Topcon DT309LG Digital Theodolite with Laser Pointer
The Topcon DT309LG is a professional-grade digital theodolite built for surveyors and contractors who demand reliable angle measurement in the field. Featuring 9-second angular accuracy and an integrated laser pointer, the DT309LG allows operators to precisely identify and communicate measurement targets across open terrain, dense vegetation, or active job sites—without relying on additional spotters. Whether you're laying out structural columns, establishing property boundaries, or performing control traverses, this instrument delivers the precision and durability that professional fieldwork requires.
Overview and Jobsite Applications
Engineered for both surveying professionals and construction crews, the DT309LG streamlines angle measurement workflows on a wide range of project types. The laser pointer cuts crew coordination time significantly—point the instrument at a target and let the beam do the communicating. The large, backlit dual-face display ensures easy reading in bright sunlight or low-light conditions, while the compact, dust- and splash-resistant body holds up to the demands of daily site use. With battery life rated for hundreds of hours of typical operation, this theodolite is ready for extended fieldwork without constant power management concerns.
Key Specifications
- Model: DT309LG (SKU: 1034419-09)
- Angular Accuracy: 9 seconds (9")
- Display: Dual-face LCD with backlight
- Minimum Reading: 1" / 5" / 10" selectable
- Telescope Magnification: 30x
- Effective Aperture: 45mm
- Field of View: 1°30' (26m/1000m)
- Minimum Focus Distance: 1.0m
- Laser Pointer: Integrated, Class II
- Level Sensitivity (Circular): 10'/2mm
- Level Sensitivity (Plate): 30"/2mm
- Dust & Splash Protection: IP54 rated
- Operating Temperature: -20°C to +50°C (-4°F to +122°F)
- Battery: AA x 4 (approx. 150 hours typical use)
- Weight: Approximately 4.6 kg (with battery)
Key Features
- Integrated Laser Pointer: Quickly identify targets from the instrument position, reducing the need for additional spotters on site
- 9-Second Angular Accuracy: Suitable for boundary surveys, construction layout, and topographic work where repeatable precision is required
- Dual-Face Backlit LCD: Readable from both sides of the instrument in all lighting conditions, including direct sunlight
- Selectable Minimum Reading: Choose 1", 5", or 10" increments to match the precision requirements of each task
- 30x Telescope: High-magnification optics for accurate sighting at extended distances
- IP54 Protection: Dust- and splash-resistant housing built for real-world field conditions
- Long Battery Life: Up to 150 hours of operation on standard AA batteries—no proprietary packs required
- Audible and Visual Leveling Aids: Electronic guide makes setup faster, even for less experienced operators
Job Applications
Property Boundary Surveys: The 9-second accuracy and laser pointer make the DT309LG a dependable choice for legal boundary work, where precise angle measurement and clear target identification are both essential. Surveyors can work efficiently across large parcels without repositioning spotters.
Construction Layout and Stakeout: Set building corners, column lines, and grade stakes with repeatable angular precision. The laser pointer lets the instrument operator communicate exact target positions to rod persons in noisy or spread-out site conditions.
Control Traverse and Traverse Closures: Run traverse loops and calculate closure errors with confidence. The DT309LG's consistent angular performance and easy dual-face reading reduce booking errors and speed up traverse computations.
Topographic and As-Built Surveys: Pair with a separate distance measurement device or EDM attachment to collect topographic data points and verify as-built conditions on civil and infrastructure projects.
Compatible Accessories
- Topcon Aluminum Tripod — Heavy-Duty Field Tripod
- Topcon Tribrach with Optical Plummet
- Surveying Rod and Prism Pole Set
- Topcon Instrument Carrying Case
- AA Battery Pack (Bulk Field Supply)
Related Guides
- How to Set Up and Level a Digital Theodolite on a Job Site
- Digital Theodolite vs. Total Station: Which Do You Need?
- Understanding Angular Accuracy: What Does 9-Second Mean for Your Work?
- Topcon Surveying Instruments — Full Product Line Overview
Frequently Asked Questions
- What is the difference between the DT309LG and the standard DT309?
- The DT309LG includes an integrated laser pointer that the standard DT309 does not. The laser allows the operator to visually indicate the sighted direction to crew members or to quickly locate a target in the field. Both models share the same 9-second angular accuracy and optical specifications.
- Does the DT309LG measure distances?
- No. The DT309LG is a pure digital theodolite designed for angle measurement only. It does not include built-in EDM (electronic distance measurement) functionality. For combined angle and distance measurement in a single instrument, consider a Topcon total station.
- What batteries does the DT309LG use?
- The DT309LG is powered by four standard AA batteries, which are widely available and easy to carry in the field. Under typical usage conditions, a fresh set of batteries provides approximately 150 hours of operation, making extended fieldwork practical without frequent battery changes.
- Is the DT309LG suitable for construction layout work, or is it primarily a surveying instrument?
- The DT309LG is well-suited for both applications. Its 9-second accuracy meets the requirements of most construction layout and stakeout tasks, and the laser pointer is particularly useful on active job sites where communication between the instrument operator and rod persons can be challenging. Professional surveyors also rely on it for boundary and control work.
