After a long decision-making stage, I have between the 16-35mm 1: 4L ruled in favor of the 16-35mm II: 2.8L II and 17-40mm 1. I on the 5D Mk III using the lens, has put me off at 17-40mm of sudden sharpness drop in the corners up to total blur. This is not observed with the 16-35mm II. Overall, it makes a direct comparison at maximum aperture the sharper and clearer images with less CA. The sharpness in the corners is perfectly aperture 8, in the center already from open aperture super. The ultrasonic drive is beyond doubt and harmonizes III reliably and quickly with the Auto Focus 5D Mk. For me, the purchase was worth.
