Controlling lens focus so that an image maintains sharpness and clarity despite camera and/or subject movement.

a circular knob which the focus puller uses to adjust the focus onto different subjects as well as change, or (follow) focus during movement of the camera onto the required subject, hence the term

Shot in which the camera focus is changed to compensate for the movement of the action or the camera itself.

To change the focus setting of a lens as a scene is being photographed to keep a moving subject in sharp focus.

Controlling lens focus to maintain sharpness and clarity despite camcorder or subject movement.

A follow focus is a piece of equipment that attaches to the focus ring of a manual lens via a set of rods on the body of a film or video camera. It is ergonomic rather than strictly necessary; in other words it does not contribute to the basic functionality of a camera but instead allows the operator to be more efficient and precise. It is usually operated by a focus puller (often called the 1st assistant camera, or 1AC) but some camera operators prefer to pull their own focus (the act of changing focus is called "pulling" or "racking" focus).