The Viewing Angle option allows you to view the molecule with perspective. The viewing angle is the angle subtended by the left and right edges of the viewing window, as seen by an observer on the positive Z axis. A value of 25 is normal human perspective, and a value of 60 is like looking at the molecule with a telephoto lens. A value of 0 gives no perspective.
Note: A value entered here other than zero (0) will have strange effects with the on-screen editing capabilities of Molecular Editor.