best way to learn is really trial and error.
most night shots I try to do a couple different shutter speed to see if anything else different comes up in the print.
I usually would rather overexpose a shot then underexpose as at least you can see and guage better.
A lot of times with Moon type shots the exposures can be like 15 minutes or so. 15 seconds wouldn't capture to much unless it was a full moon or something.
I threw in some photos to give you an idea of the shutter speed.
They look blue because I'm retarded and scanned them in as color, not B&W. So just pertend they don't look like shit....
30 second exposure
Seriously, though, the best way is to just take more and more pictures. Lots of film. Some camera will take picutres slightly different and that will change depending on what film you used as well.
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