How to Collimate a Telescope: An Ultimate Guide

How are you doing with your brand-new telescope? You might have just assembled it and now trying to figure out the other specifications. Of course, you are eager to get those amazing views and make the best use of your telescope by now. But do you know how to collimate a telescope?

It sure sounds like a tough call. Well, how about I tell you that it is not as difficult as it sounds. Besides, you have already come that far without any issues. So, why wait now?

Therefore, allow me to guide you all the way to collimate a telescope within a short amount of time and make sure that you are enjoying a great experience.

 Why Collimate a Telescope 

In general, collimating a telescope means adjusting the lenses so that it maintains a parallel alignment in the optical field.

The process helps to focus better and to produce a clear and sharp image. You can think of it as tuning your guitar. 

You tune your guitar whenever you think it needs a bit of correction with the nodes, right? Just like that, you should also keep on collimating the telescope as many times as you need to get that precise image.

However, if you skip this process, there wouldn’t be much validity left of using the telescope because the results will be blurry and misleading.

Therefore, it is very important to learn how to collimate a telescope to get accurate results. 


How to Collimate a Telescope

As I have already pointed out the importance of collimating a telescope, you might be thinking about the difficulties that come with the process. 

Well, don’t worry about that. In this article, I am going to introduce you to some simple steps of collimating a telescope. So, without wasting any more time, let’s jump into it.

  • Centering Secondary Mirror

To start the process, the first thing you need to do is to center the mirror that you will see by looking through your focus tube.

This mirror is called the secondary mirror of your telescope. You’ll get three additional screws with the focus tube. And the main idea is to use these screws to place the secondary mirror right into the center.

At this stage, you’ll also notice some mermaid reflections. However, you should not pay any kind of attention to them and focus on the alignment only.

  • Adjusting With the Cheshire Eyepiece

After you are done with centering the secondary mirror, it is now time for you to make sure that the primary mirror is placed in the center of the Cheshire eyepiece.

The Cheshire eyepiece will guide you to align the optical planes and axes of your lenses and mirrors.

Again, it is very much possible that you will notice some reflections both in the secondary and primary mirrors at this stage.

These reflections turn out to be quite disturbing while using the Cheshire eyepiece. However, we are going to sort that out in the upcoming steps. 

  • Aligning Primary Mirror

To complete the alignment of the primary mirror, you’ll need to use the screws that are located on the rear side of the cell.

Of course, a Cheshire eyepiece will work great here. Make sure that the reflections are properly aligned.

If you are dealing with a laser collimator, the results might seem quite impressive. 

All you need to do for that is to adjust it in a way that your collimator’s Target is always on the return spot.

And for better results, I strongly advise you to carry out this step once in a while. It will be very helpful for your telescope.

  • Precise Defocusing 

Now that you are done with the mirror alignments, it is time for you to start working on focusing and defocusing.

For starters, take a 200x eyepiece. Now, point your eyepiece at a bright start. It’s better to keep the brightness moderate.

After that, slowly begin to defocus. Make sure that you are working on it directly and not doing it diagonally.

When you start your defocusing, you’ll observe some interesting things. As you are working with a bright star, you will start witnessing its diffraction rigs of it. 

It will appear like there is a central hole and it is getting surrounded by the diffraction rings of the star.

However, if you notice that the rings are quite bunched in a single direction, you should move the screws and take that bunched area as close as possible to the field view.

  • Re-Centering the Object

At this stage, it is time for you to re-enter the object. For this, use the adjustment screws and carefully adjust the position by taking a small number of turns.

After that, observe the changes in the star patterns again. This time, you will see a set of rings that are concentric.

Of course, you need to make sure that the star is properly placed at the center of the view field. Otherwise, you can end up having the same bunched result again.

However, if you do end up with that, you can always return to the first step and carry out the entire procedure once again.

  • Increase Magnification 

Now, you have almost reached the end of collimating your telescope. After making sure that you have successfully defocused the star and got the concentric view, start working on the magnification.

I recommend you increase your level of magnification up to 600 times. However, it greatly depends on the magnification strength of your telescope.

Therefore, you won’t need that many adjustments if the magnification of your telescope is higher. And thus your collimation is done.



So, now that you have learned how to collimate a telescope, when will you try it on your own?

If you are still confused about the procedure, don’t worry. You know it takes a bit while to get the hang of it.

However, I advise you to read all the steps first and then go through each of them separately. Be patient and follow the instructions carefully. 

Hopefully, within just a few hours of practice, you’ll be able to pull these all out like a boss.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top