Camera with automatic focus and exposure control means

We claim:

1. A camera with an automatic focus and exposure (AF and AE) control means, comprising:

means for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition;

means for selecting either a first operation mode or a second operation mode;

means, operatively connected to said detecting means and said selecting means, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objective lens is established, the operation of the focusing means being interrupted after the in-focus condition has once been established when the first operation mode is selected, and the operation of the focusing means being repeated in accordance with the focusing signal even if an out-of-focus condition is detected again after the in-focus condition has once been established when the second operation mode is selected;

first light measurement means for measuring light from a first measuring area corresponding to a focus detection area to produce a first light measuring signal indicative of an intensity of light measured, the light from the focus detection are being received by the detecting means for detecting the focusing condition of the objective lens;

second light measurement means for measuring light coming from a second measuring area larger than the first measuring area to produce a second light measurng signal indicative of an intensity of light measured; and

exposure control means, operatively connected to said first and second light measurement means, said selecting means and said focusing means, for controlling exposure amount on the basis of the first light measuring signal produced when the in-focus signal is produced in the condition in which the first operating mode is selected, and for controlling exposure amount on the basis of the second light measuring signal independently of the in-focus signal in the condition in which the second operation mode is selected.

2. A camera according to claim 1, wherein said selecting means includes an AF mode selection switch in which a switched state gives a first operation mode and another switched state gives a second operation mode.

3. A camera according to claim 1, wherein said first operation mode is a spot metering mode and said second operation mode is an average light measurement mode, and wherein said first light measurement means comprises a spot metering sensor and said second light measurement means comprises an averaged light measurement sensor.

4. A camera according to claim 1, further comprising a shutter release button providing a signal for initiating said focusing means and said exposure control means when said shutter release button is pushed down at a first stage, and also providing another signal for energizing said exposure control means to actually take a picture when said shutter release button is pushed down at a second stage.

5. A camera according to claim 1, wherein said AF and AE control means further comprises an AF display controlled by said detecting means and including a first indicator lit when said objective lens is in an in-focus condition, a second indicator lit when said objective lens is in a front focus condition away from said in-focus condition, and a third indicator lit when said objective lens unit is in a rear focus position away from said in-focus condition, both said second and third indicators being illuminated when the detecting means cannot detect the focusing condition of the objective lens.

6. A camera according to claim 1, wherein said AF and AE means further comprises an AE display controlled by said exposure control means and displaying the exposure control data from said exposure control means.

7. A camera according to claim 1, wherein said exposure control means, includes means for storing said first light measuring signal when said in-focus signal is produced in said first operation mode, said exposure being determined by data from said storing means.

8. A camera according to claim 7, where storing means includes a sample holder which holds said first light measuring signal when said in-focus signal is produced.

9. A camera according to claim 7, wherein storing means includes a latch circuit which latches said first light measuring signal when said in-focus signal is produced.

10. A camera according to claim 1, wherein said exposure control means, includes means for storing said first or second light measuring signal when said in-focus signal is produced, said exposure being determined by data from said storing means.

11. A camera with an automatic focus and exposure (AF and AE) control means, comprising:

means for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition;

means, operatively connected to said detecting means, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objective lens is established, the operation of the focusing means being repeated in accordance with the focusing signal even if an out-of-focus condition is established again after the in-focus condition has once been detected;

first light measurement means for measuring light coming from a first measuring area corresponding to a focus detection area to produce a first light measuring signal indicative of an intensity of light measured, the light from the focus detecting area being received by the detecting means for detecting the focusing condition of the objective lens;

second light measurement means for measuring light coming from a second measuring area larger than the first measuring area to produce a second light maasuring signal indicative of an intensity of light measured; and

exposure control means, operatively connected to said first and second light measurement means and said focusing means, for controlling exposure amount on the basis of the first light measuring signal when the in-focus signal is produced at a time of starting the exposure control operation, and for controlling exposure amount on the basis of the second light measuring signal when the in-focus signal is not produced at a time of starting the exposure control operation.

12. A camera according to claim 11, further comprising a shutter release button providing a signal for initiating said focusing means and said exposure control means when said shutter release button is pushed down to a first stage, and providing another signal for energizing said exposure control means to actually take a picture when said shutter release button is pushed down to a second stage.

