Canon EF-S IS USM 17 mm - 85 mm F/4.0-5.6 IS USM Lens

Pros:
5x zoom
Super-fast Ultrasonic Motor
Image Stabilization
Full-time manual focus ability
Circular aperture
Non-rotating front element
Excellent optical quality

Cons:
Size
Weight
Cost
Macro performance

The added telephoto range (5x zoom ratio, 28-135mm equivalent), super-fast Ultrasonic Motor and Image Stabilization were well worth the cost for me. I am constantly shooting in low light conditions, so Image Stabilization has been a lifesaver.

An important note on Image Stabilization: It will significantly improve your hand-held slow shutter shots (i.e. low light) ONLY if the subject is not moving. It lens can't keep your baby from flailing it's arms, but it can keep the image on the image sensor a little more stable and counteract the hand-shake that even the best photographers have.

The lens is large and heavy compared to the standard 18-55mm kit lens, but I prefer its more substantial feel (most of the time) but it will make you camera bag noticeably more snug. If your Camrea is a tight fit with the stock lens, it will probably not fit your bag with this lens - something worth planning for.

The components are all high quality (metal mount, aspheric elements etc.). This is simply a great general purpose with a broad range of abilities.

The one area in which I miss the stock lens is in macro photography, the stock 18-55mm has a very good close-focusing ability of just .9 feet whereas the 17-85mm is at 1.2 feet, with the higher telephoto focal length of 85mm the framing is virtually the same, but I prefer the 18-55mm for macros, it's just good - especially for the price.

The cost is considerable, especially if you are upgrading for the first time, but there are a few things to consider:
1] For $400 (or less), you can extend your camera body’s usefulness considerably. If you have a $1200 30D, that’s a sound investment.
2] If you are replacing a kit lens, they fetch $70-$100 on eBay.
3] If you think you want something that’s full frame compatible (meaning an EF and not a EF-S) for that “some day”, consider that Canon is still producing APS-C (EF-S) sized cameras by the millions, literally. MEANING the resale market will be quite strong for decades to come.

If you're looking for a good Pro-sumer choice, this is it; if you're looking for a professional Lens with awe-inspiring optics, look at spending a grand (or two) more (USD).

The 17-85mm is one of Canon's better general-purpose lens for crop-factor bodies, offering roughly the same field of view as a 28-135mm on a full-frame camera body. The USM focusing is fast and silent. The image stabilizer gains 1-2 stops of shutter speed below the focal reciprocal. The macro range is not a substitute for a true macro lens, but is better than nothing in a pinch. The zoom is reasonably well damped, although it may try to "telescope" whenever zoomed anywhere beyond 17mm. Build quality could be a little better but it's not too shabby at its pricepoint. And finally, the optics: the lens is slightly soft at its base aperture and zoom of f/4 and 17mm, sharpening up considerably by f/5.6. If cost is no object, the newer 15-85mm gets very high marks for image sharpness across the entire aperture range, and also stops down to f/3.5 at 15mm for improved light gathering, but if you're stuck with the 18-55mm kit lens and have a budget that peaks around $300, this is pretty much the ideal intermediate lens.

This lens is a great carry around lens for Canon EOS 20D, 30D, Rebel XT and the other cameras to come that supports EF-S type lens. EF-S type lens only works with the cameras that have 1.6x crop sensor(with EF-S lens support), and the lens won't work with Canon's 5D, 1D series because they got either full frame or 1.3x crop sensor.

There has been other reviews that the lens is somewhat soft, and I agree that it is soft a bit - comparing it to "L" lens or non-zoom lens such as 50mm. But if you need versatility and light weight is what makes this lens so popular among 20D, 30D users. Plus it's got an amazing IS system on board. IS - Image Stabilization WORKS like a charm! If you haven't used one of these IS lens, you should check it out and if you have shaky hands and constantly getting blurred images due to your hand movement, this will definetely give you sharper image.

Many EF-S supporting cameras comes with 18-55mm lens as a kit. 17-85mm seems to focus better and faster. Also, USM (Ultra Sonic Motor) is virtually silent operation when autofocusing.

With 1.6x crop sensor, the lens will perform as 27.2mm-136mm. The image quality, sharpness, colors are very similar to Canon EF 28-135mm lens.

I got this lens after some hesitation, partly because of its supposed "softness" and partly because of the lens working only on the aps-sized sensor cameras. I have been very glad that I decided to get it. The list price _is_ probably too high, but this is eBay, right? While I am amazed that some people will bid lenses and other things higher than mail-order retail prices, I was able to get this lens new from the eBay retail operation of one of the big New York stores for very much less than retail-- so much for its cost. As for softness-well, it produces images on a 20D that are sharper than the 35mm Kodachrome images from my best Nikkors, as digitized at 4000 dpi. It's not a copy lens, but the image stabilization is even better than that on the older IS lenses, and combined with the Canon high ISO abilities, this lens is a treat. By comparison with the little kit lens (18-55mm), it weighs a ton, but the total lens and camera package is well balanced and comfortable to use. Finally, the new 30D Canon shows that Canon is committed to the smaller sensor size for a little while longer, for sure.

LATER - hey, I did get a 5D and a 24-105mm IS L lens, but I still use the 17-85mm IS as my main shooting lens on my two APS-C cameras. I still don't regret buying it -- for one thing, I've had the use of it for a couple of years.

Still later - This lens has been replaced by a new EF-S 15-85mm IS. Many of us who love this lens had hoped for a fantastically improved new one, but it seems to be only somewhat better, and costs almost half again as much. Makes the old one still very attractive used.

I love this lens!!! I have NEVER used or owned any type of camera that had the capablility to accept different lenses. I have always used the instamatics or point and shoot digitals. I love photography and the feel of print pictures. So this review is coming from a COMPLETE amature in every sense of the word. I purchased this particular lens after my husband gave me the Canon Rebel XT for my 40th birthday a few weeks ago. He also booked a trip to China for me and he knows how much I love taking pictures. This lens was the ONLY one that I used for all 1600 photos of my trip and they ALL came out great! During the Peking Opera and Acrabactic shows in a very dark theater I did not use my flash or a tripod ever and every single picture came out crystal clear. I can't say enough about this lens for one thing, I don't know all of the proper photograpic jargon to use. However, this is a nice lens and very light weight. I also like the Macro feature too. I am still playing with it and if a complete novice found pleasure with this little lens I'm sure a more experienced user could really make use of all the bells and whistles featured with this lens. Oh...I almost forgot to mention, I used a polarized UV filter on this lens and the lens cap fits right over it. I read somewhere that you could not use a lens cap and filter together but it worked fine for me. This lens is worth the money and can easily be the ONLY lens that one would use during average photo situations like vacations and family snaps.

Happy IS USM Lens Owner
Barbie