Saturday, August 15, 2009

Bracketing

The classical solution to improve your chances of getting the exposure correct has been bracketing: Take multiple shots with different settings to get different exposures of the same scene. Typically you take one shot exposed normally followed by one or more overexposed and one or more underexposed shots. Check your camera manual and it is very likely that your camera offers an auto-bracket option for exposure where you can set the number (usually three or five), order and step interval (1, 1/2 or 1/3 stops). My Pentax K20D has a special exposure bracket button on the outside of the camera to quickly switch between bracketing and non-bracketing, no doubt the other brands have similar functionality to avoid going through long setup menus.

Bracketing has always enjoyed a questionable reputation as it wastes a lot of film when used with film cameras and because of the randomness of the approach. True, without taking steps to correct the lightmeter, you are in fact taking several potshots to see if you can obtain a good result. However, when you take the prize of a correct exposure of a difficult shot, nobody will poke fun of you but applaud you for being careful.
On a Digital SLR, the waste of images is of course less of an issue, especially when you take the quickly dropping prices of memory into account (and you're not on a long trip with just the one memory card.) 

Let it be clear that you don't need bracketing unless you are confronted with a difficult subject. Still, no matter how easy bracketing sounds, you still need to make decisions about the number of exposure and the step intervals. You'll need to learn to judge the subject to make those decisions, but usually three exposures with steps of 1/2 a stop is a save bet. We'll be getting back about how to judge subjects.