EF15 mm f2.8 Fisheye
This is one of the most fun lenses Canon has ever built. Aside from its impressive 180° angle of view (measured diagonally across a 24 36 mm, 35 mm size sensor), the inherent ability of this lens to distort both foreground and background creates images that are uniquely interesting. Wide-angle lenses are capable of more depth of field than normal perspective or telephoto lenses. Thus, at small apertures, it’s possible to get what appears to be sharp focus from the closest working distance (0.2 m/0.7 ft in this case) almost to infinity. As with any wide-angle lens, but certainly true of the fisheye, distortion is minimized when the horizon is framed at the center. Note that the 15 mm Fisheye has an effective angle of view of 24 mm with the Rebel.