Pentax's SDM is usually very quiet, at least the 2 lenses i have with it. At first i wasn't even sure the DA-300 was focusing until you see the image coming clear in the viewfinder.
But without the screwdrive and motor in the body, we wouldn't have the ability to use the older lenses that require screwdrive. And, it might not be so easy to engineer really small pancake lenses with an electrical motor embedded in the lens frame. (i'm not so sure about this last statement) So it appears that Pentax bodies may have to maintain screw and SDM drives for some time to come.
I'm not sure, but i doubt that the micro 4/3s cameras and the Sony NX camera have sonic motors in their lenses.
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