JPH02732Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device for an automatic exposure control camera.

Conventionally, the shutter speed is determined according to information about the brightness of the subject, or the aperture of the lens is automatically adjusted according to information about the shutter speed set according to manual settings from the outside and information about the subject brightness. An automatic exposure camera has been proposed that is configured to automatically control shutter speed in accordance with information on an adjusted aperture value and information on subject brightness. With such automatic exposure cameras, if the aperture is set to the maximum aperture diameter or the minimum aperture diameter and the proper exposure still cannot be obtained, the preset shutter speed is automatically corrected to a value suitable for the proper exposure. Although very effective, it has been difficult to display the corrected shutter speed value. The present invention allows the minimum aperture limit to be arbitrarily preset in a program exposure control camera, and even when the aperture is controlled to the preset aperture value, the shutter speed is reset so as to obtain appropriate exposure at the preset aperture value. It is possible,
Another object of the present invention is to provide a camera that can display the reset shutter speed before the aperture control operation starts even when the shutter speed is reset.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of an example of a circuit according to the present invention. Reference numeral 1 denotes a photometry circuit that receives light from a subject passing through a photographic lens and generates a photometry output according to the brightness of the subject. A first circuit 2 generates a first signal corresponding to a shutter speed determined according to the photometric output from the photometric circuit 1 or a shutter speed determined according to manual setting from the outside. 3 is an aperture control device that automatically adjusts the aperture according to the first signal from the first circuit 2; Reference numeral 4 denotes a shutter control device that automatically controls the shutter speed in accordance with information on the aperture adjusted by the aperture control device 3 and information on subject brightness. The above two pieces of information applied to the shutter control device 4 can be extracted from the photometric output of the photometric circuit 1. A second circuit 5 generates a second signal corresponding to the shutter speed determined according to information on the controllable limit aperture diameter and subject brightness. Reference numeral 6 denotes a display device for displaying the controlled shutter speed, which can be displayed by a meter or by light emission.
7 is a comparison circuit that changes its state depending on the magnitude of the first signal and the second signal. Reference numeral 8 denotes a selection circuit that selectively applies the first signal or the second signal to the display device depending on the state of the comparison circuit.

In the initial stage of operation, the photometry circuit 1 performs photometry with the aperture fully open, and this photometry output is applied to the first circuit 2. The first circuit 2 generates a first signal corresponding to the shutter speed determined according to the photometric output or the shutter speed determined according to the manual setting from the outside, and sends this signal to the comparator circuit 7 as one input. Apply. On the other hand, the second circuit 5 generates a second signal corresponding to the shutter speed determined according to information on the controllable limit aperture diameter and subject brightness, and applies this to the comparison circuit 7 as the other input. do.

In the next step by pressing the shutter button, the diaphragm control device 3 automatically adjusts the diaphragm in response to the first signal. At this time, if there is no aperture value to be adjusted because the subject is too bright or too dark, the aperture control device 3 sets the aperture value in advance using the maximum aperture diameter, minimum aperture diameter, or aperture ring. Adjust to the preset aperture diameter. When this stage is completed, the shutter control device 4 automatically controls the shutter speed in accordance with the adjusted aperture value. The shutter speed controlled at this time corresponds to the second signal and is naturally different from the shutter speed corresponding to the first signal.

Therefore, the comparator circuit takes the first signal and the second signal as input, changes its state according to the values thereof, and when the shutter speed controlled by the shutter control device 4 corresponds to the first signal, A first signal is applied to the display device 6 via the selection circuit, and this
, a second signal is applied to the display device 6 via the selection circuit 8.

In this way, the display device always displays the shutter speed that is actually being controlled.

