Shortly after that guy first invented the camera, some other guy (or girl) noticed that their exposure was not always perfect. So, they came up with the idea of bracketing photos, which is nothing more than taking your photo, and then underexposing one and overexposing another one. Then, just in case the first try wasn't perfect, one of the other images would probably be closer to what the photographer was looking for.
Of course, for years that was all done manually, one at a time. However, with most modern digital cameras, that ability is built right in. My camera, for instance, can take up to 9 bracketed images, with up to 1 f-stop between each one - it first takes the metered correct exposure and then starts underexposing and works right up to the last image which will be 4 f-stops overexposed. You just have to check your camera's manual to see how to set it up to do this.
As often happens, none of the images - even the bracketed ones are correctly exposed. Like those 3 above, the sky is too bright, or the trees and foreground too dark. So, what do we do?
Our eyes can see about a 20 f-stop range, while digital cameras typically only record a range of about 6 to 8 f-stops. Beyond that, the image may have very dark (or black) shadows and highlights so bright they've turned pure white with no visible detail. This usually results in disappointing images that don't look anything like the scene we saw when we took the photo.
The
main reason I bracket these days is not to get the best exposure but to get a range of exposures to use with software like
Photomatix Pro to get what is called a "high dynamic range" (HDR) image, one that more closely resembles what our eyes see in the shadows and highlights.
If you'd like to see what's possible with this technique, go take a look at
HDRspotting.com. There are many truly amazing images there that will most likely get you really excited about HDR.
Then, once you've decided to take the plunge, go to Trey Ratcliff's wonderful travel photography blog,
"Stuck in Customs", look at his images, and then check out his
HDR Tutorial.
(Trey had the first HDR photo to hang in the Smithsonian.)
