Sometimes I just don't understand my camera's logic. I have it set on manual; max iso 400. The shot below was taken in very bright sun at 1/640, but the camera thought it necessary to push the iso to the max, so it is way over-exposed. I pp'd the light levels, so it barely passable.
This next shot was taken about 3 seconds later -- same bird, same speed, but now it is at iso 100 and the exposure is good.
I am going to turn off variable iso and use fixed -- I just can't trust or predict what the hell I'm going to get.