ABSTRACT
The lateral magnification of a thick centered optical system in air, using the Lagrange theorem in Eq. (1.60) and the definition of lateral magnification for a distant object, is given by
m ¼ u1 u0k ¼ y1 l1 u
ð3:1Þ
assuming that the object and image media are the same (typically air). The effective focal length of a thick lens or system of lenses is defined
by
F 0 ¼ y1 u0k
ð3:2Þ
hence, the lateral magnification with a distant object depends only on the effective focal length F, independently of the particular lens configuration. With this definition we may see from Fig. 3.1 that the effective focal length is the distance from the focal plane to an imaginary plane called the principal plane.
