The Canon EF-S 17-55mm f/2.8 IS USM Lens, with a fast, fixed f/2.8 aperture, very high image quality, 3-stop Image Stabilization and a very popular focal length range, is one of the best general purpose lenses available.
Since EF-S lenses only mount on Canon EF-S bodies - which all feature a 1.6x FOVCF - the 17-55mm focal length range always equates to the field of view of a 27.2-88mm lens mounted on a full-frame Digital SLR. This range covers what I consider to be the most important focal lengths for a Canon general purpose lens. This is a focal length range that can be used for everything from a wide scenic landscape to a relatively-close portrait.
Canon already had these focal lengths similarly covered in their econo kit lens - the Canon EF-S 18-55mm f/3.5-5.6 Lens. Reality is that these are vastly different lenses - in build, optical and feature qualities - and price. The kit lens is a good value for the money, but does not compare with the 17-55 IS.
Canon already had a superset of the 17-55mm focal length range covered with the Canon EF-S 17-85mm f/4-5.6 IS USM Lens. The EF-S 17-85 IS has a higher build quality, image quality and feature set than the EF-S 18-55 - adding Ring USM and 3 stop image stabilization to the feature set. What the 17-55 IS adds to the 17-85's feature set is a fixed f/2.8 aperture and L-Series grade UD (Ultra-Low Dispersion glass) lens elements. Of course, price, size, weight and a reduced focal length range are the downsides of the 17-55 compared to the 17-85.
Positioned above from left to right in their fully retracted positions are the following lenses:
Canon EF-S 18-55mm f/3.5-5.6 IS II Lens
Canon EF-S 15-85mm f/3.5-5.6 IS USM Lens
Canon EF-S 10-22mm f/3.5-4.5 USM Lens
Canon EF-S 18-135mm f/3.5-5.6 IS Lens
Canon EF-S 18-200mm f/3.5-5.6 IS Lens
Canon EF-S 55-250mm f/4-5.6 IS Lens
Canon EF-S 17-55mm f/2.8 IS USM Lens
The same lenses are shown below in their fully extended states with their lens hoods in place.
With a fixed fast f/2.8 aperture (meaning the widest aperture opening is f/2.8 through the entire focal length range - f/22 is the narrowest setting), exposure settings do not change when zooming in on a subject. To some, this is not a big deal - to me, this is a great feature. F/2.8 is as fast as any Canon zoom lens currently made. It is fast enough to stop action in many indoor venues (higher ISO settings typically required - fast action indoor sports may require f/2 or wider). This wide aperture also activates the higher autofocus sensitivity mode for certain focus points in many Canon bodies (f/2.8 does not have to be selected to get the benefit of this feature). F/2.8 also presents a bright viewfinder to the user.
Wide open, the 17-55 is able to produce a nicely blurred background. By employing a circular 7-blade aperture barrel, the Canon 17-55mm Lens produces a decent quality background blur even when stopped down. With a focal length range that is composed of relatively wide focal lengths, this lens needs a close subject to create a diffusely blurred background.
Combining an f/2.8 aperture with the 3 stop image stabilization, the Canon EF-S 17-55mm f/2.8 IS USM Lens is arguably the most handholdable lens Canon currently makes. Image stabilization will allow a shot to be taken at a shutter speed up to 3 stops slower than without IS. Sorry, but IS will not stop subject motion. This IS version is tripod sensing to prevent feedback loops between the IS sensor and stabilizer motor vibrations. The manual recommends turning IS off when tripod-mounting the lens (to save battery life) or when panning (panning mode IS is not available). Leave IS on when handholding or shooting from a monopod. The IS implementation on this lens is very well behaved - it is quiet and does not cause the image to jump when starting up.
The three lenses compared above are from left to right, the Canon EF-S 17-55mm f/2.8 IS USM Lens, Canon EF-S 17-85mm f/4-5.6 IS USM Lens and Canon EF-S 18-55mm f/3.5-5.6 IS Lens. All lenses are shown extended to their maximum lengths with their optional lens hoods attached.
With Ring USM (Ultrasonic Motor), the 17-55 IS focuses very quietly and very fast. Focus accuracy has been very good for me (an equally or even more important fact). FTM (Full Time Manual) focusing is a very nice feature of this lens. The focus ring is rather small, but turns easily. Likely to get far more use is the zoom ring - it is very nicely sized and turns smoothly with little effort. The AF and IS switches are recessed to prevent accidental changes.
