There are times when you’ll have correct exposure in only parts of your image. Others will be lighter than you want them to be.
This is where we use neutral density filters, or the graduated version, to bring out detail in those areas.
Read on for all the information you need on how and when to use them.
What Is a Neutral Density Filter
An ND or Neutral Density filter stops light from entering the lens and hitting the sensor. These fit on the front of the lens with the help of an adapter.
Or you can buy these neutral density filters that clip on the inside of your camera body. The adapter that holds your ND filters needs a ring to fit onto your lens.
Most manufacturers provide these rings, ranging from 49 mm to 82 mm. The neutral density filter looks like a square of dark glass.
You can buy graduated ND filters, but these are for sunsets, and bring down the light from only part of the scene.
Many companies sell packages. You can buy adapters and rings, and a whole range of ND filters and graduated filters together. Your parents might even have some Cokins lying around.
The ones I use are from Rangers. They provide 4 ND filters and 4 Graduated Filters (2, 4, 8, 16), 9 Filter Adaptor Rings (49-82mm), ABS adapter. And they all come in a nice pouch.
ND filters are quantified by their optical density. Or a little simpler, their f/stop reduction. An ND16 filter will lower your f/stop by 4 stops. Instead, you can lower your shutter speed, which is more beneficial for long exposures.
What Is a Graduated Neutral Density Filter
A graduated neutral density filter is a neutral density filter with a gradient. These start at their darkest on one of the lengths.
And then they will get lighter until the middle of the glass (this process is gradual, hence the name).
The rest of the glass has no density filter, only the middle to top. They are designed to make one area of your image darker. But keep the rest of your scene untouched.
These will affect the sky, blocking out some of the light leaving your landscape as you see it.
The gradual change helps to keep a nice transition between the dark and light areas. You won’t have a strong, noticeable line.
They are finicky to use, especially compared to the neutral density filter. You need to find that sweet spot. If the filter is placed too low, the graduated ND filter will affect your landscape.
Too high, and you won’t cut out enough of the sky. This will create a noticeable gap between where the sky meets the landscape.
The holder of the graduated neutral density filter helps you move the glass to the perfect angle. As you can turn it, it offers you a 360° angle of movement.
This is for cases where the landscapes’ horizon isn’t exactly 180° or flat.
The graduated neutral density filters I will be using are the LEE Soft Graduated Filter set. These give me three filters; a 0.3, 0.6 and a 0.9.
These will take out one, two and three stops of light.
We are using the LEE filters as they are made from glass, so the filter’s colour won’t affect the image. This was a problem I found with the Rangers kit, which you can read about here.
Why Would You Use One
You may find that during a very light day, parts of your image will be exposed. But others will turn out overexposed. This is particularly common when photographing land and the sky.
A neutral density filter keeps the scene very natural. Unlike HDR images, it allows you to edit with limited post-processing knowledge. For more information on how to create HDR images, read our article here.
Both areas deal with the natural light from the sun in different ways. The land soaks it up and sends it our way, as reflected light. The sky acts like a lightbox, becoming many stops lighter than the other areas.
You can see this when you try to photograph buildings and sky together. Or when photographing an interior, the light through the windows becomes too strong.
Our intention with the Graduated Neutral Density filter is to eliminate some of the light from the sky. This will make it a closer exposure to the land.
Another way to do this is to photograph a High Dynamic Range (HDR) image.
This is where many exposures of different exposure values darken and lighten different areas of the image. And when stitched together, they balance the highlights and the shadows with the mid tones.
This is a great option for creating very high-resolution images. But they take longer and you need to know how to post-process them.
Firstly, I wanted to find a location with rolling hills and a beautiful landscape. I was in Venelle in Aix-en-Provence, in the south of France, recently and that’s the area I had to work with.
The trees in the foreground stopped the perfect landscape image, but that was the best I could find in the local area.
On the front sat the filter holder, and the filter pouch sat wrapped around my belt.
Setting up the camera and tripod was easy, as I wanted to be as high as possible. The horizon, I wanted to get as close to 1/3 sky as much as possible to follow the rule of thirds composition rule.
This is my base image, with the exposure meter placed on the landscape in the middle of the image. I metered here as this is the area I wanted to have a perfect exposure from.
Metering the sky would have darkened the landscape, making the filter pointless.
As you can see, the sky is a little burnt out, with little detail. As I said, the sky had been stormy, so there was some definition, and the sky was darker as a result.
You will no doubt come across brighter skies and darker landscapes.
To start with the filters, I took out the weakest of the three. I slid this into the holder, with the darkest part at the top.
The holder will need to have the ‘stoppers’ on the sides, as the filter is too big for them to help.
This is the image with the 0.3 filter, which pulls out one stop of light.
This image is using the 0.6 filter, which pulls out two stops of light. As you can see, the skies in the images are becoming darker.
The final image was made using the 0.9 filter, which pulls out a total of three stops of light.
Here, you can see the effect of the 0.9 graduated neutral density filter, compared to the base image with no ND filter.
The same concept as the above, only moving the location to see how it would affect the light in the sky.
Here is the base image with no filter. The only difference in the location is that my exposure went from 1/13 to 1/15.
This is a tiny difference and could have come down to a stronger patch of metered light.
This image is the 0.6 filter, pulling two stops of light out of the sky.
This image is the 0.9 filter, pulling three stops of light out of the sky.
This below image is an experiment I wanted to try. This was to show you the effects of not having a graduated ND filter that isn’t flush with the horizon.
I turned the filter 45° clockwise, meaning only the top right-hand corner of the sky and landscape had the neutral density filter over it.
You can see the difference as those areas become darker.
This would be a handy way to create a specific mood in your images.
Problems With Graduated Neutral Density Filters
Just like everything else in the photographic world, there are downsides to using ND filters.
You will experience these problems when you find yourself pushed for time, or really need to get that shot. We call it Murphy’s Law.
Problems will also arise in images where the light needs the most amount of control, right down to the horizon.
But there are other areas that break the horizon. Perhaps it is a mountain or some other geographical area.
The ND filter will affect these areas when you pull the light from the sky. And it will fit neither the sky’s exposure nor the landscape’s.
“How can you solve this?”, I hear you ask. You can’t really, but there are two things you can try.
First, you can fix the problem during the post-editing stage. As long as you photographed the scene in raw, it should be relatively easy to add or subtract exposure values in areas of your image.
Lastly, you can blend images together. Stitching together two images and using the brush or eraser tool in Photoshop will reveal parts of the second image underneath.
For me, the problem was trying to find that sweet spot, where I captured all of the skies without darkening the landscape. This takes a little time to get used to, but a quick tip I found. While the graduation of the filter ends in the middle, I needed to have it only in the top 1/3 of the image.
If I sat the ND filter in the holder, making the bottom of the glass flush with the bottom of the holder, that was the best place to make sure the ND filter affects only the top 1/3.
Using a neutral density filter is a simple enough way to capture a great landscape scene without too much fuss. You also don’t need a huge amount of post-editing know how.
Grab some filters, head out and try it. It will definitely help.
A note from Josh, ExpertPhotography's Photographer-In-Chief:
Thank you for reading...
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