Yes, sorry, David… I posted that earlier, but I keep posting new images without context.
I have a NexStar 6se, using a 2x Barlow, the Astrodon UVenus filter, and an ASI1600mm.
Until/before specified, I was not using the Barlow. Without the Barlow, I was using parameters, typically, of 6ms and a gain of 420 to 480. With the Barlow, I am using similar gain but an exposure of 45ms. My sense is that with better seeing, I'm best off using the Barlow and grabbing fewer frames, but with worse seeing, I need to grab more frames, which necessitates the faster frame rate and foregoing the Barlow. The factor of 7.5 difference in speed is owed to the change in focal ratio (worth ~4x) and how much UV is blocked by the glass (~2x).
All of the parameters vary depending upon conditions.
I have been trying to image right before sunrise, when the sunlight heats up the scope and creates tube currents, but the changing seasonal geometry is putting the sunrise behind a neighbor's garden, which is giving me flexibility there. Sometimes clouds block the sunrise, and on one occasion, I shot at about 11am, whipping a white towel off the telescope just in time to image, before the scope could heat up.
One of my overarching findings is that uncontrollable changes in weather and seasons (and my daily schedule) are preventing me from adopting a consistent methodology. The conditions have been favorable from about June 13 through now in mid-September, so I might say that Venus UV imaging is favorable for about six months per 19-month synodic period… a pretty good percentage of the time compared to Mars. I may say that Venus is the most rewarding object in the sky for me, and I may decide my next telescope based in large part on how it would perform on Venus.