I’ve been getting questions about some of the landscape photos shown on this website, so I thought it might be useful to outline how I've been generating “high dynamic range” (HDR) images. A conventional snapshot requires that you select a single exposure for the scene, and that works quite well for many photographic situations. But landscapes, which typically include features that are very bright (like sky) and very dark (like shadows), can lose a lot of information in that snapshot, at least compared to what you see with your eyes. That’s because your eyes and your brain combine to allow you to perceive a much wider range of light and color and detail than what a camera can capture in a single photo.
HDR photography relies on a computational process to combine multiple exposures into a single image, and the result is a vibrant and detailed picture that is closer to what you see with your eyes. Some cameras and smartphones have a setting that enables some form of automatic HDR processing. This often results in a somewhat improved photo, but if you really want to see what HDR processing can do, there’s no substitute for dedicated software.
Before I get into the details, let me show you how HDR processing can help with landscape photography. Below is a snapshot of the Maroon Bells near Aspen, Colorado, using my camera’s auto-exposure setting. With brightly lit mountains in the background and shadowed trees in the foreground, this scene illustrates the classic auto-exposure dilemma: the camera does its best to choose the exposure automatically, but the picture loses a lot of detail because the lighter features are over-exposed and the foreground is under-exposed.
The photo below is identical except that I chose a faster shutter speed, so less light is getting into the camera. Now you can see more gradations and detail in the snow and the clouds, but everything in the shadows is lost.
This next photo was taken with a slower shutter speed, revealing all the details of the trees and rocks and water that are in the shadows. Now, of course, the bright background is washed out.
HDR processing combines all the rich detail and color that were in various portions of the original three photos, resulting in the picture below. After the software does its magic, I typically do nothing more to the final HDR image other than adjust the black level slightly to improve overall color saturation, and this image is the best representation of what my eyes saw that day as I looked toward the Maroon Bells.
In order to incorporate HDR processing into your photography workflow, you’ll need two things: First, you have to use a camera that has the capability of rapid photo capture by holding down the shutter button (“continuous shooting”) as well as the ability to change the exposure in those photos automatically (“automatic bracketing”). There are many digital SLR cameras that do this; I am currently using a Nikon D750. Second, you need a good HDR software application. I use Photomatix Pro 5 software on a MacBook Pro, and this software is also available for Windows computers.
To capture images for HDR processing, set the camera to continuous shooting with autobracketing at 2 EV. Each EV (also called a “stop”) corresponds to a change by a factor of two; for example, +2 EV means that the picture will be over-exposed by four-fold. With the camera set this way, holding the shutter button down for three rapid shots will capture images that are normally exposed, over-exposed, and under-exposed.
Landscapes are well-suited for HDR photography since there is usually little or no movement in the picture, allowing easy alignment of the multiple exposures. The HDR software automatically corrects for any slight tilting of the camera between the rapid-fire shots, so you don’t need to use a tripod. However, if there’s some wind blowing the trees or birds flying, “ghosts” will appear in the final HDR images and ruin them.
Once you have collected your triplicate images, you just need to load all of them into Photomatix Pro and then start batch processing. HDR processing is a powerful tool, but there is a fine line between its use and abuse in nature photography. You can usually see poor implementation in the form of halos around darker features, or unnaturally over-saturated colors. If your goal is like mine -- to better capture what you see rather than produce surreal or stylized images -- then the "Details Enhancer" settings in Photomatix Pro can be adjusted to avoid these artifacts.
I’ll end this little tutorial with a side-by-side comparison of the original single exposure (below left) and the corresponding HDR image (below right). The differences are not always this dramatic, but rarely is the HDR version a disappointment.