13. A camera according to claim 11, wherein said AF and AE means further comprises an AF display controlled by said detcting means and including a first indicator lit when said objective lens is in an in-focus condition, a second indicator lit when said objective lens is in front-focus condition away from said in-focus condition, and a third indicator lit when said objective lens is in rear-focus position away from said in-focus condition, both said second and third indicators being illuminated when the detecting means cannot detect the focusing condition of the objective lens.

14. A camera according to claim 11, wherein said AF and AE means further comprises an AE display illuminated by said exposure control means, and displaying the exposure control data from said exposure control means.

15. A camera according to claim 11, wherein said first light measurement means comprises a spot metering sensor and said second light measurement means comprises an averaged light measurement sensor.

16. A camera according to claim 11, wherein said exposure control means includes means for storing said first light measuring signal when said in-focus signal is produced, said exposure being determined by data from said storing means.

17. A camera according to claim 16, wherein said storing means includes a sample holder which holds said first light measuring signal when said in-focus signal is produced.

18. A camera according to claim 16, wherein said storing means includes a latch circuit which latches said first light measuring signal when said in-focus signal is produced.

19. A camera according to claim 11, wherein said exposure control menas includes means for storing said first or second light measuring signal when said in-focus signal is produced, said exposure being determined by data from said storing means.

20. A camera according to claim 11, further comprising means for setting an initial condition for selecting data used for calculating said exposure, of either said first or second light measuring signal.

21. A camera with an automatic focus and expsoure (AF and AE) control means, comprising:

means for detecting a direction of defocus of an objective lens and amount of defocus thereof with respect to a predetermined focal plane;

means, operatively connected to said detecting means, for focusing the objective lens in accordance with the detected direction of defocus and the detected amount of defocus to stop the focusing of the objective lens and to produce an in-focus signal when the detected amount of defocus becomes smaller than a predetermined first amount;

first light measurement means for measuring light coming from a first measuring area corresponding to a focus detection area to produce a first light measuring signal indicative of an intensity of light measured, the light from the focus detection area being received by the detecting means for detecting the direction of defocus and the amount of defocus of the objective lens;

second light measurement means for measuring light coming from a second measuring area larger than the first measuring area to produce a second light measuring signal indicative of an intensity of light measured; and

exposure control means, operatively connected to said first and second light measurement means, and said focusing means, for controlling exposure amount on the basis of the first light measuring signal when the in-focus signal is produced at a time of starting the exposure control operation, and for controlling exposure amount on the basis of the second light measuring signal when the in-focus signal is not produced at a time of starting the exposure control operation.

22. A camera according to claim 21, wherein said focusing means produces a semi in-focus signal when the detected amount of defocus becomes smaller than a predetermined second amount which is determined as being large than said predetermined first amount, and wherein said exposure control means controls exposure amount on the basis of said first light measuring signal when said semi in-focus signal is produced at a time of starting the exposure control operation.

23. A camera according to claim 21, comprising a shutter release button providing a signal for initiating said focus means and said exposure control means when said shutter release button is pushed down to a first stage, and also providing another signal for energizing said exposure control means to acutally take a picture when said shutter release button is pushed down to a second stage.

24. A camera according to claim 21, wherein said AF and AE means further comprises an AF display controlled by said detecting means and including a first indicator lit when said objective lens is in an in-focus condition, a second indicator lit when said objective lens is in a front-focus condition away from said in-focus condition, and a third indicator lit when said objective lens is in a rear-focus position away from said in-focus position, both said second and third indicators being illuminated when the detecting means cannot detect the direction of defocus and the amount thereof.

25. A camera according to claim 21, wherein said AF and AE means further comprises an AE display illuminated by said exposure control means, and displaying exposure control data from said exposure control means.

26. A camera according to claim 21, wherein said first light measurement means comprises a spot metering sensor and said second light measurement means comprises an averaged light measurement sensor.

27. A camera according to claim 21, wherein said exposure control means, includes means for storing said first light measuring signal when said in-focus signal is produced, said exposure being determined by data from said storing means.

28. A camera according to claim 27, wherein said storing means includes a sample holder which holds said first light measuring signal when said semi in-focus signal is produced.

