Telescope Collimation

  • Maruša 

Introduction

Imagine taking your partner on a date to your favourite stargazing site and pointing it at the sky, only to find out the star you named after them for an anniversary present is only a blurry dot in the sky. You try and try to focus it, but it still does not work. Does this mean that you need to buy a new telescope or that you simply need to collimate it? If the star you wished to observe is only extremely unfocused, then no need to worry – you did not buy a broken telescope.

Telescope Collimation

Source: Wikipedia

Collimation in General

Collimation is a lot like owning a house. You own it, live in it, but you still need to check everything once in a while if you want to keep having a roof over your head. Be that as it may, you still find some special snowflakes that spend their Saturday evenings checking if everything works as it should. And if you are an astronomy buff, collimation can be the same. But it does not have to be. Usually, the alignment of a telescope can be done in a couple of minutes.

To put it simply, collimation can be defined as the physical alignment of the optics of a telescope. If a telescope is not collimated correctly, you will not be able to focus it, no matter how hard you try. Collimation is a means of aligning the mirrors of a telescope in order for it to perform as best as it can.

Does my Telescope need Collimation?

Even though anyone can tell something is not right with a telescope if all they see is a blurry image, there is a test your telescope can take to tell if it needs to be collimated or not. For this, you will need a dark sky, a bright star, and a telescope. Stars are a great way to do so, as the test is also called the “star test”.

Begin with pointing the telescope at the sky and focus it on a bright star. Try positioning the star in the centre of the field of view and focusing it as much as possible. Then, begin defocusing the target. Pay attention to the diffraction pattern of circles that surround the star. If the circles are not concentric, this means that your telescope failed the test, and you need to align it.

Telescope Collimation

If your telescope failed the test then Huston, we have a problem: your telescope needs to be collimated. Collimation is a three-step approach. But depending on whether you have someone to help you or not, you should be able to do this in a couple of minutes. The first step is to roughly align the primary mirror.

Telescope Collimation

Source: https://www.qsstudy.com/physics/reflecting-telescope [accessed 28 Nov. 19 ]

The second step would normally be to align the secondary mirror in order to ensure that the secondary mirror is feeding all of the primary mirror’s light to the eyepiece. The third step is to go back to the first. Did it worsen, or did it improve? Move the screws as needed or leave them be. If you are a collimation first timer, do not worry, as it will get easier every time.

Conclusion

If you find yourself in a pickle, having issues finding the perfect focus, collimation might be the culprit. Telescope collimation does not need to be so burdensome that it puts a black cloud over your enthusiasm for observing the sky. We hope this article will help you so that next time you take your partner star gazing, your telescope will not be the one to ruin it.

Summary
Telescope Collimation
Article Name
Telescope Collimation
Description
If you find yourself in a pickle, having issues finding the perfect focus, collimation might be the culprit. Telescope collimation does not need to be so burdensome that it puts a black cloud over your enthusiasm for observing the sky.
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Optics Trade Blog
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