Why are there an Objective Lens on some Scopes and for what reason? I always set mine at 00, other times I set mine at 100 yards. Can this give me a relitive idea in knowing the distance of my target? I have no idea how to use this, and I am sure some others are as lost as I am. Can this help me be a better shot by understanding how it works? I have a few Scopes with this lens and I don't know why they are there. Thanks Guys.