If, like mine, your catalog of images contains quite a few that fell short of capturing the detail you saw with your naked eye, the culprit often is the difference between our eyes’ and our camera’s dynamic range. Our eyes adapt to the changes in a scene’s shadows and highlights, yielding a much larger dynamic range than a camera can. When we look through a scene, our pupils adjust changing their aperture to enable us to see the details in the darkest and lightest parts of the scene. When you capture a single image of the same scene, you only have the aperture you set for that exposure. Any dark areas or light areas outside your camera’s dynamic range will not have detail.
Some years ago HDR, high dynamic range, was introduced to digital photography. Many new cameras and image processing applications touted their ability to automatically produce an HDR image that rivaled the range of the human eye. Like many new techniques, HDR became a fad with a flood of images hitting social media and the internet best described as “crunchy” and unreal. The frequent negative comments about those images stopped many a good photographer from using HDR, even when it could beautifully enhance an otherwise lackluster image. So, when is HDR a good idea? Here is a simple way to tell if your scene will benefit from HDR. Set your exposure and check your camera’s histogram. If the histogram looks like a U with the left and right sides rising high on the graph and the middle staying near the bottom, use HDR. That U shaped histogram is telling you your image is very contrasty with mostly dark shadows and bright highlights that exceed the camera’s single image range. If your histogram doesn’t look like a U, HDR may not give you any more detail than normal post processing can.
The steps to produce an HDR image vary from camera to camera, but almost all newer cameras have an Exposure Bracketing feature. This feature allows you to set your camera to capture 3, 5, or 7 exposures when you press the shutter once and to vary those exposures by a specific number of stops. I typically set my camera to capture 3 exposures with 3/4 to 1 stop between each exposure. The next step is to combine those into a single image in your favorite image processing software. The most popular software (Lightroom, Photoshop, Aurora, Topaz Adjust, etc.) has a built in HDR merge function. You tell it which images you want combined, and the application does the heavy lifting of selecting the appropriate parts of each exposure to yield an image with excellent detail and a dynamic range akin to what our eyes see.
Used judiciously, High Dynamic Range can take the limits out of your photographs.
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