JPH1020357A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera for suppressing the measurement error between an exposure control photometric element and a strobe light adjusting photodetector and accurately controlling the exposure without making the camera large in size. SOLUTION: The exposure control photometric element 22 and the strobe light adjusting photodetector 23 are concentrically arranged around a photographic lens 11 and they are assembled integrally with a lens barrel part. Measuring light is made incident on the photometric element 22 and the photodetector 23 at the same angle to the optical axis of the photographic lens 11, then, one measured value becomes equal to the other. In front of the photometric element 22 and the photodetector 23, a belt like loop filter plate 25 is arranged so as to be freely rotated around the photographic lens 11, and L filters 26a and 26b, M filters 27a and 27b and D filters 28a and 28b having different light transmissivity are installed on the filter plate 25 side by side in the circular arc direction of the filter plate 25, and in the case of rotating the filter plate 25, the filters having the same light transmissivity are confronted with the photometric element 22 and the photoreceiving element 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a camera provided with a photometric element for controlling exposure and a light receiving element for strobe light control.

[0002]

2. Description of the Related Art Many recent cameras have an automatic exposure control device. The automatic exposure control device measures the subject brightness using a photometric element, and automatically adjusts the aperture value and the shutter speed according to the measured value. A camera equipped with this automatic exposure control device With, even a beginner can always shoot with proper exposure.

On the other hand, cameras with built-in strobe devices have become widespread so that photographing can be performed indoors or at night.
The strobe device illuminates the subject with the strobe light emitted from the strobe discharge tube and compensates for the lack of brightness of the subject. Some have an automatic dimming function to control. As a method of dimming the strobe light, the brightness of the object irradiated with the strobe light is measured by a light receiving element, and the emission of the strobe light is stopped at the moment when the temporal integration value of the measured value reaches a predetermined level. The method is mainly adopted.

In a camera incorporating both a flash device having such an automatic light control function and the above-described exposure control device, the exposure amount is adjusted by coordinating the two devices and a light receiving element for strobe light control is provided. The photometric element for exposure control is generally arranged side by side in the upper part of the front of the camera or in the periphery of the taking lens.

[0005]

However, if the light receiving element and the photometric element are simply arranged side by side, each element has a measuring light at a different angle with respect to the optical axis of the subject light imaged on the film. Is incident, a difference occurs between the two measured values even though the luminance of the same subject is measured. For this reason, the strobe light emission is stopped before the light amount of the subject light reaches a predetermined light amount,
Or, on the contrary, the irradiation amount of the strobe light becomes excessive, and the subject image cannot be formed with an appropriate exposure amount.

Further, a filter plate having a plurality of filters having different light transmittances is arranged on the front surface of the light receiving element and the photometric element, and the measured value of each element is arbitrarily increased / decreased to form an image on a film. There are cameras that can adjust the brightness of an image. However, in such a camera, generally, each filter unit is provided in a linear direction on a filter plate, and the filter unit inserted in the front of each element is switched by sliding the filter plate in the linear direction. Therefore, it is necessary to secure a space for evacuating the unused filter section around the light receiving element and the photometric element. In addition, when the number of filter units to be switched increases, a large space for retreating the filter plate is required.

In the case of a camera having a lens barrel holding a photographing lens protruding forward, the two light receiving elements and the photometric element are housed so that light incident on the lens barrel is not blocked by the lens barrel. It is necessary to project the part at substantially the same height as the lens barrel. If the filter plate is to be incorporated into such a camera, the front surface of the camera is projected over a wide range in consideration of the space for retreating the filter plate, and it is inevitable that the camera becomes larger.

The present invention has been made in view of the above circumstances, and suppresses a measurement error between a photometric element for exposure control and a light receiving element for strobe light control without increasing the size of a camera, and It is an object of the present invention to provide a camera capable of accurately controlling the camera.

