JPH0720523A - Camera - Google Patents

Abstract

PURPOSE:To prevent the detecting mulfunction of a shake detection sensor and to effectively demonstrate the function of an image blurring preventing device by making the speed of a shutter curtain slow according to the length of an exposure time. CONSTITUTION:Rotaional shake detected by the pitch-shake sensor 5 and the yaw-shake sensor 6 is outputted to a CPU 14 as an angular displacement output by a shake detection circuit 19. Based on the information, a correction lens 10 is driven by the CPU 14. Thereafter, an exposure action is started and a shutter time is decided based on object luminance (photometry value) by the CPU 14. Then, the curtain speed of a shutter is decided based on whether the shutter time is larger than a prescribed value or smaller than it. That means, when the shutter time decided based on the photometry value is slower than the quickest, the curtain speed is made to be slow according to the length of the shutter time decided based on the photometry value. To put it concretely, the driving voltages of a front curtain driving means 23 and a rear curtain driving means 24 by a shutter control circuit 22 are changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly to a camera having a structure capable of changing the shutter speed of a shutter according to the length of exposure time.

[0002]

2. Description of the Related Art Conventionally, a photographing device having a vibration-proof function is a special-purpose device such as a television camera mounted on an automobile or a helicopter, and is large and expensive. However, in recent years, the progress of consumer-use video camcorders has been remarkable, and small and inexpensive ones having a vibration isolation function are also on the market. The fact that a small and inexpensive shake detection sensor has been put to practical use has a great influence on this background.

By the way, the most hand shake frequency when a human holds a camera is about 1 Hz, and there is a shake of a very low frequency having a band of 0.1 Hz to several tens Hz.
Therefore, the shake detection sensor is required to have sensitivity to detect such a low frequency, and it becomes very sensitive to disturbance. A particular problem in a still camera is that the shake detection sensor causes a detection error due to an impact.

In an SLR (single-lens reflex) camera, there are shocks when the mirror is up and down, and shocks when the focal plane shutter is running. When such a shock is applied, the shake detection sensor causes a detection error. Since the correction means for correcting the image shake makes a correction according to the output of the shake detection sensor, if a detection error occurs, the correct correction may not be performed and the image may be deteriorated.

From the above viewpoint, some proposals have been made for a method of preventing image deterioration due to a detection error due to impact.

For example, Japanese Patent Laid-Open No. 4-158342 and Japanese Patent Laid-Open No. 4-195127 disclose a detection method in which the time constant of the shake detection sensor is changed in order to reduce the detection error due to impact. .

Further, in Japanese Patent Laid-Open Nos. 4-175735 and 4-181933, the time lag from the completion of mirror up to the start of exposure is lengthened to wait until the detection error of the shake detection sensor is reduced, and then the exposure is performed. Has been proposed.

[0008]

However, the method of changing the time constant of the shake detection sensor proposed in JP-A-4-158342 and JP-A-4-195127 is, It means worsening, and narrowing the detection bandwidth. Therefore, as a matter of course, there is a drawback that the image blur suppression rate in the band that should be originally reduced becomes poor and the image stabilizing effect is reduced.

Further, the method of prolonging the time lag from completion of mirror up to start of exposure proposed in Japanese Patent Laid-Open Nos. 4-175735 and 4-181933 is a detection mirror caused by a shock of mirror up. However, there is no improvement effect on the impact caused by running the front curtain of the focal plane shutter. In addition, there is a demerit that the release time lag increases.

Further, the impact sound of the shutter and the camera shake due to the impact have been problems as items to be conventionally reduced regardless of the vibration isolation.

It is an object of the present invention to effectively detect erroneous detection of a shake detection sensor more effectively than the prior art in consideration of the fact that the above-mentioned prior art cannot obtain a remarkable effect in preventing image blur of a camera. It is an object of the present invention to provide a camera capable of preventing the operation and having the function of effectively exhibiting the function of the image blur prevention device.

