JPH04336535A - Bounce strobo device - Google Patents

Abstract

PURPOSE:To realize the photographing with the proper light exposure free from the light quantity shortage, even if the distance to a photographed body or the distance to a reflection article is long, in the bounce photographing. CONSTITUTION:A bounce strobo device is equipped with an La measurement part 15, Lb measurement part 16, and an nb measurement part 17, and the photographed body distance La, distance Lb to a reflection body, and the reflection rate nb of a reflection article are measured by a measurement part 17. When the light quantity shortage is estimated on the basis of the photographed body distance La, reflection body distance Lb, and the reflection rate nb, a bounce calculation part 22 controls a luminous circuit 26, and allows an auxiliary strobo luminous part 27 to illuminate.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bounce strobe device, and more particularly to a bounce strobe device that bounces strobe light at an appropriate exposure amount.

0002

[Prior Art] Conventionally, when taking photos using a strobe, when illumination light is directed directly at the subject, the so-called red-eye phenomenon occurs, in which the subject's eyes appear red, and the surface of the face is not clearly visible. There was a phenomenon where the subject was not captured or the shadow of the subject was reflected in the photo. For this reason, as described in JP-A-1-304434 and JP-A-1-304439, a bounce strobe device is used to emit strobe light toward the ceiling or wall using indirect lighting, and its reflection By illuminating the subject with light,
This is intended to prevent the above-mentioned phenomenon. The technology described in the above publication will be briefly explained with reference to FIG.

[0003] In FIG. 10, the distance from a strobe, that is, a camera equipped with a strobe, to an object is measured by La measuring means 1, which is a first distance measuring means for measuring the object distance La. On the other hand, the second distance measuring means Lb
The measuring means 2 measures the reflector distance Lb to the reflector (ceiling, etc.).

[0004] Then, the object distance La, the reflector distance Lb, and the focal length fT of the camera lens
From L, the geometrically optimal emission angle (bounce angle: θ
) and the irradiation angle (φx) are determined by the θ calculation means 3. Note that instead of the focal length fTL, (0.5×d)/f
An expression expressed as TL=tanφ0 may be used. In this case, φ0 is the shooting angle of view, and d is the diagonal length of the film. Here, only the results are shown as the following equation. θ= tan-1 {2Lb/La}

...(1) 2φx = 2[tan-1(2
Lb/La)

- tan-1 {(2Lb-La tanφ0)/L
a}] ...(2) However, it is assumed that the angle of incidence and the angle of reflection when the strobe light is reflected on the ceiling are equal. The light emission angle control means 4 controls the angle of the strobe light emission section 5 according to the bounce angle θ thus obtained.

[0005]

[Problems to be Solved by the Invention] As described above, the conventional bounce strobe device measures not only the distance to the subject but also the distance to the reflective object for reflecting light and the measured value of its reflectance. This was used to determine the bounce angle for indirect lighting and the strobe irradiation angle. This results in
Photography was being performed using a bounce strobe device (hereinafter abbreviated as bounce photography).

However, in such a bounce strobe device, the amount of light may be insufficient when the distance Lb to the reflector is large (far) or when the reflectance of the reflector is low.

The present invention was made in view of the above problems, and provides a bounce strobe that does not cause insufficient light intensity even when the distance to the reflector is long or the reflectance of the reflector is low when performing bounce photography. The purpose is to provide equipment.

[0008]

[Means for Solving the Problems] That is, the present invention includes a first distance measuring means for measuring a first distance between a camera and a subject, a reflector for reflecting strobe light toward the subject, and the camera. a second distance measuring means for measuring a second distance between the two; a reflectance measuring means for measuring the reflectance of the reflector; a detecting means for detecting the focal length or the imaging angle of view of the photographing lens; a bounce strobe device comprising: a control means for calculating a bounce angle and an irradiation angle of a strobe light emitting part based on the first distance, the second distance, the reflectance, and the output of the detecting means, and controlling the bounce angle and the irradiation angle based on the calculated values. The amount of strobe light that will reach the subject before firing is predicted based on the first distance, the second distance, and the reflectance, and if this amount of light is insufficient, or the bounce is controlled by the control means. a determining means that integrates the reflected light from the subject based on the light emission of the strobe device, and outputs light amount insufficient information when the integrated value does not reach a predetermined value;
An auxiliary strobe device that emits light directly toward the subject;
When the above determination means outputs insufficient light information,
The present invention is characterized by comprising an auxiliary strobe control means for controlling light emission of the auxiliary strobe device.

