Focus Question - Please Help!!!

Hello,

I had some focus/tracking issues earlier this year and with football season fast approaching, I'm hoping the Canon community can help me.

In a nutshell, I shot youth lacrosse and baseball and noticed the focus often shifted away from the center AF point, usually to the left. I've attached a couple of photos to illustrate. It might be difficult to make out, but the player to the left is in focus and the player in the center is a soft focus.

Here are the settings I used:

Canon Mark III 1D with 70-200mm f2.8L

Manual (sometimes AV or TV depending on conditions), AI Servo, Rear Button Focus, Center AF point (most of the time) with inner 9 points assist.

C. Fn III (Moved AI Servo Tracking Sensitivity to the left)
C. Fn III (AF priority/Tracking Priority)
C. Fn III (4:1 Continuous AF Track Priority)
C. Fn III (8:2 Enable - Surrounding Assist Point)
C. Fn III (9:1 Inner 9 points)
C. Fn IV (1:3 AE lock/metering + AF Start
C. Fn IV (2:1 AF-ON/AE lock button switch - Enable)

I know with a single AF point and a narrow DOF, there is a good chance that some of my shots won't be spot on. That being said, is there something I should be doing differently?

Should I continue to use the surrounding assist points?
Should I continue to use the Inner 9 points?
What is the advantage of using the Inner 9 versus others?

What would you recommend for shooting football?

Any advice would be greatly appreciated!

Thanks so much,
Laura

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For Lacrosse I would use only single point with no assist. The reason being that the action takes place with lots of moving players with moving parts. All of your settings are how I shoot sports with my 1DmkIII.

The two photos you posted have players on different focal planes. Unless you stop down your aperture size you will not get the surrounding players in focus if they are not in the same focal plane as your target.

Quick thoughts. Don't use the 9 point assist, go to no assist or surrounding points only. Also use bigger DOF to get more in focus.

ajaffe wrote in post #14859024
The two photos you posted have players on different focal planes. Unless you stop down your aperture size you will not get the surrounding players in focus if they are not in the same focal plane as your target.

I agree, check the DOF
http://www.dofmaster.c​om/dofjs.html

if you want a sharper pic for a group of players (even though you focus on one player), you will need to use a higher (smaller) aperture

e.g.
random group lacrosse pic

XSi (450D)
Canon 100-400
F6.3
200mm
1/1250

I've been using center AF point only for about 4+ years with pretty good results with the 1dIII.

Remember, if the players are changing direction rapidly or decel/accelerating quickly, the camera may have difficulty keeping focus constantly. It sometimes helps to "pump" the focus button, obtain focus and then wait a second to start shooting.