Time Lapse Interval Calculator

A time lapse compresses real time by a fixed factor. If frames are captured every I seconds and played back at F frames per second, the apparent speed-up is simply I multiplied by F: a 5-second interval played at 24 fps runs 120 times faster than reality. Working backwards, the frame count needed for a clip of length C seconds is C multiplied by F, and the interval is the event duration in seconds divided by that frame count. A 2-hour event rendered as a 30-second clip at 24 fps needs 720 frames and therefore a 10-second interval. The same arithmetic drives the secondary outputs here: total frames multiplied by the per-file size gives card space, and shutter actuations divided by roughly 700 to 900 frames per battery gives a rough power budget for unattended shoots. Interval choice is dictated by how fast the subject moves across the frame, not by taste. Common working figures are 1 to 3 seconds for traffic and pedestrians, 2 to 5 seconds for sunsets and fast clouds, 10 to 30 seconds for melting or tidal change, 20 to 30 seconds for star fields, 1 to 5 minutes for plant growth, and 5 to 30 minutes for construction. Two hard constraints apply: the interval must exceed the exposure time plus buffer write time or the camera will skip frames, and interval alone cannot fix flicker. Frame-to-frame exposure variation of even a tenth of a stop pulses visibly, which is why manual exposure, manual white balance and apertures wider than about f/8 are standard practice.

Interval photography began as a scientific instrument rather than a cinematic effect. The German plant physiologist Wilhelm Pfeffer photographed germinating seedlings at fixed intervals in the 1890s to make growth movements visible, and the technique spread quickly through botany and microscopy. British naturalist filmmaker F. Percy Smith produced widely seen time-lapse films of growing and opening plants for Charles Urban in the early 1900s, and in the mid-twentieth century the American photographer John Ott built elaborate motorised time-lapse rigs for plant studies whose footage was used in Disney nature films. Because early cameras had no timing electronics, the interval was enforced by clockwork intervalometers driving the shutter and film advance. Playback rates were fixed by cinema convention: 24 frames per second became the standard when synchronised sound arrived at the end of the 1920s, with 25 fps for PAL television areas and 30 fps for NTSC. Time lapse moved from laboratory tool to expressive form with films such as Godfrey Reggios Koyaanisqatsi in 1982, which built much of its imagery from compressed urban and landscape motion. The shift to digital SLRs in the 2000s replaced film cost with card space and shutter life as the limiting factors, made per-frame RAW capture practical, and produced a generation of dedicated intervalometers, in-camera interval timers and deflickering software aimed specifically at holy grail day-to-night sequences.