Timelapse planner

Plan — choose what to solve for: the clip length, the interval or the event duration. Durations can be typed as 2h, 90m, 1:30:00, 3d or plain seconds; intervals as 5, 15m or 1/2. The cards show the frames to shoot, the speed-up (how many seconds of real time each second of video covers), the card space at your file size, how many frames fit on the card and the batteries you’ll need. A table lists typical intervals for common subjects.

Shutter angle — the exposure for a target shutter angle at your interval (180° is the cine standard: half the interval), the ND filter that gets your metered exposure there, and the angle your own exposure gives. A strip of eight frames shows how much of each interval the shutter is open.

Day to night — pick a city (or a latitude, longitude and time zone), the date and the direction (sunset into night, or night into sunrise). The page finds sunset or sunrise and the three twilights, estimates how the light falls, and suggests the shutter and ISO every ten minutes at a fixed aperture: shutter first (up to the interval minus a second to write the file, or a longer limit you set), then ISO up to your highest. It flags where you run out, and how many ⅓-stop changes the ramp needs and how many frames apart.

The solver and storage are arithmetic. Card sizes are in GB as sold (10⁹ bytes).

Sun times and elevations come from the sun and moon planner's calculation (NOAA’s solar equations after Meeus), loaded from that tool.

The light ramp is a rule of thumb. Anchor illuminances are from Wikipedia’s "Illuminance" table: 400 lux at sunrise or sunset on a clear day, 3.4 lux at the dark limit of civil twilight (sun 6° down), and the night sky below −18° — 0.002 lux moonless and clear with airglow, 0.05–0.3 lux under a full moon (the page uses 0.15), 0.0001 lux moonless and overcast. In between, the light is assumed to change smoothly (log-linearly) with the sun’s elevation. Illuminance becomes an incident-light EV at ISO 100 with the calibration constant C = 250 (ISO 2720): E = 2.5 × 2^EV lux.

Battery counts compare frames with the CIPA shots-per-charge figure from your manual, and the duration with an hours-per-charge figure if you give one.

The ramp is a plan, not a meter. Clouds, city glow, the moon, a bright sky in the frame and snow all move the real exposure by stops. Keep metering, or use the camera’s own exposure smoothing or a bulb-ramping controller, and deflicker in post.

The light model is for a clear sky; the day side (before sunset) is fixed at bright daylight, so the first rows of an afternoon ramp are only indicative.

At high latitudes in summer, twilight may never end; the ramp stops where the sun stops falling.

Battery life varies widely with temperature, long-exposure noise reduction, stabilisation and the screen. Test before a long shoot.