A camera system includes a camera body and a photographing lens which is detachably attached to the camera body. The photographing lens has an input and output device which inputs and outputs data to and from the camera body, a timing controller which outputs clock pulses for driving the input and output device, and a loading device which loads specific initial value lens data in the input and output device in accordance with the clock pulses. The camera body includes an information processing device which receives the specific initial value lens data loaded in the input and output device.