Canon EF 17-40mm f/4.0 L USM Lens Review:


Here is my first equipment review. It is not actually a review; I’d rather want to share my personal experience of using this lens. I have no intention to shoot test charts, because nobody shoots test charts, print them and hang the pictures of test charts on the wall in real life, and there are lots of places over the internet, where you can check out test charts. I will supply a link at the bottom of this review where you can check all these formal test results if desired. I want to share some real life experience here. All sample pictures shown in this review are processed for print. I don't consider this as a drawback, as I speak about practical applications, not abstract theoretical performance. In general, I prefer to use the best equipment, I can afford, and I usually choose my gear very carefully on a price/performance/handling/weight criteria. I don't like zoom lenses for several reasons, so Canon EF 17-40mm f/4.0L USM is the only I own. The main reason is that zooms give you far more bulk and worse image quality at the same time, compared to primes. I'm a lazy person, actually most people are, and when I use zoom lens I usually just zoom and click, so get a snapshot instead of photograph. A prime makes me think and compose carefully using my feet. But with wide angle it may be difficult to compose with feet, so wide angle zoom is a reasonable compromise for me.

A new and affordable L-series ultra-wide-angle zoom lens that's ideal for both film and digital SLRs. Superior optics are assured by the use of three aspherical lens elements, in addition to a Super UD (Ultra-low Dispersion) glass element. Optical coatings are optimized for use with digital cameras. This lens focuses as close as 11 inches (0.28m), and offers both Canon's full-time manual focus and. It has a constant f/4 maximum aperture, and offers the choice of screw-in 77mm filters or a holder in the rear of the lens for up to three gel filters. Finally, it offers weather-resistant construction similar to other high-end L-series lenses – this is a short description from official Canon web site.

If you need an ultra wide angle zoom for full frame camera, or a general purpose lens for APS-C camera Canon EF 17-40mm f/4.0 L USM can be a good choice. This review covers usage of the lens with APC-C or so called crop bodies, like Digital Rebels/xxxD series and xxD series cameras. Actually, Canon EF 17-40mm f/4.0L USM really shines on full frame bodies, where it is used as descend UWA lens as intended. I own this lens since 2004, and it never disappointed me.  Almost every photographer, who started with APS-C digital EOS camera, starts with 18-55 kit lens, It’s a nice value for a beginner and is good for learning and understanding what you really need.  As your photographic skills grow up, you start to think about better quality general purpose lens.

Canon EF 17-40mm f/4.0 L USM is the lightest Canon L zoom lens in terms of weight. As most L lenses it is build to last. Both zoom and focus rings are in a right position and operate smoothly, of cause without any creeks or wobble. The lens is equipped with a powerful ring-type USM for fast and silent AF operation, and allows full time manual override. AF speed is one of the best in class, it focuses nearly instantly even on an ancient Digital Rebel/300D body, not to mention something newer and more capable. AF accuracy is also very good. I never experienced a single problem with AF with this lens.
The lens is focusing internally and doesn’t change its size while zooming. Filter thread is fixed and doesn’t rotate, so it accepts polarizing and gradient filters well.

Canon EF 17-40mm f/4.0 L USM mounted on Canon 7D in snow.


Canon claims that the lens is weather sealed. I can confirm that its construction is rugged enough to withstand sand and dust of India and Egypt, and moist and rainy climate of Vietnam and Cambodia. In 5 years I’ve exposed it to various rough conditions but it always performed well. Now with the 7D weather sealed body I never hesitate to use the combo even in heavy snow. I must remind you, that in order to be fully environmentally sealed Canon EF 17-40mm f/4.0 L USM lens must be equipped with filter. I recommend using high quality UV or protection filter, that doesn't degrade image quality, to protect the front element from accidential fingerprints, dust, waterdrips and scratches. Good examples are Canon Protect filter, or B+W UV MRC filter. B+W UV MRC filters are probably the best, as they don't degrade image quality at all, and cleans very easily, thanks to special coating. The bayonet mount is protected with rubber seal. I feel much more comfortable cleaning dust and fingerprints from filter than from an expensive lens, sure one shouldn't expose lens to this, but unfortunately it happens sometimes.

Optically Canon EF 17-40mm f/4.0L USM is very little to complain, unless you want to pixel-peep borders of something shot wide open at 40mm.    It is reasonably sharp wide open and very sharp stopped down. The lens is sharper towards wide end of the zoom range. At apertures from f/6.3 to f/16 which is a common setting for landscape photography, there is absolutely nothing to complain. Color reproduction is very accurate; saturation and contrast are excellent, what is common for Canon L glass. It captures almost all fine details, look at the subtle green tone gradations in the grass on Slovakia rural shot or bricks in Stockholm panorama!

Stockholm panoramaStockholm panorama from city hall. Canon 40D, 40mm, ISO 100, 1/200s, f/8.


100% Crop from Stockholm panorama.

