Excellent Lens

After switching from film to digital, I realized just how much the 1.6x crop factor of the new camera limited my wide-end abilities. I wanted that extra "wow" factor back, and this lens definitely delivers.

Weight: The first time I took it out of the box, I was impressed with its size versus weight. This lens is light, weighing in at almost 100 grams less than sigma's 10-20mm (385g vs. 470g) but not as light as Tamron's 11-18mm (355g). This makes it easier to haul the lens around for quite a while.

Construction: The lens is mostly plastic except for the metal lens mount, but it feels solid. The one problem I do have with its construction is the fact that the filter threads are also plastic. Not fragile, but it won't take much force to cross-thread them. Having said that, You can see from a profile shot of this lens that the filter threads are enlarged to eliminate vignetting--a common problem with lenses this wide. You won't see any vignetting at all with this lens until you either put two standard filters on it or you use a standard circular polarizer; I recommend purchasing a "slim" circular polarizer, otherwise you're left with the options of having to crop your shots, or not fully using the wide end which is most likely why you want the lens in the first place. Vignetting with a standard C-PL will disappear, however, at about 11 or 12mm.

Focusing: Canon's USM technology provides laser-sharp focusing at lightning-quick speeds, and this lens is no exception. The only sound you'll hear is the parts sliding against each other, but no gearings or motors. Also included is a distance scale, measured in feet and meters, that is convenient for night shooting. And since the lens employs inner focusing, the front element does not rotate, meaning you don't have to adjust your polarizer after each time you focus. Full-time manual focus is very convenient and the minimum focusing distance of 9.5 inches is great for moving in close.

Zoom: Smooth, fluid movement. The lens length does not change during zooming, and the focal distance is not affected by focal length meaning you can zoom from 10 to 22mm and not need to adjust your focus.

Clarity: After test shooting with this lens I have to say that the spherical aberration is next to negligible compared to other lens in this category. I have printed 11"x14"'s that were sharp from edge to edge.

The glass quality overall is not like Canon's "L" lenses, but I'd say best in class. Not as soft as I expected at 10mm, and sharp at 22mm. This lens employs three aspherical elements to reduce barrel distortion, and by reduce I mean eliminate. You can put the horizon at the top of the frame, and it's perfectly parallel. Don't confuse this with wide-angle distortion; you'll still get dramatic perspective effects with this lens. A special coated glass element is also used to reduce flare from spotlights in the frame, and as long as your glass is clean you probably won't see much flare.

Aperture: The Canon 10-22mm lens has a range of f3.5-22@10mm and f4.5-29@22mm, and the aperture blades feature a circular design that will give you smooth, blended out of focus backgrounds.

Overall, I have had a blast with this lens and I feel my money is well spent. Now that Sigma, Tamron, and Tokina wide lenses are on the market, this one can be found at less expensive prices than when it was new. Part of the price is in Canon's name, but I have always felt their glass is worth it.

Be careful when you buy it--this is not a good "walkaround" lens! It's so much fun to shoot with such a wide lens, though, it'll make you forget your other ones.