The image on the left shows the really precise centering of the secondary mirror on the center of the back of the telescope tube. Why is it centered on the back of the telescope tube and not on the center of the primary mirror, you ask? Because it is much easier to center the secondary mirror if you remove the primary mirror first. At least on small Newtonian telescope. For large scopes, it's better to use sheet of paper (green or yellow for better contrast) between primary and secondary mirror.
I have found that for me the biggest challenge with the collimating telescope is dealing with all the reflections from the primary mirror in the secondary mirror and vice versa. It's almost impossible to tell which is which. It becomes much easier if you remove one variable from the equation.
But first things first.
What do you need to try out my method for yourself?
- Newtonian telescope
- I assume you already have that
- Eyepiece camera
- I recommend one with a built-in lens
- manual electronic focus
- Collimation Circles application
- download here: https://github.com/sajmons/CollimationCircles/releases
Next, you need to download, install and run the Collimation Circles application.
In my case telescope is connected to my Raspberry Pi computer with HQ Camera attached. So I will connect to remote camera stream initiated on my Raspberry Pi.
You can run Collimation Circles locally on your Windows or on your Linux machine.
I have used the Tools tab and then Camera video stream tool to connect the remote stream as shown on image on the right.
Then you need to remove your primary mirror. Install your eyepiece camera with built in lenses to see the inside of the focuser tube. You should see something like the picture on the left.
The first thing you need to do is make sure that the secondary mirror is centered under your focusing tube. Once you have achieved this, you should tilt it so that the reflection on the back of the telescope aperture is exactly centered. With the help of the Collimation Circles application, this should be very easy.
Image on the left shows my final result.
I hope you like this method. If you do, be so kind and leave 5 star bellow.
Be sure to read Part 2 of the series of Advanced Newtonian Telescope Collimation available here.
Clear Skies!
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