quote: Reciprocity failure does not mean color shift, it is that light falls off over a certain period of time. Exposure = intensity x time.
Somebody did their homework.
In the good old days long exposures would effect a films colors. Long exposures did cause alot of color saturation giving those tripod wedding shots at night, a beautiful color shift can't repeat any other way. The same with the night sky... Looks black to the eye but a beautiful blue to the film... Probably why everyone thought it was an effect of the light values. It was more an effect of the film's absortion of color saturation I think. I could be wrong though. I'm sure someone will correct me.
To me retroporcity (sp) means i add a stop when it goes past a minute. Up till then I just deal with it.