Time Lapse Calculator

Time lapse arithmetic rests on three linked quantities. The frame count equals the shooting duration in seconds divided by the interval between exposures, the clip length equals that frame count divided by the playback frame rate, and the compression of time, usually called the speed-up factor, equals the interval multiplied by the frame rate. A 5 second interval played back at 24 frames per second therefore compresses events by 120 times regardless of how long the session runs, and one hour of shooting yields 720 frames or 30 seconds of footage. The consequence practitioners plan around is that footage accumulates slowly: producing a single minute of 24 fps time lapse at a 5 second interval requires two hours in the field and 1,440 exposures. Interval choice is governed by how much the scene changes between frames. Fast cumulus typically calls for 1 to 3 seconds, general cityscapes and pedestrian traffic 2 to 5 seconds, sunsets and sunrises 5 to 10 seconds, night sky sequences 20 to 30 seconds constrained by star trailing, and construction or plant growth minutes to hours. A common exposure convention borrowed from cinema sets the shutter near half the interval so consecutive frames carry overlapping motion blur and the result reads as continuous rather than strobed. The dominant practical problem is flicker, caused by small frame-to-frame variations in mechanical aperture actuation and metering, which is why manual exposure, manual focus and manual white balance are standard, and why deflicker passes in tools such as LRTimelapse are routine for day-to-night sequences.

Interval photography began as a scientific instrument rather than an aesthetic one. The German plant physiologist Wilhelm Pfeffer used sequences of timed photographs in the 1890s to make plant growth and tropism visible as motion, and Georges Melies is credited with using the technique cinematically around 1897 in a Paris street scene. In Britain, the naturalist F. Percy Smith produced pioneering time lapse studies of plants and small organisms for the Secrets of Nature series in the 1920s and 1930s, establishing the convention of using compressed time to reveal biological processes that unfold too slowly for direct observation. The American photographer John Ott spent decades from the 1930s onward refining motorized time lapse rigs for plant growth studies, contributing footage to Walt Disney productions including the 1956 film Secrets of Life and helping move the technique from laboratory demonstration to popular cinema. Time lapse became a narrative language in its own right with Godfrey Reggio's Koyaanisqatsi in 1982, shot largely by Ron Fricke, whose custom intervalometers and motion-control rigs demonstrated moving-camera time lapse at feature scale. The transition to digital removed the two historical constraints of film cost and limited magazine capacity, and once cameras shipped with built-in interval timers and inexpensive external intervalometers became common in the 2000s, the calculations that had been the province of specialist crews became an ordinary planning step for any photographer.