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Shutter Speed & ND Calculator
Use an exposure measurement rather than a weather label to plan a neutral-density filter. This is a creative exposure tool, not flight or camera-operating advice.
Start with a shutter angle
Exposure time = shutter angle ÷ (360 × frame rate). At 30 fps and 180°, each frame is exposed for 1/60 second. At 24 fps and the same angle, it is 1/48 second. A camera with discrete shutter settings may require the nearest supported choice.
Worked example: four stops
Suppose correct exposure at your fixed aperture and ISO requires 1/960 second, while your desired exposure time is 1/60 second. The desired exposure lasts sixteen times longer. Reducing light by a factor of sixteen is four stops: log₂(16) = 4. That corresponds to an ND16 factor designation.
Keep aperture and ISO consistent
The comparison only works when your meter reading and desired exposure use the same aperture and ISO under the same light. If auto ISO changes during the comparison, or the light changes as you turn, your result is no longer the same exposure problem.
Why this is not a sunny-day filter table
Cloud cover, reflections, altitude, lens aperture and camera settings can change the necessary filtration. A fixed rule such as one filter for every sunny day is not a measurement. Use your camera histogram and highlight warnings, and check the actual scene.
Motion blur is a choice
A 180° shutter is a familiar creative starting point, not a rule that every shot must obey. Faster exposures can suit sharp action frames; slower exposures can increase blur. ND filters only reduce light. They cannot fix insufficient light, unstable movement or an unsuitable shutter choice.
Frequently asked questions
What does a zero-stop result mean?
The requested exposure does not require reducing light relative to the entered meter reading. An ND filter cannot add the light needed for a shorter exposure.
Can I choose the next stronger filter?
The tool shows the mathematical factor. With a fixed filter set, compensate deliberately and re-meter rather than assuming the nearest label gives the right exposure.
Formulas and examples reviewed on 26 October 2026. Planning estimates, not measurements of your footage or equipment.