QC 351 A7 no. 57 / A normalization of the Delano y,ÿ diagram is proposed in which the y heights are normalized by the entrance pupil height, the heights by the image height. The normalization constants are expressed in terms of the system parameters, and it is seen that the reduced distances become normalized by the focal length of the system, the marginal ray reduced angles by the numerical aperture of the system, the chief ray angles by the field aperture, and the powers by the total power of the system. It is also shown that any number of refractions and transfers will not affect this normalization, but a stop or conjugate shift will destroy it and renormalization then becomes necessary.