Follow focus controller circuit, follow focus controller and photographic system

A follow focus controller circuit, comprising a main circuit and at least one expansion circuit;

• wherein the main circuit includes a main control unit, a first detection unit, a transmission unit and at least one first connector, the main control unit being electrically connected to the first detection unit, the transmission unit and the first connector;
• wherein the expansion circuit includes a second detection unit and a second connector adapted for connection with the first connector, the second detection unit is electrically connected to the second connector, and the second connector is configured to be electrically connected to the first connector;
• wherein the first detection unit and each second detection unit are respectively configured to detect angular positions of their corresponding rotary adjustment members and transmit detecting signals to the main control unit;
• the main control unit is configured to process each of the received detecting signals individually and output the processed detecting signals via the transmission unit.