JPH02256033A - Close-up and backlighted photographing apparatus for fixed focus type atomatic exposure camera - Google Patents

Abstract

PURPOSE: To obtain a bright and clear photograph whether it is proximity photographing, flash photographing or backlight photographing by performing further diaphragming a diaphragm adjusted by an arithmetic control circuit or the like based on incident light quantity obtained by photometry made by the photodetector of a photometry circuit built in a camera. CONSTITUTION: This device possesses a switch circuit provided with a switch SW forcedly making a flash turning circuit in a preparation state and a resistance R4 inserted in parallel with the photodetector CdS of the photometry circuit at the time of turning on the switch SW. Thus, by depressing the switch SW of a proximity and backlight photographing device, the combined resistance of the photodetector CdS and the resistance R4 of a device is made smaller than a resistance value which the photodetector CdS has by itself, so that the diaphragm is adjusted based on an incident light quantity value larger than the incident light quantity value obtained by the photometry made by the photodetector CdS. Thus, the bright and clear photograph is obtained in the proximity photographing, the flash photographing or the backlight photographing.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a close-up and backlight photography device for a fixed-focus automatic exposure camera, and more specifically, to a close-up and backlight photography device for a fixed-focus automatic exposure camera. The present invention relates to a close-up and backlight photographing device for a fixed focus automatic exposure camera having a variable aperture diaphragm and a flash tuning circuit.

(Prior Art) Fixed-focus automatic exposure cameras are widely used because they are easy to operate and are inexpensive.

Since the focal length of the lens is fixed in such a camera, the aperture is automatically adjusted to obtain the optimum exposure value to obtain bright and clear photographs.

For this reason, such a fixed-focus automatic exposure camera includes an aperture whose aperture changes based on the amount of light incident on the camera measured by a light receiving element and a flash tuning circuit.

(Problem to be Solved by the Invention) In such a fixed-focus automatic exposure camera, for example, an arithmetic control circuit provided in the camera body adjusts the aperture based on the amount of light incident on the camera, which is measured by a light-receiving element of a photometering circuit. When the amount of incident light is insufficient after adjusting to the optimum value, the arithmetic control circuit operates the flash tuning circuit to fire the strobe to compensate for the insufficient amount of light, making it possible to obtain bright and clear photographs.

However, with conventional fixed-focus auto-exposure cameras, when taking close-up shots where the subject is close to the focal length of the lens, the resulting photos may become unclear, or when using flash photography, the resulting photos may be overexposed. In backlight photography, the subject is often photographed as white, and in the case of backlight photography, the entire surface of the subject may be photographed as black.

Therefore, the purpose of the present invention is to provide close-up photography, flash photography,
Another object of the present invention is to provide a close-up and backlight photographing device for a fixed-focus automatic exposure camera that can obtain bright and clear photographs regardless of the type of backlight photography.

(Means for Solving the Problem) As a result of various studies to achieve the above object, the inventor has found that
When using a fixed-focus automatic exposure camera for close-up photography, flash photography, or backlight photography, an arithmetic control circuit adjusts the aperture based on the amount of incident light measured by the light receiving element of the camera's built-in photometry circuit. By further narrowing down the
It was discovered that clear photographs can be obtained, and the present invention was developed.

That is, the present invention provides a fixed-focus automatic exposure camera having an aperture whose aperture changes based on the amount of light incident on the camera measured by a light-receiving element of a photometry circuit and a flash tuning circuit. The device is characterized by comprising a switch circuit provided with a switch for forcibly bringing the device into a ready state, and a resistor inserted in parallel with the light receiving element of the photometric circuit when the switch is turned on. Fixed focus automatic exposure camera close-up and backlight photography equipment.

(Function) By pressing the switch of the close-up and backlight photographing device of the fixed-focus auto-exposure camera of the present invention, the combined resistance of the light receiving element built into the camera and the resistance of the said device is increased by the combined resistance of the light receiving element itself. Since the aperture is adjusted based on the value of the incident light amount that is smaller than the resistance value measured by the photodetector and larger than the value of the incident light amount measured by the photodetector, the aperture is narrowed down even more than the aperture that is based on the value of the incident light amount actually measured by the photodetector. As a result, the depth of the lens becomes deeper and the resolution of the lens improves, making it possible to obtain clearer photographs.

At this time, since the flash tuning circuit is also in a ready state, the strobe is activated to compensate for the insufficient amount of light, making it possible to obtain bright photographs with proper exposure.

(Example) The present invention will be explained in detail using the drawings.

FIG. 1 shows a block diagram of a circuit constituting a close-up and backlight photographing device of a fixed-focus automatic exposure camera according to the present invention.

The arithmetic control circuit adjusts the aperture to the optimum value based on the amount of light incident on the camera measured by the photometering circuit, and if the amount of light incident on the camera is insufficient, it activates the flash tuning circuit to turn on the strobe. Make it emit light.

In the camera of this embodiment, each of the photometry circuit and flash tuning circuit is provided with a photometry correction circuit and a flash tuning correction circuit.

An example of such a photometry correction circuit and a flash tuning correction circuit is shown in FIG.

The flash tuning correction circuit shown in FIG. 2 is composed of a first transistor r rt and resistors fl, , rt2, and resistors R, , f12 are connected to the base side and collector side of the transistor TR0, respectively. 11 terminal A of resistor R2 and transistor TR-.