[0009]

[Operation] In the bounce strobe device of this invention,
Subject distance La, distance to reflector Lb, and reflectance nb
Therefore, if an insufficient amount of light is predicted in advance, strobe light is emitted from the auxiliary strobe device to compensate for the insufficient amount of light. Further, after direct photometry using light emission from the main strobe device, if the amount of light is insufficient, the auxiliary strobe device is further caused to emit light.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be explained with reference to FIG.

In the figure, 11 is a camera with a built-in strobe, 12 is a strobe light emitting unit whose light emitting direction and irradiation angle are variable, 13 is a subject, and 14 is a reflector such as a ceiling that reflects strobe light.

[0012] Here, the distance between the camera 11 and the subject is defined as La. Similarly, the distance between the camera 11 and the ceiling 14 is Lb, the reflectance of the ceiling 14 is nb, and the horizontal direction of the strobe light emitting unit 12 during normal shooting (bounce shooting) when using a bounce strobe device. The emission angle is θ, the strobe irradiation angle during bounce shooting is 2φx (half-angle φx), and the focal length of the photographing lens of camera 11 is fT.
Let it be L. Here, if the screen of the photographing lens is 2φ0 and the diagonal length of the photographic screen is d, then the relationship between φ0 and fTL is expressed as (0.5×d)/fTL=tanφ0. Then, from these subject distance La and reflector distance Lb, the optimum value θ of the light emission angle of the strobe light emitting unit 12 is determined using equation (1). Next, the first bounce strobe device according to the present invention based on the above principle will be described.
The configuration of this embodiment is shown in FIG.

[0013] The La measuring section 15, which is a first distance measuring means, measures the distance from the strobe, that is, the camera 11 having a built-in strobe, to the subject 13. This distance measurement method is usually performed by emitting light from an infrared LED and determining which position of a light receiving element such as a PSD the reflected light beam from the subject 13 is incident on. On the other hand, the Lb measuring section 1 which is the second distance measuring means
6 measures the reflector distance Lb to the reflector 14 such as the ceiling. The configuration of this Lb measuring section 16 is the same as that of the La measuring section 15.

The nb measuring section 17 is a means for measuring the reflectance nb of the reflector 14, and the PSD of the Lb measuring section 16 is
It is configured such that it can be determined from the ratio of the sum of the photocurrents due to the reflected light flux flowing to both poles of Lb and the measured value of Lb. Further, a light receiving element may be installed separately.

The fTL detection section 18 is means for detecting the current focal length fTL of the photographing lens in the zoom camera. Generally, it is composed of a so-called zoom encoder that performs detection by moving a sliding contact piece over a substrate having a gray code in conjunction with changing the focal length. The emitted light amount detection section 19 is a strobe light emitting section 13.
This means detects the amount of emitted light or charging energy by detecting the charging voltage of the main capacitor.

Further, the θ calculation section 20 calculates the optimum light emission angle (bounce angle) θ from the object distance La measured by the La measurement section 15 and the reflector distance Lb measured by the Lb measurement section 16. It is a means of finding it geometrically. Generally, it is assumed that the angle of incidence on the ceiling and the angle of reflection during bounce photography are equal, and are determined from the relational expression (1) above, as in the known example. Of course, instead of formula (1), La, L
It is also possible to have a table of b and θ and calculate θ from the values of La and Lb.

