That said, if you don't care about seeing it in real time you can use a MUCH smaller lens and stack exposures. You'll likely want a star tracker (MASSIVE decrease in effort) to go with your camera, lens, tripod, intervalometer, and Bahtinov mask (cheap, makes focusing MUCH easier). https://www.youtube.com/watch?v=iuMZG-SyDCU is an excellent tutorial on how to do this without the tracker.