ND filter density chart
Density, stops, and the light each one is actually for, in one table.
Researched from published specifications and verified owner reviews · updated 2026
The short answer
ND4 is two stops, ND8 three, ND16 four, ND32 five, ND64 six and ND1000 ten. For 24 or 30 fps video, overcast conditions usually call for ND8 or ND16, hazy sun for ND16 or ND32, and open bright sun for ND32 or ND64. The goal is a shutter speed close to double the frame rate, which is 1/50 second at 24 fps, because that is what produces natural motion blur.
An ND filter is sunglasses for a camera that cannot squint. Drone cameras generally have a fixed aperture, so the only exposure controls available are ISO, which should already be at base, and shutter speed, which is the one setting you are trying to hold still. In daylight that pushes the shutter to 1/1000 second or faster, which freezes motion and produces the stuttery, over-crisp look that reads instantly as amateur drone footage.
Freewell
Freewell All Day 6-pack ND filters (Mini 3 series)
ND8, ND16, ND32, ND64, CPL and more
Six densities from light overcast through open desert, on a magnetic mount so a filter change does not mean re-balancing the gimbal each time. Buying a set rather than one or two filters is the right call because the density you need changes with the light within a single session, and being one stop short is as useless as having nothing.
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Density, factor and stops
| Filter | Light passed | Stops reduced | Typical use |
|---|---|---|---|
| ND2 | 1/2 | 1 | Rarely useful alone. Deep overcast, dusk. |
| ND4 | 1/4 | 2 | Golden hour, heavy overcast, shaded valleys. |
| ND8 | 1/8 | 3 | Overcast daylight. The most-used low density. |
| ND16 | 1/16 | 4 | Bright overcast or hazy sun. |
| ND32 | 1/32 | 5 | Open sun, mixed cloud. The workhorse density. |
| ND64 | 1/64 | 6 | Hard midday sun, sand, snow, water. |
| ND128 | 1/128 | 7 | Extreme reflected light, high altitude snow. |
| ND256 | 1/256 | 8 | Specialist. Rarely needed on a drone. |
| ND1000 | 1/1000 | 10 | Long-exposure stills, not video. |
Density by condition, for 24 to 30 fps
| Conditions | Start with | If the shutter is still too fast |
|---|---|---|
| Golden hour, sun low and soft | None or ND4 | ND8 |
| Heavy overcast, flat grey sky | ND4 or ND8 | ND16 |
| Bright overcast | ND16 | ND32 |
| Hazy sun | ND16 or ND32 | ND64 |
| Open bright sun, green landscape | ND32 | ND64 |
| Midday sun over water, sand or snow | ND64 | ND128 |
Use the table to pick a starting filter, then check the shutter reading rather than trusting it. The reflectivity of the scene moves the answer by a stop or more, which is why the same filter that is correct over a forest is wrong over a beach on the same afternoon. The ND filter and shutter calculator does the arithmetic for a specific frame rate and light level.
What you are aiming at
The target is a shutter speed close to double the frame rate, which comes from the 180 degree shutter convention in film. At 24 fps that means 1/48 second, and since cameras rarely offer 1/48 the practical setting is 1/50. At 30 fps the target is 1/60, and at 60 fps it is 1/120.
| Frame rate | Ideal shutter | Practical setting |
|---|---|---|
| 24 fps | 1/48 | 1/50 |
| 25 fps | 1/50 | 1/50 |
| 30 fps | 1/60 | 1/60 |
| 50 fps | 1/100 | 1/100 |
| 60 fps | 1/120 | 1/120 |
| 120 fps | 1/240 | 1/250 |
Note the consequence for high frame rates: shooting 60 fps needs a faster shutter, which means less filtration, which means a lighter filter than the same light would need at 24 fps. People who switch frame rate mid-session and keep the same filter get this wrong constantly. The full table is on the shutter speed chart.
When to break the rule
The 180 degree convention is a convention rather than a law, and there are three situations where ignoring it is correct.
