Had this been shot with a _powerful_ electronic flash unit bounced off of the ceiling or a wall, you could easily have stopped the lens down to f/22 and had pretty deep depth of field, even at close distance. By powerful, I mean something like a $100-$249, 150 Watt-second studio flash unit that plugs into AC wall current and is placed on a light stand, or a powerful, handle-mount type flash of the "potato masher" style, like my old Sunpak 622 Super, or a big Metz 45 or 60-series potato masher. Don't worry about people cautioning you about losing sharpness due to diffraction at f/16 or at f/22: the bigger issue is depth of field, and getting enough to keep things simply in focus! When you shoot close-up like this cat shot, stopping the lens down to the smallest aperture (usually f/16, f/22 on some lenses, f/32 on most macro lenses) is the way most seasoned shooters approach things. Of course, you'll want your sensor to be clean when you stop down that far! Sensor specks look like pepper flecks when the lens is topped way down. Anyway...as waday mentioned, looking for clean, good backgrounds is a great idea when photographing cats.