Originally posted by gazonk One possible explanation (mentioned earlier in this thread, I think) may be that it's a 1/2.33 crop sensor - that would make more sense.
AFAIK, there is no such CMOS sensor on the market.
Anyhow, going smaller, towards lower image quality, with a system
that is the future hardly is likely. Pentax with it's limited resources is already having to provide for two mounts - K and medium format, they're only going to add one more mount for themselves to worry about, and that has to be large enough for at least APS-C, hopefully for FF. Putting a unnecessarily small sensor inside would not make any sense whatsoever as it'd not only hamper the image quality, enforce creation of lenses that would be compromises (as they'd have to work well with very different image circles, thus be larger than necessary, and more complicated to optimize), and it would not even bring the price of the system down (hard to imagine an obscure low production sensor to be cheaper than an APS-C mass product is), nor size at all.
When
the camera comes out, it'll almost certainly have an APS-C sensor, though, I do have hopes that they'd reallly do something different and make the first model a pro(sumer)-model with a FF sensor. I'd buy one the day it came out (assuming EVF and SR included) and a Leica wide/normal as well to break my bank account...