01The number that catches everybody out
A ten-second clip at 25 frames per second needs 250 photographs. At a four-second interval that is nearly seventeen minutes standing next to a tripod. Push it to a satisfying thirty-second sequence and you are there for fifty minutes, and a two-minute finished piece is most of a day. Time-lapse is the most patience-intensive thing you can do with a camera, and the finished clips are so short that people consistently underestimate it by a factor of five.
Plan around this before you drive somewhere. Bring something to sit on, more battery than you think, and accept that you will get two or three usable sequences in a session rather than ten.
02Choosing an interval
The rule is simple: the interval has to be short enough that nothing important moves more than a small fraction of the frame between frames. If a cloud crosses your whole composition in two minutes of real time and you shoot every eight seconds, that cloud jumps in visible steps and the clip strobes. Halve the interval and it flows.
What matters is not the subject's actual speed but its apparent speed in your frame, so focal length changes the answer. The same cloud shot at 200mm needs a much shorter interval than at 16mm, because it crosses the frame far faster. When you are unsure, shoot shorter than you think: you can always drop every second frame in the edit, and you can never invent one that was not taken.
03Shutter speed: the difference between flowing and strobing
Set the shutter to about half the interval. This is the time-lapse version of the 180-degree rule in video, and it is the single biggest quality difference between amateur and professional time-lapse. Each frame carries enough motion blur to overlap with the next, so movement reads as continuous rather than as a series of frozen instants.
In daylight this means a two-second exposure at a four-second interval, which is impossible without a strong neutral density filter. A 6 or 10-stop ND is standard time-lapse equipment for exactly this reason. If you cannot get there, a shorter shutter still works, it just looks noticeably more staccato, and the effect gets worse the faster the subject moves.
04Two things to switch off before you start
Autofocus and image stabilisation. Autofocus will hunt slightly between frames and the tiny differences show up as a pulsing softness. Stabilisation on a tripod tries to correct movement that is not there and can drift the frame over hundreds of exposures. Lock focus manually, turn stabilisation off, and use manual exposure so the camera does not re-meter and flicker.
Auto white balance. Same reasoning. Left on auto, it will shift by small amounts between frames and produce a colour flicker that is tedious to remove afterwards. Set it once, on Kelvin, and leave it. If you shoot RAW you can change it later for every frame at once, which is the other reason to shoot RAW for anything where the light changes.
05Frequently asked questions
Two to five seconds for normal cloud, one to two for fast storm cloud, up to eight for high thin cirrus. If the cloud crosses your frame in under two minutes of real time, go shorter.
About half the interval, the time-lapse form of the 180-degree rule. It gives each frame enough motion blur to blend into the next. In daylight that needs a strong ND filter.
RAW whenever the light changes during the sequence, which is every sunrise, sunset and day-to-night shot. JPEG is defensible for long sequences in constant light. Remember a 3,000-frame sequence is 3,000 mechanical shutter actuations.
Almost always auto exposure, auto white balance or an aperture that is being re-set between frames. Lock exposure and white balance manually. On some lenses, using the aperture wide open avoids the tiny diaphragm inconsistencies that cause the rest of it.