An ND (neutral density) filter cuts the light reaching the sensor so you can use a slower shutter speed in daylight. For silky waterfalls, use about ND8 to ND64 to reach 1/4 to 2 seconds. For glassy oceans and streaking clouds, use ND1000 (about 10 stops) for exposures of 10 seconds or more. You don't need ND at night, for astrophotography or indoors, because the light is already low.
The shutter speed math
Each stop doubles the exposure time. With your settings locked (base ISO, aperture), measure the exposure without the filter, then multiply:
| Filter | Stops | 1/125 s becomes |
|---|---|---|
| ND8 | 3 | 1/15 s |
| ND16 | 4 | 1/8 s |
| ND64 | 6 | 1/2 s |
| ND128 | 7 | 1 s |
| ND1000 | 10 | about 8 s |
For a full guide to the numbers, see ND filter numbers explained.
Waterfalls and rivers
- Shutter: 1/4 s keeps some texture; 1 to 2 s gives a smooth, milky flow.
- Filter: ND8 to ND64, depending on light. In shade, you may not need one at all.
- Settings: base ISO, f/8 to f/11, manual focus, tripod, 2-second self-timer or remote.
Ocean, lakes and clouds
- Shutter: 10 to 60 seconds or more flattens waves and turns moving clouds into streaks.
- Filter: ND1000 (10 stops). In bright sun, some photographers stack an ND64 and ND16.
- Use Bulb or Time mode for exposures longer than 30 seconds, and check the histogram since auto exposure may not meter accurately through a strong ND.
Portraits in bright light
ND isn't only for slow shutter speeds. It lets you shoot at f/1.4 to f/2 in midday sun for soft backgrounds without hitting your camera's top shutter speed.
When you don't need ND
- Night and city lights: it's already dark enough for long exposures. Use a tripod.
- Astrophotography: you want every bit of light. Never use ND for stars.
- Indoors: too dark already, unless you're intentionally blurring motion under bright studio lights.
- Underwater: light falls off quickly underwater; ND is rarely useful.
Vignetting
Dark corners can appear when filters are stacked, when a thick filter ring sits on a wide-angle lens, or with variable ND filters set near maximum. Use slim filters, avoid stacking on wide lenses, and crop if needed. More on that in variable ND filters.
ND filters on drones
Drone ND filters are mainly for video motion blur (the 180-degree rule: shutter speed about double the frame rate). For example, 4K at 30fps wants about 1/60 s. On f/1.8 drone cameras like the Air 3S and Mini 5 Pro, that usually means ND128 in full sun and ND32 under bright cloud. Long still exposures from a hovering drone are limited: wind and small movements blur multi-second shots. DJI's ND sets for the Air 3S and Mini 5 Pro include ND8, ND32 and ND128. See which ND filter for drones.
Tips
- Focus and compose first, then attach the filter. Strong NDs make the viewfinder very dark.
- Shoot RAW. Strong NDs can add a color cast you'll correct later.
- Turn on long exposure noise reduction if your camera has it.
- Keep the filter clean. Smudges show up in long exposures.
For the basics, read what ND filters do.
Related guides
- What do ND filters do? ND filters explained for video
- Best ND filters for drones and cameras: DJI vs K&F, H&Y, JJC and other brands
- Variable ND filters vs other ND types: are they worth it?
- Which ND filters for the DJI Air 3S? Settings guide
- Which ND filters for the DJI Mini 5 Pro? Settings guide
- ND filter numbers and stops explained (ND8, ND16, ND32, ND64)
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