The last Lumix camera I had (it's been a few years - a 720p model) did the exact same thing whenever I zoomed in or out - it momentarily went out of focus. This always bothered me, so I went with Sony cams instead. I'm really interested in getting a 4K camera, and this FZ1000 footage looks amazing during the static parts. But I'm concerned about the momentary out of focus thing and I saw in comments for one of the videos that you said blur was caused by bass rattle of the image stabilization system. I didn't think that would happen while the camera is hand-held because your body would absorb the bass. So unless your somewhere where the bass actually shakes the structure on which you're standing, you should be able to avoid that bass rattle. It sounds like you're saying it shakes the camera's image stabilization and there's nothing you can do about that (i.e., tripod, cushioned base, etc.).