Reflecting telescopes – also known as Newtonians or simply as reflectors – are a popular choice of instrument for both amateur and professional astronomy. The invention of the reflector is credited to Isaac Newton in the 17th century, who created them as an alternative to the common refractors of the time. At the time, refractors had an unsolvable chromatic aberration problem, meaning that the images were somewhat distorted due to their lenses inefficiency in focusing colors to a specific point.
While both designs have their pros and cons, and neither truly outweighs the other, reflectors are sometimes preferred because they do not have the issue of chromatic aberration, are more affordable, and come in much larger sizes. However, they do require more maintenance. Due to their design which has a primary and secondary mirror, the optics have to be aligned to prevent distortion. The best way to do this is to use a laser collimator. These simple devices will save you a lot of hassle with your reflector. Read on to learn more about what they are, how they work, and which collimators are best for you.
Does My Telescope Need Collimation?
There is some debate as to how often telescopes need collimating. Some astronomers and backyard stargazers recommend collimating your telescope before each use. Others deem this unnecessary, and suggest only collimating your telescope as need be.
You should always collimate your reflector after it is transported. Motion, especially in cars or planes, can disturb your telescope’s mirrors, so it is likely that if you have taken it along on a journey that the optics will be misaligned.
Next, you need to familiarize yourself with bad viewing conditions, as opposed to a faulty telescope. Twinkling stars (scientifically called scintillating), other atmospheric interferences, light pollution and more can confuse the untrained eye into thinking there is a problem with the telescope when it is actually fine.
Telescopes only have to be collimated if viewing the sky through them is inexplicably unstable or distorted, and minor adjustments (like focusing the lens) make no difference.
You can use the star test to determine if your telescope needs to be collimated by setting it up and using it as you would ordinarily. Note that temperature and conditions can affect the accuracy of this test. Allow your telescope to adjust to the air temperature by letting it rest for an hour so before you do the test. If there is excessive scintillation, the star test is unlikely to succeed.
Aim your telescope at a star, preferably a bright one that is high in the sky. If the out-of-focus rings of the star are perfectly concentric, there is no problem. If you notice that the rings of starlight are offset to one side, you will have to collimate your telescope.
Best Laser Collimator Reviews
Be careful, as many lasers are cheap or uncollimated, so investing in them will waste both money and time in the long run. Here are five picks you can choose from to ensure quality, efficiency and accuracy.
SVBONY Red Laser Collimator
This collimator is designed with Newtonian telescopes in mind. It allows easy collimation for 1.25” and 2” reflectors, and includes a removable 2” adaptor. Its red laser has seven brightness levels that you can adjust according to light or viewing conditions. What is great is that this feature can be used to collimate your telescope in the daylight if need be. It is strong, but lightweight and has a solid metal case. The laser’s battery and an instruction manual are included with your purchase.
Pros:
- The brightness of laser can be adjusted and is suitable for daytime use.
- The laser includes its own adjustment screws.
- It is precise and easy to work with.
- It is an affordable option and is a great choice for amateur stargazers.
Cons:
- These lasers are not collimated out of the box and may require initial tweaking before you can use it with your telescope.
- It does not fit snugly into some draw tubes. There is a chance you will have to tape or tie it down to keep it still.
Astromania 1.25” Laser Collimator
Sharing many features with the SVBONY above, this red laser collimator is perfect for Newtonians, and features seven brightness levels. The laser is pre-adjusted for telescopes and is built to fit 1.25” reflectors. Its output power is less than 5mw, and so is easier on your eyes. It comes in an aluminum case and includes an easy to understand step-by-step manual. The battery is removable.
Pros:
- Seven brightness levels.
- The laser is pre-collimated, though can be adjusted if you like.
- It is safer and less likely to hurt or damage your eyes.
- Battery is removable and replaceable.
Cons:
- Battery is not included with purchase.
- It is too dim for bright conditions or daytime use.
- This laser is not intended for Barlow lenses and will be inaccurate if used with one.
Orion 5691 LaserMate Deluxe II Telescope Laser Collimator
This laser collimator features a rear viewport for easy collimation if you are alone. Cased in an aluminum house, the 3mm flange ensures stability, decreasing the chances of shaking and inaccuracy. It is built to fit all 1.25” reflectors and includes the battery it requires to run. You also get a free extra marker in case your telescope does not have one designated and you have to install it yourself while collimating.
Pros:
- Fits tightly into draw tubes and is unlikely to come loose.
- Rear view is excellent for solo stargazers, and saves you time and effort.
- Battery is included.
- Made-to-fit extra marker for those whose telescopes do not have one pinpointed.
- Full instruction manual included.
Cons:
- This laser is not pre-collimated.
- It is not a cost-effective choice.
- Lacks the sophistication and extra features of competing brands.
Meade Instruments 608001 Laser Collimator
You can use this laser collimator with your Newtonian or even certain Newtonian hybrids. It fits 1.25” focusers, but comes with a 2” adaptor. You can adjust the brightness of the laser, and the collimator is powered by a single battery, included in your purchase. It may not have some of the bells and whistles of other brands, but it is a strong, durable and precise product, complete with a one-year warranty.
Pros:
- Compatible with both Newtonian and hybrid reflectors.
