Canon 17-40 f4L USM Quick Field Review

According to Canon, the 17-40 f4 L is one of their best selling lenses. After having used one in the field for a week, I can see why. When I reviewed Canon’s 70-200 f4 L , I called it one of the best buys in their entire 64 lens system. Without any hesitation whatsoever, I can say the same thing about this attractively priced ($629.) L series wide-angle zoom.

The focal length of this lens is ideal for a wide range of subjects whether as a 17-40mm on a full-frame, 22-52mm on a 1.3x, or a 27-64mm on a 1.6 crop camera. The f4 aperture is fast enough for all types of outdoor photography. For indoor and event photography, you will need to use a flash or boost up your camera’s ISO speed.

At 1.1 lbs, the 17-40 f4L is neither extremely light or too heavy. It balances nicely on all of Canon’s DSLR camera bodies. The lens feels very solid and it is well built. I carried a 17-40L all day on a 10-mile hike and was never bothered by its size and weight. The lens is constructed of a hybrid metal and plastic compound with a polycarbonate barrel. The flat black paint finish along with the trademark L series red ring is very professional looking. The lens is weatherproof and sealed against both moisture and dust. Canon does recommend the use of a UV filter for complete weather sealing.

The 17-40 f4L USM is a two touch design with the focus ring positioned near the end of the lens barrel and the zoom ring located near the lens mount. Auto focus performance is extremely quiet and lightning fast. This is a true internal focus lens. Both the zoom and focus mechanisms are completely internal so there is no extension of the lens. In my opinion, one of the most impressive features of the 17-40L is its super smooth manual focusing and zooming controls. The manual focus ring and zoom control have large, textured, rubberized surfaces that are comfortable to use and fast to operate.

The 17-40L is a digital optimized lens, and incorporates Canon’s latest lens coatings. The design of the lens includes three aspheric elements and one Super UD glass element (Utra-Low dispersion). My test images were very sharp at all apertures, but best by f8. I think most users would be unable to see a difference in sharpness between this lens and primes when shooting in the middle aperture range. Color quality and contrast levels were both excellent, typical of Canon’s L lenses.

As a side note, in a recent meeting I attended hosted by Canon, their technical representatives stated the image quality of the 17-40L is every bit as good as both the old and new versions of the much more expensive and one stop faster 16-35 f2.8L.

I had just one concern bout this lens. Like many other wide zooms, the 17-40L showed a rather high degree of barrel distortion noticeable in my scenic and landscape photography. At the 17-24mm settings on my 1Ds full-frame camera, trees were rendered as bowed lines and the horizon was portrayed as a wavy rather than straight line. When I zoomed into the 26 to 40mm range, the level of distortion was much improved. For many types of photography, this distortion isn’t going to be a problem; however, architectural and landscape photographers should be aware of this phenomenon.

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