photographer's eyeball. As a result, the photographer can view the focus detection area display pattern on the viewfinder screen. That is, as can be seen from the viewfinder field diagram shown in FIG. 3, at least one of the patterns 70 to 78 corresponding to the focus detection areas F0 to F8 shines within the viewfinder field, and the selected focus detection area is superimposed. can do.
[0032]
  Here, the dichroic mirror 24 has a characteristic of reflecting light having a wavelength of 680 nanometers or more, and the SI-LED21Can be efficiently guided to the eyes of the observer, and the light from the photographing lens can be observed by the photographer as a viewfinder field image with almost no light loss.
[0033]
Reference numeral 25 denotes an in-finder LCD (hereinafter referred to as F-LCD) for displaying photographing information outside the photographing screen within the viewfinder field, and is illuminated by an illumination LED (hereinafter referred to as F-LED) 26. The light transmitted through the F-LCD 25 is guided out of the photographing screen by the triangular prism 27 as shown in FIG. As a result, the photographer looking through the viewfinder can know various pieces of shooting information. In addition, 28 is a shutter speed display, 29 is an aperture value display segment, and 30 is a focus mark indicating the focus state of the taking lens 1.
[0034]
In FIG. 1, 31 is a diaphragm provided in the photographing lens 1, 32 is a diaphragm driving device including a diaphragm driving circuit 111, which will be described later, 33 is a lens driving motor, and 34 is a lens driving member composed of a driving gear and the like. is there.
[0035]
A photocoupler 35 detects the rotation of the pulse plate 36 interlocked with the lens driving member 34 and transmits this information to the lens focus adjustment circuit 110. The focus adjustment circuit 110 drives the lens driving motor 33 by a predetermined amount based on this information and the lens driving amount information from the camera side, and moves the photographing lens 1 to the in-focus position.
[0036]
Reference numeral 37 denotes a mount contact serving as an interface between the camera and the lens.
[0037]
  FIG. 2 shows a configuration of an electric circuit built in the single-lens reflex camera. A central processing unit (hereinafter referred to as a CPU) 100 of a microcomputer incorporated in the camera body includes a photometry circuit 102, an automatic focus detection circuit 103, a signal input circuit 104, an LCD drive circuit 105, an LED drive circuit 106, and shutter control. A circuit 108 and a motor control circuit 109 are connected. In addition, the focus adjustment circuit 110 and the aperture drive arranged in the photographing lenscircuit111 transmits a signal via the mount contact 37 shown in FIG.
[0038]
The EEPROM 100a attached to the CPU 100 has a storage function for storing various adjustment data.
[0039]
The photometric circuit 102 amplifies the luminance signals of the 19 small area sensors SPC-0 to SPC-18 sent from the photometric sensor 10, then performs logarithmic compression, A / D conversion, and CPU 100 as luminance information of each sensor. To send to.
[0040]
The line sensor 6f is a CCD line sensor constituted by nine sets of line sensors CCD-0 to CCD-8 corresponding to nine focus detection areas 70 to 78 in the finder screen.
[0041]
The automatic focus detection circuit 103 performs A / D conversion on the voltage obtained from these line sensors 6 f and sends it to the CPU 100.
[0042]
SW-1 (12) is a photometric switch that is turned on by the first stroke operation (half-press operation) of the release button and starts photometry and AF operations. SW-2 (13) is a release switch that is turned on by a second stroke operation (full pressing operation) of the release button. SW-DIAL1 and SW-DIAL2 (15) are dial switches provided in an electronic dial (not shown). Signals from these switches are input to an up / down counter of the signal input circuit 104, and the signal input circuit 104 is electronic. Count the number of clicks on the dial.
[0043]
Signals from these switches are input to the signal input circuit 104 and transmitted to the CPU 100 via a data bus.
[0044]
Reference numeral 105 denotes an LCD driving circuit for driving the liquid crystal display element LCD, and displays an aperture value, a shutter time, a set photographing mode, and other external monitor LCDs (not shown), an F-LCD 25, and the like in accordance with signals from the CPU 100. These are simultaneously controlled so as to be displayed on the SI-LCD 22 for superimposing.
