The lens uses a rear focusing system, high-speed CPU, and a powerful ring-type USM with revised electronics for faster, more responsive AF. This lens continues the proud tradition of superior clarity optics found in L-series Canon lenses.
Ultra-wide angle lenses have always been in demand by architectural, corporate, and other top pro photographers.
This new lens features completely redesigned optics including 2 high-precision Aspherical elements and two totally new UD-glass elements. The result is superior image quality: better contrast and sharpness at the outer edges, and a reduction in chromatic aberrations that can sometimes be seen with high-resolution digital SLRs.
Its diagonal angle of view is an impressive 114