That is a good point about the angle of view business. The numbers I posted were from using Pinhole Designer, but I'm sure it is based on the "perfect pinhole," an infinitesimally thick sheet of absolutely opaque non-reflective material with a perfectly round hole (since it's infinitesimally thick, it's got a knife edge for sure. As anyone who has tried it well knows, the ideal is only a goal and some of us don't get anywhere close to it. And at the minimum, the light fall-off is an issue of the hole becoming a narrower and narrower ellipse viewed from an angle off the pinhole to film axis, eventually a (closed) line at 90º. But that too can be complicated by the actual fabrication.One popular magic constant is 1.9
Anyway, the calculations I suggested above were to illustrate my approach to the original poster's question. You have to pick some basic parameter(s) and work out the rest. When I did my pinhole body cap for the SQ-A, the film format and film to pinhole spacing were pretty much fixed, so there was no point in agonizing over angle of view calculations, other than to learn what it was.