[0045]
The LED drive circuit 106 controls lighting and blinking of the F-LED 26 and the SI-LED 21.
[0046]
The shutter control circuit 108 controls the magnet MG-1 that travels the front curtain and the magnet MG-2 that travels the rear curtain when energized to expose the photosensitive member 5 to a predetermined amount of light.
[0047]
When the photosensitive member 5 is a film, the motor control circuit 109 controls a motor M1 that winds and rewinds the film and a motor M2 that charges the main mirror 2 and the shutter 4. The shutter control circuit 108 and the motor control circuit 109 operate a series of camera release sequences.
[0048]
Next, the operation of the entire camera of this embodiment will be described based on the flowchart of FIG. Here, a case where the shutter priority AE is set will be described.
[0049]
When the camera is set to a predetermined shooting mode from the inoperative state, the camera is turned on (step # 100), and the camera waits until the release button is pressed and the switch SW1 (12) is turned on (step # 101). ).
[0050]
When it is detected through the signal input circuit 104 that the release button is pressed and the switch SW1 is turned on, the CPU 100 performs mutual communication with the lens mounted on the camera, and the camera performs photometry and AF. Necessary lens information, for example, open FNO. And information such as the best focus position are transferred to the memory of the camera (step # 102).
[0051]
Next, the nine sets of line sensors CCD-0 to CCD-8 are started to accumulate the object field light, and defocus amounts (image shift amounts) DEF0 to DEF8 in each sensor corresponding to the current photographing screen. Is calculated (step # 103).
[0052]
Next, in order to perform the focus detection operation, it is confirmed whether the focus detection area selection switch 14 is 0FF or ON, that is, whether the focus detection area selection mode is the automatic mode or the manual mode (step # 104). .
[0053]
Here, when the automatic mode is set, a specific focus detection area is selected by the focus detection area automatic selection subroutine (step # 105) based on the defocus amounts DEF0 to DEF8 in the nine focus detection areas. To do. Although several methods are conceivable as an algorithm for automatically selecting a focus detection area, a near point priority algorithm in which a weight is assigned to a central focus detection area is effective in a multipoint AF camera.
[0054]
When the manual mode is set, the photographer can arbitrarily select one of the nine focus detection areas by operating the switch dial 15 (step # 106). Thus, one focus detection area is determined automatically or manually (step # 107).
[0055]
  Next, in the determined focus detection area, the automatic focus detection circuit 103 performs focus detection calculation, and the determined focus detection area is the focus detection operation.ofPossibleNaIt is determined whether or not it is an area (step # 108). Where focus detection operationButWhen it is impossible, the CPU 100 sends a signal to the LCD drive circuit 105 to send an F-LCD.25The in-focus mark 30 blinks to warn the photographer that the focus detection is NG, while the focus detection is possible and selected by a predetermined algorithm.Focus detectionIf the focus adjustment state of the area is not in focus, the CPU 100 sends a signal to the lens focus adjustment circuit 110 to drive the photographing lens 1 by a predetermined amount (step # 109). Then, after driving the lens, it is determined whether or not the taking lens 1 is in focus (step # 110).
[0056]
  PredeterminedFocus detectionWhen the photographing lens 1 is in focus in the area, the CPU 100 sends a signal to the LCD drive circuit 105 to light the focus mark 30 of the F-LCD 25 and sends a signal to the LED drive circuit 106 to focus. The SI-LED 21 corresponding to the focus detection area being turned on is turned on, and the segment corresponding to the focus detection area is illuminated to display the in-focus state.
[0057]
At the same time, the CPU 100 transmits a signal to the photometry circuit 102 to perform photometry (step # 111). At this time, the photometry calculation is performed by weighting the photometry area corresponding to the focused focus detection area. Details of the photometry calculation will be described later. In the present embodiment, the photometric calculation result is displayed as a photographing lens aperture value (for example, F5.6) 29 using a segment and a decimal point.
