How to prevent camera zoom-in?

I am making a map where I want the camera to stay zoomed-out to a higher distance than usual, but the camera should be movable as usual. This works fine, except that if the player uses the mousewheel to zoom in, it ruins the effect.

Is there any way, short of "set camera distance and angle every 0.5 seconds", that I can prevent players from zooming in the camera?

E: Every 0.5 seconds of game time
C: None
A: Set [distance] of [Current Camera] to [away distance]

Bah, Blizzard needs to give us a "Lock Camera Settings" that doesn't send users into Cinematic Mode.

What are you talking about?