JP2001005065A - Photographing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize automatic exposure control with high accuracy in normal FP light emission (flashlight is repeatedly emitted at high speed) even though arithmetic operation time performed from the finish of preliminary FP light emission to the start of photographing is shortened. SOLUTION: This system includes a photodetector 11 measuring the luminance of normal light at the time of non-illumination and the luminance of a subject at the time of FP light emission, a light emitting tube 13 capable of the FP light emission, a light emitting tube driving circuit 12 driving the tube 13, and a control circuit 6 controlling exposure by measuring the luminance of the subject by the photodetetor 11 while controlling the circuit 12 in accordance with a subject distance and the luminance of the normal light so that the tube 13 may perform the FP light emission to illuminate the subject before photographing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographing system for photographing using auxiliary illumination light such as a flashlight.

[0002]

2. Description of the Related Art Conventionally, a photographing system of this type has a flashlight as a supplementary illumination light which can be used even when a high-speed shutter is used, such as a daytime synchro, in a camera using a focal plane shutter. There has been known a device that uses an auxiliary light capable of continuously emitting light (abbreviated as flat light emission, FP light emission, etc.) by repeatedly lighting the device (Japanese Patent Laid-Open No. 57-10 / 1982).
No. 5726).

[0003]

However, in the above-mentioned prior art, the exposure determination at the time of photographing using this FP emission is calculated differently from that of a flashlight or the like that performs normal flash emission, and the intensity of the FP emission and , The distance to the subject,
It was complicated using the brightness of the subject. In addition, there is a problem that the error is increased when the distance detection error is large.

Japanese Patent Application Laid-Open No. Hei 9-43670 discloses a method in which photometry is performed under preliminary FP light emission, and at the time of main FP light emission, 2 ^G times the peak value at the time of preliminary FP light emission (the main FP light emission is G stages stronger than the preliminary FP light emission). (Emission intensity), but it is necessary to finely control the peak value of FP emission.

An object of the present invention is to solve the above-mentioned problems and to provide a photographing system capable of performing highly accurate automatic exposure control with a simple configuration.

[0006]

According to a first aspect of the present invention, there is provided a photometric unit for measuring the brightness of a subject, and an exposure value at the time of photographing is calculated based on an output of the photometric unit. An exposure calculating unit (S7), an auxiliary lighting unit (S9, S14) capable of repeatedly emitting light at a high speed and capable of emitting FP light, and a light metering unit (S5) that emits light when photographing the auxiliary lighting unit. FP emission at the same intensity (S4, S
And 6) an illumination control unit.

According to a second aspect of the present invention, in the imaging system according to the first aspect, the illumination control unit changes the intensity of FP emission of the auxiliary illumination unit according to an imaging distance (S
3, Dist in FIG. 4).

According to a third aspect of the present invention, in the photographing system according to the first aspect, the illumination control unit emits FP light of the auxiliary illumination unit according to the luminance of the subject measured by the photometry unit when the illumination is not performed. Is changed (S3, Bv0 in FIG. 5).

[0009]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a camera according to an embodiment of the present invention. In the camera of the present embodiment, the light beam that has passed through the photographing lens 1 is bent by the quick return mirror 3 via the stop 2, and forms an image on the diffusion screen 7 once. Thereafter, the light reaches the eyes of the photographer through the pentaprism 8, the eyepiece 9, and the like.

On the other hand, a part of the light beam diffused by the diffusion screen 7 is transmitted to the pentaprism 8 and the photometric lens 1.
0, the image is re-imaged on the photometric light receiving element 11. At the time of photographing, the aperture 2 is stopped down to a predetermined value, and at the same time, the quick return mirror 3 is flipped up. Then, the focal plane shutter 4 travels in the order of the shutter first curtain 41 and the shutter rear curtain 42 to form a light beam on the film surface 5.

The control circuit 6 is a circuit for calculating an exposure value (aperture value and shutter time) at the time of photographing based on the luminance of the subject measured by the photometric light receiving element 11. Of the focal plane shutter 4 (not shown). Further, the control circuit 6 generates a signal for controlling the auxiliary lighting by emitting light at high speed (hereinafter referred to as preliminary FP emission and main FP emission) at the time of photometry and exposure, and controls the arc tube driving circuit 12. Through this, the arc tube 13 emits FP light.

