Airbus3464 years ago000I use a Canon R6 with the RF 100-400 F5.6-8 IS USM. Can I use the Canon EF 1.4x III.Show in original language (German)Kamil Taylan4 years ago • purchased this product000purchased this product Helpful answerI don't know exactly, but I don't think so. I use the combination EF and M. It works. You can get an answer to this question at the Canon Shop.Show in original language (German)Commentteodorwick4 years ago • purchased this product000purchased this productNo, unfortunately you can't.Show in original language (German)Comment