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ha ha , yes I learned it all the hard way so I try and save people new to it the trouble.

A noble thing to do, most people hide their knowledge, or at least don't pass it on.
How long are your exposures?

It really depends on the situation but as a rule of thumb its best not to go over 30 seconds to avoid star trails. I average between 15 and 25 seconds depending on the lens, camera and phase of the moon. Here is a good explanation of the 500 rule https://petapixel.com/2015/01/06/avoid-star-trails-following-500-rule/

It makes sense. Ok, I'll have a look on that link.
Thanks a lot for taking the time to answer my noob questions :D

Anytime, good luck

Thanks :))
Best of luck to you too.