JPS583525B2 - The most powerful reflex camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single-lens reflex camera that performs TTL photometry and controls the aperture of a photographic lens attached to the camera to perform automatic exposure control.

The aperture of the photographic lens is preset to the minimum aperture, and at each moment in the process of the aperture presetting member on the camera body sequentially narrowing down the aperture from the open state, TTL photometry is performed on the photographic light ray that passes through the changing aperture. When the diaphragm is narrowed down to the appropriate aperture, the aperture instant automatic determination type single-lens reflex camera stops the diaphragm operation by the aperture presetting member and automatically determines the appropriate aperture aperture.
This is publicly known from Japanese Patent Application Laid-Open No. 48-3929 filed by the present applicant.

This type of camera has the excellent feature that already commercially available interchangeable lenses can be used as they are as aperture EE lenses.

However, how to perform TTL photometry in this type of single-lens reflex camera with instantaneous automatic aperture determination is an important issue when putting this type of camera into practical use.

That is, in the conventional method, a photometric element for performing TTL photometry is placed in the viewfinder optical path or in the photographing optical path.
After the aperture is determined, the photometric element is retracted out of the photographing optical path, and then exposure is performed.

The former requires that the movable mirror is moved out of the photographing optical path after the aperture is determined, and then exposure is started, while the latter requires that the photometric element is moved out of the photographic optical path after the aperture is determined. , and then exposure must be started, and in either case, the operation of moving the movable mirror or the photometric element is performed between the determination of the aperture and the start of exposure.

This has the disadvantage that it is not possible to determine the aperture based on the subject's rays just before the start of exposure, and in the former case, if the photographer is wearing glasses or is using a self-timer, the viewfinder must be closed. There is a drawback that light rays other than the shooting light that enter through the eye enter the photometric element, causing errors in exposure. A driving member for moving the photometric element out of the photographing optical path in connection with the operation, and a drive member for returning the photometric element to the photographing optical path after the exposure is completed or when the release operation is performed and the release operation is canceled immediately before the start of exposure. This method requires a return member, which has the drawback of complicating the mechanism of the camera body.

The present invention does not require the movement of the photometric element, and can prevent the influence of light entering from the viewfinder eyepiece on the exposure.Furthermore, the present invention prevents the bounce of the aperture immediately after the aperture is determined, and the reflection characteristics of the film used. To provide a single-lens reflex camera with instantaneous automatic aperture determination, which enables stable exposure control at all times regardless of the situation, and which enables a series of photographing operations and return operations to be achieved rationally and reliably. The purpose is to

Therefore, in the present invention, the photometric element in the photometric circuit detects the subject light that passes through the photographic lens and its aperture and is reflected on the surface of the shutter front curtain facing the photographic lens, which has certain reflection characteristics. It is fixed in a position within the camera body that does not obstruct the photographic optical path so that the movable mirror can be measured from the viewfinder viewing position to the photographing position by operating the shutter button. The photometry element is configured to perform photometry of subject light by retreating to the photographing position.

Then, when the movable mirror has almost completed retracting to the photographing position, the movable means starts to move, and the aperture is narrowed down in accordance with the movement of the aperture preset member that follows the movable means.

The output of the photometric circuit changes as the aperture is stopped down, and when it reaches a predetermined level, the electromagnetic means is activated to stop the movement of the aperture preset member and determine the aperture aperture, but the movable means then continues to move, leaving the aperture preset member behind, and when a certain period of time has elapsed since the movable mirror started retracting to the photographing position, it acts on the shutter front curtain locking member, thereby locking the shutter front curtain. unlock.

As a result, after the shutter front curtain travels to perform exposure, and then when the shutter rear curtain completes its travel, the return means is activated to move the mirror drive member and the movable means back.

