I think this is the right place. So, people talk about Back Button Focus, and are often quite evangelical about it. I've tried it, and I'm clearly missing something. I tend to shoot in AI Autofocus on my 7dii, so when I want to take a shot, I focus on the subject (half hold the shutter down), and wait until the composition is just past what would have been good, and then I finish my click. If I'm in repeat-shot mode, I'll then just hold the shutter down and the camera follows the object in focus based on the relevant tracking options. What's different about back button focus (outside of when the exposure is measured)? It's one of those topics I've read up on, watched videos on, and tried, but I'm still not sure I understand what I'm missing.