Canon EF 17-40mm f/4L USM lens review: Popular high-performance optionBy Kevin Carter - Monday January 13 2014 Lens Review
Canon EF 17-40mm f/4L USM versus Canon EF 16-35mm f/2.8L II USM both mounted on Canon EOS 5D Mark III: Competitive performence
When compared against the $1,699 Canon EF 16-35mm f/2.8L II USM, the smaller, lighter f/4 model holds its own.
In fact the two perform at a similar level. The faster lens is a better performer at 35mm but the 17-40mm has more uniform sharpness across the field and marginally higher peak sharpness (albeit at different settings between them, and a difference of 1P-Mpix is trivial in real world terms).
The 16-35mm f/2.8L even has slightly higher levels of lateral chromatic aberration covering a larger area at its widest focal length, though levels are very low by 20mm. That’s quite an achievement although it’s worth remembering that the 16-35mm lens is both slightly wider and a stop faster (or just less when comparing Transmission).