Similar to the previous exercise (Focusing with a set aperture), this one aims at showing how a subject changes when one modifies the aperture of the lens while keeping the focus unchanged. Here I used a zoom telephoto lens (set at 165 mm) so that the depth of field is shallow and the effect of changing the aperture easier to show.
In the above picture, only a couple of bottles are sharp, while the background and foreground are totally blurred. This draws directly attention to the bottles and their purpose.
With additional depth of field, background and foreground are more in focus. It is possible to distinguish the writing on the right hand side, thus adding an element to the reading of the photograph.
With more depth of field, the background becomes visible, also drawing attention. The photograph is now divided into three main zones: street, bottles and writing.