number of perforations long and which moves the film with sprockets inside the magazine. Some more recent 35 mm cameras from Arri and all Moviecam and Panavision cameras, however, do not have any required loop size, and the film is not controlled with any sprockets in the magazine at all. Instead, the film is pulled through the camera solely through the power of camera sprockets until the end, at which point springs or belts in the camera magazine pull the film back to the take-up side. Design Another major categorization is the type of design: is the magazine one chamber or two chambers? If the latter, are the two horizontal or axial to each other? Most 35 mm camera magazines are one large chamber containing both spindles - usually the spindles are close enough together so that the feed and take-up rolls will just miss touching each other when the maximum length of film for that magazine is at its halfway point. Cameras with the single chamber magazine design include all Panavision and Moviecam cameras, most 35 mm Arri cameras, and all older 16 mm Arri cameras. Some old cameras, such as the Mitchell, have two separate chambers horizontal to each other, which looks very similar to a one chamber design. More popular today in two chamber design, however, are two chamber axial magazines, where the feed and take-up rolls (and thus chambers) are "stacked" one atop the other. Cameras with this magazine design in 16 mm include the Aaton and Arri SR models, and in 35 mm include the Arri BL and 535 models. Responsibility The camera magazine tends to be held mostly in the charge of the clapper loader on set, who is in charge of loading and unloading the magazine, labelling it properly, securing it as light-tight, and delivering and receiving magazines from the focus puller, who attaches and detaches them from the camera and handles the threading of the film in the camera (certain magazines require no camera threading). Loading Because of the length of motion picture film, the film usually is wound around a core, with no other exposure protection aside from its packaging or the magazine itself when loaded. Therefore, the loading of motion picture film must be done in a dark room or light-tight changing bag by the clapper loader. As the loader cannot see what (s)he is doing, the loader must already