Why Are Telescope Images Inverted?

Why Are Telescope Images Inverted

Imagine you have bought the very first telescope in your life. During the night, when you are about to view the sky super excitedly, you discover that the view and images of your telescope are upside down! Before you experience an imaginary heart attack thinking your brand new telescope is defective, let me tell you that your telescope is absolutely fine.

Telescope images get inverted if the optical elements are in pairs. This can happen for both lenses and mirrors.

The image inversion is a complex yet necessary process for the telescope. To understand it fully, you need to go through this whole article. I’ll try to explain everything as simple as possible. I’ll also discuss some ways to deal with the inverted images, especially if you are using the telescope for terrestrial view.

Why Telescope Images Get Inverted?

First of all, it is not like you have been tricked with a telescope whose images come out inverted. The thing is that some telescopes are designed to be like this. The images are inverted because of the way the telescope brings the light to focus.

Usually, if the telescope has its optical elements in pairs, its images will be inverted. This has something to do with both lenses and mirrors. For example, a Newtonian Reflector Telescope has 2 mirrors. So if you have a Newtonian, you will see things upside down while viewing. Even the images of the refractor telescopes are also inverted.

But if you use a Nasmyth-Coudé, you will see that the objects are reversed from left to right. This is because this telescope has 3 mirrors.

This is how it actually works. The lenses and the mirrors help magnify the images so you can understand them in a better way.

You may not have seen this coming but here it goes – the lenses of your eyes work exactly the same way as the lenses of your telescope. Your own lenses process and invert every single thing you see and then your brain works on them and orientates them in a way so you can see and understand your environment in the best way possible.

And just like that, your telescope’s lenses and mirrors orientate the images in an inverted version to give you better visibility only so you can view the sky much clearly.

As you see, it enhances your capability of using your telescope more efficiently. This is why astronomers work with their telescopes and learn to get used to the inverted images because in that way they can get the most out of their telescopes.

However, if you are a beginner or an amateur, the inverted images of your telescopes should be no less than a problem. So, to help you out with the inverted images of your telescope, I am going to suggest something useful. If you can follow that while using your telescope for terrestrial land view, your problem will be solved right away.

So, check it out and help yourself!

Using A Diagonal For Reflector Telescope And Cassegrain Telescope

If you have either a Refractor Telescope or a Cassegrain Telescope, you will have to use a “Star Diagonal” to correct the inverted images of your telescope. The diagonal will correct the image by keeping the right side up. But from left to right, the images will still be backward.

However, if you are not comfortable with that and want the images to be completely corrected, you should use a diagonal called Erect-Image Prism diagonal. It will help you see the images exactly the way you see real things. 

Using A Diagonal For Newtonian Reflector Telescopes

On the contrary, things will be a bit complex if you have a Newtonian Reflector. Its images are inverted and it is not that effective for terrestrial land use. There is not much that you can do to correct the view.

First, while you are using a star chart with your telescope, keep that chart upside-down. Then the orientation will change when the starfield shows up in the telescope’s eyepiece.

Where To Find A Standard Diagonal

If you are looking for a standard diagonal for correcting your telescope’s inverted images, you should check this one out now.

Using A Diagonal All The Time

Although you can solve your problem by using a diagonal, you should not use it every time you use your telescope to view the sky. Because while you are using a diagonal for one problem, it is creating two new problems.

First of all, the diagonal lessens the amount of light that your telescope can collect from the sky. As a result, you cannot expect to have a quality experience that you could have if you used the telescope without the diagonal.

Secondly, when you add an external element to your telescope, it can cause additional distortions and aberrations to your view. That again affects the telescope view negatively.

Inverting Images For Astrophotography

You can easily invert your images for astrophotography by using different photo editing software. There are tons of free photo editing apps on the internet. Any of them will do the work.

Finderscope As An Alternative

If you want to use a finderscope instead of your telescope, here is what you need to know:

Achromatic

Finderscopes, smaller than telescopes, have lenses to magnify the telescope’s view. As they also use lenses, their images are inverted. This can create problems at first while finding the objects. But you can solve that by keeping your star chart inverted.

Reflex Sight

This kind of finderscope does not have any lens. It uses a straight-through observation of the sky without any magnification. So it does not invert the images. It has circles in its reticle to show you the part of the view which matches the eyepiece’s field of view.

If you want to buy a Reflex Sight finderscope, here is the bestselling one named the Telrad Finder.

Final Words

After all the discussion, now I hope it is pretty clear to you that your telescope is completely okay. Just follow the solutions and you will be able to use your telescope to its fullest. Best regards for your telescope images!

Muntaseer

I have wondered how the Stars and Moons look like for many years. I’ve fallen in love with Cosmology since I was a boy. I am writing these articles to share my love for astronomy with you.

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