I'm fairly sure that quote is only to give a sense of how big "20°" is, as most people aren't intuitively familiar with vision cones. I can't find anything tha

I'm fairly sure that quote is only to give a sense of how big "20°" is, as most people aren't intuitively familiar with vision cones. I can't find anything that actually states the focal distance, though I agree there's a decent chance it's at infinity.