Need a slight tweak to the collimation

[Nigella Bryant]

Hi all, had a little break in the clouds last night and almost got the C11 XLT collimated. Clouds rolled in before I could finalise the collimation so needs a little tweak next time the weather decides to play ball. 

[jonathan]

The other night mine looked like that scene from 2010 when the monoliths all piled into Jupiter near the end, a black spot right near the edge!  It needs a bit of work...

[kirkster501]

That is not the way to check for accurate collimation.  What you have done is a very "rough" collimation, to get you in the ballpark.  You need to be *at* focus and to observe the airy disk and then check the rings of the airy disk are concentric around the star.  

https://www.cloudynights.com/topic/623603-collimation-of-an-sct-from-scratch-a-photo-guide/

Edited September 11, 2020 by kirkster501

[Nigella Bryant]

7 minutes ago, kirkster501 said:

That is not the way to check for accurate collimation.  What you have done is a very "rough" collimation, to get you in the ballpark.  You need to be *at* focus and to observe the airy disk and then check the rings of the airy disk are concentric around the star.  

https://www.cloudynights.com/topic/623603-collimation-of-an-sct-from-scratch-a-photo-guide/

Thanks for the tip and guide, much appreciated.

[kirkster501]

Just now, Nigella Bryant said:

Thanks for the tip and guide, much appreciated.

You're welcome.  The airy disk can be hard to see and you need a dark sky and a medium brightness star, magnitude 2 or so is perfect.  Too bright a star and I find the centroid of the star drowns out the airy disk and you can't see it properly.

Metaguide has a good collimation tool.  Completely free and excellent.  Lots of videos on how to use it.