What Is the Difference Between a Transit & Optical Level?

Surveyors are often seen in the middle of fields or on the sides of the road. One person usually stands looking through a camera-like object, while another stands a certain distance away, holding a stick. To the innocent bystander, this process may seem nonsensical. To surveyors and others looking to determine land elevations, the process is vital to the building process.

Both optical and transit levels are field instruments used to measure land elevations. They are essentially telescopes that allow surveyors and builders the opportunity make the measurements. The transit level is simply a more advanced instrument than the optical level and can perform tasks beyond measuring land elevations.

Optical and transit levels are the alternative for using measuring tape and a hand level over large distances. According to professional builder Tim Carter of the Ask the Builder website, both transit and optical levels are used to find the difference between elevations. Only the transit level, however, can turn onto its side and make the same measurements vertically. The feature is used to measure vertical angles and distance between parallel objects. The transit level is also most likely to have the 360-degree measurements along the base to allow a swivel in the middle of the line. A transit level can establish a perfect level line, something that can't be done with an optical level.

According to the International Rice Research Institute, an optical level is the preferred instrument for farmers wanting to measure their farmland elevations. The simplicity of the optical level allows surveyors in agriculture to get the job done without the unnecessary options that they probably will never use. Transit levels, however, are more compatible with the many measurements required in construction and architecture. The complex measurements needed to plot a building, from the land development to final construction are easily taken with the transit level.

The levels are set up on a tripod and operated according to the instructions that came with the device. In the viewfinder, a line is seen that can be manipulated to adjust to a point on the stick being held by the second surveyor. The stick is called a grade pole. More than one point is measured to get information