Are Your Pictures Soft?
What is AF Micro Adjusting and why do I need it?
AF Micro Adjusting is a setting in newer higher end DSLR's that allows you to have your lenses calibrated to work efficiently with your body.
You need to have this done if you notice that your pictures are not coming out crisp and focused on the point you focused at, ie. the subjects eye. If you focus on the eye and the nose or the ear is in focus, you should have your lens/lenses calibrated to you body.
The problem seems to be happening more and more with the newer, "professional" cameras than it does with the less expensive consumer cameras so if you use a serious amateur or a professional camera, make sure your pictures are in focus they way you want. If they are not, then you should consider having your lenses calibrated, which is a service done most times, while you wait. The cost is $40 per lens per body, if you have more than one body.