Data input/output device for a camera

Abstract

In an interchangeable lens including an optical system adjustable for focusing and adapted to be detachably mounted on a camera body which is provided with focus detection means for detecting an amount of defocus of an object image formed by the optical system, and drive means for driving the optical system for the focus adjustment thereof in accordance with the detected amount of defocus. The interchangeable lens comprises, inter alia, a code plate for producing a plurality of digital photographic distance signals representing given discrete photographic distances of the optical system in accordance with the adjustment of the optical system for focusing. Circuit means output a predetermined one of a plurality of inputs, the plurality of outputs including a plurality of conversion coefficients needed for converting the detected amount of defocus into the amount of drive to be effected by the driving means, the conversion coefficients being intrinsic to the interchangeable lens and having values depending upon the discrete photographic distances of the optical system represented by the digital photographic distance signals, respectively. The digital photographic distance signals are applied to the circuit means as the predetermined input to cause the circuit means to output one of the conversion coefficients as the predetermined output, the value of which depends upon the photographic distance of the optical system represented by the one digital photographic distance signal being produced. The output conversion coefficient are transmitted to the camera body.