The all-new Canon 1.4x EF Extender Mark III offers improved performance over its predecessor care of a new Spectra coating, a new internal procesor for improved communication between the lens, extender and camera, and protective flourine coatings on both the front and rear elements for enhanced weather proofing. When mounted it will boost a lens' magnification by 1.4 times while reducing the maximum aperture by 1-stop. This will turn an f/2.8 lens into an f/4 lens, for example.
Note: This teleconverter will only fit and work with a select list of lenses. Please click here for the compatibility chart of all compatible lenses.