JP3098048B2 - Camera system for flash photography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera for flash photography.
About the system .

[0002]

2. Description of the Related Art Conventionally, there have been proposed a large number of flash light control cameras that perform flash light emission toward a subject, measure the reflected light of the subject, and control the amount of light emission. Most of these cameras use a single photometric sensor to control the screen by center-weighted photometry. Therefore, if the main subject is located at the center of the screen and has an appropriate size on the screen, proper exposure can be obtained.However, if the main subject is not located at the center of the screen or is very small on the screen, the photometric sensor will be affected by the background. And a proper exposure could not be obtained.

Japanese Patent Application Laid-Open No. Sho 60-10827 proposes a multi-flash camera that divides the screen into a plurality of sections and controls the amount of light emission based on information from a plurality of photometric sensors.

[0004] This proposal increases the probability of obtaining an appropriate exposure regardless of the position and size of the main subject. However, it is necessary to externally set which part of the screen should be emphasized for photometry. And the operation is troublesome.

[0005] The present applicant has in flash emission light control camera system developed prior to the present application, the photometry means a plurality of areas and the distance measuring means of the area thereof corresponding provided, have group Dzu the subject focus information of each area with a plurality A multi-flash camera system that evaluates the photometric information of the area and controls the amount of light emission was proposed.

With this proposal, it has become possible for a camera to automatically determine the position and size of a main subject and obtain an appropriate exposure.

[0007] According to JP-A-60-108827, means for metering the subject of the natural light state is divided on the screen into a plurality of means for metering reflected light from the subject during flash emission provided, a plurality The state of the subject is determined based on the photometry value divided into two, and the photometry value at the time of flash light emission is evaluated to determine the light emission amount. According to this proposal, it is also possible to determine the position and size of the main subject and predict the state of the background to achieve proper exposure.

[0008]

However, measuring the reflected light from the subject for each area during the flash emission described above requires a plurality of sensors in the camera, which increases the cost of parts and increases the control cost. Also has the drawback of being complicated.

[0009] In JP 60-108827 discloses <br/> is disadvantage luminance difference of the main object and the background of the effect is limited, such as when a large, does not correspond to the various shooting conditions was there.

An object of the invention according to this application is to provide a camera system for the aforementioned not have the disadvantages, flash photographing that emits controlled to proper exposure even when any conditions can be obtained.

[0011]

According to a first aspect of the present invention, a photographing screen is provided.
Is divided into multiple areas, and each area is measured separately.
A photometric circuit and an object prior to flash photography by the photometric circuit;
Each photometric value in each area when the light is emitted to
Detects each photometric value in each area without the light emission
The light metering control means
Of the measured photometry value and the photometry value detected when the
Find the difference in the area, and flash based on the difference in each area
Characterized in that light emission amount control means for controlling the amount is provided.
This is a camera system for flash photography. No.
In the invention of the second aspect, the shooting screen is divided into a plurality of
A photometric circuit that separately measures the area, and a flash
Each time light is projected on the subject prior to shooting
Each photometric value in the area and each area without
Metering control means for detecting each metering value in the
The light metering value detected when the
The difference between each area and the known photometric value is calculated.
Calculates the subtraction value between the maximum value of the differences between
Calculating means for controlling the amount of flash light based on the calculated value
Flash photography characterized by providing light emission amount control means
Camera system.

[0012]

According to the first aspect of the present invention, light projection and non-light emission are performed for each area.
The difference between the photometric values at the time of light emission is obtained.
Is the difference between the maximum value of the differences for each region and the difference between the other regions.
By providing a calculation means for calculating a subtraction value from the
Can be evaluated on the screen of
When the subject is located only at a short distance on a part of the surface,
The difference between light emission and non-light emission in that area is greater than the difference in other areas.
growing. Therefore, the state of the screen is estimated according to this difference.
In such a case (light emission in that area and
The difference when no light is projected becomes larger than the difference in other areas. )
Areas other than that area are in a situation where no object exists.
Therefore, light is applied so that the area other than that area is properly exposed.
When the amount is controlled, the object at a short distance is
So that the amount of light is
Gives proper exposure to the subject if controlled
You can do it.

