Update: This review was written a few years ago when the lens first came out. In the meantime, the lens' high price has fallen by about 25%, reducing one of my main objections that I wrote about. However, there are also more alternatives, such as stabilized hyperzooms (18-200mm and 18-250mm) from various manufacturers like Canon and Tamron. Much of what I said about the lens still applies, but should be taken in the context if these newer developments.
Thanks, and now back to the original review:
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The main feeling this lens gave me was indignation ... mainly at having to pay professional-level prices for amateur-grade optics. If you really need the image stabilization this is a decent choice, but if you don't (and it might be less useful thank you think), it is likely that you can get another lens (or two) with the same money that meets your needs better. This lens costs more than some "L" lenses, yet has as much chromatic aberration and almost as much purple fringing as the dirt-cheap 18-55 kit lens. In a cheaper lens, these defects would be acceptable, but at $599, I find them hard to justify. This is not a bad lens, but I didn't love it enough to part with that much money. This lens is even costlier than the older 28-135 IS lens on which it is based. Weren't EF-S lenses supposed to be cheaper (because they're smaller and have less glass) than full-frame?
Before I tried it, I thought I would love this lens due to its 5x zoom range, USM focus, and phenomenally good image-stabilization. However, in the end I did not keep this lens, and used the money to get something else. With my shooting habits, this lens fell short of my needs in many ways:
1. IS wasn't as useful as expected. I really enjoy IS in the 100-400L, but the 17-85 range was short enough that even on cloudy days, I didn't usually need IS. I thought I would use it mostly indoors, but in reality I found myself avoiding it because my indoor shots usually included people and/or pets, not stationary objects. (How often do you photograph the furniture?) Whereas IS reduces the effects of camera shake, it can enhance blur from subject movement because it tempts you into using slower shutter speeds. At $599, the IS wasn't earning its keep. For indoor low-light shooting, I got a fast prime instead: the Canon 35mm f/2, which was cheap ($220), small, and much better for photos of people who aren't sitting still. Considering how often I use that little lens, it was a bargain compared to the 17-85. I know some people will fault me for comparing a prime to a zoom lens (apples vs. oranges) but in the end, money is money, and you should spend it only on lenses that do what you need.
2. When I want to zoom, I want to REALLY zoom, e.g. to capture animals and people at great distances. I had hoped to extend the Canon's range with a teleconverter. Although attaching teleconverters to zoom lenses is usually not recommended, I had hoped the IS would help this lens to at least function adequately. Unfortunately, it turns out you can't physically attach a teleconverter to this lens because of the EF-S mount, which is incompatible with any teleconverter I know of (this includes Canon, Tamron, Sigma, and Kenko brands).
3. Optically, this lens has more aberrations than I would like to see for this price. Surprisingly, its chromatic aberration is slightly WORSE than the cheap kit lens. It's even worse than the Sigma 18-125 and 18-200 mega-zoom lenses. Also, purple fringing is worse than with the Sigma lenses, particularly at the Canon's max zoom (85mm), where it is very noticeable around bright objects. These aberrations are bad enough in a cheap consumer-grade lens, but as I've mentioned ad nauseum, this lens is darn expensive, and its cost is in the range of many professional "L" lenses. Canon's legendary 17-40L only costs $80 more than the 17-85, and the stupendous 70-200 f/4L costs $20 less! (B&H prices as of 7/4/2005).
4. The main attraction of the 17-85 is convenience, combining low-light capability with telephoto and wide angle reach. But even as a convenience lens, I wasn't sold. The 17-85 is supposed to minimize lens-changing, but I found myself changing lenses quite frequently to get more telephoto outdoors, or larger apertures indoors. I found myself bringing along an extra 2nd or 3rd lens despite having the 17-85.
5. $599 is enough to get 1 or 2 other lenses, so unless you consider this pocket change, or find an unusually good deal, you should check whether this is the best use of your money. For about $50 less, I bought a Sigma 18-200 AND a Canon 35mm f/2, giving me much more range and aperture. Of course, neither has IS, but as I already mentioned, I found IS to be less useful than large apertures at these focal lengths. And while my copy of the Sigma lens doesn't focus properly near 200mm (see my review of that lens here:
http://www.epinions.com/content_185158569604), it's fine elsewhere, and hence still gives me more reach than the 17-85.
Ultimately I thought the 17-85 was a nice enough lens, but for my limited budget, there were better options.
