Binoculars were a device used by Humans and other species. They had small identical mirrors inside them, which allowed a person to view distant objects with both eyes.
On Earth in 1986, the lookout stationed in the crow's nest aboard a Scandinavian whaling ship was using binoculars when he spotted George and Gracie. His captain also had a pair of binoculars, which were supported by a wooden beam, and he used it to confirm the sighting. (Star Trek IV: The Voyage Home)
In 2152, Korok used a pair of 22nd century Klingon binoculars. He looked through them to see that multiple colonists were hiding from him and his Klingon marauders. (ENT: "Marauders")
The next year, Human Starfleet Captain Jonathan Archer and Lieutenant Malcolm Reed used a pair of binoculars to spy on a Xindi-Arboreal colony. (ENT: "The Shipment")
In the final draft script of "The Shipment", these binoculars were described as "a pair of compact Starfleet binoculars".
James T. Kirk and Spock used 23rd century versions of binoculars while on Nimbus III after landing far from Paradise City. Earlier, Leonard McCoy used the same binoculars to view Kirk climbing El Capitan. (Star Trek V: The Final Frontier)
Geordi La Forge's VISOR functioned much like binoculars in some cases. (TNG: "Hide and Q")
In 2372, Major Kira Nerys equipped herself with Bajoran binoculars during a mission to locate crashed Cardassian freighter Ravinok, which had been carrying Bajoran prisoners. Kira used the binoculars to look at the Ravinok survivors at a labor camp overseen by the Breen. (DS9: "Indiscretion")
In 2375, Captain Jean-Luc Picard viewed the mountains on the Ba'ku planet through binoculars with Anij while looking for suitable locations to hide from the Son'a. (Star Trek: Insurrection)
Later that year, Lieutenant Nadia Larkin and Reese used binoculars to locate Jem'Hadar soldiers, on AR-558, that were planning to attack the Starfleet forces who were protecting a Dominion communications array. (DS9: "The Siege of AR-558")