Exposure control apparatus for camera with shake countermeasure

Claims

What is claimed is:

1. An exposure control apparatus for a camera comprising:

shake amount detecting means for repeatedly detecting shaking of a camera in a sampling time interval shorter than a hand shaking cycle;

exposure calculating means for calculating a shutter speed concerning an opening of a shutter of said camera based on a sensitivity of a film to be loaded in said camera and brightness information of a object to be picked up by said camera;

data processing means for acquiring processed data from a product of said shutter speed calculated by said exposure calculating means and an amount of shaking detected by said shake amount detecting means every time said amount of shaking is detected by said shake amount detecting means;

storage means for storing said processed data output from said data processing means;

shake amount predicting means for receiving said processed data from said data processing means and said processed data stored in said storage means to predict a total amount of shaking while said shutter is open, every time said processed data is output from said data processing means;

a release switch for preparing for beginning of an exposing operation on said film;

shutter enable discriminating means for discriminating permission of a shutter release when a latest predicted total amount of shaking during shutter opening, output from said shake amount predicting means, is equal to or smaller than a predetermined amount, every time said release switch is operated and said shake amount predicting means predicts said total amount of shaking; and

shutter control means for starting opening said shutter based on a signal from said shutter enable discriminating means and controlling an exposure time based on said shutter speed calculated by said exposure calculating means.

2. An exposure control apparatus according to claim 1, wherein said shutter enable discriminating means makes discrimination in light of a shutter time lag from the beginning of said shutter opening to the beginning of actual exposure.

3. An exposure control apparatus according to claim 1, wherein said shake amount predicting means performs prediction by linear approximation.

4. An exposure control apparatus according to claim 1, wherein said shake amount predicting means performs prediction using fuzzy prediction.

5. An exposure control apparatus for a camera comprising:

shutter-speed determining means for determining a shutter speed concerning an opening of a shutter of a camera;

shake amount detecting means for detecting an amount of shaking of said camera for each sampling time;

shutter timing generating means for generating a shutter release signal to instruct an exposing operation of a film loaded into said camera;

maximum wait time determining means for determining a maximum wait time from generation of said shutter release signal from said shutter timing generating means to generation of a shutter enable signal based on an output of said shutter-speed determining means;

allowable shake amount determining means for determining a maximum allowable amount of shaking based on said output of said shutter-speed determining means;

minimum value storage means for storing a minimum value of said amount of shaking output from said shake amount detecting means;

expected shake amount determining means for determining an expected amount of shaking of a looser reference than said minimum value of said amount of shaking stored in said minimum value storage means based on said minimum value;

timer means for measuring time from generation of said shutter release signal from said shutter timing generating means;

comparator means for comparing an output of said timer means with said maximum wait time determined by said maximum wait time determining means;

multiplexer means for receiving an output of said comparator means, outputting said expected amount of shaking determined by said expected shake amount determining means until said maximum wait time elapses, and outputting said allowable amount of shaking determined by said allowable shake amount determining mean after said maximum wait time elapses; and

shutter enable signal output means for comparing an output of said shake amount detecting means with an output of said multiplexer means and outputting said shutter enable signal when a comparison result indicates a predetermined relationship.

6. An exposure control apparatus according to claim 5, wherein said expected shake amount determining means acquires said expected amount of shaking by multiplying said minimum value of said amount of shaking by a constant.

7. An exposure control apparatus according to claim 5, further comprising focus distance detecting means for detecting a focus distance of a zoom lens of said camera, and wherein said maximum wait time determining means determines said maximum wait time using said focus distance detected by said focus distance detecting means in addition to said shutter speed, and said allowable shake amount determining means determines said allowable amount of shaking using said focus distance detected by said focus distance detecting means in addition to said shutter speed.

8. An exposure control apparatus for a camera comprising:

shake amount detecting means for detecting amount of shaking of a camera for each sampling time interval shorter than a hand shaking cycle;

shutter-speed determining means for determining a shutter speed concerning an opening of a shutter of a camera;

compensation means for compensating for said amount of shaking detected by said shake amount detecting means with said shutter speed determined by said shutter-speed determining means;

storage means for storing a shake compensation value output from said compensation means;

prediction means for predicting a total amount of shaking during exposure of a film loaded in said camera by opening of said shutter from a current shake compensation value compensated by said compensation means and a previous shake compensation value stored in said storage means, every time said shake amount detecting means detects said amount of shaking; and

discriminating means for discriminating whether or not said exposure should be started based on said total amount of shaking acquired by said prediction means, in response to a shutter release signal to prepare for beginning of said exposure.

