In reply to ryanconroy: if your a student for experimental stuff dont spend £10 on film and development, you can get film from the poundshop, or spend a little bit more for something better from 7dayshop/ebay, tesco develop for a pound then scan it at your education establishment. for star shots look on flickr at the exif data of what other people are shooting at (but note if the exif data says 30 seconds and there is a trail it is a series of 30 second shots stacked), also sometimes people state like here:
http://www.flickr.com/photos/hairy_rob/5523890709/in/photostream
When I started with film I did night shots I used my digital camera on ISO 3200 for one second to take a picture then if this was exposed right I could do say iso100 for 30seconds on my film (and adjust further for difference in aperture) if the test shot was too light or dark i could guess how many times too light or dark it was and adjust accordingly.
With film you can get away with a couple of stops either side on the exposure, so for a 1 minute exposure night scene you will get away with anything from 15 seconds to 4 minutes, so you don’t have to be as precise as you might think, also for star shots this means you will getaway with huge differences in time without much problem with the foreground.
Reciprocity failure is your biggest enemy, but many modern films don’t have that big failure under a few minutes for night scenes, and for star shots it helps not blow out the foreground and the stars are moving anyway so don’t really count in the reciprocity failure.
