Device for determining whether focus detection may be accurately performed using characteristic data of an interchangeable lens and focus detection device

摘要

A camera having focus detection capability which decides whether or not focus detection is possible. The camera is capable of accommodating interchangeable lenses, and determines whether focus detection is possible for an optional combination of interchangeable lens and camera based upon characteristic data for the interchangeable lens and characteristic data for a focus detection device. The characteristic data for the interchangeable lens is data representing an exit beam for an optional image height which is stored in a lens memory. The data representing the exit beam may be the position and size of plural circular apertures for the interchangeable lens. The characteristic data for the focus detection device is stored in a camera body memory and represents a position and shape of a rangefinder image point. When focus detection is possible, a photographic lens is driven according to the focus detection result.