Individual holes spaced at standard intervals (35mm typically 4 holes per frame) — ensure sync between camera and projector. Torn perforation = ruined take.
Perforations
The perforations are the mechanical backbone of classic film transport. The transport mechanism engages with the film strip—on 35mm standard, four perforations per frame—pulling the film synchronously through the camera and projector. Without these precise spacings, there is no continuous image, no projection. The perforations are a physical prerequisite for everything that follows.
On set, the importance of the perforations becomes immediately apparent when something goes wrong. A damaged perforation edge—torn, crushed, frayed—makes the entire film unplayable at that point. This is unlike digital formats, where individual faulty frames can be overwritten. Here, the information is literally embedded in the material. That's why we handle film rolls with respect: no sharp winding edges, careful when loading into the camera, straight to the darkroom after shooting. A tear in the perforation at the end of a long day's roll means material is lost because the projection mechanism can no longer engage it.
It becomes particularly critical during rewinding or film handling in the lab. Old prints that have been run multiple times often show signs of wear on the perforation edges—the holes become wider, frayed, and the mechanical transport sprockets lose their firm grip. This leads to image jitter or jumps during projection. Some lab technicians can still salvage damaged perforations with careful work, but it's craftsmanship at the limit. For valuable original negative rolls, only foam transport sprockets are used, which do not damage the perforations.
The tolerances are tight—the spacing between the holes can vary by only a few tenths of a millimeter, otherwise the film transport will not engage cleanly. That's why there are perforation standards (Academy, BH, Techniscope—depending on which image area is used) in film manufacturing. When editing and archiving, this must always be kept in mind: the perforation is not just a means of transport, but also defines where the actual image area lies. Cutting too close to the perforation edge can lead to damage and later playback problems.