At this time, the movable means returns the diaphragm preset member to the position where the diaphragm is fully opened, and the member that is retracted from the electromagnetic means when it is moved in conjunction with the movable means returns the electromagnetic means to the state before activation. let

One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a camera according to the above embodiment,
An interchangeable lens 2, also indicated by a chain line, is removably attached to the camera body 1, which is indicated by a chain line.

The subject light beam that has passed through the photographing lens 3 of this interchangeable lens and the aperture 5 (only two of which are shown to simplify the drawing) is directed to a movable mirror 8 that rotates in conjunction with the depression of the shutter button 12.
is reflected from the front shutter curtain 16 by retreating from the viewfinder observation position where it intersects the photographing optical path of the subject light beam and moving to the photographing position where the light beam entering the camera from the finder eyepiece 15 is blocked, The light enters the photometric element 10, which is disposed at the bottom or side surface of the mirror box of the camera in a position that does not interfere with the photographing light beam.

As this photometric element 10, a device having a fast optical response such as a silicon photodiode is suitable, and an aperture control circuit which receives the output of this photometric element 10 as an input is shown in FIG.

Note that the surface of the front shutter curtain 16 facing the photographing lens 3 is given a certain reflection characteristic.

The diaphragm preset member 7 is in the charge position rotated clockwise in FIG.

When the movable mirror 8 rotates upward in conjunction with the depression of the shutter button and completely retreats from the photographing optical path, completely blocking the photographing room and finder room of the camera, the aperture preset member 7 is moved to its charged position. The lock is released and the aperture 5 has a habit of being narrowed down from its open position via the aperture interlocking pin 6.

This aperture operation continues until the aperture preset member 7 is locked by the aperture electromagnet 20 operated by the output of the aperture control circuit, and the aperture is adjusted to an appropriate value based on the film sensitivity dial 14 and the set shutter speed. After the aperture aperture is determined by the operation of the electromagnet 20, the shutter front curtain 16 is unlocked by the shutter front curtain locking member 17, and the front shutter curtain 16 moves to start exposure.

At the start of exposure, a known shutter control circuit in the electric shutter operates, and when the set exposure time has elapsed, the electromagnet 18 for releasing the rear curtain lock operates, the shutter rear curtain 19 starts running, and the exposure ends. .

To explain in detail the aperture control circuit shown in FIG. 2, this circuit consists of a power supply circuit B consisting of a power supply 21 and a power switch 22 connected in series with the power supply 21 and closed in conjunction with the release operation; A photometric calculation circuit C including the element 10, an aperture control circuit D consisting of an aperture electromagnet 20, a differential switching circuit 26, an aperture holding switch 23 connected between the power supply circuit B and the aperture electromagnet 20, and a shutter speed. It consists of a manual setting circuit E including a variable resistor 13a set by a dial 13.

The photometric calculation circuit C includes an operational amplifier 24 that amplifies the output of the photometric element 10 without applying a voltage across it, and a diode 25 that performs photographic calculation processing on the output of the photometric element 10. It is configured so that a potential difference X proportional to the logarithmic value of the light-receiving surface illuminance of the photometric element 10, that is, the intensity of the subject light incident thereon, is generated at the output end of the operational amplifier 24.

A variable resistor 14a whose resistance value is determined by the film sensitivity setting dial 14 shown in FIG. 1 is connected between the output terminal of the operational amplifier 24 and the power supply circuit B via a constant current source. Potential y generated in the well 14a
The potential of x+y at point P, which is determined by A variable resistor 13a whose resistance value is changed by a dial 13 is connected to a power supply circuit B via a constant current source and a diode, and generates a potential difference 2 at point q, which is connected to the differential switching circuit 2.
6 as the other input.

In the differential switching circuit 26, the light receiving surface of the photometric element 10 gradually decreases due to the narrowing operation of the aperture 5 by the aperture presetting member 7, and the potential at point p gradually decreases to the potential x+y (potential at point p). When the potential difference with potential z (potential at point q) becomes 0, the aperture electromagnet 2, which had been excited by the output of the differential switching circuit 26,
Demagnetize 0.

