Optical design codes whose optimization routines rely heavily on aberration coefficients proved ineffective in finding "global" optima in the non-rotationally symmetric world of "compact" eccentric pupil telescopes. Manual "steering" of the optimization process resulted in "rediscovery" of the Schwarzschild Principle.
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Eugene W. Cross, "Eccentric-pupil reflecting-telescope development," Proc. SPIE 10263, Lens Design: A Critical Review, 102630D (1 July 1992);