29. A camera according to claim 27, wherein said storing means includes a latch circuit which latches said first light measuring signal when said semi-in-focus signal is produced.

30. A camera according to claim 21, wherein said exposure control means, includes means for storing said first or second light measuring signal when said semi-in-focus signal is produced, said exposure being determined by data from said storing means.

31. A camera according to claim 21, further comprising means for setting an intial condition for selecting data, used for claculating said exposure, of either said first or second light measuring signal.

32. A camera with an automatic focus and exposure (AF and AE) control means, comprising:

means for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition;

means, operatively connected to said detecting means, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objecitve lens is established, the operation of the focusing means being repeated in accordance with the focusing signal even if an out-of-focus condition is detected again after the in-focus condition has once been detected;

light measurement means for repeatedly measuring light coming from a measuring area corresponding to a focus detection area to repeatedly produce a light measuring signal indicative of an intensity of light measured, the light from which is received by the detecting means for detecting the focusing condition of the objective lens;

means for updating said light measuring signal while said in-focus signal is produced and for storing a last light measuring signal when said in-focus signal is not produced; and

means, operatively connected to said update and storing means, for controlling exposure amount on the basis of said stored light measuring signal.

33. A camera according to claim 32, further comprising a shutter release button providing a signal for initiating said focusing means and said exposure control means when said shutter release button is pushed down to a first stage, and providing another signal for energizing said exposure control means to actually take a picture when said shutter release button is pushed down to a second stage.

34. A camera according to claim 32, wherein said AF and AE means further comprises an AF display controlled by said detecting means and including a first indicator lit when said objecitve lens is in an in-focus condition, a second indicator lit when said objective lens is in a front-focus condition away from said in-focus condition, and a third indicator lit when said condition lens is in a rear-focus condition away from said in-focus condition, both said second and third indicators being illuminated when the detecting means cannot detect the focusing condition of the objective lens.

35. A camera according to claim 32, wherein said AF and AE means further comprises an AE display controlled by said exposure control means, and displaying exposure control data from said exposure control means.

36. A camera according to claim 32, wherein said light measurement means comprises a spot metering sensor.

37. A camera according to claim 32, wherein said exposure control means includes means for storing said light measuring signal when said in-focus signal is produced, or updating said light measuring signal, said exposure being determined by data from, said storing means.

38. A camera according to claim 37, wherein said storing means stores data of said light measuring signal after a predetermined time has elapsed from a time the in-focus signal is produced, said predetermined time being a response time of said detecting means, said focusing means and said light measurement means.

39. A camera according to claim 38, wherein said storing means includes a sample holder which holds said light measuring signal when said in-focus signal is produced.

40. A camera according to claim 38, wherein said storing means includes a latch circuit which latches said light measuring signal when said in-focus signal is produced.

41. A camera according to claim 32, wherein said exposure control means, further operatively connected to said detecting means, includes means for storing said light measuring signal when said in-focus signal is produced, said exposure being determined by data from said storing means.

42. A camera according to claim 41, wherein said storing means stores data of said light measuring signal after a predetermined time has elapsed from a time at which said in-focus signal is produced, said predetermined time being a response time of said detecting means, said focusing means and said light measurement means.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a camera. More particularly, it relates to a camera with automatic focus and exposure (AF and AE) control means and improved operability and exposure performance.

(2) Description of the Related Arts

Cameras with AF and AE control means are extensively known.

Japanese Unexamined Utility Model Publication No. 53-148638, entitled "a control apparatus of a camera" and published on Nov. 12, 1978, discloses a camera in which light-measured data is stored in a memory immediately before a mirror-up operation is effected in a one-shot AF mode wherein the exposure is controlled on the basis of spot metering (spot light measuring) data. The AF operation is stopped when an objective lens (or taking lens) reaches an in-focus position defined by the relationship between a focus position of the lens and a position of an object to be photographed against the lens. Simultaneously, the spot metering data is stored in another memory by activating a switch other than that for storing the above light-measured data. Upon operation of the shutter release, the exposure control is effected on the basis of the stored spot metering data. In this camera, the exposure can be controlled with the spot metering data or with the averaged light measuring data, and thus, the exposure control may be effected on the basis of the latest light-measured data, either the spot metering data or the averaged light measuring data, at a time immediately before the shutter release operation after the focusing operation of the object lens is completed.

