> I'm glad to hear that there's apparently nothing not understood now. I
> didn't say anything at the time but when you first posted this "problem"
> I wondered why I could never recall seeing anything similar with either
> my Minolta A1 or Samsung WB650 which both, of course, have CDAF. And,
> in terms of digital technology years, the Minolta is already ancient
> history.
The Minolta A1 really isn't that far off from "current
state-of-the-art". The processing engine behind the focusing function
is a bit slow in comparison to today's overclocked wonderbricks, and
the motors themselves are not quite the swiftest things around. But
the algorithm and methodology which the A1 uses is quite advanced and
probably more superior than the typical bear.
The focus sensing is classic CDAF. However, the camera generally will
work a bit of a focusing sweep to determine closest subject when in
multi-point (or area) focusing mode. The algorithm determines where
the closest "subject" (or place in the frame that comes into focus at
the nearest setting) and will then base the subject exposure on that.
This is also how the Nikon 3D Matrix metering system works with
D-series AF lenses. The Canon and Olympus AF systems work similarly,
but with variations to the algorithm and underlying technologies used
to accomplish the task.
What has happened is that the bulk of this technology is actually
quite old, having been developed many years ago. It keeps getting
improved, but just like "sort routines, we're living off of prior art.
AG
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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