Placed between the camera body and lens a teleconverter contains a set of optics that will effectively increase the focal length of any lens with which it is used the kenko teleplus mc4 af 20x dgx converter has the effect of multiplying the focal length of your lens by 20x turning a 300mm lens into an equivalent 600mm lens the mc4 af 20x dgx converter has genuine gate array ic integrated circuitry it means the converters unique circuitry maintains signal integrity between the camera b