Canon 6D Dominates in Low Light Focusing Test vs 5Diii vs 5Dii vs Nikon D600

My 5D2 beeps when it gets focus.

I just got to try out my 6D. I turned off the lights in my bedroom and it failed to lock focus. Outside two hours after sunset I had trouble locking focus in my backyard even with a glow in the cloudy sky.

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-Bill