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

FIG. 2 is an electric control block diagram of a camera embodying the present invention.

Reference numeral 1 denotes a microcomputer which controls the movement of each part of the camera.

Reference numeral 2 denotes a lens control circuit for controlling a distance ring and an aperture of a photographic lens (not shown). The lens control circuit 2 performs serial communication via DBUS while receiving the LCOM signal from the microcomputer 1. The lens control circuit 2 controls a motor (not shown) based on this communication content,
Control the distance ring and aperture. Further, the microcomputer 1 receives focal length information of the lens, distance information, and other various correction information.

Reference numeral 3 denotes a liquid crystal display circuit which displays each camera's photographing information such as a shutter speed and an aperture control value. The liquid crystal display circuit 3 performs serial communication via DBUS while receiving the DPCOM signal from the microcomputer 1. The liquid crystal display circuit 3 performs liquid crystal display based on the communication contents.

Reference numeral 4 denotes a switch sense circuit, which is always supplied with power together with the liquid crystal display circuit 3, and is a switch sw1 linked to the first stroke of the release button of the camera, and other switches for determining an exposure mode (not shown). A switch for determining the AF mode can always be read. When the switch is switched, the switch sense circuit 4 sends a signal to a DC / DC converter (not shown),
Activate the C / DC converter. The DC / DC converter supplies power to the microcomputer 1 and other circuits. The switch sense circuit 4 performs serial communication via DBUS while receiving the SWCOM signal from the microcomputer 1. When the switch sense circuit 4 receives a DC / DC off command from the microcomputer 1, it turns off the output of the DC / DC converter. The microcomputer 1 receives each switch information.

Reference numeral 5 denotes a strobe light emission control circuit which controls light emission and light control of the strobe light, a circuit for storing electric charges for light emission, a xenon tube serving as a light emitting portion, a trigger circuit, and light emission stop. It consists of existing circuits such as a circuit, a film surface photometric circuit, and an integrating circuit.

The X contact is turned on by the front curtain running of the shutter unit. The X contact of the strobe light emission control circuit 5 is ON
To start the flash of the strobe.

Reference numeral 6 denotes a focus detection unit, which is a circuit for determining at which position the subject is focused by the photographing lens by the existing phase difference detection method. The microcomputer 1 drives the focus detection unit 6, determines the focus state of the subject, and drives the lens distance ring and determines the focus.

Numeral 7 denotes a photometric circuit which divides the screen into a plurality of areas A0 to A5 as shown in FIG.

A shutter control circuit 8 controls a shutter unit (not shown) in accordance with a control signal from the microcomputer 1.

Reference numeral 9 denotes a feeding circuit which controls a feeding motor (not shown) in accordance with a control signal from the microcomputer 1 to wind and rewind the film.

Reference numeral 10 denotes a lamp circuit, which turns on the lamp toward the subject by the LAMP signal of the microcomputer 1. This lamp is used for alleviating red-eye during flash photography, and is turned on for several seconds prior to the exposure operation.

The switch sw2 is linked to the second stroke of the release button of the camera.
If N, the microcomputer 1 starts an exposure operation.

Next, the operation of the microcomputer 1 will be described with reference to FIG.

As described above, when the switch is switched, D
The C / DC converter is activated, and the operation of the microcomputer 1 starts. At this time, each flag on the RAM is cleared to 0.

First, when the camera starts operating, the microcomputer 1 communicates with the switch sense circuit 4,
The various switches are read (S1).

If AFLOCK FLG is 1 in S2, the focus detection has already been completed and the AF is locked, so that S
Proceed to 15.

Next, the microcomputer 1 drives the focus detection unit 6, detects the focus of the object, and drives the lens distance ring to focus on the object by communicating with the lens control circuit 2 (S3).

If the AF mode is a one-shot AF mode in which AF is locked once in focus, AFL
OCK FLG is set to 1. When the mode is not the one-shot AF mode, AFLOCK FLG is set to 0 (S4-S
6).

The microcomputer 1 uses a photometric circuit 7 and a plurality of areas A0 to A as shown in FIG.
Photometry of the subject 5 is performed (S7).

