Canon EF 16-35mm f/2.8L II USM Ultra Wide Angle Zoom Lens

This is Canon's premier wide angle zoom. It has ground aspheric elements, and UD glass for colour correction and less distortion, which can be huge problems on a super wide angle lens. As an L lens, the build quality is superb. It is weather sealed against dust and moisture. Its a bit heavy, but that's good for most lenses. -->means better glass. The focus and zoom ring are nicely damped, and easy to use. This version is designed with digital cameras in mind. The older version had reports of excess blurring because the super wide angle and enormous apertures would apparently bounce some light rays almost parallel to the sensor, which is set farther back than 35mm film. This causes excess unsharpness. This new lens is supposed to help eliminate those problems. They made this new one's front element even wider than before, at 82mm now. This means getting new filters. And quality slim filters at this price range are massively expensive, say $300+ for the B+W Kasemann filter. Be warned. Lastly, it does exhibit some extra barrel distortion, (aside from the typical wide angle) down at 16mm, though as this is almost fisheye territory, that's not a deal breaker. In fact, many of Canon's wider lenses have some problems with this (except the 14mm L). The distortion is easy enough to fix in Photoshop, or any number of aftermarket photo programs. As I lack a full frame sensor, I haven't really noticed this. The distortion is pretty much a non issue until you get a professional camera involved Pros: Sharp through most of the range, good tone, fast autofocus, build quality, IQ etc... Cons: Pricey, although it often qualifies for Canon's biannual mail in rebate. The crop factor on non-full frame cameras leaves it's range less interesting. Perhaps the biggest con is that there is a 17-40mm L f/4 which costs roughly 1/2 the price, but takes (In my opinion) equally good photos, and (in my opinion again) has better colour reproduction. The 16-35 does have the extra stop in the aperture for low light, though. They both have similar distortion but possibly the 16 edges out the 17 for chromatic aberration. Summary: You won't be disappointed!