Whenever doing macro work with small format I always seem to focus by moving the whole camera and not twisting the lens. After a few hours of this I wish I had a moveble "focussing rack" upon which to mount the camera...if that makes any sense? In the parlance of manufacturing automation, it'd be called a linear stage...I'd mount it to the tripod and then mount the camera to the stage. The stage would allow one to easily move the entire camera in one or two (or, even three!) dimensions.