Hopefully I'm pretty specific enough on these questions that I don't get beat up on for starting another 70-200 thread. I have heard and read amazing things about the 70-200 2.8 IS MKII with the 2X TC III and decided that is the path I want to take. I picked up the lens last week and haven't taken off the camera since then. I keep hearing things like all the focus zones don't show up with the 2X and the AF don't work with certain bodies, so I want to know on my camera (60D) if that is true? I'd also like to know if there is a huge difference with the MKII or the MKIII? Any lens sample pages? I'm torn on this because I have found the MKII going for $240 down the street from me and think that for the price I might just get it, but I just want to make sure it's what I want. I hike and backpack a bit so I want to keep it light plus I just dumped a bit of money into the 70-200, so getting a 100-400 isn't a option. Mostly going to use this for animals and birds while hiking. Thanks for any help!