I have had this lens for over two years and still can't believe how good the quality is. It's focal range is 17mm to 40mm. It has followed me to all sorts of locations around the world and has produced top rate results in a vast variety of conditions. I use it with a crop frame body for a wide variety of landscapes, people, buildings etc. It is so versatile, I have stopped using some of my other lenses. Coupled with a telephoto lens, I can cover most of my shot requirements. I have not come across any bad points so all good. If you have a Canon SLR camera, buy this lens.