Canon EF 17-40 f/4 L Lens Review

Canon EF 17-40 f/4 L with Hood

For a very long time, this was my only wide lens. The vast majority of what I shoot falls in the standard to telephoto range, and until I bought this lens, I was really not much of a fan of wide lenses. In fact, before I purchased this lens, my widest focal length was 24mm. In 2003, though, I decided to shoot more landscape and outdoor event photography, and so I started to look at this lens and its sibling the Canon 16-35 f/2.8 L (which has been subsequently updated and re-released in a Mk II version).

Fortunately, my local pro camera store let me test both lenses against each other, and I spent the better part of a morning shooting with both the 17-40 and the 16-35 on my 1.6 crop camera body. I was able to subsequently download the images from my CF card to my computer where I could do some detailed comparisons. What I found was that the 17-40 had better flare control, saturation and corner sharpness than the 16-35 f/2.8 L and even though it was a full stop slower, the 17-40 f/4 L was a better lens for the money. At nearly half the price of the f/2.8 lens, it certainly fit into my budget better.

Canon has noted the failings of the 16-35 f/2.8 L and in April 2007 they released an updated version (MK II) of this lens which corrected for the corner sharpness and flare issues, though at an increased price and with a larger filter size.

This was one of the first Canon lenses designed for use with the consideration of consumer digital cameras. The lens was designed as a high-end version of the EF 20-35 f/3.5-4.5 USM lens, and featured a new optical system design to provide the expanded zoom range. Featuring 12 lens elements in 9 groups, the lens utilizes three aspherical elements (one high-precision molded element and two replica aspherical elements) as well as a Super UD (ultra-low dispersion) glass element. The aspherical elements provide the extended zoom range with minimal aberrations, while the Super UD element, according to Canon, "minimizes the chromatic aberration of magnification that tends to occur with wide-angle lenses, eliminating color bleed along the edges of the subject and realizing high image contrast and resolution." As far as I can tell, Canon's claims are quite accurate.

Portrait at 40mm and f/4

Weighing in at only 1.05 pounds (475 grams), this is one of the lightest L lenses available (and that includes some of the L primes). This makes it a real joy to use when hiking or backpacking. Because of its light weight, moderate price, and build quality, this is actually one of Canon's best selling lenses.

The zoom ring is smooth and well damped. The hood mounts on a non-extending portion of the lens barrel and the petal shape ensures there is no vignetting at the wide end of the zoom range. The focus ring is also wide and well damped, and the focus moves smoothly and easily across the range. The 7 bladed aperture provides a nice, round aperture and improved background blur when compared to its predecessor, but unless you're close to your subject and shooting at the long end of the zoom, don't expect to get much background blur from the wide angle, f/4 lens.

An interesting feature of this lens is a rear filter slot which allows the use of up to three thin, cut-to-size gelatin filters. I've never used this feature, but I could see where it could be useful for stacking ND filters to get a slow shutter speed in bright lighting conditions.

As expected of a Canon L lens, the build quality is excellent. The lens uses Ring type USM auto focus which allows Full Time Manual focus override. Minimum focusing distance is 11 inches (0.28 meters ) and the lens utilizes an internal focusing system with a non-rotating front element. This is great when shooting with a circular polarizing filter. Like the 16-35 f/2.8 L Mk II, this lens is dust and water resistant (weather sealed). Be aware that a filter is necessary to complete the weather sealing. The front element moves only slightly when zooming, that is to say, this is a non-extending zoom.

The provided EW-83E hood fits snugly via a bayonet style mount and is flocked on the interior to absorb light. The hood is made out of high impact plastic and is very easy to mount. I reverse mount my hood on the lens for easy storage. Filter size on this lens is 77mm making it easy to share filters with the other L zooms such as the 70-200 f/2.8 L IS, the 24-105 f/4 L and the 24-70 f/2.8 L.

This lens is quite sharp though out its range, and the sweet spot for sharpness occurs at about f/5.6. The lens boasts excellent flare resistance, which is quite surprising given how wide the lens will zoom. There is minimal light fall-off when used on a 1.6 crop body, and only moderate light fall-off on a full frame camera. Color and contrast on my copy of this lens are excellent. Some reviews report moderately strong barrel distortion at 17mm and mild pin cushion distortion at 40mm. Since I seldom shoot brick walls at short distances, I've never noticed this as a problem.

Although best suited as a landscape lens, the 17-40 f/4 L can be used to effectively shoot portraits on a 1.6 crop camera. I've often used it for fair and festival photography to capture the overall feel of an event. Many people use the 17-40 as a walk around lens on a 1.6 crop camera, but I prefer a longer focal length for my style of photography. Still, if you're a fan of wider shoots, this lens would make a fine lens for general outdoor photography.

Technical Details for this Lens

Additional Images

Underneath the Columbia River Scenic Highway	Multnomah Falls
Open Shade Portrait	Hawaiian Lava Tube
Latourelle Falls, Columbia River Gorge
Scenic Bridge, Columbia River Gorge
Hawaiian Landscape - f/18, 1//250th, Canon 1DMKIIN
Ferns in Volcano National Park, Kahauale'a Rim - 1/320, f/5 @ 17mm on Canon 20D
Wamea Canyon, Kauai - 1/320, f/8/ @ 17mm on a Canon 1DMKIIN
Wamea Portrait - 1/320, f/8/ @ 17mm on a Canon 1DMKIIN