A lot of people have never heard of HDR (High Dynamic Range) photography, but those who have are often divided as to whether it's "true" photography, or just a cheap post-processing trick. While it's most definitely the wrong way to go about getting a natural-looking photograph, when done well, this new technique can bring an amazing degree of luminosity and contrast to landscapes and portraits, as well as being an interesting way to overcome problematic lighting - particularly sunsets.
In simple terms, HDR photographs are a composite of three or more shots of the same subject, each taken at different exposures. These are then combined to produce a much wider tonal range than a single photograph usually contains, using software like Adobe Photoshop CS2 or HDRsoft Photomatix Pro. As you can see from Figure 1, the results can be pretty striking.
You'll find the trial of Photomatix Pro and three of the shots I used to create this panorama of Sydney Harbour Bridge on the Cover Disc of the October 2006 issue of PC World Magazine, so you can try it out for yourself. There will also be instructions for Photoshop CS2 owners. Please note that these images are for non-commercial purposes only and credit must be given if you use them for anything else.
Where to begin
You'll need a camera that offers a full manual mode (i.e. lets you set both aperture and shutter speed) and a tripod. Because you'll be shooting numerous exposures of the same scene, you can't really take shots of subjects that are moving, unless you want them to look blurred and shifted in the final product - which is why HDR photography is generally reserved for landscapes or static portraits. Look for subjects with a wide range of lighting; HDR is particularly useful at overcoming poorly-lit interiors with bright windows (like cathedrals and stained glass), or cloudscapes where you want to expose the land as well as the sky (which would normally involve the use of a graduated neutral density filter).
Frame and focus your shot with the camera on the tripod and set it to the aperture you want for the scene's depth of field (deeper is better for HDR landscapes), then pick the shutter speed that gives you the "normal" exposure that you'd usually aim for. Use manual focus, and use either a remote control or the timer to activate the shutter without moving the camera.
Drop the shutter speed down a couple of notches for the next image, and then set it two notches higher than the original for the final shot. You can add more shots to the process by repeating the process, taking the exposure two stops further each time. If your camera supports it, you can use exposure bracketing of +/- 2 stops to automatically take three shots at differing exposures. Just bear in mind that you'll typically get better results with more exposures, which requires the use of the full manual method.
Note: While you can change the exposure settings using aperture settings instead of shutter speed, this may affect the depth of field, causing blurry results. If you intend to use exposure bracketing, be aware that some cameras adjust the aperture for this feature.