theres lots of factors, location, moon calendar. Rokinon/Samyang lenses are pretty good, you need f.2 or even lower ideally to capture more light.Also post processing makes big differences in astrophotography. Im not an expert but I've read about it.
How to get the Milky Way Galaxy? I used a 16mm lens on an APS-C (Cropped Sensor) with ISO 3200, f/4.0 and 20sec.