For my 50th birthday, my wife(and business partner) is taking us to the Southwest US to play and shoot photos. She rented us a couple 500mm MkII's for the trip. As you know from my collection at the bottom of my profile, we shoot with good old 300mm f4L IS's and the 500's are gonna be a giant and exciting leap forward for us. Can you offer any advice for us? We've got insurance, durable tripods etc. but more like field advice. We're wildlife shooters and any hints or tips would be greatly appreciated. Thanx everyone.