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collimation and the secondary.....
[quote=Scooter;297971]Hi Folks,
To be honest I have never been completely satisfaied that I have the secondary right (thus the question) but basically my procedure is:-
Hi Scooter - as Starkler and Rajah note, it is almost there. I've only bothered to respond because of your comment re the secondary; I encountered similar probs when re-coming to grips with collimating.
My solution, when I got to your final photo situation, was to go back to the secondary and re-centre and re-circularize it (for want of a better description) within the focusser tube. Basically, re-adjusting the sec to make sure it was as concentric/centred as possible in within the focusser tube. Then I went back to the primary adjustments - and then did the whole lot again for a third time!
It is my belief that re-iterating these procedures fixed the problem that you have stated you aren't quite happy about in the photo - I did this because no amnount of tweaking the primary from the position your example illustrates would sort that out. Incidentally, I use an Orion sight tube/chesire tool: don't own a laser job but my problem was exactly the same as yours'. My star tests are now producing superb diffraction rings (on good seeing nights!)
I've made similar posts a couple of times in IIS since I sorted my problem out inviting "wiser heads" to comment on my methodology and my assumptions; but so far no-one has responded - though I'm starting to form the opinion, based on other observations, that there are many people out there who really don't know a whole lot about collimation - or at least the finer points. Those that do could well take the attitude that it's much easier to demonstrate rather than articulate in a post: it is very hard to put it in words! (which means probably that no-one could understand my garble, that's why they didn't respond!)
Anyway, I hope it is of some help to you.
Cheers, Darryl.
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