JPH0723772Y2 - Camera exposure calculator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICABILITY The present invention relates to an exposure calculation device for a camera, which can change a shutter speed and an aperture value determined by a program by an operation, and can also reset a change amount given by the operation. Regarding

2. Description of the Related Art Conventionally, in a camera equipped with a program exposure device for inputting brightness information and film sensitivity information of a subject and determining a shutter speed and an aperture value having a certain relationship based on the inputs, operation of an operation switch Thus, the shutter time and aperture value are changed, a reset switch is provided, and the change amount given by the operation switch is reset by operating this switch, and the shutter time and aperture value of the standard program are restored. JP-A-54-1
No. 38431 is disclosed.

Problems to be Solved by the Invention With the configuration disclosed in Japanese Patent Laid-Open No. 54-138431, when the shutter speed and aperture value determined by the reference program diagram are changed once by operating the operation switch. As long as the operation switch or the reset switch having the opposite action to the operation switch is not operated, the given change amount remains stored. Also, since it is often the case that the shooting based on the set change amount is performed only once, it is necessary to reset the change amount given by the operation of the operation switch at the next shooting. If not, the photo is against the photographer's intention. Furthermore, providing a reset switch in addition to the operation switch
Not only is this costly increased, but it is also not desirable in terms of reducing the size and weight of the camera.

Means for Solving the Problems The present invention automatically adjusts the change amount when it is appropriate to cancel the change amount set to solve the above problem, that is, when the lens is replaced. It is an object of the present invention to provide an exposure control device for a camera, which can reset the camera and does not perform an unnatural operation when the lens is not attached when the lens is replaced.

In order to achieve the above object, the present invention provides a shutter in a camera with interchangeable lenses, based on a predetermined program diagram shown on a graph showing a combination of brightness information of a subject and shutter speed and aperture value. Program calculating means for calculating the time and aperture value,
The operation means, the change amount setting means for setting the change amount for changing the shutter speed and the aperture value by a signal from the operation means, and the predetermined program corresponding to the output of the change amount setting means Changing means for changing from a diagram to a different diagram on the above graph, reset means for automatically resetting the setting change amount of the change amount setting means in response to lens exchange, and aperture when the lens is not attached The value is regarded as a constant aperture value, and is composed of a calculating means for calculating the shutter speed.

The action program calculation means calculates the shutter speed and the aperture value based on the brightness information and a predetermined program diagram. When the operating means is operated, the change amount setting means receives a signal from the operating means and sets the shutter speed and the change amount of the aperture value. The program diagram is changed to a diagram different from the predetermined program diagram based on the set change amount. When the lens is replaced after the change amount is set, the change amount is reset by the resetting means. When the lens is exchanged and the lens is not attached, the calculation is performed assuming that the aperture value is constant.

Embodiment FIG. 2 shows a configuration according to an embodiment of the present invention. MC is a microcomputer (hereinafter referred to as a microcomputer) that controls the entire camera, and (S1) is a switch for performing an exposure preparation operation. When the switch is turned on, the microcomputer (MC) is interrupted and the microcomputer (MC ) Start. (S2) is a release switch that starts the exposure control operation, (S _U ),
(S _D ) is a program shift switch for changing the shutter speed and aperture value determined in the program mode (hereinafter referred to as program shift). By turning this switch on, the program shift direction and shift amount can be changed. Can be set. (SM1) and (SM2) are exposure mode setting switches. Depending on the ON / OFF combination of these switches, you can set the aperture value and shutter speed manually by operating the manual mode (hereinafter M mode) and aperture value. Aperture priority mode (hereinafter A mode) that automatically determines the shutter speed, shutter priority mode (hereinafter S mode) that automatically determines the aperture value when shutter time is set, aperture value and shutter time It is possible to select four types of exposure modes, which are automatically determined program modes (hereinafter referred to as P modes). The program shift switches (S _U ) and (S _D ) and the exposure mode setting switches (SM1) and (SM2) are connected to the input port of the microcomputer (MC), and the above functions are implemented by the program of the microcomputer (MC). Has been realized. (IS) is an exposure information setting section that sets exposure information such as film sensitivity, (LM) is a metering section that measures the brightness of the subject, A / D converts the metering output, and outputs it as a digital value, (EX) Is an exposure control unit that controls the aperture and shutter in response to a signal from the microcomputer (MC), (D
S) is a display unit that receives a signal indicating photographing information from the microcomputer (MC) and decodes and displays the signal. (LN),
(FL) and (AC) are accessories that are attached to the camera body, and indicate interchangeable lenses, electronic flash devices, and other accessories, respectively. The interchangeable lens (LN) outputs lens information such as the maximum aperture value and the maximum aperture value and information to the bus line to confirm whether or not the lens is properly mounted. The electronic flash unit (FL) outputs various data including a charge completion signal indicating that the electronic flash unit has completed charging to the bus line. Other accessories (AC)
Is a data back that can control the exposure of the camera, a receiver for remote control shooting, etc.The information output from this accessory to the bus line includes the shutter speed and aperture value. Is performed. It should be noted that this information also includes information for confirming that the accessory controls the camera. (TR) is a transistor for supplying power to the photometry section (LM) and display section (DS), and the base is connected to the port of the microcomputer (MC) via a resistor. The bus line is a bus line common to the microcomputer (MC), the photometry unit (LM) and the display unit (DS), and is also connected to the accessory via a connector (not shown) on the camera body.