Fast motion you intend to slow down. Footage shot at high frame rate for slow motion often looks better slightly crisper than the convention suggests, because the motion blur is stretched along with the time.
Detail work. Inspection footage where the deliverable is evidence rather than atmosphere should be sharp. Freeze the motion, ignore the aesthetics, and get the crack in focus. That is the approach on the roof inspection workflow.
Very low light. At dusk you may not be able to reach the target shutter without raising ISO past where the sensor holds together. A slightly faster shutter and clean footage beats correct motion blur and noise you cannot grade out.
Fixed set or variable filter
A fixed set gives you discrete densities in clean single-element glass. A variable ND covers a range in one filter and adjusts by rotation, which is fast in changing light and costs you a colour cast toward the ends of the range and a visible cross pattern if you push past the marked limits. A Freewell 3-7 stop variable ND (Mavic 4 Pro) ($70) covering three to seven stops replaces most of a fixed set for a flagship aircraft.
Neither is wrong. Fixed sets suit consistent light and careful shooting; variable suits fast changes and single-flight sessions. The argument in full is on fixed versus variable ND, and the product comparison is on best ND filters for drones.
Fitting filters without causing problems
Buy filters cut for your exact aircraft. Gimbals are balanced for a specific mass and a filter designed for a different model can load the roll axis enough to produce correction artefacts. Mini-class gimbals are the fussiest, which is why a K&F Concept ND/PL filter set (Mini 5 Pro) ($37) exists as a separate product rather than a universal set.
Fit and remove with the aircraft powered down. Forcing a filter onto a live gimbal is how mounts get damaged, and it is a repair that costs more than every filter you own.
Weigh the result if you are near 250 g. A filter is a few grams and it stacks with guards and strobes. See the weight and registration calculator.
Keep the glass clean. A smeared ND produces veiling flare against a bright sky that no grade recovers. A cloth in the case is the cheapest optical upgrade available.
Everything here is researched from published specifications and photographic first principles rather than hands-on testing, and exposure is scene-dependent, so treat these as starting points and check the histogram.
Questions people ask
+ Which ND filter should I use in bright sun?
For 24 or 30 fps video in open bright sunlight, ND32 or ND64 is the usual answer, which is five or six stops of light reduction. Overcast conditions usually need ND8 or ND16, and golden hour often needs ND4 or no filter at all. The exact density depends on your base ISO and the reflectivity of the scene, so check the shutter reading rather than trusting the table blindly.
+ What does the number on an ND filter mean?
It is the factor by which the light is divided. ND4 passes a quarter of the light, which is two stops. ND8 passes an eighth, three stops. ND16 is four stops, ND32 five, ND64 six and ND1000 ten. The numbers double every stop, which is why the useful set is a doubling sequence rather than an even spread.
+ Why does a drone need ND filters when a camera does not?
Because a drone camera generally has a fixed aperture. A ground camera can stop down to f/11 or f/16 to control light, at some cost in sharpness. A drone with a fixed f/1.7 or f/2.8 lens has no such option, so the only exposure controls left are ISO, which is already at base, and shutter speed, which is exactly the setting you are trying to hold constant.
+ Do I need a polariser as well?
Only sometimes, and combined ND and polariser filters exist for exactly that reason. A polariser cuts glare off water, glass and wet foliage and deepens a blue sky, at a cost of roughly one to two stops and an uneven sky when shooting wide across the polarisation angle. If you fly over water or glass regularly it earns its place. Otherwise a plain ND is optically simpler.
+ Can I stack ND filters?
Physically yes on some mounts, practically no. Stacking adds weight to a gimbal designed for one filter, introduces reflections between glass surfaces, and risks vignetting at wide angles. Buy the density you need rather than combining two, which is why filter sets are sold as a range rather than as a base filter plus adders.
+ Does an ND filter change the registration weight?
It adds a few grams, which is negligible on its own and is not negligible if you are close to the 250 g threshold. Filters, guards, strobes and an extended pack stack together, and takeoff weight is measured with everything fitted. Run the total on the weight and registration calculator if you are anywhere near the line.
