A range finder is a device that allows its operator to measure a distance via optical means, rather than using tools like tape measures or trundle wheels, or predetermined distances between landmarks. There are various ways to find ranges in this manner:
- Devices such as macrometers allow the user to compute the range by aligning two images and measuring its offset.
- Stadiametric range finders measure the image height of a known object. These may appear in scopes, allowing a shooter to estimate range given a soldier's average height of 1.7 meters.
- Telephoto lenses can be used for ranging by precisely focusing on the target and reading the lens markings.
- A laser range finder emits coded pulses of light and measures the offset from the reflected beam.
The range finder displays the range to the spot targeted by the weapon's crosshairs, and the current zeroing of the attached scope, on its integrated display screen. When aiming down sight, the range and zeroing also appear imprinted in the scope view.
The PLD and XM25, as well as FLIR and IRNV sights, also include built-in rangefinding. A Recon player can make use of the PLD to acquire target distance, useful if they do not have a rangefinder on their rifle.