Thanks for your comments Anthony. Finding the right balance between foreground (subject) and background (stars) can be a real challenge. I guess at times it can be a matter of which you want to emphasise. Darkening the sky can highlight the foreground, a dark foreground will highlight the night sky. It can be what you're trying to achieve that determines the way it's presented. The wrong lens gave me less to experiment with, so yes, returning with the right lens would help but I think I'll leave this one for someone else and move onto another location.