Squirrel camouflaged © 2012 Sue S Puetz

Today’s DSLR cameras can take all of the guess work out of making photographs, and they continue to improve. Given the number of options for selecting the focal point, auto focus is an option that can be used effectively in most cases. However, if there isn’t a nice clear, unobstructed view between the camera and the subject of the photo, the only choice is to manually focus.
The photo above was shot with a 200mm lens at a wide aperture of f/2.8 to capture every possible detail of the squirrel. If the camera had been set to auto focus, it would have been impossible for the camera/lens to know that the intended subject was the squirrel rather than the mesh of limbs between the camera and the squirrel.
Don’t be afraid to set your camera to manual focus. Practice often and with all of your lenses so you will be accomplished and confident when the shot requires it.