I've got a sheet of 5x4 Portra NC that's giving me a little trouble. Nothing I can't handle, but I'm curious if this is normal for this film and if it is, what is normally done to correct it at exposure time. The image is a late fall / early winter scene of fall color with snow and some blue sky showing through the clouds. When I balance everything to get the snow and clouds white, everything else falls in line with the single exception of the blue sky. That is, the whites are white, the grays are gray, the greens and yellows and reds are all fine. The sky blue becomes cyan however, which is somewhat disturbing. No filters used during the exposure. Is this normal for this film? I don't have a lot of experience with it because it's so expensive. I will say that it's tack sharp and hardly any more grainy than 160PortraVC. But why the oddball color balance problem?