9. An exposure control apparatus according to claim 8, wherein said compensation means divides said shutter speed by said sampling time and computes a product of said amount of shaking and a result of the division.

10. An exposure control apparatus according to claim 8, wherein said discriminating means makes discrimination in light of a shutter time lage from the beginning of said shutter opening to the beginning of actual exposure.

11. An exposure control apparatus for a camera comprising:

shake amount detecting means for detecting amount of shaking of a camera for each sampling time interval shorter than a hand shaking cycle;

storage means for storing a shake compensation value output from said shake amount detecting means;

prediction means for predicting an amount of shaking from a current amount of shaking and a previous amount of shaking stored in said storage means, every time said shake amount detecting means detects said amount of shaking;

shutter-speed determining means for determining a shutter speed concerning an opening of a shutter of a camera;

compensation means for compensating for said amount of shaking predicted by said prediction means with said shutter speed determined by said shutter-speed determining means to acquire a total amount of shaking during opening of said shutter; and

discriminating means for discriminating whether or not exposure of a film loaded in said camera should be started based on said total amount of shaking acquired by said prediction means, in response to a shutter release signal to prepare for a shutter opening operation.

12. An exposure control apparatus for a camera comprising:

shake amount detecting means for detecting amount of shaking of a camera for each sampling time interval shorter than a hand shaking cycle;

storage means for storing a shake compensation value output from said shake amount detecting means;

prediction means for predicting an amount of shaking from a current amount of shaking and a previous amount of shaking stored in said storage means, every time said shake amount detecting means detects said amount of shaking;

shutter-speed determining means for determining a shutter speed concerning an opening of a shutter of a camera; and

discriminating means for comparing an amount of shaking output from said prediction means with a predetermined value determined by said shutter speed determined by said shutter-speed determining means in response to a shutter release signal to prepare for a shutter opening operation to thereby discriminate whether or not exposure of a film loaded in said camera should be started.

13. An exposure control apparatus for a camera for starting an exposing operation with an exposure time based on at least a brightness of an object to be picked up and a sensitivity of a film in response to a release signal from a release operation member, comprising:

output means for outputting information about said exposure time;

detecting means for repeatedly detecting an amount of shaking of said camera in a predetermined detection interval;

processing means for repeatedly detecting an amount of shaking of said camera in a predetermined detection interval;

processing means for processing said amount of shaking detected by said detecting means based on said exposure time information from said output means;

storage means for repeatedly storing an output value of said processing means;

prediction means for predicting an amount of shaking in said exposure time from a currently processed output value from said processing means and a previously processed value stored in said storage means in a case where said exposing operation is started after a predetermined period of time; and

determining means for determining whether or not said exposing operation should be started after said predetermined period of time based on an output of said prediction means.

14. An exposure control apparatus according to claim 13, wherein said processing means performs a computation given below:

m.times.S/.DELTA.t

where m is said amount of shaking detected by said detecting means, s is said exposure time information from said output means, and .DELTA.t is said shake detection interval in said detecting means.

15. An exposure control apparatus according to claim 13, wherein said prediction means predicts said amount of shaking by a fuzzy prediction.

16. An exposure control apparatus according to claim 13, wherein said determining means permits said exposing operating to be started when said amount of shaking predicted by said prediction means becomes equal to or less than a predetermined allowable amount.

