AEB is a process often used by photographers with a plan to merge the three photographs using some type of HDR software. This is something that can be very helpful in your day to day photography as well. There are times when you will find the lighting for a shot to be particularly difficult. That is where AEB can save you time and in many cases save your photograph as well. You can manually shoot the same photograph with several exposure levels and then pick from those three the best for you needs. That can be time-consuming and may cause you to loose that perfect shot such as a sunrise or sunset.
With the AEB (Automatic Exposure Bracketing) that is built into many DSLR cameras, you can set the camera to shoot a series of 3 or 5 pictures. Each is on a different exposure level. When you have that very bright day and you know that many parts of the photograph may be overexposed you can set a series of photographs at -.3, -.6 and -1.0 exposures. This will give you three RAW images at different exposures to get the one best for your editing needs. The system can be used in reverse as well by shooting night pictures with higher exposures.
We use a Nikon D7000 and Nikon in their wisdom has limited their cameras in that series to only the 3 exposures. Still, it is a tool that is easy to use, after setup when you shoot a photograph you simply hold the shutter button until you hear the camera shoot all three of your images within a couple of seconds.
Look at the example photographs below. We had our camera set to be 0, +2 and -2 to use in an HDR panorama but the principle is the same. You have the three photographs and you choose the best for you. You will have three photographs composed identically but with slightly different exposures.
If your camera does not allow you to complete the three shots without pressing the shutter button three times then you can set to Burst Mode to get the same three shots.
Each camera has a different setup for AEB when it is available but most of the time it is in their menu section. Once setup in the menu section some cameras like our d7000 have a button near the lens that allows us to turn it off and on as we need to use it.
Get out your users manual to see how AEB works on your model. Ours gives us .3 then .7 then 1 stop. This is usually as far as we go unless we are planning to use the images as an HDR when we will increase to +2 and -2 along with our 0 exposure variance. I would start with the .3 and .6 then go from there as you need. You can still easily make these changes in the field if you see you need to go higher or lower based on conditions.
For even more control in Automatic Exposure Bracketing mode, you can use either Aperture Priority Mode or Shutter Priority Mode. When you choose to use AEB in Aperture Mode it allows the camera to adjust the shutter speed to the Aperture you have chosen and in when used in Shutter Mode it the camera will adjust the Aperture to the conditions while maintaining the shutter speed you have selected.
I hope you will find this helpful, please comment below if you have any questions.