Further, the first signal generated by the first circuit 2 is
It includes a program signal corresponding to a shutter speed preprogrammed according to the subject brightness or a manual signal corresponding to a shutter speed manually set from the outside. In addition, the second signal generated by the second circuit 5 is a first correction signal corresponding to the shutter speed determined by the subject brightness when the aperture is at maximum aperture, and a first correction signal corresponding to the shutter speed determined by the subject brightness when the aperture is at its maximum aperture diameter or a preset aperture. a second correction signal responsive to a shutter speed determined by the subject brightness when the shutter speed is set.

Next, embodiments of the present invention will be described in more detail. 2a to 2c show the mechanical parts of the diaphragm control device and shutter control device in FIG. 1, FIGS. 3a and 3b show a shutter speed programming method, and FIG. 4 is a block diagram of the shutter speed control device shown in FIG. FIG. 2 is a circuit diagram showing a specific circuit configuration. Figure 5 a, b
2 is a diagram showing a display form of an indicator indicating shutter speed. FIG.

First, we will explain the mechanism. In FIG. 2a, when the shutter button (not shown) is pressed, the locking claws 12 move counterclockwise around the rotating shaft 133 against the spring 144 as the shutter buttons 11a and 1b move downward. The retaining claws 16 each rotate counterclockwise about the rotating shaft 17 against the spring 18. Then, the engagement between the claw portion 12a of the locking claw 12 and the rising portion 13a of the aperture operating lever 13 is released. The aperture operating lever 13 begins to rotate clockwise around the rotating shaft 20 together with the aperture lever 14 due to the spring force of a spring 15 fixed to the aperture lever 14 on the lens side. Open Switch S ₁ at its initial stage. When lever 13 rotates, pin 1
3c causes the intermediate lever 21 to rotate counterclockwise. The rotation is transmitted to the sector lever 23 via the intermediate shaft 22 (transferring to FIG. 2b). A part of the sector lever 23 is a gear 23a, and its rotation is caused by a gear 26 meshing with the gear 23a.
The speed is increased by the gear 28 meshing with the gears 27, 27 integral with the gears 27 and 26, and is transmitted to the ratchet wheel 29. On the other hand, when the locking pawl 16 is rotated as described above by pressing the shutter button, the locking portion 16a and the lever 51 are disengaged (as shown in FIG. 2c, the lever 51 is rotated around the shaft 52 by the force of the spring 53 The lever 51 starts to rotate counterclockwise. A part of the lever 51 is a gear 51b and is meshed with the gear 55. The gear 55 and the gears 56, 57, and flywheel 58 that are integral with it act as a delay mechanism. In the initial stage of the operation of the lever 51, the pin 56a set on the gear 56 is retracted clockwise, so that the lever 59 is rotated around the shaft 60 by the force of the spring 61. Then, the hold lever 63 rotates clockwise around the shaft 64 due to the force of the spring 65, releasing the lever 30 that had been pressed against the electromagnet Mg.However, as will be described later, the shutter button is not pressed. In the initial stage of , the power switch S _M is turned on and the electromagnet Mg ₁ is energized, so it is attracted to the electromagnet Mg ₁ and the lever 30 does not move.

When the aperture lever 14 on the lens side is moved downward by the force of the spring 15, the aperture of the lens is narrowed down from wide open to small aperture by a known mechanism. Due to the activation of the circuit, the electromagnet Mg ₁ is demagnetized and the iron piece 34 moves away from the electromagnet Mg ₁ , so that the lever 30
The spring 32 rotates counterclockwise, and its rising portion 30a enters and locks the ratchet pawl of the ratchet wheel 29. (Moving to FIG. 2a) When the lever 51 rotates further counterclockwise, it comes into contact with a portion 101a of the lever 101 near the end of its movement, and the lever 101 moves around the shaft 102 against the spring 103. and rotate clockwise to disengage the lever 104. Then, the lever 104 is rotated clockwise by the action of the spring 105, but at the initial stage, the pin 104a opens the switch _S2 . When the lever 104 further rotates, it pushes up a pin 106 fixed to a mirror holder (not shown) and the mirror rotates upward about a rotation axis 107. As the lever 104 rotates, the pin 104
b, the lever 108 rotates counterclockwise about the shaft 109 against the spring 110, and the lever 1
At the end of the rotation of 04, release lever 1 of the shutter
Press 11 to release the shutter.