[0058]
Next, whether or not the photographer accepts the focus state and the photometric value in the determined focus detection area is determined by turning ON / OFF SW1 (step # 112). Further, it is determined whether or not the release button is pressed and the switch SW2 is turned on. If the switch SW2 is turned off, the state of the switch SW1 is confirmed again (step # 113). On the other hand, when the switch SW2 is in the ON state, the CPU 100 transmits signals to the shutter control circuit 108, the motor control circuit 109, and the aperture driving circuit 111, respectively. The motor control circuit 109 energizes the motor M <b> 2 to raise the main mirror 2 and narrow the aperture 31. Thereafter, the shutter control circuit 108 energizes the magnet MG1 to open the front curtain of the shutter 4. The aperture value of the aperture 31 and the shutter speed of the shutter 4 are determined from the exposure value detected by the photometric circuit 102 and the sensitivity of the film 5.
[0059]
Then, after a predetermined shutter time (1/125 seconds) has elapsed, the magnet MG2 is energized, and the rear curtain of the shutter 4 is closed. When the exposure to the film 5 is completed, the motor M2 is energized again to perform mirror down and shutter charging, and the motor M1 is energized to feed the film frame by frame and complete a series of shutter release sequence operations. (Step # 114).
[0060]
Thereafter, the camera waits until the switch SW1 is turned on again (step # 101 return).
[0061]
Next, the photometric calculation performed in step # 111 will be described using the flowchart of FIG.
[0062]
In order to execute the photometric calculation, the CPU 100 first takes in the outputs (subject luminance raw signals) of the 19 divided sensors sent from the photometric circuit of the photometric sensor 10 and performs AD conversion of the output (step) # 200).
[0063]
Next, the open FNO. Which is the lens information of the photographing lens 1 obtained by the lens communication in step # 102. The AD-converted divided sensor output is corrected using data such as the amount of decrease in peripheral light amount and the like, and converted into a correct luminance signal of the photographic subject. Hereinafter, the corrected luminance signals of these small regions S0 to S18 are set to e0 to e18 (step # 201).
[0064]
At this time, the focus detection region in which the focus detection operation is to be performed in step # 107 described above is determined as one of F0 to F8. Therefore, in order to determine the photometric calculation to be performed according to the determined focus detection area, whether the determined focus detection area is substantially at the center of gravity of the photometric small area including the focus detection area, (Step # 202). Specifically, when the determined focus detection area is F1, F3, F5, or F7 on the boundary between the photometric small areas, the process proceeds to step # 203.
[0065]
In Step # 203, the luminance signals of a plurality of photometric small areas divided by the boundary (forming the boundary) are compared, and the photometric small area having the minimum luminance signal is determined as the main photometric area.
[0066]
  Here, a case where the focus detection area F1 is determined in step # 107 will be described as an example. In this case, the small photometric areas S1 and S3 are divided by the boundary where the focus detection area F1 exists, and the luminance signals e1 and e3 are compared in magnitude. As a result, if e1 <e3, the photometric small areaS1Is determined as the main photometry area, and if e1> e3, the photometry small areaS3Is determined as the main metering area.
[0067]
On the other hand, in step # 202, if the determined focus detection area is F0, F2, F4, F6, or F8, which is located at substantially the center of gravity of the small photometry area, the process proceeds to step # 204. In step # 204, the small photometric area having the determined focus detection area at the substantially center of gravity is automatically determined as the main photometric area. For example, when the focus detection area F2 is determined in step # 107, the small photometric area S1 is determined as the main photometric area.
[0068]
Next, the following method is used for weighted photometry calculation with the largest weight applied to the small photometry area (main photometry area) determined in step # 203 or step # 204. The photometric calculation described here can be classified into five arithmetic expressions as a result of the fact that one of the five photometric small areas S0 to S4 is determined in step # 203 or step # 204.
[0069]
Here, according to the above example, a detailed description will be given assuming that the photometric small area S1 is determined as the main photometric area, and the final photometry is performed when the other photometric small areas S0, S2, S3, and S4 are determined. Only the arithmetic expression is shown.
