How to make a clean timelapse with an iPhone
To make a timelapse you need three numbers and one lock. Here is how to work out the interval, avoid flicker, and not waste an hour-long session.
A failed timelapse is never visible during capture. You set the tripod down, walk away for an hour, and come back to find the sequence blinking, or stopped at photo three hundred and twelve. There is no second chance: the light has gone.
So everything is decided before you press the button. Here are the four decisions, in order.
1. Working out the interval
A timelapse is an equation with three unknowns:
- the real duration of the scene,
- the length of video you want,
- the interval between frames.
Fix two and the third follows. The formula is simple:
interval = real duration ÷ (video length × frames per second)
An example. You shoot a sunset for 30 minutes, which is 1,800 seconds, and you want 20 seconds of video at 30 frames per second, which is 600 photos. The interval is therefore 1,800 ÷ 600 = 3 seconds.
Here are the orders of magnitude that work, for a video of around twenty seconds:
| Subject | Interval |
|---|---|
| Fast clouds, crowds | 1 to 2 s |
| Sunset | 3 to 5 s |
| Shadows across a day | 15 to 30 s |
| Building site, growing plant | 5 to 30 min |
2. Locking, which fixes the flicker
This is what separates a clean timelapse from an amateur one, and it has nothing to do with your gear.
Between two frames, a camera in automatic readjusts exposure and white balance by a few per cent. On a single image that is invisible. Assembled at twenty-four per second, those micro-corrections become a constant blink, known as flicker.
The fix is to lock before you start: ISO, shutter speed, white balance and focus. Once frozen, every frame shares exactly the same rendering.
The special case is a sunset, where the light really does fall by several stops during the session. Two options: accept that the end will be dark, or go semi-automatic by locking only the white balance and the focus. Either way, the colour flicker disappears.
3. To make a timelapse over an hour without wasting it
Three causes, always the same ones.
The battery. An iPhone capturing continuously for two hours with the screen on will not make it. Plug it in, and turn the brightness right down.
Disk space. A full-quality photo weighs between 2 and 4 MB. Nine hundred photos is therefore between 2 and 4 GB. Do that arithmetic before, not during.
Movement. A tripod, always. Not a phone propped against a bottle. Over an hour, the slightest slip shows on screen as a jump.
And check the horizon level before starting. Two degrees of tilt cannot be recovered in the edit without cropping the whole sequence.
4. Hyperlapse, which is a different craft
A hyperlapse is a timelapse in which you move between each frame. The result is spectacular and the difficulty is real: you have to keep the same subject in the same place in the frame across hundreds of steps.
Three things genuinely help:
- Pick a reference point in the frame, and keep it in exactly the same place.
- Take regular steps, short and of constant length. One step per photo is a good rhythm.
- Line up on the previous frame, if your app overlays the last photo in transparency on the viewfinder.
The rest is corrected at assembly, by stabilisation, but no stabilisation rescues framing that wanders everywhere.
The tool I use
The iPhone’s native app allows none of these settings: it has one button, picks the interval on its own, and leaves exposure automatic. That is why I wrote Interval Pro, which locks all four settings, computes the interval in either direction, and states the photo count, the disk space and the battery before starting. It also refuses to begin a session it knows it cannot finish.
The summary
Work out the interval before you leave. Lock the exposure. Plug the phone in. And set down a tripod, not a bottle.