JP2003131284A - Camera provided with electronic flash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera provided with an electronic flash capable of obtaining a satisfactory print photograph without suffering overexposure even in the case of photographing an object of high brightness in an electronic flash photographing state. SOLUTION: This camera is provided with an electronic flash device having a first diaphragm, a second diaphragm with an aperture diameter larger than that of the first diaphragm, a photometric means for measuring object brightness, a switching means for switching the diaphragm to the second diaphragm when the photometric means detects that it is darker than prescribed brightness, and a dimming means for stopping electronic flash light emission when the received light quantity of the electronic flash reflected light from the object reaches prescribed received light quantity, and is further provided with the electronic flash provided with a light emission switching means for selectively switching whether to make the electronic flash device emit light and inhibiting a dimming operation by the dimming means in the case that the photometric means detects that it is equal to or brighter than the prescribed brightness while the light emission switching means is ready to perform electronic flash light emission.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a camera equipped with a strobe having light control means for adjusting the emission time of an arc tube by receiving strobe reflected light from a subject. . 2. Description of the Related Art In recent years, a camera, particularly a film unit with a lens, which is one of inexpensive cameras, has been remarkably developed and can obtain better pictures. An example of this is a film unit with a lens provided with a light control strobe. In a film unit with a lens,
Because of the simplicity of operation and low price, the conventional film unit with a lens has a single shutter speed,
The aperture remained open. By improving this, the F-number of the photographic lens is increased to extend the reach of the strobe light, making it more suitable for strobe photography, and switching to a small aperture at high brightness during the day. There is. Further, there is a film unit with a lens in which the strobe is used as a dimming strobe to improve the light emission and adjust the light emission time of an arc tube according to the amount of reflected light from a subject. According to this, the problem that overexposure occurs in short-distance stroboscopic photography in which the frequency of photography is high has been solved. [0004] In daytime shooting,
When a main subject such as a person is in a backlight state or in the shade of a tree, performing flash photography (daytime synchro photography) eliminates the lack of exposure of the main subject. If the strobe is a light control strobe, the main subject is always photographed with proper exposure regardless of the photographing distance. However, at the time of flash photography, the F
In a film unit with a lens in which the aperture is switched to make the value brighter, the brightness at which proper exposure can be obtained by the aperture and shutter speed is set to a value that assumes indoors. Excessive exposure will result. When printing is performed based on the negative film exposed in this manner, printing takes a long time to print and the work efficiency in the lab deteriorates. In addition, a normal printer averages the entire screen of the negative film by photometry. In this case, the image is printed with a slight underexposure, and the surrounding subject is over-exposed and the proper exposure is achieved, but the main subject, which is essential, is underexposed. In particular, when the main subject is a woman, the image is reflected on a black-and-white face, which is not preferable. SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and it is an object of the present invention to provide a camera equipped with a strobe capable of obtaining a good photograph without overexposure even when shooting with a strobe in a bright outdoor environment. It is an object of the invention. [0008] The above object is achieved by the following means. A first aperture, a second aperture having an aperture diameter larger than the aperture diameter of the first aperture, photometric means for measuring the subject brightness, and a second aperture when the photometric means detects that the brightness is lower than a predetermined brightness. A strobe device having switching means for switching to an aperture, light control means for receiving strobe reflected light from a subject by strobe light emission, and stopping strobe light emission when the amount of received light reaches a predetermined amount of received light;
Light-emission switching means for selectively switching whether the strobe device emits light or not, and when the light-emission switching means is in a state of performing strobe light emission, the light metering means detects that the light is brighter than a predetermined luminance. A camera provided with a strobe, wherein a light control operation by the light control means is prohibited in the case. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of a camera having a strobe according to the present invention is shown in FIGS. 1 to 4 with a lens having a light control strobe. This will be described in detail using a film unit. First, the external shape of a film unit with a lens provided with a light control strobe will be described with reference to a perspective view shown in FIG. On the front, a photographing lens 1, a finder window 2, a strobe light emitting unit 3 of a strobe device as a light emitting device,
A strobe switch lever 4, a photometric element to be described later, and an opening 5 for guiding light to a light receiving element for dimming are arranged. A release button 6, an exponent window 7, and a charging display window 8 are arranged on the upper surface. Is provided with a winding knob 9. here,
