Time-Lapse Calculator

In short A time-lapse is three numbers tied together: the interval between shots, how long the event lasts, and the frame rate you play it back at. Frames equals shooting time divided by interval; clip length equals frames divided by frame rate. Shooting for an hour at one frame every five seconds gives 720 frames, which at 24 fps is exactly 30 seconds of finished clip and a 120 times speed-up. Give any two and the third follows, which is what this tool does in all three directions. Choosing the interval is the part that takes judgement, and the principle is that nothing should move more than a small fraction of the frame between consecutive shots. Clouds usually want 2 to 5 seconds, a sunset 5 to 15, stars 20 to 30, and construction or plant growth minutes or hours. Too long an interval gives a jerky result that no amount of processing will smooth; too short wastes shutter actuations and card space. Two practical constraints bite harder than people expect. The frame count is also a shutter count — 720 actuations is a real fraction of a mechanical shutter's rated life, and a long lapse spends them quickly, so use the electronic shutter if the body has one. And storage adds up fast: 720 raw files at 25 MB is about 17 GB. Finally, shoot in manual. Any automatic exposure will hunt between frames and produce flicker, which is the single hardest thing to remove afterwards.