[0012]

Considering the detection error due to the impact of the shutter movement of the front curtain, since the front curtain is the start of exposure, the method of stabilizing the shake detection sensor is impossible. Therefore, the most direct and promising method is to reduce the impact of running the first curtain.

Therefore, if the shutter speed of the shutter is slowed, the impact is naturally reduced, but there is a demerit that the fastest shutter speed and the fastest shutter speed at which the flash can be synchronized are delayed, which makes the product attractive. It is not realistic because it will decrease sharply.

By the way, considering the image blur caused by the camera shake, it is well known that the image blur becomes larger as the exposure becomes longer and the long focus lens becomes longer.

That is, in the case of short-time exposure, the image shake amount per exposure time is small, and there is no influence because the image shake amount is within the permissible circle of confusion. Generally, it is said that there is no influence of image shake due to camera shake when the exposure time is shorter than the exposure time represented by the reciprocal of the focal length of the photographing lens.

For example, when photographing is performed using a photographing lens having a focal length of 300 mm, it is said that the influence of image blur caused by camera shake falls within the permissible circle of confusion when the exposure time is shorter than 1/300 second. . Therefore, when considering the image stabilization for the still camera, it can be said that the image stabilization is required for the long-time exposure.

As described above, the shutter speed of the shutter is required to be high at the time of high-speed shutter, and does not need to be high at the slow shutter speed such as the above-mentioned case where the image stabilization is required. Further, with regard to stroboscopic photography, it can be considered that there is almost no influence of camera shake because the exposure time is extremely short during stroboscopic light emission. Therefore, by slowing the shutter curtain speed during shooting at slow shutter speeds that require image stabilization, it is possible to reduce the impact of running the shutter curtain without causing any demerits. It is possible to eliminate or drastically reduce the detection error of the shake sensor due to impact.

Based on the above idea, in the present invention, the curtain speed changing means for changing the shutter speed of the shutter is provided, and the shutter speed of the shutter is changed according to the length of the exposure time. It is possible to eliminate or drastically reduce the detection error of the shake sensor due to the impact of running the shutter curtain without occurring.

At the same time, the impact noise due to the shutter running and the camera shake due to the impact are reduced,
A camera with improved quality and performance can be realized.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a camera constructed by applying the present invention will be described below with reference to the drawings.

<First Embodiment> A first embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 2 is a perspective view showing the outline of the camera of this embodiment. 1 is a camera body, 2 is a release button for the photographer to start the photographing operation of the camera, and 3 is for guiding the subject light to the viewfinder. The quick return mirror 4 is a pentaprism for erecting the subject image. Reference numeral 5 denotes a pitch shake sensor that detects the rotation shake of the camera in the pitching direction, and has sensitivity in the rotation direction around the axis 5a. 6
Is a yaw shake sensor that detects the rotational shake of the camera in the yawing direction, and has sensitivity in the rotation direction around the axis 6a. 7
Is a photographing lens, which is composed of a first lens group 8, a second lens group 9, a third lens group 10, and a fourth lens group 11.

The third lens group 10 has arrows X and Y in the figure.
The lens is movably held in the direction
Is configured as a correction lens configured to move the image in the X and Y directions by moving in the direction. Reference numerals 12 and 13 denote correction driving means for moving the correction lens 10 in the X and Y directions.

FIG. 3 is a perspective view showing a shutter mechanism mounted on the camera of this embodiment.

In the figure, 41 is a shutter base plate having an exposure window 100. Reference numerals 36 and 36 'are front curtain drive arms. The arm 36 has a front curtain drive shaft 3 at one end.
5, the shaft 35 and the arm 36 are rotatably attached to the shutter base plate 41. Also arm 36 '
Also, one end is rotatably attached to the shutter base plate 41. Light-shielding thin plate-shaped front curtain blades 42-1, 42-2, 42-3 are provided on the arms 36, 36 'with a pin 42.
They are rotatably attached by a, 42b, 42c, 42d, 42e and 42f.

