Originally posted by DeadJohn If the Pentax FF uses a conventional DSLR mirror design, no light hits the sensor until after the shutter is released. Things need to be in focus before releasing the shutter so a separate PDAF module is required.
If the FF is a mirrorless or translucent mirror design, then on-chip PDAF becomes meaningful.
Ah, sorry, you are quite right although don't Canon use some kind of on-sensor system in some of their models? I guess the writing's in the wall for the poor old OVF, though. The kind of abilities being introduced on these new sensors might be very hard to replicate using traditional methods.