Telrad finder

Telrad finder

Description

The Telrad finder is a straight-through, non-magnifying astronomical sight designed to simplify telescope pointing. Its operating principle is based on projecting a reticle composed of three concentric rings onto a glass plate inclined at 45°, superimposing the target directly onto the naked-eye view of the sky. The absence of lenses eliminates any image inversion found in conventional optical finders.

The projected rings correspond to precise angular fields of 4°, 2° and 0.5°, enabling rapid centering of known objects or accurate star hopping using celestial charts such as Sky Atlas 2000.0 or Uranometria. Once properly aligned with the optical tube, the target object appears directly in the field of view of a medium focal length eyepiece.

Calibration is achieved using three spring-loaded push-pull adjustment screws acting on an internal reflective mirror, allowing fine and stable alignment. Reticle brightness is adjustable via a side-mounted control knob connected to a potentiometer, with an off position to prevent battery drain.

The Telrad consists of a fixed mounting base attached to the optical tube and a removable finder unit that can be quickly installed or removed. The rounded base is designed to fit telescopes with diameters of 150 mm and above, including Newtonian, Cassegrain and Dobson designs. The reticle remains visible regardless of observer distance, making it suitable for eyeglass wearers and very large telescopes. Power is supplied by two LR6 batteries not included. The finder is delivered in a foam-lined cardboard storage box.

Technical specifications

• Type: non-magnifying astronomical finder

• Magnification: 1x

• Viewing mode: straight-through

• Projection: illuminated reticle on 45° glass plate

• Reticle rings: 4°, 2°, 0.5°

• Image inversion: none

• Brightness control: adjustable with off position

• Calibration: three spring-loaded push-pull screws

• Mounting: adhesive base with removable finder

• Compatibility: telescopes 150 mm diameter and larger

• Telescope types: Newtonian, Cassegrain, Dobson

• Power supply: 2 LR6 batteries not included

• Reticle visibility: independent of observer distance

• Packaging: cardboard box with pre-cut foam