38 and 38 'are trailing blade drive arms.
The arm 38 is fixed to the trailing blade drive shaft 37 at one end,
The arm 38 and the shaft 37 are rotatably attached to the shutter base plate 41. Also, one end of the arm 38 'is also rotatably attached to the shutter base plate 41. The arms 38, 38 'have a thin plate-like trailing blade 4 having a light-shielding property.
3-1, 43-2, 43-3 are pins 43a, 43b, 4
They are rotatably attached by 3c, 43d, 43e and 43f. Reference numeral 65 is a frame of an electromagnetic drive source, and the frame 65 is fixed to the camera body. 6
Reference numeral 2 is a permanent magnet magnetized in the diametrical direction, and the magnet 62 is fixed. Reference numeral 66 denotes a shutter curtain drive coil, which is fixed to the drive shaft 35. Drive shaft 3
5 is rotatably supported in the support holes 65a and 65b of the frame 65, and the coil 66 is rotatable with respect to the yoke 61 that is fixedly installed at a distance from the permanent magnet 62. Although the electromagnetic drive source for the shutter front curtain is shown in FIG. 3, the electromagnetic drive source for the shutter rear curtain is also configured similarly to rotate the shaft 37.

FIG. 4 is a block diagram showing a control circuit mounted on the camera of this embodiment.

14 is the integration of the operation of all the devices of the camera,
Central arithmetic processing circuit (hereinafter CPU
Enter. ). Reference numeral 15 is a photometric circuit for measuring the brightness of the subject by a photometric device (not shown). Reference numeral 16 is a distance measuring circuit for measuring the distance to the subject by a distance measuring device (not shown). Reference numeral 17 is a lens control circuit that controls reading of information of the photographing lens, focus driving, diaphragm driving, and the like. Reference numeral 18 is a mirror control circuit that controls the drive and state detection of the quick return mirror, and 19 is a shake detection circuit that drives the shake detection sensors 5 and 6 to detect shake of the camera. A shutter control circuit 22 controls the operation of the shutter mechanism shown in FIG. 23 is the above-mentioned yoke 6
1, a front curtain drive means composed of a permanent magnet 62, a frame 65, a coil 66, and a drive shaft 35. Reference numeral 24 is a rear curtain driving means (not shown) having the same structure as the front curtain driving means 23. 25
Is a shake correction control circuit for correcting the image shake by driving the correction lens 10 by the correction driving means 12 and 13 according to the shake state of the camera detected by the shake detection circuit 19. 26 is a switch 1 (SW which is turned on when the release button 2 is half pressed).
In 1), the CPU 14 or the like is activated to prepare for shooting. 27 is a switch 2 that is turned on by fully pressing the release button
The shooting operation is started by (SW2). 27 is a switch 3 (SW3) which is turned on and off by an external operation.
When in the N state, the camera shoots with the image stabilization function.

The operation of the camera of this embodiment having the above-mentioned structure will be described with reference to the flow chart shown in FIG.

When the photographer half-presses the release button 2 to turn on SW1, the CPU 14 is activated to detect the state of SW3. If SW3 is in the ON state, the shake detection circuit 19 activates the shake sensors 5 and 6. Next, the lens control circuit 17
Various information such as the focal length of the currently used shooting lens and the open F number are captured via. Next, photometric circuit 1
The brightness information of the subject detected in 5 is taken in, and the aperture value (Av) and the shutter speed (Tv) are determined according to a preset program. Next, the focus detection amount to the object detected by the distance measuring circuit 16 is calculated, and if the focus state is not achieved, the focus movement amount of the photographing lens is calculated and the lens control circuit 17 focuses the focus lens drive. Repeat until When the focus state is reached, the state of SW3 is checked again, and when it is ON, the shake correction control circuit is activated, and the correction drive means 12 and 13 are driven based on the camera shake information detected by the shake detection circuit 19. Then, the image blur correction is performed by moving the correction lens 10.

