This could be because in Live View the camera's mirror doesn't have to keep going up and down, slowing the process and causing vibrations.
We recommend shooting HDR in Live View mode, since we got sharper images with this mode than in SLR mode using the viewfinder. (A 'stop' is the basic unit of light measurement in photography, representing a doubling or halving of light, depending if you go up '+' or down '-', respectively.) You can also choose between +/- 1, 2 or 3 EV, meaning the 70D will capture the scene at 1,2 or 3 full stops of exposure above and below the middle-of-the-road exposure you would get when taking a single shot. If you select Auto, the camera will determine which exposure compensation steps to use.
Shoot HDR images on the 70D by going into the fourth tab in the Menu, and selecting the level of exposure difference you want between images in HDR Mode.
