Can confirm it works perfectly and autofocuses at f/8 on the EF IS non-L 70-300mm. I don't think its a great teleconverter, if you have the compatible L lenses, you can use the Canon ones - which are higher quality glass. PhotosByHall's gear list: Canon EOS 7D Mark II Canon EOS 5D Mark IV Canon EOS M50 Canon EF 50mm F1.8 II Canon EF 17-40mm f/4 Canon Extender EF 2x III. Canon. Extender EF 2x III. Ammattitasoinen polttovälin muuttaja, joka lisää L-sarjan objektiivien polttovälin kaksinkertaiseksi. Canon EF 400mm f/2.8L IS II USM Canon EF 600mm f/4.0L IS II USM Canon EF 800mm f/5.6L IS USM Canon Extender EF 1.4x III Canon Extender EF 2x III Reply to thread Reply with quote Complain The 300 f/2.8 IS performs better with the Canon EF 1.4x II Extender and the Canon EF 2x II Extender than most if not all other Canon lenses. Adding the 1.4x creates a 420mm f/4.0 IS lens - a very nice focal length and max aperture - and yes, IS still functions with the extenders installed. Verdict. The Canon EF 200-400mm f/4L IS USM Extender 1.4x is a real whopper. It’s nearly twice as long as the Canon EF 100-400mm f/4.5-5.6L IS II USM and two full kilograms heavier, weighing in at 3,620g. Its main claim to fame is that it has a built in ‘extender’ or tele-converter, which you can bring into play via a simple lever at the The Canon EF 70-200mm F2.8L IS III USM is a professional telephoto zoom lens for Canon full-frame and APS-C DSLR cameras. A gallery of sample images taken with the Canon EF 70-200mm F2.8L IS III USM lens mounted on a Canon EOS 5DS R camera body. The Canon EF 100-400mm f/4.5-5.6L IS USM Lens has an excellent focal length range that includes the longest focal length found in a Canon zoom lens - 400mm. This long focal length and focal length range combine with very good image and build quality to make the 100-400 L one of the most popular serious wildlife and sports lenses Canon sells. Designed as a lightweight and affordable extreme telephoto prime for Canon RF-mount shooters, the Canon RF 600mm F11 IS STM is a versatile lens for casual wildlife and general photography. If 600mm isn't enough for you, it can be paired with Canon's new 2X extender for RF to become a very portable (and very slow) 1200mm F22. News Reviews Articles Buying Guides Sample Images Videos Cameras Lenses Phones Printers Showcase Forums Galleries Canon Extender EF 2x III Buying Options Canon EF 70-200mm F2.8L IS II USM Canon EOS 5DS Canon Extender EF 2x III If you believe there are incorrect tags, please send us this post using our feedback form . EFgdVZ.