EOS 5D Mark IV: Exposure Simulation

Shooting in Live View on many EOS cameras allows you to see what the image will look like before you press the shutter button. This is very useful for situations where the camera is on a tripod, for example when shooting landscapes. If you are looking at the Live View screen and the Exp.SIM icon and the histogram are in grey, then you are not seeing the true brightness setting. This is because you are either shooting in BULB mode or with flash, or you have set Multi Shot Noise Reduction or HDR mode. In these cases, the image displayed will be at the ‘average’ brightness. In these situations you will need to rely on the exposure scale to help judge your exposure.
Camera settings
EOS 5D Mark IV