Hello, I intend to take my Pentax 645N to an impending trip to the Arctic primarily for shooting the Northern Lights (although I also intend to shoot landscapes and wildlife). I would love to capture the lights on slide film and from the research I have done, it appears to me that there is only one "practical" choice: Fujichrome Provia 400X pushed to 800, 1600 and 3200, especially given that I have a max aperture of f4.5 on my FA 45-85. My question mainly concerns reciprocity failure compensation. Fuji lists no compensation upto 1 min of exposure (I expect most of my exposures to land within 1 min) and 1/2 stop for 2 mins. Does that hold for pushed film as well? I would appreciate your input. Any other advice on the subject would be welcome as well as I would be miserable if I came back with rolls of slide film with crappy shots of the lights. Thanks a lot. Avi P.S: my primary shooting gear for the lights would be my Nikon D300+Tokina 11-16 f2.8, so it won't be the end of the world if I can't get many good shots with the Pentax. But it sure would be nice!