I have been hearing from lots of people that the some best lenses ever made are the older generations of nikon fixed zooms. I heard that they are extremely sharp and reliable and well worth using. Unfortunately the shortcomings of my D40 are starting to show because most of these lenses will not autofocus with the camera. Also I want to use an SB-600 off-camera with TTL, something I apparently cannot do on the D40. Are the lenses really worthwhile? Would it be a good idea to sell my camera and purchase a D80? Would I even possibly end up saving money on lenses since I can use older ones? Also, what about the D70? I heard its one of the best cameras nikon has ever made. Does its flash have commander mode?