Transits, Theodolites, Total Stations, and Levels

This article is to help explain the differences in Transits, Theodolites, Total Stations, and Levels.

Transits
A transit is type of theodolite that features a telescope that can "flip over" which would allow easy back-sighting and doubling of angles for error reduction. Some transit instruments were capable of reading angles directly to thirty arc-seconds. In the last 50 years, transits have been known as a simple form of theodolite with less precision, lacking features such as scale magnification and mechanical meters. The importance of transits has been decreasing since more compact, accurate electronic theodolites have become widespread tools, but transits still find use as a lightweight tool for construction sites. Please note that some transits do not measure vertical angles.

Theodolites
A Theodolite is a instrument for measuring both horizontal and vertical angles, as used in triangulation networks. It is a tool used in the surveying and engineering industry, but theodolites have been adapted for other specialized purposes as well. A theodolite consists of a telescope mounted movably within two perpendicular axes, the horizontal or trunnion axis, and the vertical axis. When the telescope is pointed at a desired object, the angle of each of these axes can be measured with great precision, typically on the scale of arcseconds. The measurements are typically recorded by hand as they are not recorded by a computer or data collector.

Total Stations
A total station is an optical instrument used in modern surveying. It is a combination of an electronic theodolite (transit), an electronic distance measuring device (EDM) and software running on an external computer, such as a laptop or data collector.

Levels
The builder's level is often mistaken for a transit, but is actually a type of inclinometer. It measures neither horizontal nor vertical angles. It simply combines a bubble level and telescope which allows the user to visually establish a level line of sight along a plane.



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