The canon ef 200 400mm f4 l is usm lens with internal 14x extender is a top flight lens developed primarily for professional wildlife and sports photographers who desire finest possible results and finest possible lens uncompromising in design ethos lens possesses 33 elements in 24 groups and features fluorite coating sub wavelength coating and ultra low dispersion ud technologies ensuring colours remain sharp and precise throughout lens range 14x extender makes lens highly versat