Shocking insight: AF is not a closed feedback loop!

Started Jul 18, 2003 | Discussions thread
Ben Strasser Senior Member • Posts: 1,763
Aah, but the lens needs to know which direction to move...

or start moving and this can only be done if the camera knows where the lens is in relation to where it has to be( feedback or closed loop). The only way around this to drive the lens in one direction until it stops then reverse the direction to the other stop (re-calibrate) then issue a blind step command to the calculated focus point. Canon lenses do not do this.

Mishkin2 wrote:

It is open loop - to move or not to move depends on the comparison
of the signals from AF sensor and lens drive quantity detector.

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