Hello.
according the A7s catalogue.( In sony Korea official website)
http://store.sony.co.kr/handler/ViewProduct-Start?productId=32827460&intcmp=Main_ì¸ê¸°ì œí’ˆ02_140625_ILCE-7S
'>
All mode of the A7s has the Full-Pixel readout. (without Pixel-binning).
but, FF60p(60i) mode is full-pixel readout with pixel-binning.
I think,
A7s's pixel-binning is cause of moire, softer image.