Focus!

If you are worried about your technique, not the camera, being at fault then here are some good references for you to use to improve your technique.

First is an excellent list of Canon 7D articles and videos TTMartin posted in this forum.

http://forums.dpreview.com/forums/thread/3376410

Then there are these.

DSLR Camera Focus Tips - YouTube

Joe McNally - Da Grip - YouTube

Don't recompose!

Depth of Field Table

Online Depth of Field Calculator

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Living and loving it in Bangkok, Thailand. Canon 7D - See the gear list for the rest.