ND filter and shutter speed calculator
Cinematic motion blur is a shutter speed problem, and daylight is what stops you reaching it. This works out the filter.
Researched from published specifications and verified owner reviews · updated 2026
The short answer
The 180 degree shutter rule sets shutter speed to 1 divided by twice the frame rate, so 1/50 second at 24 fps and 1/60 at 30 fps. On a clear sunny day at f/2.8 and ISO 100 that usually requires an ND32 or ND64 filter. Overcast typically needs ND8 or ND16, and golden hour often needs none.
The difference between drone footage that looks like video and drone footage that looks like film is almost entirely shutter speed. Leave the camera on automatic and it will pick 1/1000 second on a bright day, which freezes every frame and turns smooth movement into a stuttering, strobed mess once the clip is played back. The fix is to force the shutter down to roughly twice the frame rate, and the only way to do that in daylight is to put a neutral density filter in front of the lens.
Freewell
Freewell All Day 6-pack ND filters (Mini 3 series)
ND8, ND16, ND32, ND64, CPL and more
Six densities in one magnetic set covers everything from heavy overcast to open desert, which is the whole point: light changes through a shoot and one filter does not.
Prices move constantly. We earn a commission if you buy through these links, at no extra cost to you.
Below, put in the frame rate you are shooting, the light you are in, and the aperture and ISO the aircraft is using, and the calculator returns the shutter speed the rule demands, the shutter your exposure would otherwise land on, and how many stops of ND close the gap.
Exposure
ND filter strength
Exposure values are the standard sunny-16 family, which is the reference photographers have used for a century and is accurate enough to pick a filter.
Exposure values are a standard reference, not a light meter reading. Snow, water, dark forest and a bright sky in frame all shift the real exposure by a stop or more, so treat the result as the filter to fit first and then trust the aircraft's histogram. Shooting a flat or log profile changes where you want the exposure to sit, which is covered in the log profile guide.
Why 180 degrees is the number
Film cameras exposed each frame through a rotating disc with a slice cut out of it. A 180 degree opening meant the film was exposed for half the time each frame occupied, so at 24 frames per second the exposure was 1/48 of a second. A century of cinema was shot that way, and audiences learned to read that specific amount of per-frame motion blur as normal.
Deviate and the footage tells on you. A much faster shutter, say 1/1000, freezes each frame so completely that panning becomes a sequence of sharp stills rather than continuous movement, which reads as stuttering or strobing. That effect gets used deliberately in action sequences, and it is an effect, not a default. A much slower shutter smears the frame, which is why a 270 degree setting is sometimes used for a dreamy look and almost never for anything else.
On a drone the stakes are higher than on the ground, because aerial footage is dominated by continuous smooth movement. A slow forward push over a landscape is exactly the shot where a strobed shutter is most visible.
ND filter strengths and what each one removes
| Filter | Stops removed | Light passed | Typical use at 24 fps, f/2.8, ISO 100 |
|---|---|---|---|
| ND4 | 2 | 1/4 | Heavy overcast, late afternoon |
| ND8 | 3 | 1/8 | Overcast, no shadows |
| ND16 | 4 | 1/16 | Bright overcast, soft shadows |
| ND32 | 5 | 1/32 | Clear sunny day, the workhorse |
| ND64 | 6 | 1/64 | Strong midday sun |
| ND128 | 7 | 1/128 | Sun on snow, sand or open water |
| ND256 | 8 | 1/256 | Extreme, or a much faster frame rate |
The naming is a source of confusion. ND8 means one eighth of the light gets through, which is three stops. Some manufacturers instead label filters by stops, so an "ND 3" on one brand is the same as an "ND8" on another. Check which convention you are buying into, and note that the doubling means the numbers grow quickly: each step up the ladder is one stop.
The full grid including higher frame rates is on the ND filter chart, and the matching shutter figures for every frame rate are on the shutter speed chart.
