ND Filters for Video, Explained: Stops, Variable vs Fixed, and When You Actually Need One

If your outdoor footage looks slightly harsh, jittery on movement, or your subject is blown out no matter what you do, you are probably missing one cheap piece of glass: a neutral density filter. ND filters are sunglasses for your lens. They cut light without changing color so you can keep the settings that make video look like video. Here is what they actually fix and how to choose one.

The problem ND filters solve

For natural motion, video wants a shutter speed near double your frame rate — 1/50s at 24–25fps, 1/60s at 30fps (the "180-degree shutter rule"). Outdoors in daylight that setting lets in far too much light, so your image blows out. Your instinct is to raise the shutter or close the aperture, but a fast shutter makes motion look stuttery and video-ish, and a tiny aperture throws everything into focus and kills your cinematic background blur. ND filters remove the extra light instead, so you can keep the right shutter and the aperture you want.