Filters
ND Filter Guide: Which Type Do You Actually Need
The short answer
An ND filter controls exposure and shutter speed for video. Here's how the main types compare, and which guide to read for your camera or lens setup.
What's covered5
An ND (neutral density) filter reduces the light entering your lens without changing color, which lets you keep a slower shutter speed for natural-looking motion blur in bright conditions, or open up your aperture for a shallower depth of field without overexposing the shot. Filmmakers need one almost anywhere they're shooting outdoors or under bright lights, since a camera's shutter speed for video is usually locked to a specific frame-rate-driven range that has nothing to do with the actual light level.
Fixed vs. variable ND filters
A fixed ND filter reduces light by one set amount and needs to be swapped for a different filter (or stacked with another) as light changes. A variable ND filter rotates through a range of light reduction in a single filter, trading a small amount of optical quality for the convenience of adjusting on the fly as you move between shots or the sun moves across the sky. Most working filmmakers now default to variable, covered in more depth in our variable neutral density guide.
By camera and lens setup
If you're shooting on a fast cinema lens, check our cinema lens and Canon cinema lens f1.4 guides for why wide-open apertures make an ND filter close to mandatory outdoors. Shooting on a phone instead of a dedicated camera has its own filter format, covered in iPhone ND filter. For uneven lighting across a frame, like a bright sky over a darker foreground, a graduated ND filter targets just part of the image instead of the whole frame.
Not sure which ND filter fits your camera and lens combination? The Filmmaking Gear Starter Checklist covers filters alongside the rest of a starter kit.
Specific filters worth knowing
Some ND filters are worth knowing by name because they're widely used or heavily marketed. See our guides on the NiSi True Color ND-VARIO Pro Nano and the Peter McKinnon ND filter line from PolarPro for how those specific products compare to the wider market. For a full roundup across brands and budgets, see best ND filter, and for a straightforward answer to "which ND filter should I actually buy," see welchen ND filter.
For lighting gear that pairs with ND filter use outdoors, see a softbox-based lighting setup (covered in an upcoming guide).
What actually determines the right pick
Three things narrow the decision fast: your lens's filter thread size (or the camera system's filter mount, if it's built into the body), how wide a range of light conditions you shoot in during a normal week, and whether speed of use or maximum image quality matters more to you. A documentary shooter moving between locations all day usually wants a variable filter for speed. A narrative cinematographer lighting each shot carefully has more reason to use fixed filters, since optical quality matters more when every frame is being scrutinized on a bigger screen.
A mistake worth avoiding across every ND filter type
Buying a filter sized for one lens and assuming it fits every lens in your kit is a common and avoidable mistake. Filter thread sizes vary by lens, and a step-up or step-down ring is a cheap fix, but only if you know you need one before the shoot day, not after unpacking gear on location.