I am somewhat confused, when I first learnt to shoot stills I was told if I metered off white subject then I should open up 2 1/2 stops and black subjects close down 2 1/2 stops. To me this means that any thing 2 1/2 stops over your 18% grey is white and so forth. Some of the Kodak brouchures indicate stops higher than that 2 1/2, but which are not white (This is the photo reference shot with spot meter values across it). How does this relate to spot meter values when some stocks contain more than five stops of latitude? Am I looking at this the wrong way?