Thanks, everyone... That's is kind of what I was thinking. I set out a deer rack a Cabela's 400 yards away in the shade of a tree, i put a brown shirt over the bleached skull. What you gain in maginifaction you loss in shake. I compared them side by side. The 8.5's slightly smaller image, way eaisr to hold steady.
I will be mounting the Vortex on a tripod!