
This photographer used a medium aperture because you can still see the background a little.
This photographer used a large aperture because the entire background is blurred and the subject is clear.

The photographer used a large aperture because the subject i clear but the background is really blurred.
This photographer used a small aperture because he wanted to get all the detail.
The photographer used a small aperture because he wanted the detail in the backgound along with the detail in the bench.
The photographer used a small aperture because he wanted to capture the detail in the hay bails, the clouds, and the trees.