This morning I went out to photograph the sunrise. I left long before dawn, and it's a new moon day, so it was very dark while I was getting ready. I changed the ISO to the maximum setting for composition and focus purposes with aperture in f / 8. The exposure meter recommended a shutter speed of 1 s, which was road too short. I got a discreet but good exposure with a shutter speed of 30 s. This is a difference of approximately 5 stops.
I obtained the same meter readings using the evaluation and average measurement modes.
At this point, I started ignoring the exposure meter and firing a lot of test shots to mark everything (I'm glad I came out so early), but I'm curious why he gave this reading. Once there was enough light to distinguish the characteristics of the landscape with the naked eye, the measurement system began to give healthy results again.
Why did I get such an unstable measurement result in those conditions? Does the camera simply give up and avoid reading in so much darkness?
When I first set up, I was still in open priority mode since my last session. I was just trying to get a starting point, so I pressed halfway in this mode, and suggested 1 s, which I already thought would not be enough. I assumed that maybe there was a built-in limit so that Av mode didn't give a slower shutter speed than that, so I switched to manual immediately. But even then, the exposure meter was reading about 0 with a shutter speed of 1 s, and off the bright end of the scale at 30 s, which gave a good image.