JPH08327886A - Camera with built-in stroboscope - Google Patents

Abstract

PURPOSE: To provide a camera with built-in stroboscope capable of photographing an object with an optimal exposure regardless of the position of a main subject by controlling stroboscopic light according to the position of main subject in the photographing visual field considering the variance of an irradiating light quantity due to the light distribution property of the stroboscope. CONSTITUTION: The degree of shortage of a stroboscopic light quantity, with which a range finding point of a main subject measured by a multi-point range finder 35 is irradiated, is found against the stroboscopic light quantity with which a range finding point on the center of photographing visual field is irradiated and the stroboscopic light is controlled so that the exposure by the stroboscopic light becomes an optimal exposure in accordance with a luminance in the photographing visual field measured by a photometric part 20 and a distance to the main subject measured by the multi-point range finder 35 i.e., so that the stroboscopic light with which the main subject is irradiated does not become under-exposure by compensating the exposure by the stroboscope for supplementing the shortage. Consequently, the appropriate exposure is obtained in the image plane independent of the position of main subject in the photographing visual field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera with a built-in strobe, and more particularly to a camera with a built-in strobe capable of taking an appropriate amount of exposure by operating an automatic exposure function and illuminating the strobe.

[0002]

2. Description of the Related Art Normally, when a person is photographed in the backlight, the face becomes dark, and when the sun is directly above the backlight, a shadow is formed on the face. A constant light emission method is known in which a strobe light is emitted even in the daytime in order to eliminate such a shadow of a subject, and strobe light is added to exposure by external light. When a negative color film is used, such a constant light emission method is preferred because it has a wide latitude against overexposure. As a camera with a built-in strobe that uses this type of constant light emission system, for example, that disclosed in Japanese Patent Laid-Open No. 56-14902 is known.

A photometric means for measuring the brightness of external light,
There is also proposed a camera with a built-in constant-flash strobe that has a distance measuring unit for measuring the subject distance and controls the exposure amount by strobe irradiation stepwise according to the external light brightness and the subject distance (Japanese Patent Application No. 6-255599). See the specification). On the other hand, distance measuring points are provided at a plurality of points (for example, 3 points)
The main subject is present among the three points (needs distance measurement) 1
A multi-point distance measuring AF (autofocus) in which a main subject is focused by a user selecting a point is also in practical use.

[0004]

However, the conventional strobe built-in camera has a non-uniform stroboscopic light distribution and generally has a light distribution characteristic that the light quantity in the peripheral portion of the visual field is reduced. When taking a picture of a composition in which the main subject is in the peripheral part of the field of view, there is a problem that the amount of exposure of the main subject by the strobe is insufficient.

In general, assuming that the amount of light emitted from a strobe is displayed as a guide number, it has a light distribution characteristic that satisfies the inverse square law of light. That is, all the light fluxes that reach the subject at the same distance are equivalent. However, there are various characteristics in the light distribution characteristics of the strobe light emission part, such as the shape of the discharge tube, the shape of the reflective umbrella, its reflectivity, and the diffusivity of the diffuser plate. There are few things that have become.
Further, the actual guide number is a measured value on the extension line of the center point of the strobe light emitting portion, and the irradiation distribution within the effective irradiation angle is non-uniform. Therefore, irradiation unevenness is given to the screen.

In such a non-uniform irradiation distribution, if a photograph of a composition in which the main subject is outside the center of the field of view is taken as described above, proper exposure cannot be obtained on the image plane, and good photography is taken. There is a problem that you can not. On the other hand, it is possible to increase the flash irradiation angle in order to approach the ideal light distribution characteristics to the extent that there is practically no problem, but it is difficult to increase the flash irradiation angle due to the design of the light emitting unit, so it is necessary Increasing the angle causes a problem that the irradiation light amount decreases and the guide number decreases.

The present invention has been made in view of such circumstances, and controls the strobe light in accordance with the position of the main subject in the photographing field of view in consideration of the variation of the light amount due to the light distribution characteristic of the strobe. Accordingly, it is an object of the present invention to provide a camera with a built-in flash that can shoot a subject with an optimum exposure amount regardless of the position (composition) of the main subject.

[0008]

In order to achieve the above object, the present invention provides a multi-point distance measuring means for measuring a distance to a distance measuring point where a main subject is present among a plurality of distance measuring points in a photographing visual field. And strobe light control means for controlling the strobe image plane exposure amount based on the distance measured by the multipoint distance measuring means and the position of the distance measuring point measured by the multipoint distance measuring means. It has a feature.

