When I have the time between shots I determine all three settings in the exposure triangle, but when I am moving quickly from well-lit to more darkly lit places, I turn on Auto ISO. I understand that my Maximum Sensitivity Setting is the highest ISO I would want to use (I choose 6400), my ISO Sensitivity Setting is sort of my base sensitivity (I choose ISO 100), and the minimum shutter speed is where I want a change in ISO to kick in if it needs to happen. Right? But the exposure bars still activate in the viewfinder and what I don't understand is what ISO that meter is using to determine the exposure. You would almost think it would be on -0- all the time because the ISO would be changing to make a perfect exposure. But that's not the case. I am definitely missing something.