Here is the workhorse L-series (top of the line) Canon EF lens. The only problem is that the autofocus works intermittently, so manual focus is your best option. Price reflects this. IS (Image Stabilization) means that the image will remain steady and sharp even at slower shutter speeds (within reason) and also when hand-holding DSLR video. A must-have lens for serious Canon photographers and videographers. $350 is firm.