Hi guys,
Just really struggling with collimation of my Newtonian at the moment. I think that I have nailed it through the cheshire, but I go out and its off! Its not off by a huge amount but stars on the edge of the frame are always slightly different to one another. Also I can never seem to get the diffraction spikes perfect! A real eye sore!
Anyway, this is all done with a Chesire/Sight Tube combination from Astrosystems. I think the problem is when they say stuff like, 'make the secondary a perfect circle underneath the focuser', but for imaging, the max error allowed is so small that im sure that I wont be doing it good enough. Same goes for both primary and secondary tilt collimation. The only part of collimation that im at least kinda certain on was centering the spider vanes, because I could use calipers! And that gives a definitive amount to move something by! Not just, awww yea mate, that looks centered to me when I hold my head this way!
'Make sure the clips of the primary are all equal in the secondary', but there is again just so much room for error there without you even knowing it.
I have an Autocollimator coming any day now, which might help, but I feel like I am missing something. Ideally a real time graph of some sort made by the camera would be best, no error introduced by changing from Cheshire to camera etc. Something like the FWHMeccentricty script that PixInsight produces.
I cant find any information online regarding proper, high quality newtonian collimation. And I know that it exists cos I see it in images everywhere! So either someone is holding onto their secret sauce or I just suck at collimation!
Am I crazy or just bad at collimation!?
Dan
EDIT: Here is what I am talking about. https://i.imgur.com/js7EWdZ.png, you can see that the right hand side of the image is causing the troubles, and that might be linked to the spider vanes splitting on the right side as well.