However, the above camera does not have a continuous AF function as provided in the present invention, but has a feature wherein the AF operation is restarted if the lens moves out of the in-focus position after the lens was once fixed (locked) at the in-focus position. In this case, the previous in-focus operation must be released and a new in-focus operation carried out. Accordingly, the above camera has disadvantages involving manual operability and speed.

Japanese Unexamined Patent Publication No. 58-120225, entitled "camera" and published on July 18, 1983, discloses a camera having a one-shot AF mode and a servo AF mode. In the one-shot AF mode, the exposure control is effected on the basis of the averaged light-measuring data stored in a memory by the shutter release operation after fixing the lens at the in-focus position. In the servo AF mode, the exposure control is effected on the basis of the spot metering data. Upon pushing down the release button to a first stage, the lens is fixed regardless of whether the lens is in or out of the in-focus position, and the spot metering data is stored. The exposure control is effected on the basis of the stored spot metering data when the release button is pushed down to a second stage. Namely, the averaged light-measuring data in the one-shot AF mode and the spot metering data in the servo AF mode are unconditionally used

This type of camera has the disadvantages of insufficient exposure control and low operability. In the one-shot AF mode, the spot metering data against a main object to be photographed may not provide sufficient exposure. On the other hand, in the servo AF mode, when the main object, for example, a moving car, moves out the spot metering area after the averaged light-measuring data has been stored, a large illuminance (brightness) difference between the stored data used for calculating the exposure and a current light data may exist, and accordingly, the picture taken may be insufficiently exposed.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a camera having an AF and AE control means by which the operability for a stationary object and a moving object is improved.

Another object of the present invention is to provide a camera having an AF and AE control means whereby the exposure for a moving object is improved.

Still another object of the present invention is to provide a camera having an AF and AE control means whereby the exposure for a moving object is further improved together an improved operability.

Yet another object of the present invention is to provide a camera having an AF and AE control means whereby the exposure for a moving object is further improved even if the release operation is executed in a transition time in which the light measurement data is changing.

According to a first aspect of the present invention, there is provided a camera with an automatic focus and exposure (AF and AE) control means, including: a unit for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition; a unit for selecting either a first operation mode or a second operation mode; and a unit, operatively connected to the detecting unit and the selecting unit, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objective lens is detected by the detecting unit. The operation of the focusing unit is interrupted after the in-focus condition has once been detected when the first operation mode is selected, while the operation of the focusing unit is repeated in accordance with the focusing signal even if an out-of-focus condition is detected again after the in-focus condition has once been detected when the second operation mode is selected. The camera also includes a first light measurement unit for measuring light coming from a first measuring area, the light from which is received by the detecting unit for detecting the focusing condition of the objective lens to produce a first light measuring signal indicative of the intensity of light measured; a second light measurement unit for measuring light coming from a second measuring area larger than the first measuring area to produce a second light measuring signal indicative of the intensity of light measured; and an exposure control unit, operatively connected to the first and second light measurement units, the selecting unit and the focusing unit, for controlling exposure amount on the basis of the first light measuring signal produced when the in-focus signal is produced in the condition in which the first operation mode is selected, and for controlling exposure amount on the basis of the second light measuring signal independently of the in-focus signal in the condition in which the second operation mode is selected.

In the first operation mode, the first light measured data is latched when the focusing of the lens is achieved, and the exposure control is effected by using the same. In the second operation mode, the exposure control is effected by using the second light measured data.

The manual operations for AE mode change and AE lock are omitted.

According to a second aspect of the present invention, there is also provided a camera with an automatic focus and exposure (AF and AE) control means, including: a unit for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition; a unit, operatively connected to the detecting unit, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objective lens is detected by the detecting unit, the operation of the focusing unit being repeated in accordance with the focusing signal even if an out-of-focus condition is detected again after the in-focus condition has once been detected; a first light measurement unit for measuring light coming from a first measuring area, the light from which is received by the detecting unit for detecting the focusing condition of the objective lens to produce a first light measuring signal indicative of the intensity of light measured; a second light measurement unit for measuring light coming from a second measuring area larger than the first measuring area to produce a second light measuring signal indicative of intensity of light measured; and an exposure control unit, operatively connected to the first and second light measurement units and the focusing unit, for controlling exposure amount on the basis of the first light measuring signal when the in-focus signal is produced at a time of starting the exposure control operation, and for controlling exposure amount on the basis of the second light measuring signal when the in-focus signal is not produced at a time of starting the exposure control operation.

