lovelifey: [Photography] Graduated Neutral Density Filters: The Ultimate Guide

The post Graduated Neutral Density Filters: The Ultimate Guide appeared first on Digital Photography School. It was authored by Barry J Brady.

a guide to graduated neutral density filters

What is a graduated neutral density filter? And how can you use one to capture beautiful landscape, cityscape, and architectural images?

In this article, I explain everything you need to know about graduated ND filters, including:

When GNDs are helpful (and when they’re best avoided)
How to use a graduated neutral density filter for great results
Whether it’s better to use GNDs or Photoshop to handle high dynamic range scenes
Much more!

Ready to master the art of the GND filter? Let’s do this!

What is a graduated neutral density filter?

A graduated neutral density filter, also known as a graduated ND or an ND filter, is a rectangular piece of glass or resin that is partially – but not completely! – tinted. It features a gradient that moves from dark to light:

Graduated ND filters generally use a special holder to mount in front of the lens; they then block light from part of the frame while leaving the rest of the frame untouched.

Why is this useful? Certain scenes, such as coastal landscapes at sunset, feature bright skies and dark foregrounds. Due to sensor limitations, your camera often can’t capture the entire tonal range in a single frame – so if you do try to shoot a bright sky and a dark foreground, you’ll end up with a pure white sky and/or a pure black foreground.

But by placing a graduated neutral density filter over the lens, you can block light from the brightest part of the scene (i.e., the sky). This reduces the tonal range of the scene and allows your camera to capture the entire shot in a single frame. You’ll get a well-exposed sky, a well-exposed foreground, and an all-around great image! Make sense?

When should you use a graduated neutral density filter?

Graduated ND filters are most commonly used by landscape photographers, but they’re helpful in pretty much any situation that involves a clear horizontal (or vertical) division between light and dark. Cityscape photographers, for instance, use GNDs to capture beautiful skyline shots, while architectural photographers use GNDs to shoot houses and other structures when the sky/foreground contrast is too intense.

Of course, setting up a GND filter takes time, so I’d recommend you forego the filter whenever possible. In other words, don’t overdo it; if your scene doesn’t feature a large tonal range, it’s probably better to just shoot normally and leave the GND in your bag.

My recommendation? Use graduated neutral density filters when shooting foreground-sky scenes at sunrise or sunset (i.e., during the golden hour). Before sunrise or after sunset, however, you can safely shoot without a GND.

I used a graduated neutral density filter to photograph this scene, which featured strong contrast between the sky and the foreground:

As you can see, the graduated ND filter reduced the brightness in the sky just enough to render cloud detail, and I was able to get plenty of detail in the foreground, too.

By the way, you can also use graduated neutral density filters during the day to allow for longer exposures – so you can create interesting blur effects in your images – but I’d really recommend you use standard neutral density filters for that, not GNDs. They’re slightly easier to work with, and they’ll generally get you better results in the daytime, anyway.

Types of graduated neutral density filters

Graduated ND filters come with a few different variables, and if you want to get the best results, you must pay careful attention to your options.

First, GND filters feature either hard edges or soft edges:

As you can see in the image above, a soft-edge ND filter offers a more gradual transition between the clear and the dark section of the filter. A hard-edge ND filter, on the other hand, features a rapid transition between the two sections.

A hard-edge filter is useful if you have a very definite horizon line (e.g., a seascape where the horizon is simply water). You can let the dark portion cover the sky and position the gradient edge over the horizon line.

A soft-edge filter is designed for scenes without a straight horizon line, such as a sunset over a forest or a sunrise over a city. The gradual tint lets you darken the sky without an obvious transition line, so you can position the edge roughly over the horizon and get a good result.

Second, graduated ND filters feature different strengths. Darker filters hold back more light, and these are necessary for photographing scenes with huge tonal differences between the sky and the foreground – whereas lighter filters hold back less light and are perfect for photographing scenes with smaller tonal differences.

