Originally posted by Kunzite This is already being done with on the sensor PDAF. Refining that technology is IMO more logical, than going back to a separate AF system.
Doing it the other way around - making a SLR which would use the main sensor for AF (and other things) will reduce cost and calibration issues. Perhaps still not good enough in the immediate future, but a viable idea.
Unless there's something fundamentally wrong with the on-sensor AF which I'm not aware of.
I don't think there's anything wrong with PDAF on the sensor, but even though it shares a name with the PDAF systems on DSLRs, there may be some significant differences in the way they work. Take the Sony A99, for example. It has three ways of focusing: CDAF, on-sensor PDAF (102-point) and the dedicated PDAF sensor using reflected light (19-point). The A99 can only
acquire focus using the 19 points on the dedicated PDAF sensor. It uses the 102 on-sensor PDAF to track objects that move outside or between the 19 points once focus has been acquired. The A99 was released in 2012, so at least at that time, there was a difference in how the systems worked.
Metering on SLTs is done using the imaging sensor and there is no need for a dedicated metering sensor. In my experience, the K-01 metering is very consistent compared to the K20D I had before. I've read something similar in other reviews. So it seems that this make another component redundant without compromising capability.
A did a quick search to find out about front and back focus issues on SLTs. They seem to have just as many problems as DSLRs. Since all DSLRs can focus in live view now, I don't know why no manufacturer has been able to make the camera calibrate itself with a lens. You would just put it on a tripod and point it at a target. The camera would go through a routine of comparing focus at all PDAF points and figure out the adjustment itself. I'm sure it would fail sometimes, but then it would just inform you to choose a better target and try again. Am I being unrealistic here?