Overview
The Sokkia DT240 Digital Theodolite delivers 2 arc second angular accuracy—the precision threshold required for licensed boundary surveys, control network densification, geodetic observation, and critical industrial alignment. Licensed surveyors use this instrument when angular measurements must satisfy state surveying standards or when establishing primary control that cascades through entire project sites. Civil contractors deploy the DT240 for high-rise plumb verification, bridge pier alignment, tunnel heading control, and machinery installation where angular tolerances dictate millimeter-level positional accuracy over extended distances. This complete kit includes the theodolite, protective carrying case, optical plummet, and all necessary tools for immediate deployment—eliminating the need to source accessories separately before fieldwork begins.
Key Specifications
- Angle Measurement Accuracy: 2 arc seconds (horizontal and vertical)
- Display Configuration: Dual-sided independent LCD displays for instrument operator and assistant viewing
- Telescope Magnification: 30× with 45mm objective diameter
- Minimum Focusing Distance: 0.9m (3.0 feet) for close-range applications
- Compensator Range: ±3 arcminutes with automatic vertical index correction
- Environmental Protection: IP66 rating (dust-tight, protected against heavy seas and powerful water jets)
- Operating Temperature: -20°C to +50°C (-4°F to 122°F)
- Power System: Rechargeable NiMH battery with 11-hour continuous operation
- Instrument Weight: 5.0kg (11.0 lbs) without battery or tribrach
- Data Storage: 10,000 point internal memory with RS-232C output
What's in the Kit
- DT240 Theodolite Body – Dual-display instrument with absolute encoders and compensator
- Rechargeable NiMH Battery Pack – Field-replaceable power module with 11-hour runtime
- Battery Charger with AC Adapter – Universal input voltage (100-240V) for international use
- Optical Plummet – 3× magnification downward-viewing centering telescope integrated in tribrach
- Tool Kit – Adjustment tools, brush, and lens cloth for field maintenance
- Hard-Shell Carrying Case – Impact-resistant protective housing with custom foam insert
- Rain Cover – Transparent weather shield for operation in precipitation
- Instruction Manual – Complete operation, adjustment, and specification documentation
- USB Cable and Data Transfer Software – For downloading stored measurements to PC
Job Applications
- Boundary and ALTA/NSPS Land Surveys – 2" accuracy satisfies state minimum standards for property corners and meets ALTA accuracy requirements for commercial real estate surveys.
- Control Network Establishment – Provides the angular precision necessary for traverse closures and control densification where positions feed GPS post-processing or serve as project datum.
- High-Rise Plumbness Verification – Measures vertical deviation of building cores, elevator shafts, and structural columns during construction to ensure architectural tolerances are maintained.
- Bridge Construction Alignment – Controls pier placement, bearing alignment, and deck geometry where horizontal and vertical angle precision directly impacts structural load distribution.
- Industrial Equipment Installation – Aligns turbines, conveyors, cranes, and processing equipment where operational efficiency and safety depend on precise angular relationships between components.
- Tunnel and Mining Heading Control – Establishes alignment through bore operations where angular error compounds over distance and breakthrough tolerances are contractually specified.
- Monitoring and Deformation Surveys – Establishes baseline measurements and detects angular displacement in structures, slopes, and retaining walls through repeated observations.
Compatible Accessories
Tripods: Sokkia Heavy-Duty Aluminum Tripod | Sokkia Wide-Frame Wood Tripod
Targets and Prisms: Sokkia 360° Prism System | SECO 8-Foot GPS Rover Rod with Adjustable Prism Mount
Power Solutions: Sokkia Spare NiMH Battery Pack | Dual-Bay Rapid Battery Charger
Data Collectors: Sokkia SHC5000 Field Controller | Carlson Surveyor 2 Data Collector with SurvCE
Related Guides
Theodolite vs. Total Station: When Angular Measurement Without EDM Is the Right Choice
Sokkia Digital Theodolite Comparison: DT540 vs. DT740 vs. DT940 Accuracy Classes
Troubleshooting Theodolite Compensator Out-of-Range Errors and Calibration Procedures
Frequently Asked Questions
- What's the practical difference between 2 arc second and 5 arc second theodolite accuracy for boundary surveys?
- At 100 feet, 2 arc second accuracy produces ±0.001 feet of perpendicular error, while 5 arc second accuracy produces ±0.0024 feet. For most boundary surveys, this difference is negligible and both satisfy state minimum standards. However, 2 arc second instruments are preferred for control networks, long-sight observations exceeding 500 feet, and ALTA surveys where the additional precision provides measurable improvement in closure accuracy and supports tighter error budgets for commercial certification.
- Can the DT240 replace a total station for construction layout work?
- The DT240 measures angles only—it does not have an integrated electronic distance meter (EDM). You can perform layout using angle intersections, or by pairing the theodolite with a separate tape or laser distance meter, but this workflow is significantly slower than using a reflectorless total station with coordinate stakeout software. The DT240 is the right choice when you need precise angles for alignment, monitoring, or observation work where distances are measured separately or derived mathematically.
- How does the dual display function improve field productivity?
- Both sides of the DT240 have independent LCD displays showing horizontal angle, vertical angle, and measurement mode. When working in two-person crews, the instrument operator and assistant can simultaneously view angle readouts without requiring verbal communication or repositioning. This configuration speeds repetitive observation tasks such as monitoring rounds, angle averaging, and turning multiple positions—particularly beneficial for survey crews running traditional traverse or when training less-experienced rod holders who need to confirm backsight and foresight angles independently.
- What maintenance intervals does Sokkia recommend for the DT240 compensator and optical system?
- Sokkia recommends annual factory calibration for instruments in daily professional use, or every two years for occasional-use applications. The automatic compensator should be checked monthly using the compensator test function in the instrument menu, and field-adjusted if readings drift beyond ±3 arc seconds. Optical collimation should be verified quarterly using the two-peg test method, with adjustments performed by certified technicians if collimation error exceeds 10 arc seconds. The instrument should return to a Sokkia service center if subjected to hard shock, submersion, or if angle measurements show unexplained inconsistency between face-left and face-right observations.
