Adrian
I'm going to assume you are inferring to magenta/green color shift that is occurring
across the image and not fringing or chromatic aberration as Garry is responding to.
If this is the case then I think (bear in mind I don't own a DB but use them regularly) that
you find this 'lens cast' evident,to varying degrees,in most wides (some have reported seeing it on
Hasselblad Apo Teles,as well) and near wides when using Phase backs.
There is a very simple 'fix' for this in Phases capOne software called,LCC correction.
This involves taking an exposure with a translucent white disc placed over the lens in the
situation where you anticipate the cast occurring.
You then open this file in C1 and neutralize the file using the LCC correction after which
you apply this correction to all images taken with the same lens.
Very quick and efficient once you run through it a couple of times.
These custom lens profiles are then stored within C1 and can be applied to images using the same
lens under similar conditions.
I have seen the color cast with the SWC,as you have, the Arcbody with 45mm and an
older V 50mm blad lens.
The presence of the cast,generally,diminishes with longer focal lengths
If you navigate your way to the Knowledge Base at PhaseOne.com you will find a much
cleared overview than I have provided here.
Mark