Further, in order to achieve the above object, the present invention provides:
A photometric means for measuring the brightness in the photographing field of view, a multi-point distance measuring means for measuring the distance to a distance measuring point where a main subject is present among a plurality of distance measuring points in the photographing field of view, and a predetermined shutter opening time. When the external light brightness at which the optimum exposure is obtained is set as the reference external light brightness and the exposure amount at this time is set as the standard exposure amount, the brightness outside the reference external light brightness is determined based on the brightness measured by the photometric means. An automatic exposure mechanism that opens and closes a shutter that also serves as a diaphragm blade so as to obtain the standard exposure amount when shooting under light, emits light in conjunction with the opening and closing operation of the shutter, and the brightness measured by the photometric means, And a strobe light control unit for controlling the strobe image plane exposure amount based on the distance measured by the multi-point distance measuring means and the position of the distance measuring point measured by the multi-point distance measuring means. .

[0010]

According to the present invention, there is a variation in the light amount due to the light distribution characteristic of the strobe between the light amount of the strobe light applied to the central part of the photographing field and the light amount of the strobe light irradiated to the peripheral part of the photographing field. Therefore, paying attention to the fact that the contribution of the strobe light on the image plane varies depending on the position of the main subject in the shooting field of view, and the position of the main subject in the shooting field of view is added to the parameter of the exposure amount control by the strobe. , The amount of exposure on the image surface is properly maintained.

According to the present invention, the distance is measured by the multi-point distance measuring means from a plurality of distance measuring points within the field of view of the photographing object at a distance measuring point at which the main subject exists. And with that distance,
On the basis of the positions of the distance measuring points measured by the multi-point distance measuring means, the strobe light control means controls the exposure amount of the image surface (strobe image surface exposure amount) by the strobe light irradiation. As a result, it is possible to correct variations in the amount of strobe irradiation light due to the strobe light distribution characteristic, and it is possible to obtain an appropriate amount of exposure on the image plane regardless of the position of the main subject within the shooting field of view.

Further, the strobe light control means measures the position where the main subject actually exists, that is, the distance measured by the multi-point distance measuring means with reference to the amount of strobe light irradiated to the distance measuring point at the center of the photographing field of view. The strobe image plane exposure amount is corrected on the basis of how much the strobe light amount irradiated to the position of the distance point is insufficient due to the strobe light distribution characteristic. As a result, it is possible to correct variations in the amount of strobe irradiation light due to the strobe light distribution characteristic, and it is possible to obtain an appropriate amount of exposure on the image plane regardless of the position of the main subject within the shooting field of view.

Further, an exposure amount replenishment value for replenishing the deficient amount for each of the distance measuring points is set in advance based on the light distribution characteristic of the strobe, so that the strobe can be used in correspondence with the position of the main subject. The exposure amount can be controlled instantly and easily.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a flash built-in camera according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the external appearance of an embodiment of a camera with a built-in strobe according to the present invention. The camera with a built-in flash shown in the figure has a shutter button 1 on the upper surface of a rectangular parallelepiped camera body 10.
1. A lens barrel 14 in which a selection dial 12 is arranged, and a taking lens 13 is incorporated in the center of the front surface of the camera body 10.
Is attached.

On the upper part of the front surface of the camera body 10, a light projector 15, a finder 16, a light receiver 17, and a strobe 18 are arranged from the left of the drawing. Among these, the light projector 15 includes a plurality of (three in this embodiment) light emitting elements (not shown), and the light receiver 17 includes a light receiving element corresponding to the light emitting element, and these light projectors 15 and 17 are known. It constitutes an active multi-point measuring device. The principle of active multi-point distance measurement is described in Japanese Patent Application Laid-Open No. 64-44411, which is not described in detail in this specification.

This multi-point distance measuring device obtains the distances to the object at a plurality of distance measuring points in the photographing field of view based on, for example, the principle of triangulation. As shown in FIG. Marks 19a, 19b, 19c indicating the positions of three AF (autofocus) sensors corresponding to the light emitting elements are set therein by superimposing LED display.

While looking through the viewfinder 16, the photographer selects the AF according to the position of the main subject in the photographing field of view.
One of the sensors, the AF sensor, is the selection dial 1
The AF function is activated at the distance measuring point corresponding to the AF sensor by selecting 2 and the distance can be measured in a wide area within the viewfinder field 16 '.
The mark corresponding to the AF sensor selected by the selection dial 12 is illuminated, for example, to indicate that the mark is being selected.

