Canon EF 17-40mm f/4 L Lens

Posted on 19 November 2005

(Updated on December 28, 2011.)

The Canon EF 17-40mm f/4 L is a core lens in my kit, covering the wide to ultra wide angle range on my full frame cameras. For my primary uses it is a great performer. It is almost always in my kit when I backpack, and I often use it for a range of other types of photography.

As I have written elsewhere, every lens has a “personality” that makes it more or less suited to different types of photography and different photographers. This personality is the result of the relative strengths and weaknesses of the lens. No lens is objectively “best” in all ways, so the real interesting question is how various lenses line up with your specific needs. With that in mind, here are some observations about the 17-40 that I’ve developed during years of use since I got mine in 2005.

Overall, the lens is capable of excellent resolution. Center sharpness is good at all apertures (leaving aside for the moment the effects of diffraction blur that will soften the image from any lens at very small apertures) and quite good when the lens is stopped down a bit. It is important to note that ultra wide zoom lenses (and even prime lenses) can have some issues with sharpness and other factors such as chromatic aberration and so forth. This lens is not immune to these “features” of ultra wide lenses, though it handles most of them quite well.
Corner sharpness varies depending upon aperture. In my experience, the lens shows noticeable corner softness at f/4. Whether or not this is a problem depends a lot on how you will shoot the lens and what your expectations are. I have used the lens wide open for street photography in closed-in spaces, and the soft corners simply added character to the shots that I liked. If you require something closer to corner-to-corner sharpness wide open, the Canon EF 16-35mm f/2.8L II USM could be a better choice if you mainly shoot low-light, hand-held, full-frame work. (Link goes to site sponsor B&H Photo.) However, if you are looking for an ultra wide zoom to shoot more static subjects from the tripod and you will use smaller apertures for larger depth of field, the 17-40 is just as good – and lighter and less expensive to boot. Stopped down a bit and on the tripod, the 17-40 produces excellent results.
The lens has a great reputation for resistance to flare, and my experience is in line with this. This is important in an ultra wide lens since it wide frame of view is more likely to include the sun or other flare-producing light sources, and because the shallow lens hoods that are required for ultra-wide lenses don’t really shade the lens much at all.
Build quality is just what you would expect in an L lens, and there is something about the compact and simple nature of this lens that seems to give it an even more solid “feel,” for whatever that might be worth. Along these lines, it uses 77mm filters, which are very common on other L zooms.

If you poke around on the net long enough, you’ll find posts that suggest that the 17-40 isn’t sharp enough or that the 16-35 is a better choice. This turns out to lead to some complicated issues, so let me take a shot at dealing with them

Is the 16-35 sharper than the 17-40? Yes and no. The 17-40 is just as sharp (or even a bit sharper) in the center at any aperture, though it is not as sharp in the corners at the largest apertures. So, “yes” if you mainly shoot wide open in very low light. But “no” if you mainly use the ultra wide lens stopped down while shooting from the tripod, for things like landscape and architecture.
Is the 17-40 poor in the corners. Again, yes and no. First, very few ultra wide angle lenses are great in the corners – this is pretty much the nature of the beast. (There are a few exceptions, but they tend to be very specialized and very costly.) Second, wide open the 17-40 is not great in the corners, at least in my experience. However, stopped down it is fine there. (Some of the reports of poor corners seem to come from a typical characteristic of many ultra wide “test shots,” which often include very close scene elements in the lower corners – and the issue is more about DOF than about lens sharpness.
If you shoot a cropped sensor camera, neither of these will likely be the best choice – more on that below.

On full frame, this lens complements either of the 24mm-xxmm L zooms. It does overlap their focal length ranges a bit, but I find that useful for several reasons. (I shoot the EF 24-105mm f/4L IS.) First, it means that I am a bit less likely to need to change lenses. Second, it means that I can sometimes stay away from the ends of the focal length ranges of either lens, and this can produce just a bit more image quality in some cases.

Some backpackers combine the 17-40 with a Canon EF 70-200mm f/4L IS USM lens (link to sponsor B&H) and then add a 50mm prime to “fill the gap.” I don’t do this, but I can understand how it might work well and save some weight and bulk.

Some photographers like to use this lens on their cropped sensor cameras. I used mine on a cropped sensor body for the first year or so that I owned it, but I’ve used in exclusively on full frame bodies since that time. In my view it is merely OK on cropped sensor cameras, but not a stand out performer. The main issue is that, in my experience, you end up caught between the proverbial “rock and a hard place.” The “rock” is the relatively conservative f/4 maximum aperture with its less than stupendous corner performance. The “hard place” is the issue with diffraction blur occurring sooner as you stop down on cropped sensor cameras – many feel that you would want to be cautious about stopping down much past f/8 for this reason on crop. This doesn’t leave you with a lot to work with: f/4 is a bit soft in the corners. f/5.6 is getting better but isn’t yet great. f/8 is pretty good all around. At f/11 diffraction blur starts to become a concern. In the end, you really have only one truly good aperture. Fortunately, cropped sensor camera shooters have a great alternative in the Canon EF-S 17-55mm f/2.8 IS USM Zoom Lens. It provides better large aperture performance, a wider range of apertures at f2.8, image stabilization, and a larger focal length range. For this reason, I tend to recommend it over the 17-40 for cropped sensor shooters.

Almost-bottom line: In some ways, this is almost as much a post about options for covering this focal length range as it is about the 17-40 f/4 L itself. It is also a good example of the fact that there is no one “best lens” in a general sense, but that it is really about which lens is right for your particular needs. With that in mind, a quick recap of three options along with some general ideas about situations in which any of them might be a best choice:

If you use a full frame camera, mostly shoot from the tripod, and tend to favor smaller apertures for greater depth of field and other reasons, then the 17-40mm f/4 L could be the best choice for you. This is the lens I use, though I choose to augment it with some large aperture primes.
If you use a full frame camera and often shoot handheld in low-light situations and thus need to use larger apertures, the 16-35mm f/2.8 L II could well be the best bet for you. Of course, it can also do much of what the 17-40 will do, though with a higher cost, smaller focal length range, and greater weight and bulk.
If you shoot a cropped sensor camera the EFS 17-55mm f/2.8 IS is probably a better choice than either of the L lenses for you – with its excellent optical quality, f/2.8 aperture, image stabilization, and larger focal length range.

Bottom line: The EF 17-40 f/4 L is a great lens for full-frame photographers who want a versatile ultra-wide angle lens for shooting large DOF subjects from the tripod, including subjects such as landscape and architecture. Its lower cost, smaller size, and lighter weight are bonuses – the latter two especially so for those who work while traveling on foot.

This lens is available from site sponsor B&H Photo, and your purchase though links at this site help support the blog. If this information was useful to you in making your decision, please consider purchasing through the following link: Canon EF 17-40mm f/4 L at B&H

In addition to the Canon EF 17-40mm f/4 L, other lenses mentioned in this article and available from B&H include:

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