[0009]

In order to achieve the above object, a camera according to the present invention has a photometric element and a light receiving element arranged concentrically around a taking lens. Also,
A band-shaped filter plate that is rotatable around the taking lens is arranged on the front of the photometric element and the light-receiving element, and a plurality of filter sections with different light transmittances are arranged in an arc direction on the plate surface of the filter plate. It is preferable to provide two sets of filter rows arranged side by side and to rotate and move the filter plate so that a filter portion having the same light transmittance faces the front surface of the photometric element and the light receiving element.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, in the center of the front of a camera body 10, a photographic lens 11, a photometric window 12 for exposure control, a light receiving window 13 for strobe light control, and a photographic lightness switch 14 are provided. Is provided. Camera body 1
A flash emission window 15 and a finder objective window 16 are provided above the front of the camera. Photometric window 12 and light receiving window 1
3 is provided concentrically around the photographing lens 11, and in the present embodiment, is provided side by side in the horizontal direction with the photographing lens 11 interposed therebetween. The photographing brightness changeover switch 14 is used to adjust the brightness of a subject image to be formed on the film. The "L" position for forming a bright subject image and the "M" position for normal brightness. , Can be switched to three positions, that is, a “D” position that darkens the subject image.

A grip 17 is provided on the side of the camera body 10.
The release button 18 is provided on the upper surface of the grip 17. When the release button 18 is half-pressed, photometry is automatically performed. Then, when the release button 18 is continuously depressed, the shutter speed and the aperture value of the program shutter are controlled in accordance with the photometric value, and shooting is performed with an appropriate exposure. When the photometric value has not reached the predetermined level, the strobe light is emitted from the strobe light emission window 15.

As shown in FIG. 3, a photometric element 22 is disposed on the back side of the photometric window 12, and a light receiving element 23 is disposed on the back side of the light receiving window 13. The photometric element 22 and the light receiving element 23 include a lens barrel 21 that holds the photographing lens 11.
It is integrated into one. As the photometric element 22, for example, a CdS element is used, measures the luminance of the subject, and outputs the luminance signal. As the light receiving element 23, for example, a phototransistor is used, and the strobe light emission window 1 is used.
5 receives the object light irradiated with the strobe light emitted from the light source 5, and outputs a light amount signal of a level corresponding to the light amount.
As described above, since the photometric window 12 and the light receiving window 13 are provided concentrically with the taking lens 11 as a center, the photometric element 22 and the As a result, the measurement light is incident at the same angle with respect to the optical axis 11a of the subject light formed on the film 24.

On the front surface of the lens barrel 21 in which the photometric element 22 and the light receiving element 23 are incorporated, a filter plate 25 is incorporated in an overlapping manner. As shown in FIG. 1, the filter plate 25 has a belt-like shape, and is incorporated so as to be rotatable around the photographing lens 11. On the filter plate 25, the photographing brightness changeover switch 14 is integrally formed, and the L filters 26 having different light transmittances are formed.
a, 26b, M filters 27a, 27b, and D filters 28a, 28b are provided side by side in the arc direction. As shown in FIG. 2A, when the photographing lightness changeover switch 14 is at the “L” position,
And L filters 26a and 26
b faces each other. When the photographing brightness changeover switch 14 is in the "M" position, the M filters 27a and 27b face the front surfaces of the photometric element 22 and the light receiving element 23 (see FIG. 3B), and when in the "D" position. The D filters 28a and 28b face each other (see FIG. 3C).

As shown in FIG. 4, the L filters 26a,
The M filter 27a and the D filter 28a are formed by changing the thickness of the filter plate 25. The thickness of the L filter 26a is T _L , the thickness of the M filter 27a is T _M , and the thickness of the D filter 28a is the when the T _D, is configured so as to satisfy the "T _L> T _M> T _D" following condition is. Since the light transmittance of each of the filters 26a, 27a and 28a is inversely proportional to the thickness thereof, the light transmittance of the L filter 26a is low, and the light transmittance of the L filter 26a is low, and the light transmittance of the D filter 28a is standard. Has a high light transmittance. The L filter 26b, the M filter 27b, and the D filter 28b have the same configuration.

FIG. 5 schematically shows an electric configuration of the camera. The exposure control device 31 includes a photometric circuit 32 and an exposure control circuit 33, and the strobe device 35 includes a strobe light emitting circuit 36 and a dimming circuit 37. When the main switch 38 is turned on, the light metering circuit 32, the exposure control circuit 33, the strobe light emitting circuit 3
6, and the dimming circuit 37 is supplied with power. When the main switch 38 is turned off, power supply to each circuit is cut off. When the main switch 38 is turned on, the flash light emitting circuit 36 immediately starts a charging operation,
A main capacitor (not shown) for storing electric charge for strobe light emission is charged.

