In a camera system according to the present invention, a lens controller obtains an exposure synchronizing signal that is generated by a camera controller from a camera body, causes a configuration formed of a first encoder, a second encoder and a counter to detect the position of a focus lens according to the obtained exposure synchronizing signal, and notifies the camera body of the detected position of the focus lens. The camera controller associates the position of the focus lens or the mechanism member obtained from the lens controller with an AF evaluation value based on the exposure synchronizing signal, and controls an autofocus operation of the camera system based on the position and AF evaluation value that are associated with each other. With this configuration, it is possible to improve the accuracy of an autofocus operation with a contrast system.