After trying this (from Sony support) "I will recommend you to power cycle the camera to reset the circuitry of the whole unit. To power cycle, please remove the battery of the camera and turn the power switch to on. After that, please press the shutter button for 1 minute. After power cycle, turn the power switch to off then reinsert the battery then try to test again the camera." nothing changed, so I did some more tests and discovered these behavior:
At 30" shutter speed, Live View Display doesn't brighten up after setting ISO higher than 80.
At 10" shutter speed, Live View Display doesn't brighten up after setting ISO higher than 250.
At 1" shutter speed, Live View Display doesn't brighten up after setting ISO higher than 2500.
At 1/3 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 8000.
At 1/5 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 12800.
At 1/30 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 80000.
At 1/60 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 160000.
At 1/80 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 204800.
At 1/100 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 256000.
At 1/125 shutter speed, Live View Display doesn't brighten up after setting ISO higher than 320000.
But, At 1/8000 shutter speed, I can go all the way down to 50 ISO and see the exposure lowering on Live View Display.
The shutter speed value and ISO value distance is limited to 17 stops upwards. (This affects only the display, the photos are correctly exposed. (eg. 10" SS & 320000 ISO exposes correctly))
Can anyone with a A7S confirm the same (or different) behavior? I wonder if mine needs service.