Old 01-12-2018, 08:30 AM
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Marke (Mark)
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Originally Posted by Peter Ward View Post
Well, I have to say I was amazed to see a FWHM of 1.36"....but have no doubts about the mechanical rigidity. I've never experienced meridian flip issues etc....the task now is to get some quality data

Hummm M42 is up!

Indeed. Tiny changes. As for the GSO....Really? I've not experienced that problem.
Yep every time you loosen or tighten the push pull screws there is a little bit of shift , I've had it on both my RCs
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Old 01-12-2018, 08:50 AM
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Atmos (Colin)
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That FWHM map is a thing of beauty Peter!
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Old 01-12-2018, 11:11 AM
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multiweb (Marc)
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Originally Posted by Peter Ward View Post
Hummm M42 is up!
That could be interesting, see how many stars you can get in the trap with multiple sort exposures.
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Old 01-12-2018, 11:18 PM
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Originally Posted by multiweb View Post
That could be interesting, see how many stars you can get in the trap with multiple sort exposures.
Perhaps I should take bets?

But have to say Im very chuffed to see things work as advertised.
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Old 17-12-2018, 06:39 PM
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Originally Posted by Peter Ward View Post
Not pain Paul, more puzzlement. I am very happy with the data out to the edge of the 16803...with FWHMs under 1.9 arc sec.

I think Atmos is correct...CCDinspector is not perfect. I can literally change the focus 10 steps (about 1/1000th) in the same location and it gives me a different result.....as to why? A mystery so far.
I found CCD Inspector to give slightly variable results. Mostly the same but yeah sometimes it would shift and you hadn't done anything. I think its good for an overall close collimation but eyepiece on a night of good seeing is the go for that final tweak.

Perhaps CCD Inspector is simply being influenced by seeing when you are getting that close. I know my CDK on a night of poor seeing is unable to be focused. That must affect CCDinspector calculations. I presume its using FWHM calculations to tell.

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Old 25-12-2018, 07:01 PM
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It's great that you arrived at a terrific result. I read through the link to your website and test results and was surprised that your final use of CCDI was based on a ten min exposure. Seems to me that there would be too many variables in such an exposure...tracking, atmosphere, etc. When I use CCDI I take ten x 10 sec exposures and let CCDI average them. I find these results to be quite repeatable. Anyway, probably you do this and I missed it somewhere.

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Old 27-12-2018, 09:23 AM
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Hi Peter,

Thanks for sharing this! As you you see from a separate thread having progressed on from a Newtonian, I am going through a learning curve with collimating CDK type scopes myself.

At the moment, using a Newtonian laser, my secondary appears centered, but the field is not, and I am getting very slight elongated stars as per your website blog.

In addition to what you have described, just a question - would simply using the secondary to find the centre of the field first and then the primary to remove any elongations also work as a technique as well?
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