Is this a collimation problem, focusing, or just not well guided?

[yusbot]

Hi folks,

I have GSO RC8 and have been trying hard to get it collimated perfectly.
But it seems that the stars are still not well rounded, they shaped like a diamond ring.

Does it mean that my collimation is still not right enough? Or it just a matter of focusing problem? or not well guided?

I took this picture of M83 at 300s with QHY9.
Thanks for your feedback guys!

Regards

[byronpaul]

Hi,

This looks like a collimation problem to me.

If you were to defocus on a bright star, I think you will see the secondary shadow isn't centred. If so, re collimate with that in mind.

What is your collimation procedure?

Paul

[Somnium]

+1 to collimation, if it were guiding or focus issues then the stars would be a consistent size. these stars look like mini comets which is a sure sign of collimation

[yusbot]

Oh man, it is pretty hard to collimate this scope, i'm gonna kill myself.
I follow procedure from Michael Kirk on YouTube (https://www.youtube.com/watch?v=2EC5N5bfB9A)

I think I have to move the primary mirror a little bit, that in turn it will also lead to move the secondary, and the focuser as well, am I right! :doh:

[Malcolm]

Try this link: http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide .htm

[doppler]

Here's a user manual for the astro tech rc, it has a good read about collimation
https://www.astronomics.com/documents/astro%20tech/astro-tech%20at8rc%20manual.pdf