This is a tough one that I've always been unsure about. How do you determine a focus tolerance when a projector is at an angle or projecting on to a curve? Usually I just focus to the middle point and that does the trick (if you're far enough away), but how does one simulate or calculate that?   I've seen this called projector "depth of focus" and "depth of field" - though depth of focus makes more sense to me.    Here's a good example –    I'm projecting on a curve