Ben Scott
Veteran
Then why are you complaining about the camera? If you didn't have the time or resources to do the shot right, that is not really the fault of the hardware.
Because the noise in question is a product of the raw output crapping out at most things 2 stops or more under middle grey, not the exposure choice.
I've had to make this call many times when shooting where I know I need to keep the skies perfect, and I'd have done the same thing as the OP and gotten great results. Except not with the raw output, which is the devil.
EDIT: Berk are you finding the noise gone now with the hdmi?