I finally upgraded from my T2i to a 7d mark ii. I've been on a DSLR photo hiatus. Actually shooting and editing tons of video with my GoPros and other POV devices. I was shooting my son's basketball for years, but now he is in drum and bugle corps world and didn't really have the camera or lens to get the kind of photos I want. I'm also surfing more and have been wanting to take pictures of a bunch of my buddies. After a lot of research reviews and reviews I bought a new Sigma 100 - 400 mm 5.6. I figured with my crop the 150 - 600 mm equivalent I'd have the reach I needed. Most of the photos I'll be taking are in daylight so the 5.6 would be fine. I really know how to dial in the T2i from years of shooting in poorly lit gyms, so my first shots with the 100-400 mm on my T2i were pretty good. SOME were good... but getting the single focal point locked in at 400 mm was a little tricky. Plus the fps was slow. The subject surfer would change direction and I wouldn't get the transition. Big gaps on the continuous fast action. I found a 7d mark ii in good shape, well cared for, and about half shutter life for a fair price. Okay... this is a seriously better camera than I'm used to. A little intimidated, but not totally lost in shooting manual. My T2i didn't have 6 tracking sensitivity modes and so many AF options. Questions: Shooting surfing will be mostly at 400 mm because it's a reef break that's way out. I use a mono pod. With this set up what would be the best AF settings? ISO? Shutter Speed? Should I get a 1.4x or 2.0x teleconverter? Do I really need a tripod? Here are a few sample shots. One at 100 mm and one a 400 mm.