Plan a time-lapse: frames, intervals and playback length
Convert an hour of capture into a short clip, distinguish capture interval from playback frame rate, and check whether the first frame is at time zero.
Method
Time-lapse compresses a long event by capturing still frames less often than they will be played. Capture interval tells you how long to wait between images; playback frame rate tells you how many saved images the finished video displays each second. These are separate controls. Changing playback rate does not create missing source frames or extend the event that was recorded.
Put capture duration and interval in the same time unit. Under the calculator’s convention, the first frame arrives after one full interval, so the frame count is the whole number of intervals that fit. Divide that count by playback frames per second to obtain seconds of video. State this counting convention explicitly when comparing camera settings or an existing image sequence.
Suppose you capture for 60 minutes at a five-second interval. The duration is 3600 seconds, and 3600 ÷ 5 gives 720 complete intervals and therefore 720 frames. At 30 fps, the video lasts 720 ÷ 30 = 24 seconds. The illustrative chart compares this with the same 720 frames played at 24 fps, which lasts 30 seconds.
View data
- At 30 fps
- 24 s 720 / 30
- At 24 fps
- 30 s 720 / 24
Worked example
Suppose you capture for 60 minutes at a five-second interval. The duration is 3600 seconds, and 3600 ÷ 5 gives 720 complete intervals and therefore 720 frames. At 30 fps, the video lasts 720 ÷ 30 = 24 seconds. The illustrative chart compares this with the same 720 frames played at 24 fps, which lasts 30 seconds.
If your camera captures immediately at time zero and also includes the last endpoint, this exact-divisibility example has 721 frames instead of 720. At 30 fps that adds one thirtieth of a second. For a duration that does not contain a whole number of intervals, inspect the actual capture schedule rather than rounding the frame count up and inventing a capture outside the planned time.
60 × 60 / 5 = 720 frames
720 / 30 = 24 s
720 / 24 = 30 s
Camera implementations differ about start delay, endpoints, exposure overlap and interval timing. Long exposures or slow storage can reduce the number of frames actually captured. The model excludes dropped frames, pauses and variable playback rate. Check a short test sequence and its real file count before recording a long event. Use the video-size calculator separately to estimate storage from a chosen bitrate.
View data
- Capture seconds
- 60 × 60 = 3600 s
- Count frames
- 3600 / 5 = 720
- Playback seconds
- 720 / 30 = 24 s
Checks and limits
Camera implementations differ about start delay, endpoints, exposure overlap and interval timing. Long exposures or slow storage can reduce the number of frames actually captured. The model excludes dropped frames, pauses and variable playback rate. Check a short test sequence and its real file count before recording a long event. Use the video-size calculator separately to estimate storage from a chosen bitrate.
Related calculators
Sources: OpenStax — decimal operations · Nikon Z 8 Reference Guide — Time-Lapse Video