Originally posted by theperception2008 while Fuji's X-trans sensor has low noise and no chroma noise that I can see
I am very wary of Fuji's ISO numbers.
If the X100 is any guide, Fuji camera's stated ISO's may have VERY little connection with their actual ISO. They may say they are at IS06400, but the camera may be running at something considerably lower than that.
Pic related, from Dxomark.com, comparing the ISO stated/actual of the X100 (the most recently measured APS-C sized Fuji) to the K-5.