Reverse ND filters: what are they, and when should photographers use them?

Lee reverse ND grad filter

What is a reverse ND grad?

A reverse ND grad darkens skies, just like a normal ND grad, but instead of getting darker towards the top of the filter, it has the darkest part close to the transition in the middle of the filter, and then a lighter area towards the top. 

Sunsets are the most common reason for using a reverse ND filter, as this with (above right) and without (above left) comparison shows (Image credit: Chris Rutter)

What does reverse ND grad filter do?

A reverse ND grad darkens skies, just like a normal ND grad, but instead of getting darker towards the top of the filter, it has the darkest part close to the transition in the middle of the filter, and then a lighter area towards the top. 

When should I use a reverse ND filter?

When shooting scenes where the brightest area of the sky is close to the horizon, such as sunrise or sunset, with the sun in the frame. 

The low sun was shining straight through these swaying grasses, but it was much too bright for any detail in the rest of the scene to show up (above left). The reverse ND grad filter (above right) produces a much better picture. You can see the grasses more clearly, but the blue sky above the sun isn’t over-darkened. (Image credit: Future)

How is a reverse ND grad used?

Using a reverse ND grad is similar to using a normal ND grad. You need to pay particular attention to the positioning of the filter to avoid darkening the land or sea just below the horizon. 

The effect of graduated filters is obvious in the finished picture but not always easy to see in the viewfinder, so you may prefer to switch to Live View as you position the grads. Take time over this, because it’s hard to cover up mistakes later. 

Using Live View is one of the best ways of lining up a grad, or a reverse grad, in the filter holder (Image credit: Future)

Anything else I need to know?

Because the darkest area of the grad is close to the center of the filter, it’s almost impossible to avoid darkening any subjects that are above the horizon line when using a reverse ND grad. 

Two ND grad filters put back to back makes a makeshift reverse ND filter (Image credit: Future)

Do I really need to buy another filter?

Some filter makers produce bespoke reverse ND filters which have a darkened strip in the center only. But there is a way to achieve a clever effect without having to buy an extra filter.

All you need is two graduated ND filters. Instead of using them to double the filter effect, you turn one of them upside down so that it overlaps the first to produce the darker ‘stripe’. As long as you use the weaker filter upside down, the sky will still be darkened relative to the foreground.

Try turning one of the filters upside down. As you move it across the other filter, you’ll see a darker strip appear where the graduated sections overlap. If you’re careful you can align this darker strip with the sun just above the horizon.

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