Recording at 240 frames per second and playing back at 30 makes motion 8 times slower, slow enough to see a wrist snap or a foot plant clearly. The catch with the built-in Slo-mo mode is that someone has to press record before every rep. A buffered slow-motion camera removes that job: it holds the last seconds at 240 fps in memory, so the swing that just happened is always capturable with one tap after the fact.
What fps means for slow motion, in one paragraph
A normal video shows 30 pictures per second. A slow-motion camera captures many more, then plays them back at the normal rate. Capture 240 pictures in one second and play them at 30 per second, and that one second takes 8 seconds on screen. Everything in it, the hip turn, the release point, the moment of contact, spreads out so the eye can actually follow it. At 120 fps you get 4x slower, which is often enough for running form; at 240 fps you can study a golf club through impact.
Why a buffer beats the built-in Slo-mo mode for technique
The iPhone Slo-mo mode records forward from the moment you press the button. That works for one planned shot. It falls apart during a practice session, because a coach watching reps does not want to be a camera operator. Starting and stopping for every swing means eyes on the phone instead of the athlete, a pile of files to sort, and inevitably a missed press on the one rep worth keeping.
A rolling buffer flips it. The camera continuously holds the most recent seconds at 240 fps in memory, saving nothing. The coach watches the athlete, not the screen. When a rep is worth keeping, one tap saves the seconds that already happened. The rep you just saw with your own eyes is the rep you get in slow motion, every time, with zero anticipation required.
The honest resolution tradeoff
Higher frame rates mean the sensor has less time per frame, so resolution drops. No phone shoots 4K at 240 fps. The real options look like this:
| Resolution | Maximum frame rate | Good for |
|---|---|---|
| 4K | up to 60 fps | Sharp full-speed footage, light slow motion |
| 1080p Full HD | up to 120 fps | 4x slow motion with plenty of detail |
| Up to 720p | 240 fps | 8x slow motion for technique analysis |
720p sounds modest, but for technique work it is the right trade: you are studying body positions, not printing posters. Note that 240 fps is available with some back cameras only, so which formats you see depends on your device.
The other end of the table matters just as much: the buffer itself costs no quality. The app pre-records in the same full 4K the normal camera app shoots, so "recording the past" does not mean a downgraded picture. Most buffer and pre-record tools give you nothing close to that; if the moment might end up on a big screen, buffer in 4K and slow it down later.
How to set the frame rate
- Open Settings in the app and tap the camera format cell, the one showing the current format as "width x height @ fps", for example 1920x1080 @ 30.
- Pick the resolution and frame rate combination you want, for example a 720p format at 240 fps for maximum slow motion.
- Back on the main screen, set your Buffer duration. A golf swing fits in 5 to 10 seconds; a gymnastics pass may want 20.
All camera formats and frame rates are part of the premium subscription, described here qualitatively because the exact tiers can change.
Gym lighting: stabilization and ISO
Indoor sports are hard on cameras. At 240 fps each frame gets very little light, so gym footage can come out dark. The app exposes a Camera ISO control: slide it higher for indoor courts and the image brightens, at the cost of some grain. If you are filming handheld rather than from a tripod, Video stabilization offers several modes from Standard to Cinematic to smooth out your grip.
What to point it at
Buffered 240 fps earns its keep anywhere a fast movement repeats: a golf swing on the range, a baseball pitch in the bullpen, a tennis serve, a gymnastics rep, a sprinter's block start. Film the session, tap after the good ones, and walk away with a short list of slow-motion clips instead of an hour of tape. When you want frame-by-frame stepping or a side-by-side of two swings, that review happens in the companion app, Coach Video Analysis.
Do this in Video Buffer Action Camera
Everything above is built in: a rolling buffer of 2 to 100 seconds, 240 fps slow motion at up to 720p, 4K at up to 60 fps, the camera format picker in Settings, Camera ISO and Video stabilization for gym conditions, and Save Buffer Only so one tap saves one finished rep. Longer buffers and all camera formats are part of the premium subscription.
