Curious what the two exposures blended were. Going to be doing some shooting in possibly similar lighting/topography soon.
I don't remember the two exposures off hand, but I think one was like 20sec at f/2 iso400. The blending is done like HDR where you just bracket and stack. But in this case it was just the two exposure(sky + canyon) and there was about a 6 stop difference(more or less). There was a moon out and that makes a difference also.
Hope that made since.