Long Exposure & ND Calculator

Long exposure, from the first calculation to the final frame.

A focused ND / long-exposure calculator for landscape and long-exposure shooters — fast, accurate, and built around the one thing the free apps get wrong: a timer that actually holds.

FREE — everything you need to shoot • ND exposure calculator: pick your base shutter and ND filter, get the exact long-exposure time (T = base × 2^stops). • Every ND, by name or stops — ND2 to ND32000, density or stop labels, all mapped to exact stops. • Full 1/3-stop shutter ladder (1/8000 … 30s) — including the in-between values other apps drop (1/10, 1/40, 1/160, 1/200…), plus custom / Bulb input. • In-app countdown timer with a finish chime. • Red-light night mode to protect your dark adaptation in the field.

PRO — $1.99 once, no subscription • Film reciprocity correction — the real differentiator. Adds the extra exposure film needs in long exposures, based on manufacturer/reference data (Ilford HP5+/FP4+/Delta, Kodak T-Max/Tri-X, Fomapan). Values are approximate (≈) and can vary by film batch and temperature — verify with a test frame for critical work. Stop wasting frames to reciprocity failure. • Reliable finish alert — a local notification fires the moment your exposure ends, even with the screen off or the app closed. The competitors' #1 complaint, solved. • Filter stacking — combine multiple NDs, stops add automatically. • Saved gear presets — keep your real kit (Little Stopper, K&F ND1000, a lens + filter combo). • Motion-blur preview — an illustrative hint of how silky the water and clouds get as you change the time.

ACCURATE BY DESIGN Every ND mapping and shutter value is verified against manufacturer and reference data — not guessed. The exposure-time math is exact (canonical unit = stops). Film-reciprocity values are reference approximations (≈), not exact.

PRIVATE & LOCAL No account, no cloud, no ads, no tracking. One-time purchase, restored on any device with your Apple ID.

Available in English and 简体中文.