Hello, I dont think heavy lenses (24-120 on an F70) is a reason to change bodies (towards the F90x). The only thing you might consider is getting a tripod for the lens. Ever wondered how much those 300/4 or 300/2.8 weigh, comapred to the 1.2kg F5 (ideally) or 800g F90x they are mounted on? Rest assured, I also use a 135/2.0 (600g or so) on my FM2 (500g), without much problems RObert
