Focusing/Stabilizer Settings

I shot my daughters playing soccer two different days and noticed a big difference in the sharpness between the two. I'm using a 20D with a Canon 70-200 IS 2.8 lens. Both days the ISO was 400 with shutter speeds between 1000 and 2000 and lens set between 2.8 and 4.0

Day one I used One Shot focusing with the lens set on stabilizer mode 1 and it was handheld. I typically keep tapping the button to bring things in focus as I go.

Day two I all I switched was to AI Servo focusing, used the monopod and kept the lens on mode 1. Things were a lot softer with this setup.

Any thoughts? Should I have put the lens on mode 2? I hardly ever (never) use AI Servo either. Could that combo have made the focusing off?

Any input's appreciated.

Switch IS it off all together and deffo when on any kind of support, use AI Servo

IS does nothing for shooting with shutter speeds like you acheived

For soccer you should always use AI Servo and nothing else.

Gillespie - I agree with gazcoyle. IS is not intended for action sports. It is meant for camera shake, and your shutter speeds should render it useless, and it DOES lengthen auto focus times. Turn it off - many shooters actually tape over the switches with gaffer's tape to ensure they don't accidentally turn in on.

Also, AI Servo is THE mode for shooting sports, so why would you "hardly ever (never) use AI Servo"?

99/100 AF issues are related to operator error in how the camera is set up and/or how it is being used.

There are a ton of posts herein that cover the how-to's of sports photography, not to mention a sticky or two. Check 'em out.

Thanks.....I don't have a lot of time behind this lens and have not taken a lot of sports action...Your input is appreciated. Tonight's another game so more practice time for me.

And use center AF point with C. Fn 4-3 and use * button to focus in AI servo mode.