As described above, as the distance measuring point selecting means of the multi-point distance measuring device having the distance measuring point selecting function, in addition to manual input by the selection dial 12 shown in this embodiment, for example, line-of-sight input or automatic selection, etc. Can also be considered. Selection dial 12
For manual input using the
The distance measuring point is selected by switching the sensor. Every time the selection dial 12 is turned, the finder field of view 1
The distance measuring point can be confirmed by the blinking display in 6 '. On the other hand, the gaze input is performed by the photographer in the field of view 1
A sensor for detecting the line of sight (CC
D area sensor, etc.)
The F sensor is instantly selected. The automatic selection is to automatically select a distance measuring point that is likely to be a main subject from the distance measuring information of each of the three AF sensors. Select a point.

In this embodiment, the case where the selection dial 12 is used for manual selection will be described, but the distance measuring point may be selected by another method. Further, the AF sensor and the distance measuring points corresponding thereto are not limited to three points, and any number of points may be used. Further, the photographing field of view is not limited to three points and may be a plurality of AF areas (distance measuring areas). On the other hand, on the right side of the lens barrel 14 on the front surface of the camera body 10, a photometric unit 20 for measuring the brightness (outside light brightness) within the field of view is incorporated. The photometric unit 20 includes an incident window 20a formed on the surface of the camera body 10, a lens 20b arranged inside the incident window 20a, and a light receiving element having a light receiving surface near the image forming position of the lens 20b. 20c and.

The light receiving surface of the light receiving element 20c is the lens 2
Since the light receiving surface of the light receiving element 20c is not formed, a perfect image of the object is not formed on the light receiving surface of the light receiving element 20c, and the average outside light amount of the entire field of view including the main object is equal to the light receiving element. It is detected at 20c. Furthermore, camera body 1
A shutter 21 is provided on the optical axis of the taking lens 13 inside the camera 0 to give an exposure amount required for the film.

The strobe 18 automatically emits strobe light in accordance with the opening timing of the shutter 21, and in this embodiment, the strobe 18 light emission timing is slightly deviated from the opening timing of the shutter 21. By doing so, the exposure amount on the main subject surface is adjusted. This adjusting method will be described with reference to the time chart of FIG. The time chart shown in FIG. 3 shows how much exposure amount can be obtained when the strobe 18 emits light at a timing after the shutter 21 is started. As shown in FIG. 3A, when the strobe light is emitted at the timing when time t1 has elapsed since the shutter 21 was started (FIG. 3B), the opening area of the shutter 21 is still small and the light flux for exposing the film is also small. small. Therefore, the exposure amount is small (FIG. 3 (c)).

On the other hand, when the strobe light is emitted at the timing when the time t2 has elapsed since the shutter 21 was started (FIG. 3 (d)), the opening area of the shutter 21 is maximum, so that the film is opened. Is large. Therefore, the exposure amount is almost twice as much as the exposure amount at the time t1 (FIG. 3 (e)). By adjusting the light emission timing of the strobe 18 in this manner, the exposure amount by the strobe 18 can be freely adjusted without changing the light emission amount of the strobe 18 itself.

FIG. 4 shows an example of the light distribution characteristic of the strobe 18. The central figure (a) is a diagram in which the equal light intensity points of the strobe light that is irradiated to the surface perpendicular to the strobe light axis are connected.
The figure on the right side (b) shows that the amount of irradiation light decreases with increasing distance from the center point O of the optical axis in the up-down direction, and the figure on the lower side shows increasing distance from the center point of the optical axis in the left-right direction. It is shown that the amount of irradiation light decreases.

That is, normally, when a flash is emitted,
The amount of strobe light in the field of view for photographing is not uniform, the amount of irradiation light is large at the center of the optical axis, and the amount of light becomes smaller toward the periphery. Therefore, depending on where the main subject is in the photographing field of view, the amount of strobe light irradiated to the main subject varies. Conventional strobe light control is
The amount of strobe light is adjusted with reference to the center point O of the shooting field of view, and there is no problem if the main subject is near the center of the shooting field of view, but if the main subject is in the peripheral part of the shooting field of view, There is a problem that the amount of light is insufficient due to the strobe light distribution characteristic.

In the present embodiment, for a strobe having a strobe light distribution characteristic as shown in FIG. 4, in order to compensate for the shortage of the light amount with respect to the irradiation light amount of the central portion, the light amount is compensated for in correspondence with the position of the main subject in the field of view. A correction is given, and as the correction method, the supplementary value K is determined for each selected distance measuring point. For example, when the AF sensor corresponding to the mark 19a is selected as the position of the main subject in FIG. 2 and the distance D measured by the AF sensor is at a distance D, the strobe light amount I ′ radiated to the main subject is 1 compared to the strobe light intensity I0 emitted to the center
Assuming that it has a light distribution characteristic of being / 4 short (i.e., I '= 3 / 4I0), the flash exposure amount calculated for the case where the main subject is located in the center of the visual field is further reduced. It is determined that the shortage is compensated by multiplying the supplement value by 4/3 times.