The operation of the circuit configured as described above will be described with reference to the flowchart showing the outline of the program of the microcomputer (MC) shown in FIG.

The microcomputer (MC) turns off the transistor (TR) and stops itself when the camera is not controlled to reduce current consumption (). When the switch (S1) is turned on to take a picture, an interrupt occurs and the microcomputer (MC) starts. Microcomputer (MC) outputs port
Set to low level (hereinafter “L”), which turns on the transistor (TR) (), metering unit (LM), display unit (DS)
The power is supplied to and the photometry is started. Next, set the timer built in the microcomputer (MC) to 10 seconds,
Start this (). This timer is used to keep the power supply for 10 seconds after the switch (S1) is turned off. Next, input the information signal from the information setting section (IS), check if there is any change in film sensitivity, etc., and if there is a change, change the film sensitivity value etc. stored in the microcomputer (MC) (). . Then, the states of the exposure mode selection switches (SM1) and (SM2) are input and the set exposure mode is stored (). Next, the information from the interchangeable lens (LN), electronic flash device (FL) and other accessories is taken into the microcomputer (MC) in order through the bus line (). Then check if the program is being shifted.

Here, the program shift will be described with reference to FIG. In FIG. 4, the horizontal axis represents shutter speed in apex display (TV), and the vertical axis represents aperture value in apex display (AV). The program diagram that serves as a reference is the program diagram that passes through the point P indicated by the solid line. This program diagram passes through the shutter speed (SS) = 1/2000 second, aperture value (F _NO ) = 32, and the apex (TV, AV) = (11,10) Is TV: AV = 3: 5, and when AV = 1 (F _NO = 1.4), only TV changes. Where Ev
(Exposure value) = 13 P in the standard program diagram
The (8,5) point is selected. Then, when the photographer is dissatisfied with the shutter speed or aperture value determined by the reference program diagram, the program shift change switch (S _U ) is turned on once, and P (8, 5) is changed to P ₁ (9 , 4). When it is turned on once more, P ₁ (9,4) moves to P ₂ (10,3). On the other hand, switch the program shift (S _D )
When turned ON, P (8,5) is P- ₁ (7,6), P- ₂ (6,7) ……
The program shifts. In the above description, the program shift change switch (S _U ) or (S _D )
The aperture value and the shutter time are changed by 1EV with respect to ON, but in the embodiment described later, the aperture value and the shutter time are changed with respect to ON of the switch (S _U ) or (S _D ). Each is changed by 1/2 EV.

The details of the program shift process are shown in FIG.

In FIG. 5, first, the states of the program shift switches (S _U ) and (S _D ) are checked (,), and when these switches (S _U ) and (S _D ) are turned OFF, , And the change amount (ΔP) of the program is changed to (ΔP + 1) and (ΔP−1) (,), respectively. Switch (S _U )
To confirm that and (S _D ) have been turned from OFF to ON, provide a flag that is set when the switch is turned OFF.
Make sure that the flag is set when the switch is turned on. Next, it is determined whether or not the condition for resetting the shift of the program is determined by. Then, in the following four cases, it is apparently determined that the photographer no longer intends to photograph by the shifted program, and the shift of the program is reset ().

(1) When the exposure mode is changed from P mode to another mode ().