SlovakiaSlovakia rural landscape with bicyclist. Canon 40D, 26mm, ISO 100, 1/200s, f/8.

Grass details from Slovakia rural road shot, 100% crop.


Chromatic aberration on Canon EF 17-40mm f/4.0L USM may be noticeable in extreme conditions, but in real life shots there is nothing to worry about, on the sample shot you can see blue color cast to the left and red color cast to the right. Anyway they can be corrected very easy with appropriate software, especially with new versions of  DPP, which knows every Canon lens, and corrects CA without any noticeable degradation of image quality, actually corrected images appear  even a bit sharper than unprocessed ones. You can see the corrected and original versions on the crops left one is original, right processed:

Chromatic Aberration sample, 100% crop.

Notre Damm de Paris. Canon 40D, f/8, natural light.

Uxmal, Mexico, Governors palace, Canon 40D, f/8, natural light.




Vignetting is not field relevant on APS-C bodies with Canon EF 17-40mm f/4.0L USM. I never noticed it on any of my shots. Even with standard thickness filter attached there is nothing to worry about.
Distortion may be noticeable in some shots only near wide  end of zoom range, but it can be corrected relatively easy in software. At 24mm or 40mm its negligible in real life use.

Bokeh, or how the lens renders of out of focus areas, is a very important characteristic of any lens. Canon EF 17-40mm f/4.0L USM  bokeh is quite good, thanks to 7-blade circular aperture, but to get a shot with separated and blurred background you should have your subject very close to you. Inability to isolate subject from the background is the only thing that I really hate about this lens. Landscape shots usually have everything in focus, so not many people care about bokeh here.

Canon EF 17-40mm f/4.0L USM lens ships with a petal type EW-83E lens hood and LP1319 soft lens pouch. Hood is ridiculously large and makes storage and transportation cumbersome. So I usually leave it at home, as I like travelling light and there is not enough space in my backpack to carry the hood which I probably won’t use. I’ve not noticed any difference in image quality with and without hood. Canon EF 17-40mm f/4.0L lens resists flare quite good, I have very few shots where it is an issue. Here is an example:

Flare sample, Wind blows sand over deserted beach in Porto. Canon 40D, 17mm, 1/1000s, f/8

Canon EF 17-40mm f/4.0L USM  can be used in a variety of photographic scenarios. Most obvious use for it is landscape photography.  Canon EF 17-40mm f/4.0L USM really shines here as it is sharp, has low distortion and produces richly saturated images with good contrast.

It may be used as a general purpose lens, I usually take it with me when I travel.
You should avoid using Canon EF 17-40mm f/4.0L USM for portraits, I mean head and shoulders portraits or head shots. With such short focal length features of the face of you subject will be exaggerated probably more than you subject wants to see. It is good for full body and environmental portraits, when you want your subject to be a part of a beautiful landscape. Canon EF 17-40mm f/4.0L USM is a very nice wildelife lens, and I'm not joking here. If you manage to get close enough, the results will be even better than those from big white telephotos, just look at the squirrel below :)

Squirrel eating nut. Canon 7D, 22mm, ISO 1600, f/5, 1/250s.

There some alternative lens on the market, but I must conclude that Canon EF 17-40mm f/4.0L USM  is a very good all round performer without any significant weakness in any area. Canon EF 16-35mm f/2.8L II USM is better, but it costs about twice as much. Two lenses mentioned above can be used as a very good UWA lens on full frame cameras. None of these lens has IS, but I've never wanted one for a wide lens. Canon EF-S 17-55 f/2.8 IS USM is very good optically, it is faster and has more reach, but it costs more, weights more and is not rugged and environment sealed. Canon EF-S 17-85mm f/4-5.6 IS USM is simply bad optically,  it is just a tiny bit better than 18-55 kit lens, but costs a lot, so despite the good focal length range I never recommend it. New Canon EF-S 15-85mm f/3.5-5.6 IS USM seems to be much better, but not without drawbacks and I have not used it myself, so I cannot compare it with Canon EF 17-40mm f/4.0L USM yet. If your budget is limited, Tamron 17-50mm f/2.8 XR Di II is worth considering, it is sharp, relatively compact, and has constant f/2.8 aperture, but it is not weather sealed like Canon EF 17-40mm f/4.0L USM. Tamron 17-50mm f/2.8 Di II VC is just announced, so we will see how it performs later.


There are many shots with this lens in my gallery:

Slovakia, Spain, Portugal, Austria, Mexico, France and more...

You can buy Canon EF 17-40mm f/4.0L USM here (use these links to support this site) :

Canon EF 17-40mm f/4L USM UWA Zoom Lens at

Canon EF 17-40mm f/4L USM UWA Zoom Lens at Adorama

Canon EF 17-40mm f/4L USM UWA Zoom Lens at B&H Photo

Rebates awailable for this lens!

You can read some Canon EF 17-40mm f/4.0L USM reviews here:

Thanks for reading!


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