I am fascinated with startrails for some odd reason, and cant wait to get to my farm and try to catch some. BUT, I dont want to get the negs developed and end up with 24 shiny black squares that could have been in a past life something called "pictures". I would be using a 400 film with my old K1000. What aperture is a good starting point? How long of an exposure? Keep in mind I only have the default 50mm lens, and a 1:4 macro.