17. An exposure control apparatus for a camera for detecting an amount of shaking of a camera in response to a release signal from a release operation member, acquiring from said detected amount of shaking a timing at which an influence of shaking on film exposure and starting an exposing operation at said timing, comprising:

exposure time calculating means for acquiring information of an exposure time based on at least a brightness of an object to be picked up and a sensitivity of a film;

detecting means for repeatedly detecting an amount of shaking of said camera in a predetermined detection interval;

processing means for processing said amount of shaking detected by said detecting means based on said exposure time information acquired by said exposure time calculating means;

storage means capable of repeatedly storing a value processed by said processing means;

prediction means for predicting an amount of shaking in said exposure time from a value currently processed in said processing means and a previously processed value stored in said storage means in a case where said exposing operation is started after a predetermined period of time; and

determining means for determining whether or not said exposing operation should be started after said predetermined period of time based on an output of said prediction means, said determining means including an allowable shake amount calculating circuit for calculating an allowable amount of shaking from a focus distance of a lens, a comparator for comparing said allowable amount of shaking with said predicted amount of shaking from said prediction means, and a circuit for outputting a shutter-open enable signal when said predicted amount of shaking is detected to be equal to or small than said allowable amount of shaking in said comparator.

18. An exposure control apparatus according to claim 17, wherein said processing means performs a computation given below:

m.times.S/.DELTA.t

where m is said amount of shaking detected by said detecting means, s is said exposure time information from said output means, and .DELTA.t is said shake detection interval in said detecting means.

19. An exposure control apparatus according to claim 17, wherein said prediction means predicts said amount of shaking by a fuzzy prediction.

20. An exposure control apparatus according to claim 17, wherein said determining means further includes a limit time calculating circuit for acquiring a delay limit time from said focus distance of said lens, a timer circuit for starting measuring time in response to said release signal, a second comparator for comparing an output of said timer circuit with said limit time, and a control circuit for forcibly outputting said shutter-open enable signal when said output of said timer circuit is detected to have exceeded said limit time in said second comparator.

21. An exposure control apparatus according to claim 17, wherein said determining means further includes second storage means for storing a minimum value of said predicted amount of shaking output from said prediction means, an expected shake amount calculating circuit for acquiring an expected amount of shaking greater by a predetermined amount than said minimum value of said predicted amount of shaking from am output of said second storage means, a limit time calculating circuit for acquiring a delay limit time from said focus distance of said lens, a timer circuit for starting measuring time in response to said release signal, a second comparator for comparing an output of said timer circuit with said limit time, and a replacing circuit for replacing said allowable amount of shaking in said first comparator with said expected amount of shaking when said output of said timer circuit is detected to have exceeded said limit time in said second comparator.

22. An exposure control apparatus for a camera for detecting an amount of shaking of a camera in response to a release signal from a release operation member, acquiring from said detected amount of shaking a timing at which an influence of shaking on film exposure and starting an exposing operation at said timing, comprising:

exposure time calculating means for acquiring an exposure time based on at least a brightness of an object to be picked up and a sensitivity of a film;

detecting means for repeatedly detecting an amount of shaking of said camera in a predetermined detection interval;

storage means capable of repeatedly storing a value detected by said detecting means;

prediction means for predicting an amount of shaking in said exposure time from a value currently detected by said detecting means and a previously detected value stored in said storage means in a case where said exposing operation is started after a predetermined period of time; and

determining means for determining whether or not said exposing operation should be started after said predetermined period of time based on an output of said prediction means.

23. An exposure control apparatus according to claim 22, wherein said prediction means predicts said amount of shaking by a fuzzy prediction.

24. An exposure control apparatus according to claim 22, wherein said determining means includes an allowable shake amount calculating circuit for calculating an allowable amount of shaking from a focus distance of a lens and information of said exposure time, a comparator for comparing said allowable amount of shaking with said predicted amount of shaking from said prediction means, and a circuit for outputting a shutter-open enable signal when said predicted amount of shaking is detected to be equal to or small than said allowable amount of shaking in said comparator.

25. A shake amount predicting apparatus for detecting an amount of shaking of a camera in response to a release signal from a release operation member, and predicting an amount of shaking in an exposure time from said detected amount of shaking in a case where an exposing operation is started after a predetermined period of time, comprising:

exposure time calculating means for acquiring an exposure time based on at least a brightness of an object to be picked up and a sensitivity of a film;

detecting means for detecting an amount of shaking of said camera at least twice in a predetermined detection interval;

processing means for processing said amount of shaking detected by said detecting means based on said exposure time;

storage means capable of storing a value processed by said processing means; and

prediction means for predicting an amount of shaking in said exposure time from a value currently processed in said processing means and a previously processed value stored in said storage means in a case where said exposing operation is started after a predetermined period of time.