Terminal B on the emitter side of the transistor TR3 is connected to a resistor R's-IL built in the camera body, and resistors R, , R4 are connected to the base side and collector side of the transistor TR3.
is connected, and the terminal C of the resistor R4 and the transistor TR
A terminal of a light receiving element CdS of a photometric circuit built into the camera body is connected to the terminal on the emitter side of No. 2.

The resistor R4 of the 811th circuit is connected in parallel to the light receiving element CdS and in series to the transistor TR2.

The resistors fl, , R2 connected to the Bayes terminals of the transistors TR, TR, in such a flash tuning correction circuit and photometry correction circuit are supplied with a voltage 2 via a switch SW. are applied simultaneously.

The resistors R, -, used in this correction circuit are connected with resistance values that match the characteristics of the transistors TR1-x, and the transistors TR1 and TR2 perform switching operations in the saturation region to control each correction circuit. (1/ra + l/rc, +s 1st~
When photographing a nearby subject under sunlight using the fixed-focus auto-exposure camera of this embodiment having the circuit shown in Figure 2, when the switch SW is pressed, the voltage VCc
The resistance r(,,R) is determined by taking into account the degree of change in the resistance value of the light receiving element CdS during flash photography, backlight photography, etc., and the ASA value of the film loaded in the camera.

Since this resistor R4 is connected in parallel with the light receiving element CdS, the combined resistance value R of the resistance value r4 of the resistor R4 and the resistance value rCd@ of the light receiving element CdS is expressed by the following formula. The resistance value r of CdS is smaller than Cd1l.

The flash tuning circuit that is currently in use also becomes ready.

In the photometric circuit, as mentioned above, the combined resistance value of the resistor R4 of the photometric correction circuit and the photodetector CdS is the photodetector Cd.
Since it is smaller than the resistance value of S itself, the amount of incident light transmitted from the photometry circuit to the arithmetic control circuit becomes larger than the actual value photometered by the light receiving element CdS.

For this reason, the arithmetic control circuit narrows down the aperture further than the aperture for the incident light amount value actually measured by the light receiving element CdS, so the depth of the lens becomes deeper and the resolution can be improved. Even if the subject is dark, you can get clear photos.

At that time, the aperture is narrowed down and the exposure is insufficient, so the strobe of the flash tuning circuit that is in the preparation state immediately fires to compensate for the insufficient amount of light.In such a situation, conventional fixed focus automatic exposure In some cases, the camera's flash tuning circuit does not work, resulting in the subject being photographed in black and blurry.

On the other hand, in the camera of this example, the flash tuning circuit is in a ready state and the strobe aperture is set to its maximum aperture, so the strobe fire causes overexposure and the subject becomes white. Phenomena that may be photographed may occur.

In this regard, in the camera of this embodiment, as described above, by pressing the switch SW, the aperture is narrowed down more than the aperture that corresponds to the actual amount of incident light, so the aperture must be set to match the ASA value of the film. and can obtain good photos.

Furthermore, during backlight photography, the amount of incident light measured by the light receiving element CdS is large, so the aperture is set to the minimum aperture.

In this way, the close-up and backlighting device of the fixed-focus auto-exposure camera of this embodiment can be used for close-up photography where the subject is close to the focal length of the lens, indoor flash photography, and backlight photography. Since the diaphragm can improve the resolution of the lens and provide appropriate exposure, it is possible to obtain bright and clear photographs.

In this embodiment, the resistor R4 of the photometry circuit is one fixed resistor, but the resistor R4 may be a variable resistor whose resistance value can be changed depending on the ASA value of the film, etc., and the resistor R4 is parallel to the resistor R4. A plurality of resistors may be provided and the resistor may be switched to a resistor having an appropriate resistance value depending on the ASA value of the film or the like.

In the embodiments described above, transistors are used as switching elements in each circuit, but a flash tuning circuit can be prepared by pressing the switch SW as shown in FIG. 3 without using the transistors. However, the resistor R4 may be connected in parallel with the light receiving element CdS.

(Effects of the Invention) According to the present invention, it is possible to perform close-up photography where the subject is close to the focal length of the lens, indoor flash photography, or backlight photography, which was difficult to capture with conventional fixed-focus automatic exposure cameras. Even when taking pictures, it is now possible to take bright and clear pictures, and it is now possible to take pictures with a fixed focus automatic exposure camera.
The i range can be expanded.

[Brief explanation of drawings]

FIG. 1 shows a block diagram of a circuit constituting a close-up and backlighting device for a fixed-focus automatic exposure camera according to the present invention;
1A is the flash tuning h11 positive circuit shown in No. 1174 and a! FIG. 3 shows a circuit diagram of the optical auxiliary IE circuit, and FIG. 3 shows a circuit diagram showing another embodiment. In Figure 1, TR,...first transistor, 'R3...second transistor, R+, R2, Ri, nq...resistance, CdS.
... Light receiving element, A, B... Terminal with flash tuning circuit, C, D...
・Terminal with photodetector CdS, SW... ・Switch, V((...voltage.

Claims (1)

[Claims] In a fixed-focus automatic exposure camera having a flash tuning circuit and an aperture whose aperture changes based on the amount of light incident on the camera measured by a light receiving element of a photometry circuit, a switch for forcibly putting the flash tuning circuit into a ready state. Close-up and backlight photography of a fixed-focus automatic exposure camera, characterized in that it is equipped with a switch circuit provided with a switch circuit, and a resistor inserted in parallel with a light receiving element of a photometric circuit when the switch is turned on. Device.