Task: Find a subject in front of a background with depth. Take a close viewpoint and zoom in.. Focus on the subject and take a single shot. Then, without changing the focal length, set the focus to infinity and take a second shot.
In the first image the image is clearly about the ironwork of the church which is clearly where the focus is. In the second it is less clear; is it the ironwork or the church? Both are reasonably clear although the focus seems to be beyond the ironwork. It becomes more difficult to tell what the subject of the photograph is.