Those discussions, even though we may disagree sometimes, may get you thinking more about some things you are doing to see if you can do them better.
I will do more tests on this topic, not to show who is right or wrong. I've made couple of family shots yesterday, this time using dial to select the AF point. Some of them turned not so sharp?! I have steady hand ... but ...
I will do more tests, this time with tripod. Again, it will all depend on the situation, but I am talking of one of them: family pictures, like group of people.
When we have two or three person at the distance of 5-10 m and using 50-70mm focal length, the difference between the distance measured by center or any other AF point will not be of any significance. That is what camera in fact is doing: measuring the distance. How accurate the camera is in doing so, we can test buy marking the lens position and AF couple of the times at the same spot and distance. Good camera and good lens will show minimal inconsistence.
I was thinking of the other aspect and that is when, for example, left-most AF point is used for focusing lens sharpness, even though not significant, is still not as good as at the center. All the focusing is done at the highest aperture (say 2_8 so that sharpness difference may be even worse. Can that affect focusing accuracy (or speed) of the camera? I am not sure, but will do some more testing and post.
If anybody knows about some good link for reading on this topic on internet, maybe it can shown it here?