Test of Seven 50mm Lenses for Nikon. Good stuff. The $239 Nikon AF-S 50mm/F1.8g comes out really well.
As you can see, these lenses perform very differently at each aperture. If you shoot mainly wide-open and don’t need to go faster than f/1.8, the Nikon AF-S Nikkor 50mm f/1.8G is your best bet and was the sharpest of the lenses tested @ f/1.8. If you prefer a faster f/1.4 lens, the Sigma 50mm f/1.4 HSM EX DG is great, as is the Nikon AF-S Nikkor 50mm f/1.4G – both are sufficiently sharp at f/1.4 and sharpen up nicely as you stop them down. If you’re a landscape photographer, you’ll be stopping down most of the time; the Nikon Ai-S 50mm f/1.2 and f/1.4 were absolutely excellent stopped down and had the best contrast as did the Nikon AF Nikkor 50mm f/1.8D.