An ND filter is a dark piece of glass that reduces the amount of light entering your camera without changing colors

ND stands for neutral density. It works like sunglasses for your camera lens — it makes everything darker so less light reaches the sensor. Unlike sunglasses that might tint the world yellow or brown, an ND filter keeps colors accurate while straightforward dimming the scene.

The main reason to use one is to let you shoot with settings you otherwise couldn't. If you're outside on a bright day and want to use a slow shutter speed (which blurs motion) or a wide aperture (which creates a blurry background), the sensor will capture too much light and your image will be overexposed — washed out and too bright. An ND filter solves this by blocking some of that light, so you can use the settings you want.

ND filters come in different strengths. A 2-stop filter blocks twice as much light as a 1-stop filter. A 10-stop filter blocks so much light that you can shoot in daylight with a shutter speed of several seconds, which is useful for blurring water or clouds in landscape photography.

Key Takeaways

  • An ND filter darkens your image without changing color, letting you use slower shutter speeds or wider apertures in bright conditions.
  • Photographers use ND filters to blur moving water, clouds, or people in daytime shots, which normally requires settings that would overexpose the image.
  • ND filters are measured in stops — a higher number blocks more light and lets you use even slower shutter speeds.
  • Variable ND filters adjust their strength by rotating, while fixed ND filters have one strength and don't rotate.

Why photographers use ND filters for motion blur

The most common use is to blur motion in daylight. If you're photographing a waterfall and want the water to look silky and smooth, you need a shutter speed of at least one second — usually longer. In bright sunlight, a one-second exposure will overexpose your image even at the smallest aperture and lowest ISO. An ND filter lets you shoot at that speed without the image washing out.

The same applies to clouds. A long exposure blurs clouds across the sky, creating a sense of movement and drama. Without an ND filter, you can only do this at sunrise or sunset when the light is already dim. With a 10-stop ND filter, you can shoot at 20 or 30 seconds in full daylight.

Video creators use ND filters for a different reason: to keep a consistent shutter speed while adjusting exposure. Video shutter speed is tied to frame rate — if you're shooting at 24 frames per second, your shutter should be around 1/48th of a second for natural motion. If the scene is too bright, you can't slow the shutter without breaking that rule. An ND filter lets you reduce exposure without changing shutter speed.

Fixed ND filters versus variable ND filters

A fixed ND filter has one strength — say, 6 stops — and you screw it onto your lens. It doesn't rotate or adjust. If you need a different strength, you swap it out for another filter. Fixed filters are cheaper, produce sharper images, and don't have moving parts that can fail.

A variable ND filter rotates to adjust its strength, usually from 2 stops to 8 stops or higher. You screw it on once and twist the ring to get the darkness you want. This is convenient on a shoot because you don't have to carry multiple filters or swap them constantly. The downside is that variable filters are more expensive, can introduce color shifts at extreme settings, and the rotating mechanism can wear out.

For most people starting out, a fixed 6-stop or 10-stop ND filter is the better choice. It's cheaper, more reliable, and you can always buy a second one if you need a different strength later.

How to measure ND filter strength

ND filters are labeled by stops or by a ratio. A 2-stop filter is also called ND4 (because it blocks 2 to the power of 2, or 4 times as much light). A 3-stop filter is ND8. A 10-stop filter is ND1024.

The stop number tells you how many stops of light the filter blocks. Each stop represents a halving or doubling of light. If you're shooting at f/2.8 and 1/1000th of a second in bright sun, and you add a 3-stop ND filter, you can now shoot at f/2.8 and 1/125th of a second (three stops slower) and get the same exposure.

When you're shopping, you'll see labels like ND4, ND8, ND64, or ND1000. The higher the number, the darker the filter and the longer the shutter speed you can use. For landscape and water photography, a 6-stop (ND64) or 10-stop (ND1024) filter covers most situations.

What to watch for when buying an ND filter

The most important thing is the size. ND filters screw onto the front of your lens, and they come in sizes like 52mm, 58mm, 67mm, or 77mm. You need to match your lens diameter. You can find this number printed on the front of your lens or in the manual.

If you have multiple lenses with different diameters, you can buy a larger filter and use step-up rings to attach it to smaller lenses. This is cheaper than buying separate filters for each lens.

Quality matters more with ND filters than with some other accessories because a cheap filter can introduce color shifts or reduce sharpness. Brands like B+W, Hoya, and Lee make reliable filters. You don't need the most expensive option, but avoid the cheapest filters on discount sites — they often have visible color casts that ruin your images.

ND filters for video versus photography

Video creators rely on ND filters more than photographers do because video shutter speed is locked to frame rate. If you're shooting 24fps video outdoors in sunlight, your shutter speed must be around 1/48th of a second. If the scene is too bright, you can't slow the shutter to darken the image — you have to use an ND filter instead.

Photographers have more flexibility. You can adjust aperture, ISO, and shutter speed independently. An ND filter is optional for most photography — you use it when you specifically want motion blur or a shallow depth of field in bright conditions. For video, it's often essential.

Video creators often use larger, higher-quality ND filters because the image quality matters more when you're recording continuously. A slight color shift in a still photo might go unnoticed, but in video it's visible throughout the entire clip.

Common mistakes when using ND filters

The biggest mistake is buying the wrong size. Check your lens diameter before ordering. If you buy a 67mm filter for a 52mm lens, it won't fit.

Another common error is forgetting to adjust your exposure settings after putting on the filter. If you're used to shooting at 1/500th of a second and you add a 6-stop ND filter, you need to slow your shutter to around 1/8th of a second to maintain the same exposure. Many people screw on the filter, take a shot, and wonder why the image is too dark — they forgot to adjust.

Some photographers also use ND filters in situations where they're not needed. If you're shooting indoors or at sunset, the light is already dim enough. An ND filter just makes you use a slower shutter speed than necessary, which increases the risk of camera shake and blurry images.

Frequently Asked Questions

Do I need an ND filter for my camera?

Only if you want to shoot with a slow shutter speed or wide aperture in bright daylight. If you're happy with your current photos or you mostly shoot indoors or at sunset, you don't need one. They're optional for photography but more essential for video.

Can I use an ND filter on any lens?

Yes, as long as you buy the correct size for your lens diameter. The diameter is printed on the front of the lens or in the manual. If your lenses have different diameters, you can buy one larger filter and use step-up rings to fit it on smaller lenses.

What's the difference between a 6-stop and 10-stop ND filter?

A 10-stop filter blocks more light, so it lets you use a slower shutter speed. A 6-stop filter is enough for most water and cloud photography. A 10-stop filter is better if you want to blur clouds or people significantly in bright daylight, but it's harder to focus through because the image is very dark.

Will an ND filter make my images look worse?

A good-quality ND filter has no visible effect on image quality. A cheap filter can introduce a slight color shift or reduce sharpness. Stick with reputable brands like B+W, Hoya, or Lee, and avoid the cheapest options.

Can I stack multiple ND filters together?

Yes, you can screw one ND filter onto another. A 3-stop filter plus a 6-stop filter gives you 9 stops total. This is useful if you need a strength you don't own, but stacking can introduce slight color shifts and reduce sharpness, so it's better to buy the exact strength you need.