A 1x1 inch chunk of the original 4x5 negative scanned at 1200 pixels
per inch and downsampled to 600 x 600 pixels for this detail sample.
As a single parameter, the smaller the pinhole, the better the
resolution/focus (although the higher the equivalent f stop). As
with so many things in life, there is a second effect, Rayleigh
diffraction caused by light bending around an edge. This effect
takes over with very small holes and is the final limiting factor.