By demagnetizing the diaphragm electromagnet 20, the diaphragm presetting member 7 which is in the process of diaphragm diaphragm is stopped and stopped, as will be described later, and the diaphragm 5 is set to an appropriate diaphragm aperture.

Although not shown in the figure, as is well known, after the start of exposure, the shutter control circuit sets the potential 2 at point q determined by the resistance value of the variable resistor 13a.
When the charging potential of this capacitor reaches a predetermined level, the output of the switching circuit in the control circuit is inverted to move the shutter electromagnet 18 from its excited state. Change to demagnetized state.

Due to this change in the state of the electromagnet 18, the rear curtain 19 is released from being locked at the charging position, and the rear curtain 19 is activated.
Exposure ends.

3 and 4 show the mechanisms disposed on the side and bottom surfaces of the mirror box, respectively, in a state immediately before the shutter is charged and the release operation is performed.

Set the film sensitivity setting dial 14 shown in FIG. 1 to the sensitivity of the film used, set the aperture preset ring 4 on the interchangeable lens 2 to the minimum aperture, and set the shutter speed dial 13 to the desired shutter speed. When the shutter button 12 is pressed down, it is supported by a shaft 27 on the side wall of the mirror box as shown in FIG.
Release lever 2 with clockwise rotational behavior
9 is rotated counterclockwise in conjunction with the depression of the shutter button, and the electrically insulating pin 29a of the lever 29
This closes the power switch 22, which had been open against its habit, and excites the aperture electromagnet 20.

Next, one end 29b of the release lever 29 engages with the pin 32a of the mirror locking lever 32, and the mirror locking lever 3
2 is rotated clockwise about the shaft 30 against the spring 31 to allow the mirror drive member 35 to rotate clockwise.

The mirror driving member 35 is rotatably supported on the mirror box by a shaft 33, and is given clockwise rotational behavior by a spring 34, and a pin 35a having a semicircular portion formed in one arm thereof is rotatably supported by the mirror box. By engaging with the mirror locking lever 32, rotation in the habitual direction is prevented, but as described above, when the mirror locking lever 32 rotates clockwise based on the release operation, the pin 35a and the locking lever 32 is disengaged, the spring 34 rotates clockwise.

One arm of the mirror driving member 35 has a gripping portion 35b that grips the movable mirror 8, which is rotatably supported on the mirror box by a shaft 8a and has the ability to rotate toward the viewfinder observation position by a spring 8b. A pin 35d to be engaged with a return lever 70, which will be described later, is implanted in the other arm, and a locking member 36 of a drive system, which will be described later, is attached to the other arm during the clockwise rotation stroke of the mirror drive member 35. A pin 35c that engages with and releases the engagement piece 36a is implanted.

Therefore, when the power switch 22 is closed by the release operation and the mirror driving member 35 is unlocked by the mirror locking lever 32, the mirror driving member 35 rotates clockwise and the movable mirror 8 is aligned with the optical axis. On the other hand, it rotates from the finder observation position to the photographing position, which intersects at 45 degrees, and just before the end of this rotation, the locking by the locking member 36 of the drive system is released by the pin 35c.

Note that even if the shutter button 12 is once pressed down and then stopped in the above process, the pin 35a will not move as far as the release lever 29 after the mirror drive member 35 has rotated clockwise.
Since the release lever 29 is held in the counterclockwise rotated position by engaging with the arm 29b, the power switch 22 remains closed.

The drive system consists of a fixed plate 3 fixed to the side wall of the mirror box.
The locking pin 4 has a sliding shaft 40 that is slidably fitted into the guide holes 37a and 37b of No. 7, and the locking pin 4 is implanted in the sliding shaft 40.
0a is rotatably supported on the fixed plate 37 by a shaft 38, and can be engaged in the charging position with the hook portion 36b of the locking member 36 which has a clockwise rotational habit by a spring 39. As described above, when the locking member 36 is rotated counterclockwise by the pin 35c of the locking member 36, the engagement between the two is released.

