In a previous blog on Histograms, I included photos where I had used Auto Exposure Bracketing (AEB). So why and when would you use AEB? I see a couple of times when it really makes sense: 1) when you are not sure what is the best exposure set-up under changing light conditions, 2) when you have high contrast lighting such as in night photography.
When AEB is used, the camera will automatically adjust either aperture, speed and/or ISO while keeping the other two constant depending on the camera shooting mode you are using. I believe that setting the ISO and aperture and having the camera bracket the exposures by changing the speed provides the best results under most circumstances. In fact, when using AEB I use aperture priority for most of my photographs. Using aperture mode allows me to have better control of what is in focus and the depth of field of my photos. Actually, aperture priority is my go to mode for 95% of my photos. Your camera’s user manual will go into the specifics as to how to set your specific model for AEB.
1) Several years ago on a trip to Amsterdam, my wife and I took a boat trip through several of the canals. As we traveled along the canals, we were moving from shadows, to cloudy and sunny conditions. I set the camera up to do AEB with three exposures: normal, plus one f-stop and neg one f-stop.
Photos above are unprocessed Raw Files
Also the camera was set to use continuous focus (CF) and multi-exposure mode, so when I depressed the shutter button all three photos were taken one after another. Why didn’t I just take a single photo and correct the exposure when I downloaded it to my computer? When you make adjustments to your photo on the computer, there is always the potential of increasing the noise in the original photo. So, it’s important to get the best exposure possible when taking the photograph. I could have accomplished the same correction when I shot the original photo by using the exposure compensationfeature, but when you’re standing on a moving boat it’s impossible to make the exposure compensation correction and still capture the picture. The continuous focus (CF) and multi-exposure mode, is just as I recommended in my blog on Photographing Children , where I wanted to stop the motion of a constantly moving child. Here I wanted to compensate for the moving boat.
2) I’ve used AEB in night photography because it often presents a high contrast situation, i.e. bright lights and dark shadows. In situations like this it’s important to use a wider range of F stops: normal, plus 2 F stops, and neg 2 F stops. This technique is referred to as High Dynamic Range (HDR).
Always use a tripod as the exposures can be long. It’s imperative that you also use a cable release, or remote triggering of the camera. Any contact with the camera will cause the images to be blurred. In the example below the exposure times ranges from 0.6 to 10 seconds.
Using the three photos above, I combined them using Photoshop’s HDR Merge, and then cropped, sharpened and increased the clarity.
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