(2) When the lens is replaced (when removed)
().

(3) When charging of the electronic flash device is completed ().

(4) When the camera is controlled by the accessory ().

These determinations are made using the information obtained in the processes of and. Besides the above four cases,
The program shift is reset when the power is turned off ().

After changing the program shift, input the brightness information from the photometric unit (LM) () and perform the exposure calculation (). The outline of the exposure calculation is shown in FIG. In FIG. 6, when the interchangeable lens (LN) is not attached, the subject light entrance aperture is regarded as a constant aperture value, and the shutter speed (TV) is calculated from the photometric value and film sensitivity at that time. When the interchangeable lens (LN) is attached and the camera is controlled by the accessory (AC), the shutter speed and aperture value signals are output from the accessory (,). When the electronic flash device is fully charged when the lens is attached and the camera is not controlled by the accessory (AC), calculation for flash photography is performed and the shutter speed and aperture value signals are output ( ,). In other cases than the above, when the exposure mode is the P mode, A mode, and S mode, the calculation of the corresponding mode is performed, the shutter speed and aperture value signals are output (to), and the M mode is also used. In the case of, a signal of the set shutter speed and aperture value is output (), and the calculation ends. The calculation () in the P mode will be described in detail with reference to FIG.

FIG. 7 is a flow chart for realizing the program diagram shown in FIG. First, subject brightness (BVO), aperture value (AVO), and film sensitivity (SV) during open metering
And EV exposure value (EV) from the equation EV = (BVO + AVO) + SV
From the maximum exposure control value of the camera (EV = 21 (TV = 11, AV = 10) in this embodiment), the current exposure value (E
Find the difference (ΔEV) from V) (). From this difference (ΔEV) and aperture value (AV), shutter speed (TV) distribution ratio (program inclination) = 5/8 and maximum aperture value (AV) = 10, the aperture value for the current exposure value (EV) Calculate (AV) ().
When the calculated aperture value (AV) is smaller than the aperture value (AV0) of the lens used, the aperture value (AV) is replaced with the aperture value (AV0) (,
), If not smaller, the aperture value is used as is (), and the shutter speed (TV) is calculated from the exposure value (EV) and aperture value (AV) (). The reference program diagram is determined by the above.

Next, the shift of the program thus determined will be described. First, the program shift amount (Δ
Put P) into the accumulator which is a register in the microcomputer (MC) (). It is determined whether or not the program shift amount is 0 (). When the program shift amount is 0, it means that the program shift has not been performed, and the calculation is ended. If it is not 0, the shift direction is first determined (). When the shift amount (ΔP) is positive, the shutter time (TV) is increased by 1 / 2EV (), and when the shifted shutter time (TV) exceeds the maximum speed (TV = 11), the shutter time (TV) is increased. Replace (TV) with the highest speed (TV = 11) (,), and use shutter speed (TV + 1/2) when it does not exceed. Then, the aperture value (AV) is calculated from the exposure value (EV) and the shutter speed (TV) (). When the aperture value (AV) is smaller than the maximum aperture value (AV0), the aperture value (AV) is replaced with the maximum aperture value (AV0) (,), and the shutter speed (TV) is calculated again (). If it is not small, use the actual aperture value (AV) and shutter speed (TV) (). Then, subtract 1 from the accumulator (ACC) () and return to.

On the other hand, when the program shift amount (ΔP) is negative, the shift direction is opposite, so 1/2 EV is subtracted from the shutter speed (TV) (). If the subtracted shutter speed (TV) is slower than the minimum speed (TV = -5), replace the shutter speed (TV) with the minimum speed (TV = -5) (,). The shutter speed (TV) is used as is (47), and the aperture value (AV) is calculated from the exposure value (EV) and shutter speed (TD) (). When the aperture value (AV) exceeds the maximum aperture value (AVmax), replace the aperture value (AD) with the maximum aperture value (AVmax) (,
) Calculate shutter time (TV) again (). If it does not exceed, use the aperture value (AV) and shutter speed (TV) as they are (). And accumulator (AC
Add 1 to C) and go back to 44. Accumulator (AC
The processing from to until the content of C) becomes 0 is repeated for the number of program shift amounts (ΔP), and the exposure calculation is completed.

