I have tried focus charts, lining up batteries, sw such as focal Web,,, and have decided I don't like any of these options. I've found I go into my yard, set aperture wide open, single point center focus. Setup a tripod 45 degrees to a post on a wooden fence. Focus on the post and shoot. Zoom in on the post and see if it is sharpest in front of, behind, or on the post. Adjust af fine tune until focus is best on the post.