I currently shoot with a Nikon D7100 which obviously has a crop sensor. I have the two kit lenses with it:
15-55mm 1:3.5-5.6 GII DX VR
55-300mm 1:4.5-5.6 G ED DX VR

I'm looking for a lens for better f. so I can attempt some astro/night photography. What would you recommend that won't break the bank?
Thanks
Jess