This is really nice Doug!
That lens looks like a corker for 400mm and with the APS chip ,hard to find!!
As Mike commented, the large version does exhibit some noise. Work on that and she'll be a beaut!!
What I like about this image is the minor planet/ asteroid zapping through, gives it an action look
and also the little reflection neb to the middle R/H side.
Super fov and just perfect for objects of this size and content.
All the best
Rich