63 zones vs RGB metering
It is possible that the larger sensors in Canon's metering array are more sensitive and allow for better low-light metering.
It might also be faster because of the way the sensors can be read continuously versus needing to read Nikon's sensor in much the same way as you have to read any image sensor. But I kind of doubt that's much of an issue, really.
The Nikons still have to use a separate array of a different type of sensors for the actual AF. The thing they do with the color metering array is help out with object tracking .
The idea is that they can decide where something has moved within the frame better because they basically have a low-resolution image sensor for their metering sensor, and it can be active all of the time that the mirror is down.
But the actual autofocus has to be done with a separate AF array below the floor of the mirror box, just the same way Canon does it. The AF sensor array has to use dual linear arrays for each AF "point", and the "images" projected onto those line arrays must pass through the split-image prisms and lens systems first.
So don't confuse the object tracking with the actual AF. But the Nikon system is still pretty clever IMO They've probably got a patent on it. That may be the real reason that Canon does things the way they do.-- hide signature --
Thanks Jim. What you said make sense.