>>3545798https://www.flickr.com/photos/smigol/48596214626/The new Ektachrome E100 has a great H-alpha response which means emission nebulae should be captured beautifully.
Provia 100F is very good for blue targets but otherwise has a mediocre H-alpha response compared to Ektachrome E200 which was the standard slide film for DSO astrophotography at the time. Ektar apparently has a good response for DSOs but I haven't seen any examples yet. A film to look forward to is Acros, which is the more-than-worthy successor to Kodak's Technical Pan. It has a great blue and green response, and an okay red response. It also does not need to be hypered because it had very good reciprocity. People back in the day used to stack gas-hypered techpan frames with Acros frames digitally to make up for the red response or make RGB frames.
Looking at your star trail photos, you're going to have to figure out how to time your exposures to get as much detail as possible without the sky fogging up which will ruin your DSO frames. To do that, you will have to sacrifice a roll to bracket for the sky.
Jerry has an article about setting up exposures here:
http://www.astropix.com/html/i_astrop/film/exposure.htmlHe's the go-to for starting out at film astro nowadays.
For on-the-budget tracking, you can do the old manually tracking an object with an EQ mount for a very long time which was the standard back in the day before computerized mounts and good motor drives. Or you can be badass and use a barn door mount which can be made for less than 20 dollars. They were used to take pic related (thread:
https://www.cloudynights.com/topic/329865-north-america-with-barn-door-tracker/). Remember that you don't really need 48 hours exposure to capture a glimpse of nebulosity, it all comes down to the film.
tl;dr read jerry's articles, read about nightfly's tests, go to cloudynights' film astro forum and lurk there faggot