Next, based on the flowchart of FIG.
The operation of the present embodiment will be described. When a shutter release button (not shown) is pressed, a routine shown in FIG. 2 is started. Here, an example of a shutter priority automatic exposure in which the shutter time is set in advance and the aperture value is automatically determined based on the subject brightness will be described.

In step 1, an object distance Dist is obtained. In step 2, the steady light brightness Bv0 is obtained. In step 3, the intensity FP of the FP emission is calculated using the following equation. Ifp = I0 * Kd (Dist) * Kb (Bv0) (1) where I0 is the maximum emission intensity. FP intensity I
fp will be described later in detail.

In step 4, the preliminary FP emission of the arc tube 9 is started at the intensity Ifp. In step 5, the object brightness Bv is obtained. Here, three to four photometric values are acquired, and the average value is set as the Bv value. In step 6,
The preliminary FP emission ends. Preliminary FP light emission will also be described later in detail.

In step 7, the apex value Av of the aperture is obtained from the following equation based on the subject brightness Bv, the apex value Sv of the film sensitivity, and the apex value Tv at the time of the shutter being set in advance. Av = Bv + Sv-Tv (2) In step 8, the aperture is narrowed down to the mirror value and the Av value determined in step 7.

In step 9, the FP emission is again reduced to the intensity I.
Start at fp. In step 10, the running of the front curtain 41 of the shutter is started. In step 11, it is determined whether or not the film is exposed only for the set shutter time. If the set shutter time has elapsed, the process proceeds to step 12.

In step 12, the rear curtain 42 of the shutter
Start running. In step 13, it is determined whether or not the rear shutter curtain 42 has finished traveling and whether or not the film surface has been completely shielded from light. If the traveling of the shutter rear curtain 42 has ended, the process proceeds to step 14. In step 14, the FP emission ends, and this routine ends.

Next, the auxiliary light control operation of the preliminary FP light emission and the main FP light emission according to the present embodiment will be described in more detail with reference to FIGS. FIG. 3 is a time chart illustrating the operation of the camera according to the embodiment of the present invention.
When a shutter release button (not shown) is pressed,
Prior to photographing (S10-S13), the FP of the arc tube 13
Light emission is started (S4), and the subject is illuminated. Here, the intensity of the FP emission is set in the arc tube drive circuit 12 based on the set distance information of the photographing lens 1 and the subject brightness.

First, the luminance (Bv0) of the subject is measured by the photometric light receiving element 11 between t1 and t2. However, the measurement is started after the FP emission is stabilized, and the luminance is measured three to four times and the photometric values are averaged in order to improve the accuracy of the photometric measurement. When the photometry of the subject brightness is completed (t2
), The preliminary FP emission is immediately terminated (S6).

Next, at the time t2 to t3, an exposure calculation for determining the aperture value of the aperture 2 at the shutter time of the shutter 4 is performed based on the photometric value of the object luminance and the film sensitivity (S7). The return mirror 3 is flipped up and the aperture 2 of the photographing lens 1 is stopped down based on the aperture value determined as described above (S8).

Thereafter, between t3 and t6, for photographing,
The FP emission of the arc tube 9 is started again (S9 to S1).
4). The emission intensity of the main FP emission is the same intensity (the same wave height) as the preliminary FP emission. First, at time t3, the shutter front curtain 41 is run (S10), and exposure of the film surface 5 is started. Next, when the film is exposed according to the shutter time determined as described above (S1).
1) At time t4, the rear curtain 42 of the shutter is driven (S12).

At time t6, when the travel of the shutter rear curtain 42 is completed and the exposure of the film is completed (S1).
3) The FP emission ends (S14). At the time of photometry, photometry under preliminary FP light emission is completed in a short time, so that the light emission available time at the time of photographing does not significantly decrease.

FIG. 4 is a diagram showing a function for setting the intensity of FP emission according to the subject distance. When the subject distance is short, if the intensity of the FP emission is the same as the long distance, the subject is illuminated brightly, so that the exposure is cut off and the background exposure becomes dark. Therefore, as shown in FIG. 4, the light emission intensity at a short distance becomes smaller than that at a long distance.
The light emission intensity coefficient Kd (Dis
t) is set. The subject distance Dist can be detected from the position of the taking lens 1.

