Binoculars

The UNSC type 20 3x scope Binoculars are used in combat to observe and retrieve data against the Covenant and other enemies. Spartans have a slightly more powerful pair built into their visor to allow maximum balance in combat. The Master Chief's Binoculars are a 3-4x scope set, able to locate enemies from over a mile away. The Binoculars range is like that of a Sniper Rifle, only it does not reach 8x zoom.

Efficiency
The Binoculars range is most efficient when used in combat, as it is able to tell UNSC troops where enemies are located or hiding. In Halo: Combat Evolved, Master Chief's Mark V armour did not have built in Binoculars to tell him were the enemies were. The only way he could see was with any weapon that zoomed in. In Halo 2, the UNSC gave Master Chief new armour and built in a pair of Binoculars for the Chief. This proved to be VERY useful, as he needed to defend Earth from a lot of enemies. It is a feature in Halo 3.

UNSC Use
The UNSC troops, without the advanced armor of the Spartans, were only able to carry the type 10 3x scope Binoculars. Carried by troops scanning the environment for any Covenant and Covenant vehicles, they stayed put, to keep them out of sight. Built with a stand to keep the Binoculars steady, they were able to detect Covenant and possibly a Scarab, in the level Outskirts. The binoculars are carried in a pouch on the Marine's side. It has been seen used by a Marine next to a sniper, possible used in sniper-spotter team.

Halo 2
On the level Outskirts, there is a pair of binoculars up on the roof, along with the Blind Skull and four grenades.

Halo 3
The Binoculars featured in Halo 3 have a radius of that of the one's in Halo 2. The only difference is that it shows distance and height. They are more powerful, and are able to not reflect light off the lenses. The Spartans upgraded their Binoculars to this type.

Trivia

 * They are seen in the pre-Outskirts cutscene.
 * Binoculars are also located on the level Metropolis, when the Scarab destroys the Tank. They are on the ledge with the Machine Gun.