Here, the outline of the system for image blur correction will be briefly described.

Image shake due to camera shake is caused by movement of the image on the image plane (film surface) due to camera shake during the exposure time. Therefore, by detecting this camera shake and moving the image by the same amount in the opposite direction to the movement of the image caused by the camera shake in real time, the image does not move even if the camera shakes. That is what is called anti-vibration. In the camera of the present embodiment, image stabilization is performed against camera pitching and yawing shake, which are the most dominant factors of image shake. In principle, the camera shake detection may detect any of angular displacement, angular velocity, and angular acceleration. In the camera of this embodiment, a sensor for detecting angular velocity such as a vibration gyro is used as the shake detection sensors 5 and 6. . Shaft 5a detected by pitch shake sensor 5 (yaw shake sensor 6)
The rotational shake around (6a) is output to the CPU 14 as an angular displacement output by the shake detection circuit 19. The CPU 14 integrates the output value to obtain angular displacement information, and drives the correction lens 10 based on the angular displacement information. Since the relationship between the shake displacement angle of the camera and the drive amount of the correction lens 10 changes depending on the type of the taking lens, the focal length value, the focus value, etc., the angular displacement output and the correction lens drive amount of the correction lens drive amount based on the information of the lens control circuit 17. A coefficient is determined, and a shake correction operation is performed based on a value obtained by multiplying the angular displacement output by the coefficient. The shake correction control circuit drives the vertical correction drive means 13 (horizontal correction drive means 12) to position the correction lens 10 at a position according to the camera shake displacement angle output in the pitching direction (yaw direction) calibrated by the CPU 14. The drive control constitutes a closed loop control using a position detection output (not shown) of the correction lens 10 with the displacement output as a target, and performs shake correction in real time according to camera shake.

After that, the CPU 14 operates the SW2 (O
When the photographer further presses the release button to turn on SW2, the CPU 14 starts the exposure operation.

First, based on the subject brightness (photometric value), T
The v value, that is, the shutter speed is determined, and the shutter speed is determined depending on whether the Tv value is larger or smaller than the predetermined shutter speed. The shutter speed of the shutter is determined from the viewpoint of reducing the impact of the shutter.
For example, in the case of a camera having the fastest shutter time of 1/3000 second, if the shutter time determined based on the photometric value is slower than the fastest shutter time, the shutter time determined based on the photometric value. The curtain speed is slowed according to the length of. Specifically, the shutter control circuit 22
This is achieved by changing the drive voltage of the front curtain driving means 23 (rear curtain driving means 24). That is, the traveling speed of the shutter curtain is freely changed by changing the voltage applied to the coil 66 which is the driving means for driving the shutter curtain.

Next, the mirror control circuit 18 is used to raise the mirror to switch the object light from the finder to the film surface, and then the shutter control circuit 22 sets the front curtain drive means 23 at the previously determined curtain speed. To drive the front curtain 42. After that, the rear curtain driving means 24 is operated by the shutter control circuit 22 according to the Tv value (shutter second) determined according to the subject brightness in order to obtain appropriate exposure.
To drive the rear curtain 43 to complete the exposure. When the traveling of the rear curtain is completed, the mirror control circuit again performs mirror down, the object light is switched to the finder, the shutter is restored, and the release operation is completed.

