I've been a boom op, sound designer, recording engineer, as well as general tech guy and even producer on several student films, medium budget productions, and corporate/gov't video projects.

On many occasions, I've had to explain to very experienced cinematographers as well as directors and even educators teaching video production how exactly focal length, perspective, and foreshortening works.

Of course, good luck getting any of those folks to sit down and watch an educational video that seems to be explaining "basic" concepts!

I remember one time a director insisting on a certain shot, and once he described what he wanted I had to explain why it wasn't going to happen without blowing a hole through the ceiling to get the camera much further away from the subjects on a straight-down shot. Certainly was no budget for that .