Modern cameras are highly complex and intelligent devices. But how many times have you returned home from a shoot where you could see detail across the entire scene, only to find that the camera was unable to capture exactly what you saw? The problem is that digital cameras are simply unable to capture the dynamic range of the human eye. You might feel disheartened when your images don’t represent what you saw but you shouldn’t, because no matter how experienced you are, no photographer can capture detail in every part of a scene in a single image.
ND grad filters can help to maintain sky detail, but if there’s a high amount of contrast then shadows will always come out too dark. Don’t despair though – the limitations of cameras are part of what makes photography so much fun! Finding ways to manipulate the way light is recorded and represented can prove to be one of the most challenging things we face, and that’s one area where HDR comes into its own.
Get perfect exposures
HDR images are most commonly created using three shots of exactly the same scene taken at different exposures – one to correctly expose for the midtones (which is usually the foreground), then two further images that are 2 stops overexposed and underexposed from the exposure of the first shot. You can also shoot five, seven and nine shots for a smoother graduation between each exposure. There is a small improvement in image quality as a result of shooting more frames, but three-shot HDR images are more than adequate for 95% of photographers. Not to mention they’re easier to shoot and take up less space on your hard drive.
If you would like to try shooting more than three exposures you’ll have to shoot in manual mode. Take the first midtone image and then change the shutter speed 1 stop at a time and take another shot. It’s the gap of 1 stop rather than 2, and the additional exposures, that improves overall image quality in the final result. However, shooting more than nine images won’t make any difference to image quality at all, so there really is no point expanding further.
For our HDR tutorial we'll concentrate on shooting three exposures in aperture-priority mode using autoexposure bracketing. This method requires you to set the initial exposure only, and then the camera will take three bracketed shots with a single release of the shutter button. It keeps the shooting stage of HDR photography nice and simple, plus it helps to reduce the risk of camera movement between shots.
1. Compose the shot
Frame your scene handheld before attaching the camera securely to a tripod in the desired position. Make sure that the tripod is stable and the head is fixed in place to eliminate the risk of movement between exposures. Focus either manually or using autofocus. If you do use AF, set the lens to manual focus to lock focus at the desired point after focusing. Focus must remain on the same point for every shot you take for seamless blending.
2. Find exposure
Set your camera to aperture-priority mode at f/11 with ISO set to 100. f/11 is the sweet spot of most lenses, and will provide the best overall image quality in terms of sharpness. Take a test shot and assess the exposure of the midtones on the LCD screen. These are usually found in the foreground area. Finally, apply exposure compensation to lighten or darken the exposure of this ‘middle’ shot if necessary.
3. Set bracketing
Once you have your middle exposure, it’s time to set autoexposure bracketing (AEB). This is usually found in the camera’s menu, and since all cameras are different you may need to check your camera’s instruction manual. Once the setting has been located, set the bracketing amount to 2 stops. Now release the shutter with a cable release or use the camera’s self-timer. The camera will shoot three bracketed exposures.
This article was first published in the August 2015 issue of Practical Photography - download back issues here.