[0070]
  Step # 203 or step # 204When the photometric small area S1 is determined, the CPU 100 divides the photometric small areas S0 to S18 into three groups A, B, and C concentrically with the photometric small area S1 as the center. First, only the photometric small area S1 is set to the A group, the photometric small areas S0, S3, S7, S8 corresponding to the area surrounding the photometric small area S1 are set to the B group, and the other photometric small areas S2, S4, S5, S6, S9 to S18 is set to group C (step # 205).
[0071]
Next, in consideration of the area of each small photometric area, the above A, B, C groups are weighted. The approximate area ratio of each photometric subregion is
(S0, S1, S2, S3, S4): (S5, S6, S7, S8, S9, S10): (S11, S12, S13, S14): (S15, S16, S17, S18) = 3: 2: 4:12
So
The average luminance of each group: EA1, EB1, and EC1 can be obtained as follows.
[0072]
EA1 = e1 (1)
EB1 = (3 (e0 + e3) +2 (e7 + e8)) / 10 (2)
EC1 = (3 (e2 + e4) +2 (e5 + e6 + e9 + e10) +4 (e11 + e12 + e13 + e14) +12 (e15 + e16 + e17 + e18)) / 78 (3)
Here, e0 to e18 are output values of luminance signals corresponding to the photometric small areas S0 to S18, respectively.
[0073]
Since the main subject position is considered to be in the A group, by setting the weighting condition A: B: C = 3: 2: 1 with emphasis on A, photometry with emphasis on the main subject can be performed.
[0074]
From the above, the photometric value (exposure value): E with emphasis on the main subject can be obtained by the following equation.
[0075]
  E = (3EA1+ 2EB1+ EC1) / 6 (Unit: BV) ...4
  More than1~4Step #203 or step # 204Even if any of the small photometric areas S0 to S4 is selected as the main photometric area, the same is used. The equation for each case is shown below. In either case,4The expression is common (step # 206).
[0076]
When the main metering area is S0,
EA0 = e0
EB0 = (3 (e1 + e2) +2 (e5 + e6)) / 10
EC0 = (3 (e3 + e4) +2 (e7 + e8 + e9 + e10) +4 (e11 + e12 + e13 + e14) +12 (e15 + e16 + e17 + e18)) / 78
It is.
[0077]
When the main metering area is S2,
EA2 = e2
EB2 = (3 (e0 + e4) +2 (e9 + e10)) / 10
EC2 = (3 (e1 + e3) +2 (e5 + e6 + e7 + e8) +4 (e11 + e12 + e13 + e14) +12 (e15 + e16 + e17 + e18)) / 78
It is.
[0078]
When the main metering area is S3,
EA3 = e3
EB3 = (3e1 + 4 (e11 + e12)) / 11
EC3 = (3 (e0 + e2 + e4) +2 (e5 + e6 + e7 + e8 + e9 + e10) +4 (e13 + e14) +12 (e15 + e16 + e17 + e18)) / 77
It is.
[0079]
When the main metering area is S4,
EA4 = e4
EB4 = (3e2 + 4 (e13 + e14)) / 11
EC4 = (3 (e0 + e1 + e3) +2 (e5 + e6 + e7 + e8 + e9 + e10) +4 (e11 + e12) +12 (e15 + e16 + e17 + e18)) / 77
It is.
[0080]
In step # 203, if the brightness of the photometric subregions S1 and S3 divided by the boundary is exactly the same, that is, the result that e1 = e3 is obtained, it is determined that the main photographing subject is relatively large and step # In 205, the photometric small areas S1 and S3 are both set as main photometric areas. In this case, EA, EB, and EC are obtained by the following equations, and the photometric value is finally obtained by the equation (4).
[0081]
EA13 = (e1 + e3) / 2
EB13 = (3e0 + 2 (e7 + e8) +4 (e11 + e12)) / 15
EC13 = (3 (e2 + e4) +2 (e5 + e7 + e8 + e10) +4 (e13 + e14) +12 (e15 + e16 + e17 + e18)) / 70
FIG. 6 shows an example of a shooting scene of a camera in which the photometric calculation is effective. In the scene shown in this figure, first, a focus detection area F1 corresponding to the center position of the face of the main subject is determined by automatic selection of the focus detection area of the camera, and the focus adjustment operation of the photographing lens 1 is performed with respect to this focus detection area F1. Done.
