Quote Originally Posted by RalphLambrecht View Post
Your math is correct, and doing it mathematically is just fine, but some people prefer a graph such as the one attached.
You're right, Ralph.
I use tables, a somewhat less graphic way, but still a form of a 'look-up' solution.

Your graph also assumes symmetrical lenses.
Which is the only way to present such data, as long as we don't know in advance what sort of lens will be used, and how it's exit pupil position differs from it's focal length.