The Opteka 650-1300mm high definition super telephoto zoom lens is perfect for the professional and amateur photographer alike. There is a built-in, rotating tripod mount for easily attaching to your tripod or monopod. It"s an extremely powerful telephoto zoom lens with the versatility that you need. This lens is great for the wildlife or nature photographer who wants to be hidden while taking photos of the subject. Advances in ultra high-index / low-dispersion optical glasses, new barrel materials, and exotic anti-reflection coatings, along with the latest in computer-aided-design / computer-aided-manufacturing, are combined to produce lenses of unprecedented quality. Diamond-cut from crystal-clear, water-white optical glass, Opteka lenses are ground and polished to a precise precision. Because all Opteka lenses are designed and manufactured with the highest possible degree of consistency, you can swap lenses mid-shoot with no discernable variation in color or effect. The unprecedented purity, color saturation and repeatability of Opteka lenses virtually eliminate the need for lab color timing corrections caused by other filters. This puts more creative control where it belongs, in your hands. The Opteka 2x High Definition Tele-Converter is for use with T-Mount manual focus lenses. It will multiply the focal length of your existing lens by 2x, and will cut back the amount of light by two f/stops. For example, using a 2x tele-converter with a 500mm lens will effectively increase the focal length to 1000mm. A lens set to f/2.8 will now be f/5.6.Convert Lens into a high powered Telescope Fits T-Mount lenses Will Magnify Your Lens 10X its Focal length