In the first operation mode, the first light measured data is latched when the focusing of the lens is achieved, and the exposure control is effected by using the same. In the second operation mode, the exposure control is effected by using the first light measured data when the focusing of the lens is achieved, or the second light measured data at any other time.

According to a third aspect of the present invention, there is provided a camera with an automatic focus and exposure (AF and AE) control means, including: a unit for detecting a direction of defocus of an objective lens and amount of defocus thereof with respect to a predetermined focal plane; a unit operatively connected to the detecting unit, for focusing the objective lens in accordance with the detected direction of defocus and the detected amount of defocus to stop the focusing of the objective lens when the detected amount of defocus becomes smaller than a predeterminded first amount; a first light measurement unit for measuring light coming from a first measuring area, the light from which is received by the detecting unit for detecting the direction of defocus and the amount of defocus of the objective lens to produce a first light measuring signal indicative of the intensity of light measured; a second light measurement unit for measuring light coming from a second measuring area larger than the first measuring area to produce a second light measuring signal indicative of the intensity of light measured; and an exposure control unit, operatively connected to the first and second light measurement units and the focusing unit, for controlling exposure amount on the basis of the first light measuring signal when the in-focus signal is produced at a time of starting the exposure control operation, and for controlling exposure amount on the basis of the second light measuring signal when the in-focus signal is not produced at a time of starting the exposure control operation.

Preferably, the focusing unit produces a semi in-focus signal when the detected amount of defocus becomes smaller than a predetermined second amount which is determined as being larger than the predetermined first amount. The exposure control unit controls exposure amount on the basis of the first light measuring signal when the semi in-focus signal is produced at a time of starting the exposure control operation.

According to the present invention, there is provided a camera with an AF and AE control structure including: a unit for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition; a unit, operatively connected to the detecting unit, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objective lens is detected by the detecting unit, the operation of the focusing unit being repeated in accordance with the focusing signal even if an out-of-focus condition is detected again after the in-focus condition has once been detected; a light measurement unit for repeatedly measuring light coming from a measuring area, the light frmm which is received by the detecting unit for detecting the focusing condition of the objective lens to repeatedly produce a light measuring signal indicative of the intensity of light measured; a unit for updating said light measuring signal while the in-focus signal is being produced and for holding a last light measuring signal just until the in-focus signal is produced; and a unit, operatively connected to the update and holding unit, for controlling exposure amount on the basis of said held light measuring signal.

According to the present invention, there is also provided a camera including: a unit for detecting a focusing condition of an objective lens attached to the camera to produce a focusing signal indicative of the detected focusing condition; a unit, operatively connected to the detecting unit, for focusing the objective lens in accordance with the focusing signal to produce an in-focus signal when the in-focus condition of the objective lens is detected by the detecting unit; a first light measurement unit for measuring light on an area corresponding to a region of an object to be detected at said detecting unit; a second light measurement unit for measuring light on another area broader than the first area; a unit, operatively connected to the first and second light measurement units and the focusing unit, for controlling exposure amount. The exposure contool unit determines the exposure amount on the basis of a first data from the first light measurement unit, or a second data from the second light measurement unit when the in-focus signal is produced.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and features of the present invention will be clearly understood with reference to the accompanying drawings, in which:

FIGS. 1a and 1b are views representing framing on stationary main objects;

FIG. 2 is a block chart showing the prior art AF and AE operation;

FIGS. 3a and 3b are views representing framing on a moving main object;

FIG. 4 is a block diagram of a first conceptual embodiment of a camera including the AF and AE control means in accordance with the present invention;

FIG. 5 is a block chart showing the operation of the AF and AE control means shown in FIG. 4;

FIG. 6 is a circuit diagram of a first concrete embodiment of the camera shown in FIG. 4;

FIGS. 7a and 7b are timing charts showing the operation of the circuit in FIG. 6;

FIG. 8 is another circuit diagram of a second concrete embodiment of the camera in FIG. 4;

