Camera assistant

A focus puller, or 1st assistant camera, is a member of a film crew’s camera department whose primary responsibility is to maintain image sharpness on whatever subject or action is being filmed.

"Pulling focus" or "rack focusing" refers to the act of changing the lens’s focus distance setting in correspondence to a moving subject’s physical distance from the focal plane. For example, if an actor moves from 8 m away from the focal plane to 3 m away from the focal plane within a shot, the focus puller will change the distance setting on the lens during the take in precise correspondence to the changing position of the actor. Additionally, the focus puller may shift focus from one subject to another within the frame, as dictated by the specific requirements of the shot (cinematic techniques).

A good focus puller will have an intimate knowledge of cinematographic and optical theory. Depending on the parameters of a given shot, there is often very little room for error. As such, the role of a focus puller is extremely important within the realm of a film production; a "soft" image will, in most circumstances, be considered unusable, since there is no way to fix such an error in post-production. One must also consider that an actor may not be able to duplicate his or her best performance in a subsequent take, so the focus puller is expected to perform flawlessly on every take. Because of these factors, some production personnel consider the focus puller to have the most difficult job on set. For example, British cinematographer Oliver Stapleton has written:

During production, 1st ACs are also responsible for the maintenance and upkeep of all camera equipment and accessories, such as lenses, filters, batteries, film magazines/recording media, matte boxes, etc., and for configuring the camera and its accessories in multiple ways for different setups. 1st ACs arrive on set or in the studio before the director, director of photography (DoP) and camera operator, and ensure that the camera and all required lenses are prepared for the day's shoot. During shooting, the 1st AC is also responsible for moving the camera to each setup as directed by the Director of Photography. On larger budget productions, the camera is usually mounted on a dolly for most of the day, which is operated by the Dolly Grip. At the end of each shooting day, 1st ACs clean the equipment and pack it up in preparation for the next day. If there is a problem with the rushes (such as a scratch on the film), the focus puller communicates with the film lab to fix any faults with the camera or film stock.

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