Michael Rigby-Jones wrote:

>   I wonder what the typical eyeball resolution is?

Dredged from my imperfect memory, diffraction limiting is about 4.56
arcseconds per inch of diameter.  The aperture of the pupil is about 5mm
(7mm for a young person in low light levels), so for perfect eyes,
resolution would be about 23 arcseconds at 5mm aperture and 16.5
arcseconds at 7mm aperture.  When I was young and Venus was up in the
evening sky and at its brightest, I could not detect the crescent disc
with the bare eye, but could easily do so with a pair of 7x50
binoculars.  I'd guess the practical limit for the average eye lies
somewhere near the bottom of that range (about 30-40 arcseconds to an
arcminute)

>  I would think the brain probably performs some kind of resolution
> enhancement.

Edge enhancement and motion detection among others.

Jim