The 2x EX is placed in the same way and it allows the photographer to use the 70-200mm f/2.8 lens as a 140-400mm f/5.6 telephoto zoom lens, and the 300mm f/2.8 lens as a 600mm f/5.6 ultra telephoto lens.
TELE converters dedicated to the APO 70-200mm f/2.8 EX and the APO 300mm f/2.8 EX lenses increase the focal length by at least 1.4 times.
The TELE converters provide a larger focal length and allow greater mobility, which is useful for taking photographs of sport, nature and landscapes