I’ve been using ‘Back Button Focus’ for almost 25 years and today, even with the multiple AI autofocus choices available in mirrorless cameras, I still believe that it’s the best way to control focus. In fact ‘Back Button Focus’ is now even better than it used to be. Mentioned in this video : “Back Button AF With Mirrorless: Am I crazy?” by Steve Perry https://www.youtube.com/watch?v=OF1Ur1r2yBE&t=42s