I had some specific questions about ISO 800 film that I wanted to run by you guys. I have searched the forum for the same topic and although I found hits, it does not address all my concerns.

I am off to Alaska in 10 days to shoot the Northern Lights. I really really want to capture the lights on film (not to worry....I have a solid Nikon D300 as backup). My gear is a Pentax 645N with the 45mm f2.8. I am going to shoot wide open. I want to stop here because this is not a "how to shoot the lights questions" and I am aware of the limitations (I was in Alaska last year as well).

I already have Portra 400 (although I am not a huge fan of C41 film) and Fuji PRovia 400X slide (I am madly in love with slide film). I am looking for an ISO800 film as well and came across Portra 800 as a choice, but user opinions are wildly varying from "no grain" to "unacceptable grain", so I am left without a reliable baseline....

I DO NOT want to push and introduce grain in my shots if possible. I tried an experiment with Portra 400 pushed to 3200 (albeit a bit aggressive) and I absolutely hated the result....too much grain.

My questions (I always scan my film, so am looking for a solution conducive to scanning):

1. What is the verdict on Portra 800 when shot at box speed? Underexposed 0.5-1 stop? Would it need pushing under underexposure or can it handle that, followed up photoshop tweaking?

2. Is it advisable to push Portra 400 and Fuji Provia 400X to 800? Again: opinions are skewed, so I don't know what to believe. I dare not push beyond 1 stop since I don't want to risk it given the importance of the subject. Although I want to avoid pushing, if the lights are too weak, I may not have a choice.

I would REALLY appreciate your valuable insights. I hope to come back with some memorable images of the lights captured on (preferably) slide and C-41 film.