Hi Chris,
A warm welcome from a fellow D7100 owner
Here's our tutorial on
Hyperfocal Distance, which of course you may have already found!
I am guessing, with those lens choices, you do star trails?
In due course, you may find these threads helpful:
HELP THREAD: How can I post images here?
How to Get Effective Feedback for your Posted Images
I spent a (less than) 24 hour period in Belfast once, flew in (arriving at dusk), hotel, work meeting, flew out - no time to see anything.
I remember the big yellow cranes being visible from the city airport terminal building though.
Must return one day.
All the best, Dave