The results of disturbing backgrounds

Poor dog, she has a pole sticking out of her head on
photo no. 1 and white snow cutting her head into two in no. 2
-and the right way to do it...

The two following exsamples shows how an altered F-stop can influence on how the background is appearing

At the left: Aperture set on 16, at the right:
Aperture set on 2,8
Camerakit: Nikon D300 with AFS Zoomnikkor 70-200 VR