I have shot this film at exposures in the 30 minute range. I can't tell you exact reciprocity compensation times, but I can tell you how I shoot it. I also have never noticed any colour shifts or crossover from long exposures. This is a wonderful film for long exposures. If, by chance, you over expose the film you have to really overexpose it for the highlights to block up. Mostly on over exposure you just get more shadow.

I rate the film at 50 iso and bracket in full stops toward over exposure.

Some examples I had on my hd. They are scans of slides of the actual prints. The prints are far nicer. I suspect the house is in the 1-3min range and the window is around 30sec to min and over exposed hence the detail...