The best advice I can give you is buy some from somebody that will refund your money if you aren't happy. I know Doug and Cameraland and Cabela's will do this as I have done it with both.
Compare what you buy yourself, especially from field positions and at the distances you will be using them. Inside a store or in a parking lot is not the same as trying to see something in the high country at 1-3 miles. E
