IS 2974:1973 Part 2 is the Indian Standard (BIS) for surveying instruments - part 2: theodolites. This code of practice outlines the general requirements, optical specifications, and testing methods for theodolites used in land surveying. It establishes guidelines for graduation accuracy, magnification, and proper calibration to ensure reliable angular measurements in the field.
Lays down general and specific requirements for various types of theodolites used in surveying.
Overview
- Status
- Current
- Usage level
- Specialized
- Domain
- Geotechnical — Surveying and Geotechnical Investigation
- Type
- Code of Practice
Also on InfraLens for IS 2974
Practical Notes
! Always ensure parallax is completely eliminated by accurately focusing the crosshairs before taking field readings.
! Perform routine checks for vertical index error and horizontal collimation error, especially after long transit.
! Store the instrument in a dry, shock-resistant case to preserve optical alignment and protect from moisture.
Frequently referenced clauses
optical glassaluminumbrass
International Equivalents
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International Comparison — Coming Soon
We're adding equivalent international standards for this code.
Key Values3
Quick Reference Values
magnification range20x to 30x minimum for standard surveys
plate level sensitivity20 to 60 seconds per 2 mm run
operating temperature-20°C to +50°C
Tables & Referenced Sections
Key Clauses
General Requirements for Surveying Instruments
Optical System and Magnification
Graduation of Circles
Testing and Calibration Procedures
Frequently Asked Questions3
What is the typical sensitivity required for the plate level?+
The plate level sensitivity typically ranges from 20 to 60 seconds per 2 mm division depending on the instrument class.
How should observational errors like index error be mitigated?+
By taking observations on both Face-Left and Face-Right and averaging the readings.
What is the recommended minimum magnification for a standard theodolite?+
A minimum of 20x magnification is generally recommended for standard surveying tasks.
QA/QC Inspection Templates
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QA/QC templates coming soon for this code.