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This article is excellent, and basically mimics my collimation process pretty much exactly, except that I do rely on a barlowed laser to re-check the collimation after repointing the scope at night since its much easier to see and doesn't require me to hold up any extra light.
I use the red triangle on my primary, as Don shows in the article, and to get maximum accuracy I printed a black outline on my barlowed laser paper target that is exactly the same size as the reflected shadow. This makes it even easier to judge the precise alignment - you rotate the barlowed laser until the drawn outline is aligned with the reflected shadow and then adjust the primary until all 3 sides of the reflected shadow are precisely aligned with the 3 drawn lines.
One more thing that Don might have mentioned is the idea of pointing the red triangle on the primary so that each of the 3 points are aligned with the collimation screws. If you do that then it's easy to figure out which collimation screws need to be adjusted.
I also check that all tools agree, as a double-check against doing something stupid - ie the Catseye blackcat and barlow laser must both tell me that Ive got the primary pointed correctly, and the autocollimator and telecat must both tell me that I have the secondary pointed correctly.
One more note - for planetary use where only a couple of mm at the centre of the field are used, precise centering of the secondary under focusser is not required, but you want to be reasonably close. I do check this every time I set up, but normally it doesn't need to be changed.
regards, Bird
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