A new video by a tester in Japan shows the a9's Eye AF (in AF-C) tracking working remarkably well with a single subject, tracking the subject's eyes all the way to the edges of the frame. Here are three reasons we're very impressed, and a couple reasons why we're still left a bit ambivalent: What we like: The a9 continues to track the subject's eye when all it sees is his profile.

It's quite robust, so we expect Eye AF on the a9 to stick to the initial subject better.

It tracks the eye at 20 fps (thanks to AF calculations performed at 60 fps even during bursts), while the a7R II's Eye AF-C falls apart in continuous drive.

When the subject turns his back to the camera, the camera doesn't jump off to the background, maintaining focus at its current position instead.

What we don't:

There's still no dependable solution for when you have multiple subjects in the frame. Though you can use this workaround to select which subject you want the camera to target, it's prone to erratically switch subjects. Here's a far faster way to select the subject to target. And what's more: Dual Pixel AF sticks with that face.

When the subject in the video turns completely around, the camera stops tracking him altogether, unlike Canon Dual Pixel AF which uses enough 'fuzzy logic' to stay on our subject. Although we're happy that in this example the camera doesn't jump off to something else, if there were another face in the scene it likely would have.

Our request to Sony:

Be robust enough that when the camera no longer detects the eye of the original subject, it still generally tracks that subject. This should be possible as the camera has phase information indicating the distance of the general subject matter around the eye its been tracking - but now lost - hasn't radically changed. *

Furthermore, retain some remembrance of the facial features when Eye AF was initiated so as to re-attain eye focus on that subject when he or she looks back at the camera.

*For those preferring the camera's current behavior of jumping to another eye in the scene if the initial one is lost, perhaps Sony could offer a setting to customize Eye AF's behavior. Either way, though, it's hard to imagine a case where the photographer wouldn't want the camera to return to the original subject when re-detected.

2017-5-17 13:00