What to carry
A six-filter set covers the whole range and costs less than a single premium filter, which is why most pilots start there. A Freewell All Day 6-pack ND filters (Mini 3 series) ($40) set for the Mini series or a K&F Concept ND/PL filter set (Air 3S) ($38) ND and polariser set for the Air 3S will handle almost any condition you fly in.
The alternative is a variable ND such as the Freewell 3-7 stop variable ND (Mavic 4 Pro) ($70), which covers a range in one filter and can be dialled between shots without landing. That convenience is real, and so are the trade-offs: a slight colour cast toward the ends of the range, and a dark cross pattern across the frame if you rotate past the marked limits. Neither is a reason to avoid one, but both are reasons to test yours on the ground before you rely on it. The comparison is written up at fixed versus variable ND, and the full roundup at best ND filters for drones.
Two mistakes worth avoiding
Do not stack filters. Two filters in front of a small drone lens usually vignettes the corners and always adds surfaces for flare. If you need more density, buy the darker filter.
Do not use ND for mapping or for stills. There is no motion blur requirement in a photograph, and on a mapping mission a slow shutter is actively harmful because aircraft motion during the exposure smears detail you paid altitude for. Shoot the fastest shutter the light allows and use the GSD calculator to check that motion blur is not eating your resolution.
Getting the rest of the exposure right
Filters solve the shutter. The remaining decisions are frame rate, ISO, white balance and colour profile, and they are covered in drone camera settings for video. If you are shooting a flat profile, read log versus normal first, because log changes where correct exposure sits and a lot of muddy drone footage is simply log shot at the exposure you would use for a normal profile. For the shot vocabulary itself, see cinematic drone moves.
Questions people ask
+ What is the 180 degree shutter rule?
Set shutter speed to roughly one divided by twice the frame rate. At 24 fps that is 1/48, usually rounded to 1/50, and at 30 fps it is 1/60. The rule comes from film cameras with a half-open rotating shutter, and it produces the amount of motion blur per frame that viewers read as natural. Faster shutters look stuttery and strobed, slower shutters look smeared.
+ Which ND filter do I need on a bright day?
On a clear sunny day at 24 fps and ISO 100, an aperture around f/2.8 usually needs ND32 or ND64 to reach 1/50 second. Overcast conditions typically need ND8 or ND16, and golden hour often needs nothing at all. Because conditions change through a shoot, most drone pilots carry a set rather than a single filter and change as the light does.
+ Do I need ND filters for photos or only for video?
Mostly video. Stills have no motion blur requirement, so a fast shutter is fine and usually better because it eliminates any blur from aircraft movement. ND filters help stills only when you deliberately want a long exposure, for example to smooth water, and that is difficult from a hovering aircraft. Mapping is the same: shoot the fastest shutter the light allows.
+ Is a variable ND better than a set of fixed filters?
A variable ND covers a range in one filter and can be adjusted between shots, which is faster in changing light. The trade is optical: variable filters can introduce a colour cast and, pushed past their marked range, a dark cross pattern across the frame. Fixed filters are cleaner and cheaper per stop, but changing them means landing. Most working pilots own both.
+ Should I use a polariser as well?
A circular polariser cuts reflections off water, glass and wet foliage and deepens sky contrast, which is genuinely useful over lakes, greenhouses and shiny roofs. It also costs one to two stops of light, so it doubles as light ND. The catch on a drone is that polarisation depends on angle to the sun, so as the aircraft yaws the sky darkens and lightens unevenly across a rotating shot.
+ What if I cannot get a dark enough filter?
Close the aperture if your aircraft has one, which most 1-inch and larger drone cameras do, and drop ISO to its base value. If the shutter is still too fast, accept it. A shutter of 1/100 at 24 fps looks slightly crisper than ideal and almost nobody notices in a wide aerial shot, whereas a badly exposed clip is a real problem. Do not stack more than two filters, since that risks vignetting.
