I have a G3 and am trying to decide between the Olympus 75-300 Zuiko lens and a Panny 100-300. The Olympus sells for $899 new as opposed to the Panny @ $499.00. The Olympus lens is described as fast focusing. Will the Olympus fast focus on my G3 or does this only apply if mounted on an Olympus camera? Some of the Panny 100-300 reviews say that it tends to hunt in low contrast situations. I'm willing to pay the extra if the focus is faster. I am assuming that for $400 extra the Olympus delivers better quality images than the Panny 100-300.