Um, that's not what I want for now. I don't have the patience to take a long exposure like that.

Let me get my math straight. If I use sunny 16 rule on a sunny day, I'd get f/16 and 1/125s with ISO100 film. f/16 is 7.5 stops away from f/207 which would convert exposure time to (roughly) 2 seconds. And taking reciprocity failure into account, the correct exposure would be 8 or maybe 16 seconds (2 or 3 stops). On a cloudy day exposure time would be 16 or 32 seconds. You need to use 30 min exposure times during night time, right? That would give about 2 h exposure time with ISO25 film.

I think I start googling example pictures with proper descriptions.