Review – Canon EF 17-40mm f/4L

canon1740review - Review – Canon EF 17-40mm f/4L

Review – Canon EF 17-40mm f/4L
Discuss the Canon EF 17-40mm f/4L

Canon’s current and undisputed king of wide-angle zooms is the 16-35 f/2.8 L II: it’s the best as far as image quality, build, and speed of glass are concerned. But what if you were on a bit more of a budget? You could stick with your camera’s kit lens (if it had one), though full-frame users start at about 24mm and almost every crop body kit lens are EF-S, meaning it won’t work with your full-frame camera if you choose to upgrade later on. The latters’ variable apertures also aren’t very appealing. Thankfully, Canon likes to offer us, consumers, alternatives like the Canon 17-40 f/4 L. Lighter, cheaper, and nearly as well built as the 16-35, you can have your red “L” ring and still have enough cash left over to buy a flash. Of course, this lower price does come with compromises, and it’s up to you to decide if they’re worth it.


The 17-40’s all metal body is the first qualifier of a well built and durable professional lens. I have dropped this lens on the ground more times than I care to admit and it has seen its fair share of service calls, but never has the construction been more at fault than I was. The 17-40 is about 150 grams less in weight than the 16-35, much of which, I assume, can be attributed to the size of the glass in the latter. I’m happy that the Canon 17-40 offers a 77mm filter thread even if the front lens element is smaller than that, as it keeps my ND & polarizing filter costs low.

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The lens focuses internally, but there is some movement at the front element which means true-weather proofing can only be achieved with an additional filter. A rubberized base helps keep it dry on the camera-end and, like all L lenses, it comes with a low-profile lens hood.

I’ve always found this lens perfectly sized to my hands, so while the focus and zoom rings aren’t particularly wide, they suit the size of the lens. I’ve also always found focusing on this lens to be accurate and fast. Perhaps accuracy is relative, as the depth of field at these apertures is pretty deep and it’s hard to create a blurred out background without being at the minimum focus distance of 1 foot.

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This is the largest area of compromise with the Canon 17-40 f/4 L. Wide-open, the lens vignettes, it is subject to distortion across the focal range, it is prone to chromatic aberration (fringing occurs especially at the corners) and it isn’t particularly sharp until stopped down to f/5.6. In fact, I rarely, if ever, shoot it at f/4. Thankfully, 17-40mm is a focal range that can be reasonably hand-held at slower shutter speeds, and the advancement of high-ISO capabilities makes this less of a concern than in previous generations of camera bodies.

Edge sharpness is tricky on wide-angle lenses, especially on a zoom, so it’s not necessarily uncharacteristic for a lens this versatile to make compromises in those areas; it’s just that better alternatives are available. Canon’s 17mm f/4 Tilt-Shift as a well regarded sharp wide-angle lens would, of course, be ideal at that focal range, but we can’t all afford that one either. The 40mm f/2.8 pancake lens would make an incredible accessory at that range being so light, small and quite sharp wide-open at f/2.8 (and may still, even owning the 17-40). Distortion is also very noticeable if you’re looking for it, or if you’re shooting straight lines like in architecture photography. I now frequently use Lightroom’s lens profile correction before working on an image further since it’s less of an issue when I’m shooting environmental portraiture: I correct to taste. Even then, though, I find myself straightening and warping images further in post.

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Who’s it for?

The Canon 17-40 f/4 L was my very first lens. Ever. I bought a rebel XT and on the advice from a friend, I skipped the kit lens (which was terrible compared to today’s kit lenses) and went straight for a more versatile, full-frame compatible, L lens. It works very well on a crop-sensor body; the apparent focal length comes to 27mm-64mm which is comparable to a full-frame 24-70. Since most of the poor lens’ characteristics are at the edges, you avoid that on the crop as well. I would also argue that, when starting out, we’re not really looking for a lot of the pixel-peeping flaws we notice after a bit of experience, and f/4 is only soft when you compare it to something you already know is sharp. It’s a matter of perspective. Therefore, buyers of the Canon Rebel, 70D and 7D series should have a serious look at the 17-40 as their “middle” lens.

<Michael Taylor>5DMKII, 1/250th f/8, ISO 250 19mm

I’ve used this lens for pretty much every type of shoot I’ve had to do professionally, and many more before that. Photojournalists can use it to cover outdoors events, and I’ve used it with an on-camera flash at parties since shooting at f/5.6 is a good baseline for getting a group of people in focus, where f/2.8 would not. While Wedding photographers may appreciate the shallow-depth of field created by a wider aperture, 17mm is, in many cases, still too wide for much of the work you’ll do on location. Why not save the money and instead of buying the 16-35, invest in a solid 35mm Sigma prime , and have the 17-40 for backup or more scenic shots or “emergencies only.”

If you can’t afford a tilt-shift lens for architecture and interiors, the 17-40 on a full-frame camera offers a versatile do-it all. It’s great for me when I need something other than my 24mm tilt-shift. The 17-40 dutifully covers a tight space or helps me get a slightly different focal length without me having to lug around my 24-70 f/2.8 L. Since many of these shots are stopped down to more or less f/11, sharpness and vignetting aren’t issues, and the distortion is quickly corrected in post.

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Landscape photographers would also benefit from this light and quality addition to their kit. Why get f/2.8 if you don’t need it? Like all things, wide-angle should be used intentionally and doesn’t suit every situation, but when the conditions are right the results are worth it.


Much of what I wrote about this lens is in direct comparison to the 16-35 f/2.8 L II. Why not? When looking at a wide-angle lens, these are the two choices of lens that are most prevalent to a photographer. If budget and weight isn’t an issue, then the 16-35 trumps the 17-40. But if you’re like me and most people I know, you might need to weigh your purchases a bit more. I consider the extra 1mm from the 16 to 17 and 5 from 35 to 40 to be insignificant; my qualifications are based on aperture and quality of glass. I have no qualms with shooting consistently at f/5.6 or higher and, again, I only notice the distortion (though it’s obvious once you do the correction) when I’m shooting interiors. I personally don’t see the jump from one to the other worthwhile, but your needs may be different than mine.

I think the shift from a crop to a full-frame sensor camera can also come as a drastic shock with a lens like this. Everything changes and 17mm may be too wide for you. I know I quickly switched to my 24-70 after making the leap and it took me several months to find appropriate uses for such a wide lens.

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If you need a high quality, full-frame compatible wide-angle zoom lens, but can’t afford the Canon 16-35 f/2.8 L II, the 17-40 f/4 L is a worthy second best.

Purchase Options:


  • Light, versatile wide-angle zoom
  • Great on APS-C crop-sensor cameras
  • Great value L lens


  • Heavy lens distortion that requires destructive software correction
  • Soft wide-open at f/4
  • Fringing at the edges (full frame)