JPH10170977A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the probability to accurately recognize the change in composition of a photograph, by inhibiting the operation of detecting the change in the composition, when photometric output is lower than a fixed value. SOLUTION: A lens control circuit 2 executes serial communications through a data bus DBUS, while receiving an LCOM signal from a microcomputer 1, to control a motor with the contents of the communication and then, a distance ring and a diaphragm. A photometry circuit 7 divides a photometry area into plural ones and executes TTL photometry for the luminance of an object in each area., to transmit the luminance to the microcomputer 1. When the output value of a photometric sensor is of low luminance, so that the influence of noise and a dark current is exerted, at the time of detecting the fact that a photographer changes the composition by using the luminance distribution of a field or not, from the output of the photometric sensor, the function of detecting the fact that the composition is changed or not is inhibited or a level for recognizing the detection of the change on the composition is varied according to the output of the photometry sensor. Thus, even if strobe photographing is executed, the fluctuation of an exposure value is prevented and exposure at a proper light quantity is possible.

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 function of detecting whether or not a composition has been changed from a photometric output at the time of focusing and a photometric output immediately before photographing using a luminance distribution in an object scene. It is about improvement.

[0002]

2. Description of the Related Art Conventionally, TTL light control in which a strobe light emitted from a strobe device and reflected by an object is measured through a lens and a film surface of a camera and the strobe emission is stopped when the measured light output reaches a predetermined value. The device has been put to practical use.

[0003] Further, a multi-division dimming, which divides a photographing screen into a plurality of parts and calculates a divided photometric value, has also been put to practical use.
For example, as shown in FIGS. 4 and 5, three focus detection areas (hereinafter, referred to as focus detection points) are provided. In the case of a camera having a dimming area divided into four, the focus detection point is located on the left. Sometimes, the left two dimming areas are weighted twice as much as the other two dimming areas, and when the focus detection point is at the center, the middle two dimming areas are weighted twice as much as the left and right two dimming areas. Further, when the focus detection point is on the right side, a camera has been put to practical use in which the two right dimming areas are weighted twice as much as the other two dimming areas.

Further, as disclosed in Japanese Patent Publication No. Hei 7-13718, a sensor output of a focus detection point is stored from the outputs of a plurality of photometric sensors, and a sensor having a smaller value than the photometric value immediately before photographing is used when the main subject exists. There has also been proposed a device that estimates a region and performs light control in that region.

Further, in a camera equipped with an automatic focusing device, the position where the photographer wants to focus often does not always coincide with the position of the distance measuring sensor in the screen. A camera equipped with a function that corrects the flash emission amount of the flash device after detecting that the composition has been changed (framing has been performed) after focusing and then changing the photometry area and the weight at the time of flash shooting. Suggested by people.

[0006]

However, in the method of detecting a composition change using the output of the photometric sensor, when the luminance of the subject is lower than the low luminance limit of the photometric sensor,
The output of the photometric sensor often fluctuates due to the influence of dark current or noise, and it is erroneously detected that the composition has been changed even though the composition (framing) has not been changed, and the exposure value deviates from the photographer's intention. There were many.

(Object of the Invention) The present invention has been made in view of the above circumstances, and has as its object to provide a camera capable of increasing the probability of correctly recognizing a composition change.

[0008]

In order to achieve the above-mentioned object, the present invention according to claim 1 comprises: a photometer for measuring the brightness of a subject; a photometer output during focusing and a photometer output immediately before photographing. A camera having composition change detection means for detecting whether or not a composition change has been made using a luminance distribution in the object scene, if the photometric output obtained by the photometric means is lower than a predetermined value, the composition A composition change detection control means for prohibiting a composition change detection operation by the change detection means,
When the brightness of the subject is low such that the photometric output is affected by noise or dark current, detection of whether or not the composition has been changed is not performed.

According to another aspect of the present invention, there is provided a photometric device for measuring the luminance of a subject, and a luminance in an object scene is determined based on a photometric output during focusing and a photometric output immediately before photographing. In a camera including a composition change detection unit that detects whether a composition change has been made using the distribution, the composition change is performed by the composition change detection unit according to the photometric output obtained by the photometric unit. Composition change detection control means for changing the level for detecting that the subject has low brightness, such as when the photometric output is affected by noise or dark current, is used to detect whether or not the composition has been changed. It's hard to get rid of it.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a diagram showing an example of a specific configuration of an electric control block of a camera according to a first embodiment of the present invention. First, the configuration of each unit will be described.

