This past weekend I payed around a bit with my prime lenses set at various shutter and ISO settings at f/4 and below. This example is a tweaked crop of the top of the old man cactus on our patio. When I took the shot the cactus was in full shade and the backdrop was a totally hot midday sunlit field. Obviously, the depth of field was VERY shallow. I used Photoshop to pull the detail out of the shadows which, in turn, homogenized the background. Why not?
Lens: Canon EF 85mm f/1.8 USM. 1/1000 second at f/2.8, ISO 400.
Canon T2i playing with extremes.