What I have found, espcially is there is slight mix in lights. That I shoot in portrait mode, import into LR with a preset that is set to portrait and the contrast set to -10. If you use, like vivid, the camera adds some off colors. I then keep working with a low contrast, because as soon as I take it to PS, the contrast gets added with the processing. I always finish in LR, and if I still need a bit of contrast, I can add it then. Most of the time, I'm still lowing the contrast a bit, by like -5 or -10.
Some food for thought. I have been shooting with a medium gray background, and I still get some stray colors shooting other that portrait. I actually setup a shooting bank when it is set to portrait, and I also set the contrast a bit lower in camera. That way I can check the monitor when I'm shooting if there is any issue.
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Nikon D4, D200, Fm2, FM, Mamiya RB67.