O boy. Pinhole photography is, by nature, low-res; it's an aesthetic of d.i.y. and has no need for precise focus. That noted, pinholes have approximately the same depth at any given distance from 9"-infinity if they are properly fabricated, and so, the circle of confusion is standardized throughout that range. As I said earlier before my stalker added his convoluted two cents. And I repeat, if you make the hole too small you begin to get interference from the edge--regardless of what you choose to call that distortion.