FIG. 9 is a block diagram of a second conceptual embodiment of a camera including the AF and AE control means in accordance with the present invention;

FIGS. 10a, 10b, and 10c are timing charts showing the operation of the AF and AE control means shown in FIG. 9;

FIGS. 11, 12, and 13 are circuit diagrams of first, second, and third embodiments of the camera shown in FIG. 9;

FIGS. 14a and 14b are timing charts for the circuits shown in FIGS. 11 to 13;

FIG. 15 is a block diagram of a third conceptual embodiment of a camera having the AF and AE control means in accordance with the present invention;

FIGS. 16a, 16b, and 16c are timing charts illustrating the operation of the AF and AE control means shown in FIG. 15;

FIGS. 17 and 18 are circuit diagrams of first and second specific embodiments of the circuit shown in FIG. 15;

FIGS. 19a, 19b, and 19c are timing charts showing the operation of the circuits shown in FIGS. 17 and 18;

FIG. 20 is a circuit diagram of a third specific embodiment of the circuit shown in FIG. 15;

FIGS. 21a to 21i are timing charts showing the operation of the circuit in FIG. 20; and

FIGS. 22, 23, and 24 are circuit diagrams of other specific embodiments of the circuit shown in FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before describing preferred embodiments of the present invention, a more specific description will be given of a primitive example of an AF type camera, for reference.

A one-shot AF mode of a primitive example of an AF type camera will be described with reference to FIGS. 1a, 1b, and FIG. 2. In FIGS. 1a and 1b, a circle spot metering area (stop light measuring area) 52 exists in a center of a finder field 51 and a rectangular focus detection sensitivity area 53 exists inside of the spot metering area 52. Below the finder field 51 are provided indicators 54, 55, and 56 displaying focus information obtained by a focus detecting unit. The indicator 54 is turned ON when an objective lens is placed in an in-focus position; the indicator 55 is turned ON when the objective lens is placed in a front-focus position; and, the indicator 56 is turned ON when the lens is placed in a rear-focus position. In the one shot AF mode, when the lens is once moved to the in-focus position, the in-focus indicator 54 is turned ON and the lighting is maintained. On the other hand, when a brightness distribution obtained in the focus detection unit is in a low contrast state, both the front-focus indicator 55 and the rear-focus indicator 56 are turned ON.

In FIGS. 1a and 1b, the main object to be photographed is almost stationary. Accordingly, the operation of the camera is performed as shown in FIG. 2, when a user takes a photograph with the framing shown in FIG. 1a. Since the main object is stationary, and thus a distance between the camera, more precisely, the lens, and the main object is almost constant, the user first sets the AF operation mode to the one shot AF mode at step S01, and then sets the AE mode to the spot metering mode at step S02. At step S03, the user adjusts the framing through the finder field 51 so that the focus detection sensitiviy area 53 and the spot metering area 52 are at the main object, as shown in FIG. 1b. This framing will be maintained until the completion of step S06. At step S04, an AF and AE start switch is made ON, starting an AF operation and an AE operation. When the AF operation is completed (step S05), the lens is fixed at a position wherein the lens is in-focus and the in-focus indicator 54 is turned ON and kept ON. The AF operation is shown to be completed by the lighting of the in-focus indicator 54. After completion of the AF operation, when an AE lock switch is turned ON (step S06), the light-measured data for the position of the focus detection sensitivity area 53 at the main object is latched. At this stage, the information for taking a photograph is established. In order to obtain the frame for the photograph at the condition as shown in FIG. 1a, the framing is effected (step S07). Subsequently, when a release switch is turned ON at step S08, a shutter of the camera is released, taking the photograph.

When the main object is stationary, the one-shot AF mode and the spot metering mode are adopted, as set forth above. However, the operation for setting the AE mode to the spot metering mode, as shown in step S02 is required when the one-shot AF mode is selected, and another operation for turning the AE lock switch ON as shown in step S06 is also required. Accordingly, more manual operations are required for taking the photograph.

Next, a primitive example of a continuous AF operation will be described with reference to FIGS. 3a and 3b. In this case, the main object is a moving object, e.g., a moving car, and thus a distance between the camera and the main object will vary from moment to moment. The continuous AF mode is set to change the position of the lens in response to the change of the distance between the camera and the object to be photographed. However, this continuous AF mode differs from a continuous AF mode of the present invention, set forth later in detail, and this difference will be understood from the description of embodiments of the present invention.