Canon claims that "By optimising Super Spectra lens coatings and lens element shaping, Canon’s engineers have been effective in suppressing flare and ghosting more prone to occur with digital cameras due to reflection off the image sensor. By increasing light absorption, coatings reduce reflections off lens element surfaces to deliver crisp, undistorted images with natural colour balance." In reality, I am finding the 17-55 IS to be quite flare-prone if the sun or bright light is in the frame. Otherwise, color and contrast are excellent.
Prior to receiving my 17-55 IS, I stated that I expected its image quality to match or nearly match that of Canon's L Series Lenses as it shares the L-Series UD lens elements. As it turns out, my 17-55 matches or exceeds the optical performance of my L-Series zooms in this similar focal length range ...
This lens is sharp! Wide open and from edge to edge. Unless the distance is close that is - I'm finding that close subjects do not produce the same image sharpness as normal distance subjects. The ISO 12233 chart test results indicate this as well. The 17-55 IS shows slight sharpness improvement at f/4, but performance at f/2.8 is very good.
My Canon EF 16-35mm f/2.8 L USM Lens is slightly sharper in the center at 17mm wide open, but the 17-55 IS is sharper at all other tested focal lengths - and proved much sharper in the corners at all focal lengths and apertures. Distortion was also less on the 17-55. In my opinion, the only reasons to buy the 16-35 over the 17-55 are for full-frame compatibility (a big reason), better build quality and environmental sealing (EF-S compatible bodies are not weather sealed at this time).
Similar story with the Canon EF 17-40mm f/4 L USM Lens. The 17-55 IS is sharper at all other tested focal lengths - and proved much sharper in the corners at all focal lengths and apertures. At close distances, the 17-40 had sharper corners and held its sharpness to a narrower focal length than the 17-55. Lower barrel distortion at the wide end is also in the 17-55's favor. Full-frame compatibility, better build quality and environmental sealing are in the 17-40 L's favor. I suspect the wider price discrepancy between these two lenses will keep sales of the 17-40 L going stronger than for the 16-35.
The Canon EF-S 17-85mm f/4-5.6 IS USM Lens boasts a longer focal length range but lacks the fast aperture and is not as sharp (especially in the corners) as the 17-55 IS. The two lenses are rather close in center sharpness but most of the time my primary subject is not dead center in the frame. Once again, lower barrel distortion at the wide end is in the 17-55's favor. Price is also a differentiator between these lenses.
The similarly-built Canon EF-S 10-22mm f/3.5-4.5 USM Lens turned in similar optical results to the 17-55 IS in the short range of focal lengths that overlap. I see these lenses more as complementary than competing.
At all overlapping focal lengths and apertures, the 17-55 is sharper than my Canon EF 24-70mm f/2.8 L USM Lens.
The default image below is a 100% crop from the 17-55 IS at 55mm, f/2.8. Mousing over the image will show a crop from the Canon EF-S 18-55mm f/3.5-5.6 IS Lens at f/5.6 (wide open). Keep in mind that the 18-55 IS should have a DOF advantage, but you will see the 17-55 IS still performing better in the foreground and background. Also, the vehicle grill is the center of the frame - where the 18-55 IS competes best. However, this focal length is the weakest in the 18-55 IS's range.
Some additional information about the above comparison ... This comparison was shot with a Canon EOS 40D. There was a 250-pixel-wide swath removed from the image as indicated by the white line. This allows a foreground object and some background to be present in the image to confirm focus accuracy.
Images were shot as RAW and processed with the Neutral Picture Style (0 Contrast) and sharpening = 1 (very low - 2 would look noticeably sharper). Images were converted in DPP to 16-bit TIFF files, cropped in Photoshop and saved as 80 quality JPG files. The lighting was harsh mid-day sunlight on a clear day. A tripod was used - the shutter speed was 1/2000 for the f/2.8 shot 1/500 for the f/5.6 shot.
In addition to being sharp, CA (Chromatic Aberrations) are very well controlled in the 17-55 IS. The following example is meant to show the difference in CA between an economy lens (18-55 IS again) and a top quality zoom. This one was shot at 17mm/18mm and at f/5.6 for both lenses. This 100% crop sample is located about 25% into the frame from the top left corner. Mousing over the image will show the 17-55mm IS advantage.
Distortion is present over most of the 17-55mm focal length range. Mild barrel distortion is present until about 24mm where pincushion distortion becomes present through 55mm. Your spouse will appreciate how the 17-55 makes them look thinner at the longer focal lengths (use this excuse if you need help getting spousal purchase permission).
