Sony's full-frame line, namely the a9, a7III, and a7RIII are getting an upgrade to their AF systems courtesy of the a6400.
Two major features that Sony announced with the release of their latest compact crop-sensor camera are carrying over to their higher-end line via a firmware update coming soon - Real-time Tracking and Real-time Eye AF for the a9, and Real-time Eye AF for the a7III and a7RIII.
According to Petapixel, Real-time Tracking is an artificial intelligence-based mode that is capable of discerning a specific subject in the frame, in order to stay locked on that subject. Real-time Tracking uses a number of different functions, such as subject tracking, eye detect, face detect, and more, to detect the colors, distance, patterns, and other factors in the frame.
The system is demonstrated in this video from Sony Artisan Patrick Murphy-Racey, showing how impressively the Real-time AF recognizes and tracks a subject moving around in the frame, even while that subject is bobbing and weaving very quickly and covering up her face and eyes.
[embed]https://youtu.be/aHmuJLVN7JA[/embed]
Real-time Tracking will only be available in the firmware update for the a9, but all three cameras are getting Real-time Eye AF.
Real-time Eye AF is an upgrade to Sony's existing Eye AF system, also utilizing an AI-driven focus system to recognize and track a subject's eye, maintaining a sharp focus. In AF-C mode, the camera will be able to continuously recognize the subject's eye wherever it moves in the frame, even locking back on quickly if the eye gets lost behind an object, or the subject turns around.
The a9's firmware 5.0 is expected in March 2019, with a 6.0 coming in the summer to further expand the AI capabilities of the camera.
The a7III and a7RIII are getting the 3.0 update in April 2019.