Binoculars

Select them in the hotbar and the camera slides partway toward your cursor, settling near the midpoint between you and the pointer. You can scout a cave mouth, a floating island or an incoming event from a standstill. Push the view far enough into a neighboring biome and the music and background switch to match, and the minimap fills in whatever the camera passes over.

Spawn distance is measured from the camera while the item is held, so enemies appear further out and the area you are standing in goes still. That is genuinely useful when you want to place blocks in an unlit area without a fight starting. It only applies while you are actually holding them: hovering the cursor over an inventory slot cancels the effect the same way it cancels a controlled projectile.

Pushing spawn range out has a cost. Switch away from the Binoculars and you will sometimes watch enemies vanish as the camera slides home, which is fine when you are clearing a path and infuriating when you were lining up something rare. With autopause on, opening the inventory locks the shifted view where it is instead of snapping it back, which is the reliable way to study a distant screen.

Paired with a Lifeform Analyzer, this is how you actually locate the rare enemy it is announcing instead of blundering into it. The other trick is projectile steering: fire a Magic Missile or Rainbow Rod, keep the button held, swap to the Binoculars, and you can drag the camera along with the projectile, pushing its usable range well past normal.

Five things in the game move the camera. The other four are the Rifle Scope, Sniper Scope, Recon Scope and the Sniper Rifle itself, all bound to guns and all hardmode. The Binoculars are the only pre-hardmode option and the only one that does not ask you to be a gunner, which is why they are worth farming the Eye of Cthulhu for on a fresh world.