Turns out there is a splendid work around: Unlike most other colour negative films Kodak Portra 400 shooting at ISO 640 and developed pushed 1 stop in normal C41 chemistry really brings out the contrast and colors. These days this is my preferred way of using the film. The dynamic range (contrast ratio) is increased at the expense of a slightly decreased latitude. In addition an extra 2/3 to a stop of increased ISO really helps out in hand holding medium format cameras.
Beware that unfortunately not all labs will correctly push c41 films.
|Kodak Portra 400 Shot at ISO 640 and pushed one stop in C41chemistry|
Slide show of some more pushed Kodak Portra 400