In general, assuming that there are a plurality of distance measuring points (or distance measuring areas) within the field of view, the nth distance measuring point (or distance measuring area) among them is relative to the irradiation light amount at the center of the visual field. Then, based on the data of how much light quantity is insufficient, the exposure amount supplement value of the strobe light for compensating for the insufficient light quantity is set to the position (ranging point or area) of the main subject in the shooting field of view and It is desirable to set the subject distance as a parameter in advance.

The light distribution characteristic is previously recognized, and is converted into data by using the position and the distance within the photographing field of view as parameters, and which of the positions and distances of the main subject within the photographing field is represented. It is determined whether or not an appropriate exposure amount can be obtained by giving a supplementary amount of exposure amount.
It is stored in the PU 30 (see FIG. 5). Then, based on the distance measuring point (position of the main subject) corresponding to the AF sensor selected by the selection dial 12, the distance measured at the distance measuring point, and the brightness measured by the photometric unit 20, the photographing is performed. The strobe light emission timing is controlled to obtain the optimum exposure.

FIG. 5 is a block diagram showing a specific structure for controlling the light emission timing. As shown in the figure, the CPU 30 mainly performs the light emission timing control based on the control program 31a written in the ROM 31. To the CPU 30, a distance measuring point selection signal is given from the selection dial 12, and a half-push signal or a full-push signal is given from the shutter button 11. The CPU 30, which has received the distance measuring point selection signal from the selection dial 12 and the half-press signal from the shutter button 11, sends a signal for measuring the distance to the main subject to the multipoint distance measuring device 35.
And a signal for measuring the luminance within the field of view are given to the photometric unit 20.

When the distance measuring point corresponding to the position of the main subject is selected by the selection dial 12, the CPU 30 issues a control signal to the multi-point distance measuring device 35 and the photometry unit 20. The multi-point distance measuring device 35 receives the signal and performs distance measurement, while the photometry unit 20 performs light measurement. Then, each measurement result is given to the CPU 30. Based on these measurement results, the CPU 30 determines the replenishment value K necessary for strobe light emission, and also performs calculation for controlling strobe light emission (see steps 110 to 112 in FIG. 6).

Upon receiving the full-press signal from the shutter button 11, the CPU 30 provides the strobe 18 with a signal for flash firing and the shutter 21 with a signal for opening / closing the shutter. Next, the flow of processing of light emission timing control performed by the CPU 30 based on the control program 31a will be described with reference to the flowchart of FIG.

First, when the power switch is turned on, the CP
Initial processing such as clearing of the memory built in U30 and setting of I / O ports is performed (step 100). Then, the process waits until any switch is activated (step 101). The switches include a self-timer switch, a zoom switch, etc., which are not shown, in addition to the shutter button 11 and the selection dial 12.

Next, when any switch is activated (step 102), it is detected which switch is activated (step 103), and in the case of a switch other than the shutter button 11 and the selection dial 12, that switch is activated. Processing is performed for each switch (step 104). Well, step 1
When the switch detected in 03 is the selection dial 12 (step 105), the selection of the distance measuring point by the selection dial 12 is executed (step 106).

After that, when it is detected in step 103 that the shutter button 11 is half-pressed, the remaining amount of the power supply battery is checked (step 107). continue,
A signal from the CPU 30 is given to the photometric unit 20, and the photometric unit 20 measures the luminance within the photographing visual field (step 10).
8). Then, the signal from the CPU 30 is transmitted to the multipoint distance measuring device 3
5, the distance to the main subject is measured (step 109). Then, from the distance measured in step 109 and the focus detection point selected in step 106, the CPU
At 30, a replenishment value K for compensating for the insufficient light quantity due to the light distribution characteristic of the strobe is determined (step 110).

This supplementary value K is stored in the CPU 30 as a table having the position of the main subject and the subject distance as parameters.
Prepare in advance. Further, the replenishment value K may be changed discretely or continuously. Then, the apex value (BV) of the external light luminance and the apex value (SV) of the film sensitivity obtained in step 108 are substituted into the following equation to obtain the exposure value E which is the control value of the shutter 21.
V is calculated (step 111). This is called AE calculation.

EV = SV + BV ... By the calculation of the EV value, the combination of the shutter speed and the aperture value for obtaining the exposure amount necessary for photographing is determined. Next, an AV value for determining the timing of flashing the strobe 18 is calculated (step 112). This is called FM (flashmatic) operation. The AV value is a value corresponding to the opening area of the shutter 21 when the strobe 18 is made to emit light. In other words, when the AV value is obtained, it is possible to know when the opening area where the shutter 21 is started and gradually increases to make the strobe 18 emit light. Therefore, the emission timing of the strobe 18 is determined from the AV value. You can ask.

