Just to add, in case you weren't clear on this, micro-AF adjustment is for adjusting the camera with a specific lens mounted. The issue is that the positioning of the mount is never going to be exact for every body and lens, it's always within a certain tolerance. Using the micor-AF adjustment allows you to set the focus for that body and lens combination (the camera should detect which lens is mounted and recall the settings for that lens, I think some go just by model while other cameras will read the serial number as well) and, in theory, you should get much more accurate focusing.