Alignment eyepiece for Newtonians and refractors - Cheshire 1.25" eyepiece
Allows perfect adjustment of telescopes and Newtonian refractors
The Cheshire eyepiece is the classic adjustment tool for Newtonians and refractors. Light is directed into the beam path by a mirror-polished aluminum insert. The collimation can be checked through an inspection opening. A cross is also attached to the telescope end of the Cheshire eyepiece.
The Cheire eyepiece has a very wide stop edge. As a result, an exact stop is always defined, even with slightly larger 1.25" focusers.
Newton's Mirror Telescopes: With a properly adjusted telescope, you will see the crosshair, the center mark of the primary mirror, and the reflected image of the secondary mirror placed concentrically on top of each other. Fit errors are expressed as a displacement of these elements relative to each other.
Refractors: With a refractor, you get an image that ideally shows several concentrically arranged rings. The number of these rings depends on the type of lens. If the rings are not concentric but offset against each other, the telescope needs to be adjusted.
TS Handy Tip
When adjusting the refractors, the eyepiece should always be straight, ie it should never be used with a diagonal mirror, because the mirror itself can also introduce inaccuracies into the system. When adjusting Newtonian telescopes, the adjustment eyepiece should not be clamped, but rather be inserted unclamped into the focuser with the tube horizontal and the focuser pointing vertically upwards.
Collimation line as PDF file
Teleskop-Service has created collimation instructions:
♦Collimation instructions for Newtonian telescopes.