The goal is regard to the object in itself, regardless of how to think or feel. For example: someone weighs a case on a balance and says that its weight is five kilos. This information is objective, the opinion of the subject having no influence since it is determined by the laws of physics. On the other hand, if someone else raises the Fund and said that it is very heavy, it is a subjective information (it rather depends what the subject consider and not the object in itself: that same body can be light as a feather for someone else).
That adjective, the term objective a person with no interest and whose opinion is unbiased ("because I do not part of the team, I can be objective.") If you want to know my opinion, I find that the coach had an incorrect attitude") or what really exists ("that it you like it or not, it is an objective question. It will put me at the door in three days unless we forgive my debt").
Objective is also a noun. A goal is a point or an area of land to fight fire with a shot or a bombardment ("one who happens to cross the goal to more than fifty meter of distance have the right to a reward") or conquer by the movement / attack ("my General, we hit the goal. The enemy aircraft was shot").
In optics, it is a system consisting of lenses that, once turned on the side of the object you want to observe, is used to form images in shooting (with a camera or a microscope, for example).