When the predetermined exposure time has ended and the trailing curtain of the shutter has finished running, the signal lever 112 of the shutter moves downwards, so that the lever 115 is moved around the axis 116 against the spring 117 via the intermediate lever 113. and then rotated clockwise. Then lever 11
5 is disengaged from the lever 118, and the lever 119 is rotated clockwise about the shaft 120 by the force of the spring 121. Since a portion 119a of the lever 119 and a pin 118a fixed to the lever 118 are engaged with each other, the lever 118 rotates counterclockwise at the same time. At the initial stage of rotation of the lever 119, one end 119b of the lever 119 comes into contact with the lever 63, and is rotated counterclockwise to disengage the engagement between the rising portion 30a of the lever 30 and the ratchet wheel 29. When the levers 118 and 119 further rotate, the pin 118b fixed to the lever 118 comes into contact with the levers 104 and 13, and engages with both levers and the lever 13 21, 22, 23, 26, 27,
The series of systems 28 and 29 are returned to the positions shown. Therefore, the pin 106 is returned by a spring (not shown), so that the mirror is lowered, and the lever 14 is returned to its original position, returning the diaphragm to the open position.

When one photographing operation is completed and the upper lever is operated, the pin 122 will first move clockwise, the lever 51 will return to the position shown, and then the pin 123 will move clockwise. Move to lever 1
19 and 118 return to the positions shown.

Next, I will explain the program.

There are two possible programming systems for cameras with interchangeable lenses, such as single-lens reflex cameras, depending on how the difference between the maximum aperture diameter and the minimum aperture diameter of each lens is processed. Figure 3 shows typical examples of this for a lens with an open aperture diameter of F1.4 and a minimum aperture diameter of F16 (hereinafter referred to as lens A) and a lens with an open aperture diameter of F4 and minimum aperture diameter of F32 (hereinafter referred to as lens B). a and b. This program diagram is divided into three parts. As Fv increases, there is a part where only the shutter speed changes while the aperture remains at its open aperture diameter (hereinafter referred to as the x part), a part where both the aperture value and shutter speed change (hereinafter referred to as the y part), and the aperture remains at its minimum aperture diameter. There are three parts in which only the shutter speed changes (hereinafter referred to as the z part).

In the method shown in Fig. 3a, the above-mentioned lens A and lens B are
However, in the method shown in FIG. 3B, the y part of the lens B is the y part of the lens A translated in parallel. Below, we will try to derive the relational expression for the y part for each. For the sake of simplicity, the APEX expressions Av, Tv, Ev, Bv, and Sv are used in the relational expressions. From a simple consideration, the formula for the y part in Figure 3a is Tv = 0.75Av + 3.25 = 0.75 (Av - Av ⁰ ) + 0.75Av ⁰ + 3.25 ... (1) where, Av ₀ : Av of the lens open aperture diameter value 3rd
The y part in Figure b is Tv=0.5(Av- _Av0 )+6...(2). From this, the general formula for the y part is Tv = α (Av - Av ₀ ) + βAv ₀ + γ ...(3) where α, β, and γ are constants In the method shown in Figure 3 a, β = α The method shown in Figure 3 b Then, β=0. Here, the variable of aperture value is not Av but (Av−Av ₀ )
The reason for this is that this method is easier to handle when using the TTL photometry method.

Next, by introducing the formula for proper exposure for APEX display, Av+Tv=Bv+Sv, and transforming equation (3), we get Tv=α(Bv+Sv−Tv−Av ₀ )+βAv ₀ +γ Tv=α/1+α(Bv+Sv−Av ₀ )+1 /1+α(βAv ₀
+γ)...(4) The meaning of equation (4) is that it is on the straight line of the y part of the program a or b in Figure 3 and is appropriate for the given subject brightness, film sensitivity, and lens aperture. This is a formula that calculates the shutter speed that suits the exposure conditions.

