A camera system with an auto-focusing system includes a camera body and an interchangeable zoom lens. The interchangeable objective lens stores various data to be sent to the camera body for improving automatic focus adjustment, such as an information necessary to convert the detected defocus information into a movement of the driving power source to carry out the automatic focus adjustment. The driving power source in the camera body is controlled in response to the data from the interchangeable objective lens and the detected focus information, the driving power being transmitted to the interchangeable objective lens. The camera body is further capable of inhibiting the focus adjustment or focus indication in response to a data from the interchangeable objective lens under an unfavorable condition.