[0017] The φx calculation unit 21 is connected to the La measurement unit 15 described above.
, La which is the output of the Lb measuring section and the fTL detecting section 18,
This is a means for geometrically determining the optimum irradiation angle 2φx from the values of Lb and fTL. As in the known example, this φx is calculated as follows: φx = [tan-1(2Lb/La)
- tan-1 {(2Lb-La tan
φ0)/La}]
= [tan-1(2Lb/
La)
−
tan-1 {(2Lb-(0.5d×La)/fTL
)/La}]...(3) It is determined from the following relational expression. Furthermore, in this φx, as well as θ, La, Lb,
It may be determined by referring to the fTL and φx tables.

The bounce calculation unit 22 calculates the above La, Lb,
nb, fTL and the output of the light emission amount detection unit 19;
This is to calculate whether the values of θ and φx obtained by the θ calculation unit 20 and the φx calculation unit 21 can be used as they are, taking other factors into consideration.

The light emission angle control section 23 controls the light emission angle of the strobe light emission section 12 based on the value of .theta. determined by the .theta. calculation section 20 or the bounce calculation section 22. In general,
The light emitting section is rotated by an actuator such as a motor until the value of a light emission angle encoder (not shown) reaches a predetermined value.

The irradiation angle control section 24 also controls the φx calculation section 21 or the bounce calculation section 23.
By moving the condensing lens 12a placed in front of the strobe light emitting unit 12 back and forth based on the value of x,
The irradiation angle is controlled to be φx. In general,
The condenser lens 12a is operated by an actuator such as a motor until the value of the irradiation angle encoder (not shown) reaches a predetermined value.
I'm trying to move it. Note that 25 is a light emitting circuit of the strobe light emitting section 12, and 26 is a light emitting circuit of the auxiliary strobe light emitting section 2.
7 light emitting circuit. Next, the operation of this embodiment will be explained.

When the camera 11 is pointed at the subject 13 and a desired focal length is selected by zooming, the fTL detection unit 1
8, the focal length fTL of the photographing lens is detected. Next, when the first release button is pressed, the La measuring section 15, Lb measuring section 16, and nb measuring section 17 operate to detect La, Lb, and nb. Based on the results, the θ calculation unit 20 and the φx calculation unit 21 calculate the optimal bounce angle and irradiation angle.

Here, the emission angle control unit 23 and the irradiation angle control unit 24 set the bounce angle and the irradiation angle so that the values of θ and φx calculated by the θ calculation unit 20 and the φx calculation unit 21 are obtained. do. When the shutter opens in conjunction with the second release of the camera, a trigger signal is sent from the light emitting circuit 25 to the strobe light emitting section 12. As a result, strobe light emission is started. Normally, proper balanced photography is possible with the above operations.

By the way, as the subject distance La becomes smaller, the bounce angle θ gradually approaches 90°. Therefore, if you photograph a person with θ approaching 90°,
A shadow appears under the nose, resulting in an unnatural photo. Therefore, when the subject distance La becomes smaller than a predetermined value, the bounce calculation unit 22 recognizes this and issues a command to the light emission angle control unit 23 to set the bounce angle θ to 90° or more than 90°. .

Shooting with θ set to 90° or more means that the strobe light is
The subject is illuminated with diffused light among the light beams emitted backward from the ceiling 14 and reflected by the ceiling 14 (Fig. 3
reference). Therefore, since the light beam is more horizontal than when illuminated with θ determined by the above equation (1), it is difficult to form a shadow directly below the nose.

[0025] Furthermore, if the output of the Lb measuring section 16 is greater than a predetermined value, that is, the value of Lb is very large, or if the Lb
cannot be measured, that is, if there is no ceiling, bounce photography on the ceiling is impossible. Such an output is detected by the Lb measuring section 1.
6, the bounce calculation unit 22 instructs the light emission angle control unit 23 to set a value of θ<0° to bounce on the ground according to the value of La. As a result, the strobe light emitting section 12 emits strobe light below the horizontal.

