Exposure Bracketing: What Every Good Photographer Should Know
Article from Light Stalking
There arent many sure things in life. No matter how diligently we plan, regardless of how much effort we put forth, there are simply going to be times when the outcome of whatever we are involved with is going to be the exact opposite of what we wanted. It stinks, I know; it can be frustrating. But thats just the way life goes sometimes, what are you going to do? When it comes to photography, however, theres actually a practical answer to that. Yes, theres a way to ensure that you get a good exposure every time. Its called exposure bracketing.
Three Times a Charm
Exposure bracketing is a technique that produces a series of (typically) 3 images, one of which is captured at the proper exposure setting as determined by the camera, while the other images are captured at a fixed interval both above and below that of the original exposure. Essentially, you will have one underexposed shot, one overexposed shot, and one perfectly exposed shot. If it has not become obvious by now, you will find bracketing most useful in tricky lighting situations that tend to give your cameras metering systems fits. Landscape shots, for instance, where the foreground and the sky require different exposure settings; or shots where your main subject is accompanied by an overabundance of light; or winter scenes so uniformly dressed in snow. Of course, you can only choose one exposure level for any given shot, so thats why you might determine that it would be a great idea to take multiple shots at varying exposures.
Let the Camera Handle it
Bracketing does pose one apparent problem, however: in order to make 3 different exposures of the same subject, youre going to have to move your camera to change settings, thus foiling your pursuit of an identical shot. Sure, you could grab your tripod and employ it as a personal assistant of sorts, but there are plenty of times when a tripod is just going to be more of a hassle than a help. If youre shooting film, this may be your only viable option. But for those of you with a dSLR, the solution is built into your camera.
Typically referred to as automatic exposure bracketing (AEB), all you will need to do is dial in the desired intervals (the number of stops above and below the baseline exposure) and let the camera take over from there. Some cameras will take all 3 exposures with just one press of the the shutter button, while others will require you the press the shutter button for each shot. *FYI: Most dSLRs also allow you to auto bracket white balance, flash exposure, focus, and other parameters
So, AEB has given you 3 different exposures of the same thing — now what? Well, its possible that one of the non-standard exposures actually suits your needs or creative preferences better than the standard one; go with whatever you like. Thats what freedom of choice is all about. Or you may want to blend your bracketed photos into a high dynamic range (HDR) image. For more on HDR processing, see Jason Rows tutorial.
Another option available for your trio of photographs — and an increasingly popular alternative to HDR processing — is exposure fusion. Exposure fusion software assess a series of images for contrast, luminosity, and saturation, then assigns a weight to each pixel of every image in the series based on this criteria. The weight of a pixel is then used to determine whether that pixel is retained in or discarded from the final image. In more simple terms, exposure fusion takes only the properly exposed bits of each image in a series to produce a final photo that represents the original scene exceptionally well. While exposure fusion is a more basic post-processing technique than HDR, it avoids the drastic visual transitions often associated with HDR images.
There was a time when cameras didnt have built-in exposure meters. Crazy, right? Back then, photographers were forced to sometimes guess at their exposure settings. I can only assume that with enough practice, some photographers became rather proficient at being able to recognize by the lighting conditions around them precisely how much to adjust their shutter speed in relation to what film they were using. I can even see how some would argue that this helped photographers of the pre-digital age develop a more intimate understanding of light which, thus, made them better photographers. In the end, what matters most is getting exactly the shot you want, the means less so. If you havent picked up your cameras manual in a while — or ever, now might be a good time to do that; locate the bracketing mode in your camera and give it a spin. It just might open up some creative possibilities that had not occurred to you previously.