Field-test of the Canon EF 20mm f/2.8 USM Super Wide-angles lens. Users of Canon's manual focus FD lenses have two choices when it comes to the 20mm focal length, courtesy of the FD 20mm f/2.8 and FD 20-35mm f/3.5L zoom lens. When the EF lenses made for the Canon EOS cameras started to replace the FD series gradually from 1987 onwards, there was only one lens to choose from for those who wanted to use a 20mm focal length: from the EF 20-35mm f/2.8L AFD zoom lens, which has since been discontinued. Its successor is the EF 17-35mm f/2.8L USM zoom lens. In addition to this L-series version, Canon also has the reasonably-priced EF 20-35mm f/3.5-4.5 USM zoom lens meant for advanced amateurs, amateurs and beginners. The discontinued EF 20-35mm f/2.8L AFD and the acurrent EF 17-35mm f/2.8L USM zoom lenses created history in the sense that both are the first of their kind to utilize a constant maximum aperture of f/2.8 - a design that more or less reduces the professional photographers' reliance on using fast aperture, single focal length Super wide-angle and wide-angle lenses. The former has four focal lengths, 20mm, 24mm, 28mm and 35mm and the latter five; 17mm, 20mm, 24mm, 28mm and 35mm. Coupled with the constant maximum aperture of f/2.8 throughout the entire zooming range of these two lenses, it is no wonder that many professional users of EOS equipment have chosen them over the single focal length versions like the EF 24mm f/2.8 AFD, EF 28mm f/2.8 AFD and EF 35mm f/2 AFD wide-angles. Canon EF 20mm f/2.8 USM About the same size as the EF 14mm f/2.8L USM     Overall length when focused at infinity Does not change at closest focusing distance However, Canon had also introduced the EF 20mm f/2.8 USM, a single focal length Super wide-angle lens not long after the Canon EOS-1N made its debut. This 20mm USM Super wide-angle was soon followed by others, some of which are the EF 14mm f/2.8L USM, EF 24mm f/1.4L USM, EF 28mm f/1.8 USM and the EF 35mm f/1.4L USM. Why has Canon introduced a whole new fleet of fast aperture, USM wide-angle optics when both the professional and advanced amateur users have accepted its popular L-series zoom lens version? Because there remains a niche market to be filled, for those EOS users who prefer to use exclusively single focal length lenses rather than depending on zooms. There are a few advantages in using a single focal length Super wide-angle lens as compared to a zoom, which utilizes a similar range within its design. << Back to Main . 1 . 2 . 3 .