Many people automatically assume that in video and film production, as in some professional positions, assistant positions are simply subservient to a more proficient level of the same craft. Without understanding that an Assistant Director is an indispensable part of film production with a whole series of specific and advanced tasks it would be hard to see them as anything but the assistant to the Director. The Assistant Camera position can be seen in this way too, yet this position may be one of the most difficult and technically minded ones in any film production.
The first Assistant Camera role, assuming that there are more than one Assistant Camera positions as there are on larger productions, is usually considered the "head" of the camera department. This makes the Assistant Camera position more technical than that of the Camera Operator or the Director of Photography.
If any type of general repair is going to occur on a production’s camera equipment it will have to be initiated by the Assistant Camera person. This leads into the preparation of all equipment for the said production, including renting or checking out the equipment, making sure that it is ready for production, and getting it up to par for any situation that it is going to have to undergo. The AC will then have to go through and complete camera equipment tests to make sure that the lenses are working appropriately, to see how the camera runs in an environment, and to test out different tapes or stocks.
One of the most important features that an Assistant Camera person is going to have to deal with is the focus of the camera in general. Part of this is going to rechecking the specific calibrations that will be on the focus ring of any different lens that you plan on using. To do this they will use different spatial distances and make sure that the lens they are using is in focus at that distance according to their listed settings.
When production is actually taking place the Assistant Camera will "pull focus." Pulling focus means that they will measure the accurate distance between the focus plane and the subject of the frame. The AC will then create detailed written notes for different positions, both of the actor’s movement and of the movement of objects in the scene. The best way for the AC to do this is to generally create marks on the camera tape that they place on the focus ring. This will allow for quick references back to the settings known for correct distances.
The best Assistant Camera people have the ability to check distances without much official measuring, though it is usually true that they will be running around at different areas measuring distances and making marks. When the Camera Operator is actually filming the Assistant Camera person may be on the machine as well adjusting focus and zoom.
The Assistant Camera person will also be in charge of preparing film stock and loading the camera. The actual weight of this job depends on the type of equipment you are using, as HDV is not going to be nearly as complicated as 16mm. This role continues the fact that an AC often gets little credit, yet can be directly responsible for the success of a given production.