The BBC bought the studios in 1955, though productions bearing the Ealing name continued to be made at the MGM British Studios at Borehamwood for two years. The BBC based its Film Department at the studios; and at its peak 56 film crews used the studios as a base for location filming of dramas, documentaries and other programmes; shot on 16 mm and occasionally 35 mm film. Led by a director, these crews usually consisted of a Lighting Cameraman, a camera assistant, a lighting technician (known as a 'spark'), and a sound recordist. Initially these crews were equipped with Arriflex ST cameras and EMI L2 quarter inch tape recorders that had to be tethered to one another with a physical sync cable to ensure the picture and sound ran in lock. In later years, Eclair NPR cameras replaced the Arriflex machines and Nagra tape recorders replaced the EMI units. The Nagras made use of 'crystal sync', a system that provided synchronisation between the camera and the tape recorder remotely, removing the need for a physical cable. There were also over 50 cutting rooms, equipped with Steenbeck editing tables, working on every genre except News and Current Affairs.