Why larger objective bells????

[Catfish]

I think you ran into a salesman that had no idea what he was talking about. The reason for a larger obj. lens is to gather more lite, and it is not nessary with lower powered scopes. With the lense coatings and quality of some of the glass on the market today the big bells help only with high mag. scopes in very low lite. As for scope haveing a greater varation in magnifaction has nothing to do with the size of the lenses. The varation come from moveing a lense inside the scope back and froth to increase or decrease magnifaction. The problem with varibles is holding that center lens in proper alinement so that you point of impact does no change when you switch power setting on your scope. With todays technoledge they are able to build the tubles nessary to do this more presicely and hence longer giveing you a greater varablity in power.