Next, the circuit portion and operation will be explained.

In FIG. 4, in the program mode, terminal 201 is selected for _S2 , and the aperture ring of the lens is set to the minimum aperture (F16 for lens A, F32 for lens B). When the shutter button is pressed, the power switch S _M is turned on in the first step, and current is supplied to the entire circuit system from the power supply battery E1. The photodiode PD receives the light that has passed through the lens and the aperture and generates a photocurrent proportional to its intensity. This photocurrent is then logarithmically compressed by the amplifier OP1 and the diode D1. Constant current source CC1 and diode
_D2 is for compensating the temperature characteristics of the diode D1.
At this stage, the levers 12 and 16 have not moved yet, so the lens aperture lever 14 is set to lever 1.
3, the aperture of the lens is opened (the state shown in FIG. 2a). Therefore, the light incident on the photodiode PD is obtained by subtracting information about the aperture diameter of the lens from the object light, and the value obtained by logarithmically compressing it becomes (Bv - Av ₀ ) in APEX expression. The power of amplifier OP1 is supplied with film sensitivity information by variable constant voltage circuit E2.
Since a voltage corresponding to Sv is applied, the voltage V _A at the output terminal A point of the amplifier OP1 is V _A = (Bv + Sv - Av ₀ ) (5). This A point voltage is divided by resistors _R1 and _R2 . The resistance ratio of R ₁ and R ₂ is set to be α/1 + α in equation (4), so the resistance ratio of R ₁ and R ₂
The voltage at the connection point is α/1+α(Bv+Sv−Av ₀ ). This voltage is then applied to the amplifier OP2 via the switch S1, where information of 1/1 + α (βAv ₀ + γ) is added to this voltage by the constant current source CC2 and the variable resistor _R3 , and as a result, the amplifier The voltage V _B at the output terminal B point of OP2 is V _B =α/1+α(Bv+Sv−Av ₀ )+1/1+α(βAv ₀ +γ) (6), which corresponds to Tv according to equation (4). In the case of the program shown in Figure 3a, it is necessary to configure _R3 so that it changes depending on the aperture diameter of the lens, but in the program shown in Figure 3b, β=0.
R ₃ can be a fixed resistance equivalent to γ. one hand amplifier
The output voltage of OP1, that is, the voltage at point A, is the amplifier OP.
3 input terminal. Here constant current source
The aperture value set on the aperture ring by CC3 and variable resistor _R4 , which changes in conjunction with the lens aperture device.
Information of ((Av)preset−Av ₀ ) is subtracted from the APEX display. In this case, the aperture ring is set to the minimum aperture diameter, that is, Avmin, so the amplifier
The voltage V _C at the output terminal C point of OP3 is (Bv + Sv - Av ₀ ) - (Avmin - Av ⁰ ) = Bv + Sv - Avmin (7).

