There's a school of thought that says that the 50mm f/1.2 Nikkor manual focus lens is the best Nikon ever made. I haven't used enough Nikon lenses to confirm or deny that but it is one of the best lenses I've ever used. In order to see just what the D5100 was capable of I took some shots with the lens mounted on the camera, again at ISO 100 on a tripod.
Firstly using this lens on a D5100 isn't easy. It only works in manual mode. In all other modes the camera tells you there is no lens on the camera. You can also only see the image via live view. There is also no exposure information and while the live view adjusts you have to get the exposure you want by trial and error or guesswork. Focusing is however relatively easy, with the magnification button on the back of the camera. Press it 3 times and you get a highly magnified view, easily good enough for precise focusing. Since the screen on the camera is really good this bit at least, is painless!
Just to say this is a bit cheapskate of Nikon. Only letting you get full functionality with the new AFS lenses is a bit mean. OK it may keep the costs down but other manufacturers make their cameras compatible with all past lenses, so why can't Nikon?
Anyway having got it to work I took the following pictures. They are all straight out of the camera jpgs. and on flickr, if you click View all sizes they are available at full resolution.
Again they are very good, but the anti-aliasing filter does do its work and makes the difference between this and the kit lens appear less than it actually is. This 50mm f/1.2 is spectacular when I've used it on m4/3 or my Leica M9, so I know just how sharp it is. Its a shame it gets a bit "neutered" on the D5100, but I can understand that for the market Nikon intend the D5100 for, that the Anti-Aliasing filter is as it is.
This is not to say that the sharpness isn't impressive, it is, and again these images show the excellent colour rendition of the camera. Whether its actually worth taking the trouble to use lenses like this on a D5100 is probably not that much of an advantage however, unless you want to use the very wide apertures it offers. Still nice to see what it can do with a really superb lens.