Apple Cinema Tools 4 - Manual (Page 230)

Because of its lower costs, 16mm film is typically used for productions with smaller
budgets. If you intend to shoot 16mm but release your project as 4-perf 35mm, you
should use Super 16mm film. It has perforations along only one edge and a larger frame
that more closely matches the 4-perf 35mm aspect ratio.
16mm format Super 16mm
35mm film is most commonly used for theatrical releases, with 4 perforations per frame
(4-perf ) being the most prevalent version. Another common version uses 3 perforations
per frame (3-perf ). There are other versions of 35mm, such as 8-perf, but they are not
currently supported by Cinema Tools.
35mm format 35mm format
4-perf 3-perf
Perforations
Camera and projection equipment uses the perforations, also known as sprocket holes,
along one or both edges of film to pull it past the shutter.
16mm Film
16mm film has a single perforation for each frame, which comes out to 40 perforations
per foot. 16mm is available as single perforated (perforations along one edge only, allowing
space for an optical track, or in the case of Super 16mm film, for a larger frame) and
double perforated (perforations along both edges). Cinema Tools supports single and
double perforated 16mm film as long as it has a key number every 20 frames. See
Key
Numbers for more information.
230 Appendix A Film Background Basics