Big AF improvements give Sony's new a6400 APS-C the fastest autofocus in town
https://newatlas.com/sony-a9/58065/
Sony has introduced a new a6400 model to its mirrorless APS-C sensor range. Cheaper than the a6300, the new camera borrows a much faster processor and autofocus system from the barnstorming a9, and adds a selfie-friendly flip-up screen to the mix.