To calculate the AV value, first, step 109
The DV value and the GV value are calculated by substituting the distance (D) to the main subject and the guide number (No. _{DV = -2log 2 D ... GV =} 2log 2 GNo. ... Next, the reference correction table 31 written in the ROM 31.
An OFS value, which is a correction value, is obtained based on b. The reference correction table 31b is a correction table in which the brightness in the shooting field of view and the distance to the main subject (subject distance) are parameters, and is a correction value at the strobe optical axis, that is, at the center position of the shooting field of view. An example thereof is shown in FIG.

The reference correction table 31b shown in FIG. 7 shows the brightness in the field of view (.about.B1, B1.about.B2, B2.about.B3).
The distance to the main subject is (~ D1, D1 ~ D2, D2 ~ D3, D3 ~) and is divided into 4 steps from B3 ~).
It is divided into stages (B1 <B2 <B3, D1 <D
2 <D3). Then, the OFS value, which is a correction value of the exposure amount by the strobe 18, is finely assigned for each step. Basically, when the external light brightness is B1 or less, the exposure amount is insufficient only by the external light brightness, and therefore the correction value OFS = 1 is assigned such that the exposure amount by the strobe 18 does not decrease. When the external light brightness is B1 or more, the correction value OFS for reducing the exposure amount by the strobe 18 is 1/2.
~ 1/8 is allocated. The amount of decrease at this time is adjusted to be large when the subject distance is short.
The distances D1, D2, and D3 are, for example, D1 =
1.3m, D2 = 2m, D3 = 9m,
The strobe exposure amount is switched at these distances (hereinafter, this distance is referred to as a reference switching distance).

Then, the OFS value can be obtained by using the reference correction table 31b based on the luminance within the field of view measured in step 108 and the distance to the subject measured in step 109. For example, when the subject distance is between the reference switching distances D1 = 1.3 m and D2 = 2 m and the brightness is between B2 and B3, the reference correction table 31b
Therefore, OFS = 1/4. If the subject distance is D3 = 9 m or more and the brightness is between B1 and B2,
FS = 1.

Now, the FL value can be obtained by substituting the OFS value thus obtained and the K value obtained in the above-mentioned step 110 into the following equation: FL = log ₂ OFS · K. The formula,
DV value, GV value, FL obtained by
The AV value is obtained by substituting the value and the film sensitivity (SV) into the following equation AV = GV + SV + DV + FL-5 ... (Step 11)
2). The correspondence between the film sensitivity and the SV value is ISO
Are 100, 200, 400, 800, 1600 ... SV5, 6, 7, 8, 9 ...

Next, the shutter button 11 is further pressed from the half-depressed state until the state is fully pressed (steps 113 and 114), and the finger is released from the shutter button 11 without being fully pressed. When the process returns to the original, the process is returned to the process of step 101. When the shutter button 11 is fully pressed, the shutter 21 is opened and closed to take a picture. The opening / closing control of the shutter 21 is performed based on the EV value calculated in step 110. Then, the strobe light 18 is emitted at the timing when the opening area of the shutter 21 reaches the AV value calculated in step 111 (step 115). The light emission of the strobe 18 provides sufficient exposure for photographing.

After the shutter 21 is closed, the film is fed (step 116) and the strobe 18 is charged (step 117). Then, while the shutter button 11 is half-pressed, the processing is waited (step 118), the finger is released from the shutter button 11, and the shutter button 1 is released.
After 1 is returned to the original, the process is returned to step 101. In the present embodiment, instead of the conventional strobe light control that is set so that the optimal exposure amount is set in the center of the shooting field of view, the light distribution characteristics of the strobe are taken into consideration to determine the position of the main subject within the shooting field of view. Correspondingly, by supplementing the exposure amount by the strobe, variations in the irradiation light amount are compensated and a good exposure amount is obtained.

Next, the relationship between the exposure amount by the strobe 18 adjusted based on the reference correction table 31b and the exposure amount by the external light in the photographing field will be described with reference to the graphs of FIGS. These graphs show that the film sensitivity is IS.
In the case of O100 (SV = 5), the main subject is located in the center of the field of view, and the reference switching distances in the reference correction table 31b (to D1
, D1 to D2, D2 to D3, D3 to). When the position of the main subject is outside the center of the visual field, the supplementary value K described above is added to these graphs. When the replenishment value K is extremely large, such as when the strobe irradiation light amount has a light distribution characteristic that extremely decreases toward the periphery of the visual field, the strobe exposure amount is set to the maximum strobe exposure amount. Although not possible, it is conceivable to adjust the exposure as much as possible within that range.

