You don't meter. Just set your focus on infinity, shoot wide open (F2.8 - F4.0), squeeze the shutter and count your seconds. Try bracketing some shots at 15, 20, 30, 40 seconds to see what gives you the best results.

I've had pretty good results with Provia 400X on my Pentax 645NII. These shots are from a not a very bright display, exposed for about about 40s and not pushed at all. I would probably recommend pushing a stop to 800.


Fish Lake Aurora by Anthony DeLorenzo, on Flickr


Fish Lake Aurora by Anthony DeLorenzo, on Flickr