Being a wide aperture, wide angle lens, expect to see some vignetting from the 17-55 IS. The amount of vignetting is less than I anticipated - basically visible only in the corners at f/2.8 when photographing an even-colored subject such as a blue sky. One of the benefits of using an EF lens on a 1.6x body is that much of the lens vignetting is not apparent within the cropped field of view.
The 17-55 passes distance information to the camera body for use in E-TTL II exposure determination. Most new Canon lenses have included this feature.
The Canon EF-S 17-55mm f/2.8 IS USM Lens is a middle weight at 22.8 oz (645g). At 3.3" x 4.4" (83.5mm x 110.6mm), the 17-55mm IS becomes the largest EF-S lens to date. It is, however, a very nice size/weight to carry around and balances well on compatible camera bodies.
To put size into perspective, the above size comparison photo includes from left to right the Canon EF 17-40mm f/4 L USM Lens, Canon EF 24-105mm f/4 L IS USM Lens, Canon EF-S 17-55mm f/2.8 IS USM Lens and Canon EF 24-70mm f/2.8 L USM Lens. The same lenses are show fully extended below.
Similar to many of the L-Series zooms, the 17-55 IS features a 77mm filter thread. A feature appreciated by circular polarizer filter users is the non-rotating front element (does not rotate with focusing or focal length change). The 17-55 extends with focal length increase, but does not extend with focusing.
With a relatively-long-for-its-focal-length-range closest focusing distance of 1.15' (0.35m), the 17-55 IS yields a meager maximum magnification of 0.17x (at 55mm). As usual, extension tubes can increase the magnification ability significantly. With the Canon EF 12mm Extension Tube II, magnification is 0.45x-0.231x. With the Canon EF 25mm Extension Tube II, magnification is 1.71x-0.51x (Canon's spec). As this is an EF-S lens, version II of Canon's Extension Tubes are required. The 17-55 is not compatible with Canon's Extenders.
The 17-55 IS shares design and build qualities with Canon's other recently-released EF-S Lenses - especially the Canon EF-S 10-22mm f/3.5-4.5 USM Lens. It is nicely designed and well thought out, though I don't prefer the rear-positioning of the manual focus ring (that is where I generally grip the lens). The 17-55 IS is not as elegant in design and function as the L-Series zooms, but it is very good in this regard. Not real important but missing is the Canon date code.
I'm not sure why Canon did not go all the way and make the 17-55 IS an L-Series lens. An upgraded (metal) lens barrel seems to be the missing component - and the red ring. Also, the accessories included with L-Series lenses are missing - the Lens Pouch LP1219 and 17-55 IS-exclusive Lens Hood EW-83J are optional. Since Canon has an L-Series lens on the PowerShot Pro 1, making a non-"EF" L lens is apparently not outside of their definition. This lens certainly has the image quality to be an "L".
With the help of a 12mm Extension Tube, you can physically mount this lens on a full frame body. But you probably will not want to. The image above shows the image circle as seen through this combination by a Canon EOS 1Ds Mark III. In addition to the heavy vignetting, AF does not work and the aperture information does not report to the camera. Even in MF mode, more hurdles remain - at 55mm, the 17-55 will not focus any farther away than about 7" or so in front of the lens. This distance rapidly decreases as the focal length is widened until the subject is against the glass and beyond this point no subject can be in-focus. It was a fun exercise at least - and now we know.
I am getting some email asking about dust issues with this lens. Some are seeing a noticeable amount of dust collect under the front element. Dust seldom makes a noticeable difference in image quality - No one has indicated to me that their dust has affected the image quality of their 17-55. But it is not normal for this amount of dust to accumulate inside the lens. My 17-55 came with one small speck of dust in it (a genuine Canon factory dust speck I suppose) and has not accumulated any additional dust. I've shot thousands of mostly outdoor pictures with this lens.
Weddings, events, parties, family activities, portraits, landscapes, stage shows, car shows, night sky ... there are far more uses for this lens than I am going to think of. Unless there is an upgrade to a 1.3x or full frame body in your future, the Canon EF-S 17-55mm f/2.8 IS USM Lens is an ideal lens to include in your kit. Even if a larger format sensor body is in your future, the resale value of this lens remains strong.
With the introduction of the 17-55 IS, Canon displays its commitment to the EF-S line of lenses. With the huge base of Canon EF-S Digital SLR users, the 17-55 IS, with its excellent features, specs and image quality, will find a home in many professional and amateur photographers' kits. This is the lens I keep mounted on my 1.6x body (currently a 50D) - I highly recommend it.