[0082]
At this time, the camera performs the photometric calculation described above. That is, the luminance signals e1 and e3 of the small photometric areas S1 and S3 in which the focus detection area F1 is positioned on the division boundary are compared.
[0083]
As is clear from FIG. 6, the photometric small area S3 detects bright luminance of the background at the top as the luminance of the photometric small area, and the photometric small area S1 mainly detects the luminance of the face of the main subject. is doing. For this reason, in such a backlit photographic scene, in most cases, the luminance of the main subject is a dark value, and as a result, the photometric small area S1 in which the dark luminance is detected is determined as the main photometric area. Therefore, by executing the above photometric calculation, it is possible to obtain a photometric calculation value in which the luminance of the face of the main subject is weighted.
[0084]
On the other hand, in a photographic scene with a relatively uniform luminance distribution, a small photometric area that is different from the small photometric area in which the focus detection area corresponding to the main subject position is located on the division boundary is used as the main photometric area. Even if the decision is made and the weighting calculation is performed, it is clear that the calculation is almost the same as the calculation focusing on the main subject.
[0085]
Therefore, when shooting a shooting scene that does not have a uniform luminance distribution, as described above, when the determined focus detection area is on the dividing boundary of the plurality of photometric subareas, the luminance of the plurality of photometric subareas is set. In comparison, the smallest photometric area with the lowest luminance is determined as the main photometric area, and weighted photometric calculation with the maximum weight applied to the luminance of this main photometric area is used to properly shoot the main subject. It is very effective to do.
[0086]
However, in certain types of shooting scenes, it may be inappropriate to perform the photometric calculation with the maximum weighting applied to the luminance signal of the small photometric area having the minimum luminance.
[0087]
For example, when the main subject is wearing a black hat or wearing black clothes, if the low luminance signal is emphasized, the overall exposure may be overexposed. For this reason, in such a case, a luminance range higher than a luminance value that is lower by a predetermined level (for example, two levels) than the average value of a plurality of small photometric areas in which the determined focus detection area is positioned on the boundary. Among them, a small photometric area that generates a luminance signal is considered as a candidate for the lowest luminance, but a condition is added that a small photometric area that generates a low luminance signal exceeding a predetermined level is excluded from the candidates. As a result, the remarkably low luminance in the vicinity of the main subject is not weighted, and inappropriate exposure in the scene can be avoided.
[0088]
(Second Embodiment)
FIG. 7 shows a viewfinder view of a single-lens reflex camera according to the second embodiment of the present invention. In the present embodiment, as shown in FIG. 7, the focus detection area is newly provided with 10 areas (F9 to F18) in the outer circumferential direction in addition to the 9 areas (F0 to F8) of the first embodiment. Focus detection in a total of 19 areas is possible. Since the camera components and the operation sequence of the entire camera are the same as those of the camera of the first embodiment, only the difference in photometric calculation will be described here.
[0089]
In the camera of this embodiment, the operability in the focus adjustment of the photographer is improved by expanding the focus detection area to 19 areas. However, due to the configuration of the camera, the photometric sensor is a 19-division type as in the first embodiment. This sensor is used. For this reason, the focus detection areas F9, F10, F14, and F15 are arranged on the boundaries of the four photometric small areas, and the focus detection areas that perform the focus detection operation are the focus detection areas F9, F10, F14, and F15. The problem is how to perform proper photometry on the main subject when it is confirmed.
[0090]
The photometric calculation method in this case will be described by taking as an example the case where the focus detection area F9 is determined as the focus detection area where the focus detection operation of the camera is to be performed.
[0091]
First, there are four small photometric areas S0, S1, S5, and S7 that have the focus detection area at the position of the center of gravity in the vicinity of the focus detection area F9 and can measure the main subject correctly. Therefore, the detected luminance (luminance signal) in these small photometric areas is set to e0, e1, e5, e7.
