Thanks Ray, it was your thread that originally got me thinking and inspired me to ask more
I haven't yet found a way to analyse the raw pixel values in the raw files, but just going on PI's normalised values, but loading up one of the raws I took fresh this past weekend at a dark site and a bias file (and debayering both), the background values seem to hover around 0.033-4 whereas the bias file is 0.031...so it looks like exposing to about 25% just eeks it past the line. So if I understand it correctly it looks like I should expose for just a little longer from a dark site.
This is ignoring the dark current of course...which in the warmer evenings is noticeably higher than on the colder nights
