Originally posted by Clavius Yes, during LV it moves constantly, and in "normal" use it is only activated during focussing and pressing the shutter.
For normal use the sensor is only moving after shutter button is pressed.
Quote: Can you explain why the short timespan translates to a smaller requirement in sensor movement? And can you explain why pre-LV Pentax DSLRs also had the 3mm sensor movement then? And, for the last time, why do DA lenses have an image circle that much larger then APS-C requires then?
As camera shake is low frequency (usually 1-10hz) it does not take very fast shutter speed before the sensor movement when the shutter is open is much less, than full movement when using LV/video.
As I said before, the extra movement is needed for accelerating the sensor before the shutter opens, but it does not matter if this movement is done outside the image circle of the lens.
I'm not sure why image circle vary so much on Pentax APS-C lenses, but I doubt it has anything to do with SR. But you will probably also find that most FF lenses have a image circle that is much larger than FF.