(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.