Viggo said:
I’ve tracked kids in crazy action with face-detection with very very high hit-rate. Maybe you’re doing something wrong?
Across entire frame ?
Did you try to do that in extreme low light conditions ?
I do not argue about ability of 1DXm2 to track faces using mirror AF with dedicated AF sensor but you still limited to AF area provided by this sensor.
And still 1DXm2 has much less information from AF sensor for face tracking than a9 getting directly from sensor with high refresh rate.
My experience that A9 is doing that much better, but this is my personal feeling.
Someone else could have different experience but could judge only using both cameras.
I do not have any time to do any kind of scientific test, may be someone will do that at some time.
Also for BIF A9 is much better than 1DXm2 - it can catch bird immediately as it enters the frame and follow it across entire frame. So it is easier to follow bird with long tele lens - you do not need to keep it in center area of the frame - basically you have better tolerance/margin to follow the bird.