The canon ef 8-15mm f/4l fisheye usm zoom lens replaces a fisheye lens with a fixed focal length: the canon ef 15mm f/2.8. the canon 8-15 mm is a unique lens, because it is a fisheye zoom lens with a focal length range of 8 to 15 mm, with which you can take both circular and full screen fisheye images.. In august of 2010, canon released the 8-15mm