I've used my mask a couple of times now visually for public presentations where I want to be close to '20/20' focus. A couple of points on this- if you wear glasses, the focus point with and without your glasses will change. This may seem obvious, but I tested this just to be sure.

Also, I noticed that some of my eyepieces will change the focus point depending on the position of your eye in relation to the eyepiece. I found if you move around in the eyepiece, the center diffraction spike will move as well! Maybe that's not true for the really good eyepieces, but my moderately priced eyepieces had this tendency.

Maybe I need to buy an Ethos now just to test this theory... anyone want to back me up with my wife?