The trick with ultra-wide angle lenses is to keep the camera vertical to avoid any major distortion. This was taken with my Sigma 20mm f/1.8 EX DG Aspherical lens. On my DSLR I compared it with the Sigma 10-20mm f/4-5.6 EX DC lens at 20mm and the Sigma 20mm f/1.8 EX DG Aspherical is the clear winner: a lot less distortion (both are full frame lenses), sharper at all apertures and a f/1.7 to boot!
Kodak TRI-X at EI 1600, developed in HC-110 dilution D for 17:30 minutes. Agitation: 2 inversions every minute.