JPH0513291B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an improvement in an exposure control device for a shutter that also functions as an aperture, which performs daytime synchronization using a strobe light source. [Conventional technology] Conventionally, when shooting during the day, the brightness of the subject is metered and the aperture aperture is then used to take the photo. Also, at night, a strobe is used to take pictures with an aperture determined by the strobe's guide number and subject distance. However, during daytime synchronized shooting, two apertures are available, one determined by the subject brightness and the other determined by the subject distance, so you can compare the two apertures and use the smaller aperture for flash photography. The so-called small aperture priority control was used to control the shutter that also serves as an aperture. [Problems to be Solved by the Invention] In the conventional exposure control device as described above, during daytime synchronized shooting, if the two apertures, the aperture determined by the subject brightness and the aperture determined by the subject distance, match. For the main subject that is hit by the strobe light, the exposure determined by the aperture determined by the brightness of the subject and the exposure determined by the aperture determined by the distance to the subject are both appropriate exposures, so as a result, each appropriate exposure is added, so the exposure is doubled. This results in overexposure of 1EV. [Means for Solving the Problems] The present invention includes a shutter that also serves as an aperture, a photometer for detecting subject brightness, a subject distance detecting means for detecting subject distance, a strobe, and, during daytime synchronized photography, a photometer for detecting subject brightness. the first aperture aperture of the aperture shutter, which is set based on the subject brightness detected by the aperture shutter; an exposure control device that compares a second aperture aperture of a shutter that also serves as an aperture, and controls the strobe to emit light and close the shutter at the smaller aperture aperture; The aperture diameter and the second
The problem is solved by providing the exposure control device with a control means that causes the strobe to emit light when an aperture diameter one step smaller than the first aperture diameter is formed when the aperture diameters of the first aperture and aperture of the first aperture substantially match. It was done. [Embodiment] FIG. 2 is a block diagram showing the operation of the present invention. The photometry means 1 detects the brightness of the subject using a light receiving element and outputs brightness information to the control means 2. The information means 3 outputs information such as film sensitivity to the control means 2. The storage means 4 stores the shutter opening characteristics shown in the table above. The following table is a table of shutter times and strobe trigger signal generation timings stored in the storage means 4. This table is not derived from the Sekiho formula for giving appropriate exposure for parameters such as subject brightness, aperture, shutter time, subject distance guide number, and film sensitivity when using AE or strobe, but is based on actual results. The data obtained from the measured results regarding the ivy shutter.
It is a table. The control means 2 selects from the storage means 4 or performs selection calculations to determine the shutter time necessary to give proper exposure to the film based on the values from the photometry means 1 and the information means 3. As described above, the shutter time is temporarily stored in the control means 2, and when exposure control is performed later, the shutter section 5 is controlled using this stored value to take a picture. For this reason, although it is difficult for conventional mechanical artificial light emitting means to emit light within the shutter opening, this system allows setting of light emission at any aperture diameter within the aperture. That is, when using a strobe as auxiliary light, the ratio between the amount of natural light and the amount of auxiliary light can be set relatively arbitrarily, making it possible to take high-quality photographs. Although the above is divided into blocks for clarity of explanation, integrated circuits allow each block to be integrated into one IC.
The advantages of the present invention are particularly noticeable in microcomputers.