Here, if LAMP FLG is 1 (S8), the process proceeds to S13 because the red-eye reduction lamp has already been turned on. If LAMP FLG is 0, the microcomputer 1 stores the photometric value of each of the areas A0 to A5 on the RAM (S9), turns on the LAMP signal to turn on the red-eye reduction lamp (S10), and causes the LAM.
PFLG is set to 1 (S11), and a ramp timer is started (S12).

[0042] In S13, the have group Dzu the photometric value of each area photometry in S7 to determine the proper exposure amount by a predetermined algorithm, the shutter speed and aperture to have set exposure mode based Dzu <br/> switch, etc. Determine values, etc.

Next, the shutter time, aperture, and other photographing conditions are displayed using the liquid crystal display circuit 3 (S1).
4).

If the switch sw1 is off (S15), the microcomputer 1 turns off the red-eye reduction lamp (S16), turns off the DC / DC converter (S24), and ends the operation. .

If the switch sw1 is ON in S15, the microcomputer 1 looks at the lamp timer (S17), and if the predetermined time has not elapsed, returns to S1 and repeats the above-described sequence. If the predetermined time has come, the switch sw2 is looked at (S18), and if it is OFF, the process returns to S1. This is because it takes time for the human pupil to close in response to light, so that the effect of red-eye reduction is sufficient to release and perform flash photography.

If the switch sw2 is ON in S18,
The process proceeds to the release sequence after S19.

When the microcomputer 1 enters the release sequence, the microcomputer 1 uses the photometry circuit 7 again with the red-eye reduction lamp turned on, and performs photometry of the subjects in the plurality of areas A0 to A5 shown in FIG. 3 (S19). Therefore, each area A0
The difference σB _x between the photometric value of A5 to A5 and the photometric value of each of the areas A0 to A5 stored in S9 is calculated, and the dimming correction amount σL is calculated by an algorithm described later. And IS
The value obtained by adding σL to the light control value L that sets the flash light emission amount based on the O sensitivity and the like to the appropriate exposure amount is sent to the flash light emission control circuit 5 through communication as light control information (S20).

Then, the lamp for red-eye reduction is turned off by turning off the LAMP signal (S21), the aperture control is performed by communicating with the lens control circuit 2, and the shutter control is performed by driving the shutter control circuit 8. (S22). At this time, the flash emission control circuit 5
When the X contact is turned on during the front curtain operation of the shutter unit, the flash of the strobe starts. Simultaneously metering and integration of film surface light starts and stops the light emission of the strobe with the proper amount of exposure have groups Dzu the dimming information.

When the exposure operation is completed, the microcomputer 1 drives the feeding circuit 9 to feed the film for one frame for the next photographing (S23) and turns off the DC / DC converter (S24). , End the operation.

Next, an algorithm for obtaining the dimming correction amount σL will be described in detail.

First, the largest one of σB _x , which is the difference between the photometric value of natural light in each area and the photometric value at the time of lamp irradiation, is found. The difference between the maxσB _x and each σB _x is obtained, and the value is multiplied by a coefficient κ _x for each area,
The evaluation value V is obtained by adding them together.

V = Σ (maxσB _x −σB _x ) κ _x κ _x is the area A0 of the photometric sensor of the red-eye reduction lamp.
It is a coefficient obtained from the irradiation light intensity corresponding to A5 and the sensitivity ratio of the film surface photometry circuit in each area of the photometry sensor. Therefore, the lamp is irradiated toward a uniform white wall perpendicular to the optical axis of the camera, σB _x at that time is obtained, and the sensitivity distribution of each area of the photometric sensor and the sensitivity of the film surface photometric circuit are obtained. By obtaining the distribution, κ _x can be obtained experimentally.

Then, as shown in Table 1, the value of the dimming correction amount σL is obtained from the value of the evaluation value V. That is, the higher the evaluation value, the larger the correction amount.

[0054]

[Table 1]

According to this algorithm, it is considered that an object closest to the camera exists in the area having the largest value of σB _x , so that this is set as a main object, and in order to make this main object proper exposure, Σ in other areas
The B _x compared to maxσB _x, factor of the value or give how much impact for the film surface photometry circuit κ
_The evaluation value V is calculated by adding the values obtained by multiplying _x .

