Frame rate — defines motion smoothness and slow-motion ratio. 24p cinema, 25p PAL, 30p NTSC, 60p minimum for slow-mo. Project frame rate changes require recalculation.
The frame rate determines how fluid or staccato motion appears on screen — and this isn't an aesthetic gimmick, but a technical necessity. You set your camera to a specific frequency, and this rhythm permeates the entire production process. 24 frames per second was long the standard for cinema because at this rate, the eye perceives motion as continuous while also saving film stock. 25p is for PAL countries (Europe, Australia), 30p for NTSC regions (USA, Japan) — historically determined, but still relevant if you're producing for television or regional broadcasts.
On set, you notice the difference immediately: at 24p, everything looks more cinematic, slightly dreamlike — which is why many cinematographers stick with it, even if the rest of the world has long moved to other standards. 25p and 30p appear crisper, closer to documentary real-time. However, once you enter the high-frequency zone — 50p, 60p, or even higher — slow motion becomes accessible. Shoot your camera at 60p and play back the material in 24p sequences: you get a 2.5x slow motion without loss of quality. 120p allows for a 5x slowdown. This sounds simple, but it's a pitfall in editing — if you accidentally import 60p material into a 24p project, it will appear unnaturally fast and jerky.
Practical Pitfalls
Most beginners underestimate how profound this decision is. You commit to a frequency on the shooting day — changing it later costs time and quality. High-speed cameras (100p+) require more light and faster shutter speeds because each individual frame has less time to be exposed. So, if you're planning for slow motion, you need to bring HMIs on set, not discover in the editing room that the footage is underexposed.
Another point: if you mix footage of different frame rates — for example, a 24p interview with 60p detail shots — you need to work consciously in the edit. Conversions using software interpolation (Timewarp, Twixtor) create artifacts. The clean solution is to reshoot or accept that the detail shot must run at full speed. Some productions therefore work entirely on a 50p or 60p basis and convert down later — this gives you maximum flexibility in post-production.