higher f stop means that you have a greater depth of field. think of the things that are in focus as a plane that lies a certain distance away from your camera lens. you can move the plane closer and farther away with the focus, and you can make it deeper or shallower with your aperture. high aperture number means that more stuff is in focus, but calls for a longer exposure time. low aperture number means that less stuff is in focus, but calls for a shorter exposure time. I'm loving your single exposure shots. they're way better than your HDR shots.