The adjustable Objective allows operator to focus at distances over 100 yards and adjust for a condition called Parallax. Parallax occurs when viewing distant targets, and the reticle appears to shift or move. Scopes with adjustable objective lenses have markings that allow you to adjust the focus for specific ranges. This occurs when the image in the scope is in one focal plane, and the reticle is in another. Most scopes without adjustable objectives are factory set to compensate for parallax and focus at an optimum distance of 100 or 150 yards. Parallax is usually only an issue at magnification over 10 power.

The Angle of View is the angle between the left and right edges of the field of view at 1000 yards from the Binoculars' point of view.

The Apparent Angle of View is this same angle with the binoculars' magnification figured in, the Apparent is simply the (magnification x Angle of View).

An optical device, such as a pair of field glasses or opera glasses, designed for simultaneous use by both eyes and consisting of two small telescopes joined with a single focusing device. Binoculars are available with fixed or variable magnifications.

Close Quarters Battle (CQB) or close quarters combat (CQC) is a type of fighting in which small units engage the enemy with personal weapons at very short range, potentially to the point of hand-to-hand combat. In the typical CQB scenario, the attackers try a very fast, violent takeover of a vehicle or structure controlled by the defenders, who usually have no easy way to withdraw. Because enemies, hostages/civilians, and fellow operators can be closely intermingled, CQB demands a rapid assault and a precise application of lethal force. The operators need great proficiency with their weapons, but also the ability to make split-second decisions in order to avoid or limit friendly casualties. CQB is defined as a short-duration, high-intensity conflict, characterized by sudden violence at close range. (Wikipedia Excerpt)