SECO 2152-04 Optical Plummet Twist Focus Tribrach

Overview

The SECO 2152-04 Optical Plummet Twist Focus Tribrach is a precision instrument-mounting base designed for surveying applications requiring optical centering and reliable leveling.

Its optical plummet features twist focusing, 2.5× magnification, and a focusing range from 1.5 to 50 feet (0.5 to 15 meters). The tribrach also includes leveling screws with center lines, an 8-minute circular vial, and a three-prong forced-centering system.

A standard 5/8-11 base provides compatibility with appropriate surveying tripods and mounting equipment. The SECO 2152-04 is available in Gray, Yellow, and Black.

Key Features

• Optical plummet surveying tribrach
• SECO product series: 2152-04
• Twist-focus optical plummet
• 2.5× optical magnification
• Focusing range from 1.5 to 50 ft
• Metric focusing range from 0.5 to 15 m
• Leveling screws with center lines
• Integrated 8-minute vial
• Three-prong forced-centering system
• Standard 5/8-11 base
• Available in Gray, Yellow, and Black
• Designed for precision instrument setup and centering
• Tripod and surveying instrument are sold separately

Twist-Focus Optical Plummet

The built-in optical plummet uses a twist-focus mechanism that allows the operator to sharpen the view of the survey point below the tribrach.

Its 2.5× magnification provides a clear view for positioning a compatible surveying instrument over a control point, monument, nail, stake, or other field reference.

1.5-to-50-Foot Focusing Range

The optical plummet has a specified focusing range of:

• 1.5 to 50 ft
• 0.5 to 15 m

This broad range supports centering over points at different distances beneath the tribrach, depending on the tripod height and field setup.

Three-Prong Forced Centering

The SECO 2152-04 features a three-prong forced-centering system.

Forced centering allows a compatible instrument or accessory to be removed and reinstalled in a repeatable position without requiring the complete tripod setup to be recentered each time.

This is useful when exchanging compatible instruments, prisms, targets, or other tribrach-mounted equipment over the same survey point.

Leveling Screws with Center Lines

The tribrach includes three leveling screws with center-line markings.

These reference lines help the operator identify the approximate centered position of each leveling screw during setup. Beginning near the center of the adjustment range leaves room for leveling corrections in either direction.

Integrated 8-Minute Vial

An 8-minute circular vial provides a visual reference for preliminary leveling.

The vial helps the operator bring the tribrach close to level before completing finer instrument-leveling adjustments. The vial should be checked periodically and adjusted when necessary to maintain reliable setup performance.

Standard 5/8-11 Base

The tribrach includes a standard 5/8-11 base for mounting to compatible surveying tripods and support equipment.

This common survey-instrument connection allows the tribrach to be used with appropriately threaded tripods and mounting accessories.

Always verify the instrument, tripod, and tribrach interfaces before use.

Available Colors and Part Numbers

The SECO 2152-04 Optical Plummet Twist Focus Tribrach is available in three colors:

• 2152-04-GRY – Gray
• 2152-04-YEL – Yellow
• 2152-04-BLK – Black

Select the preferred color and corresponding part number before ordering.

Ideal Applications

• Total station setup
• Theodolite setup
• Survey instrument centering
• Control-point occupation
• Construction layout
• Boundary surveying
• Topographic surveying
• Monitoring surveys
• Engineering fieldwork
• Forced-centering survey systems

Technical Specifications

What’s Included

• 1 × SECO Optical Plummet Twist Focus Tribrach
• Selected color and corresponding part number

Available configurations:

• SECO p/n: 2152-04-GRY – Gray
• SECO p/n: 2152-04-YEL – Yellow
• SECO p/n: 2152-04-BLK – Black

Surveying instruments, tripods, adapters, prism assemblies, and other accessories are sold separately.

Precision Centering for Survey Instruments

The SECO 2152-04 combines a 2.5× twist-focus optical plummet, broad focusing range, three-prong forced centering, and an 8-minute vial. Its standard 5/8-11 base and three color options make it a versatile tribrach for professional surveying and construction layout.