Here's a stack of 52 x 60 sec subs taken with a D810A through an older D-series 180mm prime at f5, iso 1600. I used a polarie tracker on a manfrotto tripod. Fun though it was, compared to the results I get through the Takahashi FSQ106 with a reducer means I will have to revisit this as a mosiac.
I've had a couple of different goes at processing this, the most successful has been to use Nikon's Capture software for pre-processing and then using Pixinsight for registering and integration. Doing it all in PI seems to kill the red channel.
High res version here:
http://www.astrobin.com/220470/
Happy to take constructive advice!
cheers,
Andrew.