Originally posted by BROO That's pretty wide I guess? I assume that's a no?
Mistral is right. The thing about Fisheyes is not really the field curvature, but the amazing field of view your get with them. You can probably get an instagram filter that will give a fish eye effect, but it won't cover the real reason that people like ultra wide angle lenses. So, the Pentax DA 10-17 FE covers 180 degrees angle of view at 10mm, but the DA *11-16 only gives a 104 degree angle of view on an APS-C camera at 11 mm.
I don't personally like fisheyes a whole lot and prefer rectilinear projection (although at ultra wide angles even that can get a bit strange).