Canon EF 17-40/4L USM Lens Review

by Philip Greenspun; created June 2007

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Canon makes two high-quality wide-angle zoom lenses for full-frame cameras, the 17-40/4L reviewed here and the canon_16-35. In the digital era, the 17-40 has been overlooked to some extent. It isn't wide enough to be dramatic on a small sensor camera such as the popular Rebel series. It doesn't offer enough of a cost savings over the 16-35/2.8L to be interesting to the folks buying the full-frame sensor cameras. Our prediction is that this lens will come back into its own when Canon brings the cost of a full-frame body down below $1200. Until then, anyone with enough money for a 5D will probably simply buy the 16-35.

If you have a full-frame Canon digital body, don't need the extra f-stop of viewfinder brightness or available light capability, and want to save $700, this might be your next lens.


The lens design is of low complexity for a zoom, with 12 elements of glass arranged in 9 groups; Canon's f/2.8 prime wide-angle lenses typically include 10 elements of glass. Three of those elements are aspherical, which improves image quality and reduces the number of elements required. Thus, contrast can be as high and flare as well-controlled as with a simpler prime lens. Distortion will be a little higher.

Maximum magnification is 0.24x at a distance of less than one foot. With a full-frame camera, the smallest object you can photograph is roughly half the size of an 8.5x11" (A4) piece of paper.


Like all L lenses, the 17-40/4L is ruggedly constructed and resistant to water and dust. The included EW-83E lens hood bayonets onto the exterior of the lens, leaving the 77mm filter and lens cap threads free. The 17-40 incorporates a ring USM motor, which enables "full-time manual focus", even when the camera/lens are set to autofocus. This is very useful when using Custom Function 4 on an EOS body, which moves autofocus to the exposure lock button on the rear. You can focus manually if desired and, at any time, push the rear button to give yourself a shot of autofocus.

Weight is 500g, which balances well with Canon's mid-priced bodies. The medium-speed prime lenses are much lighter, however, e.g., only 185g for the 28/2.8.


The most likely alternative to this lens is the 16-35, which is somewhat heavier (640g) and twice as expensive. The highest quality alternative to any wide-angle zoom lens is a bag of prime lenses.


It isn't much lighter than the 16-35/2.8L. It isn't better quality than the 16-35/2.8L. It isn't dramatically wide on the small sensor cameras. However, if you want a high quality wide-angle zoom with a medium weight and a medium aperture, the 17-40/4L is an excellent value.

When Canon comes out with an inexpensive full-frame digital body, this lens will be part of a great traveling kit:

2018 Update: It has been 11 years since this article was written. The cheapest current Canon full-frame body is the 6D II, $1,600 at Amazon. No wonder most people just use their phones!



22m, f/7.1, ISO 100, 1/100th of a second (folks move pretty slowly in their caps and gowns on a hot summer day). The wide angle shows the newly minted PhDs (falcons and PhDs are the only animals that are regularly hooded) and the background of MIT's Killian Court.

24mm. With street photography, you need to lift the camera, push the shutter release, and put it down with a smile before people start throwing stuff at you. Chinatown, Manhattan. ISO 200 allowed settings of f/5.6 and 1/250th. Stopping down from f/4 increased the depth of field enough to cover focus errors. The faster shutter speed freezes camera shake and/or subject movement.

17mm. One of the joys of street photography is serendipity. I set up for a photo of this father, proud that he doesn't have to pay MIT $50,000 per year anymore, and the hipster skateboards through. The shutter speed of 1/80th wasn't fast enough to freeze the skateboarder, but maybe that is for the best since the blur suggests motion.

17mm. Everyone has long legs at 17mm. Downtown/Wall Street Heliport. Parking is about $50 per hour.

Two similar images of a handball game. It is tough to choose between these photos because they are both so bad. "If your pictures aren't good enough, you aren't close enough." Getting closer in this situation would probably have resulted in a serious contusion.

Image at left: 17mm.

Image at right: 40mm. I wish that the final ear in the frame had a mobile phone held up to it, but that's why street photographers throw out 99 percent of their images.

36mm. There is something about a gun shop in Manhattan that makes a photo interesting even at a boring point-and-shoot camera focal length.

17mm. Even at f/9, the background is not within the depth of field, which concentrates attention on the foreground circle of photographers.


17mm, f/5, 1/800th, ISO 200. Helicopters fly pretty low and the downtown Hartford, Connecticut airport is pretty big. The 17mm wide end of this lens enables the relationship among the airport, the river, and the highway to be appreciated.

17mm, f/10. Everything is in focus.

Text and pictures copyright 2007 Philip Greenspun. Unless otherwise noted, all images on this page were taken with a full-frame Canon 5D.