By the way, the energy (E1) required for bounce photography can be expressed using Laa, Lb, nb, and fTL in the following relationship. E1=A(La2+4Lb2)-1×n
b −1×fTL−2×FNO2 (4) Note that FNO represents the number of the photographic lens.

On the other hand, the energy (E2) that can emit light is
By detecting the charging voltage, the light emission amount detection unit 19
It can be calculated from If the relationship is E1 < E2, photographing is possible, but if the relationship is E1 > E2, the amount of emitted light is insufficient. Bounce calculation section 2
2 recognizes such a situation, by setting a value smaller than φx calculated by equation (2),
At least for subjects located near the center of the screen, it is possible to take appropriate photographs.

[0028] Here, it is assumed that the amount of light is expected to be insufficient with only the bounce strobe light. Then, the bounce calculation unit 22 instructs the light emitting circuit 26 to emit a necessary amount of light in order to cause the auxiliary strobe light emitting unit 27 provided separately from the main strobe light emitting unit 12 to emit light.

FIG. 4 is a block diagram showing another example of causing the auxiliary strobe light emitting section to emit light according to the second embodiment of the present invention. In this figure, the same parts as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

In FIG. 4, the integrating circuit 28 receives the light from the strobe light emitting unit 12 reflected by the subject using the light receiving element 29, and integrates the received light. In the case of a so-called direct metering strobe, which integrates the reflected light from the subject and outputs a flash stop command when the light intensity becomes appropriate, the bounce strobe (stroboscopic light emitting unit 12) Integrate the amount of light reflected by the subject. Then, only when the result still does not reach the appropriate value, the bounce calculation section 22 outputs a light emission command to the light emission circuit 26 in order to cause the auxiliary strobe light emission section to emit light.

In the figure, the light reflected from the object is transmitted to the light receiving element 2.
9, if the integration completion signal is not generated from the integration circuit 28, the bounce calculation section 22 outputs a light emission signal to the light emission circuit 26. As a result, the auxiliary strobe light emitting section 27 illuminates the subject with strobe light.

Further, when the auxiliary strobe light emitting section 27 becomes appropriate, the bounce calculation section 22 outputs a light emission stop signal to the light emission circuit 26 when an integration completion signal is generated from the integrating circuit 28. FIG. 5 is a circuit diagram showing the configuration of the direct photometry circuit.

In the figure, a feedback amplifier 281 is for applying an initial reference voltage Vref to an integrating capacitor 282 via an analog switch 281. 284 is an integrating amplifier for operating the SPD 285 with zero bias. The output of the integrating amplifier 284, together with the outputs of the voltage dividing resistors R1 and R2, is supplied to a comparator 286 that determines the completion of integration. The output of this comparator 286 is then output to the bounce calculation section 22.

Next, the operation of this direct photometry circuit will be explained. First, the analog switch 282 is turned off simultaneously with the opening of the shutter. Then, when the returned light from the strobe light emitting section is reflected by the subject or the light further reflected from the film surface enters the SPD 285, the output potential of the integrating amplifier 284 increases. When the potential reaches or exceeds the potential set by the voltage dividing resistors R1 and R2, the comparator 286 is inverted and an integration completion signal is transmitted to the bounce calculation section 22.

After the strobe light emitting section starts emitting light, a certain period of time (
For example, if the integration completion signal is not generated even after 10 msec) has elapsed, the bounce calculation section 22 outputs a light emission start signal to the light emitting circuit 26 for the auxiliary strobe light emitting section 27 to cause the auxiliary strobe light emitting section 27 to emit light. let Note that if the integration completion signal is generated while the auxiliary strobe light emitting section 27 is emitting light, this photometry circuit outputs a light emission stop signal to terminate the light emission of the auxiliary strobe light emitting section 27.

In the example shown in FIG. 6, the distance Lb to the ceiling 14
In addition to measuring the color of the ceiling 14, it also detects the color of the ceiling 14. A light emitter 30 having relatively flat spectral characteristics is emitted toward the ceiling 14, and the reflected light from the ceiling 14 is received by photodiodes PD1 and PD2 having different spectral reception characteristics, as shown in FIG. 7, for example. do. The outputs of PD1 and PD2 are input to a reflective object color detection circuit 31, where the color of the ceiling 14 is detected based on the output ratio of PD1 and PD2.