FIG. 8 is a graph showing the relationship between the exposure amount by the strobe 18 and the exposure amount by external light when the distance to the main subject is D1 or less. As shown in the same figure, when the external light brightness is BV4 or less, the time for which the shutter 21 is open becomes the camera shake prevention limit and is constant. Therefore, the external light alone cannot provide 100% exposure necessary for shooting. . That is, B
V4 is the limit brightness at which so-called AE automatic control can be performed.

Therefore, the exposure amount of the external light continues to increase until the external light brightness reaches BV4. And the external light brightness is BV
When it becomes 4 or more, the AE automatic control works to control the shutter 21, and the exposure amount by the external light is adjusted to maintain 100%. Therefore, when the external light brightness is BV4 or higher, the exposure amount by the external light is constant. On the other hand, the exposure amount by the strobe 18 is 100% of the exposure amount required for photographing when the external light brightness is B1 or less, and as the external light brightness increases, .about.B1, B1 to B2, B2 to B3. , B3 to outside light luminance, OFS = 1, OFS = 1 /
2, OFS = 1/4 and OFS = 1/8 are assigned to the reference correction table 31b.

The total exposure amount for exposing the film is represented by the sum of the exposure amount by the external light and the exposure amount by the strobe.
In a region where the external light brightness is lower than BV4, the exposure contribution amount by the strobe is switched so as to decrease in the vicinity (B1) where the exposure contribution amount by the external light gradually increases. That is, at the switching brightness B1 in FIG. 8, switching control is performed to reduce the exposure contribution amount by the strobe to 50%.
This prevents the total exposure amount from excessively exceeding the appropriate exposure amount. Incidentally, the exposure amount by the strobe and its switching brightness are determined so that the total exposure amount always satisfies the appropriate exposure amount.

Further, also in the area of the external light luminance of BV4 or higher, the exposure amount by the strobe 18 gradually decreases as the external light luminance increases. That is, B1 to B2
Up to (BV6), the exposure contribution amount by strobe is 50%,
In B2 to B3, the exposure contribution by strobe is 25%,
The exposure contribution amount of 3 to 3 is 12.5%, which is gradually reduced.

Even if the external light brightness is high, if the flash 18 emits light so that the exposure amount is constant, the ratio of the light amount of the background to the main subject is reduced, and a photograph with a dark background is taken. . In the present embodiment, the exposure amount by the strobe 18 decreases stepwise as the external light brightness increases, and therefore the light amount ratio of the background to the main subject does not decrease even when the external light brightness is high. Therefore, a photograph is taken in which the background is not dark even under high brightness, and the atmosphere of the photograph is not impaired. As will be described later, even when the distance to the main subject is D1 or more, the exposure amount by the strobe 18 is adjusted to decrease stepwise as the external light brightness increases, so the distance to the main subject is long. However, the same effect can be obtained.

When the distance to the main subject is as short as D1 or less, the exposure amount by the strobe 18 when the external light luminance is B4 or more is extremely small (exposure contribution amount 12.
5%). This is because the main subject occupies a larger area than the background when shooting a short-distance subject, and the balance of the amount of light on the main subject surface and the background is upset, making it easier for the main subject to appear as a white photograph. In this embodiment, since the amount of light emitted by the strobe light is controlled to be extremely small when the short distance and the external light brightness are high, the balance between the main subject surface and the background is maintained. , The main subject will not be a white photograph.

In FIG. 9, the distances to the main subject are D1 and D2.
7 is a graph showing the relationship between the exposure amount of the strobe 18 and the exposure amount of external light in the case of the interval. From the graph in the figure,
The amount of exposure by external light is the same as the graph in FIG. On the other hand, the exposure amount by the strobe 18 is the same as the graph in FIG. 8 when the external light luminance is B2 or less, but the exposure amount by the strobe 18 is further reduced by 1 even if the external light luminance becomes B3 or more. This is different from the graph of FIG. 8 in that detailed processing such as reduction to / 2 is not performed.

This is because the distance to the main subject is D1 and D
Between the two, when the external light brightness becomes higher than B3,
This is because the problem that the balance between the amounts of light on the main subject surface and the background is lost does not occur. Therefore, when the external light brightness is B3, the exposure amount by the strobe 18 is 1 /
No detailed processing such as reduction to 2 is performed.

