No flat, no cropping. Just a quick process. I am happy with how it turned out so far. Going to try and grab some more lights of this to increase the SNR and see if that'll help.
Jerry - Why a flat would cause the banding? Flats were taken during same session, same camera orientation, temp etc
It depends on how you take your flats and what the light source is.
Remember in the old days of Television with cathode ray tubes? If you took a picture at a shorter exposure than the scan rate, you would get diagonal lines in the image.
I've seen bands in some flats I have taken that were illuminated with an LCD screen.
Probably not a similar process happening between a CRT and an LCD, and I don't understand the electronics of how an LCD works, but there are plenty of things that go wrong with flats.
Try taking your flats and using the Eqaulize command in Photoshop.
I'm not saying the banding is definitely from your flats, I'm just saying that's the first thing I would look at.
And it looks like you still have the problem in the last pic you posted without any flats at all, so it's probably not the flats.
Some of the old 20Da cameras had a problem called the "dark river" which were dark bands that looked something like what I see in the last image you posted. It was a nightmare to get rid of.
There's plenty of things that can go wrong with the sensor and electronics in these cameras. It's a wonder that more stuff doesn't show up in the crazy stuff we shoot.