SausalitoDog
Well-known
http://www.fujifilmusa.com/products/digital_cameras/x/fujifilm_x100s/specifications/
Number of effective pixels 16.3 million pixels
Image sensor 23.6mm x 15.8mm (APS-C) X-Trans CMOS II with primary color filter
Apparently, something is different. I am not a technician, maybe someone else could explain.
I still think it must have something to do with the combination JPEG/raw settings.
Isn't there someone else out there with an X 100 S who can chime in and let us know the size of the files he/she is getting?