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collimation.....
Hi Shane - after seeing your post I thought somebody ought to at least acknowledge it, even if you've sorted it out in the interim! Not getting any responses is pretty darn frustrating: but I'd have to defend most IIS members and suggest it was just "one of those times."
My own experiences of getting back into collimating after a 30 odd year break were similarly frustrating - and your final comments are spot on, the piccies and advice are just no substitute for learning the hard way! Of course, the luxury of having someone next to you with the patience and ability to show/teach would be super, and learning by yourself still requires you to remember just how you did get/jag it right!!!
From your first post's diagram it looks like the secondary was then aligned and the primary needed adjusting - though when you spoke of repositioning the "primary" I presume you meant "secondary"?
I actually deliberately put my secondary out of position as well as alignment to make myself re-learn the whole process - a sort of sink or "swim you *******" challenge to myself.
I used, to really get on top of the collimating process, an Orion combo sight tube/chesire collimator (about $70, and no, I aint got shares in the company!)
What I found, after re-positioning the secondary by making sure it was centred in the scope tube (ie the spider was centred in the tube) and then making sure the secondary mirror was centred when looking down the focusser tube (centred in the focusser tube's view) AND also turned/rotated so it (the secondary) presented itself as being as near as possible to looking as if it was "round" (as opposed to the fact it is actually oval) THEN you fiddle with the secondary's adjusting screws to get to AS NEAR AS YOU CAN to where your diagram indicates - "bob's knobs" type screws certainly make this bit so much bloody easier!
Then it's down to the primary to move that small circular reflection with its cross towards the centre of the whole shebang - BUT in actual practice I found that after fiddling with the primary I then had to go back and do some more fiddling/adjusting on the secondary (including re-rotating it to get the round appearance, which meant re-adjusting its screws again, cos rotating it requires you to loosen off the screws that you've just tweaked!) and then back to the primary again - 3 or 4 back and forths till bingo, it was all aligned. Subsequent star tests to reveal diffraction rings revealed it to be spot on: since then its been only a tiny tweaking of the secondary to maintain (unless something untoward hapens....!)
Hope this helps, and "bob's knobs" or your own (cheaper) version of these is so bloody helpfull with all the above (no shares there either!)
Cheers, Darryl.
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