Comparing equations (5), (6), and (7) with the appropriate exposure equation for APEX display, Av+Tv=Bv+Sv, that is, Tv=Bv+Sv−Av, we find the following. That is, the A-point voltage V _A first correction signal indicates the Tv value that meets the conditions for proper exposure at the open aperture diameter, that is, the Tv value (Tv)a of the x section of the program diagram,
The B point voltage V _B (program signal) indicates the Tv value (Tv)b of the y part of the program diagram, and the C point voltage V _C (second correction signal) indicates the conditions for proper exposure at the minimum aperture diameter. Appropriate Tv value, i.e. z of the program diagram
The Tv value (Tv)c of the part is shown. The voltage V _A is further
Voltage follower F2 which is an analog switch of
and converter CP1, via switch S2.
At CP3, the voltage V _B is connected to the first analog switch voltage follower F1 and the comparator CP1,
At CP2, voltage V _C is applied to a third analog switch, voltage follower F3, and comparator CP2. These voltage followers F1,
F2 and F3 each have an enable terminal (control terminal), and when the enable terminal is at H level, the input voltage is output as is to the output terminal, and when the enable terminal is at L level, the output voltage is undefined.
It has a characteristic that the output impedance is infinite. Now, if V _B > V _A , (Tv)b > (Tv)a, but in this state, if you follow the y part of the program curve, the aperture value will be larger than the aperture of the lens. Therefore, control is inevitably performed according to the x part of the program curve. At this time, the output of converter CP1 is H
Since V _C is smaller than V _A , the output of comparator CP2 becomes L level. Therefore, the enable terminal of voltage follower F1 is set to L level by the output of NOR gate G, the enable terminal of F2 is set to H level, and the enable terminal of F3 is set to L level. Therefore, voltage V _A is applied to meter M via F2.

Next, when V _A > V _B > V _C , control follows the y part of the program curve, but at this time the output of comparator CP1 goes to L level and the output of comparator CP2 goes to L level. Therefore, the enable terminals of the voltage follower F1 are set to H level, F2 to L level, and F3 to L level.
Therefore, voltage V _B is applied to meter M via F1.

When V _A > V _C > V _B , the y part of the program curve is narrowed down more than the minimum aperture diameter, so control follows the z part, but in this case, comparator CP1 is L level,
The comparator CP2 outputs an H level, and the enable terminals of the voltage follower F1 go to an L level, F2 goes to an L level, and F3 goes to an H level. Therefore, a voltage V _C is applied to the meter M via the voltage follower F3.

As can be seen from the above, when the exposure control follows the x part of the program diagram, the voltage V _A is the voltage, when it follows the y part the voltage V _B , and when the exposure control follows the z part the voltage
V _C is applied to meter M, and the fifth point appears on the meter pointer.
By arranging the shutter speed scales to face each other as shown in Figure A, it is possible to always display the correct Tv value at which control is scheduled. Note that this display does not have to be based on a meter, but may be one in which a light emitting diode LED and a shutter speed scale are placed opposite each other as shown in FIG. 5b.

Next, if you press the shutter button further, the lever 1 mentioned above will be activated.
2 and 16 are released and the aperture of the lens is narrowed down by operating the lever 14, but before that the switch S1 is opened and the voltage at the connection point between the resistors _R1 and _R2 is stored in the capacitor C1 and the voltage is increased. V _B is fixed.
As the aperture is narrowed down over time, the amount of light incident on the photodiode PD becomes the value obtained by subtracting the information about the actual aperture at each point in time from the subject brightness, so the output voltage V _A of amplifier OP1 is ( Bv - Sv - Av), which represents the Tv value suitable for the appropriate exposure conditions corresponding to the aperture information at the time. Voltage V _A and stored voltage V _B are compared by comparator CP1, and when V _A and V _B match, the output of comparator CP1 becomes H level.
Therefore, the current flowing through the electromagnet Mg1 is cut off, and the tip 30a of the lever 30 enters the pawl of the ratchet wheel 29, fixing the narrowing lever 14, thereby stopping the narrowing operation. Next, when the lever 104 rotates and switch S2 opens, the voltage
V _A is stored in capacitor C2. This stored voltage V _A becomes one input of comparator CP3. When the mirror rises and the shutter is released by the lever 108, the trigger switch S4 opens when the front curtain of the shutter begins to run, and the amplifier OP opens.
4. A time logarithmic conversion circuit consisting of a constant voltage circuit E3, a capacitor C3, diodes D3 and D4, a resistor R5, and a constant current source CC4 starts operating. This circuit will output a voltage according to the Tv value of the exposure time after the shutter front curtain starts running.
When this Tv value matches the stored voltage V _A , the comparator CP3 operates, the electromagnet Mg2 is demagnetized, and the trailing curtain starts running.