26. A shake amount predicting apparatus according to claim 25, wherein said processing means performs a computation given below:

m.times.S/.DELTA.t

where m is said amount of shaking detected by said detecting means, s is said exposure time information from said output means, and it is said shake detection interval in said detecting means.

27. A shake amount predicting apparatus according to claim 25, wherein said prediction means predicts said amount of shaking by a fuzz prediction.

28. A shake amount predicting apparatus for detecting an amount of shaking of a camera in response to a release signal from a release operation member, and predicting an amount of shaking in an exposure time from said detected amount of shaking in a case where an exposing operation is started after a predetermined period of time, comprising:

exposure time calculating means for acquiring an exposure time based on at least a brightness of an object to be picked up and a sensitivity of a film;

detecting means for detecting an amount of shaking of said camera at least twice in a predetermined detection interval;

storage means capable of storing a value detected by said detecting means; and

prediction means for predicting an amount of shaking in said exposure time from a value currently detected by said detecting means and a previously detected value stored in said storage means in a case where said exposing operation is started after said predetermined period of time.

29. A shake amount predicting apparatus according to claim 28, wherein said prediction means predicts said amount of shaking by a fuzzy prediction.

30. An exposure control apparatus for a camera, comprising:

shake amount detecting means for detecting an amount of shaking of said camera at sampling time intervals;

shutter release signal generating means for generating a shutter release signal for commanding an exposing operation to a film loaded in said camera;

minimum value storage means for storing a minimum value of said amount of shaking output from said shake amount detecting means;

allowable shake amount determining means for determining a maximum allowable amount of shaking based on said minimum value of said amount of shaking stored in said minimum value storage means; and

shutter-open enable signal generating means for comparing an output of said shake amount detecting means with an output of said allowable shake amount determining means after said shutter release signal generating means generates said shutter release signal, and outputting a shutter-open enable signal when a result of comparison indicates a predetermined relationship between said output of said shake amount detecting means and said output of said allowable shake amount determining means.

31. An exposure control apparatus according to claim 30, wherein said allowable shake amount determining means determines said maximum allowable amount of shaking by multiplying said a minimum value of said amount of shaking.

32. An exposure control apparatus for detecting an amount of shaking of a camera, obtaining a timing at which an influence of shaking on film exposure decreases, in accordance with said detected amount of shaking, and starting an exposing operation at said timing, comprising:

exposure time determining means for determining an exposure time to a film loaded in said camera by pre-setting or calculation;

detecting means for detecting repeatedly an amount of shaking of said camera at predetermined detection intervals;

storage means capable of storing data of said amount of shaking detected by said detecting means;

prediction means for predicting an amount of shaking occurring in said exposure time in a case where said exposing operation is started after a predetermined period of time, in accordance with a value currently detected by said detecting means and a previously detected value stored in said storage means; and

determining means for determining whether or not said exposing operation should be started after said predetermined period of time in accordance with an output of said prediction means.

33. A shake amount predicting apparatus for detecting an amount of shaking of a camera and predicting an amount of shaking occurring in an exposure time in a case where an exposing operation is started after a predetermined period of time, in accordance with said detected amount of shaking, comprising:

exposure time determining means for determining an exposure time to a film loaded in said camera by pre-setting or calculation;

detecting means for detecting an amount of shaking of said camera at least twice at predetermined detection intervals;

processing means for processing repeatedly said amount of shaking detected by said detecting means based on said exposure time;

storage means capable of storing a value output from said processing means; and

prediction means for predicting an amount of shaking occurring in said exposure time in a case where said exposing operation is started after a predetermined period of time, in accordance with a value currently processed in said processing means and a previously processed value stored in said storage means.

34. A shake amount predicting apparatus for detecting an amount of shaking of a camera, and predicting an amount of shaking occurring in an exposure time in a case where an exposing operation is started after a predetermined period of time, in accordance with a detected amount of shaking, comprising:

detecting means for detecting an amount of shaking of said camera at least twice at predetermined detection intervals;

storage means capable of storing a value detected by said detecting means; and

prediction means for predicting an amount of shaking occurring in said exposure time in accordance with a value currently detected by said detecting means and a previously detected value stored in said storage means in a case where said exposing operation is started after said predetermined period of time.

