Take three photographs of a scene with depth to it, first at a wide-open aperture, then at a mid-scale aperture, then at a small aperture. Focus on the same central point. Observe the areas of sharpness in the resultant images.
Canon EOS 650D with EF 40mm f/2.8 STM lens
Very similar to previous exercise: I lined up a set of five condiments/jars from the kitchen cupboard, staggered in a slight diagonal line so that each was visible in the viewfinder. I chose the middle jar as the focus point and did the three shots at f/2.8, f/9 and f/22.
With the widest aperture, only the coffee jar in the middle is sharp, with readable text and defined edges:
With a mid-range aperture setting, the honey on the left and to a slightly lesser degree the salt on the right both fall into the sharp zone while the two items on the outside remain blurry:
At the smallest aperture the entire image is sharp enough to make out the text on all of the labels, and the wooden surface on which they are placed shows its grain pattern.
What I’ve learned:
This exercise was good for demonstrating a concept that I was familiar with, that of controlling the depth of field using aperture settings. The two extreme examples can have specific applications, such as bringing focus to one part of the image (widest aperture) as in a portrait or a macro shot, or drawing the viewer’s eye in through the image foreground->centre->background in more of a narrative way (smallest aperture), as you might for a landscape shot with a great deal of depth to it.