I'm looking at the specs of the recently announced Sony A7 against the specs of the NEX-7, and I am confused about one detail: the amount of shots it can take per second.
The NEX-7 can capture 10 shots per second with its 24MP sensor. The a7 can capture half of that, 5 shots per second with its 24MP sensor. As far as I can tell, the main differences are that the a7 houses a full-frame sensor against the APS-C sensor in the NEX-7 and that the a7 can record 14-bit RAW images (I believe the NEX-7 can record 12-bit only).
I don't think it's the sensor size that makes the a7 slower, as the end result is still a 24MP image so is it the difference between 12-bit and 14-bit? But this confuses me somewhat as I own a D7000 that I can set to record 14-bit or 12-bit RAW's and the camera can keep the same frame rate regardless of being set to 12-bit or 14-bit. I can also make more sense of a camera with a mirror and a mechanical shutter having a lower frame rate because they have actual moving mechanical parts, but then comes along something like a D4 or 1DX that can exceed 11 shots per second!
So what is the real limit for this statistic? The memory used for the frame buffer? If that is the case, does it mean that the a7 has a less capable frame buffer than the NEX-7 even if it's a more modern, more expensive camera? And would it be possible to implement some really quick, ample memory to increase such a buffer? I recall some Nikon cameras increasing their burst-rate when a vertical grip is installed. Is that what the grip is adding on them? More memory?