FIG. 5 is a diagram showing a function for setting the intensity of the FP light emission in accordance with the brightness of the subject when there is no illumination. When the luminance at the time of non-illumination becomes dark, the brightness of the background becomes relatively dark as compared with the illuminated subject. Therefore, as shown in FIG. 5, the steady light luminance Bv at the time of non-illumination is set so that the light emission intensity becomes lower at the time of low luminance as compared with the time of high luminance.
The emission intensity coefficient Kb (Bv0) at 0 is set.

The emission intensity Ifp of the FP emission is determined by the product of the functions Kd and Kb according to the above-mentioned equation (1). As described above, the intensity of the FP emission during the pre-flash or the main flash is changed according to the shooting distance and the subject brightness, so that the background and the illuminated subject can be balanced in various shooting scenes. Excellent video can be taken.

According to this embodiment, the preliminary FP light emission is performed for a predetermined time before photographing, and the brightness of the object illuminated by the preliminary FP light emission is measured to determine the exposure control amount at the time of photographing. Therefore, regardless of the error of the distance even at the time of FP flash shooting, using the conventional photometric device as it is,
Optimal exposure control becomes possible.

(Modifications) Various modifications and changes are possible without being limited to the embodiment described above, and they are also within the equivalent scope of the present invention. (1) In aperture-priority automatic exposure, step 7 is a calculation for obtaining Tv. Tv = Bv + Sv-Av (3)

(2) In the program automatic exposure, the exposure value Ev may be obtained, and the Tv value and the Av value may be obtained from a combination P (Ev) determined in advance from the Ev value. Ev = Bv + Sv, (Tv, Av) = P (Ev) (4)

(3) In the case of continuous photographing or so-called bracket photographing in which the same subject is photographed by changing the shutter time and aperture little by little, the preliminary light emission for the second and subsequent frames is not performed. The second and subsequent imaging may be performed based on the first preliminary light emission data.

(4) Any camera using a focal plane shutter can be used for a digital camera. (5) After the FP emission metering switch is provided and the operations from S1 to S7 are performed, the shutter time and the aperture value may be displayed without releasing the shutter.

[0031]

As described above, according to the present invention,
Preliminary FP light emission is performed to detect the photometric value. With a simple configuration, high-precision FP light emission and automatic exposure are possible, and even when a high-speed shutter time is used, the accuracy of auxiliary lighting can be improved. Good auto exposure shooting becomes possible.

Further, since the intensity of the FP light emission at the time of the preliminary light emission and the exposure is changed according to the photographing distance and the luminance of the object, the background and the illuminated object are balanced in various photographing scenes. Excellent images can be taken.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a camera according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the camera according to the embodiment of the present invention.

FIG. 3 is a time chart illustrating an operation of the camera according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating a function for setting the intensity of FP emission according to a subject distance.

FIG. 5 is a diagram showing a function for setting the intensity of FP light emission in accordance with the luminance of a subject when there is no illumination.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photographing lens 2 aperture 3 quick return mirror 4 focal plane shutter 41 shutter front curtain 42 shutter rear curtain 5 film surface 6 control circuit 7 diffusion screen 8 pentaprism 9 eyepiece lens 10 photometric lens 11 photometric light receiving element 12 light emitting tube drive Circuit 13 Arc tube

Claims (3)

[Claims] A light meter for measuring the brightness of a subject; an exposure calculator for calculating an exposure value at the time of photographing based on an output of the light meter; An illumination control unit that causes the auxiliary illumination unit to emit FP light at the same intensity as the light emission at the time of shooting when performing photometry by the photometry unit;
An imaging system equipped with 2. The imaging system according to claim 1, wherein the illumination control unit changes the intensity of FP emission of the auxiliary illumination unit according to an imaging distance. 3. The imaging system according to claim 1, wherein the illumination control unit changes the intensity of FP emission of the auxiliary illumination unit according to the luminance of the subject measured by the photometry unit when the illumination is not performed. An imaging system characterized in that: