Just last weekend I attended a two-day course on pinhole photography run by
David Gepp, who spent a year or so making pinhole pictures of Venice. He
showed the pictures on the course, and they were all 20 x 16in enlargements
from 5 x 4in Fujicolour 160NPD negatives - an enlargement of 4 times. But
one, a view of St Mark's Square from a balcony atop the Basilica, was a
huge 36 x 30in enlargement from 5 x 4 - an enlargement of more than 7
times. To be sure, you couldn't examine them for sharpness with a loupe,
but from normal viewing distance they looked wonderful.
The weekend, BTW, was highly inspirational.