Focus puller

British cinematographer Oliver Stapleton has written: The 1st AC (or Focus Puller) has one of the hardest jobs on the set.

A high-definition monitor can be particularly useful when a fast-paced production simply does not allow time for the focus puller to set and check all marks that may be needed, or if no rehearsal will be provided.

In most modern use cases, wireless video sender technology is employed to send a high definition or 4K signal directly to the focus puller.

[3] The 1st AC may take surveying measurements of the general environment in order to have a good idea of the distances between reference points, such as patterns on the floor or walls, furniture, and whatever else might be around.

These reference measurements can be used to quickly establish rough distances between the camera and the subject in chaotic shooting circumstances.