The fact that RG finds the camerat to focus acdurately when the focusing is first tripped, means to me that the problems are with the other functions, not the focusing. The problems are with the computer diddling around after first frocus is achieved. But first focus seems quite super.
That would be good enough for me, because I don't use any of the follow-the-subject-automatically junk. With my EOS-1Ds Mk II I focus each shot individually with one sensor and would never trust a machine to follow-focus something moving.
If I wanted a movie camera, I would buy one.
The point of photographing a moving object like an athlete, a soccer match, a theater or dance production, etc., is to get the right shot at the best moments in the sequence. Not to just mechanically follow the sequence at fixed intervals, which could easily miss the optimal moments.
In the manual-focus days, I did plenty of photos of dance sequences and moving subjects (not sports) getting just the right shots in each sequence, focusing individually (manually with a Messraster, see www.anstendig.org
). That, a machine could never do for me.
And it seems that the more sensitive and fast they make the auto-focusing, the more it picks up on things a human being would ignore, and thereby the auto-focusing messes up. It even picks up on temperature/heat-wave movement, which the human would ignore.
Also, using a single sensor and placing it on the person's body and not the face is a huge misunderstanding of how then placement of the plane of focus works in a photo. The sensor should have been on the face, preferably the nearest eye, if the sensor is small enough, which most are not.
And with that camera's stated first-focus speed, there is no problem manually re-pressing the butto every time one wants the shot. If you choose your shots while they are moving, you will probably get a larger percentage of best, most telling shots. And your focus will be just fine, if what GB says is true abotu the camera's focusing speed when the button is first pressed.