I have the opportunity to shoot field D1 mens athletics for no pay. I've been ready for a camera upgrade for awhile. I currently own a D90 and it has never been a pleasure to use. I have managed with acceptable images but I don't get the critical shot due to the frustrating focus on the D90. I use the 70-300 lens. Knowing this will be a temporary requirement I'm trying to get the best equipment for the job. It doesn't hurt that I love shooting sports. My other photo goals are social events, portraits, stills-macro. It makes sense to stay with APS-C sensors for the crop factor but I want the best focus system I can find with high ISO capabilities. I'm really nervous about Nikon and thinking about switching to Canon. I don't have a lot invested in lenses and plan to purchase better glass so it is the right time to consider Canon over Nikon. Sports photography for me will certainly be a compromise in equipment. Can someone help me figure out the best compromise? I'm willing to wait for a camera body and just purchase glass but then I will be tied to Nikon. Nikon choices are DX - D7100, FX - D610, D800, D4 being way too pro for someone not getting paid for their work. Canon choices: CMOS - 7D, 70D FF - 6D, 5D MKIII Then the compromise on lenses. The obvious choice for crop sensor body is the 70-200 f2.8 for either brand with an extender but I've heard mixed opinions on using an extender. Some lens parameters for consideration: Sigma 120-300, Canon 100-400 f4.5-5.6, Sigma 100-300 f4 This is not easy to resolve. Anyone have a hobbyist set up that has worked for outdoor big field sports? Hope to hear some success stories. Thanks!