Hi Leon
CWB's are only valid for the light conditions under which the CWB was taken.
If you shoot your astropix in raw then CWB is irrelevant as the camera doesnt apply the CWB to the raw data.
If you shoot in JPG then the CWB is applied to the data.
I only use CWB for terrestrial jpg shots with my Hutech modded 40D and leave the camera set to AWB when shooting raw astropix.
