🔭 Newtonian & Dobsonian Collimation

How to Collimate Your Telescope

A complete, step-by-step walkthrough for aligning your Newtonian or Dobsonian reflector — in three layers, from preparation to a precision autocollimator finish.

Home › Collimation Tools › How to Collimate Your Telescope

Every Newtonian needs collimation. They ship imperfectly aligned and slowly drift out of alignment — or “decollimate” — as you move them. A truss-tube Dob needs a tune-up every time you set it back up; a solid-tube scope needs periodic checks. The good news: with the right tools and this guide, it takes only a few minutes, and the jump in image sharpness is immediate.

This guide is organized as three layers. Most observers live in Layers 1–2; Layer 3 is the precision finish for fast imaging scopes and anyone chasing the tightest stars.

The order: Preparation → Two-Tool Collimation (Laser + Cheshire) → Autocollimator. Each layer has a Quick steps track and a Full guide track — same procedure, more reasoning.
1

Layer 1 — Preparation

Center-spot the primary, make the mirror cell hold its adjustment, and position & rotate the secondary. Do this before you collimate.

Start Layer 1 →
2

Layer 2 — Two-Tool Collimation (Laser & Cheshire)

The everyday collimation. The laser sets the focuser axis and ballparks the primary; the Cheshire sets the primary precisely.

Start Layer 2 →
3

Layer 3 — Autocollimator

The precision finish. Refine and verify with the single-pupil autocollimator (iterative and CDP methods), with an interactive eyepiece-view tool.

Start Layer 3 →

Download the Guides

Prefer to read at the eyepiece or print for the field? Grab the PDF guides — a Quick-Start for just the steps, or the Complete Manual with full theory and diagrams.

📄 Download: Quick-Start (Core) PDF📘 Download: Complete Manual (Full) PDF

The Tools You'll Use

This guide is written around the Farpoint two-tool workflow. Each tool handles a different part of the alignment:

Laser Collimators
Laser Collimators
Sets the focuser axis and ballparks the primary — the fast first step.
Shop laser collimators →
Cheshire Eyepieces
Cheshire Eyepieces
Sets the primary precisely. Reflective-pane design, no crosshairs.
Shop Cheshires →
Autocollimators
Autocollimators
The precision finish for fast scopes and astrophotography.
Shop autocollimators →

Collimation FAQ

Do all Newtonian telescopes need collimation?
Yes. Newtonian and Dobsonian reflectors ship slightly out of alignment and drift — or “decollimate” — as they are moved. Keeping the primary and secondary mirrors aligned is the single biggest factor in sharp stars and high-contrast planetary detail.
How often should I collimate my telescope?
Most Newtonians benefit from a quick collimation check before every session, especially after transport. A truss-tube Dobsonian should be checked every time you set it up; a solid-tube scope needs periodic checks. With the two-tool method it takes only a few minutes.
How do I know if my telescope needs collimation?
Tell-tale signs are soft or flared stars, reduced lunar and planetary contrast, and asymmetric diffraction patterns — most visible at high magnification and in fast (low focal-ratio) Newtonians. In practice, assume a Newtonian needs a check; it rarely hurts to verify.
What tools do I need to collimate a Newtonian?
At minimum a laser collimator and a reflective Cheshire, plus a center-marked primary mirror. The laser sets the focuser axis and ballparks the primary; the Cheshire sets the primary precisely. An autocollimator adds a precision finish for fast scopes and astrophotography.
Can I collimate an SCT or refractor with these tools?
No. These procedures and Farpoint collimation tools are for Newtonian and Dobsonian reflectors only. SCTs, Maks, and refractors use different alignment methods.

New to collimation? Start with a kit.

Our kits bundle the two-tool workflow — laser, Cheshire, and center-marking template — so you have everything to follow this guide from step one.

Shop Collimation KitsWhy Collimation Matters

These procedures are for Newtonian and Dobsonian reflecting telescopes. CATSEYE™ is a trademark of CatEye Collimation; Farpoint is not affiliated with CatEye Collimation.