Another reason for changing focal length is to control depth of field (DOF). From: "Izzet" <izzet@vizo.com> > Karl, > > Then does it follow from here that > 1-The ONLY reason we loose resolution when we blow up an image on the > film is because of the grain and other impurities of the film itself, > and > 2-The resolution power of the optical system (lens) is infinite.
