Follow Focus Units: The What and Why

Kinor 35H with Follow Focus Unit
Kinor 35H with Follow Focus Unit
Follow Focus Unit - the What:

A Follow Focus Unit attaches to the focus ring of a manual lens to aid in adjustment of the focus to a given focal point which may or may not be the subject directly in the center of the lens.

Usually, a Follow Focus Unit is attached to and supported by a set of rails, that, in turn, are attached to the camera. The Follow Focus Unit works the focus of the lens through a set of gears wrapped around the lens' focus ring.

Follow Focus Unit - the Why:

It is often much easier to pull focus (or follow the focus) with a Follow Focus Unit rather than manipulating the focus ring by hand, as going it by hand could possibly affect the rigidity of the shot. Focus pulling by hand may also lend to pushing or pulling the camera in a given direction while the camera is handheld or while panning or tilting (or other camera movements). Because of the the gearing system, a Follow Focus Unit can also allow a focus puller to adjust the focus by minute increments much easier than pulling focus by hand.

With the proper attachments (in this case, a whip, which is a cable with a rotating knob at the end that plugs into the rotating wheel of the Follow Focus Unit), a Follow Focus Unit can even allow a focus puller to stand away from the camera, so as not to affect the shot in any way, other than his/her duty of pulling focus.