focus.  D.W. Griffith (qv) convinced his most trusted cameraman, G.W.  Blitzer , to fade out the background when the three gangsters walk  towards the alley in the opening scene. During this era a cameraman  was judged on how sharp and clear his picture was, so Griffith had  to take him to an art museum and show him how the background was out  of focus and the characters were in focus to convince him to do the  effect on the shot. The focusing method is still used today.