I have a nikon d40. recently i started liking the looks of pictures taken with fisheyes. so now i'm really interested in buying one. i skate, and talked to some people on skate forums about which fisheye i should get and they told me that a 10.5mm would be best. i found some Nikon AF DX Fisheye-Nikkor 10.5mm f2.8G ED lenses on ebay ranging from $355 to $700. would this be a good lens to buy?