Which ND filters do I use and when? Strengths, chart and practical tips
ND8, ND64 or ND1000? NiSi Ambassador and photography tutor Alexander Müller shows you which ND filter works in sunshine, under clouds and for flowing water. You also get a chart with every strength and exposure time plus the right camera settings.
Photo: Alexander Müller · Rock arch on Iceland’s south coast, long exposure with a NiSi ND filter
ND filters (neutral density filters) are mainly relevant when you want to achieve longer exposure times in bright light. The stronger the ND filter, the longer the exposure times you can get.
Weaker ND filters like the ND8 extend the exposure time by a factor of 8, while stronger ones like the ND1000 extend it by a factor of 1000. The right strength depends on your use case and the effect you're aiming for.
What is an ND filter?
ND stands for neutral density. An ND filter reduces the amount of light reaching the sensor evenly across the entire image without changing the colours. This lets you use long exposures or a wide aperture even in bright daylight without overexposing your photo.
What you need an ND filter on your camera for:
- Making motion visible: flowing water turns silky smooth, clouds streak across the sky and people disappear from busy squares.
- Wide aperture in sunshine: for portraits with shallow depth of field when your camera's fastest shutter speed is no longer fast enough.
- Filming in daylight: for natural motion blur you film with a shutter speed of roughly double the frame rate, i.e. 1/50 s at 25 frames per second. In sunshine that only works with an ND filter.
ND filters come as screw-in filters, as square filters for a filter holder and as magnetic filters. You'll find an overview of screw-in versions among our ND filters.
Which ND filter in sunshine, under clouds or in the forest?
Stronger ND filters are especially useful where there is a lot of light and long exposure times are desired. A waterfall in direct sunlight, for example, will at best show slight motion with an ND64, whereas with an ND1000 you can achieve exposures of several seconds.
In a shaded forest, an ND8 is often enough to reach shutter speeds that create pleasing motion.
To capture the effect of moving clouds during the day, an ND1000 is almost always necessary. If that's not enough, I combine the ND1000 with the ND8. The filter factors multiply, which gives me an effective ND8000.
Summed up as a quick guide for f/11 and ISO 100:
Swipe the table sideways
| Light | Flowing water | Moving clouds |
|---|---|---|
| Bright sunshine | ND1000 | ND1000 + ND8 |
| Overcast sky | ND64 | ND1000 |
| Shaded forest, dusk | ND8 | ND64 |
Guide values. How long you should expose for each effect is explained further down under exposure times.
Important with direct sunlight
An ND1000 is not a solar filter. If you want to shoot directly into the sun or capture a solar eclipse, you need a dedicated solar filter such as the NiSi Solar Filter ND100000 with 16.6 stops. Find out more in our article How to photograph a solar eclipse safely.
ND8, ND64 or ND1000: which strength for what?
Personally, I'm a big fan of very long exposures in the minute range, because water surfaces become smooth, moving clouds become dynamic and people walking past are barely visible. That's why the ND1000 is my most used filter, followed by the ND64, which is certainly the most versatile filter if you don't only shoot in sunshine. The ND8 lets me extend exposure times a little in darker surroundings and, combined with the ND1000, creates an extremely strong ND filter.
ND8
3 stops · factor 8
Slightly longer exposures in the forest, in the shade and at dusk. Ideal for combining with the ND1000.
ND64
6 stops · factor 64
The most versatile filter if you don't only shoot in sunshine. Perfect for flowing water.
ND1000
10 stops · factor 1000
Exposures in the minute range: smooth water, moving clouds and deserted squares.
“The ND1000 is my most used filter, followed by the ND64.”
Alexander Müller, NiSi Ambassador
And in between? An ND16 or ND32 is particularly popular for filming in daylight. For long exposures in the landscape, ND8, ND64 and ND1000 cover most situations.
