The Nikon 10.5mm 2.8 is a full-frame Fisheye, meaning it will provide you with frame filling images with a 180 degree diagonally picture angle on a DX sized Nikon DSLR. It was made exclusively for the Nikon DX format cameras, but with the introduction of the Nikon FX sized DSLR's this lens can also be used here in either DX crop mode or in FX mode.
In FX mode you will not be able to fill the frame, but you are rewarded with almost a 200 degree field of view on close focus. A modification needs to be done to the lens to take full advantage of this on the FX cameras(basically you need to saw off the lens hood). If you are serious about snow/skate photography a fisheye lens is a must to have.