Bought it after long superior to the extender Canon EF 2x III and am totally thrilled, for now I have two Kenkos Ordered she might send back. Use the Canon EF 2x III Extender to my lenses Canon EF 70-200mm 2.8 IS USM II and Canon EF 100-400mm my 5DII. The 70-200 Everything works perfectly great pictures, great sharpness. The 100-400 I get 800mm, full surprise at Mondaufname, am very satisfied.