Archived posting to the Leica Users Group, 2000/11/04
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> > Since you, the human, who are looking at the ground glass screen, know what it > > is that you want in focus, how can a computer program written by a programmer, > > sitting in a cubicle somewhere, know what you want to focus on > Autofocus is a tool and, like any > other tool, it can be used effectively or not effectively. I'm surprised > that you, Jim, with your experience of digital photography would voice such > a nonsense argument. > Autofocus knows when *something* is in focus: it is up to the photographer > to choose *what* to focus upon. The autofocus doesn't try to guess *what* > you want to focus on any more than it tries to guess what you had for lunch > last Thursday. Jim is absolutely right, and it is not nonsense. The autofocus systems are one, not guideable, two, have an angle of view, and three typically require some contrast. If one could guide the autofocus to a specific point in space, that would be a different story...but the current systems don't work that way. There is no way you can tell it to focus halfway down the face so only the left eye of your subject is in focus. If the subject's face is in the autofocus domain, it will focus 'somewhere' on the face. The technology that would work is to have retina tracking that knows what spot you are looking at, with a very small angle of view, and focus there. No one has that availability yet, and the sensors, and computing power necessary for that, in such a small package, are possibly tens of years away.