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. :D 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