A sunset can be so bright that the sky turns white while the land below is nearly black. A graduated ND filter fixes this by darkening only the sky. In a different situation, perhaps filming while walking from shade into sun, you might want a filter you can make lighter or darker by simply turning a ring. That is a variable ND filter. Both are versions of the ND filter from the previous lesson, but they work in quite different ways and have their own strengths and limits.
What is a graduated ND filter?
A graduated neutral-density filter (often called a grad or GND) is a filter that is dark on one part and clear on the other, with a transition between them. You place the dark part over the bright sky and the clear part over the darker land, so the sky is darkened while the land is not.
This solves the problem you met in highlights, shadows, clipping and dynamic range: when the sky is several stops brighter than the land, the camera cannot keep detail in both. A grad brings the two closer together in a single exposure.
Hard, soft and reverse grads
| Type | Transition | Best for |
|---|---|---|
| Soft edge | A gradual change from dark to clear | Uneven horizons: mountains, trees, buildings |
| Hard edge | A quick, sharper change | Flat, straight horizons such as the sea or open plains |
| Reverse | Darkest right at the horizon, getting lighter toward the top | Sunrises and sunsets, when the brightest band is at the horizon |
Grads usually come in 1, 2, 3 or 4 stop strengths for the dark part. A 2-stop grad darkens the sky by two stops while leaving the land unchanged. The choice depends on how much brighter the sky is than the land, which you can measure by spot metering each, as you learned in camera metering.
Remember:The transition looks sharper or softer depending on focal length and aperture, too. A soft grad can look almost invisible on a long lens, while a hard grad can look gentler on a very wide lens. Testing shows you how your own filters behave.
Using a graduated ND filter
- Use a square filter system so you can slide the filter up and down; see filter systems.
- Compose on a tripod and decide where the horizon falls.
- Measure the difference between the sky and the land, and choose the grad strength.
- Slide the filter down until the transition sits on the horizon; in live view, the effect is easy to see.
- Watch for objects that cross the horizon, such as trees or buildings: they will be darkened too.
- Check the histogram for clipped highlights and dark shadows.
Grads or bracketing?
Today, many photographers balance skies by taking several exposures and combining them, as you learned in HDR and exposure bracketing, or by darkening the sky in editing. Grads still have advantages: everything is captured in one frame, so moving clouds, water and leaves are not a problem, and the RAW file starts closer to the final result. Bracketing handles complex horizons better, such as a tree that rises into the sky.
What is a variable ND filter?
A variable ND filter (VND) is a screw-in filter whose darkness you can change by rotating it, for example from 2 to 8 stops. Inside are two polarizing layers. Turning one against the other blocks more or less light.
This makes a variable ND very convenient, especially for video. Video usually needs a shutter speed linked to the frame rate, often about double it, such as 1/50 at 25 frames per second, for natural-looking motion. A VND lets filmmakers keep that shutter speed and their chosen aperture while the light changes, just by turning the filter.
Limits of variable ND filters
- The "X" pattern: near the strongest setting, many VNDs show a dark cross or uneven blotches across the frame, especially with wide lenses. This is called cross-polarization. Avoid the very end of the range; many good filters have hard stops to prevent it.
- Uneven skies: because VNDs work with polarization, they can darken parts of the sky unevenly, like a polarizer does, as you saw in polarizing filters.
- Image quality: two layers of glass and polarizing film mean cheap VNDs can lose sharpness or add color casts.
- Limited strength: most are not suitable for very long exposures; a fixed 10-stop filter is better for those.
| Fixed ND | Variable ND | |
|---|---|---|
| Adjustment | One strength per filter | Adjustable by rotating |
| Evenness | Even across the frame | Can show an X pattern at high strength |
| Best for | Long-exposure photography, highest quality | Video and quick changes in light |
Common mistakes
- A grad line cutting through mountains or buildings: they look unnaturally dark at the top; choose a softer grad or use bracketing.
- Using a hard grad on an uneven horizon: the line becomes obvious.
- Turning a VND to its maximum: the X pattern appears.
- Using a VND on top of a polarizer: the polarizing layers interact and give unpredictable results.
How professionals use them
Landscape photographers using grads often carry soft and hard grads in two or three strengths in a square system, and combine them with a polarizer. Many also bracket when the horizon is complex. Filmmakers rely on high-quality variable NDs, or switch to fixed ND filters, sometimes in matte boxes, when image quality matters most. Both groups know the limits of each tool and choose based on the scene.
Practical examples
A seascape at sunset
- Situation
- The bright band of sunset at the horizon is clipping while the rocks in front are dark.
- What to do
- You use a 3-stop reverse grad with its darkest part on the horizon.
- Why it works
- The brightest light sits right at the horizon; a reverse grad darkens it most.
- Result
- The sunset keeps its color and the rocks show detail in one exposure.
Filming a walking interview
- Situation
- You walk with a speaker from shade into bright sunlight while filming.
- What to do
- You use a variable ND and turn it darker as you enter the sun, keeping your shutter speed and aperture fixed.
- Why it works
- Video needs a consistent shutter speed; the VND adjusts for brightness instead.
- Result
- Smooth, consistent footage without changing camera settings.
Key points
- A graduated ND darkens part of the frame, usually the sky, while leaving the rest clear.
- Soft grads suit uneven horizons; hard grads suit straight horizons; reverse grads suit sunsets.
- Grads capture balance in one frame; bracketing handles complex horizons better.
- A variable ND uses two polarizing layers to give adjustable darkness, ideal for video.
- Avoid a VND's maximum setting to prevent the X pattern; use fixed NDs for long exposures.
Frequently asked questions
What is a graduated ND filter used for?
Should I buy a soft or hard grad?
What is a variable ND filter?
Why do I see an X across my photo with a variable ND?
Conclusion
Graduated ND filters balance bright skies with darker land in a single exposure, and variable ND filters give instant control over darkness, especially for video. Choose the grad type to match your horizon, avoid a VND's extreme setting, and use fixed NDs when quality and long exposures matter most. Next, you will finish the filter section with diffusion and creative filters.
Finished reading? Track your progress through Lenses and filters.