Next, when the switch S3 selects the terminal 202, the shutter speed priority mode is entered. At this time,
The constant current source CC5 and the resistor R6, which is variable in conjunction with the shutter speed setting operation from the outside, generate an output voltage V _D at point α that provides the Tv value Tv,m of the manual shutter speed. This is then applied to comparators CP1 and CP2. Therefore the voltage
This means that V _D and the voltage V _B in the program mode described above have been replaced.

Now, when pressing the shutter button in the first step, V _D
>V _A > V _C , the aperture must be controlled to be larger than the open aperture diameter, so the shutter speed will inevitably be corrected from the manual speed setting. At this time, the output of comparator CP1 becomes H level, and the output of comparator CP2 becomes L level.
level, so the voltage V _A is applied to the meter M via the voltage follower F2. Then, the appropriate shutter speed when the aperture is at its open aperture diameter is displayed.

Next, when V _A > V _D > V _C , the shutter speed is controlled to the manually set value because the aperture is within the controllable range. At this time, comparators CP1 and CP2
The outputs of both are at the L level, and voltage V _B is applied to the meter M via the haltage follower F1. Therefore, the manually set shutter speed is displayed.

If V _A > V _C V _D , the aperture can only be narrowed down to the minimum aperture diameter, and the shutter speed will inevitably be corrected from the manually set value. In this case, the output of comparator CP1 becomes L level, and the output of comparator CP2 becomes H level, so meter M has voltage follower F3.
A voltage V _C is applied through. Therefore, the appropriate shutter speed when the aperture is at its minimum aperture diameter is displayed.

Thereafter, if the shutter button is further pressed, the exposure time will be controlled in the same manner as described above.

From the above, it can be seen that even in the shutter speed priority mode, the meter M displays the shutter speed that is actually controlled according to the aperture conditions.

Next, when the switch S3 selects the terminal 202, the aperture priority mode is set. Voltage V _B is then forced to the ground level. Resistor R4 introduces the information of the manually set aperture preset value ((Av) _preset −Av0, so the value of voltage V _C is Bv + Sv −
(Av) becomes _preset and indicates a Tv value suitable for proper exposure for the set aperture value. One side voltage
Since V _B is smaller than voltage V _C as described above, V _C is applied to meter M by the operation described above. During control, the output of CP1 always remains at the L level, so the aperture is not locked until it reaches the value set by the lens preset ring. When the aperture reaches the set value, the voltage is increased as described above.
The shutter is controlled by V _A.

Note that each mode can also be displayed using a light emitting element or the like in response to switching of the switch S3.

In the embodiments described above, if you accidentally set the aperture ring to a value other than the minimum aperture diameter in program mode or shutter priority mode,
It becomes impossible to control the aperture smaller than the set aperture diameter. At that time, control is performed as if the aperture value set by the aperture ring was the minimum aperture diameter, but in that case, the aperture diameter set by the resistor R4 is also controlled.
By introducing this into the circuit, it is possible to display the correctly controlled shutter speed.

Furthermore, since the voltage followers F1, 2, and 3 act as analog switches, it is obvious that they may be replaced with transistors or FETs.

In addition, in the embodiment described above, the elements PD1, OP
2, OP2, E2, D1, D2, R1, R1~R
3. CC2 is a first means for generating a first shutter speed signal, element MG1 and a mechanism for controlling the diaphragm shown in FIG.
2, S4, C2, C3, CP3, MG2, OP4,
D3, D4, R5, E3 are the shutter control device,
Element M is the display means, elements PD1, OP1, E2,
The elements PD1, OP1, E2, D1, D are used as a second means for obtaining the second shutter speed signal.
2, OP3, and R4 are the third means for obtaining the third shutter speed signal, elements CP1 and CP2 are the discriminating means that outputs the discriminating signal, and elements G, F1 to F3 apply each shutter speed signal to the display means. Each corresponds to the fourth means.

