The PRO 300 can be used with telephoto zoom lenses as well as prime lenses.</br></br>Product Description</br></br>Kenko AF 1.4x Super High Quality Teleplus converter also has genuine Gated Array IC and is compact for light weight and easy handling. Full AF is capable with lenses having a maximum aperture of F/4.5 or brighter. (Manual focusing will be required with lenses of smaller aperture.)Placed between the camera body and lens?? a teleconverter contains a set of optics that will effectively increase the focal length of a lens by a specific amount. Common magnifications are 1.4 times and 2 times?? but the Kenko teleplus PRO 300 AF converter has a 3x magnification. For example?? using a 2 times (2x) teleconverter will increase the focal of 300mm lens to 600mm. The Teleplus PRO 300 converters are made with high quality multi-coated optical glass supplied by Hoya Corporation?? the worlds largest manufacturer of optical glass. These glass elements are  designed to m