> Winsor Crosby <wincros@xxxxxxxxxxx> wrote:
>
>
> The way I understand it is that the AF system generates a double
> image for the active focus point, just like a rangefinder, at least
> with the phase systems like the D200. It is set up so there is never
> a zero even at perfect focus. The distances between the double images
> are mapped in the controlling chip to distance. So in this case the
> camera always knows whether it is in focus or out. If the images of
> the fence post are x microns apart the lens is focused at distance y.
> It is more like the early rangefinders that read a distance that you
> set on the camera by turning the focusing ring except that here the
> controlling chip, not you, is doing it.
>
Then the camera must need to do some sort of image recognition. I wonder how
it works focussing on a regular grid ?
...Wayne
Wayne Harridge
http://lrh.structuregraphs.com
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