25-50 millimeters, maybe.
An understanding of simple mathematics with a bit of trigonometry
thrown in should be more than enough to cause someone to reject
the notion that something such as a license plate could be retrieved
from an image consisting of barely a quarter-million pixels. (DVD
resolution, which would be much higher than that which would be
found on "home gear") Most standard-def gear I've dealt with is
lucky to read a plate on a moving vehicle 50-feet away looking
straight at it.