When performing flash photography, when the flash switch lever 4, which is a means for selectively switching the flash device to emit light or not, is slid rightward in the figure, an internal main switch is turned on, and the flash is charged. Starts, a photometric circuit (photometric means) described later is operated, and the aperture is switched according to the luminance of the subject. When the internal main capacitor is charged to a predetermined voltage, the charging state can be visually recognized by lighting the charging display window 8. To shoot, the release button 6 may be pressed. When the strobe switch lever 4 is slid rightward as shown in the figure,
The tip 4a projects rightward, and it can be easily determined that the flash photography state has been set. A high-sensitivity film of ISO 800 or higher is loaded in the lens-equipped film unit having the light control strobe. Next, the aperture switching mechanism will be described with reference to FIGS. FIG. 2 is a perspective view of an aperture switching mechanism for automatically switching the aperture according to the brightness of the surroundings in a flash photography state, FIG. 3 is a front view showing an aperture switching state by the aperture switching mechanism, and FIG. FIG. 3 is a circuit diagram of a strobe circuit provided with a drive circuit of a solenoid which is a drive device for driving an aperture switching mechanism. In FIG. 2, the diaphragm blades 51 and 52 are
The drive pin 54b of the drive shaft 54a of the solenoid 54 is inserted into the long holes 51a, 52a. The drive shaft 5 of the solenoid 54
4a, the drive pin 54b moves the elongated hole 51a,
It is configured to move in the inside 52a and switch between a state where a small aperture 56 shown in FIG. 3A is formed and a large aperture state where a fixed aperture hole 57 shown in FIG. 3B is exposed. When a small aperture 56 shown in FIG. 3A is formed on the aperture blade 51, the first photo sensor Ph1 which is a light receiving element for dimming prevents the strobe reflected light from entering the first photo sensor Ph1. A light-shielding portion 51b that shields the sensor Ph1 is provided. The drive shaft 54a of the solenoid LC is urged in one direction (the direction of the arrow in FIG. 2) by an urging member such as a spring, and is provided on the strobe switch lever 4 in a normal state where no strobe is used. Projection (not shown)
Thus, the movement is corrected to the end position of the movement range in the direction opposite to the direction of the arrow in FIG. 2 against the urging force of the urging member. Accordingly, the aperture blades 51 and 52 are located at positions where the small aperture 56 shown in FIG. 3A is formed in a normal photographing state without using a flash. When the strobe switch lever 4 is operated to move to the strobe use position, the strobe switch lever 4
The correction state of the solenoid 54 with respect to the drive shaft 54a is released, and the solenoid drive circuit described later is operated. When the subject brightness is low, the solenoid 54 is not energized by the solenoid drive circuit and the solenoid 54 is turned off, and the drive shaft 54a is moved by the urging member to the end of the moving range in the direction of the arrow in FIG. Moved to the position
The aperture blades 51 and 52 enter the large aperture state shown in FIG. 3B, and at the same time, move to the retracted position where the light shielding unit 51b does not shield the first photosensor Ph1. When the subject brightness is high, the solenoid 54 is energized to turn on the solenoid 54, and the drive shaft 54a is moved by the urging member in a direction opposite to the direction of the arrow in FIG. By moving to the end position, the aperture blades 51 and 52 enter the small aperture state shown in FIG. 3A, and the first photosensor Ph1 is shielded from light by the light shielding unit 51b. As described above, in the flash photography state, the solenoid 5 is driven by the solenoid driving circuit.
4 is automatically switched to the small aperture state shown in FIG. 3A by energizing (turning on), and is automatically switched to the large aperture state shown in FIG. Next, a flash circuit diagram of the flash device will be described with reference to FIG. First, the basic operation of the flash circuit diagram will be described. When the main switches S1 and S2 are turned on by an external operation, the current of the battery B becomes the resistance R
1 and starts oscillating by flowing to the transistor TR1.
The secondary side of the oscillation transformer T is boosted to a high voltage of 300 to 350V. The current on the secondary side is rectified by the diode D1, and the trigger capacitor CT and the main capacitor CM connected in series with the resistor R3 are charged. When the main capacitor CM is charged to a predetermined voltage, the light emitting diode DL connected in series with the resistor R2 lights up, indicating that shooting is possible. At the time of photographing, the trigger switch ST is turned on in conjunction with the opening operation of the shutter blade. Thereby, the trigger capacitor CT and the trigger switch S
T, the primary side of the trigger transformer TC, and the main switches S1 and S2 form a closed circuit, and the charges charged in the trigger capacitor CT are transferred to the trigger transformer T.
Discharge to the primary side of C. As a result, the trigger transformer T
Further high pressure is generated on the secondary side of C and applied to the trigger electrode of the xenon tube Xe, so that the ionized xenon atoms in the xenon tube Xe collide with the electrons ejected from the cathode and are excited, The xenon tube Xe emits light with the discharge of the main capacitor CM. Next, the dimming operation by the dimming means of the flash circuit will be described. When the trigger switch ST is turned on, a part of the electric charge of the main capacitor CM flows as a current i1 through the primary side of the trigger transformer TC and the trigger switch ST and flows to the resistor R3. After the trigger capacitor CT is discharged, a part of the electric charge of the main capacitor causes the current i2 to charge the trigger capacitor CT.
