Third Party Manufacturers / Re: Samsung NX1 - FF level quality in an APS-C?? Imaging Resource samples...« on: December 21, 2014, 11:15:28 PM »
FWC is dependent upon surface area...the surface area of the photodiode. With an FSI design, some of the pixel area is dedicated to wiring and transistors, which thus necessitates that the photodiode (the actual light-sensitive part of the silicon) become smaller. By flipping the die and etching on the back, the photodiodes can become larger, since the wiring is all on the other side. That increases FWC, which means for the same size sensor, with even the same size "pixel pitch", your actually gathering more light.
Thanks for the explanation. For some reason, I'd thought the surface merely translated photos into electrons, but that the electrons were stored below the surface.