As detailed above, according to the present invention, in a program exposure control camera, it is possible to automatically obtain an aperture value that provides proper exposure only between the aperture value arbitrarily preset by external operation and the maximum aperture value. . In other words, the photographer can arbitrarily change the minimum aperture side limit of the range in which the aperture is controlled by program exposure control by external operation. Therefore, program photography can be performed in consideration of the aperture value when photographing, which is extremely effective for photographing.

Furthermore, in the present invention, even when the aperture is controlled to a preset aperture value by external operation as described above, the shutter speed is reset so as to obtain proper exposure at the aperture value, so the aperture can be set arbitrarily. Proper exposure can always be obtained even when reaching the minimum aperture limit.

Further, the present invention allows the shutter speed to be actually controlled to be displayed in advance in the camera described above even when the aperture reaches its control limit such as the open aperture value or the preset aperture value.

Furthermore, whether the aperture is controlled between the open aperture value and a preset aperture value, or when it is controlled to a control limit such as the open aperture value or a preset aperture value, the shutter can be controlled by the same display device. Since the speed can be displayed, there is no troublesome display and it is easy to use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of an embodiment of the display device for an automatic exposure control camera according to the present invention, and FIGS. 2a, 2b, and 2c are the aperture control device shown in FIG. 3 and a part of the mechanism of the shutter control device 4, FIGS. 3a and 3b are program diagrams showing the shutter speed program, and FIG. 4 is a concrete block diagram in place of the block diagram of FIG. 1. 5 is a circuit diagram showing the circuit configuration, and FIGS. 5a and 5b are diagrams showing the display form of an indicator showing the shutter speed. Explanation of signs of main components, First circuit...2, Second circuit...5, Comparison circuit...7, Selection circuit...
8.

Claims (1)

[Claims for Utility Model Registration] A first shutter speed signal relating to a shutter speed to be controlled only by electrical calculation according to subject brightness information obtained from light passing through an open aperture and a predetermined program. means, an aperture value setting means capable of presetting an arbitrary aperture value between the maximum aperture value of the lens and an aperture value corresponding to the minimum controllable aperture diameter by external operation; and a first shutter speed signal. Accordingly, when the aperture value determined to obtain proper exposure is between the open aperture value and the aperture value preset by the aperture value setting means, the aperture value is determined in accordance with the first shutter speed signal. While controlling the aperture to the aperture value, if the aperture value determined according to the first shutter speed signal exceeds the aperture value, the aperture value is controlled to the aperture value;
and an aperture control device that controls the aperture to the preset aperture value when the aperture value determined according to the first shutter speed signal exceeds the preset aperture value; a shutter control device that automatically controls the shutter speed so as to obtain proper exposure; a single display means for displaying the shutter speed; and a shutter control device that automatically controls the shutter speed to obtain the appropriate exposure; a second means for obtaining a second shutter speed signal related to a shutter speed for obtaining proper exposure based on a value, by electrical calculation alone; and object brightness information obtained from a signal related to the preset aperture value and light passing through an open aperture. a third means for obtaining, by electrical calculation alone, a third shutter speed signal relating to a shutter speed for obtaining proper exposure at the preset aperture value based on the preset aperture value; and an aperture determined by the first shutter speed signal. determining means for determining whether the aperture value exceeds the open aperture value or the preset aperture value and outputting a determination signal; and an aperture value determined by the first shutter speed signal according to the output of the determining means. When the aperture value is between the maximum aperture value and the preset aperture value, the first shutter speed signal is transmitted, and when the aperture value exceeds the maximum aperture value, the second shutter speed signal is transmitted, and the aperture value is the preset aperture value. and fourth means for applying a third shutter speed signal to the display means before the diaphragm control operation starts when the shutter speed exceeds the shutter speed signal, and the display means displays a shutter speed signal related to any one of the three shutter speed signals. An automatic exposure control camera that can control program exposure and displays speed.