<Second Embodiment> FIGS. 5 and 6 show a second embodiment of the present invention. The same members as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted here. Figure 1 is the first
FIG. 4 is a perspective view showing a shutter mechanism corresponding to FIG. 3 showing an embodiment. In the first embodiment, the drive source of the shutter is an electromagnetic drive source, whereas in the present embodiment, spring force drive is used. In FIG. 5, 101 is a front curtain gear, and a gear portion 101a is formed on the outer peripheral portion thereof and is fixed to the front curtain drive shaft 35. Reference numeral 102 denotes a leading blade spring which is a leading blade driving source, and is arranged coaxially with the leading blade driving shaft 35, one end of which comes into contact with a dowel 103 planted in the shutter base 41, and the other end of which is the leading blade gear 101. By engaging with the front curtain drive shaft 3
5 is urged clockwise. Reference numeral 104 denotes a speed-up gear, which is rotatably held around a shaft 104a and has a gear portion 101a
And the rotation of the front curtain drive shaft 35 is accelerated. 10
A rotor 5 is fixed to the speed increasing gear 104 coaxially with the shaft 104a, and forms a plurality of permanent magnet portions polarized in the radial direction (radial direction) with respect to the shaft center. Reference numeral 106 denotes a yoke, and symmetrical arm portions 106a and 106b are arranged so as to face a predetermined pole of the permanent magnet portion, and a coil 107 is wound around the central portion to form an electromagnet.

FIG. 6 is a block diagram showing the control circuit of the camera of this embodiment. An electromagnet drive circuit 108 is newly added to the block diagram of FIG. 4 showing the first embodiment. The electromagnet circuit 108 controls the amount of current supplied to the winding coil 107 according to a command from the central processing circuit 14.

The operation of the camera of this embodiment having the above structure will be described with reference to the flow chart shown in FIG. First, since the shutter mechanism portion of the camera of this embodiment is different from that of the first embodiment, its description will be given. Although the shutter curtain travels to perform exposure with the release operation of the photographer, the shutter mechanism of this embodiment operates because the camera of this embodiment currently uses the most popular spring driven shutter. It is similar to that of conventional cameras.

That is, when the tension of the front curtain is released by an electromagnet (not shown), the front curtain drive shaft 35 is rotated clockwise by the urging force of the front curtain spring 102, and the front curtain is moved via the front curtain drive arm 36. The blades 42-1, 42-2, 42-3 are driven to open.

At this time, since the front curtain gear 101 rotates, the speed increasing gear 104 meshing with the front curtain gear 101 also rotates, and the rotor 105 also rotates. When a current is applied to the coil 107, the arm portions 106a and 106b of the yoke 106 become electromagnets forming different poles, so that the pole and the rotor 10
The magnetic force acts between the permanent magnet portion 5 and the permanent magnet portion 5 to act as a resistance force that hinders the rotation of the rotor 105. Therefore, the rotor and the electromagnet serve as an electromagnetic governor that applies a braking force to the gear 101.

Next, the release operation of the camera will be described with reference to the flowchart of FIG.

From the SW2 waiting state, when the photographer further presses the release button to turn on SW2, the camera starts the release operation. The shutter speed of the shutter is determined based on the Tv value determined by the subject brightness (this shutter speed determination is performed by the same method as in the first embodiment). The electromagnet drive circuit 108 determines the shutter speed based on the shutter speed value. An appropriate current is passed through the winding coil 107. Next, after the mirror control circuit 18 performs the mirror-up operation, the shutter control circuit 22 operates an electromagnet (not shown), which is a front curtain driving means, to release the tension of the front curtain and allow the front curtain to run. Then, the front curtain travels at a speed corresponding to the amount of current to the coil 107 to start exposure. After that, the shutter control circuit 22 operates an electromagnet (not shown), which is the trailing-curtain driving means, according to the Tv value determined according to the brightness of the subject in order to obtain proper exposure, thereby releasing the tension of the trailing curtain. Then, the rear curtain is run to complete the exposure. The drive mechanism for the trailing curtain also uses a spring force as a drive source, like the leading curtain, but the speed adjusting mechanism by the electromagnetic governor used for the leading curtain may or may not be present in the trailing curtain driving mechanism. both are fine. This is because, in the case of the rear curtain, the traveling is completed, that is, the exposure is completed, and it is considered that the impact at the completion of traveling does not affect the exposure. When the driving of the rear curtain is completed, the mirror control circuit 18 is restarted.
Then, the mirror is down and the shutter is returned to complete the shooting operation. In this case, the shutter return means the return of the shutter mechanism and the charge of the spring that drives the shutter, and it is a known type such as a type linked with mirror down or a type linked with film winding.