In FIG. 10, the distances to the main subject are D2 and D.
6 is a graph showing the relationship between the amount of exposure by the strobe 18 and the amount of exposure by external light in the case of 3; The graph of FIG. 9 differs from the graph of FIG. 9 in that the exposure amount by the strobe 18 is not reduced to 1/2 even if the external light brightness becomes B1. For this reason, the amount of exposure by the strobe having the external light brightness of B1 is double that in the graph of FIG. However, since the distance to the subject is D2 or more, which is even longer than that in the graph of FIG. 9, the problem of unbalanced light amounts on the subject surface and the background does not occur.

FIG. 11 is a graph showing the relationship between the exposure amount by the strobe 18 and the exposure amount by external light when the distance to the main subject is D3 or more. In the graph of the same figure, the exposure amount by the strobe 18 is 10 until the external light brightness becomes B2.
The point that the exposure amount is 0% is the same as that in FIG. 10, but when the external light luminance is B2 or more, the flash 18 stops emitting light (O
It is different from FIG. 10 in that it is controlled so as to perform FF. In this way, the stroboscopic light emission is stopped at the external light brightness of B2 or more because it is difficult for the stroboscopic light to reach when the distance to the main subject is as long as D3 or more, and when the external light brightness is as high as B2 or more, the strobe light 18 is emitted. This is because even if the emission of light is stopped, it has almost no effect on photography.

In the present embodiment, the reference correction table 31b shown in FIG. 7 has been described, but the form of the correction table is not limited to this, and more detailed steps are provided for the external light luminance classification and the distance to the main subject. Or vice versa,
It may have a smaller number of stages than the reference correction table 31b shown in FIG. The case where the film sensitivity is ISO100 has been described above, but similar effects can be obtained for other sensitivities by sliding the BV value.

In the present embodiment, when the position of the main subject is outside the center of the visual field, these FIGS.
The above-mentioned supplementary value K is added to the graph. The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the present embodiment, as shown in FIG. 2, the exposure amount is adjusted by slightly shifting the light emission timing of the strobe 18 from the shutter timing, but the light emission amount itself is changed by keeping the light emission timing of the strobe 18 constant. The exposure amount may be adjusted accordingly.

Although the distance to the main subject is measured by the active method, the passive method may be used.

[0056]

As described above, according to the camera with a built-in strobe according to the present invention, the position of the main subject in the photographing field of view is recognized by the multipoint distance measuring means, and the distance to the main subject is measured. Since the exposure amount of the image surface by the strobe light is controlled based on the distance and the position, it is possible to correct the variation in the exposure amount due to the strobe light distribution characteristics, and regardless of the position of the main subject, It is always possible to take good pictures.

Further, the amount of stroboscopic light emitted to the distance measuring point measured by the multipoint distance measuring means is insufficient depending on the strobe light distribution characteristic with respect to the amount of stroboscopic light irradiated to the distance measuring point at the center of the photographing field. The amount of deficiency is calculated, and the exposure of the strobe is corrected to compensate for the deficiency so that the exposure of the strobe irradiated to the main subject is not too small. In such a case, there is no shortage of exposure, and an appropriate amount of exposure can be obtained on the image plane.

Furthermore, the exposure amount replenishment value for replenishing the insufficient amount is preset for each distance measuring point of the multi-point distance measuring means based on the stroboscopic light distribution characteristic, so that the distance measuring distance measured by the multi-point distance measuring means is set. It is possible to instantly and easily control the exposure amount of the strobe by applying the above-mentioned exposure amount supplement value to the point.

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of an embodiment of a camera with a built-in flash according to the present invention.

FIG. 2 is a diagram showing an example of an arrangement of AF sensors in a viewfinder field.

FIG. 3 is a time chart showing the relationship between shutter opening timing and strobe light emission timing.

FIG. 4 is a diagram showing an example of strobe light distribution characteristics.

FIG. 5 is a flowchart showing a processing flow of strobe light emission timing control.

FIG. 6 is a block diagram showing a specific configuration for performing strobe light emission timing control.

FIG. 7 is a diagram showing an example of a reference correction table.

FIG. 8 is a diagram showing the relationship between the amount of exposure by a strobe and the amount of exposure by external light within the field of view when the distance to the main subject is D1 or less.

FIG. 9 is a diagram showing the relationship between the amount of exposure by a strobe and the amount of exposure by external light within the field of view when the distance to the main subject is D1 to D2.

FIG. 10 is a diagram showing the relationship between the amount of exposure by a strobe and the amount of exposure by external light within the field of view when the distance to the main subject is D2 to D3.

FIG. 11 is a diagram showing the relationship between the amount of exposure by a strobe and the amount of exposure by external light within the field of view when the distance to the main subject is D3 or more.

