Canon's EF-S range of lenses is designed to fit only on its crop frame APS-C cameras. The 17-85mm was introduced to provide a APS-C lens that is the equivalent of the manufacturer's very popular 28-135mm EF lens (this lens equates to 27-136mm on full frame cameras). Does this lens live up to its predecessor, though?
Pros
- Good build quality, especially for an EF-S lens
- Accurate autofocus and full manual override
- Ideal lens to keep on the camera as it covers a good focal length range
Cons
- Slow maximum aperture
- Terrible performance at extreme wide-angle
Canon EF-S 17-85mm f4-5.6 IS USM Lens Review
This lens is a big step up in quality from the 18-55mm kit lens that comes with most entry and consumer level Canon DSLRs. It's a particularly useful focal length range, covering both slight wide-angle and telephoto opportunities.
Build Quality
While it's still made of plastic, the 17-85mm is a big step up in quality from the kit lens. The lens mount is made of metal, and it has a proper manual focusing ring. However, like all EF-S lenses, the plastic just doesn't feel as solid as any of Canon's original EF lenses. It's a bit thin and delicate, but it is very lightweight.
Autofocus
This lens benefits from Canon's amazing IS (Image Stabilization), which helps to prevent camera shake. Indeed, it can allow you to hold the camera and shoot without a tripod at shutter speeds three stops lower than usual before any blur from camera shake is visible.
Autofocus itself is fast and pretty silent, and there's full manual override, even when in auto mode. Focusing is accurate, and you'll easily obtain good, sharp results.
Optics
If you shoot at the telephoto end of this lens' range, you'll be delighted with the results. Good quality, crisp images with bright colors are produced.
However, the lens lets itself down at the wider end of its range. If you want to shoot at 17mm -- and you don't want to be tied down to shooting in RAW so that you can make corrections -- this isn't the lens for you!
The biggest problem at 17mm is the highly visible intrusion of green and magenta chromatic aberration. Coupled with some fairly obvious barrel distortion and vignetting at the edges, the lens starts to lose its appeal at this end of the range. (Additionally, once you've taken the crop factor into account, it isn't even that wide-angled!)
In Conclusion
Despite the problems at wide-angle, this is still a decent lens, provided you want to use it at its standard and telephoto range. The accurate autofocus and excellent IS go a long way to making up for its other issues. Just don't buy it if you want to use it extensively as a wide-angle lens.