What is HDR Photography
What is HDR Photography?
HDR stands for ‘high dynamic range.’ Dynamic range is simply the difference between the lightest and darkest areas of a photograph. Once a scene exceeds a camera’s dynamic range the bright areas will blow out to white and the dark areas become black. HDR is a technique that gives us a higher dynamic range of light that a camera can’t achieve in a single image.
For example, if we are taking a photograph of St. Michael’s Church steeple at sunrise and expose to the bright steeple the storefronts and street below will be too dark. If we expose to the storefronts in the foreground the steeple will be totally over-exposed and we’ll lose all detail in it. What to do?
Benefits of HDR Photography
Basically, HDR allows us to take 3 [or more] photos at different exposure levels and blend them together into one balanced image with a full range of tones & details. Some cameras (and smart phones) have this as a built-in feature. If not, you will have to purchase a post-processing software program and then add and adjust your bracketed images manually. My camera does have a HDR setting, but I do not like its flat, washed-out tones, so I take bracketed images that I can adjust manually on my computer in post-processing.
When photographing outdoors we have changing latitudes in the natural light [thank you, Jimmy Buffett]. If we have soft and diffused light, like an overcast day or in the shade, the contrast between shadows and highlights will be reduced, and therefore the dynamic range of light is also reduced. At these times we do not need to use HDR.
But, on a sunny day the light is hard and very directional, giving us dark shadows while subjects in the sunlight are very bright. This strongly contrasted scene has a huge amount of dynamic range, one that our camera’s sensor cannot handle. This is where HDR photography is very useful.
Another example would be indoors with bright windows and a dark interior. If you expose to the windows the room goes solid black, but if you expose to the room the windows and areas around them are over-exposed. On a recent trip to Rome I used HDR constantly in dark churches with bright windows to get well-balanced images that otherwise would have been impossible to take.
Problems with HDR Photography
One problem with HDR photography is that is has acquired a bad reputation. The internet was flooded with surreal, fake-looking, oversaturated and gritty HDR images. HDR images have decreased contrast in an effort to balance out the various exposure and can appear ‘washed out.’ So, we have to add contrast to them and sometimes this gets out of hand. They also can add more color saturation than normal photographs and need to have the saturation reduced to look normal. So between these two problems we can easily get images that have a grungy, painterly look that loses a sense of realism. HDR is a technique, not a style. Be careful not to over-do it and end up with images that look cartoonish.
When taking your HDR images you should set your camera to aperture priority to maintain the same depth of field for similarly focused images. If you have the camera set on automatic it will decide on the aperture and can change it from picture to picture and it doing so it can change your depth of field and focus. [Or you can hold down the ‘lock focus’ button if you have it.] A tripod is also recommended so all the bracketed images are aligned the same.
In another life I seldom used HDR in Colorado and Utah while taking outdoor photos. But in Charleston, or any urban setting, with mixed light and dark areas in a scene, this is a very useful tool to have.