The main difference that nobody here as mentioned yet, is that the D40 (and D60) do not have AF motors in their compact, very efficient bodies. So these smaller cameras, in order to AF, have to use Nikon's AF-S (or AF-I) lenses, which instead have the required AF motor stuck inside them! Older AF lenses that are not designated as AF-S (or AF-I) can actually still be used on these motor-less camera bodies, they would just need to be manually focused, thas all...\Greywoulf