Many digital cameras include an Auto Exposure Bracketing (AEB) option. When AEB is selected, the camera automatically takes three or more shots with a different exposure for each frame.
Auto Exposure Bracketing is a very useful option for taking HDR scenes. However, AEB was not really intended for HDR shots initially, but rather for ensuring that at least one of the shots will be as close to perfectly exposed as possible. This is probably why some camera models only make it possible to auto bracket three shots at a maximum of one EV step difference or even less.
Unfortunately, three shots spaced by one EV are often not sufficient for properly taking HDR scenes. This is why it is important to look at the settings of the Auto Exposure Bracketing features of a camera model to determine whether such camera will be convenient for HDR shooting. The number of frames per second that the camera can take (referred to as “burst rate” in the table below) is another important factor for HDR shooting — the fastest the auto-bracketed shots, the less pronounced ghosting and mis-registration problems will be.
The table below lists the AEB settings of various camera models. The table lists settings provided by the camera manufacturer, firmware upgrade included, but does not take into account possible firmware upgrade enhancements via third-parties tools such as CHDK.