Canon EF 70-200mm f/4L USM Autofocus Lens is a high-performance, L-series telephoto zoom lens combining lightweight construction with an f/4 maximum aperture.
The 17 - 40 mm F4.0 L is designed to be a high quality, lightweight lens for both film and D-SLR cameras. Other features include a constant F4.0 aperture and minimum focus distance of 28 cm across the entire zoom range.