Andrew Kass , Nov 20, 2009; 02:38 p.m.
I was curious, when you are using AF-S ( single servo) is the camera only using one Auto focus point when using the dynamic
range auto focus selection). It occured to me that it could not be using the surrounding points since once in focus it locks. So how can
anyone use AF-S for sports?
David Haas 
, Nov 20, 2009; 03:12 p.m.
Andrew -
The two things you're questioning are related, but completely different.
AF-S does not limit your selection points, it merely limits / controls when the focus occurs.
With Single Servo the AF does not track the subject unless it moves BEFORE focus is locked. In Single Servo mode - once focus is locked, the camera will NOT focus track the subject, even with Dynamic AF turned on.
On the continuous - C - mode - tracking will continue until the photo is acutally taken. Doesn't matter if you're using 1 or 51 AF points.
The AF points control which portion or area of the frame are in focus or the center of the focus selection.
Typically sports shooters use AF-C and a single center point of focus.
Dave
Andrew Kass , Nov 20, 2009; 03:38 p.m.
Thanks. That was the clear explantion I was not able to find by googling it.
Francisco Disilvestro , Nov 20, 2009; 03:39 p.m.
In AF-S the camera focuses on subject in selected focus point only (dynamic area AF). It does not use the surrounding points.
I would suggest AF-C for sports. Another approach is to configure the camera to activate the focus only with the AF-ON button. In this way you can simulate AF-S by releasing the AF-ON button when you focus on your desired subject.
Robert K , Nov 21, 2009; 09:50 a.m.
