I know I've been MIA for a while now, putting some deals to bed, and buggered up my back badly (NEVER lift and twist at the same time - you'll pay for it!) but I have a question for the techies here.... In fairly simple terms, can someone pls explain to me why the Tokina 12-24 WA lens won't work on a full frame camera, as they say on sales websites. There's talk of the Fuji S4Pro being FF, that is why this is an issue for me - in case I want to upgrade later. If a lens fits on the front of the camera, why on earth would the CCD affect the lens' ability to work? I'm not getting my brain around that one???!!!