Archived posting to the Leica Users Group, 1999/10/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]From: Jim Brick <jimbrick@photoaccess.com> Sent: Wednesday, October 13, 1999 23:58 Subject: [Leica] Re: do your homework, please! > People talk about "digital photography", "digital sensors", > etc... but in reality, a "digital" sensor is really an > "analog" sensor. Each pixel position has an associated > capacitor "bucket" to hold the number of electrons that > were allowed to flow in, based upon the number of photons > that the receptor received during the "exposure." Note that both photons and electrons are discrete entities, so you actually end up with a count, not a continuous signal level. The signal is thus digital rather than analog. > The number of electrons held at the pixel site can be > from zero (no exposure) to I suspect billions. The best charge ratios are around 100,000:1, I believe. This is equivalent to about 17 stops in terms of dynamic range. > The net effect is that the more electrons, the higher > the charge, the closer to white. This is clearly an > "analog" event. The charge increments in discrete steps, and there are no intermediate values. Clearly a "digital" event. > So you see, digital cameras aren't really digital at all. No camera can be digital in operation. However, cameras can produce digital images as output. > As I said, the wall is in sight. Time to leave this train > and get on one going in another direction. What do you suggest? -- Anthony