An empty is nothing more than a point in space and it doesn't render in the final image. Tap the spacebar and select empty from the add menu. It will be displayed as a small xyz axis. Deselect everything, rightclick the camera then shift+rightclick the empty. With both selected hit CTRL+T and select constrained. Now when you move the empty the camera will track it. Simple. :o) As far as the OSA I don't think it can be set to render any finer than 16. I'm not sure about that one.