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03.17.2020

Why You Should Use Neutral Density Filters

ND filters are like sunglasses for your camera, and work in much the same way, cutting down the amount of light coming in through the lens so you can use longer exposures to blur motion. Here’s how to use them.

Usually when you hear photographers complaining about light, they are talking about the lack of it. But, occasionally, the opposite is true, and there is actually too much light to create the kind of pictures you want.

The most common example of this is when you want to use a long shutter speed to create motion blur in the scene, but the light is too bright to let you do this with the apertures and ISO settings available. In this situation, we have to find another way to reduce the amount of light coming into the lens. We do that with a neutral density (or ND) filter.

  • Learn photography with Fujifilm, Reducing Noise in Low Light Images
  • Learn photography with Fujifilm, Reducing Noise in Low Light Images

An ND filter is essentially like a pair of sunglasses for your lens and is used in many of the same situations. On a bright day, you’re not likely to achieve a shutter speed longer than 1/30 sec at F22, ISO 200 – which is not long enough to significantly blur things like crowds of people, flowing water, or moving traffic. But fit a three-stop ND filter to the front of your lens, and that 1/30 sec shutter speed instantly becomes 1/4 sec. That’s more like it!

  • Learn photography with Fujifilm, Reducing Noise in Low Light Images
  • Learn photography with Fujifilm, Reducing Noise in Low Light Images

ND filters come in various strengths, but the most common are two stops, three stops, seven stops, and ten stops. Two- and three-stop filters are great for landscape photographers who just want to smooth out the ripples on the surface of water using a longer shutter speed. Seven- and ten-stop ND filters are good for giving a landscape an otherworldly look and feel. They can transform a 1/30 sec shutter speed into a 4 sec or 32 sec exposure, respectively. That can blur the movement of the clouds in the skies and transform water into a mist. It’s an eerie, ethereal look.

Neutral density filters are also great for cityscape photography, as the longer shutter speeds can make people moving through the streets disappear – they simply don’t stand still for long enough to register on camera.

Learn photography with Fujifilm, Shutter Speeds and Motion Blur

ND filters are reasonably easy to use with X Series mirrorless cameras. Although you won’t be able to see very well through a ten-stop ND, your camera can. You may have to focus manually when using one, as such low levels of light are not great for AF, but this is not a big problem as you’ll need to work on a tripod anyway with such long shutter speeds. It’s also a good idea to use manual exposure mode, so you can stay in control.

The way ND filters are labelled can cause some confusion, with different manufacturers adopting different naming conventions. Some are labelled with the number of stops of light that they eliminate, and others are described with a filter factor or optical density. Here’s a handy translation guide:

F-Stop Reduction Filter Factor Optical Density
2 4 0.6
3 8 0.9
7 128 2.1
10

1024 (sometimes called 1000)

3.0

When it comes to exposure, your camera’s TTL metering system should take the ND filter into account, although if you’re using a seven- or ten-stop filter and the shutter speed ends up as being several minutes, you may need to work this out yourself and use the camera’s B setting. Do this by metering without the filter in place, then double the shutter speed for each stop of ND light reduction. Or, consult this handy guide, which we’ve put together by doing the counting for you!

Shutter Speed Without Filter With Two-Stop ND With Three-Stop ND With Seven-Stop ND With Ten-Stop ND
1/250 1/60 1/30 1/2 4
1/125 1/30 1/15 1 8
1/60 1/15 1/8 2 16
1/30 1/8 1/4 4 32
1/15 1/4 1/2 8 64

There is often some experimentation involved with using ND filters, so don’t be afraid to bracket your exposures. Also note that some brands of ND filter may not filter every wavelength of light equally, which can give rise to a color cast. Your camera’s auto white balance should sort this out, but if you like to shoot with white balance presets, you might notice they don’t look quite the same. Try making a manual preset or shooting RAW and setting white balance retrospectively.

As well as lengthening exposures, ND filters can help you maximize your lens’s image quality. You’ll be able to use the long shutter speed you want without resorting to your lens’s smallest aperture, which may not give the desired depth-of-field or image quality (something called diffraction kicks in at small apertures, which can slightly take the edge off optical sharpness).

Built-In Neutral Density Filters

If you’re shooting with an X100 series camera, you may be interested to know that this has a built-in three-stop ND filter that’s designed to help you shoot with wide apertures in bright conditions. You can access SHOOTING SETTING > ND FILTER camera menu, but it’s best assigned to a shortcut button or Quick Menu position so that you can access it quickly while shooting.

Learn photography with Fujifilm, Why You Should Use Neutral Density Filters

Your Next Steps

  • CHALLENGE Grab yourself an ND filter and use a long exposure and tripod to shoot a scene that you’d normally shoot handheld. It could be a daylight street scene or a rural landscape. How does it differ to photos shot without the filter? Post your results to social media with the hashtag #MyFujifilmLegacy. You can also submit your work here for a chance to be featured on our social media channels.