Definition
Long exposure is a technique that keeps the shutter open for a long time, from about half a second to several minutes, so anything moving is recorded as a blur while still parts of the scene stay sharp. It turns water into mist, streaks clouds and car lights, and needs a tripod.
Daylight at f/11 and ISO 100 meters at 1/60s. A 10-stop ND filter multiplies that by 1,024, giving about 17 seconds, long enough to smooth a choppy sea. For a fast stream, half a second is often enough; for slow sea swell, plan for 30 seconds or more and time it with a timer.
Calculate it for your own shot with the Long Exposure Timer.
Also used in: ND Filter Calculator, Phone Camera Mode Finder
Long exposure records time as a single blended image instead of an instant, and it produces effects that cannot be faked convincingly from a normal frame. Moving water turns to mist, clouds streak into motion lines, a crowd of people can vanish because nothing stayed in one spot long enough to register, and car lights draw ribbons down a night street. The length has to match the subject's speed.
A fast mountain stream smooths out in half a second, while slow sea swell needs thirty seconds or more to lose its texture. Push too far and you lose the thing that made it interesting: a two-minute exposure of dramatic storm clouds can blur them into a featureless grey wash. Every long exposure also needs the camera locked down, because any shake during those seconds smears the static parts of the frame along with the moving ones.
A photographer at a rocky coastline shoots the same wave-washed boulder four ways from a tripod. At 1/250s the spray is frozen into separate droplets and the water looks violent. At 1/2 second the moving water softens but still shows direction and flow around the rock. At 5 seconds the surface turns to a smooth blur with just a few bright streaks where waves broke.
At 30 seconds, held open with a 10-stop ND filter, the sea becomes a flat, fog-like layer and the boulder seems to float. The photographer keeps the 5-second frame, because it holds a sense of the water moving while still clearing away the clutter of individual splashes that made the fast version look chaotic rather than deliberate. A cable release and mirror lockup keep the boulder itself crisp while the water alone carries the blur.
Guides for this tool, by niche
Related terms
Troubleshooting