As an astronomer or as a beginner to the field of astronomy, your first question might be about how the different types of telescopes work. And when it comes to a reflecting telescope, you might want to know the whole thing clearly and then your next step is probably to know about how a reflecting telescope works. Stay with us. You will get it.
“How a reflecting telescope works” isn't anything difficult. Just a few specific things occur inside of it. Today this article will introduce you to those specific things. You will definitely find it interesting and enjoyable. So first learn and then enjoy your observation journey.
What is a reflecting telescope?

A reflecting telescope is an optical instrument designed by two mirrors that are used to focus on the celestial objects. To be more specific, a reflecting telescope is an optical telescope that uses mirrors where lights are reflected at various angles through the optical tube.
Before knowing the working process of a reflecting telescope, we would like to describe the design of it so that you can get a clear idea and understand the process given in the latter section.
Design of a reflecting telescope

There are two mirrors in a reflecting telescope. The primary mirror and the secondary mirror. The primary mirror is angled towards the secondary mirror. These mirrors are curved for a very specific reason.
When the light rays of a celestial object come, they come in a parallel shape. But the curved shape of the mirror gathers the rays into a single point at the secondary mirror. Otherwise, you won't be able to observe an image.
There is also an eyepiece directed to the secondary mirror. This eyepiece magnifies the image of the distant object and makes it visible.
Now let's know how a reflecting telescope works.
n the light rays of a celestial object come, they come in a parallel shape. But the curved shape of the mirror gathers the rays into a single point at the secondary mirror. Otherwise, you won't be able to observe an image.
There is also an eyepiece directed to the secondary mirror. This eyepiece magnifies the image of the distant object and makes it visible.
Now let's know how a reflecting telescope works.
How a Reflecting Telescope Works

A reflecting telescope works by the two curved mirrors (primary and secondary) that are used to focus the object. These mirrors gather light and reflect the targeted image. Let's know the detailed process below.
- In a reflecting telescope, first, the light coming from a distant object will directly go through the optical tube.
- Then the first reflection will occur on the primary mirror located at the bottom of the tube.
- The major part of a reflector is the primary mirror. It will pass the light to the secondary mirror located near the top of the optical tube.
- This mirror will reflect the light for the second time.
- The eyepiece of the telescope directed towards the secondary mirror will catch the light and magnify the image.
- When the magnification occurs, the image will be visible to you and thus you will get a clear view of the object.
After knowing about how a reflecting telescope works, you might want to know how you can focus on it. Nothing to worry about. Let's know in detail.
How do you focus on a reflector?
The focusing method in a reflecting telescope isn't something difficult. You can easily do it yourself. Follow the steps given below:
- First, rotate the focus knob slowly.
- Continue rotating until the object you targeted becomes focused.
- Move just a little bit beyond the sharp focus and switch the direction.
- When you will get a sharp focus, tighten the focus knob until it is locked.
- If you don't lock it, your focus may slip. So don't skip the step.
- When you are ready to refocus on a new object, loosen the focus lock knob again.
- The focus lock knob should also be turned while changing your eyepieces.
- Try frequently and the focusing will be easier for you.
What Does a Reflecting Telescope Do?
A reflecting telescope monitors the area of the electromagnetic spectrum that is visible. Then it finds out all the wavelengths adjacent to it. And finally, it makes the distant objects brighter and visible through the reflection process.
Reflecting Telescope Diagram

This diagram shows you the two curved mirrors, the eyepiece lens, and how they work. The two mirrors work for the reflection of the light. But when it comes to the eyepiece, the magnification occurs depending on the focal length between the eyepiece and the focal point. The shape of the magnified image is formed by this focal length.
To explain more specifically, if your focal length is long, then the image will be smaller and it will be less visual. But if the focal length is short, the eyepiece will magnify a longer image and make the object more visual to your eye.
Along with the eyepiece, the aperture of the telescope plays an important role in this regard. When you observe through a reflecting telescope, the light comes and enters through the aperture. If the aperture is long in size, it gathers more light. The more light you get, the brighter you see the object.
Besides, the larger the aperture, the more crisp and high-quality image will be formed. That means the resolution and the quality of an image depending on the size of the aperture. So the mirrors, eyepiece, and the aperture play a greater role in forming an image.
Advantage and Disadvantage of a Reflecting Telescope
Advantage
- Gives the best view with a larger screen
- Relatively cheaper
- Easy building procedure
- The wavelengths reflect on the mirror in the same way and that's why chromatic aberration doesn't occur.
Disadvantage
- The collimation procedure seems to be a little hard
- Mirror cleaning requirement
- Heavier
Keep in mind
Knowing a telescope isn't similar to using one. As the primary or secondary mirrors are openly settled in a reflector, there is a chance that the mirrors might get dirty after a few days. And if it continues, the mirrors become less reflective within a year. So the mirrors should be manipulated carefully. In this case, don't take any risk. Just clean the mirrors frequently so that you can use a reflecting telescope for a long time.
Along with the cleaning process, a reflector telescope needs to be collimated so that you can adjust yourself with the alignment of your telescope. And this collimation should be done before you get prepared for an observation whether it's an astrophotography session or wildlife viewing.
Conclusion
What we discussed above is simply a description of how a reflecting telescope works, how to focus on it, what it actually does, and what the advantages and disadvantages are. You got the idea of how the reflection occurs and the magnified image is formed.
We have revealed those very basic things that are required for you to know. But still, we might miss something here. If you have any more ideas regarding the topic, don't delay to inform us. If you have something different in the working process, let us know too.
Drop your queries, share your opinions. Happy telescope observation.
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