I know three methods for determining the optical center of a figure (on the vertical axis):
1) given by Harold Evans (after V. Steer) in Newspaper Design (1973);
2) proposed by Albert A. Sutton in Design and Makeup of the Newspaper (1948);
3) "just trust your eye".
Each of them gives, let's say, quite different results. Common to these methods is that the optical center lies slightly above the geometric center of the figure (I don't mention my students claim the optical center is located right in the middle).
The question is:
do you know other methods, formulas or have links to similar issues which would help to clarify or form an opinion on the matter?