The Nikon TC-20E III 2x Teleconverter is an exceptional teleconverter optimized for use with FX and DX digital SLR cameras. It doubles the focal length of compatible Nikkor lenses. The TC-20E III is constructed of 7 elements in 5 groups and with Nikon\'s Integrated Coating (IC) you will see improved color and reduced flair. It has one aspherical lens element which virtually eliminates lens aberrations.\r\n\r\nThe 2x extender (also known as a teleconverter) will double the focal length of your existing lens, and will cut back the amount of light by 2 f/stops. For example, using this teleconverter with a 300mm lens will effectively increase the focal length to 600mm. A lens set to f/2.8 will now be f/5.6. Teleconverters are best used with longer telephoto lenses and are not recommended for lenses wider than 50mm, e.g. 28-105mm (35mm format).\r\n\r\nEnhanced Telephoto Versatility\r\n\r\nAn affordable and portable gateway to extend telephoto reach which is ideal for sports, wildlife, surveillance and more.\r\n\r\n2x Optical Conversion Factor\r\n\r\nThe TC-20E III doubles the focal length of select compatible Nikkor lenses.\r\n\r\nAspherical Lens Element\r\n\r\nThe aspherical lens element eliminates coma and other aberrations especially at wide apertures.\r\n\r\nNikon Integrated Coating (IC)\r\n\r\nThe Nikon Integrated Coating (IC) enhances light transmission efficiency, improves color consistency and reduces flare.\r\n\r\nAdvanced Optical Design\r\n\r\nThis teleconverter is constructed with 7 elements in 5 groups and is optimized for use with FX and DX digital SLRs, engineered to meet the needs of professional photographers.\r\n\r\nUsable Lenses\r\n\r\nThe following lenses may be used with the Nikon TC-20E III, some with noted functional limitations. NIKKOR lenses not listed cannot be used with the TC-20E III. The rear elements of NIKKOR lenses not listed can contact and damage the Teleconverter element and must not be attached! List includes current lenses along with l