I've seen references to these issues here and there, but surprisingly few. So here's my frustration with Panasonic lenses. I shoot a lot of handheld run-and-gun stuff, and need to sometimes keep zooms. These lenses make a mess of that.    UMIX G VARIO 14-140mm f/3.5-5.6 (updated version but I have been told the original is the same) As you zoom in or out, the focus will flutter, causing a rather ugly effect. Once you stop zooming, the focus will settle back to where you set it. But the flutte