Compatibility  Everything works perfectly on every digital Nikon, both FX and DX, and even on Nikon's cheapest digital D40, D40x, D60, D3000 and D5000.    It's also perfect on decent or recent AF film cameras like the F6, F100, F5, N80 andN75.    Optics  21 elements in 16 groups.  7 elements are of ED glass.    Diaphragm  9 rounded.    Ratio  1:8.3 (0.12x), not very tight, due to the shrinking actual focal length as you get closer    Close Focus  4.6 feet (1.4m), specified. 4 feet, 2 inches (50"" or 4.17 feet or 1.27 meters), measured.    Weight  3.4"" (87mm) diameter.  8.2"" (205.5mm) extension from flange.