quickmode

I was wonder Quick Mode vs Live Mode?

Live mode is the default AF method, contrast detect, of live view and video modes.

Quick mode is phase detect AF, you know this as the 61 point photo mode AF system on the 5D3. It requires that the mirror be down to AF, so if you use it in Live View, or Video mode, the live view will be temporarily interrupted, as the mirror comes down, AF is calculated, and then the mirror goes back up again. It is called "Quick mode" because phase detect AF is much faster than contrast detect AF on most DSLR's.
 
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