Laser collimators are used for aligning the optics of Newtonian reflector telescopes and some catadioptric and Cassegrain telescopes if need be. Laser collimators project a beam of light down your telescope tube and allow you to make sure your optics are aligned by getting light to hit the center of your primary mirror and bounce back perfectly into the focuser.
Laser collimators are an extremely useful tool for your telescope, and there are different models to choose from based on your budget and requirements. Lasers are best used not on their own but in conjunction with other collimation tools and methods, such as a collimation cap/Cheshire which should always be used to check for coarse secondary mirror alignment before using the laser. Checking your collimation on a defocused star after you use the laser collimator is also always a good idea.
Advantages & Disadvantages of Laser Collimators
Laser collimators are superior to regular Cheshire collimators and collimation caps in that they are much more sensitive to misalignment, making them arguably a must-have if you have a telescope with a focal ratio below f/4.5 or so. They are also easier to use in the dark if you have set up your telescope after dark. Laser collimators, theoretically, should be able to offer near-perfect alignment accuracy just as good as collimating on a defocused star at high magnification.
Laser collimators can be used to collimate Schmidt-Cassegrain, Ritchey-Chretien, and other Cassegrain-type telescopes if you know what you are doing, though these telescopes are best adjusted by collimating on a star, and using a laser with them may not be the most intuitive or affordable option.
Laser collimators are not perfect, however. They are extremely sensitive to mechanical misalignments in your telescope that may not ultimately matter, such as the screws or compression ring in your focuser de-centering or tilting the laser. They can also make you think your secondary mirror is aligned when it’s actually rotated out of alignment and tilted severely, which may be hard to know if you don’t check with a collimation cap or Cheshire first. Lasers can also be rendered nearly useless if the laser itself is not aligned with the barrel of the collimator, which requires adjustment with the laser sitting in some sort of V-block to correct.
Laser collimators also require that you put an accurate center dot on your primary mirror. Without one, they are nearly useless for collimation.
You probably should get a laser collimator if you:
- Use a reflecting telescope with a focal ratio of f/5 or faster
- Observe a lot at high magnification
- Have a sturdy, metal focuser
- Do astrophotography
You probably won’t want a laser collimator if you:
- Have a focuser with any play or wobble, such as a plastic rack-and-pinion focuser
- Use a slow f/ratio reflecting telescope
- Use a telescope which doesn’t require frequent collimation
Best Laser Collimators: Our Recommendations
1. Best Performance Laser Collimator – Howie Glatter
The Howie Glatter laser collimator offers superb machining accuracy and a laser that is certain to be dead-on from the factory. Numerous alternative lenses, upgrades, and accessories are also available for this collimator. The hybrid 2″/1.25″ version can be used with either size focuser without any difficulties or concerns about decentering with an adapter. However, without a TuBlug, which costs as much as the laser collimator, you do have to look into your focuser to check your primary mirror alignment and then go back down to your adjustment screws instead of being able to check your alignment in real time, which can be a bit of a pain.
2. Farpoint Laser Collimator
The Farpoint laser collimator is similar to the Glatter in basic design and advantages. It’s a great collimator and comes in a 1.25”/2” hybrid barrel for use in any size focuser without the need for an adapter. However, compared to the Glatter, it is a little harder to see very small amounts of misalignment, and the family of accessories and other products is not as diverse as what is offered for the Glatter.
The Glatter TuBlug is an extremely useful accessory for the Glatter and Farpoint collimators if you want to be able to collimate without having to go to the back of the telescope for adjustments and then check alignment looking down from the front of the tube. It also amplifies the sensitivity of your laser to miscollimation. However, it’s quite expensive and may induce mechanical misalignment/sagging if your focuser cannot handle it.
3. Hotech SCA Laser Collimator
The Hotech SCA laser collimator fits in either a 1.25” or 2” focuser using its proprietary “self-centering” rubber adapters. It also has a built-in 45-degree window, so you can use it even while adjusting screws at the other end of your telescope. However, the SCA rubber adapters can have issues with some telescopes, especially very fast instruments.
4. Best Budget Laser Collimator: Apertura Laser Collimator
The Apertura laser collimator uses a 45-degree window like the Hotech SCA laser, though you’ll need to provide your own 1.25” to 2” adapter. This is the same laser that is thrown in with the Apertura AD Dobsonians. It’s a lot less accurate than more expensive lasers due to the lack of a precision 2” adapter, grid lines, and machining tolerances. There’s also a pretty good chance the laser will arrive misaligned with the barrel from the factory, making it useless until you adjust it in a V-block with the (thankfully exposed) hex key screws.
5. Cheapest Recommended Laser Collimator: SVBony Laser Collimator
The SVBONY laser collimator is similar to the Apertura laser in design and lack of precision, though it’s cheaper and does include a tight-fitting 1.25” to 2” adapter by default. Like the Apertura laser, many of these lasers ship misaligned with the barrel, requiring you to adjust the alignment in a V-block. However, the SVBONY laser’s screws are hidden behind rubbery coverings, which you’ll need to poke through and destroy to access the adjustment screws with a hex key.