parts of the scene are in focus which helps with focussing and composing a shot) and zebras (which help with setting exposure by indicating on screen when a part of the image will be overexposed with the current camera settings). The digital preview shown in an EVF incorporates the camera's settings (including exposure, white balance, etc.) and so the image seen can be an exact preview of what the taken photograph will look like, which is not possible with an OVF.

OVFs may be better suited to