A laser is fast, works alone in the dark, and depends on being aimed exactly along its own barrel. A Cheshire uses no electronics, cannot drift, and needs light. Many experienced owners keep one of each and use the second to check the first.
Both tools do the same job by different means, and their failure modes are what separate them.
The laser
Projects a beam down the tube and shows where it lands. It is fast, it works alone, and it works in complete darkness, which suits a session that has already started.
Its weakness is self-referential: the beam must leave exactly along the axis of the tool’s own barrel. A laser that is out of true will give confident, repeatable, wrong answers.
The Cheshire
A sight tube with a reflective angled face and a crosshair. Nothing in it can drift, and it shows the alignment directly rather than inferring it. It needs daylight or a torch, and it takes a little longer to learn.
The common enemy
Play in the focuser. Whichever tool you use, slop between it and the draw tube tilts it, and the tilt goes straight into the result.
What to buy
If you buy one, a laser you can self-collimate. If you buy two, add a Cheshire and use it to confirm the laser once, then trust the laser for the rest of the year.
The questions that keep arriving
What is barrel play and why does it matter?
Any slop between the tool and the focuser tilts the tool, and a tilted laser aims the telescope wrong by exactly that amount. A compression ring in the focuser is part of the solution.
Can I collimate without any tool?
Roughly, using a defocused star, and it works best as a final check rather than as the whole procedure. It also needs a steady night and a tracking mount to be anything but frustrating.
Last reviewed 17 September 2026