Stadiametric rangefinding

Stadiametric rangefinding is used for surveying and in the telescopic sights of firearms, artillery pieces, or tank guns, as well as some binoculars and other optics.

It is still widely used in long-range military sniping, but in many professional applications it is being replaced with microwave, infrared, or laser rangefinding methods.

greatly simplify the trigonometry, enabling one to scale objects measured in milliradians through a telescope by a factor of 1000 for distance or height.

The stadia rod has measurements written on it that can be read through the telescope of the instrument, providing a known remote height for the distance calculations.

If the instrument line of sight is inclined relative to the staff, the horizontal and vertical distance components must be determined.

This system is sufficiently precise for locating topographic details such as rivers, bridges, buildings, and roads when an accuracy of 1/500 (0.2%, 2000ppm) is acceptable.

Table for range estimation showing target sizes, distances and corresponding angular measurements. Angular sizes are given in milliradians (mil), ranges in meters, and target sizes are shown in both in centimeters, millimeters and inches.
Targeting reticle of the M67 recoilless rifle , correctly ranging a tank at 275 m range. Antitank weapons of the 1940–70s used stadiametric range estimation based on the average sizes of armoured fighting vehicles