Good to see you're putting the learning into practice. You've done well from inner Sydney, broadband imaging from a location like that will be tough to say the least. What mount were you using? Perhaps try longer subs with the lens stopped down to f8 and your field will be sharper with less coma in the corners of the frame. I do a lot of my imaging from a Bortle 6 location and I generally find 20+ 1 min subs at f8, 1600 iso, will generally give a reasonable result. Keep trying different exposures and ISO settings, you'll soon find out what works best with your mount and lens combo.
