http://www.nikonchat.com/af-dx-fisheye-nikkor-lens/

D3100 Nikon lenses help?
Okay. I'm getting a nikon d3100 does come with a lens or do I have to buy one and makes an AF DX Fisheye-Nikkor 10.5mm fit?
The D3100 comes with a Nikon 18-55mm lens (if you get the kit). You can only get the body alone. AF DX Fisheye 10.5 mm fit any DX format Nikon (everything except the Nikon D700, D3, D3x / s) only autofocus on the D90 and above (not autofocus on the D3100), I suggest not get the lens right away. Rental for the first time to see if it will use
Nikon 10.5mm f/2.8G ED AF DX Fisheye Nikkor Lens