The internal mics on any camcorder are most likely going to pick up the zoom, I suppose, but I haven't noticed it so much with my Canon HFM500.
Another observation about zooming: my experience with my particular Canon is that it has good low light performance when fully zoomed out, but the aperture closes down when you zoom in.
I have not used the Panasonics that Techqui mentioned, but I have seen them recommended by others.