Hi, I'm shooting interior retail space and will be using a Canon 17-40 L USM on a Canon 5D Mark II. I wanted to ask a few basic questions. I'm using a 580 EXII speedlite as a slave bouncing off ceiling/wall: I usually shoot 640 ISO for interiors - should I be shooting slower speed? I'm currently shooting ETTL (not manual) at f8/f11 - dont want more depth of field than that. Am shooting the interior space by placing camera on a tripod at navel height (I'm 5'10" tall). Is it worth trying other angles - such as climbing on a stool for a top down view or ground level shots? Thanks.