Thanks so much Adam and Nik. All this information is really helping me.
Nik, I will add those exposures to my library. They don't take too long to do.
Adam, I heard that for this camera flats need to be rather long, around 3-5 seconds. So I guess if ADU goes too high, I just add sheets of paper? Does it matter if I place 2 sheets of paper side by side? Or will the overlay create a line straight through my image? I might buy some A3 paper, and problem solved