<Third Embodiment> FIGS. 7 and 8 show a third embodiment of the present invention. The same members as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted here. The camera of the present embodiment is different from the first embodiment in the shutter mechanism and has the shutter mechanism shown in FIG.

In FIG. 7, a front curtain gear 120 has a gear portion 120a formed on the outer periphery thereof and is fixed to the front curtain drive shaft 35. 121 is a front curtain spring which is a front curtain drive source, and is arranged coaxially with the front curtain drive shaft 35.
The end is a dowel 122 planted in the shutter base plate 41.
, And the other end engages with the front curtain gear 120 to urge the front curtain drive shaft 35 in the clockwise direction. Reference numeral 123 denotes a pinion gear, which is fixed to the rotary shaft of the leading blade motor 124 and meshes with the gear portion 120a of the leading blade gear 120. The first-curtain motor 124 returns the first-curtain and the first-curtain spring 121.
Although it is a motor for charging and charging, it rotates as the front curtain travels, and therefore acts as a load resistance if a voltage is applied in the opposite driving direction. Therefore, the curtain speed can be changed by adjusting the applied voltage.

FIG. 8 is a block diagram showing the control circuit of the camera of this embodiment. A shutter charge circuit 126 for driving the front curtain motor and the rear curtain motor is further added to the configuration of the first embodiment.

The camera of the present embodiment having the above-described structure operates in accordance with the flowchart of FIG. 1 similarly to the cameras of the respective embodiments, but the camera of the present embodiment differs from the cameras of the respective embodiments only in the shutter mechanism. Therefore, the operation of the shutter mechanism will be mainly described below.

When the release button is further depressed by the photographer's release operation and SW2 is turned on, the CPU 14 starts the exposure operation. First, the shutter speed of the shutter is determined based on the Tv value determined by the subject brightness by the method described above, and the shutter charge circuit 12 is determined based on the shutter speed.
6 applies an appropriate voltage to the front curtain motor 124. Next, after the mirror control circuit 18 performs the mirror-up operation, the shutter control circuit 22 actuates an electromagnet (not shown), which is a front curtain driving means, to release the tension of the front curtain and allow the front curtain to run. Then the first curtain motor 12
The front curtain travels at a speed corresponding to the voltage applied to No. 4 to start exposure. After that, the shutter control circuit 2 is based on the Tv value determined according to the subject brightness in order to obtain proper exposure.
An electromagnet (not shown), which is a trailing-curtain driving unit, is activated by 2 and the tension of the trailing curtain is released, and the trailing curtain is run to complete the exposure. The driving and charging mechanism for the trailing curtain is the same as the driving and charging mechanism for the leading curtain, but the curtain speed adjustment by the trailing motor 125 is not necessary for the reason explained in the second embodiment. But either one is fine. When the traveling of the rear curtain is completed, the mirror control circuit 18 performs the mirror down again, and the shutter charge circuit 126 drives the front curtain motor 124 and the rear curtain motor 125 to restore the shutter and charge the drive spring to perform the photographing operation. Is complete.

In the configuration of this embodiment, the front curtain motor 124
It is possible not only to make the (rear curtain motor 125) act as a load resistance but also to act as a driving force.
Since a driving force can be obtained by applying a voltage in the direction opposite to the load direction described above, it is possible to achieve a faster shutter time than the fastest shutter time determined by the front curtain spring 121.

