The widest prime lens in the Canon catalogue is a real gem: the EF 14mm f2.8L II USM, now in an improved Mark II version, delivers ultra-wide coverage without any of the distortion of a fisheye. This is the lens to go for if you want to capture big skies, large buildings or expansive landscapes with superb quality. It’s also a valuable lens in cramped situations. Put it on a cropped body and it’s still pretty wide, but much less exciting. I wouldn’t recommend it to APS-C owners unless they were thinking of upgrading to full-frame in the future. But full-frame owners who love their ultra wide angle coverage will quickly become smitten, and it’s well worth spending the extra on the Mark II version. Compare closely with the EF 11-24mm f4L zoom though.