At 11:04 AM 12/21/2008, Johnny wrote:
>The auto-focus on Canon DSLRs, and I suspect also for Olympus, does
>not use what I would call a feedback system. The phase detection
>system takes one look, makes a calculation as to front or back focus
>and amount of focus error and then instructs the lens as to direction
>and amount to move to correct the error. The focus isn't re-checked
>after the lens reacts to the initial instruction. However, at least
>with Canon, the lens does have a closed loop where it verifies that
>the instructions from the body was accurately carried out. If you
>have any references that indicate that Olympus does use a feedback
>system I'd be interested in reading them.
The one question I have in my mind is when I manually focus the
lens, I get focus confirmation in the sensors, which to me indicates
that the lens is periodically sampling Focus and can do some closed
loop AF or confirmation. Creating a piecewise system. But this is
only conjecture on my part.
Wayne
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