Telescope

Telescopes were devices for looking at things from a distance.

The Third Doctor carried a folding telescope. On Solos, he used it to survey a Solonian village. (DW: The Mutants)

In the late 15th century, Giuliano developed a primitive telescope, which the Fourth Doctor deemed merely adequate. (DW: The Masque of Mandragora)

In the early 17th century, Galileo Galilei invented the telescope. (MA: The Empire of Glass)

The people of Sarn used telescopes. (DW: Planet of Fire)

In the 19th century, Robert MacLeish and Albert designed a device that others supposed was a telescope. It was in fact a light chamber. (DW: Tooth and Claw)

Richard Dunbar told the Fourth Doctor that if he had seen anything like the Krynoid pod before, he must have a very powerful telescope. (DW: The Seeds of Doom)

Jerome Weismuller used a folding telescope to watch for a satellite. (DW: Delta and the Bannermen)

Eugene Jones used a telescope to watch for aliens. (TW: Random Shoes)

Wilfred Mott had a telescope, which he frequently used. (DW: Partners in Crime) In an alternate timeline, he offered to sell it for extra money, but Donna Noble was firmly against it. (DW: Turn Left)

The Fourth Doctor used a telescope to locate the Jagaroth ship in Earth's primordial past. (DW: City of Death)

The Fourth Doctor later used the same telescope to observe the spaceship Hydrax from afar. (DW: State of Decay)

On Kirith, the Seventh Doctor used a telescope to survey Kirith town and its environs. He then gave the telescope to Miríl. (NA: Timewyrm: Apocalypse)