Canon has made a bold statement with its latest L-series lens, but is the world’s widest-angle rectilinear zoom lens all it’s made out to be? Michael Topham puts the f/4L USM to the test
Canon EF 11-24mm f/4L USM review
Canon EF 11-24mm f/4L USM – Image quality
Architectural and landscape photographers looking at this lens will be glad to read that it puts in a truly remarkable image-quality performance. For the finest wideangle results, users will want to use the lens at its 16mm setting and dial in an aperture of f/8-f/11 where sharpness is at its optimum. Inspecting the corners of images at this focal length reveals virtually no trace of barrel or pincushion distortion, and although the sharpness in the corners at f/4 isn’t quite what it is at f/8, it remains impressively sharp and is by all means usable when a faster shutter speed is required.
As is to be expected, pulling back the lens to its 11mm setting demonstrates some barrelling, but considering the generous width of this lens, I expected this barrel distortion to be far more severe. At the opposite end of the focal length, there is some evidence of pincushion distortion at 24mm, but this was more noticeable in our lab tests than in real-life images, and should be easily fixed by applying a lens profile as soon as one becomes available from DxO or Adobe.
Vignetting is apparent at f/4, but this becomes less obvious when the aperture is closed towards f/8
Inspecting the corners of the frame did reveal signs of vignetting – most noticeable at the widest end of the zoom with the aperture opened to its maximum. Unlike some lenses, though, the effect of this vignetting is tasteful and helps to draw the viewer’s eye gradually to any central subject in the image. Closing the aperture from f/4 to f/8 removed all signs of vignetting at 11mm, while at 16mm it was less visible once closed down to f/5.6.
Studying images for chromatic aberrations did bring my attention to some purple and green edges along high-contrast edges. However, these faint fringes of colour are well controlled and aren’t obvious unless images are viewed at a magnification of 100% or more. Again, these aberrations should be fixed relatively easily by applying a specific profile for the lens in raw conversion software, as soon as they become available.
The lens excels at the speed it focuses, locking onto subjects accurately and precisely with negligible fuss
Canon EF 11-24mm f/4L USM – Resolution
Subjecting the EF 11-24mm f/4L USM to a thorough lab test revealed that it produces a very impressive set of curves, with the sharpest results being recorded at 16mm with an aperture of f/8. These stunning sharpness figures continue at 24mm. The greatest fall-off from edge to centre sharpness was found at the widest end of the zoom, but the results remain very impressive for a lens so wide.
Canon EF 11-24mm f/4L USM – Shading
Our shading graphs show that the lens exhibits most vignetting when it’s used at its widest focal length, but the situation improves through the focal range. At 11mm there’s obvious vignetting at f/4, but this reduces by f/8. With the focal length set to 16mm, users will find they’ll only need to close the lens by 1 stop (f/5.6) to remove vignetting.
Canon EF 11-24mm f/4L USM – Curvilinear distortion
At 11mm barrel distortion is present in images, but as the zoom is gradually extended it soon dies away. At 16mm there’s virtually no trace of distortion whatsoever and only a faint sign of pincushion distortion at 24mm. Considering how wide this lens is, this is an astonishing distortion performance that’s up there with the very best.