When the main object is moving it is very difficult to constantly hold the spot metering area 52 and the focus detection sensitivity area 53 in the center of the finder field 51 on the main object, as shown in FIG. 3a. As a result, the main object moves away from the spot metering area 52 and the focus detection sensitivity area 53, resulting in frequent and large fluctuations of the brightness distribution.

To alleviate these large fluctuations of the brightness distribution, an approach whereby the brightness distribution data is neglected when there is a large brightness distribution is used, and the AF adjustment operation is restarted by using a next measured brightness distribution. This approach, however, still involves a disadvantage of insufficient exposure, as set forth immediately below. When the spot metering mode is selected in the continuous AF mode, the shutter operation may be effected in a condition where the main object is not in the center of the finder field 51, and the exposure control may be performed by using another spot metering data from another object which is not the main object in question, and which may be in the background far away from the main object. When the deviation of the brightness distribution between the main object and this other object is large, a proper exposure for taking the picture cannot be obtained.

Now, embodiments of a camera to which an AF and AE control of the present invention is applied will be described with reference to the accompanying drawings.

Referring to FIGS. 4 and 5, a first conceptual embodiment of the present invention will be described. In FIG. 4, a camera includes the AF and AE control device consisting of an AF adjustment block 10a, an AE control block 20a, a spot metering unit 31 and an averaged light measuring unit 32, a lens system, a drive unit (not shown in FIG. 4) for moving an objective lens unit, including at least an objective lens, a mechanism (not shown in FIG. 4), and a control unit (not shown in FIG. 4) for controlling exposure. The AF adjustment block 10a includes a one-shot AF mode setting unit 11, a continuous AF mode setting unit 12, a lens drive unit 13, a focus detection unit 14, a unit 15 for detecting the in-focus condition and storing the same, and stopping the focus adjustment, and a focus adjustment stop unit 16. The exposure control block 20a includes an AE lock unit 21, a switching unit 22 for selecting light-measured signals, and an exposure calculation unit 23.

The AF and AE control device may be applied to a single-lens reflex camera.

First, the operation will be described when the main object is stationary as shown in FIGS. 1a and 1b.

As shown in FIG. 5, when a stationary object is to be photographed, the user of the camera selects step S11. At step S11, the one shot AF mode is selected through the one-shot AF mode setting unit 11 by a manual operation which energizes the in-focus detection and store and focus adjustment stop unit 15 and the switching unit 22 to operatively connect the spot metering unit 31 to the exposure calculation unit 23 through the AE lock unit 21 (step S12). Note that the operation at step S02 in FIG. 2 is omitted. Next, the framing is effected to place the main object in the focus detection sensitivity area 53 and the spot metering area 52 (S12). When the lens unit is moved to the in-focus position by driving the lens drive unit 13 in response to the operation of the focus detection unit 14, the motion of the lens unit is stopped by the in-focus detection and store and focus adjustment stop unit 15 and the lens drive unit 13, fixing the lens at that position. At the same time, the spot metering data to be applied to the exposure calculation unit 23 is latched at the AE lock unit 21, i.e., AE locking is effected. This AE locking is effected without making the AE lock switch ON, as described at step S06 in FIG. 2. A second framing is effected in the same way as at step S13. A release signal is then supplied to the exposure calculation unit 23, and accordingly, the exposure calculation unit 23 controls the exposure on the basis of the spot metering data latched in the AE lock unit 21.

The exposure calculation determines a combination of an aperture value of the lens and a shutter speed for suitably exposing the object on a film on the basis of a brightness of the light-measured object and a sensitivity of the film to be used. The exposure control controls an aperture of the aperture diaphram and a shutter open time.

As mentioned above, when the one-shot AF mode is selected, the light-measuring of the spot metering mode is automatically set. In addition, when the lens unit reaches the in-focus position the fixing of the lens unit at that position and the AE locking are automatically effected (step S16).

When the main object is moving as shown in FIGS. 3a and 3b, the continuous AF mode is selected by a manual operation by means of the continuous AF mode setting unit 12 (step S21), which energizes the focus adjustment stop unit 16 a