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Filmmaking Dictionary: Number 3 / 3-Perf 35mm
Definition
3-perf 35mm is a motion-picture format in which the camera advances 35mm film by three perforations for each frame. At the same frame rate, it uses 25% less film length than a four-perforation movement.
The format provides a useful compromise between film economy and image height. It can suit widescreen acquisition while retaining more vertical room than a two-perforation frame.
Running Time and Film Consumption
A 3-perf movement travels three-quarters of the distance of a 4-perf movement for each frame. The same roll therefore lasts one-third longer, not merely 25% longer. Those are two ways of describing the same change from different starting points.
At 24 fps, a nominal 400-foot roll provides roughly five minutes and fifty-five seconds in 3-perf, compared with roughly four minutes and twenty-five seconds in 4-perf. Treat those as planning figures before loading waste, tests and the production’s practical reserve.
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Framing Choices
The exposed gate and intended crop determine the final shape. A 3-perf camera can record material intended for different widescreen presentations, but the crew must use the correct frame lines. The perforation count alone is not a complete delivery specification.
For example, a production can protect a 16:9 composition while recording a gate area suitable for that workflow. If a wider scope version is also required, the director and cinematographer should decide how much image height can be lost and which version drives the composition.
Camera and Laboratory Requirements
- Confirm that the camera has the correct 3-perf movement and gate.
- Use a viewing screen or guides that match the intended image area.
- Identify the format clearly on camera reports and lab instructions.
- Arrange scanning and framing with post before the first exposed roll.
- Calculate stock needs using the selected frame rate and actual shooting plan.
Common Mistakes
A 3-perf negative cannot be treated as though its frames have standard 4-perf spacing. The scan or transfer must recognize the correct movement. Likewise, changing the intended ratio in an edit does not change how much film the camera consumed.
Budget savings should also be assessed across the whole workflow. Camera availability, testing, processing arrangements and finishing requirements remain part of the decision alongside the raw stock calculation.
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Frequently Asked Questions
Does 3-perf use a different film width?
No. It still uses 35mm stock; the frame advance changes.
Is 3-perf a frame rate?
No. Perforations per frame and frames per second are separate specifications.
Related Terms
Browse all terms starting with 3 or return to the filmmaking dictionary.