How to film a presentation practice video with both iPhone cameras
Rehearsing a talk normally means picking one of two incomplete views. Prop the phone to record your own delivery and you can check eye contact and pacing, but you have no record of whether you actually paused too long on a slide. Screen-record the slides instead and you get the content timing, but nothing about how you looked or sounded saying it. Comparing the two afterwards means two separate files on two separate timelines, guessing at which moment in one lines up with which moment in the other.
Recording the front and back cameras at once removes the guessing, because there is only one timeline to begin with. Your delivery and whatever the back camera is pointed at — slides, notes, a whiteboard — land in the same frame at the same instant, from the moment you start talking. Play it back once and both halves are already lined up.
Decide what leads: your delivery or your slides
Picture-in-picture with the back camera filling the frame is the right default when you are mainly checking pacing against content — whether you moved to the next slide at the right beat, whether you looked up before or after a transition instead of during it. The slides fill the recording and your face rides in a small window, present enough to read your expression without taking space away from what you are actually pacing yourself against.
When you are rehearsing physical delivery instead — eye contact, gestures, posture, whether you are talking to the audience or reading off the slide — a split gives your face the same amount of frame as your slides rather than shrinking it into a corner. Neither choice is fixed once you start recording: which camera fills the frame, and whether it is picture-in-picture or split at all, can both change while DualCam is rolling, so a run-through can start in whichever mode matches what you are checking that pass.
Framing slides so a split does not crop the text off
A left-and-right split crops roughly a quarter off each side of both source frames to fit a vertical canvas. A face tends to survive that fine, because a face is usually centred in its own frame to begin with. A slide is a different shape of problem: title text, a chart axis, a logo in the corner — the parts of a slide that carry information are routinely near its edges, which is exactly what a left-right split throws away on both sides, not just crops around.
Top-and-bottom keeps the full width of both source frames, which is why it is the safer split for slide content, and picture-in-picture with the slide camera filling the frame avoids the crop altogether. Save left-right for the run-throughs where the back camera is on something centred and static, like a whiteboard drawing you are standing next to rather than text that runs edge to edge.
Pointing the back camera at what you are rehearsing against
A laptop or monitor showing your slides
Level the phone with the screen and keep the lens roughly perpendicular to it. Shoot a rectangle from an angle and the sides converge instead of staying parallel, which reads as an obviously crooked slide even when the text itself is perfectly legible. If the room does not give you enough distance to fit the whole screen at a normal angle, the ultra wide lens (where your iPhone has one) buys back some of that distance without you having to back further away — but which lens is active is one of the settings that has to be chosen before you press record, not switched mid-rehearsal.
Printed notes, cue cards or a whiteboard
There is no backlight to fight here, but there is nothing correcting for a bad angle either. A whiteboard shot from the side turns straight lines into a wedge the same way an angled monitor does, and overhead light on paper or a glossy board can throw a hard glare exactly where you need to read something. Straight-on, with the light source in front of the board rather than behind you and reflecting off it, is worth the extra few seconds it takes to set up.
A bright screen and a dim room are two separate exposure problems
The front and back cameras set exposure independently, each one reading only the frame it sees, with nothing coordinating the two decisions. A laptop or monitor is one of the brighter things in most rooms, so it is common for the back camera to expose correctly for the screen while the front camera, under whatever ordinary room light you are standing in, reads your face as noticeably dim by comparison.
Tap the frame that needs help rather than trying to fix both at once — DualCam ties exposure to tap-to-focus, and each frame corrects independently, so tapping your own face pulls exposure toward you without touching how the slide looks. Turning down the screen brightness a notch, or moving so a bright window is not directly behind the laptop, closes the gap before you even need to tap anything.
Lock in resolution, mute and the countdown before you start talking
Resolution, the mute switch and the countdown timer all fix themselves the instant recording starts, because each one changes how the file itself gets built rather than how it looks. For a rehearsal, leaving mute off is close to a given — your voice is most of what there is to review — and a 5 or 10 second countdown is worth using so you are already standing at your mark and starting to talk when the take begins, instead of still walking back from the phone.
Layout, the picture-in-picture corner, its size and shape, and the colour filter stay open the entire time, so none of that needs deciding in advance. Get the four settings that lock right once, and everything else is free to change between run-throughs or even mid-sentence if a slide calls for it.
Treat every run-through as its own take
A dual-camera recording runs straight through from record to stop with no way to pause it mid-file and pick up again later in the same recording. For a rehearsal that is not a limitation worth fighting — it is closer to the right shape already. Run the talk start to finish, press stop, and start fresh for the next attempt, rather than trying to freeze mid-sentence and resume where you left off.
Every take gets kept in DualCam’s built-in library with a thumbnail, so five run-throughs across an evening sit next to each other ready to compare, instead of one long recording you have to scrub through to work out where one attempt ends and the next begins. Save or delete each one once you know whether it earned a place in the pile you keep watching back.
Common follow-up questions
Should I use picture-in-picture or split screen to practice a presentation?
It depends what you are checking. Picture-in-picture with your slides filling the frame suits checking pacing — whether your delivery matches the slide timing. A split gives your face equal weight instead of shrinking it into a corner, which suits rehearsing delivery itself: eye contact, gestures, posture.
Why does a left-right split cut off part of my slide?
To fit a vertical canvas, a left-right split crops roughly a quarter off each side of both source frames. Slide content like titles, chart axes and corner logos is often near those edges, so it is exactly what gets cropped. Use top-and-bottom, which keeps the full width, or picture-in-picture with the slide camera filling the frame.
Can I pause a run-through and keep recording into the same file?
No — a dual-camera recording has no mid-file pause. Stop and start a new take instead, which fits rehearsal naturally: each run-through becomes its own file, saved with a thumbnail in DualCam’s library so you can compare attempts side by side rather than scrubbing through one long recording.
Want to just do this?
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