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Walking on the Moon

SCT Collimation software


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Hi guys.

I'd like to know if there is any software that can help me with collimating an SCT.  What I'd like to do is plug either my DSLR (which is my main imaging camera) or my Superstar (guide camera) into the scope.  Use that to get the difraction rings on screen.  I'd like to then have some soft of aid that I can compare with that will help to to get perfect collimation... or better still something that analyses the image and tells me how far from perfect I am (a bit like the focus number from BackyardEOS.

I'm using Windows 10, that's about the only limitation that I have.


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There is a neat little software, might that help, it's free and tiny simple effective.


It overlays concentric circles on the image whether static image or live feed from camera. I used it on static image for reflector just on mirrors.

Edited by happy-kat
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Let us know how you get on with that software if you try it.

I have tried loads of different things involving video cameras, overlays, cut outs.......the result always looked ok on screen but when used against the sky the collimation wasn't that great.

In the end I decided to bite the bullet and get the Hotech CT collimator. By increasing the distance of the lasers from the SCT you can make it even more accurate, and when I finally settled on the collimation and star tested it the result was as good as can be.

The only thing is, it is an expensive bit of kit, and once you are happy, it is likely to spend a long time in it's case not doing anything. SCT's tend to hold collimation pretty well, and I haven't had to use my CT Collimator again since the initial use., which makes it a pricey ornament....

Can you not collimate by eye on Polaris? You do need a fairly decent high power eyepiece for best result, something like a 5mm.


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I've always used a high-power eyepiece and a medium-bright star to check/adjust collimation visually, I've never found any other aid useful for getting a more accurate result. The best results are obtained using the diffraction rings on an in-focus star (rather than a de-focussed donut) but seeing conditions have to be good for that - on the other hand, if conditions were not good enough to see diffraction rings then perfect collimation wouldn't be helping much anyway :)


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I'm going to give Al's a try.

The whole idea is that I want to try to remove the Mk.1.Human.Eyeball from the equation as much as possible.  Thanks for the heads up.

What I'm thinking is to use it next time I collimate.   Will use it on a defocussed star, then afterwards will focus and use the defraction rings to either check, or get that final tweak.   Either way, it will make life easier. :)

Edited by cjdawson
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