In the days before the Steadicam, gyro stabilizers and remote heads, cinematographers were often compelled to devise complicated ways to gracefully traverse uneven terrain.
Here, filming director William Friedkin's The Exorcist (1973), Owen Roizman, ASC takes a crack at operating a "Panavized" Arri IIC while doing a rehearsal for a complex stairwell tracking shot. He’s riding a "floating" platform built by key grip Eddie Quinn, who is maneuvering the rig with the help of dolly grip Jack Volpe. Camera operator Enrique Bravo observes from the railing. The seat was suspended from tracks mounted to the ceiling and smoothly raised through the stairwell by means of an electric hoist and pulley system, pacing the actors as they climbed upward.
Soft-lighting the scene from above allowed the camera to see for virtually 360 degrees and removed most shadows.
Roizman earned an Academy Award nomination for his expert camerawork.
A 1997 AC retrospective article on the making of The Exorcist is available here.