Just turn off Depth of Field. You are not missing much. It's not a realistic effect in ETW. The idea behind it is the camera (or your eye) can only focus on one object at a time. The surrounding area is blurred. Problem is the game has no way of tracking what your eye is focusing on. The way they implement it in ETW, only the center of the screen is clear. This would imply you only ever look near the center of the screen. For a strategy game this is not true at all. Since there's no easy mouse look camera, you can't easily move the camera to focus on what you may want to see. The only good use for Depth of Field is cinematics and shooters where you move the camera in first person with your eyes.