Any tips on focusing to infinity - I can't see anything on the screen at 10X at these wide angles (except maybe the moon - which I would focus on if it's out).
I have a 5D m3 and I use a laptop, connected via cable to the camera, to focus. The EOS Utility software that comes with the camera allows you to drive the camera via the computer. One of the options is Live View, which can zoom an image on the laptop screen. Much easier than doing it on the back of the camera
(hope that makes sense)
I hired a Zeiss 21mm f2.8 a few weeks back. It uses manual focus, and it does have an infinity stop, like lenses used to have before auto focus. So, that was an easy one to use for night shots. A beautiful lens for such work. I'd like to compare it with the Canon 24mm f1.4, which is a great lens from all accounts. However, I hear there is an element of coma (at the extreme edges) of the 24. The Zeiss had very little coma.