As Tony has just mentioned A/P is not cheap if you want very long exposures, but it is doable, I know that is not a word.
Anyway with a 50mm lens you can expect about 15 seconds of exposure before you see trailing.
Any more time than that, you will need to track, and be perfectly aligned to the SCP, (South Celestial Pole)
However don't be dis heartened, we all started off with trial and error, probably more error than success, well that was me.
You will very surprised of what you can capture with a 50mm lens of any type.
Leon