Neutral density filters can be one of the most valuable tools in a photographer’s bag. They allow us to bend time to be able to capture more of it in our shots. They’re used for a wide range of photography and filmmaking techniques, but milky-looking water is one of the most popular.
In this code, photographer Jason Row walks us through the process of using a neutral density filter. Jason explains the principles of neutral density filters, how and why we’d use them, and then illustrates the point with some great side-by-side comparisons.
Why do we need a neutral density filter?
The only reason to use a neutral density filter is to reduce the amount of light entering the lens. There are several reasons why people would want them on their lens, though. And they’re used in the worlds of both photography and filmmakers.
Filmmakers who want to shoot in bright conditions with wide lenses use them to do so with reasonable shutter speeds. Photographers may sometimes need to get their shutter speed below the flash sync speed, and neutral density filters on your lens help to do that.
But probably the biggest use for neutral density filters with photographers is for long exposures. “Long exposure” is generally regarded as any photograph where the shutter speed is slower than 1 second. Several seconds to several minutes, however, is most common.
What type of neutral density filter should I buy?
There are two main types of neutral density filters. You’ve got fixed value neutral density filters and you’ve got variable ND filters. The fixed-value ones, as the name suggests, block a set amount of light, and that’s all they’ll ever block.
The amount of light is measured in stops. If you want to cut the light in half, you want a 1-stop ND filter. If you want to cut it to 1/4, then you need a 2-stop. For 1/8, 3-stop, etc. Fixed-value ND filters generally offer the best quality.
Variable neutral density filters are generally more common in the world of video, where you need to react to changing light quickly. But they can be used for photography, too. There are some issues you need to be aware of, though.
The way variable ND filters typically work is by sandwiching two polarising filters together. You’re able to rotate one of these against the other in order to increase or decrease the effect. This sounds great, but they’re not without their problems.
They generally can’t be used with wide-angle lenses. Because they’re basically just two polarising filters, all the caveats of polarisers also apply to variable ND filters. And if you ignore those limitations, the results are impossible to remove from your footage.
But when used with care, variable neutral density filters can work just fine. Especially if they’re low-range ones like the Moment 2-5 and 6-9 stop Variable ND filters ($150-200).
If Jason’s video above isn’t enough to convince you to get a neutral density filter, be sure to check out Ole’s guide to using neutral density filters to photograph landscapes. And if you’re still not sure, here’s a complete beginner’s guide to using ND filters.
