A graduated neutral density filter, commonly shortened to graduated ND, GND, or ND grad, is dark across one half and clear across the other, with a transition zone in between. It is used to hold back the brightness of one part of the frame, almost always a bright sky, while leaving the darker foreground unaffected. By darkening only the top, it squeezes a high-contrast scene into a range the sensor can record in a single frame.
The need arises because the sky is often several stops brighter than the land beneath it, more than the camera’s dynamic range can hold at once. Without help, you either keep sky detail and lose the foreground to shadow, or expose for the land and end up with blown highlights in the sky. A graduated ND rebalances the two so both record properly, which makes it a staple of landscape photography.
Graduated filters come in several transition styles. A hard-edge grad shifts abruptly from dark to clear and suits flat horizons such as a sea view. A soft-edge grad blends gradually and works better when hills, trees, or buildings break the skyline. A reverse grad is darkest at the center and lighter toward the top, designed for sunrises and sunsets where the brightest band sits right at the horizon, and a blender offers an extra-gentle transition.
They are rated in stops, marked either as stops or in optical density, where 0.3 equals one stop, 0.6 equals two, and 0.9 equals three. To choose the right strength, meter the bright sky and the foreground separately, note the difference, and pick the grad that closes most of that gap. A two-stop or three-stop soft grad covers most conditions.
These filters are usually large rectangular sheets held in a bracket so you can slide them up and down and position the transition exactly on the horizon, unlike a screw-on round neutral density filter that darkens the whole frame evenly. The main limitation is that the dark half also darkens anything that rises above the horizon, so mountains, trees, and buildings poking into the sky can come out unnaturally dim. Like other filters, the better ones are color neutral so they darken without adding a cast.
A graduated ND is the in-camera alternative to digital approaches such as exposure blending and HDR, and many photographers combine glass and software, using a grad to get close in the field and finishing in post. For practical technique on the land, see our guide to how to use graduated neutral density filters.
A practical field routine is to compose, meter the foreground for the look you want, then slide the grad down until the sky reading falls into balance, checking the histogram for clipped highlights. Soft-edge two-stop and three-stop grads handle the majority of sunrises and sunsets, which is why most photographers reach for those two first.