And flows to the resistor R3. Here, the resistance R3 and the resistance R
Since the Zener diode DT having the cathode on the side of No. 3 is connected in series, a current i obtained by adding the current i1 and the current i2 flows through the Zener diode DT. The first photosensor Ph1 and the capacitor CP connected in series are connected in parallel with the Zener diode DT. The connection between the first photosensor Ph1 and the capacitor CP is connected to the transistor T1 via the resistor R4.
It is connected to the base of R2, and the emitter of transistor TR2 is connected to the gate of thyristor S. The thyristor S is connected in series with the choke coil CC for the damper, and these are connected in parallel with the xenon tube Xe. Therefore, when the thyristor S is turned on, a current larger than the current flowing through the xenon tube Xe flows through the choke coil CC, the electric charge of the main capacitor CM is rapidly consumed, and the light emission of the xenon tube Xe is stopped. It has become. A current i flows through the Zener diode DT,
When a Zener voltage is generated at both ends of the Zener diode DT, a current flows through the first photosensor Ph1 according to the reflected light of the subject. If the shooting distance is short, the strobe light reflected by the subject becomes strong, and the first photo sensor P
The current flowing in h1 increases. Therefore, the capacitor C
Charging to P is quick. On the other hand, if the shooting distance is long, the strobe light reflected by the subject becomes weak, and the current flowing through the first photosensor Ph1 becomes small. Therefore, charging the capacitor CP is slow. As a result, if the distance is short, the transistor TR2 is turned on quickly and the thyristor S is also turned on quickly, so that the charge of the main capacitor CM rapidly changes during the light emission of the xenon tube Xe. The xenon tube Xe stops emitting light as soon as it is consumed by the CC.
On the other hand, if the distance is long, the transistor TR2 is turned on slowly, and the thyristor S is also turned on slowly.
The xenon tube Xe stops emitting light later. Therefore, even when the aperture is fixed, the reflected light from the subject changes according to the shooting distance and the total light emission amount of the strobe changes, so that a substantially constant exposure amount can be obtained even when the shooting distance changes. Next, the photometric circuit will be described. The photometric circuit (photometric means) includes a second photosensor Ph2 composed of Cds which is a photometric light receiving element, a resistor R5 connected in series with the second photosensor Ph2, and a second photosensor Ph2 and a resistor R5. And a transistor TR3 having a base connected to a connection point between the second photosensor Ph2 and the resistor R5. The low voltage obtained from the secondary side of the oscillation transformer T is rectified by the diode D2 and the capacitor Cs.
The voltage is applied to the second photosensor Ph3 composed of Cds. One end of the photo sensor Ph3 is connected to the base of the transistor TR3, and the collector of the transistor TR3 is connected to the solenoid LC. Therefore, when the main switches S1 and S2 are turned on in order to operate the strobe circuit, the photometric circuit can be operated in conjunction therewith. When the subject brightness is equal to or higher than the predetermined high brightness (when the brightness is equal to or higher than the predetermined brightness), the resistance value of the second photosensor Ph2 decreases, the base voltage of the transistor TR2 increases, and the transistor TR3 increases.
Is turned on, a current flows through the solenoid LC, and the aperture is switched to the small aperture state. Accordingly, the first photosensor Ph1 is shielded from light by the light-shielding portion 51b, so that the reflected light of the strobe does not shine, as if the main subject is at a long distance, the dimming operation is prohibited, and the strobe emits full light. . On the other hand, when the subject luminance is lower than the predetermined high luminance, the resistance value of the second photosensor Ph2 increases, the base voltage of the transistor TR3 decreases, and the transistor TR3 is turned off, so that current also flows through the solenoid LC. Instead, the aperture remains the large aperture, and the light shielding portion 51b is also retracted to the retracted position where the first photo sensor Ph1 is not shielded from light. Therefore, the dimming operation is performed by the dimmer. Also, the second photo sensor Ph sensor Ph
2 is composed of Cds, the response speed to the light intensity change is slow, and even if the strobe reflected light is directly incident, the solenoid LC does not operate and does not affect the dimming operation. Therefore, the subject is properly exposed by the dimming operation. It should be noted that the predetermined high brightness is defined as one more than the exposure amount determined by the aperture value of the taking lens, shutter speed, and film sensitivity when performing flash photography.
２2 EV means higher luminance. For example, if the exposure amount during daytime synchro photography is 10.6 EV, 11.6 EV
The luminance is equivalent to 12.6 EV. As described above, when a high-luminance subject is photographed in the flash photography state, the aperture is automatically switched to the small aperture state, so that there is no overexposure at high luminance, and the dimming by the dimming means is performed. Since the operation is also prohibited, it is possible to perform good daytime synchro photography. [Second Embodiment] Next, a second embodiment will be described using the strobe circuit of FIG. In the first embodiment, in a normal state in which no strobe is used, a projection (not shown) provided on the strobe switch lever 4 causes an arrow in FIG. 2 to resist the urging force of the urging member. To the end of the moving range in the opposite direction (the position of the small aperture).