The drive lever 41, which has a pin 41a that engages with a notch 40b formed in the sliding shaft 40, slides on the sliding shaft 40 from its charging position in the direction of the arrow in FIG. 3, as will be described later with reference to FIG. This gives them the habit of doing so.

Note that the interlocking pin 40c implanted in the arm protruding from the sliding shaft 40 is connected to the fork portion 44a of the slow speed lever 44.
is engaged with.

The slow speed lever 44 is rotatably supported on the side wall of the mirror box by the shaft 33 of the Milani drive member 35,
The sliding shaft 40 is connected by a shaft 46a to a piston 46 that fits into a cylinder 47 of an air damper that is pivotally connected to the mirror box by a shaft 45.Therefore, when the sliding shaft 40 moves in the direction of the arrow from the charging position, it is moved by the air damper. The speed is reduced.

A drive lever 4 that rotates while driving the sliding shaft 40 described above.
1 is rotatably supported by a shaft 42 on the bottom wall of the mirror box, as shown in FIG. 4, and is provided with a counterclockwise rotational habit by a drive spring 43 stretched between the mirror box and the mirror box. .

Further, a lever 48 having a bent piece 48b that can abut and engage with the bent part 41b of the drive lever 41 is supported on the shaft 42, and the lever 48 is also rotated counterclockwise by a spring 49. A connecting lever 51 is rotatably supported on the lever 48 by a shaft 48a, and a clockwise rotational behavior is provided by a spring 52.

The aperture presetting member 7 is rotatably supported on the bottom wall of the mirror box by a shaft 50, and the other end of the spring 49 is applied to one arm of the diaphragm presetting member 7. The U-shaped groove 51b of the connecting lever 51 is fitted and engaged.

The lever 48, the connecting lever 51, the aperture presetting member 7, and the spring 49 constitute a loop-shaped moving body as a whole, and the spring 49 uses the force to overcome the load of the aperture interlocking pin in the interchangeable lens 2 to preset the aperture. Since the loop-shaped moving body is applied to the member 7, the spring 49 and
The spring 52 has a tendency to rotate counterclockwise around the shafts 42 and 50.

A spring 59 is rotatably supported on the shaft 50 of the aperture preset member 7 and elastically installed between the aperture preset member 7 and the aperture preset member 7.
The hook portion 60a formed on the fan-shaped gear 60 having a clockwise rotational habit can be engaged with the hook portion 51a formed on the connecting lever 51, so that the loop-shaped moving body rotates counterclockwise as described above. When rotating, both hook portions 51a, 60
The sector-shaped gear 60 is rotated counterclockwise against the spring 59 by the engagement of point a.

A ratchet 62 coaxial with a pinion 61 that meshes with the sector gear 60 is disposed on the bottom wall of the mirror box, and as described above, when the sector gear 60 rotates counterclockwise, the ratchet 62 rotates clockwise. Rotates in conjunction with .

Furthermore, a lever 54 for absorbing stroke errors, which is supported by a shaft 53 on the bottom wall of the mirror box and biased counterclockwise by a strong spring 55, includes the connecting lever 51.
A protruding portion 51c formed at one end of the battery abuts and engages in the charging completed state.

On the other hand, the stopper 57, which is supported by the shaft 53 and urged clockwise by a weak spring 56, has an armature 58 and a pin 57b attracted by the aperture electromagnet 20 on its first arm, and a pin 57b on its second arm. has a pawl 57a that engages and locks the ratchet 62, and its third arm is engageable with the eccentric pin 54a on the lever 54.

Here, the pin 57b of the first arm opens the diaphragm holding switch 23, which has a closing habit, when the stopper 57 rotates counterclockwise.

