A lot of sky and a lot of water means I went with a polarizer on this picture instead of an ND filter

If you’re a DSLR shooter, there are two indispensable filters you should have in your bag: One is a circular polarizer and the other is an adjustable ND filter or a set of ND filters.

Which of those you choose will likely depend on whether you shoot more stills or more video. As we’ve discussed before when shooting video you’d don’t have the same range of f-stop and shutter speed combinations you do shooting stills. That means on bright, sunny days when normally you’d just bump the shutter speed, you’ll need to use an ND filter or be stuck shooting at f/22 all the time. Video shooters will be more likely to opt for a set of ND filters over an adjustable for consistency.

You pick an f-stop for video for basically the same reasons you select one for photos; to control the depth of field. To get that shallow depth of field filmmakers crave, you may even have stack more than one ND filter.

Polarizers may not be the best choice for video because of issues with consistency. If you have to shoot the same shot from a different angle, common in filmmaking, getting the adjustment right on a circular polarizer is tricky. Add to that the sky color changing on a pan and it becomes clear why ND filters are the preferred choice.

For still photos you’ll have more options because panning is not as big of an issue, unless you’re shooting a panorama. In some situations you can even use a polarizer and ND filter interchangeably.

Polarizers will subtly change the colors, particularly of the sky. ND filters are not supposed to change anything but the amount of light getting through the lens, but not all ND filters are created equal. I have one ND filter that also has a warming tint to it, so be sure and read the specs on what you’re getting.

I generally use a polarizer over an ND filter when shooting either a lot of sky or a lot of water. The polarizer will cut the reflections from water that can blow the highlights. I pick an ND filter in situations where I’m trying to preserve sky colors.

One situation where an ND filter can come in handy is shooting light trails from either cars or airplanes when there’s still enough light in the sky to drive your shutter speeds up.

There are enough situations where I choose one over the other that it’s worth the investment to carry both.

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