Reference numeral 1 denotes a microcomputer (hereinafter, referred to as a microcomputer), which controls the operation of each part of the camera as described below. Reference numeral 2 denotes a lens control circuit which controls a distance ring and an aperture of a photographic lens (not shown). This lens control circuit 2
While receiving the LCOM signal from the microcomputer 1, serial communication is performed via the data bus DBUS, and a motor (not shown) is controlled based on the communication content to control the distance ring and the aperture. Further, the microcomputer 1 receives focal length information of the lens, distance information, best focus correction information, and other various correction information.

Reference numeral 3 denotes a liquid crystal display circuit, which is a circuit for displaying camera shooting information such as a shutter speed and an aperture control value. The liquid crystal display circuit 3 is provided with a D
While receiving the PCOM signal, serial communication is performed via the data bus DBUS, and liquid crystal display is performed based on the communication content.

Reference numeral 4 denotes a switch sense circuit, which is always supplied with power together with the liquid crystal display circuit 3 and, in a normal camera, a switch SW1 which is linked to a first stroke for starting preparation for photographing a release button of the camera. And a switch SW2 linked to the second stroke for starting the exposure operation, a switch for determining an exposure mode (not shown), a switch for determining a mode of automatic focusing (AF) of the camera, and the like can always be read. When the switch is switched, the switch sense circuit 4 performs serial communication via the data bus DBUS, and
Communicates each switch information.

Reference numeral 5 denotes a strobe light emitting circuit which controls light emission and dimming of the strobe light, a circuit for storing electric charges for light emission, a xenon tube as a light emitting portion, a trigger circuit,
It consists of an existing circuit such as a circuit for stopping light emission, a circuit equipped with a photometric sensor (see FIG. 5) for measuring the reflected light on the film surface, and an integrating circuit. The X contact, which is turned on by the front curtain of the shutter unit, is turned on. , Start the strobe.

Reference numeral 6 denotes a focus detection unit, which is a microcomputer 1
When the sensor accumulation start signal is received from the sensor, accumulation of the sensor is started and accumulation is performed until the accumulation level of the sensor becomes constant. When the accumulation level becomes constant, the accumulation of the sensor is terminated, and the completion of the accumulation of the sensor is serially communicated to the microcomputer 1 via the data bus DBUS. Then, the microcomputer 1 performs a sensor signal reading communication, reads a signal stored in the sensor, and synchronizes with the sensor driving signal to A.
The D / A conversion is performed, and from the A / D converted image signal of the subject, the position at which the subject is focused by the photographing lens is detected by calculation using an existing phase difference detection method.

There are three focus detection points as shown in FIG. 4. At these points, the above accumulation control and the like are performed, and the focus state is detected. At the time of dimming, for example, if the left is selected as the focus detection point, the two dimming regions on the left are weighted twice as much as the other two dimming regions (FIG. 5).
(A), when the focus detection point is at the center, the center two light control areas are weighted twice as much as the left and right two light control areas (FIG. 5).
(B), and when the focus detection point is on the right, the two dimming areas on the right are weighted twice as much as the other two dimming areas (see FIG. 5 (c)). become.

Reference numeral 7 denotes a photometric circuit, which displays a plurality of photometric areas A0, A1, A2, B3, B4, and C as shown in FIG.
5, each area A0, A1, A2, B3, B4
TTL photometry of the luminance of the subject C5 is sent to the microcomputer 1. Reference numeral 8 denotes a shutter control circuit,
The control of the shutter unit (not shown) is performed in accordance with the control signal. Reference numeral 9 denotes a feeding circuit which controls a film feeding motor in accordance with a control signal from the microcomputer 1 to wind up and rewind the film.

Reference numeral 10 denotes a memory which stores information necessary for photographing, and also stores a flag FRAME_CHANGE for storing that a composition change has been detected, a photometric value, an adjustment value of an automatic focusing device, film sensitivity information, and the like. Is stored in Reference numeral 11 denotes a line-of-sight detection device, which includes an existing circuit such as an infrared diode light emitting circuit, a dichroic mirror, and a CCD, and selects a focus detection point by detecting the line of sight of the photographer.

FIG. 2 is a flowchart showing the operation of the microcomputer 1 shown in FIG. 1. Hereinafter, the operation of the entire camera will be described with reference to this flowchart.

