Canon EF 17-40mm f/4L USM lens review: Popular high-performance option

DxOMark Lens


Introduced in 2003 the EF 17-40 f/4L USM was one of the first of the lightweight pro-level L-series zooms from the firm adopting a constant f4 aperture. Not only does that make the lens relatively small and more portable compared with the f2.8 varients, but it also helps keep it moderately priced. This full-frame lens is also popular with users when mounted on APS-C cameras where it’s the equivalent to a 27-64mm. Like other L-series lenses from the company, the EF 17-40mm f/4L has a high grade optical construction consisting of three aspherical lens elements and even adopts a Super-UD glass element, an expensive glass type usually resevered for more esoteric lenses in the range. The 12-element 9-group construction allows a closer than usual minimum focusing distance of 11.02” (0.28m). It weighes 1.05 lb (475g) and measures 3.81” (96.8mm) in length, and is available now for $839 


Tokina AT-X 16-28 F2.8 PRO FX Canon 849 22 17
Canon EF 16-35mm f/2.8L II USM 1399 22 14
Canon EF 17-40mm f/4L USM 780 21 15
Canon EF 16-35mm f/2.8L USM 1674 20 14
Sigma 17-35mm F2.8-4 EX DG Aspherical HSM Canon 350 20 11
Canon EF 20-35mm f/3.5-4.5 USM 299 19 14
Sigma 17-35mm F2.8-4 EX Aspherical HSM Canon 700 19 11
Sigma 12-24mm F4.5-5.6 EX DG HSM II Canon 1400 15 12
Sigma 12-24mm f4.5-5.6 EX DG Canon 840 14 8
Best performing wide angle zooms on the Canon EOS 5D Mark III (prices quoted are prices at launch)

Canon EF 17-40mm f/4L USM lens performance: Very good sharpness, particularly at the wider-end

The Canon EF 17-40mm f/4L USM achieves a high ranking for an ultra-wide angle lens with DxOMark score of 21 points. Peak sharpness at 15P-Mpix is perhaps a little behind the latest designs but it’s still very good. Like so many zooms, it’s better at the wider end where it has good uniformity, even wide-open.  

At 35mm and above, sharpness drops somewhat at the maximum aperture, particularly in the outer field but that improves steadily when stopped down, with peak performance at f/8-11. Chromatic aberration is well reasonably controlled, particularly from 24-40mm but it’s evident in the extreme corners at 17mm. However on an APS-C camera with its smaller sensor CA isn’t an issue, and that’s pretty much the same for vignetting

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).

Due to its more glamorous sibling this modest lens is often overlooked though it’s well known for its high-performance by Canon users. As a small, light, highly portable zoom it would make a great choice for travel, landscapes and general-purpose photography.  Although not exactly cheap at $839, if portability is a concern it’s a great alternative to the faster model.