OK, another question.....how do you decide what f number to use if you are shooting in Aperture mode? Obviously I know that if I want bokeh +++, I dial it to the lowest f number. But how do you choose your numbers in between? Is there some kind of guide with regard to f and DOF? Am I correct to think that you get a certain DOF in terms of cm, with regard to certain f? Is there such a thing and is this kind of correlation correct on the ground? Thanks!