Note that the eccentric pin 54a is attached to the raised portion 51 of the connecting lever 51.
In the charging state where c is pressing the lever 54,
The armature 58 is brought into pressure contact with the magnetic pole of the electromagnet 20 by the weak spring 56, so that no gap is created between the stop lever 74 and the eccentric pin 54a (if any, the gap is extremely small). It has been adjusted.

Now, when the power switch 22 is closed by a shirt release operation, that is, by pressing down the release button 12, the electromagnet 20 is excited and attracts and holds the armature 58, which is pressed against its magnetic pole by a spring 56.

Subsequently, in a stroke near the end of the upward rotation of the movable mirror 8, the locking of the sliding shaft 40 by the locking member 36 is released,
The drive lever 41 starts driving the sliding shaft 40 in the direction of the arrow against the braking by the air damper, and the loop-shaped moving body as a whole starts to rotate counterclockwise, and the protrusion 51c of the connecting lever 51 The pressure on the lever 54 is released.

As a result, the lever 54 becomes free and attempts to rotate the stopper 57 counterclockwise via the eccentric pin 54a with the force of the strong spring 55, but the armature 58 is attracted and held by the magnetic pole of the electromagnet 20. Therefore, rotation of the stop lever 57 in the counterclockwise direction is prevented.

On the other hand, the loop-shaped moving body has a drive lever 4 connected to a sliding shaft 40 which is damped by an air damper.
1, the hook 51a of the connecting lever 51 pushes the hook 60a of the fan-shaped lever 60, causing the lever 60 to rotate counterclockwise, causing the ratchet to rotate. 62 in the clockwise direction, the interlocking pin 6 follows the aperture presetting member 7 to gradually narrow down the aperture 5.

Therefore, the subject light that has passed through the diaphragm 5, which is gradually narrowed down, and has been reflected by the shutter front curtain 16, enters the photometric element 10, and the potential x + y at point p in the diaphragm control circuit in FIG. is gradually decreasing.

Then, when this potential x + y becomes equal to the potential 2 at point q, the output of the differential switching circuit 26 is reversed from a low level to a high level, power to the aperture electromagnet 20 is cut off, and the electromagnet 20 is demagnetized. to release the hold on the armature 58.

Therefore, as shown in FIG. 5, the stop lever 57 rotates counterclockwise together with the lever 54 by the force of the strong spring 55, and its pawl 57a locks the ratchet 62, pushing the fan-shaped lever 60 and it. The rotation of the connecting lever 51 that had been
In other words, the counterclockwise rotation of the loop-shaped moving body is stopped.

As a result, the aperture preset member 7 also stops rotating counterclockwise, and the interlocking pin 6 is stopped at that stop position, so the aperture 5
The aperture is also stopped and the aperture aperture is determined.

Even after the above operation is completed, the drive lever 41 remains in that position and rotates counterclockwise as shown in FIG. 5, driving the sliding shaft 40 in the direction of the arrow. 4
The locking pin 40a of No. 0 engages with the pin 17a of the front curtain locking lever 17, which is rotatably supported by a shaft 64 on the bottom surface of the camera body and has a counterclockwise rotational habit by a spring 65. The curtain locking lever 17 is rotated clockwise against its habit.

As a result, the locking arm 17b of the leading-curtain locking lever 17 releases the locking pin 66a of the leading-curtain gear 66, so the leading curtain 16 starts running, and as soon as exposure starts, the leading-curtain locking lever 1
7 starts operating the shirt starter control circuit.

Here, since the stroke from the start of movement of the sliding shaft 40 until its pin 40a engages with the front curtain locking lever 17 is always constant, the stroke from the start of movement of the movable mirror 8 to the photographing position to the time when the shaft locking front curtain is moved is constant. The time until release is always constant,
Even if the aperture bounces immediately after the aperture opening is determined, the aperture will completely stop before the shutter front curtain is released.

