This is such a simple stupid question I know but I am sitting here just going in circles. For canon and nikon can someone please put the cameras in the right order. The model numbers have me totally confused as to which are the entry level base and up and which are the pro base and up. Does that make sense. I think that for the Nikons it's D40, 60, 80, 90 in the entry level series but where does the d50 and d70 that I keep hearing of come from?