This brings to mind the debate about solar time vs atomic time. Humans more or less live by the former, but most our machines utilize the latter. Thus, we have to periodically do things like reset the clocks of the GPS system to keep it tuned to the wobbly day/night cycle of Earth, rather than the "more accurate" oscillation frequencies of atoms.
#1 makes a good point. A silver halide photograph is composed of tiny, uniform-sized crystals, each of which is either all white or all black. In other words, on the structural level, a chemical photo is every bit as discontinuous and illusory as a digital photo.