One of the better reviews out there: "Any of the modes worked well with static subjects, although users should keep in mind when using the auto select or zone methods that all AF points in the selected zone are used to acquire focus and will tend to focus on the nearest subject. For moving subjects I found that AF point expansion worked best - but only after some trial and error. In addition to simply selecting the AF point expansion mode, I ultimately ended up adjusting the AI Servo tracking sensitivity to slow in order to get the best results."Any of the modes worked well with static subjects, although users should keep in mind when using the auto select or zone methods that all AF points in the selected zone are used to acquire focus and will tend to focus on the nearest subject. For moving subjects I found that AF point expansion worked best - but only after some trial and error. In addition to simply selecting the AF point expansion mode, I ultimately ended up adjusting the AI Servo tracking sensitivity to slow in order to get the best results.   Link