Binoculars

Binoculars (called Telescopes in Nintendo Power ) are telescopic devices that are commonly used in 3D Super Mario games.

Super Mario 3D Land
Binoculars are introduced in Super Mario 3D Land. If Mario steps on a green platform in front of it, he can look through the lens and get a view of the whole area. The binoculars are controlled by moving the Nintendo 3DS around using its gyro-sensor control and the player can press or  to zoom out and zoom in, respectively. The player can also look for hidden Toads, and if the Toads are sighted, they will throw out items such as Star Medals, 1-Up Mushrooms, or even Super Stars. The camera can also be moved about using the on the 3DS. The image within the binoculars appears as 2D even if 3D is turned on.

Super Mario 3D World
In Super Mario 3D World, a Sprixie holding a pair of orange binoculars appears in certain points of the levels, indicated with a white, round platform. Once the player(s) step on that platform, the camera shifts towards the direction of the Goal Pole, as the Sprixie looks through the binoculars. While these spots are referred to as Binoculars in the game's Prima eGuide, there are differences compared to other games: the player(s) cannot zoom in or out, and can only move the camera angle along a fixed plane.

Super Mario Odyssey
Binoculars return in Super Mario Odyssey. Here, Mario uses them by capturing them with Cappy, and they launch upward a set distance (due to being tethered by a thin cord) before usage, allowing Mario to view more of the area he's in. In some kingdoms, a peculiar flying object (such as the Sphynx or a taxi) can be spotted in the sky, and zooming onto it with the binoculars will make a Power Moon appear.

Super Mario 3D Land

 * North American website bio: "Take a peek into one of these to see far away platforms or possible secret areas."
 * European website bio: "These are to be found dotted around the game's courses. Use them to get a glimpse of the world around you."

Trivia

 * In certain levels in Super Mario 3D Land (such as World 1-3) where the pair of Binoculars are found, the player may be able to spot with them a white UFO that eventually disappears from sight.
 * In the Goomba Spotting minigame in Mario Party 9, the whole minigame seems to have been seen from a pair of binoculars, except at the ending.
 * In Super Mario Odyssey, Binoculars resemble R.O.B.'s head.
 * When looking at the sun through binoculars in Super Mario Odyssey, Cappy will tell either the player or Mario to stop.