Auto Levels
Auto Level - FAQ
What is the difference between an auto level and a digital level?
What accuracy does an auto level achieve?
Can an auto level be used without a tripod?
Auto Level - Optical Levelling Instruments for Surveying
An auto level is a specialized optical instrument that utilizes an internal compensator mechanism to automatically maintain a horizontal line of sight once the device is roughly leveled. This tool provides a primary technical advantage in its simplicity and speed of setup, offering a more cost-effective alternative for height transfers than electronic digital levels. While digital models automate data storage, the auto level remains a staple in construction for its reliability in diverse environmental conditions without the need for complex digital interfaces.
Key Features & Specifications
Accuracy: Standard deviation for double-run levelling ranges from $1.0-3.0~mm/km$.
Compensator: Features magnetic damping with a setting range of $\pm15$ arcminutes and an accuracy of $\pm0.5$ arcseconds.
Telescope magnification: High-clarity optics with $20\times$ to $32\times$ magnification power.
Focusing: Shortest focusing distance between 0.3 m and 0.5 m for work in confined spaces.
Stadia measurement: Integrated 1:100 stadia ratio for calculating horizontal distances directly from staff readings.
Weight: Portable design weighing between 1.5 kg and 2.2 kg, representing the lightest class of optical levelling instruments.
Durability: IP54 rating ensuring the housing is dust-sealed and splash-resistant for rugged site use.
How to Choose the Right Auto Level
To choose the correct instrument, you must match the accuracy class to your specific project requirements, such as selecting a geodetic-grade model for precision subsidence monitoring or a standard unit for general site grading. For reliable daily use on construction sites, the Topcon AT-B4A is a frequent choice due to its balance of $2.0~mm/km$ accuracy and robust environmental sealing. Professionals should also consider telescope magnification; while a $24\times$ lens like the Sokkia B40A is sufficient for short distances, a $32\times$ model is required for clearer readings on long-range sightings.