[0092]
At this time, as in the first embodiment, the photometric small area having the lowest luminance among the luminance signals e0, e1, e5, and e7 is determined as the photometric small area (main photometric area) corresponding to the main subject position. To do. Here, for example, when the luminance signal e5 is the lowest, photometry calculation with the largest weighting is performed on the small photometry area S5, and photometry is performed with emphasis on the main subject. The calculation formula for the weighted photometry calculation is the same as that described in the first embodiment.
[0093]
In each of the above embodiments, the case where the focus detection area is arranged on the boundary of a plurality of small photometric areas has been described. The present invention can also be applied to a case where it is located at a position close to the boundary.
[0094]
In addition, the present invention can be applied to various types of cameras such as a single-lens reflex camera, a lens shutter camera, and a video camera. Furthermore, optical devices other than cameras and other devices, and further, these cameras and optical devices, It is applicable also to the apparatus applied to another apparatus, or the element which comprises these.
[0095]
【The invention's effect】
As described above, according to the present invention, when the focus detection area selected by the focus detection area selection means is a focus detection area near the division boundary, detection of a plurality of photometric areas divided by the boundary is detected. Since the main photometry area is determined by comparing the luminance, the focus detection operation of the main subject is performed finder optically, especially when the main subject is located in any of the many focus detection areas. Even if the focus detection area to be performed is not located at almost the center of gravity of the small photometric area that encompasses this area or is located on the boundary, the main area is Optimal metering can be performed with the subject at the center and taking the entire object field into consideration.
[Brief description of the drawings]
FIG. 1 is a schematic view of a single-lens reflex camera according to a first embodiment of the present invention.
FIG. 2 is an electric circuit diagram of the camera.
FIG. 3 is a viewfinder view of the camera.
FIG. 4 is an operation flowchart of the camera.
FIG. 5 is a photometric calculation flowchart of the camera.
FIG. 6 is an example of a composition taken by the camera.
FIG. 7 is a viewfinder view of the camera according to the second embodiment of the present invention.
[Explanation of symbols]
1: Shooting lens
6: Focus detection device
6f: Image sensor
7: Focus plate
10: Photometric sensor
11: Eyepiece
100: CPU
102: Photometric circuit
103: Focus detection circuit
S0 to S18: Photometric small area
F0 to F8, F9 to F18: Focus detection area

Claims (5)

A photometric sensor that measures luminance in a plurality of photometric areas using a part of the luminous flux from the subject;
A focus detection sensor capable of performing focus detection in a plurality of focus detection areas using a light beam different from a light beam directed to the photometric sensor among light beams from the subject; and
A focus detection area selecting means for selecting a focus detection area for performing a focus detection operation from the plurality of focus detection areas;
Have a control means for determining a main metering area on the basis of the focus detection area selected by the focus detection area selecting means,
The plurality of focus detection areas include a focus detection area corresponding to each of the photometry areas on a one-to-one basis and a focus detection area located on a boundary between the plurality of adjacent photometry areas in the shooting screen. ,
When the focus detection area selected by the focus detection area selection means has a one-to-one correspondence with the photometry area, the control means sets the corresponding photometry area as a main photometry area, and the focus detection area selection means A camera characterized in that, when a selected focus detection area is located on the boundary, a photometry area having the lowest luminance among a plurality of photometry areas forming the boundary is set as a main photometry area . When the focus detection area selected by the focus detection area selection means is located on the boundary, the control means is the highest in a brightness range higher than a predetermined brightness value among a plurality of adjacent photometry areas. 2. The camera according to claim 1, wherein a photometric area having a low detection luminance is determined as a main photometric area . Said control means, said main metering area on the basis of the detection brightness of camera according to claim 1 or 2, characterized in that the photometric calculation for exposure value determination. The camera according to claim 3 , wherein the control unit performs weighted photometry calculation by giving the maximum weight to the detected luminance of the main photometric area. 5. The camera according to claim 4 , wherein the control unit performs photometric calculation using only the detected luminance within a predetermined luminance range among the detected luminances of the plurality of photometric areas.

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