Collimation: telescope collimation, collimate and collimating a telescope
Collimation is lining up a reflecting telescope's mirrors so that the light they gather arrives at a single point. It sounds like maintenance and it is really a five-minute alignment, but it is the difference between a 130mm mirror performing like one and performing like a 60mm one.
- $305median printed price of the entry instrument
- 5brands with a verified printed price
- 4categories with measured demand
Figures on this page come from the TelescopeCompareHQ price index: 5 brands, median printed entry price $305, every figure quoted from the brand's own page and dated.
- 5 brand product pages verifiedevery figure matched verbatim to the brand's page
- Quoted and dated, never estimatedlast verification pass 2026-09-09
- 4 categories coveredeach with measured search demand behind it
Printed prices, verified
| # | Brand | Entry price | Aperture · Focal length | Source | Checked |
|---|---|---|---|---|---|
| 1 | Celestron | $79.95/unit | Aperture 76 mm apertureFocal length 300 mm focal length | celestron.com | September 2026 |
| 2 | Explore Scientific | $91/unit | Aperture 114 mm aperture | explorescientific.com | September 2026 |
| 3 | Sky-Watcher | $305/unit | skywatcherusa.com | September 2026 | |
| 4 | William Optics | $498/unit | williamoptics.com | September 2026 | |
| 5 | Lunt Solar Systems | $995/unit | Aperture 40 mm aperture | luntsolarsystems.com | September 2026 |
| 6 | Bresser | No price printed on the page; dealer or quote only (checked September 2026) | |||
| 7 | Unistellar | Product page could not be read (checked September 2026) | |||
| 8 | Vaonis | No price printed on the page; dealer or quote only (checked September 2026) | Aperture 50 mm apertureFocal length 250 mm focal length | vaonis.com | September 2026 |
How to think about collimation
- Only reflectors need it. A refractor is sealed and aligned at the factory. Newtonians, dobsonians and catadioptrics have mirrors that can shift, and the ones that get carried shift most.
- Two adjustments, in order. The secondary mirror first, so it is centred under the focuser and shows the whole primary. Then the primary, so the reflection is centred in the secondary.
- A star tells you the truth. Defocus a bright star slightly at high magnification. The rings should be concentric. If they are lopsided, the alignment is off, whatever the tools said indoors.
- How often, honestly. A tabletop dobsonian that lives on a shelf: a few times a year. One that travels in a car boot: check before each session, adjust when it needs it, which will not be every time.
What being out of collimation actually costs you
A misaligned mirror does not make the image dark or crooked, it makes it soft. Stars stop being points and become small comet shapes, the planets lose their fine detail first, and the whole view acquires the quality people describe as the telescope not being very good.
That is why it matters more than its five minutes suggest: a beginner with a perfectly decent instrument that has drifted out of alignment concludes the instrument is poor, and there is nothing in the experience to suggest otherwise.
Which tool, and what each one is honest about
A collimation cap is a lens cap with a hole in it and it costs almost nothing. It is enough to get the secondary and primary roughly right and it is where everybody should start. A cheshire eyepiece adds a crosshair and a lit face and does the same job more precisely and slowly.
A laser collimator is fast and popular and has one catch worth knowing: a laser that is not itself collimated will confidently align your mirrors to the wrong place. Roll it in the focuser and watch whether its dot stays put before trusting it. The star test above is the check that settles any disagreement between tools.
Common questions
- How do I collimate a telescope?
- Centre the secondary mirror under the focuser so the whole primary is visible, then adjust the primary's screws until its reflection is centred. A collimation cap is enough for both steps, and a defocused star confirms it.
- How often does a telescope need collimating?
- A reflector that stays indoors, a few times a year. One that travels in a car, check at the start of a session. A refractor, effectively never.
- Do I need a laser collimator?
- No. A collimation cap costing a few pounds does the job, and a laser is a convenience that introduces its own error if the laser itself is out of alignment. Check the laser before you trust it.
Not sure which instrument you need?
Browse by category
Cite or embed this figure
The median printed price of the entry instrument in each category in the consumer telescope and observing optics market was $305 in September 2026, across 5 verified retailer product pages recorded in TelescopeCompareHQ Telescope Price Index.
Cite as: "TelescopeCompareHQ Telescope Price Index", updated 2026-09-09, https://telescopecomparehq.com/collimation/.