We just found an interesting new patent. It seems that Olympus is working on a double TTL and contrast autofocus system which do work simultaneusly:
“It is to be noted that the TTL phase-difference AF and the imager AF have the following characteristics, respectively.
The TTL phase-difference AF is the AF at a speed higher than that of the imager AF.
The imager AF is the AF having a precision higher than that of the TTL phase-difference AF.”
“an automatic focusing device is disclosed in which the TTL phase-difference AF is combined with the imager AF to perform focusing control. Specifically, in this automatic focusing device, after coarse control is performed by the TTL phase-difference AF, fine control is performed by the imager AF.”
This would be possible with the use of a half mirror which reflect portions of lights to the Phase Detection Sensor.
My speculation: would that camera not be able to record video using the faster TTL autofocus?