I spent some time shooting with Canon's 17-40 4.0 lens last night. There are a lot of things to like about this lens. At 17mm, the lens offers a dramatic perspective as shot above illustrates. It's also very light, produces some very sharp images, and is fairly inexpensive. An obvious drawback is the narrow apature and for night photography a tripod is generally necessary. That said, I shot the above photo handheld at 1/40 seconds and an ISO of 3200.