In the shirtter control circuit, the shirtter speed dial 13
The capacitor is charged by a current that logarithmically expands the potential 2 at point q generated in the variable resistor 13a determined by , and when the charging potential reaches a predetermined level, the output of the switching circuit is reversed and the electromagnet for the shirt starter, which had been excited until then, is Cut off the power supply to 18.

Therefore, in FIG.
The trailing curtain locking lever 68 that was locking a is no longer locked,
The rear curtain 19 starts running and ends the exposure.

Immediately before the rear curtain 19 completes running, the locking pin 67a on the rear curtain gear 67 is attached to the shaft 7 on the side wall of the mirror box in FIG.
2, and has the tendency to rotate counterclockwise by a spring 69. The return locking member 63 engages with the bent portion 63a of the return locking member 63, and pushes the bent portion 63a counterclockwise in FIG. Then, in FIG. 3, the return locking member 63 is rotated clockwise against the spring 69 to release the lock of the return member 70 by the locking pawl 63b.

The return member 70 is connected to the shaft 33 as shown in FIG.
The mirror driving member 35 and slow speed lever 44 are rotatably supported on the shaft, and a strong spring 71 imparts a counterclockwise rotational habit, and the return member 7 is rotated when the lock is released.
0 counterclockwise rotation engages the return pin 35d of the mirror drive member 35, which is in the clockwise rotation position as described above, and rotates both of them counterclockwise, so that the mirror drive member 35 is in the horizontal photographing position. The movable mirror 8 is rotated back to the observation position at an angle of 45° to the optical axis.

On the other hand, the mirror drive member 35, which rotates counterclockwise, engages with the pin 44b of the slow speed lever 44 and pushes it.
Since the slow speed lever 44 is rotated counterclockwise to return,
The piston 46 of the air damper returns inside the cylinder 47 to the position shown in FIG. 2, and the sliding shaft 40 returns against the drive panel 43 in the direction opposite to the arrow.

With the return of the sliding shaft 40, the front curtain locking lever 17, which had been pressed and rotated by the locking pin 40a, also springs 6.
5 rotates counterclockwise in FIG.

On the other hand, when the drive lever 41 is rotated clockwise in FIG. 5, its bent portion 4lb pushes the lever 48 and rotates both clockwise, thereby rotating the loop-shaped moving body as a whole clockwise. Therefore, the aperture preset member 7 is rotated clockwise by the spring 49, and returns the aperture 5 from its narrowed position to the open state via the aperture interlocking pin 6.

During the return rotation of the aperture preset member 7, the pawl 57a of the stop lever 57 still locks the ratchet 62, so the fan-shaped gear 60 does not follow the return rotation, but the loop-shaped moving body Immediately before the end of the clockwise rotation, the protrusion 51c of the connecting lever 51 engages with the lever 54 to rotate it clockwise.

In accordance with this, the stop lever 57 rotates clockwise by its weak spring 56 to release the ratchet 62 from the pawl 57a, and its armature 58 abuts against the throttle electromagnet 20 with a predetermined pressure.

Finally, by performing a winding operation, one frame of the exposed film is wound up, the shutter is charged, and each member is completely restored to the state shown in FIG.

As explained above, in the instant automatic aperture determination single-lens reflex camera of the present invention, the photometric element is fixed to the camera body, and there is no member to move it between the aperture determination and the start of exposure. Not only can you avoid complicating the configuration, but the actual stopping down of the aperture and the start of metering using the photometering element are started after the movable mirror has retreated to the shooting position and the photometering element has been blocked from the viewfinder optical path. Exposure is not affected by light incident from the eyepiece.

Furthermore, the diaphragm preset member is configured to follow the movable means and move while narrowing down the diaphragm, and after the movement of the diaphragm preset member is stopped by the operation of the aperture control electromagnetic means, only the movable means moves independently. Then, when a predetermined period of time has elapsed since the move of the movable mirror to the photographing position has elapsed, the shutter front curtain locking member is actuated at a constant timing to release the locking of the shirt shutter front curtain. Because of this configuration, it is also possible to avoid starting exposure while the aperture is bouncing immediately after determining the aperture aperture.
Exposure control can always be performed with high precision.