The photometry circuit 32 has a half-press switch 41,
Further, a full-press switch 42 is connected to the exposure control circuit 33, and when the release button 18 is pressed, either the half-press switch 41 or the full-press switch 42 is short-circuited. The photometric circuit 32 includes a photometric window 12.
Is connected to a photometric element 22 provided behind the camera. When the half-press switch 41 is turned on, the photometric circuit 32 measures the subject luminance by the photometric element 22 and sends out a luminance signal to the exposure control circuit 33 and the strobe light emitting circuit 36. The exposure control circuit 33 converts the subject image with the proper exposure amount based on the luminance signal from the photometry circuit 32.
A shutter speed, an aperture value, and a target value of the light amount of the subject light for forming an image on the upper side are determined, and a target light amount signal is sent to the dimming circuit 37. When the full-press switch 42 is turned on by the release button 18, the exposure control circuit 33 controls the shutter speed and the aperture value of the program shutter.

When a program shutter is operated by the exposure control circuit 33, a synchronizing signal Sync
Is input to the strobe light emitting circuit 36 and the light adjusting circuit 37. The strobe light emitting circuit 36 causes the discharge tube 43 to emit light when the synchro signal Sync is input, whereby the strobe light is emitted from the strobe light emitting window 15. Note that when the subject luminance measured by the photometry circuit 32 has reached a predetermined level, the discharge tube 43 does not emit light even if the sync signal Sync is input to the strobe light emission circuit 36.

The light control circuit 37 is connected to a light receiving element 23 provided behind the light receiving window 13. Light control circuit 37
Is the light receiving element 23 when the synchronization signal Sync is input.
Then, the luminance of the object irradiated with the strobe light is measured, and when the temporal integration value reaches the target light amount determined by the exposure control circuit 33, a light emission stop signal is sent to the strobe light emitting circuit. The strobe light emission circuit 36 stops the light emission of the discharge tube 43 when the light emission stop signal is input.

The operation of the camera will be described below. When the main switch 38 is turned on, power is supplied to each circuit unit, and the camera enters a shooting standby state. The photographer
For example, to form a subject image with normal brightness, the photographing brightness switch 14 is switched to the “M” position. Thereby, the photometric element 22 and the light receiving element 2
M filters 27a and 27b face the front surface of 3 respectively.

When the photographer looks into the viewfinder, determines the photographing range and composition, and half-presses the release button 18,
The half-press switch 41 is turned on, and the photometry circuit 32 operates. Then, the photometric circuit 32 measures the luminance of the subject using the photometric element 22, and sends the luminance signal to the exposure control circuit 33 and the strobe light emitting circuit 36. Also, the exposure control circuit 3
3 determines a shutter speed, an aperture value, and a target value of a light amount of the subject light based on the luminance signal from the photometry circuit 32 to form a subject image with an appropriate exposure amount, and dimmes the target light amount signal. It is sent to the circuit 37.

Subsequently, when the photographer depresses the release button 18, the full-press switch 42 is turned on, and the exposure control circuit 33 controls the shutter speed and the aperture value of the program shutter so that the proper exposure is obtained.

If the subject brightness measured by the photometry circuit 32 is low and a sufficient exposure cannot be obtained, a sync signal Sync is input to the flash emission circuit 36 in conjunction with the release operation. At this timing, the discharge tube 43 emits light, and strobe light is emitted from the strobe light emission window 15 toward the subject. At the same time, the dimming circuit 37
Indicates the luminance of the object irradiated with the strobe light by the light receiving element 2
3, and the temporal integration value is used as the exposure control circuit 3.
At the moment when the target light amount determined in step 3 is reached, a light emission stop signal is sent to the strobe light emitting circuit 36. The strobe light emission circuit 36 stops the light emission of the discharge tube 43 at the moment when the light emission stop signal is input.

At this time, since the photometric element 22 and the light receiving element 23 are arranged concentrically with the taking lens 11 as the center, each of the elements 22 and 23 is provided with the light of the subject light imaged on the film 24. Measurement light is incident on the optical axis 11a at the same angle. Therefore, the distance from the subject to the light receiving surface is equal between the photometric element 22 and the light receiving element 23, and each element 2
There is no difference in the measured values according to 2, 23. As a result, the light amount of the subject light can be accurately adjusted with respect to the target light amount without excess or deficiency, and the subject image can be formed on the film 24 with an appropriate exposure amount.