ND filter chart: strengths, stops and exposure times
The number after “ND” is the exposure factor. An ND8 only lets an eighth of the light through, so you expose eight times as long. Every doubling of the factor equals one stop. Some manufacturers state the optical density instead of the factor, such as ND 0.9 instead of ND8.
Swipe the table sideways
| Filter | Stops | Optical density | 1/125 s becomes | 1/30 s becomes | Typical use |
|---|---|---|---|---|---|
| ND2 | 1 | 0.3 | 1/60 s | 1/15 s | Fine-tuning the exposure |
| ND4 | 2 | 0.6 | 1/30 s | 1/8 s | Wide aperture in bright light |
| ND8Alexander's set | 3 | 0.9 | 1/15 s | 1/4 s | Forest, shade, dusk, combining |
| ND16 | 4 | 1.2 | 1/8 s | 1/2 s | Video in daylight |
| ND32 | 5 | 1.5 | 1/4 s | 1 s | Video, water under an overcast sky |
| ND64Alexander's set | 6 | 1.8 | 1/2 s | 2 s | Flowing water, all-rounder |
| ND128 | 7 | 2.1 | 1 s | 4 s | Water in bright light |
| ND256 | 8 | 2.4 | 2 s | 8 s | Water in sunshine |
| ND1000Alexander's set | 10 | 3.0 | 8 s | 30 s | Moving clouds, smooth water |
| ND8000 | 13 | 3.9 | approx. 1 min | approx. 4 min | ND1000 + ND8: clouds in bright sunshine |
| ND64000 | 16 | 4.8 | approx. 9 min | approx. 36 min | ND1000 + ND64: empty squares, exposures of several minutes |
Values rounded to your camera's usual shutter speed scale. The starting value is the exposure time measured without a filter. Strictly speaking, an ND1000 corresponds to a factor of 1,024.
What exposure times should I aim for?
Motion becomes visible when the exposure time is long enough for the subject to move during the shot. For fast-flowing water, as little as ¼ second is enough to show slight motion. For moving clouds, depending on their speed, several seconds to minutes are needed.
Here are some recommendations as a guideline:
f/11 · 8 s · ISO 100 · NiSi 15mm + True Color CPL + ND64
Flowing water
¼ second to 30 seconds
f/11 · 180 s · ISO 100 · NiSi V7 Landscape CPL + ND1000 & ND8 + GND8 Medium
Moving clouds
15 seconds to 3 minutes
f/8 · 240 s · ISO 100 · NiSi 15mm + V7 True Color CPL + ND1000 & ND64
Empty squares
30 seconds to 5 minutes
Which settings should I use?
- Aperture f/8 to f/11In general, for photos with a large depth of field I recommend using the lens's “sweet spot”, the aperture range where sharpness is optimal and depth of field is large, i.e. f/8 to f/11.
- Lowest ISO, auto offFor long exposures on a tripod, ISO should be set to the lowest value, usually ISO 100. Auto settings must be switched off.
- Focus first, then attach the filterEspecially with older cameras, autofocus barely works or doesn't work at all with strong ND filters. In that case, focus without the ND filter first and then switch to manual focus (MF), so the camera doesn't try to refocus when you take the shot.
- Calculate the exposure timeThe shutter speed is the variable that depends primarily on the available light, the aperture you've set and the ND filter. Newer cameras can meter correctly even through several ND filters. One method always works: measure and test the exposure time without a filter (for example in aperture priority), extend it by the filter factor and set this time manually.
- Over 30 seconds: BULB modeExposure times longer than 30 seconds can usually only be achieved in BULB mode. In this mode you can expose for minutes, either by holding down the shutter button, programming an external remote release or via the camera menu.
NiSi tip
Use a remote release or the self-timer on the tripod so nothing shakes. Our guide Long exposure during the day takes you step by step to your first long exposure.
