Regardless of the current Mark III AI Servo jamboree, I have wondered: how would you improve AI Servo? What functions, settings and algorithms would make AI Servo "perfect"? Let's think 10-20 years to future.
What my dream AF would do is to understand physics.
The "stupid" things AF systems do are done because AF does not have any connection to world we live it. So why not limit possible AF movements based on physics rules? To tell a camera this it would not have be complex AI, it could be put down to simple settings that limit AF movement after initial AF lock. The camera would know that AF plane cannot suddenly move x amount of distance to new direction because that is not possible.
User would tell AI Servo what kind of subjects to expect.
Directional movement mode
Inertia, acceleration and G-forces govern subject's ability to move in the world we live in. In "steady movement" mode AI Servo would know to expect natural movement and direction changes that do not exceed physics rules.
If you shoot a bird flying there is no way a bird would appear 20m behind it and then back in 1/10th of a second. When you shoot a runner, there is no way a person would move 10km/h forward and while doing that move back 1m and forth 2m few times a second!
Then you have cars and trains and planes, they do not move back and forth, they move to certain direction with speed that can not change from x to 10x in a second, even if they crash! When someone throws a frisbee the item follows physics and does not warp here and there.
The could be additional custom functions for setting expected speed ranges. If you shoot F1 you set speed range to 50-350km/h. If you shoot running man you limit speed range to 1-15 km/h. The camera would know from that setting where it is possible for the subject to be in certain time lapse.
Even if the camera lost the focus lock it would know where to go and what change of position to expect. It would be able to guess the next subject position perfectly based on less actual AF locks. If it locked to point X and later to point X+1, it is impossible that the subject is next in point X, so it must be in point X+2.
Localized movement & f-focus mode
With these modes AI Servo would know that the subject is mainly still but prone to move a little here and there. It would sniff for sudden direction changes but do very small adjustments.
With f-focus setting it would "focus with aperture": make aperture smaller (higher number) to cover the guessed swaying change and depth and if the movement stops change aperture back.
These modes would cover machines that have complex parts and move random or unidirectional manner but stay practically still (pistons, amusement part vehicles, merrygoarounds). You could apply this to situations where you have subject staying relatively still: riding bulls, kids playing, musicians, politicians, stand up comedians.
Any other ideas?