[Table] The following specific examples of the present invention will be described. This embodiment was implemented using a lens shutter using 135 film, and FIG. 3 shows a plan view of an embodiment of the shutter mechanism, and FIG. 4 shows a circuit diagram of the main parts of the embodiment. When using a strobe for photography, turn on the strobe power switch So to supply power to the strobe circuit 6, and charge the strobe capacitor 61 with a voltage boosted to approximately 300V.When charged, the resistor 62
Through this, the neon tube 63 is lit, and it is possible to know that the strobe light emission preparation is complete. switch here
Switch 3 in the information means 3 that opens and closes at the same time as So
1 is also turned ON, and the information of the strobe switch 31 is set in the microprocessor (hereinafter referred to as microcomputer) 8 which has both the control means 2 and the storage means 3. Next, the first stage of the two-stage release switch S ₁
When is pressed, power is supplied to the entire circuit, and the microcomputer 8 starts operating, first performing automatic focus detection (AF). The AF method of this embodiment is carried out by the distance measuring circuit 7, in which the infrared LED 71 emits light and the position detection element 72 receives the infrared light reflected from the subject to measure the distance. capacitor 73
When charging is almost completed, the infrared light emitting transistor 74 is made conductive to release the charge in the infrared light emitting capacitor 73 and the infrared LED 71 is turned on. The emitted infrared light is reflected by the subject and received by the position detection element 72;
consists of two light receiving elements, and the current varies depending on the amount of light received. This is amplified by AC amplifier circuits 75 and 76, and compared with the electrical signal of the distance switching distance by a comparison circuit 78 to obtain distance information. Distance information, which is the output signal of this comparator circuit 78, is input to the microcomputer 8, but the timing at which the microcomputer 8 receives this input signal is approximately after the infrared light is emitted.
In this embodiment, 100 μsec is optimal, and the distance information received at this timing is stored in the microcomputer 8. Next, the microcomputer 8 measures the subject brightness. The subject brightness measurement in this embodiment is carried out by the photometry means 1, and 11 is the CDS of the light receiving element. The operation of this photometric means 1 is controlled by the microcomputer 8 which controls the light receiving element 11.
The capacitor 12, which is a series circuit of an integrating capacitor 12 and The time during which the reference value is exceeded is measured from the time when the transistor 13 is turned off, and the brightness of the subject can be detected from this time. Here, the time (photometry time) T from when the transistor 13 is turned off until the reference value is reached is T=C Rcds·lnV _B −Vref/V _B. Here, _VB : power supply voltage Vref: reference voltage Rcds: resistance value of cds C: integral capacitor capacity. Furthermore, if _VB is determined by resistor division so that VB becomes Vref= _VB , then T=C・Rcds・ln(1−K), and the photometry time has no dependence on the power supply voltage.
It is determined only by the CDS resistance, capacitor capacity, and resistance division ratio. Since Rcds is determined by the amount of light received, the subject brightness can be determined by detecting the photometry time T. That is,
The relationship between the amount of light and the photometry time is stored in advance in the microcomputer 8, and the brightness of the subject is determined by selecting the stored value from the photometry time. The advantages of the photometry method described above are: (1) There is no need to specify the γ value of CDS. (2) The resistance value of CDS at a certain light intensity can be easily corrected by the resistance division ratio. (3) The circuit configuration is simple. (4) No dependence on power supply voltage. On the other hand, a drawback is that it is affected by variations in γ values, but this is negligible for photography. Here, the microcomputer 8 inputs information from the film sensitivity switches 32 and 33 in the information means 3. In this embodiment, film sensitivity information is read from a DX film container, and the film sensitivity information is automatically read every time the camera is loaded with a DX film container and the camera performs a photographing operation. In this example, the film has a film sensitivity of ISO 100,
Since it is limited to three types, 200 and 400, each film sensitivity can be selected by a microcomputer using a 2-bit signal. By the way, in response to the DX method code,

〔Effect of the invention〕

In the present invention, during daytime synchronized shooting,
If the two apertures, the aperture determined by the brightness of the subject and the aperture determined by the distance to the subject, match, the strobe will fire with an aperture one stop smaller than the aperture determined by the subject brightness, so the main subject will be overshot by the strobe light. This has the effect of ensuring proper exposure.

[Brief explanation of drawings]

1a and 1b show characteristic diagrams of the relationship between the shutter and the exposure amount, FIG. 2 is a basic block diagram of the present invention, FIG. 3 is a plan view of the shutter mechanism of the present invention, and FIG. 4 is a diagram showing the relationship between the shutter and the exposure amount. 1 shows a circuit diagram of main parts of an embodiment of the present invention. FIG. 5 is a flowchart showing the operating process of the microcomputer of the present invention, and FIG. 6 shows the relationship between shutter opening and light emission timing. DESCRIPTION OF SYMBOLS 1...Photometry means, 2...Control means, 3...Information means, 4...Storage means, 5...Shutter section, 6...
...Strobe circuit, 64...Transistor, 65...
... Thyristor, 7... Distance measuring circuit, 8... Microcomputer, 91, 92... Shutter blade, 93... Shutter blade lever, 98, 51... Shutter magnet.

Claims (1)

[Claims] 1. A shutter that also serves as an aperture, a photometer for detecting subject brightness, a subject distance detecting means for detecting subject distance, and a strobe. a first aperture aperture of the aperture-shutter, and a second aperture aperture of the aperture-shutter that is set based on a guide number of the strobe and a subject distance detected by the subject distance detection means. In comparison, in a camera having an exposure control device that controls the strobe to emit light and close the shutter at a smaller aperture aperture, the first aperture aperture and the second aperture aperture are different from each other. For flash photography, characterized in that the exposure control device is provided with a control means for causing the strobe to emit light when an aperture diameter one step smaller than the first aperture diameter is formed when the aperture diameter substantially matches the first aperture diameter. Exposure control device.