The Opteka 500mm mirror lens is incredibly compact and lightweight (Opteka 500mm with 2X Multiplier). Using an advanced reflex design, this is a mirror lens that is ideally suited for wildlife and sports photography. It has a fixed aperture of f8. It comes complete with a soft pouch and three (3) rear mounted, 30.5mm filters, (ND-2X, ND-4X & Skylight). Opteka mirror lenses incorporates advanced computer designed optics and the latest in multi-coating techniques. The process of multi-coating assures virtually flare free photographs even under adverse lighting conditions resulting in crisp high contrast pictures with full color fidelity.