`Panasonic Bob' (Steve's Digicam, Panasonic forum, 30 March 2004)...
What you are hearing is a combination of two things -- both are normal.
1. The large lens body tends to amplify the mechanical noise from the internal gear drive.
2. The OIS lens element is suspended by two magnetic coils. At startup the coils are not yet energized so the element has some mechanical movement.
Item 2 is the same on the FZ1 though you don't hear it as much due to the smaller body.chiks (Steve's Digicam, Panasonic forum, 1 April 2004)...
I think panasonic, in its jest for a quick startup, provided a quicker extension speed, which invariably leads to a vibrating sliding motion. If it were a tad slower, it would not make this brrr...bzzz sounds upon startup