Just picked up this scope (New in the Box) and would like to know more about It. It's a 6-24x40mm, Bausch & Lomb, BALVAR by; Bushnell. Seems like an older scope, but the box has a bar code and is made in Japan. Any info would be nice. Also, it has Parallax adjustment. Never heard of this. Is this something I need to worry about? thanks