- The laser’s brightness is adjustable.
- Battery is included with the purchase.
- Includes a 2” adaptor.
- It’s durable and Meade offers a full year warranty.
Cons:
- The laser’s battery runs dry quite quickly. Spares may be necessary.
Gosky 1.25” Metal Laser
Made for 1.25” Newtonians, this is another affordable option for beginner astronomers. You can choose between seven levels of brightness, and the collimator is a red LED laser. It is cased in a black metal house, coated in aluminum. Its output power ranges from 1-5 mw, and helps in preventing eye strain. An instruction manual is included with the collimator, and you will get a 30-day, no questions asked warranty upon purchase.
Pros:
- Seven levels of adjustable brightness.
- It is an affordable choice.
- Low output power for safer use.
- A full warranty is guaranteed for a month after purchase.
Cons:
- Battery not included.
- Build may be a bit too narrow to fit snugly in some draw tubes.
What is the Meaning of Collimation?
The definition of ‘collimate’ is to make something parallel by bringing it into line. In astronomy, the term means to adjust the optics of a telescope according to your line of sight. Collimation is therefore the process of setting the mirrors in your reflector, to produce a more accurate and stable image through your eyepiece.
What is a Laser Collimator?
A laser collimator is the device you use for aligning your reflector’s optics. Not all lasers are collimated, though it looks like they are because the beams of light are so concentrated and narrow. A laser collimator uses a beam that is already collimated, so as to have a precise guide when adjusting your telescope.
What Does a Laser Collimator Do?
Beams of light diffract when they pass through refractive objects. This means that the light is unparalleled, and scatters before it reaches the eyes of the observer. In a telescope, where the image produced by light is important, this causes varying degrees of distortion. Collimation prevents this scattering and diffraction by aligning rays to be exactly parallel with each other, creating an accurate and ordered beam of light.
Laser collimators work by bouncing off of the mirrors in a reflector, and pinpointing the exact angle that the light hits. Most reflector telescopes come with markings on their primary mirror. When you shine a laser collimator through the tube of your telescope, its light reflects off of your secondary mirror and onto your primary one. In a correctly collimated telescope, the laser will hit the primary mirror right on its mark. If not, you will know to adjust the secondary mirror accordingly, until the laser points to the designated spot it is meant to hit.
How to Use a Laser Collimator
Though most laser collimators are written with a lot of jargon that only professionals can make sense of, using them is fairly straightforward and simple. It is useful to have a helping hand while you do this. While one person can certainly get the job done, having another to do the checking or adjusting will save you a lot of time going back and forth between the two.
Laser collimators have to be perfectly still while they work. Insert yours into your drawtube – the spot that your eyepiece usually sits in. The slightest shaking, wobbling or instability can throw the entire collimation process off, so lock it in place to avoid unnecessary movement while you work.
Start by checking the secondary mirror. When you turn your laser on, its light should shine in the center of the primary mirror’s marker. This marker is typically a black (or dark) ring. If it is not centered, you will have to adjust the secondary mirror by hand. Have a look at its screws. You might need specialized tools (like an Allen key) to adjust it. If you have to tinker here, you simply play it by ear and keep adjusting it until it is set.
To collimate your primary mirror, all you have to do is align it so that the laser falls dead center on its target. Rarely do telescopes need drastic adjustments here, so be gentle and work slowly to avoid causing more misalignment than what you began with.
When replacing and tightening your screws again, take care. This may cause the laser to pop out of place.
How to Collimate a Laser Collimator
Sometimes – much to the frustration of stargazers – laser collimators need collimating! A misaligned laser will, of course, throw your telescope off center if you are using it to line your mirrors up; or it will make collimating much more tedious than it is intended to be. The easiest and quickest way to spot an uncollimated laser beam is if it shines at an angle. Remember that collimation needs a beam that runs parallel to your focuser’s axis. Beams that are clearly not parallel means that your laser will need collimating itself before you can collimate your telescope.
Collimating a laser is just as easy as collimating a telescope. You will have to find a way to rotate your laser while keeping it straight and aimed at a single point (on your wall is fine, as long as you can see the dot). When you rotate your laser, the shape of the light will tell you all you need to know. If it stays a dot, your laser is collimated. If it becomes a circle, you will have to adjust it. Most of the time this only calls for a few adjustments to the laser’s screws. It will take some trial and error, but with patience you will be able to align it yourself.
This will only work if you keep the laser straight. Shaking, bumps or changes in direction will interfere with the test.
Are Laser Collimators Worth It?
Laser collimators may not be the most crucial component of your telescope setup, but they spare you a lot of hassle when it comes to maintaining your Newtonian. If your mirrors are misaligned and you do not have a laser collimator, correcting them is hard and tedious work. When you consider that laser collimators are often affordable (or at the very least, reasonably priced), it makes sense to invest in one to improve your overall stargazing experience.
If you travel often with your telescope the need for a collimator becomes more pressing. Reflector mirrors are sensitive to motion and could easily come loose. Laser collimators will save you a significant amount of time and effort.
The verdict is that laser collimators are a convenient tool to have and are well worth the money you will spend on them. So long as you know how and when to use it – and you certainly do now – you cannot go wrong in buying one.