Depth

This exercise consisted in finding a place where I could frame a shot that contained a close and a distant object. Once this would have been done, it had to be noticed that, when zooming in on the close object, the distant one was out of focus. Conversely, when zooming out while keeping the two elements in frame, the background one came into focus. That was because of the depth of field, which was increasing as zooming out. Furthermore, the objects appeared to move apart. 

The scene that I shot was the one below: