As I noted under "MGD May Challenge #2" I have a question about Reciprocity Failure
while shooting to get a comparison between the 4 Kodak Portra emulsions.

I want to shoot all 4 rolls under the same lighting conditions and same 4 scenes.
I'll shoot 3 shots for each scene to bracket the exposures.
For most of the shots I plan, there is no direct sunlight and with the slower emulsions,
I may have to use a long exposure ... say 2-4 seconds, perhaps longer.
For artistic reasons, I'd like to keep the f/ stop fixed for each scene and get
a consistent DOF ... but I don't know if this will cause reciprocity failure in the film.
I will have to shoot all 4 rolls in close sequence to get fairly consistent light.
If I pick an overcast or mostly cloudy day, I won't be too rushed.
OTOH, On a bright day, I would have to shoot between 9 and 11, or 2 to 4 to avoid
extreme lighting changes between shooting the first and last roll.

MGD