When the microcomputer 1 starts operation, first, in step # 51, a switch SW1 for starting photographing preparation is set.
Is determined to be ON, and if not, the process remains at step # 51. Thereafter, the switch SW1 is set to O
If N, the process proceeds to step # 52, in which the photometry circuit 2 is operated to determine the exposure amount, the brightness of the subject is measured, and photometry is performed. Here, to distinguish it from the photometry immediately before the release, it is named as "stationary photometry A".

In the next step # 53, the focus detection unit 6 is operated to detect the focus state of the subject and move the photographing lens to the focal position, thereby moving the photographing lens to the in-focus position. Then, in the next step # 54, it is determined whether or not the subject is in focus. If not, the process returns to step # 53, and the same operation is repeated. Thereafter, when the camera is in focus, the process proceeds to step # 55, in which the photometric value measured in step # 52 is fixed and stored in the memory 10 of FIG.

In the next step # 56, it is determined whether or not the switch SW1 is ON.
When it is OFF, the shooting is stopped, so step #
Returning to step 51, when the switch SW1 is ON, the process proceeds to step # 57. Then, in this step # 57, "stationary light metering B" is performed, and the routine proceeds to step # 58.
The photometric result of this “steady-state photometry B” is stored in the RAM. In the next step # 58, it is determined whether or not the switch SW2 is ON. If the switch SW2 is not ON, the process proceeds to step # 59. On the other hand, if the switch SW2 is ON, Go to step # 60.

In step # 59, it is determined whether or not the switch SW1 is turned on. When the switch SW1 is turned on, the flow returns to step # 57.
Otherwise, it is determined that the photographing has been stopped, and the process returns to step # 51.

That is, in this routine, the switch SW
When the switch SW2 is OFF while 1 remains ON, it means that photometry is performed at regular intervals and the "steady photometry value B" is updated.

When the switch SW2 is ON,
As described above, the process proceeds to step # 60, where it is determined whether the value of “steady photometry B” is greater than “BV-5”.
If it is larger than "5", the process proceeds to step # 61, where "BV-
If the value is smaller than 5 ", the reliability of the output of the photometric sensor is reduced due to noise or dark current of the sensor, and the composition may be erroneously detected.
Proceed to.

Step # 61 is a subroutine "composition change detection". The contents of this subroutine will be described later. In the next step # 62, "steady photometry B"
Is determined to be greater than 0.6 times the value of "steady-state photometry A". If the value is greater, the process proceeds to step # 63, where it is determined that the composition has been changed, and the flag FRA in the memory 10 is determined.
ME_CANCE is set to 1 to change the dimming weighting pattern.

When the composition is changed, the weighting of each sensor is made uniform as shown in FIG. This is because it is impossible to know where the main subject exists in the screen due to the framing.

On the other hand, when the value of "steady-state photometry B" is smaller than 0.6 times the value of "steady-state photometry A", or as described above, the value of "steady-state photometry B" is smaller than "BV-5". If it is determined in # 60, the process proceeds from step # 63 to step # 64, assuming that the composition has not been changed, and the flag FRAME_CANGE in the memory 10 is set to 0 to keep the dimming weighting pattern unchanged.

In the next step # 65, a battery check is performed by applying a load to the battery to determine whether or not the battery has a capacity capable of photographing by the camera. In the next step # 66, the result of the battery check is determined. As a result,
If the battery capacity is not enough to enable shooting, step # 74
Then, a warning is displayed to inform the photographer that the battery has no capacity.

If the battery capacity is sufficient for photographing, the process proceeds to step # 67, where the main mirror (not shown) is raised, and in the next step # 68,
In order to perform the release operation, the aperture of the lens is reduced to the aperture value determined based on the photometric value in step # 52. Then, in the next step # 69, the shutter is controlled to perform the exposure operation and the shutter is opened for a predetermined time, and in the next step # 70, the strobe light emission control is performed by the strobe light emission circuit 5. Next step # 71
In, the shutter closing operation is performed, and the following step #
In step 72, the aperture stopped down in step # 68 is returned to the open position. Finally, in step # 73, the photographed film is sent to the next frame, and the process returns to step # 51.

Thus, a series of operations is completed.

FIG. 3 is a flowchart of a subroutine "composition change detection", and the algorithm at the time of composition change will be described below with reference to this flowchart.

In step # 101, the average value of the photometric values of "stationary photometry A" is obtained. If the average value is A _AV, the average value is expressed by the following equation.

In the next step # 102, the average value of the photometric values of "stationary photometric B" is obtained. Assuming that the average value is B _AV , the average value is represented by the following equation.

