You will typically see that flutter in the auto focus in low light situations, it's because as the camera finds a point of focus and loses it, it's constantly refocusing. To be honest, manual focus will be your best bet prevent this from happening, but aside from that, good lighting will help keep that to a minimum. If you don't have control over the lighting, I would suggest keeping to manual focus. A lanc controller would help you adjust focus, though I usually just keep my thumb on the focus ring.
[Evil Ash Editor]"
You will typically see that flutter in the auto focus in low light situations"
I recently had this problem with my A1 and it was a well lit scene. I quickly flipped it to manual focus. I've see the focus pulsing in AF mode a lot. I only use AF when I'm really runnin and gunin hand held. I don't count on it when zooming in tight. Always go to MF then.