35. An exposure control apparatus for a camera, comprising:

shake amount detecting means for detecting repeatedly an amount of shaking of said camera at sampling time intervals;

a first release signal generating means for generating a first release signal for commanding a photographing preparation operation;

a second release signal generating means for generating a second release signal for commanding an exposing operation to a film loaded in said camera;

allowable shake amount determining means for detecting a maximum allowable amount of shaking after the generation of said first release signal after said first release signal generating means generates said first release signal and before said second release signal generating means generates said second release signal in accordance with said amount of shaking detected by said shake amount detecting means; and

shutter-open enable signal generating means for comparing an output of said shake amount detecting means with an output of said allowable shake amount determining means after said second release signal generating means generates a second release signal, and outputting a shutter-open enable signal when a result of comparison indicates a predetermined relationship between said output of said shake amount detecting means and said output of said allowable shake amount determining means.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a camera apparatus and, more particularly to an exposure control apparatus with shake countermeasure to easily reduce disturbance of hand shaking on an image to be picked up.

2. Description of the Related Art

There has been proposed a technique to permit a shutter release at the peak of hand shaking (where the camera displacement is smallest) in view of hand shaking considered as a simple harmonic motion, thereby minimizing the influence of the shaking of a hand holding a camera on an image to be picked up (hereinafter referred to as "pickup image").

As one example of such a technique, a technique of finding the peak of shaking using a phase shift filter is disclosed in Japanese Unexamined Patent Publication No. 63-53531.

Japanese Unexamined patent Publication No. 64-86122 discloses a technique of substituting a measured shake value into an equation for a simple harmonic motion to acquire a coefficient in order to detect the timing of the next peak of the shaking.

As discussed above, the prior art detects the peak shaking, considering the hand shaking as a simple harmonic motion.

Actually, however, hand shaking is not a simple harmonic motion, but more complicated movement, thus making approximation with simple harmonic motion difficult.

Further, unless there is a minimum measuring time for a half the period between peaks, the next peak cannot be detected, increasing a time lag for shutter release. That is, assuming the frequency of shaking is 2 Hz, the shortest time to detect the next peak is 0.5 sec after the beginning of the measuring.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a new and improved exposure control apparatus for a camera with a shake countermeasure which can cope with a complicated shaking movement even with a simple structure, and can shorten a time lag involved in the detection of shaking, thereby minimizing the influence of the shaking on a pickup image.

According to one aspect of the present invention, there is provided an exposure control apparatus comprising shake amount detecting means for repeatedly detecting shaking of a camera in a sampling time interval shorter than a hand shaking cycle; exposure calculating means for calculating a shutter speed concerning an opening of a shutter of the camera based on a sensitivity of a film to be loaded in the camera and brightness information of an object to be picked up by the camera; data processing means for acquiring processed data from a product of the shutter speed calculated by the exposure calculating means and an amount of shaking detected by the shake amount detecting means every time the amount of shaking is detected by the shake amount detecting means; storage means for storing the processed data output from the data processing means; shake amount predicting means for receiving the processed data from the data processing means and the processed data stored in the storage means to predict a total amount of shaking while the shutter is open, every time the processed data is output from the data processing means; a release switch for preparing for beginning of an exposing operation on the film; shutter enable discriminating means for discriminating permission of shutter release when a latest predicted total amount of shaking during shutter opening, output from the shake amount predicting means, is equal to or smaller than a predetermined amount, every time the release switch is operated and the shake amount predicting means predicts the total amount of shaking; and shutter control means for starting opening the shutter based on a signal from the shutter enable discriminating means and controlling an exposure time based on the shutter speed calculated by the exposure calculating means.

