> Roger, > > Insightful as usual!! The truth is that I don't know the details of my > question. It is just that it struck me that electronic devices somewhere > along > their "response" chain behaved like or somewhat like film at the "toe" and > "shoulder" of a film characteristic curve. And maybe even in the > midportions > possibly. Is "reciprocity" or the "reciprocity law" (actually I don't > think it > is a "law") followed by digital devices since we've been shown it is not > by > "analog" ones like film? Hmmm. The digital sensors are, at bottom, photon counters, right? (Not capturing 100%, but capturing a fixed percentage of the photons that hit them?) To the extent that's true, their response would inherently be "linear" in number of photons. Human vision *isn't* linear, though, so the sensors will deliver results differing from the human perception. It's certainly possible to clip the highs (easily demonstrated :-(), so the sensors aren't perfectly and totally linear under all conditions.
