Overview: The ETH-300 series of electronic theodolites by Pentax are designed for building and construction applications. These compact and portable devices are built for ease of use on construction sites, featuring an easy-to-read display and robust construction.

Models and Accuracy: The series includes four models: ETH-302, ETH-305, ETH-310, and ETH-320, offering angle accuracies of 2”, 5”, 10”, and 20” respectively. These models are suitable for tasks such as setting out right angles, checking plumb, alignment measurements, and anchor bolt layout.

Key Features: The theodolites feature a 16-character x 2-line LCD display on both sides, displaying angles in degrees or gon. They are powered by alkaline batteries and include features like zero set, reverse angle display, and automatic power-off to conserve battery life.

Technical Specifications: The telescope offers 30x magnification with a 45 mm objective aperture and a field of view of 1°30’. The minimum focusing distance is 1.35 m. The devices have a stadia ratio of 100 and a stadia constant of 0. Angle measurement is incremental with a dual reading system for horizontal angles and a single system for vertical angles.

Additional Features: The ETH-300 series includes a vertical axis compensator (except for some models), water resistance rated at IPX 4, and a warning buzzer. The optical plummet has a magnification of 3x. The power source consists of 4 AA dry batteries, providing up to 30 hours of operation with alkaline batteries.

Design and Usability: The instruments are lightweight, weighing 4.6 kg, and include an automatic power-off function. They feature bright optics for clear images even in poor lighting conditions. The standard configuration includes battery cases, adjusting pins, a screwdriver, a plumb bob, a rain cover, and a carrying case.

Contact Information: Pentax provides contact details for their offices in Japan, Europe, and the UK, along with authorized dealer information.