In step # 103, the difference between the average value of the "stationary light metering A" and the output of each sensor is calculated. The value at this time is called △ A (i) (i = 0 to 5). i = 0-5
Are A0, A1, A2, B3, B shown in FIG.
4, C5. In the next step # 104, the difference between the average value of the stationary light metering B and the output of each sensor is calculated. The value at this time is called △ B (i) (i = 0 to 5).
i = 0 to 5 represent A0, A1, A2, and
B3, B4, C5.

In the next step # 105, a luminance distribution function at the time of focusing is obtained. This function is This represents how much the photometric value of each sensor of the multi-segment photometric sensor differs from the average value of the output, that is, the luminance distribution of the object field at the time of focusing. In other words, this value increases as the contrast of the subject increases.

In step # 106, a luminance distribution change function is obtained. This function is It can be determined whether or not the difference from the average value has changed as compared with the time of focusing.

In step # 107, the values obtained in steps # 105 and # 106 are stored in a memory.
Return to the main routine.

(Second Embodiment) FIG. 8 is a flowchart showing a series of operations of a camera according to a second embodiment of the present invention. Note that the electrical configuration and the like of this camera are the same as those in the first embodiment, and a description thereof will be omitted here.

The operation of the whole camera will be described below with reference to the flowchart of FIG.

When the microcomputer 1 starts operation, first, in step # 151, a switch SW for starting photographing preparation is set.
It is determined whether or not 1 is ON, and if it is not ON, the process stays at step # 151. Then, the switch SW1
Is turned on, the process proceeds to step # 152, the photometric circuit 2 is operated to determine the exposure amount, and the luminance of the subject is measured, and photometry is performed. Here, to distinguish it from the photometry immediately before the release, it is named as "stationary photometry A".

In the next step # 153, the focus detection unit 6 is operated to detect the focus state of the subject and move the photographing lens to the focal position, thereby moving the photographing lens to the in-focus position. Then, the next step # 154
In, it is determined whether or not the subject is in focus. If not, the process returns to step # 153, and the same operation is repeated. After that, if it becomes in focus, step # 1
Proceeding to 55, here the photometric value measured in step # 152 is fixed and stored in the memory 10.

In the next step # 156, it is determined whether or not the switch SW1 is turned on. When the switch SW1 is turned off, the photographing is stopped and the process returns to step # 151. If it is ON, the process proceeds to step # 157. And this step # 15
In step 7, “Constant light photometry B” is performed and step # 15 is performed.
Proceed to 8. The photometric result of this “steady-state photometry B” is stored in the RAM. In the next step # 158, it is determined whether or not the switch SW2 is turned on. If the switch SW2 is not turned on, the process proceeds to step # 159.
When the switch SW2 is ON, the process proceeds to step # 160.

In step # 159, it is determined whether or not the switch SW1 is turned on. When the switch SW1 is turned on, the process returns to step # 157. Otherwise, it is considered that the photographing has been stopped. To step # 151.

That is, in this routine, the switch SW
When the switch SW2 is OFF while 1 remains ON, it means that photometry is performed at regular intervals and the "steady photometry value B" is updated.

When the switch SW2 is ON,
Proceeding to step # 160, a subroutine "composition change detection" is performed, but the contents of this subroutine are the same as in the first embodiment (FIG. 3), and therefore, the description thereof is omitted.

In the next step # 161, the value of "steady photometric value B" is (0.6 * Y) of the value of "steady photometric value A".
It is determined whether it is larger than double, and if larger, step # 1
Proceed to 62, and if smaller, proceed to step # 163. Y is a correction coefficient that changes according to the luminance of the subject, and is represented by the following equation. Luminance of the object at this time although obtained in A _AV may be B _AV.

The above equation is illustrated in FIG. As can be seen from FIG. 9, the weighting is changed at low luminance. At low luminance, it is difficult to change the composition.

In step # 162, it is assumed that the composition has been changed, and the flag FRAME_
By setting CANGE to 1, the light control weighting pattern is changed.

When the composition is changed, the weighting of each sensor is made uniform as shown in FIG. This is because it is impossible to know where the main subject exists in the screen due to the framing.

On the other hand, in step # 163, assuming that the composition has not been changed, the flag FRAME_CANGE in the memory 10 is set to 0, and the dimming weighting pattern is not changed.

In the next step # 164, a load is applied to the battery to check whether or not the battery has a capacity that allows the camera to take a picture.
In, the result of the battery check is determined. As a result, if the battery capacity is not large enough to allow shooting, step #
Proceeding to 173, a warning is displayed to inform the photographer that the battery has no capacity.