In the embodiment of the present invention, such correction is not performed, the strobe is not used, and when the solenoid is not operated, the large aperture is selected by the biasing member when the solenoid is not operated. Regarding the mechanism, the first
Since the embodiment is the same as that of the first embodiment, the description thereof is omitted.
Also, the basic operation of the strobe circuit and the operation of the light control means are the same as in the first embodiment, and a description thereof will be omitted. In the first embodiment, the photometric circuit is activated when the strobe circuit is turned on. In the second embodiment, the release button 6 is turned on regardless of whether the strobe circuit is turned on. The photometry circuit is operated in the initial operation of the above. In the circuit diagram of FIG. 5, S3 is an initial operation of the release button 6, that is, a photometry start switch which is turned on within a moving range of the release button 6 in which the shutter is not released even when the release button 6 is pressed, and Ph2 is A second photosensor composed of Cds, R5 is a second photosensor Ph2
The resistor TR3 is connected in series with the second photosensor Ph.
The transistor LC whose base is connected to the connection point between the resistor 2 and the resistor R5, LC is a solenoid, and the second photo sensor Ph
2, a resistor R5 and a transistor TR3 constitute a photometric circuit (photometric means). When the release button 6 is pressed, the photometry start switch S is pressed.
When 3 is turned on, the photometric circuit (photometric means) can be operated. When the subject luminance is equal to or higher than the predetermined high luminance, the resistance value of the second photosensor Ph2 decreases, the base voltage of the transistor TR2 increases, and the transistor TR3 is turned on. Is switched to the small aperture state. In this case, even if the strobe can emit light, the first photosensor Ph1 is shielded from light by the light-shielding portion 51b, so that the reflected light from the strobe does not shine and the main subject is as if the main subject is at a long distance. The light control operation is prohibited and the strobe emits full light. On the other hand, when the subject luminance is lower than the predetermined high luminance, the resistance value of the second photosensor Ph2 increases, the base voltage of the transistor TR3 decreases, and the transistor TR3 is turned off, so that current also flows through the solenoid LC. The aperture is still large. In this case, if the strobe can emit light,
Since 1b is retracted to the retreat position where the first photosensor Ph1 is not shielded from light, the dimming operation is performed by the dimming unit. Also in this embodiment, the second
Since the photo sensor Ph2 is made of Cds, the response speed to the light intensity change is slow, and the solenoid LC does not operate even if the strobe reflected light is directly incident, which does not affect the dimming operation. Absent. Therefore, the subject is properly exposed by the dimming operation. As described above, when a high-luminance subject is photographed in the flash photography state, the aperture is automatically switched to the small aperture state, so that there is no overexposure at high luminance. Since the operation is also prohibited, it is possible to perform good daytime synchro photography. In the above embodiment, when the subject brightness is higher than a predetermined high brightness, the light control operation of the strobe device is prohibited by blocking the first photosensor Ph1 by the light blocking portion 51b. However, the present invention is not limited to this example. When the subject luminance is equal to or higher than a predetermined high luminance, for example, the current is prevented from flowing through the first photosensor Ph1, or the current is prevented from flowing through the entire dimming circuit. It may be configured so that the operation of the dimming circuit is not performed. According to the camera provided with the light control strobe according to the first aspect, even when a high-luminance subject is photographed in the strobe photographing state, overexposure does not occur, and good printing is achieved. You can get a photo.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of a film unit with a lens provided with a light control strobe. FIG. 2 is a perspective view of an aperture switching mechanism. FIG. 3 is a front view showing an aperture switching state by an aperture switching mechanism. FIG. 4 is a circuit diagram of a flash circuit provided with a photometric circuit. FIG. 5 is another circuit diagram of a strobe circuit provided with a photometric circuit. [Description of Signs] 1 Photographing lens 4 Strobe switch lever 51, 52 Aperture blade LC solenoid Ph2 Second photo sensor

Claims (1)

1. A first stop, a second stop having an opening diameter larger than the opening diameter of the first stop, photometric means for measuring the luminance of the object, and a photometric means for measuring the luminance of the object. Switching means for switching the aperture to a second aperture when darkness is detected;
A strobe device having light control means for receiving strobe reflected light from a subject by strobe light emission and stopping strobe light emission when the amount of received light reaches a predetermined amount of light received, and whether the strobe device emits light or not When the light emission switching means is in a state of performing strobe light emission,
A camera equipped with a strobe, wherein when the light meter detects that the light is brighter than a predetermined luminance, the light adjusting operation by the light adjusting means is prohibited.