Thank you Sam. When I took these subs last night, the temperature was 77F, humidity 23%, dew point 41F. So, with the cooler off, I wouldn't expect dew to be a problem, and normally up here in the high Arizona desert it isn't. I do use a dew shield to block environmental light sources from creating artifacts. I examined the glass for any residue and didn't see anything, but cleaned it anyway. I'll check the glass visually tonight.
I use a 5A power supply that was plugged into the camera, even when the cooler was switched off. I'll also try exposures with the PSU unplugged.
