The Zeikos 52/58mm High Quality 0.18x Super Fisheye Lens is an auxiliary lens that attaches to the front of an existing lens with a 58mm filter thread. For lenses with a 52mm thread a step-up ring is included. This auxiliary lens, when added to the front of your camera's lens, will create a circular image which will be 0.18x wider than your existing lens. This fisheye lens is made with multicoated optical glass, and has a steel barrel. Using this "auxiliary" fisheye lens is an economical alternative to buying expensive wide-angle lenses.