Therefore, the smaller the σB _x of the area where the main subject does not exist, and the higher the sensitivity of the area where the main subject does not exist for the film surface photometric circuit, or the higher the illuminance of the lamp, the larger κ _x becomes. , The evaluation value V increases. When the evaluation value V increases, the light amount received by the film surface photometry circuit becomes smaller than the luminance of the main subject when the strobe light is emitted. It will be over. Therefore, the main subject can be brought to an appropriate exposure amount by correcting the light control amount in the under direction in accordance with the evaluation value V.

As a supplement, in order to obtain the maximum value of σB _x , since the illuminance differs for each area, it may not be possible to correctly recognize the area where the main subject exists. Therefore, the maximum value may be obtained by multiplying σB _x by a coefficient compared with the irradiation light intensity.

Next, another algorithm for obtaining the dimming correction amount σL will be described.

First, the largest one of σB _x , which is the difference between the photometric value of natural light in each area and the photometric value at the time of lamp irradiation, is found. Then, a difference between maxσB _x and each σB _x is obtained, and it is determined whether the value exceeds a predetermined value. When the number of areas exceeding the predetermined value is d,
The value of the dimming correction amount σL is obtained from the value of d. As shown in Table 2, the larger the value of d, the larger the correction amount.

[0060]

[Table 2]

According to this algorithm, the larger the area without the main subject, the larger the value of d, and the smaller the amount of light received by the film surface photometric circuit with respect to the brightness of the main subject when the strobe light is emitted. If the light intensity L is not corrected, the main subject will be overexposed. Therefore, the main subject can be brought to an appropriate exposure amount by correcting the light control amount in the under direction in accordance with the evaluation value V. As a supplement, the coefficient j _x obtained from the sensitivity ratio of the film surface photometry circuit in each area of the photometry sensor, the area on the screen of each area, and the like is not used as the value of d instead of the number of simple areas, and (maxσB _x
If −σB _x ) is a value obtained by adding only the areas exceeding the predetermined value, the main subject can be more reliably brought to the proper exposure amount regardless of the area where the main subject exists.

In this embodiment, the subject is irradiated by the red-eye alleviating lamp before the exposure operation. However, the present invention is not limited to the red-eye alleviating lamp, but may be an LED or a strobe that emits light in advance. The same effect can be obtained.

[0063]

As described above, according to the present invention,
Always proper exposure of flash photography is Ru done.

[Brief description of the drawings]

[1] The control operation of the camera system embodying the present invention
The flowchart shown .

FIG. 2 is a block diagram illustrating a configuration of a control system of the camera system embodying the present invention.

FIG. 3 is a diagram showing an example of a photometric area in the photometric circuit of FIG . 2 ;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Microcomputer 2 ... Lens control circuit 3 ... Liquid crystal display circuit 4 ... Switch sense circuit 5 ... Strobe light emission control circuit 6 ... Focus detection unit 7 ... Photometry circuit 8 ... Shutter control 9 ... Feeding circuit 10 ... Lamp circuit

Claims (2)

(57) [Claims] 1. A photographing screen is divided into a plurality of areas,
A photometric circuit for separately measuring the split areas, and a flash
When projecting light to the subject prior to light shooting
Each photometric value in each area and each photometer without
A metering control means for detecting each metering value in the area, and
When a light metering value and light emission
The difference in each area from the detected photometric value is obtained, and
Light emission amount control means for controlling the amount of flash light emission based on the difference between
Camera system for flash photography characterized by the provision
M 2. A photometric circuit for dividing a photographing screen into a plurality of areas and separately measuring the light of each of the divided areas, and when the light metering circuit projects light on a subject prior to flash photography. and each of the photometry value in each region of the photometry control means for detecting the respective photometry values of the respective regions in a status of not the light projection, the photometric value detected by the status of not projecting and projecting Calculating means for calculating a difference between the photometric value detected at the time of performing the calculation in each area and calculating a subtraction value between a maximum value of the difference in each area and a difference in other areas; A camera system for flash photographing, comprising a light emission amount control means for controlling a flash light emission amount based on the image.