With the above structure, an exposing operation can start in a shaking state that does not affect image pickup, making it possible to reduce the influence of shaking on a pickup image within an allowable range.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention ma be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

FIG. 1 is a diagram illustrating the basic structure of an exposure control apparatus for a camera according to one embodiment of the present invention;

FIGS. 2A and 2B are monitor waveform diagrams in case of bad shaking;

FIGS. 3A and 3B are monitor waveform diagrams in case of little shaking;

FIG. 4 is a diagram showing an example of shaking as a displacement in one direction for the sake of convenience;

FIG. 5 is a detailed block diagram of the structure in FIG. 1;

FIGS. 6A and 6B are diagrams exemplifying a pupil position detector;

FIG. 7 is a diagram illustrating the result of analysis of the frequency component of shaking based on the amount of shaking;

FIG. 8 is a waveform diagram of a shaking output shown for explaining the computation to acquire a predicted amount of shaking;

FIGS. 9A to 9F are diagrams illustrating specific examples of acquiring the predicted amount of shaking;

FIGS. 10A and 10B are diagrams illustrating examples of a membership function for acquiring a predicted amount of shaking using a fuzzy prediction;

FIG. 11 is a diagram exemplifying prediction rules by the MIN-MAX-center-of-gravity method in the case where a predicted amount of shaking is acquired using a fuzzy prediction;

FIG. 12 is a diagram showing prediction procedures in the case where a predicted amount of shaking is acquired using a fuzzy prediction;

FIG. 13 is a diagram for explaining how to acquire a predicted amount of shaking by linear approximation;

FIG. 14 is a diagram showing the relationship between the shutter speed and the maximum wait time for discriminating shutter permission;

FIG. 15 is a block diagram showing an example of realizing the embodiment in FIG. 1 using a CPU;

FIG. 16 is a flowchart showing the case where the structure shown in the block diagram in FIG. 15 is realized by using a CPU;

FIG. 17 is a flowchart illustrating a release sequence of a lens shutter camera;

FIG. 18 is a flowchart illustrating a subroutine for evaluation of the amount of shaking along the block diagram in FIG. 5;

FIG. 19 is a diagram showing a ROM table for a variable S of the shutter speed and processed data SK;

FIG. 20 is a flowchart illustrating a second embodiment of evaluation of the amount of shaking;

FIG. 21 is a flowchart illustrating a third embodiment of evaluation of the amount of shaking;

FIG. 22 is a diagram of a simple table showing the relationship between the shutter speed and the allowable amount of shaking;

FIG. 23 is a diagram of a table showing the relationship between the shutter speed and the allowable amount of shaking, the latter varying gently with a change in the former;

FIG. 24 is a block diagram illustrating another structure of a shutter enable discriminating section;

FIG. 25 is a diagram showing the relationship between a focus distance used to determine an allowable amount of shaking and a shutter speed with respect to the allowable amount of shaking;

FIG. 26 is a flowchart in the case where the structure in FIG. 24 is realized using a CPU;

FIG. 27 is a flowchart in the case where the flow in FIG. 26 is realized simply;

FIG. 28 is a structural diagram of essential portions illustrating an embodiment to predict the amount of shaking based on three inputs by a fuzzy prediction; and

FIG. 29 is a structural diagram of a shake evaluation section realized by hardware.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first preferred embodiment of the present invention will now be described referring to the accompanying drawings.

FIG. 1 illustrates the basic conception of an exposure control apparatus for a camera according to the present invention.

The exposure control apparatus comprises a shake amount detecting section 1, a shutter-speed determining section 2, a data processing section 3, a storage section 4, a shake amount calculating section 5, a shutter enable discriminating section 6 and a reference time generator 7. The shake amount detecting section 1 detects the amount of shaking caused by hand-shaking of a user. The shutter-speed determining section 2 determines the shutter speed (exposure time) from the result of metering light, or the like. The data processing section 3 processes the amount of shaking detected by the shake amount detecting section 1 based on the shutter speed determined by the shutter-speed determining section 2. The storage section 4 stores shake data (shake compensation value) processed in the data processing section 3. The shake amount calculating section 5 predicts the total amount of shaking during opening a shutter-open period, based on the current shake data and the previous shake data stored in the storage section 4. The shutter enable discriminating section 6 discriminates if the shutter should be opened, based on the amount of shaking predicted by the shake amount calculating section 5 and the shutter speed by the shutter-speed determining section 2. The reference time generator 7 controls the operation timings of the shake amount determining section 1, the storage section 4 and the shake amount calculating section 5.

