What does the ZoomRate function do? I've tried changing the value, but i don't see any difference.

I believe Dann_Boeing's .odf guide explains it. Look in the .odf section of the FAQ thread for a link to something like "SBF_Dann_Boeing's odfs for dummies."

ZoomRate gives you a different zooming behavior, that is, if you have ZoomMin=10 and ZoomMax=20 you will only get those two while pressing zoom button in-game, if you add ZoomRate=5 for example, you will zoom from 10 in-game but it will increase or decrease while pressing W or S (up and down), that will make your rifle a little more dynamic but your sniper will stand still while aiming.

Thanks. I thought it was something like this, but i used it on a normal scope, and I was wondering why my guy was standing still.