Auto iris is at least not the end of the world if it is dark. I often use it as I have to in surgery, because I can’t often reach the cameras which are on boom arms. I certainly don’t do this when I can have full control of the camera. And if I shoot an open wound case, in which auto iris will flutter and adjust when white surgical gloves come into the scene, I will most certainly use manual iris.
If the footage is dark then take it into FCP and use the 3-way color corrector to raise the exposure level as you would in photoshop. What is unforgiving about digital exposure is when you shot overexposed. And in principle, only underexposed footage can be brightened, but overexposed cannot.
Greg Ondera
http://www.Plexus.tv
http://www.SurgeonToday.org