HSM vs SDM vs Screw Drive
An interesting question which i have no answer to and would love to hear peoples comments about it, however focus hunting is one thing i believe it is not, it often is due to low contrast of AF subject, and if the focus hunts anyway, from what i've seen it hunts so much that it is way beyond any mechanical tolerance level.
Oh and i i wonder about the old AF lenses without AF override, is there play in the manual focus mechanism at all like there is in most ultrasonic lenses, or is the play in ultrasonic lenses purely in the manual focus ring, or the interior mechanics.
If there is no play in the older AF lenses, that might prove there is some design reason, so that the play is minimized due to no ultrasonic motor.
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