According to the Tamron 17-50mm review that I read, this lens is classified as a super performance lens. After getting my hands on the lens and after performing some tests myself, I am inclined to agree with the reviewer. Most people who start out with photography use the stock lens that came with the camera, and while it is certainly better than nothing, there is often room for improvement. The problem is that upgrading to a better lens is often a very costly endeavor as people naturally assume they need to buy a lens that is the same make as their camera. Since Canon, Nikkor and the other premium brands put quite a hefty price tag on their products, many people simply stick to their stock lenses. Since Tamron has mounts on their lenses for most of the popular name brand camera bodies, this isn’t an issue and anyone who has yet to try out their products really should give it a try.