When the photographer attempts to form an image of a subject that is brighter than usual, for example, the photographing lightness switch 14 is switched to the "L" position. Thus, the L filters 26a and 26b having low light transmittance face the front surfaces of the photometric element 22 and the light receiving element 23, respectively. The light incident from the photometric window 12 has the light amount of the L filter 2.
Since the light intensity is reduced while the light passes through 6a, the measured value of the photometric element 22 becomes a value lower than the actual subject luminance. Therefore, the exposure control circuit 33 controls the shutter speed and the aperture value so that the exposure becomes higher than the proper exposure. In addition, since the measured value of the light receiving element 23 is also lower than the actual luminance of the subject, the dimming circuit 37 outputs a light emission stop signal after the subject is irradiated with more strobe light than the target light amount. . As a result, an image of the subject brighter than the actual one is formed on the film 24.

To form a subject image darker than usual, the photographing lightness switch 14 is switched to the "D" position. As a result, the D filters 28a and 28b having high light transmittance face the front surfaces of the photometric element 22 and the light receiving element 23, respectively, so that the measured values of the photometric element 22 and the light receiving element 23 are lower than the actual subject luminance. High value. Therefore, if the photographing operation is performed in this state, the shutter speed and the aperture value are adjusted so that the exposure is lower than the proper exposure, and the amount of the strobe light applied to the subject is reduced. A dark subject image can be obtained.

[0026]

As described above, according to the present invention, the photometric element for exposure control and the light receiving element for strobe light control are provided concentrically around the taking lens. The measurement light enters at the same angle with respect to the optical axis of the subject light imaged on the film. Therefore,
The distance from the subject to the light receiving surface is equal between the photometric element and the light receiving element, so that there is no difference between the measured values of the elements. Thus, the light amount of the subject light can be accurately adjusted with respect to the target light amount without excess or deficiency, and a subject image with an appropriate exposure amount can be formed.

Further, on the front surface of the photometric element and the light receiving element,
A band-shaped filter plate that is rotatable and movable around the taking lens is arranged, and two sets of filter rows are arranged on the plate surface of the filter plate, in which a plurality of filter portions having different light transmittances are arranged in an arc direction. By rotating the filter plate, the filter part with the same light transmittance was opposed to the front of the photometric element and the light receiving element,
Compared with a conventional camera incorporating a filter plate that slides in a linear direction, the space for evacuating the unused filter unit can be reduced. Moreover, since the filter portions are arranged in the arc direction, the size of the filter plate does not increase even if the number of filter portions increases.

Further, the filter plate only needs to be large enough to cover the front surfaces of the photometric element and the light receiving element.
When the photometric element and the light receiving element are provided integrally with the lens barrel holding the taking lens, the diameter of the filter plate does not become larger than the diameter of the lens barrel. Therefore, the photometric element, the light receiving element, and the filter plate can be integrated into the front surface of the lens barrel without increasing the size of the camera.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory diagrams showing a relationship between a switching position of a photographing brightness changeover switch and a moving position of a filter plate, wherein FIG. 1A shows a state where the photographing brightness changeover switch is at an L position, and FIG.
(C) represents the state at the position D, and (C) represents the state at the position D.

FIG. 2 is a front view showing a camera embodying the present invention.

FIG. 3 is a schematic diagram illustrating a peripheral portion of a photographing lens illustrated in FIG. 1;

FIG. 4 is an explanatory diagram showing a configuration of a filter plate shown in FIG.

FIG. 5 is an explanatory diagram showing an electrical configuration of the camera.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 camera body 11 photographic lens 12 photometric window 13 light receiving window 14 shooting brightness changeover switch 22 photometric element 23 light receiving element 25 filter plate 26 a, 26 b L filter 27 a, 27 b M filter 28 a, 28 b D filter

Claims (2)

[Claims] 1. A camera comprising a photometric element for exposure control and a light receiving element for strobe light control, wherein a light receiving surface of each element is exposed from an opening formed in a front surface of a camera body. And a concentric circle centered on the taking lens. 2. A front surface of the photometric element and the light receiving element,
A band-shaped filter plate that is rotatable and movable around the taking lens is arranged, and two sets of filter rows are arranged on the plate surface of the filter plate, in which a plurality of filter portions having different light transmittances are arranged in an arc direction. 2. The camera according to claim 1, wherein a filter portion having the same light transmittance faces a front surface of the photometric element and the light receiving element by rotating the filter plate.