Did some experimenting with ADU targets for flat frames. The full well of the KAF-1603 in the QSI 516 is 100,000e-. Gain is 2.6 e-/ADU. So, full well of a single pixel binned 1x1 will occur about 38,500 ADUs. It is best that ADUs reach about 80% of full well, which is a little over 30,000 ADUs. For higher binning values, full well will be close to 65,000 ADUs. A good target for flats there is about 50,000 ADUs.