The invention relates to a registration system (13) for registering an optical shape system to an imaging system with an imaging device (2) like a radiation C-arm device with a tracking device (4) like an optical shape sensing tracking device. One or more optical cameras (27) are used to detect position information of a tracked object to register the shape coordinate system with that of the imaging system. The optical cameras are pre-calibrated with the imaging system, so that the detected position information in the camera system can directly be translated to the imaging system.