Do you love landscape photography? It provides ample rewards for those who are drawn to the outdoors. Chasing the light can be very exciting but it also poses some significant challenges. What you see versus what the camera sees can be two very different things.
What is High Dynamic Range and why it matters
Much of the best light comes with difficulties related to exposure, and all cameras have limitations when it comes to exposure. The problem is High Dynamic Range or HDR.
Your eyes have an immense dynamic range when it comes to scenes with extremes of bright and dark. Your eye adjusts so quickly you don’t notice it. But your cameras sensor, on the other hand, has a fixed dynamic range. If the scene you’re photographing exceeds that, the camera can’t capture all the details at both ends of the contrast range.
There are several methods for dealing with this limitation:
- You can underexpose the image and allow the darker elements to become silhouettes. But that only works in a few situations.
- You can use a graduated neutral density filter. This works best when there is a straight dividing line between the bright and dark areas of the image. Otherwise, the tops of foreground objects like trees become darker than the bottoms.
- Or you can use a method that works in all situations and the solution is simple. If the sensor can’t capture the full dynamic range in a single shot, take several shots at different exposures that span the dynamic range. Later, in the digital darkroom, blend the images together to make a single image.
There are two parts to the HDR process – capturing the image in the field and processing it in the digital darkroom. Let’s start in the field.
Setting up an HDR shot
Here are the things you need to do to set up an HDR shot for landscape photography. The starting point is your normal landscape configuration.
- It’s customary to use a tripod for landscape photography and this applies to HDR as well. However, with the exciting advances in alignment technology in applications like Photomatix Pro, more and more HDR photography can be done hand-held.
- Set your camera mode to Aperture Priority. You want all your exposures to maintain the same depth of field.
- Set your focus to manual (or use back button focus); you don’t want the focal point changing between shots.
- Use a remote release and set your drive to continuous mode. That way, you don’t inadvertently jiggle the camera when you press the shutter button. This way, one press of the remote‘s button takes all your shots.
- Set your exposure bracketing, you’ll typically want 2 stops difference between shots.
- Set the number of shots, typically 3. But be aware that in extreme conditions you may need 5 or more shots to capture the full dynamic range of the scene.
Note: Your camera may have restrictions on exposure bracketing and/or the number of shots, so you will need to work with that. The important thing is to get enough shots to cover the entire dynamic range.
Now you’re ready to go. For a more detailed introduction, see this article “Setting up Your Digital Camera for HDR Shooting”
How to know you need to do HDR
Your histogram will tell you if you need to use HDR. Here is an example of what you’re looking for.
The histogram spans the range of brightness from maximum dark on the left to maximum bright on the right. For each level of brightness, the graphs shows you how much of your scene has that tone.
The histogram above clearly shows a situation where HDR is needed. The histogram pushes up against the left side, which indicates the shadows are clipping and there is a loss of shadow detail. Similarly, the histogram pushes up against the right side where you have highlight clipping, again, with a loss of detail.
When checking your histogram for potential HDR problems, you only need to look at the left and right sides. What it looks like in the middle doesn’t matter.
Capturing the images in the field
You’ve identified a shot that requires HDR. Next, you’ve set up the shot and taken your set of bracketed exposures.
You got it. Or did you?
How do you know your shots spanned the entire dynamic range? If you’re thinking it’s the histogram, you’re right. You don’t need to check the histogram for every one of your shots, just two – the most underexposed (the darkest one) and the most overexposed (the lightest one).
The histogram on the left is the most underexposed shot. It is well away from the right side. In fact, there’s very little beyond the middle. You may think this is too underexposed, but experience shows that the best practice is to underexpose by too much rather than not enough. There can be areas that are extremely bright but too small to register. It’s better to play it safe.
The histogram on the right is the overexposed shot. Because it is pulled away from the left side, you can be confident you have captured detail in the shadows. Regardless of how many shots you took, these are the only two histograms you need to check.
Making the Best Use of HDR
In landscape photography, you have no control over the light. You need to work with what nature serves up. Sooner or later you will run into HDR situations.
With experience, you begin to anticipate when you need to use HDR. Here are some of those situations, with the before and after images displayed for each. The afterimage, by the way, is the result of the HDR blending and nothing else. More work will be done in Lightroom and Photoshop later.
HDR conditions occur during twilight, the hour before sunrise and just after sunset. During most of this time, the dynamic range is well within your camera’s limits. But there is a period of about 10 minutes or so when the sky becomes very bright while the land is still dark.
This moment captured in Joshua Tree National Park, California, illustrates this issue.
The image on the left is the before image; a single exposure that captures detail in the foreground. Notice how the dramatic sky is lost. With HDR you get it all – foreground, sky, everything. And besides capturing the sky, look at the enhanced detail in the foreground.
Sunrise and Sunset
Often during sunrise and sunset, you want to have the sun in the composition. The bright sun can create an extreme dynamic range, however, and can also confuse your camera’s light meter. The sky may get washed out or the foreground can be darker than you’d like.
Look at this photograph of Thor’s Hammer (above), captured at sunrise in Bryce Canyon National Park, Utah. The hoodoo to the right is an important part of the composition. Getting the starburst of the rising sun through the window adds to the interest.
But the before image without a sky misses another key element. With HDR, however, it all comes together and the moment is recreated.
Full moon at twilight
As it rises through the Venus Belt, a full moon makes an exciting image, with the band of color that sometimes appears in the eastern sky as the sun sets. The best time to capture this is one or two days before the actual full moon.
You may not think of this as an HDR shot. The dynamic range of the earth and the darkening sky is well within your camera’s capabilities. The moon, however, is in full sunlight. It is as bright as midday. So, the challenge is to capture the detail in the moon.