Ideal for wildlife or outdoor sports photographers, the new Canon EF 100-400mm f/4.5-5.6L IS II USM is an impressive update of the original version of this L-series lens, which was first introduced in 1998. The biggest change in this new version is the upgrade from a push-pull zoom to a rotation-type zoom ring. The RF 70-200 f2.8 or f4 is not compatible with the 1.4 or 2.0x extenders. Your current choices would be: RF 100-300mm f/2.8 L IS USM - TC's can be used with full focal length 100-300. RF100-400mm F5.6-8 IS USM - TC's can be used with full focal length 100-400. RF100-500mm F4.5-7.1 L IS USM - TC's can be used 300-500mm only. RF400mm F2.8 L IS USM. The Digital Lens Optimizer is also available for images shot with an extender attached to a compatible lens. You cannot use the Digital Lens Optimizer with multiple-exposure RAW images created on the camera. EF cinema lenses (CN-E lenses) are not compatible. Shop for canon extender ef 1.4 x ii at Best Buy. Find low everyday prices and buy online for delivery or in-store pick-up Re: Canon 7D Mark II, 100-400II lens and 1.4III extender In reply to PK62 • Jul 26, 2018 I just ordered a Tamron 1.4 Pro converter from Adorama for my Tamron 100-400 and Canon 7D MKII and after connecting the converter to the lens and then to the camera body, I get a firmware update warning. After further testing, Sigma has concluded both autofocus and optical image stabilization (for applicable lenses) work 'without any issues' on the following lenses when used with Canon EOS R mirrorless cameras via the EF-EOS R mount adapter or Control Ring EF-EOS R mount adapter: DG Lens - SIGMA 12-24mm F4 DG HSM | Art 1. The Canon extenders (Canon does not make "teleconverters") almost always work with third party telephoto lenses in the EF mount that are compatible with their own maker's TCs.¹ Such telephoto lenses tend to have enough clearance in the back of the lens for the Canon extender to fit. mSAKx.