If the battery capacity is sufficient for photographing, the process proceeds to step # 166, where the main mirror (not shown) is raised, and in the next step # 167, the above-mentioned steps are performed to perform the release operation. The aperture of the lens is narrowed down to the aperture value determined based on the photometric value in # 152. Then, in the next step # 168, the shutter is controlled to open the shutter for a predetermined time in order to perform the exposure operation, and in the next step # 169, the strobe light emission control is performed by the strobe light emission circuit 5. In the next step # 170, a shutter closing operation is performed.
In the following step # 171, the above-mentioned step # 167
Return the aperture stopped down to the open position, and finally step #
At 172, the photographed film is sent to the next frame, and the process returns to step # 151.

Thus, a series of operations is completed.

According to each of the above embodiments, in a camera for detecting whether or not the photographer has changed the composition from the output of the photometric sensor by using the luminance distribution of the object scene, the output value of the photometric sensor may be noise or dark current. When the brightness is low, the function for detecting whether or not the composition has been changed is prohibited (steps # 60 to # 64 in FIG. 2), or the level for recognizing the composition change detection according to the output of the photometric sensor. (Step # 61 → # 163 in FIG. 8), the exposure value does not fluctuate even when flash photography is performed, and exposure can be performed with an appropriate light amount.

(Correspondence between the Invention and the Embodiment) In each of the above embodiments, the photometric circuit 7 corresponds to the photometric means of the present invention, and the part of the microcomputer 1 for executing the operation of FIG. This corresponds to the detecting means, and corresponds to steps # 60 → # 64 in FIG.
The portion that executes the operation of 61 → # 163 corresponds to the composition change detection control means of the present invention.

The correspondence between the components of the embodiment and the components of the present invention has been described above. However, the present invention is not limited to the configuration of the embodiment, and the functions and features described in the claims are not limited.
Needless to say, any configuration may be used as long as the functions of the embodiment can be achieved.

(Modification) In the above embodiment, a camera having a plurality of focus detection points is taken as an example. However, a camera having a plurality of distance measurement points (regions for measuring the distance to the subject) may be used. Applicable.

Although the present invention has been described with respect to an example in which the present invention is applied to a single-lens reflex camera, the present invention is also applicable to cameras such as a lens shutter camera and an electronic still camera. Further, the present invention can be applied to other optical devices.

[0061]

As described above, according to the present invention,
If the photometric output is lower than the predetermined value, the composition change detection operation is prohibited, or the level for detecting that the composition has been changed is changed according to the obtained photometric output, so that the photometric output is When the brightness of the subject is low, such as when subject is affected by noise or dark current, it is difficult to detect whether the composition has been changed or not. It is possible to provide a camera capable of performing the following.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a single-lens reflex camera according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a series of operations of the camera of FIG.

FIG. 3 is a flowchart showing details of an operation of “composition change detection” executed in step # 61 of FIG. 2;

FIG. 4 is a view showing focus detection points provided in the camera of FIG. 1;

FIG. 5 is a diagram illustrating a relationship between a divided area of a light control sensor provided in the camera of FIG. 1 and a focus detection point to be selected;

FIG. 6 is a diagram illustrating a light control area when a composition change is performed in the camera of FIG. 1;

FIG. 7 is a diagram illustrating a photometry area of the camera in FIG. 1;

FIG. 8 is a flowchart showing a series of operations of the single-lens reflex camera according to the second embodiment of the present invention.

FIG. 9 is a diagram showing a correction coefficient that changes according to the luminance of a subject for detecting a composition change in the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microcomputer 5 Strobe light emission circuit 6 Focus detection unit 7 Photometry circuit 10 Memory

Claims (2)

[Claims] 1. A composition for detecting whether or not a composition has been changed using a luminance distribution in an object scene from a photometric unit for measuring the luminance of a subject, and a photometric output during focusing and a photometric output immediately before shooting. A camera provided with a change detection means, wherein a composition change detection control means is provided for prohibiting a composition change detection operation by the composition change detection means when a photometric output obtained by the photometry means is lower than a predetermined value. A camera characterized by the following. 2. A composition for detecting whether or not a composition has been changed using a luminance distribution in an object scene from a photometric unit for measuring the luminance of a subject, and a photometric output during focusing and a photometric output immediately before shooting. A composition change detection control unit that changes a level for detecting that a composition change has been made by the composition change detection unit in accordance with a photometric output obtained by the photometry unit. A camera characterized by being provided.