Returning to FIG. 3, when the exposure calculation is completed, the result is output to the display unit (), and the aperture value (F _NO ) and shutter speed (SS) are displayed. Next, the release switch (S2)
If it is ON, the exposure is performed at the above aperture value (F _NO ) and shutter speed (SS) (,) After the exposure is completed, the following processing is performed again. If the switch (S1) is ON while the release switch (S2) is OFF, it returns to (,). When the switch (S1) is OFF, determine whether the timer set by exceeds 10 seconds (),
If not exceeded, the following processing is performed. At this time,
In order not to pass, the timer continues to count. After 10 seconds, the program shift is reset (), then the transistor (TR) is turned off, the power supply to each device is stopped, and the operation itself is stopped (). As a result, the power is retained for 10 seconds and the program shift is reset when the power is turned off.

FIG. 8 is a program diagram for explaining another embodiment of the program shift. In the program shift described above, when the shift switch (S _U ) or (S _D ) is turned on, the shutter speed (TV) and aperture value (AV) obtained by the reference program are shifted by a fixed value. However, in contrast, in the embodiment shown in FIG. 8, when the program shift switch (S _U ) or (S _D ) is turned on,
It is intended to change the inclination of the reference program. More specifically, the solid line in the figure is the same as the program diagram shown in FIG. 4 with the inclination (TV) :( AV) = 3: 5. In the program diagram (a), the inclination is (TV): (AV) =
1: 3, the slope of the program diagram (b) is (TV): (AV) = 1:
It is 1. Here, when the program shift switch (S _U ) is turned on, the solid line shifts the point q shifted to the program diagram of (a) to q1. When the switch (S _D ) is turned on, the solid line is shifted to the program diagram of (b) and the point q is shifted to q ₋₁ . The steps of changing this slope or the number of species may be increased, or even shifted to various different types of programs.

Although the embodiment according to the present invention has been described above, the present invention is not limited to this. For example, the exposure mode does not necessarily require four types (P, A, S, M modes), and at least the P mode may be provided, and the determination of the mode not provided in the flowchart at that time may be deleted. Further, the flash photographing determination may be performed by the camera inputting a signal indicating that the electronic flash device is mounted.

Effect of the Invention As described in detail above, according to the present invention, when the lens is replaced after the aperture value and the shutter speed determined by the program are changed by the operation, the above change is automatically canceled. In addition, the operation is simplified, and it is possible to eliminate a photograph inadvertently against the photographer's intention. Further, since it is not necessary to provide a reset switch for resetting the above changes, not only the cost can be reduced but also the camera can be reduced in size and weight.

Also, when the lens is replaced and the lens is not attached, the aperture value is regarded as a constant aperture value and the calculation is performed, so there is no malfunction or abnormal operation.
The display and release operate in the same way as in normal operation, and the camera operation can be checked with the lens removed.

[Brief description of drawings]

FIG. 1 is a configuration diagram corresponding to the scope of claims for utility model registration of the present invention. FIG. 2 is a circuit diagram showing an embodiment of the present invention.
FIG. 4 is a flow chart showing control by a microcomputer used in the present invention, FIG. 4 is a program diagram showing a first embodiment of program shift, FIG. 5 is a flow chart showing control for changing program shift, and FIG. Is a flow chart showing the control of the exposure calculation, FIG. 7 is a flow chart showing the exposure calculation in the program mode, and FIG. 8 is a program diagram showing the second embodiment of the program shift. Program calculation means (1) Operation means (2), (S _U ), ( _SD ) Change amount setting means (3) Program change means (4) Reset means (5)

Continuation of the front page (56) Reference JP 54-138431 (JP, A) JP 55-134821 (JP, A) JP 59-34520 (JP, A) JP 54-78127 (JP , A)

Claims (1)

[Scope of utility model registration request] 1. In a camera with interchangeable lenses, the shutter speed and aperture value are calculated based on a predetermined program diagram shown on a graph showing a combination of brightness information of a subject and shutter speed and aperture value. Corresponding to the output of the program calculation means for calculating, the operation means, the change amount setting means for setting the change amount for changing the shutter speed and the aperture value by the signal from the operation means, and the output of the change amount setting means. , A changing means for changing the predetermined program diagram to a different diagram on the graph, a resetting means for automatically resetting the setting change amount of the changing amount setting means in response to the lens exchange, and a lens An exposure calculation device for a camera, which has a calculation unit that calculates the shutter speed by assuming that the aperture value is a constant aperture value when not attached.