The recently announced Canon 70D ($1199 DSLR) is the first camera having an on sensor usable phase detection AF area that covers 80% of the frame. On paper this sounds like a sort of holy grail solution for mirrorless cameras. There are many advantages like:
- AF works at apertures down to F11
- AF covers 80% of the frame
- AF works in light levels as low as 0 EV
- Can work with face detection to keep moving subjects in focus
But Panasonic engineers came up with a similar solution described in US patent 8482657 (Click here). The patent contains plenty of images and description for the more advanced tech friendly readers. I don’t think that sensor will be used for the soon to be announced GX7. But I am sure the next GH may feature exactly that kind of on sensor phase detection feature.