PHRubin wrote:
Today's cameras autofocus so well it is rare to need to manually focus. Unless you encounter those rare occasions, you may never want to manual focus. The technique is to live view, then magnify the view on the area you want in focus, then focus. Obviously, this is only good on stationary subjects. Micro photography is one case where it might be desirable, especially if one is taking multiple shots, each focused slightly different, then combining them for HiDef.
Live view uses the slower and quite accurate contrast detection in lieu of phase detection and can be another topic to examine! One area of research leads to yet another!