The Canon EF 1.4xII is not optically identical to the Canon EF 1.4xIII. Nor is the Canon EF 2xII optically identical to the EF 2xIII. He actually said the 1.4x I is optically identical to the 1.4x II. That is true. Yes, the 1.4x II and 1.4x III are optically different but there is not much difference in Image Quality. If you are going to use a teleconverter with your 70-200, I'd only consider the Canon Extender EF 1.4X III. Version lll is an optical upgrade over versions l and ll, which are optically identical to each other. Adorama.com has a used, excellent grade, Extender EF 1.4X III for $350, maybe no sales tax, KEH has the same for $311 plus sales tax. EF 1.4x III and EF2x III extenders are recommended for use with EOS Digital Cameras. *1: EOS-1D Mark II, EOS-1Ds Mark II, EOS-1D Mark II N, EOS-1D, EOS-1Ds Professional level. Optimised lens coatings, white heat shield coating. £ 719.99. Eligible for free delivery. Add to basket. Add to wishlist. ¹ Extender RF 1.4X is compatible with RF 100-500mm F4.5-7.1L IS USM (300 to 500 mm focal lengths only), RF 600mm F11 IS STM and RF 800mm F11 IS STM. The EF 2x models are not recommended for use with lenses with minimum apertures exceeding f/4. The extender instruction manual can tell you which combinations of lenses it is compatible with. You camera instruction manual should tell you which focus points would be available, which in this case I would expect none to be available in the viewfinder. Focal length extension for super-telephoto lenses. The Extender EF 2x III is specially designed to work in conjunction with L-series IS super-telephoto lenses, extending their focal length by a factor of 2x. The extender's design ensures there is no loss of lens performance or image quality. I just tried a RF 2x extender and, RF-EF adapter and a EF 75-300 lens and the Rx Extender won't attach with the adapter. Looks like I would also need a 2x Extender III or 1.4x Extender III to make this work. Thanks for all the advice. 12-11-2021 10:27 PM - edited ‎12-11-2021 10:55 PM. The EF 70-300L is NOT compatible with Canon's teleconverters - they will physically not fit on this lens. If you want to get an extended reach, then the RF100-500L is a brilliant choice for the R5 (at a cost), but if you want to stick with EF lenses, then I can recommend the 100-400MkII or This is straight from the manual. The TS-E 17mm F/4L IS NOT COMPATIBLE with any of Canon's teleconverters. All of their TS-E lenses are INCOMPATIBLE. -Demetrius. Current Gear: EOS 5D Mark IV, EF F/2.8 Trinity, EF 50mm F/1.8 STM, EF 85mm F/1.8 USM, 470EX-AI & 600EX II-RT. Retired Gear: EOS 40D. 1 Like. ciSaIS.

canon extender ef 1.4 x iii lens compatibility