Neutral Density Filters Explained! When and How to Use Them for Photography and Videography

What are neutral density (ND) filters and how do you use them? Today I’ll explain what ND filters are, how they differ from other filters such as polarizers, and when to use them when shooting photos or videos.

What is an ND Filter?

An ND filter goes on the front of your camera lens and it blocks light from entering your camera frame. If you are using an interchangeable lens camera such as a DSLR or mirrorless camera, the ND filter is circular and size-specific depending on the filter size of your lens. ND filters also exist for other cameras such as drones and GoPros, but they are very size-specific, so you’ll have to buy them from vendors that sell filters made exactly for the product that you are using. ND filters come in a variety of strengths, such as ND 8, ND 16, and ND 32. The higher the number, the stronger the ND filter and the more light gets blocked out.

There is also a variable neutral density filter (VND). This filter is circular and changes power as the filter is rotated. It’s a convenient way to get multiple ND filters in one, but the only catch is that you have to be extra vigilant while shooting and change the ND filter according to the light conditions.

Why use an ND filter?

ND filters are typically used for both photography and videography, or filmmaking.

For Photography

In photography, ND filters can help you slow down motion in bright conditions for shooting long exposure photography. Think a smooth flowing waterfall in broad daylight, or cars driving on a road that gets blurred out. Typically, you can only achieve this type of photography in dark conditions after the sun goes down. However, you can use an ND filter to trick your camera into thinking broad daylight is darker than it really is. This helps you shoot at low shutter speeds in bright conditions. There’s also another type of ND filter out there called the graduated ND filter. This filter is half regular (see-through), and half darkened. The best use of this filter is when shooting a landscape where the sky is brighter than the foreground. A graduated ND helps balance out the light in the scene.

: No ND filter.

: With ND filter.

: With ND filter.

For Filmmaking

For videography, ND filters also help block out light to blur your video footage. You might be wondering, “why would I want blurry video footage?” Well, it depends on what kind of video you are trying to film. If you want a cinematic, movie-like film, your video should have a slight blur when filming a fast-moving subject, such as a waterfall, or an athlete running fast. If you don’t have this motion blur and are shooting at a high shutter speed, like 1/8000 sec, your subject might appear like it is moving unnaturally fast. It’s a subtle thing, but the trained video eye will notice this irregularity.

To avoid this unnatural movement, video camera settings should have a shutter speed that is double your frame rate. Typically, videos are shot in either 24 frames per second or 30 frames per second. That would require your shutter speed to be at either 1/48 sec or 1/60/sec. Doing so will usually cause your image to seem blown out, especially if shooting in bright lighting conditions. This is when ND filters help to block out light so that you can maintain a low shutter speed while shooting video.

What if I shoot video in auto settings?

Some cameras out there such as drones and GoPros offer ND filters, but the cameras are designed in a way that makes it tough to adjust settings or ND filters while filming. Specifically, the GoPro never shows you your exact settings (shutter speed, ISO, aperture), or tools like a histogram or zebra patterns while shooting. This makes it challenging to appropriately film cinematic footage. However, if you leave the camera on auto settings, ND filters can still be helpful if you are shooting in ultra-bright conditions, such as a sunny day in the tropics. It works like this: the ND filter darkens your image to a certain degree, and this will lower your auto shutter speed. It probably won’t get exactly down to cinematic settings, but this can help your image from getting blown out.

How is an ND filter different than a polarizer?

Polarizers and ND filters are similar in that they are filters that go in front of camera lenses. They also block light, but the difference is the type of light they block, and how that impacts your resulting shot. ND filters block light in general and only affect the brightness of your image. On the other hand, polarizers block light that is reflected off of surfaces, such as water or glass. The resulting impact is on your image color, and polarizers can help saturate colors in your image.

Best ND filters for photo and video?

Due to their different shooting styles, you want specific ND filters for shooting photography versus videography. When shooting video, you typically want a variable ND because your camera settings stay relatively stable, so you need to adjust the amount of light hitting your camera’s sensor. But if you’re shooting with a camera like a drone or GoPro, VNDs usually are not an option. PolarPro is the leading brand for high quality ND filters for drones and GoPros.

However, photography typically does not call for super-specific camera settings, so static ND filters are best. If you’re serious about landscape photography, consider getting an entire kit made by brands such as Lee, Cokin, and Formatt HiTech. They can be pricey, especially if you go for glass filters (the best quality). So if you’re looking to save some money, go for resin filters instead. They cost less and also are harder to scratch or damage if you drop them. I went the resin route via Formatt HiTech and have been very happy with their filters. Just note that these kits involve buying a filter holder, a size-specific ring to attach to your camera lens, and filters. It might sound like a lot, but these kits are usually more flexible than having to buy filters for each lens that you own.