This tutorial describes how to enter fields and wavelengths. Can specify wavelength and weighting and be sure to select the primary wavelength for all other calculations. There are four methods to enter and describe your field of view. Object space angle, object space height, Image Height (paraxial and real).1.Refine construction of a first order microscope in Zemax

Utilize paraxial lenses
Infinity corrected with 200 mm tube lens
9.0 mm Diagonal sensor (1/2” CCD)
NA of 0.2
20x
What is the size of the object field? Verify with Zemax.

Reference: Optical design of microscopes by G. Seward