In addition, in the camera of the present invention, by moving the movable means after the movable mirror is retracted, it is possible to follow the aperture presetting member (that is, stop down the aperture), allow the operation of the electromagnetic means for determining the aperture, and release the locking of the front curtain. The movement of the movable means causes the diaphragm preset member to move back (that is, return the diaphragm to full opening).
and the electromagnetic means for aperture determination is configured to return to the state before activation, and one movable means is used as a central member to perform the above-mentioned shooting operation and return operation.
There is also the advantage that these operations can be achieved rationally and reliably without the uncertainty that occurs when starting operations via multiple members in a chain.

In addition, since the photometry element for aperture control is configured to measure the light reflected from the subject light on the shutter front curtain surface, the photometry element must be placed in the camera at a position where it does not block the photographing optical path. Not only can it be fixedly installed, exposure control is always stable without fluctuations in exposure due to the reflection characteristics of the film used, such as in shutter speed control using film surface photometry.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a perspective view showing a schematic configuration of the main parts of the camera in the embodiment, FIG. 2 is an aperture control circuit diagram of the embodiment, and FIG. FIG. 4 is a front view of the side wall of the mirror box of the embodiment in a charged state; FIG. 4 is a front view of the bottom wall of the mirror box in a charged state; FIG. This is a drawing of the camera in a released state. In the figure, 1... Camera body, 2... Interchangeable lens, 4
...Aperture preset ring, 5...Aperture, 6...Aperture interlocking pin, 7...Aperture preset member, 8...Movable mirror, 10...Photometering element, 12...Shutter button, 13...Shutter speed dial, 14...Film sensitivity setting dial, 13a, 14a...Variable resistor, 16...Shutter front curtain, 17...Front curtain locking member, 18...Shutter shutter electromagnet, 19...Shutter shutter rear curtain, 20...Aperture Electromagnet for use, 22
...Power switch, 23...Aperture holding switch, 24...
...Operation amplifier, 26...Differential switching circuit, B...Power supply circuit, C...Photometry calculation circuit, D...Aperture control circuit, E...Manual setting circuit, 29...Release lever, 32...Mirror section Stop lever, 35... Mirror drive member, 36... Locking member, 40... Sliding shaft, 41... Drive lever, 43... Drive spring, 44... Slow speed lever, 4
6, 47...Air damper, 48...Lever, 51...
...Connection lever, 57...Stop lever, 58...Armature, 60...Fan-shaped gear, 62...Ratchet,
63... Return locking member, 70... Return member.

Claims (1)

[Claims] 1. The photographic optical path is blocked within the camera body so that the photographic light path is metered after passing through the photographing lens and its diaphragm and reflected on the side facing the photographing lens of the shutter front curtain having certain reflection characteristics. a photometric circuit C having a photometric element fixed in a position where the movable mirror 8 is not in use; The movable means 40 and 41 start moving almost simultaneously with the completion of evacuation to the photographing position, and the movable means follow these movable means to narrow down the aperture of the photographic lens, and the movable means moves back and forth to narrow down the aperture. an aperture presetting member 7 for returning to the fully open position; and an aperture determining electromagnetic means 20, 54 that operates to stop the movement of the aperture presetting member when the output of the photometric circuit changes to a predetermined level due to the aperture being stopped down. ,55,56,57,58
and a front curtain locking member 17 that releases the shirt shutter front curtain from the lock by a constant stroke movement of the movable means, regardless of the stoppage of movement of the aperture preset member due to the operation of the electromagnetic means; a return means 70 for moving the mirror drive member and the movable means back by the movement of the curtain;
71; and a member 51 that retreats from the electromagnetic means by movement of the movable means and returns the electromagnetic means to the state before activation by the return movement of the movable means. .