[0049]

As described above, in the camera of the present invention, when the exposure time determined based on the photometric value is longer than the predetermined exposure time, the exposure determined based on the photometric value. Since the shutter curtain speed is controlled to slow down the shutter curtain speed according to the length of time, the impact and noise due to the running of the shutter curtain is significantly reduced compared to conventional cameras when shooting with long exposure times. To do. Therefore, according to the camera of the present invention, there is almost no camera shake at the time of shooting with a long exposure time as compared with the conventional camera, and therefore there is almost no risk of shooting failure. With the camera to which the present invention is applied, the performance of the image blur prevention device can be maximized.

[Brief description of drawings]

FIG. 1 is a flowchart showing operations and functions of a camera of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a camera according to first to third embodiments of the present invention.

FIG. 3 is a perspective view showing a main part of a shutter mechanism mounted on the camera of the first embodiment.

FIG. 4 is a block diagram showing an outline of an electronic control unit of the camera of the first embodiment.

FIG. 5 is a perspective view showing a main part of a shutter mechanism of a camera of a second embodiment.

FIG. 6 is a block diagram showing an outline of an electronic control device for a camera of a second embodiment.

FIG. 7 is a perspective view showing a main part of a shutter mechanism of a camera of a third embodiment.

FIG. 8 is a block diagram showing an outline of an electronic control device for a camera of a third embodiment.

[Explanation of symbols]

1 ... Camera body 2 ... Release button 3 ... Quick return mirror 4 ... Penta prism 5,6 ... Shake sensor 7 ... Photographing lens 10 ... Correction lens 12, 13 ... Correction drive means 41 ... Shutter base plate 35 ... Front curtain drive shaft 37 ... Rear curtain drive shafts 42-1 to 42-
3 ... Front curtain blades 43-1 to 43-3 ... Rear curtain blade 61 ... Yoke 62 ... Permanent magnet 66 ... Shutter curtain drive coil 14 ... Central arithmetic processing circuit 101, 120 ...
Front curtain gears 102, 121 ... Front curtain spring 104 ... Accelerating gear 105 ... Rotor 106 ... Yoke 107 ... Coil 123 ... Pinion 124 ... Front curtain motor 125 ... Rear curtain motor

Claims (3)

[Claims] 1. A camera having a photometric device and exposure condition calculation means for determining an exposure time based on a photometric value obtained by the photometric device, wherein a driving force applied to a shutter curtain can be changed. When the exposure time determined by the shutter curtain driving force control means and the exposure condition calculation means based on the photometric value is longer than a predetermined exposure time, the length of the exposure time determined based on the photometric value A shutter curtain speed changing means for controlling the shutter curtain driving force control means so as to reduce the speed of the shutter curtain according to the above. 2. A photometric device, exposure condition calculation means for calculating exposure conditions such as exposure time based on the photometric value obtained by the photometric device, a focal plane shutter,
A first electromagnetic driving member that applies a driving force to the front curtain of the shutter, a second electromagnetic driving member that applies a driving force to the rear curtain of the shutter, and a control that controls the first and second electromagnetic driving members. And a means for exposing the exposure time determined by the exposure condition calculation means when the exposure time determined by the exposure condition calculation means based on the photometric value is longer than a predetermined exposure time. A camera comprising shutter curtain speed changing means for changing the drive control of the first and second electromagnetic drive members according to the length to reduce the speed of the shutter curtain. 3. A shake detecting means for detecting a shake of a camera, an image shake correcting means for correcting an image shake on an image forming surface according to a detection value of the shake detecting means, a photometric device, and the photometric device. In a camera having an exposure condition calculation means for calculating the exposure condition such as the exposure time based on the photometric value obtained by the above, and an exposure condition setting means for manually setting the exposure condition, A shutter curtain driving force control means that can change the applied driving force, and, according to the length of the exposure time determined by the exposure condition calculating means when the exposure time determined by the exposure condition calculating means is longer than a predetermined exposure time. And shutter shutter speed changing means for controlling the shutter curtain driving force control means so as to slow down the shutter curtain speed.