Why do so many say great depth of field, when they are talking about lenses with large aperture?
Most lenses have “great” DOF. Large aperture lenses don’t have “greater” DOF then say lenses with smaller max aperture. So what do lenses with large aperture give you? They give you shallow DOF(wide open, or close to it) and the ability to separate the main subject from the background. The blurry part of an image is often referred to as bokeh. The quality of the bokeh, is a matter of taste or preferences. I personally like the bokeh from Carl Zeiss, Leica, Fujinon, to name some.
Here are some examples of “great DOF” or as I prefer, shallow DOF with some nice bokeh 🙂