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Skywatcher Cheshire Collimating Eyepiece 20930

  • This provides an exact alignment of the Cheshire so that the collimation result will be accurate even if there is play between the Cheshire and the focuser.

  • For Newtonian telescopes: Insert the Cheshire like a normal eyepiece into the telescope focuser. Turn the porthole on the side towards a light source and look into the pinhole of the eyepiece. Once the crosshair and the reflection of the secondary mirror are concentric the telescope is properly collimated.

  • For Refractors: When looking through the Cheshire you will see as many reflected discs as there are glass-to-air surfaces. (Example: An air-spaced doublet refractor will show four reflected discs, of which usually two are brighter.) Once all these rings are concentric the telescope is perfectly collimated.

  • Fully metal construction.

  • Compliable with Newtonian telescopes and Refractors.

SKU: 6930096631519
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This collimating eyepiece is a combination of a sighting tube and Cheshire eyepiece. The sighting tube’s narrow field of view and crosshairs provide a centering reference for the telescope’s optical elements. The Cheshire eyepiece has a means of providing illumination to a target face (set at 45 degrees to the illuminating hole) that will be used to collimate the primary mirror. 

Additional Information

Manufacturer Part Number 20930
Condition New
Weight (grams) 300.0000