Thread: 1st Collimator?
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Old 23-05-2020, 09:18 AM
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Outcast (Carlton)
Always gonna be a NOOB...

Outcast is offline
Join Date: Oct 2008
Location: Cairns, Qld
Posts: 1,130
Hi Filip & welcome to the forum,

Collimation is not quite as scary as it sounds but, it pays to have an understanding of the process.

My experience (which is not very substantial) as a relatively newcomer to collimating newtonians (my 12" Truss Dob) is that a combination of a collimating cap, cheshire eyepiece & a good laser make the job relatively straight forward once you understand what you are trying to accomplish.

I know people who can collimate wonderfully using just a cheshire eyepiece or collimating cap but, I am not one of them. Conversely, despite claims from some manufacturers, collimating with just a laser can actually result in poor collimation.

Best guide I have found for collimating a Newtonian reflector is the Astrobaby guide; very well explained process with pictures to guide you in what each stage should look like. It is vital that you follow the process & get each stage correct as it influences the outcome of the next stage. My first go took me close to half an hour but, after only a few goes, I'm down to probably 5 minutes tops...

I use a homemade collimating cap & a $13 Ebay Cheshire eyepiece (short one) for checking secondary alignment & a Hotech laser for confirming secondary alignment & adjusting my primary mirror. I chose the Hotech because it is self centreing & is not affected by the uneven pressure exerted by grub screws or even the brass compression rings. The Hotech is not a particularly cheap item & maybe a cheaper one would do the job but, I like using it & it allows me to get consistent results.

Using the tools above, I can get my collimation done as part of my setup in daylight & then just do a quick star test at the beginning of my observinig session. The star test occasionally results in me having to give the primary a teeny weeny tweak but, thus far, I've managed to get my collimation close to spot on.

Hope this helps

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