F5: Is a decent manual focusing screen difficult to find? I'd probably get AF lenses anyways but I'm exploring some MF options. 20mm: I have a 20mm f3.5 UD but I do not think it is that great...atleast not at close distances and wide apertures. Would the 20mm f2.8 AF-D/AI-S be a noticeably better lens at close distances? It has CRS but ultra wide angles are difficult to design, to begin with, so maybe that is wishful thinking. I'm tentatively thinking of selling off my F + 20mm f3.5 UD for an F5 + 20mm f2.8 AF-D. I would then add a 50mm Finding a good/cheap 50mm is easy. I want the F5 because I can benefit from the heft, vertical release, and MLU on the F5 over the F.