Telrad

The Telrad Finder is a reflex sight, which is used in astronomy to align a telescope at a star.

Three concentric target circles are projected by LED and optics from the bottom of an oriented at a 45 ° angle glass. Looking from the rear by the inclined disc, the luminous image is seemingly be reflected at infinity; therefore, a refocusing of the eye is not necessary. The circles appear, regardless of the distance of the viewer, with a diameter of 0.5 °, 2 ° and 4 ° in the sky, which is very accurate for finding an object. The Telrad finder is however prone to dew. A dew, which also contains a mirror for a 90 ° viewing zenith for near objects is optional.

In the elongated box below before the glass plate there is a battery holder for two AA batteries (Mignon ), the LED including optics and a mirror.

In the picture showing the narrow side of the Telrad viewfinder, you can see above, the reflected- target circles, below it and a lens on the front of the case three adjustment screws, which allow the precise adjustment of the target crosses on the object in the sky. On the right side you can see the power switch, with which you can also adjust the brightness of the target circuits.

The Telrad finder is glued by means of a removable bracket on the telescope tube (two holes also allow unscrewing ).

The dimensions are: 21.5 cm (length ), 12 cm (height without mounting plate ) and 7 cm (width incl switch)

The device was developed in the 1970s in the USA by Steve Kufeld. This was based on a target device for aircraft from the Second World War.

Telrad finder charts

• Finder charts for the Messier Objects (PDF document)

• Optical Telescope Technology
• Amateur Astronomy