What are Graduated ND Filters and when to use them

Using square ND Grad Filters

Graduated ND Filters have long been the trusty companion of a Landscape Photographer, being with them side-by-side during the golden hour with the sole purpose of catching that perfectly balanced shot between sky and foreground.

Just ask Landscape Photographer/writer Marie Gardiner:

“ND grads are a must have in my kit bag, I never go anywhere without them. On the occasions I’ve been too lazy to use one, I’ve always regretted it later. Not only do they stop you blowing your highlights but they also just generally help to bring more definition to the sky, which makes for a more interesting photograph.”

When to use Graduated ND Filters

Any landscape photographer will tell you that the time an ND Grad filter earns it’s money is during the ‘golden hour’; a sunrise or sunset. But it’s not all sunshine and rainbows, as the golden hour poses the greatest challenge of light management between sky and foreground. If you were to expose the sky in your scene, the foreground would be very dark. If you were to expose the foreground, you would have an overexposed image (below).

Graduated ND Filters: Overexposed Image
Image courtesy of Lee Filters

When setting up your scene, you will see the difference in stops between the sky and the foreground. The general rule of thumb is to have both the foreground and sky within one stop-of-light. Any larger, then you’ll want to use Graduated ND Filters to achieve a well-balanced exposure (below).

Graduated ND Filters: Good balanced exposure image
Image courtesy of Lee Filters

Marie Gardiner added, “when you have a scene that’s really high in contrast, then ND grads are worth their weight in gold. Bright white/grey skies can mean that without a filter, you’re sacrificing a good exposure by crunching your shadows or blowing out your highlights to compensate. Using an ND grad (and I prefer a soft grad) brings down the exposure of the sky (or water, or snow, and so on) to give you a much more balanced image.”

How does an Neutral Density Grad filter work?

When using an ND Grad, perfectly balanced exposure is achieved by the darker part of the filter holding back more light than the clearer part of the filter. The less over-exposed light to reach the camera lens, the more balanced the sky and foreground become.

For example, lets say the sky is three-stops lighter than the foreground in our scene. We want to get that difference down to one-stop to achieve balanced exposure. For this we will use a 0.6 (two-stop) ND Grad filter and position it on the horizon so that it covers the sky. This two-stop filter will hold back two-stops of light while keeping the foreground as it is. Resulting in a perfectly balanced exposure.

TIP: It’s called neutral because the darker part of the filter should not make any colour changes to your scene or producer any colour cast. Only choose the best filters for the best shots!

SEE MORE Our 5-star neutral density filter set

Types of Graduated ND Filters

An ND Grad filter has many different types to help achieve the perfect result. These types vary in the darkness and strength of the filter, and a difference in the transition line.

What is a Hard ND Grad filter: An ND Hard Grad filter has a sudden definitive line of transition between the clear and dark gradient part of the filter. This is great for shooting a definitive horizon like a seascape or flat landscape.

SEE MORE ND Hard Grad Filter Set

What is a Soft ND Grad filter: An ND Soft Grad filter has a more gentle blend from dark to clear making the transition line seem less obvious. This is the filter to use when there is no clear horizon, like a forrest or city-scape.

SEE MORE ND Soft Grad Filter Set

What are the different strengths to an ND Grad filter: Either lighter or darker, each strength is to compensate for different lighting conditions. Darker filters hold back more light than lighter strengths. For example, a 0.6 (two-stop) ND Grad will hold back more light than a 0.3 (one-stop) ND Grad. A 0.9 (three-stop) ND Grad will hold back less light than a 1.2 (four-stop) ND Grad. As the F-stop reduction table shows below.

BONUS: If you have a very bright sky, ND Grad filters can also be stacked to hold back more light.

Graduated ND Filters
ND Hard Grad (left) and ND Soft Grad (right)
Graduated ND Filters: ND F Stop reduction
F Stop reduction table

How to use a Graduated ND filter

Now you know capabilities of Graduated ND Filters, its time to set up your shot:

  1. You’ve found your scene, so extend your tripod, attach your camera and take a light-meter reading of both the foreground and sky.
  2. Work out the difference in exposure between the foreground and the sky, and use an ND Grad filter to get them within one-stop of each other. (Remember, if the sky is three-stops lighter than the foreground, use a 0.6 ND Grad filter to reduced the exposure difference to one-stop).
  3. Slide the ND Grad filter into your holder and position correctly for your horizon.
  4. Expose the scene for your foreground and *CLICK*, take the shot.

SEE MORE Choosing a Holder for Square Filters

A bit more: Reverse Grads

This is the part where landscape photographers will sit up and take note, as Reverse ND filters are designed purposely for that golden hour shot. In honour of the latest release from Lee Filters, the Lee Filters Reverse ND Grad Filters, it’s important to understand the abilities of a reverse ND Grad filter and what it can achieve.

The sole purpose of these filters is to reduce horizon exposure to achieve perfectly balanced sunrise and sunset shots. And this is done by the difference in placement of the transition line, in comparison to a normal Graduated ND Filters. The transition line of a Reverse ND Grad filter is, like many, in the middle of the filter. But, instead of going from clearer to darker, it starts dark and then fades to clear towards the top of the filter. Making them ideal for scenes when the sun sits close to the horizon.

Here’s a video by Mark Bauer to tell you more:

SEE MORE Shop Lee Filters

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