Preliminary first tests Z7, Auto-Mode AFC, 80-400 G, BBF:
1. Eye tracking does not work on brown horses - expected. This included close up portraits.
2. Strongly backlit Black cat up in tree looking down at me - 2-3m distance. Burton's bright yellow eyes blazing in his black face! With both BBF and custom spot-exposure (Fn1), the camera failed to grab focus at all. Yes, Burton is a challenging subject who tests, rather stresses, my skills on backlit animals, but I do know the Single-Point AFC + spot-exposure custom settings in the D850 grab focus, and very fast.
3. Gray Burmese strolling towards me from 30m. I tracked him successfully all the way. Eye AF kicked in at about 12m. I had to zoom out to keep him in the frame
4. Ginger and gray Burmese sparring and wrestling at 3m. Here I found Eye tracking is highly sensitive. This mode snaps in and out between the auto-tracking blocks if interrupted by cats turning their heads rapidly, and if a paw covers a face. As soon as even one eye of the focal cat reappears the cursor focus grabs back on in Eye-mode.
5. Sunbathing cat grooming- Eye-AF tracks the rollicking face ie keeping on his eye. If he rolls on his back, Eye tracking crashes out back to Auto blocks. In this 1 case, the Eye AF failed to pick up the eyes in this orientation (still to be trained on these lessons, one asks?!).
7. Both Cats dozing with eyes closing shut. Occasional blinks. Eye AF still recognizes the slits. It can also recognize cat in profile if enough of just one eye is visible.
8. Flock of white geese: dark eyes against white plumage. Distances up close to MFD of the zoom, which allowed tight framing of their heads. AF sensor works mostly in Auto-Area tracking but kept a sharp focus and Eye recognition kicked in sporadically (thinks it's got a cat?!). This included a goose looking right into the lens with both eyes.