Combining ND filters: how to calculate
If you stack two ND filters, the factors multiply and the stops add up:
ND1000 + ND8
ND8000
10 + 3 = 13 stops
ND1000 + ND64
ND64000
10 + 6 = 16 stops
ND64 + ND8
ND512
6 + 3 = 9 stops
An example: without a filter your camera meters 1/125 s. With the ND1000 and ND8 you expose for around 65 seconds, so just over a minute in BULB mode. If you want to expose even longer, go for the 100x100mm ND1000K filter with 20 stops.
What's in my backpack?
I own 100x100mm ND filters in the strengths ND8, ND64 and ND1000. In rare cases I even combine the ND1000 with the ND8 for an ND filter with an 8000-fold extension.
NiSi tip
The 100x100mm filters go into the holder of the NiSi V7 filter system, where you can also combine them with graduated filters. Prefer magnetic and without a holder? The JetMag Pro Landscape ND Kit contains the same three strengths ND8, ND64 and ND1000 plus a True Color CPL.
And what about ND Vario?
ND Vario screw-in filters are also a good option and offer a higher degree of flexibility. Especially for those who work with screw-in filters, they are a practical solution. I would definitely recommend the stronger versions here.
A variable ND filter covers several strengths steplessly, for example 1 to 5 stops, which makes it popular for filming. For exposures in the minute range, however, you still need a fixed ND1000.
Which filter system suits you?
All three strengths from Alexander's backpack are available in every NiSi system. What matters is how you prefer to work.
- Screw-in filtersCompact and quick, ideal for one lens or on the go.
- V7 square filters100mm system with holder, combinable with graduated and polarising filters.
- JetMag Pro magnetic filtersAttached in seconds and securely stacked.
Shop ND filters Discover the V7 filter system Discover JetMag Pro
Frequently asked questions about ND filters
What is an ND filter?
An ND filter (neutral density filter) reduces the amount of light evenly without changing colours. This lets you use longer exposures in daylight, for example to make water look smooth or clouds blurred, or shoot photos and video with a wide aperture.
Which ND filter for sunshine?
In bright sunshine you almost always need an ND1000 for visible motion. It gets you exposure times of several seconds. For moving clouds, combine the ND1000 with an ND8 to make an ND8000. In sunshine, an ND64 is at most enough for slightly dynamic water.
Which ND filters do you need?
Three strengths cover most situations: ND8, ND64 and ND1000. With them you can handle forests and dusk, flowing water under an overcast sky and long exposures in sunshine. If you want to start with one filter, the ND64 is the most versatile and the ND1000 is the right one for exposures in the minute range.
What do ND8, ND64 and ND1000 mean?
The number is the factor by which the exposure time is extended. ND8 equals 3 stops, ND64 6 stops and ND1000 10 stops. 1/125 second becomes about 1/15 second with an ND8, about 1/2 second with an ND64 and about 8 seconds with an ND1000.
ND64 or ND1000: which is better?
That depends on the light and the effect you want. The ND64 is the more versatile filter for flowing water under an overcast sky. The ND1000 is the choice for moving clouds, smooth water and deserted squares in daylight.
How do I calculate the exposure time with an ND filter?
Measure the exposure time without a filter, for example in aperture priority, and extend it by the filter factor. With an ND1000, 1/30 second becomes about 30 seconds. Set times over 30 seconds in BULB mode.
Can I combine ND filters?
Yes. The factors multiply and the stops add up. ND1000 and ND8 make an ND8000 with 13 stops, ND1000 and ND64 an ND64000 with 16 stops.
Do I need an ND filter for filming?
In daylight, usually yes. For natural-looking motion you film with a shutter speed of roughly double the frame rate, i.e. 1/50 second at 25 frames per second. In sunshine the image quickly becomes overexposed. An ND16 to ND64 or a variable ND filter compensates for this.
Can I shoot into the sun with an ND filter?
An ND1000 is not suitable for shooting directly into the sun or a solar eclipse. For that you need a dedicated solar filter such as the NiSi Solar Filter ND100000 with 16.6 stops. For sunsets in the landscape, on the other hand, you can use ND filters as normal.