awe! beautiful! You must be sooo stoked!
2 mins exposure at 400mm? A-Ma-Zing! Didn't think that were possible with a Polarie.
Which tripod model are you using exactly?
I am currently testing a Walimex/Samyang (and other names)
500mm 6.3 .
(With a T2 adapter it fits on almost every camera model; mine is a Sony Nex-5N and I found the T2-Adapter by Kiwi-Foto being the one that finds the sweet focussing spot on the sensor. )
Ultimately, I would like to go Polarie, too, but so far am a bit reluctant because this lens offers no Image Stabilisation and is VERY hard to focus real tight.
So I wonder what the inevitable tracking movement of a Polarie would do to the focussing...
and what tripod would suffice, yet be portable and affordable...
Again, your images are super great!