Note that different GND filters are referred to using stops of light (where the number of stops refers to the difference between the dark and light portions of a filter). Here are the common graduated ND filter strengths:

1 stop (0.3)
1.5 stop (0.45)
2 stop (0.6)
2.5 stop (0.75)
3 stop (0.9)

Therefore, when choosing a GND filter for a scene, you must carefully evaluate the difference between the foreground and the sky. The standard advice is to reduce the sky so it’s within one stop of the foreground – so if you decide that the sky is three stops brighter than the foreground, you could use a two-stop GND filter. And if you decide that the sky is four stops brighter than the foreground, you could use a three-stop GND filter.

What if the sky is more than four stops brighter than the foreground? In that case, you can stack multiple filters to make the sky even darker!

How to use a graduated ND filter: A step-by-step method

Working with a GND filter is easier than you might think. There are a few technical details to consider, but once you’ve used grads a few times, it’ll get super easy – trust me.

Here’s a process that works well in most lighting conditions:

First, set up your camera on a tripod and take a meter reading off the foreground. (To do this, make sure your camera is in Manual mode, then point it down and fill the viewfinder with the foreground. Note the position of the exposure bar in the viewfinder.)

Next, take a meter reading off the sky using the same method. (Again, note the position of the exposure bar in the viewfinder.)

Compare the two meter readings. Calculate the difference between the first and second exposure bars using stops. For example, if the foreground meter reading is -2 and the sky meter reading is +1, there is a 3-stop difference between the two.

Pick a graduated ND filter that brings the sky and foreground within a stop of one another. If the difference between the sky and the foreground is 3 stops, you can use a filter that blocks two stops of light (that is, a 2-stop or a 0.6 GND). And make sure that you choose the right type of GND filter. Remember, if you have a hard horizon line, use a hard-edge grad; otherwise, stick to a soft-edge grad.

Slide the ND grad filter into place in front of the lens and carefully position the gradient over the horizon line.

Finally, expose for your foreground and take your shot!

At this point, if you’ve done everything right, you should end up with a good image. However, I recommend you always check the results on your camera’s LCD screen. (If your camera offers a histogram, pull it up and check for clipping.)

If you do notice issues, that’s okay. Just make your adjustments and shoot again!

As I said at the beginning of this section, it takes some practice to become a smooth user of GNDs – but the results are worth it!

Editing your graduated neutral density images

Once you’ve captured a well-exposed scene, you’ll have a good file – but to make it look its best, you should take it into your favorite post-processing program and add a few finishing touches.

Now, there are many different ways to enhance an image and make it pop; I am not going to go into all the different adjustments. However, I do have a few pieces of advice:

First, I recommend you work on the sky and foreground separately – either by creating masks in Photoshop or by using graduated filters in a program such as Lightroom.

Once you’ve separated out the sky and the foreground, you can darken down the sky to make it more foreboding, you can adjust the colors, and you can experiment with other adjustments (such as a contrast boost).

Then you can lighten up the foreground to show detail, do some dodging and burning to add depth, and add a subtle vignette.

Of course, you’re free to ignore my advice; processing is very subjective, and at the end of the day, it’s your preferences that matter!

Graduated ND filters vs Photoshop

All throughout this article, I’ve discussed the value of GND filters, but you do have another option:

Photoshop, Lightroom, or any other post-processing program that offers exposure blending.

You see, instead of using a GND filter, you can get a similar effect by shooting several images at different exposures (e.g., one image exposed for the sky, one image exposed for the foreground), then blending them together while editing.

Which method is best? It’s often just personal preference. GNDs offer a couple of pros – for instance, you can see the results immediately on your camera’s LCD, and you don’t have to spend extra time processing your photos.

On the other hand, good GND filters are expensive, plus exposure blending can be a bit more versatile. You don’t need to worry about encountering jagged horizon lines, you don’t need to worry about stacking GND filters if the sky is really bright, and you don’t need to worry about picking the perfect GND filter.

So decide which method appeals to you most, and get shooting!

rocky shoreline long exposure sunset graduated neutral density filter

Graduated neutral density filters: final words

Hopefully, you now feel ready to capture some stunning images using GND filters!

As long as you spend plenty of time practicing, you’ll get very good, very fast. Using GND filters will soon become second nature, and you’ll feel like an absolute pro.

Now over to you:

What do you plan to shoot using graduated ND filters? And what filters do you plan to use? Share your thoughts in the comments below!