The exposure control apparatus for a camera is designed to predict the total amount of shaking during exposure based on the current and previous shake data acquired by processing the amount of shaking with the shutter speed, and to permit the shutter to open in association with the shutter speed if the amount of shaking is allowable, and does not affect an image to be picked up.

The shaking will now be described with a specific example, hand shaking.

FIGS. 2A and 2B, and 3A and 3B show typical examples when actual hand shaking is monitored.

The actual amount of shaking on the surface of a film is shown in each graph with the focus distance f of a lens as 100 mm.

FIGS. 2A and 2B each exemplify a relatively large amount of shaking. FIG. 2A shows a shake in x and y directions to the time axis, while FIG. 2B shows the locus of the shake on the x-y plane.

FIGS. 3A and 3B each exemplify a small amount of shaking by a careful shutter release. Like FIGS. 2A and 2B, FIG. 3A shows a shake in x and y directions to the time axis, while FIG. 3B shows the locus of the shake on the x-y plane.

As apparent from these graphs which simply represent examples, there is no regular change but a random movement (irregular change) in hand shaking. It is therefore obvious that the shaking cannot be approximated by a simple harmonic motion.

FIG. 4 is a diagram showing an example of shaking as a displacement in one direction for the sake of convenience. A description will be given of one way to reduce the influence of a shake on a pickup image, referring to FIG. 4.

With the shutter speed of 1/125, the opening time of the shutter is 8 ms. Assuming that an allowable amount of shaking is 30 .mu.m, it is understood that the shutter can be released at any timing. In other words, since the change in shake does not exceed 30 .mu.m while the shutter is to open, the shutter can be released at any timing.

With the shutter speed set to 1/30, however, the shutter opening time is about 33 ms. During this time, the shake change is smaller than 30 .mu.m in the ranges A.sub.1 and A.sub.2, for example. The shutter release timing is therefore limited.

Likewise, with the shutter speed of 1/60, the shutter can be released in a wider range than A.sub.1 and A.sub.2. With the shutter speed of 1/15, the range for the shutter release is narrower, so that the shake change may never become smaller than 30 .mu.m, i.e., the shutter release timing may never come.

It is therefore apparent that the timing for opening the shutter should be decided in association with the shutter speed, and that the shutter can be released in a range, such as A.sub.1, where the shake change is relatively stable without even waiting for the peak of the shake to come in order to reduce the influence by the shake.

When the shutter speed is high, of course, the shutter can be released at a point where the change in shake is relatively large.

The first embodiment will be further described in detail, with this theory as the premise.

In FIG. 5, the shake amount detecting section 1 includes a pupil position detector 1a, a first storage section 1b and a subtracter 1c. The pupil position detector 1a detects, for example, the position of the pupil in accordance with a timing signal from the reference time generator 7 to be described later, and calculates a relative position from a camera. The first storage section 1b stores the detection output of the pupil position (shake output) from the pupil position detector la in synchronism with the timing signal. The subtracter 1c calculates the difference between the previous shake output stored in the first storage section 1b and the current shake output from the pupil position detector 1a, i.e., acquires the amount of shaking, m.

The shutter-speed determining section 2 includes a light metering section 2b which meters lights, and an exposure calculating section 2c which calculates exposure based on the DX code from the DX reader 2a and a metered light value from the light metering section 2b to determine a shutter speed S.

A release switch SW11 outputs the first (1st) release signal by half depression, and the second (2nd) release signal by full depression.

A zoom position detector 12 detects a focus distance f for a zoom lens.

A hand-shaking alarm section 13 determines if hand shaking has occurred, based on the shutter speed S from the shutter-speed determining section 2 and the focus distance f detected by the zoom position detector 12, and informs the user of the judgment at the timing when the 1st release signal is sent from the release SW11. If the shutter speed S is greater than 1/f, the reciprocal of the focus distance f (1/f<S), the hand-shaking alarm section 13 normally generates a tone or lights a light-emitting diode in a finder to instruct a careful shutter release.

A shutter timing generator 14 receives the 2nd release signal from the release SW11, and generates a shutter-open signal in the normal sequence which does not considerate the hand shaking.

Based on the amount of shaking, m, from the shake amount detector 1 and the shutter speed S from the shutter speed determining section 2, the data processing section 3 calculates "m.times.S/.DELTA.t." The amount of shaking per unit time