Focus puller
From Tardis Wiki, the free Doctor Who reference
A focus puller, sometimes known as a 1st assistant camera on other programs, is a member of the production team whose primary responsibility is to maintain focus. The action of "pulling focus" refers to the changing of the focus either as a subject moves in relation to the camera, or as the focus shifts from one subject to another.
They are also the most senior camera assistant on a program, and are often responsible for running the camera department in the absence of a camera operator (i.e. when the director of photography is operating).
