This invention relates to an improvement in an interchangeable lens having electrical contacts through which information is transmitted to the camera body.
In general, in order to perform automatic exposure control, and to indicate the shutter speed and the aperture value according to the automatic exposure control, information or data on the lens such as the full-aperture value or minimum aperture value of an interchangeable lens must be transmitted to the camera body when the interchangeable lens is mounted on the camera body.
For this purpose, i.e., in order to transmit lens data as electrical signals to the camera body, a method has been proposed in the art in which electrical contacts are provided on the mounts of the camera body and the photographing lens in a manner such that the electrical contacts protrude somewhat from the srufaces of the mounts. When the interchangeable lens is mounted, the circuits are completed, whereby the inherent aperture data or the like of the interchangeable lens are transmitted to a control circuit or the like on the camera body side.
However, this method is disadvantageous in the following point: As the electrical contacts protrude, in mounting the interchangeable lens, the electrical contacts on the camera side and the electrical contacts on the lens side may rub against one another, as a result of which electric power is uneconomically consumed, the control indication and calculation may include errors, and the lens cannot be mounted smoothly.