I wish the auto focus / target for 3D orbit in both AutoCAD & DWF viewer would make atleast some effort to compensate for panning and zooming.
Orbit around whatever happens to be in the centre of the screen. Re-aquire orbit targets automatically doesn't have to be perfect. Other 3D packages don't seem to have too much problem with this although eventually they can get confused but atleast they seem to be making some effort to track the users movement and retain a sensible rotation centre.