#5. "RE: Aperture/Shutter Priority and EV" In response to In response to 4 Fri 14-Sep-12 12:18 PM by briantilley
Using Aperture Priority, when you change the aperture the camera will adjust the shutter speed to keep the same exposure value - as long are you're not limited by the fastest or slowest available speed, neither the meter nor the histogram will move. Adding +ve Exposure Compensation in this situation will push the histogram to the right.
Using Manual exposure mode, the meter and the histogram will move when you vary the aperture or the shutter speed, because by changing either (or both) you are altering the exposure value.