Once a camera position or overall "shot" is established by the director of photography and camera operator, the 1st AC begins to measure the various distances between the actors' marks and the focal plane of the camera. These distances are recorded in a series of grease pencil or pen marks on the focus barrel of the lens; similar marks may be placed on the marking disc or ring of any follow focus device being used. Traditionally, the focus puller used only their marks and their own well-developed sense of distance estimation to achieve good results. Over the last decade, the increased use of digital cameras, higher-resolution
video taps, and on-camera monitors has provided focus pullers with additional tools to help maintain proper focus. 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. 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. The 1st AC reports to the
director of photography, works alongside the
camera operator, and oversees the
2nd assistant camera (also known as the "clapper loader") and any other members of the camera department. ==References==