Timelapse, solved from any direction
You rarely know all three of interval, shoot time and final length. Fix the two you know and this works out the third — and tells you when the exposure will not fit inside the interval.
Timelapse planner
Interval starting points
Starting points, not rules. The right interval depends on how fast your subject actually moves, which varies more than any table admits.
Nothing leaves this device
The arithmetic
frames = final length × playback fps
shoot duration = frames × interval
final length = frames ÷ playback fps
The compression ratio — interval × fps — is how much faster than life the result plays. A 5-second interval at 30fps runs 150× actual speed: an hour becomes 24 seconds.
The mistake that ruins a shoot
Setting an exposure longer than the interval. The camera cannot start the next frame before finishing the last, so it silently drops frames and the result stutters. It is worse than it sounds because it usually happens partway through — as light falls at dusk, the exposure lengthens until it collides with the interval, and the smooth first half is followed by a juddering second half.
Leave real headroom. The camera also has to write the file, and a raw file to a slow card takes longer than you would think. If the exposure fills more than about 80% of the interval, this page warns you.
How long the clip needs to be
Shorter than instinct suggests. A single timelapse shot in a finished edit usually runs 4 to 10 seconds — long enough to read, short enough not to outstay its welcome. At 30fps that is 120 to 300 frames, which at a 5-second interval is 10 to 25 minutes of shooting. People routinely shoot for hours and produce 40 seconds nobody watches to the end.
Battery and card, not the camera
Past an hour or two, the limits stop being photographic. A mirrorless body with the screen live will not last a four-hour session on one battery; a DSLR with the mirror locked might. Cold cuts battery life sharply. And if you are shooting raw at short intervals, the card fills faster than you expect — the storage figure above is worth checking before you leave.
Related
Astro exposure planner for the night sky, and ND filters for daytime intervals that need motion blur in each frame.
Questions people actually ask
What interval should I use?
It depends entirely on how fast the subject moves, which is why the presets above are labelled as starting points. Roughly: one second for traffic and people, three for a sunset or moving cloud, ten for slow cloud, twenty-five for stars, minutes for plants and building sites. Shoot a short test and play it back before committing to hours.
How many frames do I need?
Multiply the clip length you want by the playback frame rate. Ten seconds at 30fps is 300 frames. Most finished timelapse shots run four to ten seconds, so 120 to 300 frames is the usual target — far fewer than people expect.
Why is my timelapse stuttering?
Most often the exposure grew longer than the interval partway through — typical at dusk, as the light falls and the camera compensates. The camera then drops frames it could not start in time. Leave headroom: if the exposure fills more than about 80% of the interval, you are at risk, and this page will say so.
Should I shoot raw or JPEG?
Raw if the light will change, because you will need the latitude to smooth the transition. JPEG if the light is constant and you want to shoot for hours without filling the card. A 300-frame sunset in raw is around 7 GB; the same in JPEG is under one.
What is the speed-up figure?
Interval times playback frame rate — how much faster than reality the result plays. A 5-second interval at 30fps is 150×, so an hour of real time becomes 24 seconds on screen.