Open just about any textbook on film-making, turn to the chapter on cinematography, thumb over to the section on camera movement and you will learn that there are two functions of camera movements: motivated and unmotivated. Motivated camera movements are easy to spot. A character walks across a road, and the camera follows them. The camera simply tracks the action across the screen by means of dollies, various hand-held techniques, or pans. Unmotivated shots are a bit more difficult to discern, because they occur when the camera chases the action more intimately. The character reaches the other side of the road and suddenly stops to look at her watch. The camera rushes in to a close-up of the watch face. Sometimes the camera will move unmotivated in such a way that it imposes upon the story itself. Tracking back from the watch to a long shot, the camera trails the character as they resume walking. They turn left and walk out of frame as the camera loses them and tilts up to the sky to reveal a jet contrail. This then amounts to two different points of view from the moving camera's perspective: observer and participant.

In the preceding chapters we explored the most basic form of movement in film – subject and object movements in front of the camera and within the projected image. That is, mobility within the frame. The aim of this chapter is to foreground the mobility of the frame itself, how a camera, itself in motion, captures the motion of subjects and objects it films. I will follow David Bordwell and Kristin Thompson's suggestion in Film Art: An Introduction that we define mobile framing to mean ‘that, within the image, the framing of the object changes. The mobile frame thus produces changes of camera angle, level, height, or distance during the shot’ (Bordwell and Thompson 2004: 266).