Is there a site anywhere that explains to NOOBS what different focal lengths of different lenses are used for? For instance, I know that my 18-55 is general purpose and even though my camera has a macro setting, it can only get so close. I know that the 55-200 would be the complementary zoom to the lens that I have, and I think that a 70-300 would be almost the same, but zoom further with a gap I probably wouldn't notice between the 55 and the 70.

Other than those deductions, I am still confused on all the rest. For instance, if I want a lens that just does macro (I assume this would be a prime), what numbers do I look for? My guess is that I look for a very small mm number, but then I see Nikon 105mm f/2.8 Micro and that screws me up. Is it due to the f/2.8 that it does macro when my shorter 18-55 won't? I don't get it. I need a chart showing what lengths are desireable for what shots.