Quote Originally Posted by polyglot View Post
It looks (from the published curves) that New Portra 400 has at least as much speed as Portra 800. So you could expose P400 at 800 and probably be quite happy. Since you're scanning it, C41 gives you a lot more latitude than you would have with a chrome, especially if the dynamic range is over-expanded by push processing in order to bring the speed up.

Provia 400X reportedly pushes very well, certainly to 800. You gain some contrast of course but I'm not sure that's a problem for northern lights - just make sure you don't have any artificially-lit structures appearing in-frame to blow out.

10 days isn't much but I bet you could shoot a roll of each at 800 in an afternoon and have them developed/scanned well before you needed to leave. Only you can judge the level at which grain is or isn't "acceptable" for your purposes...
Hmm...thats interesting. So what you are saying is I can underexpose Portra 400 1 stop and develop without pushing. My initial foray into Portra 400 was for exactly those reasons. I saw results: http://filmphotographyproject.com/co...g-kodak-portra where Portra had been severely underexposed with either no push or a 1 stop push. I was astounded by the results.

I tried the same (sent in my film to E-Six Atlanta) but was super disappointed. I underexposed 3 stops and pushed 1 stop and 3 stops respectively on 2 rolls.....I was disappointed with both results. But based on what I saw from my 1 stop experiment, I can believe that the film will handle 800 well without a push. But I probably will overexpose slightly (maybe 1/3 stop) just to be sure.

But the results were a bit confusing from the 1 stop push experiment. Scenes shot in sufficient light came out fine, but those shot under low light came out with very thin negs. This could be a metering issue (I use the Pentax 645 meter without an external confirmation).

I think I might get a couple of rolls of Portra 800 along as well. Unfortunately 10 days is not sufficient to run my tests, since I have to mail my film in for development and that would take time.

Thanks a lot! This definitely helps.