Another SCT Collimation Method - Simple?

[stevous67 (Steve M)]

Hi all,

I know there are many collimation methods out there, some visual based, some software assisted, others supported by simple to complex third party devices. I know, as I have beat up myself trying many of them to find the right solution for me, my equipment and my purpose for astrophotography.

The scope type I'm talking about is one with a fixed primary and an adjustable secondary mirror. I've now tried it numerous times, and now on my Planewave 12.5. I hear that people think this is a forgiven scope to collimate, but to get it right, it has been still challenging. Anyway, if you're interested in having a read on an alternate approach and a variation on the single defocused star, see the link below...

http://www.mpas.asn.au/multipledefoc...ollimation.htm

I always think sharing is good, and I've learnt much more from others than I have on my own. So if this is helpful to anyone, that's great. It is simple, you can do it on your own, and it works.

Bye

Steve

[MarkA (Mark)]

Thanks Steve
Mark

[toc (Tim)]

At the risk of sounding thick - Ive re-read the article a few times, and Im struggling to understand just what you have to do - I get the idea that its difficult to determine if a star is exactly centered, and that trying to collimate with an off center star can lead to problems. After that Im lost

[stevous67 (Steve M)]

Hi Tim,

You're right, collimating on an off centre star is incorrect, that is why I suggested for MaximDL users to turn on their cross hair to determine the central point. Here is where the concentric stars must be in the FOV.

The elongated stars surrounding the centre will help you determine where this collimation point is, thats all.

I'm not sure about other peoples experiences, but in the past I found using a single defocused star could lead to not having this collimation point being central to the FOV. Having extra stars within the FOV helps to determine where this is. That's all.

Cheers

Steve

[multiweb (Marc)]

Very clever Steve. Out of the box thinking. Never considered the field shape with collimation.

[stevous67 (Steve M)]

Originally Posted by multiweb

Very clever Steve. Out of the box thinking. Never considered the field shape with collimation.

Thanks for that Mark.

It's just an idea that is working for me. I just want something that will give 90%-95% accuracy, that is reasonably quick to do, and is most importantly ~ simple to do.

Doing your collimation this way, it's all about moving the defocused stars around your FOV, until you can see the central collimation point is middle to your FOV.

Cheers,

Steve