I'm hoping to learn more about the dual-pixel CMOS focusing.
They introduced their hybrid AF system on the new EOS-M ... but it was just a few of the points on the sensor that had this. It worked, but the first version of the firmware had focusing a bit slower than people were expecting (they were expecting AF speed performance and while it was faster than contrast-detect AF, it wasn't nearly as fast as phase-detect AF.)
Canon recently released a firmware update for the EOS-M and I did see a video demonstrating the difference. The guy was focusing on a flower-pot in his window and then the building across the street and just switching between the two targets and letting the camera refocus as quickly as it could. With the "old" firmware, it was a bit sluggish. With the "new" firmware it was actually pretty quick.
Now Canon has this dual-pixel CMOS which seems to be a refinement in the design evolution of hybrid AF. I haven't seen any videos demonstrating it, but I did see a comment from one photographer who got to use the camera prior to launch who said "trust me... it's fast!" (ok -- I guess we'll have to wait and see some videos demonstrating just how fast it is.)
To be fair, this is only active in "live view" mode and it was mostly created for video purposes. In normal photography where you're looking through the viewfinder, you'll be using the 19 point AF system (all 19 points are "cross type" -- basically the same system the 7D had.)
Another feature that I caught was the SD card slot. Instead of a traditional SD/SDHC/SDXC slot, it's also a UHS-I slot. The UHS-I standard specifies a bus speed of up to 312 MB/sec.
So assume the RAW file size is an average of 25 MB. The camera has a continuous burst speed of 7 fps. You'd need a bus speed that can transfer data at 175 MB/sec or faster and the UHS-I slot _is_ faster! That means that you can shoot RAW in burst mode and the camera can transfer images as fast as you can shoot. Unlimited shooting in continuous mode even when shooting in RAW. That is a first! BUT... you can't actually do this BECAUSE while the bus technology is there, the fastest cards you can buy are still only clocking in at just shy of 100 MB/sec. Still... as faster cards come out, the camera is ready for them. It's not Canon's fault that you can't buy a 200 MB/sec card from Sandisk or Lexar.
Previously, the only way to get transfer speed of around 100MB/sec was to get a camera that used CF cards because SD slots just weren't that fast. Even my 5D III (which has both a CF and SD slot) only uses traditional speeds in the SD slot (the CF card slot is fast, but not the SD slot.) The 6D also has a UHS-I compliant slot.
Nice review, Don! I love my 60D and I'm forcing myself to hold out until I save up enough for a FF. But the 70D really does seem like a solid step up - particularly the new AF system. As a parent of three young children, my biggest "gripe" with the 60D is I'm rarely able to shoot video as they are usually running around constantly. I knew this limitation when I bought the camera so it's really not a big deal. Likewise, I bought the camera to take still photos. That being said, I'd love to retire my Flip (except for underwater) and Kodak Playsport for random family video stuff.
Do you think it's possible that we'll see this AF technology on the next generation FF cameras? I may be wrong, but from what I've seen in demos, it needs a touch-screen display to shift focal point. I'm having a hard time picturing the 5dm4 with screen that flips out, too. Would love to see it though!
One other question about the 70D: How does using the battery drain of wi-fi streaming live view compare to regular live view? (question probably applies to 6D as well)