The Canon EF-S 17-85MM f4-5.6 IS USM is the lens that I bought to replace the Sigma 18-125mm F3.5-5.6 DC. It was Canon’s first EF-S zoom lens with IS (image stabilizer).
It was significantly more expensive than the Sigma it replaced. It also has a shorter zoom range at the telephoto end (although it is 1mm wider at the wide-angle end) and has a slightly smaller maximum aperture at the wide end. However, the advantages it has over the Sigma include faster focusing with USM motor, full time manual focus and very useful image stabilizer.
In general, I was very happy with the upgrade to this lens. Focus was fast and accurate. The image stabilizer was extremely useful for shooting under low light. I often was able to shoot at shutter speed as slow as 1/8 seconds consistently. Sometimes, I could even get fairly sharp and usable shots at shutter speed as slow as 1/4 or 1/2 seconds.
The image quality and resolution of this lens is a step above the Sigma. It is still not “L” grade quality though. But again, one wouldn’t expect “L’ grade image quality at this price. My main complaint about image quality of this lens is the severe barrel distortion at the wide angle end. One has to be careful about shooting architectural shots and shots with straight near the edge of the frame. The severe barrel distortion would make these straight lines into noticeable curved lines and could be quite distracting sometimes. Still if you are careful about the kind of subject you shoot at the wide angle end, then the barrel distortion wouldn’t be noticeable.
This lens used to my favorite lens for food photography until I have moved on to using another lens. I also used it a lot for landscape shots until I bought an ultrawide zoom. If you have to use only one lens that is not too expensive on your Canon EF-S mount camera, this would be a good choice though. The zoom range is reasonably versatile. Although, it is a relatively slow lens with smallish maximum aperture, the image stabilizer does at least help with shooting under light low. However, it will not help with freezing action, which a real large aperture lens would help to do.
The following are some sample of shots I have made with this lens.