By inputting the output of this reflective object color detection circuit 31 to the bounce calculation section 22, if the ceiling has an extreme color such as red or blue, a warning or photography prohibition signal is sent from the bounce calculation section 22. It is also possible to output.

FIG. 8 shows a third embodiment of the invention. This third embodiment is not bounce photography;
A bounce strobe device is used during backlight imaging outdoors, and the backlight determination circuit 32 is provided with two photometric light receiving elements PDA and PDS.

As shown in FIG. 9, the photometric photodetecting elements PDA and PDS are arranged in the center of the photometric photodetecting element PDA. A backlight correction strobe that detects the backlight condition of a subject is well known, but the backlight is usually of high brightness. Therefore, in a lens-shutter camera, the strobe is emitted with a small aperture, so backlight correction is not effective enough. Therefore, when a backlight condition with high brightness is detected and this information is input to the bounce calculation section, φx is set to be smaller than the photographing angle of view. Then,
By concentrating the strobe light at the center of the screen, that is, near the subject, it becomes possible to perform effective backlight correction.

[0040]

As described above, according to the present invention, there is provided a bounce strobe device that does not cause insufficient light intensity even when the distance to the reflector is long or the reflectance of the reflector is low when performing bounce photography. can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a bounce strobe device according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of the bounce strobe device of the present invention.

FIG. 3: The bounce angle is 90 in the first embodiment of this invention.
It is a figure showing an example of the state where it is set to more than °.

FIG. 4 is a block diagram showing another example of causing the auxiliary strobe light emitting section to emit light in the second embodiment of the present invention.

FIG. 5 is a circuit diagram showing the configuration of a direct photometry circuit.

FIG. 6 is a diagram showing the configuration of a bounce strobe device according to a second embodiment of the invention.

7 is a spectral characteristic diagram of the photodiode shown in FIG. 6. FIG.

FIG. 8 is a diagram showing the configuration of a bounce strobe device according to a third embodiment of the invention.

9 is a diagram showing the arrangement of photometric light receiving elements PDA and PDS in FIG. 8; FIG.

FIG. 10 is a block diagram showing the configuration of a conventional bounce strobe device.

[Explanation of symbols]

11...Camera, 12...Strobe light emitting unit, 13...Subject,
14...Ceiling, 15...La measurement section, 16...Lb measurement section, 1
7...nb measurement section, 18...fTL detection section, 19...light emission amount detection section, 20...θ calculation section, 21...φx calculation section, 22
...bounce calculation section, 23...light emission angle control section, 24...irradiation angle control section, 25, 26...light emission circuit, 27...auxiliary strobe light emission section, 28...integration circuit.

Claims (1)

[Claims] 1. A first distance measuring means for measuring a first distance between a camera and a subject; and a second distance measuring means for measuring a second distance between the camera and a reflector that reflects strobe light toward the subject. a second distance measuring means; a reflectance measuring means for measuring the reflectance of the reflector; a detecting means for detecting the focal length or the imaging angle of view of the photographing lens;
In the bounce strobe device, the bounce strobe device includes a control means for calculating a bounce angle and an irradiation angle of a strobe light emitting part based on the distance, the reflectance, and the output of the detecting means, and controlling the bounce angle and the irradiation angle based on the calculated values. The amount of strobe light that will reach the subject before emitting light is predicted based on the first distance, the second distance, and the reflectance, and if this amount of light is insufficient, or based on the light emission of the bounce strobe device controlled by the control means. a determination means that integrates the reflected light from the subject and outputs insufficient light information when the integral value does not reach a predetermined value; an auxiliary strobe device that emits light directly toward the subject; A bounce strobe device comprising: auxiliary strobe control means for controlling light emission of the auxiliary strobe device when insufficient light amount information is output.