Originally posted by noel I thank all of you for your responses. It seemed like a case of underexposure. I've looked through other of my photos and there are always noise in the black, purple and dark blue areas....but I thought it shouldn't happen at lowest ISO?
Nonetheless, I will do a EV+1 and test out further.
I believe shadow and highlight correction can generate noise at low ISO.
You can't add +1 Ev all the time and expect good results. Depending on the scene, you may need no Ev, positive or negative Ev, and weak or strong settings. You have to get to know how your camera exposes and adjust as required. Make your best guess, then use your histogram to review and correct the next shot if needed.