[Explanation of symbols]

 10 ... Camera body 12 ... Selection dial 13 ... Shooting lens 14 ... Lens barrel 15 ... Projector (multi-point distance measuring means) 16 ... Finder 17 ... Light receiver (multi-point distance measuring means) 18 ... Strobe 20 ... Photometer 21 ... Shutter 30 ... CPU 31a ... Control program 31b ... Reference correction table

Claims (6)

[Claims] 1. A multipoint distance measuring means for measuring a distance to a distance measuring point where a main subject is present among a plurality of distance measuring points in an imaging field of view, a distance measured by the multipoint distance measuring means, and A camera with a built-in strobe, comprising: strobe light control means for controlling a strobe image plane exposure amount based on the positions of the distance measuring points measured by the multi-point distance measuring means. 2. A photometric means for measuring the brightness within the photographing field of view, and a multipoint distance measuring means for measuring the distance to a distance measuring point where a main subject is present among the plurality of distance measuring points within the photographing field of view. Assuming that the reference external light luminance is the external light luminance at which optimum exposure is obtained with a predetermined shutter opening time, and the exposure amount at this time is the standard exposure amount, the reference external light luminance is based on the luminance measured by the photometric means. An automatic exposure mechanism that opens and closes the shutter that also serves as the diaphragm blade so as to obtain the standard exposure amount when shooting under external light with the above brightness, and emits light in conjunction with the opening and closing operation of the shutter,
A strobe light control unit for controlling the strobe image plane exposure amount based on the brightness measured by the photometry means, the distance measured by the multipoint distance measurement means, and the position of the distance measurement point measured by the multipoint distance measurement means. A camera with a built-in flash. 3. The strobe light control means sets a strobe light amount applied to a center distance measuring point in the photographing field,
A shortage amount of how much the strobe light amount irradiated to the distance measuring point measured by the multipoint distance measuring means is insufficient due to the strobe light distribution characteristic is obtained, and the strobe image plane exposure amount is corrected based on the shortage amount. The camera with a built-in strobe according to claim 1 or 2, characterized in that. 4. A photometric means for measuring the brightness within the photographing field of view, and a multi-point distance measuring means for measuring the distance to a distance measuring point where a main subject is present among the plurality of distance measuring points within the photographing field of view. Assuming that the reference external light luminance is the external light luminance at which optimum exposure is obtained with a predetermined shutter opening time, and the exposure amount at this time is the standard exposure amount, the reference external light luminance is based on the luminance measured by the photometric means. An automatic exposure mechanism that opens and closes the shutter that also serves as the diaphragm blade so as to obtain the standard exposure amount when shooting under external light with the above brightness, and emits light in conjunction with the opening and closing operation of the shutter,
Strobe light control means for controlling the strobe image plane exposure amount based on the brightness measured by the photometry means, the distance measured by the multipoint distance measurement means, and the position of the distance measurement point measured by the multipoint distance measurement means. Wherein the strobe light control means, when the luminance outside the reference light or the luminance in the vicinity thereof is the strobe switching luminance, when the luminance measured by the photometric means is lower than the strobe switching luminance, the strobe light alone is used as the standard. If the exposure amount by the strobe is controlled so that the exposure amount is obtained and the exposure amount by the strobe light at this time is set as the reference strobe exposure amount,
When the brightness measured by the photometric means is equal to or higher than the flash switching brightness, the exposure amount by the flash light is controlled to be gradually decreased from the reference strobe exposure amount as the brightness measured by the photometric means becomes higher. At the same time, to what extent the stroboscopic light quantity irradiated to the distance measuring point measured by the multipoint distance measuring means is insufficient due to the stroboscopic light distribution characteristic with respect to the stroboscopic light quantity irradiated to the central distance measuring point in the photographing field of view. Of the exposure amount by controlling the exposure amount by the strobe light that gradually decreases from the reference strobe exposure amount so as to replenish the deficit amount, and the exposure by the strobe light irradiated to the distance measuring point is controlled. A camera with a built-in flash that is designed so that the amount is not too small. 5. The strobe light control means increases the amount of reduction for stepwise reducing the exposure amount by the strobe light as the distance measured by the distance measuring means becomes shorter. 4. Built-in flash camera. 6. The strobe light control means presets an exposure amount replenishment value for replenishing the deficiency amount for each of the plurality of distance measuring points based on the light distribution characteristic of strobe light emission for each measuring point. 5. The camera with a built-in strobe according to claim 3, wherein the strobe image plane exposure amount is corrected by the exposure amount replenishment value for the distance measuring point measured by the multipoint distance measuring means. .