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Thread: Collimating a Newtonian Reflector for the first time

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    Exclamation Collimating a Newtonian Reflector for the first time



    Ok first thing's first. I understand that the telescope needs to be collimated and most people do that in the day time, but can it be done at night? I didn't expect the night sky to be so clear tonight, so I guess I put it off a day too long.

    The scope is a Celestron AVX 6" Newtonian. It has three screws on the plastic cover that protects the primary mirror. This needs to be removed, if I'm not mistaken, and the mirror needs to be adjusted so that it's centered. Then there's the secondary mirror, and that needs adjusted as well?

    Please help! And let me know if you need photos.

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    Default Re: Collimating a Newtonian Reflector for the first time

    If the skies are clear, enjoy them with the scope. Spend your first doing the collimation tomorrow inside the house with plenty of space, light, and time. No sense trying to rush it in the evening.
    Collimation is easy but the first time can be a little intimidating. It just takes patience. Once collimated, your scope may not require it for a long time. I check my collimation before every session and have not to had to collimate the dob since sometime last year.

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    Default Re: Collimating a Newtonian Reflector for the first time

    Quote Originally Posted by rickg18704 View Post
    If the skies are clear, enjoy them with the scope. Spend your first doing the collimation tomorrow inside the house with plenty of space, light, and time. No sense trying to rush it in the evening.
    Collimation is easy but the first time can be a little intimidating. It just takes patience. Once collimated, your scope may not require it for a long time. I check my collimation before every session and have not to had to collimate the dob since sometime last year.

    Like everything else in the hobby, it's a learning experience.
    You don't think the collimation will be so horribly off that it will just be a blur when I find something? Kinda like a new guitar that hasn't been tuned?

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    Default Re: Collimating a Newtonian Reflector for the first time

    Yea I agree, enjoy the views tonight. Let the little things go

    will be so horribly off that it will just be a blur
    Nah wont be a blur, more like a badmiten shuttle cock.

    If its 'blurred' you are probably out of focus.
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    Default Re: Collimating a Newtonian Reflector for the first time

    If your using a laser to collimate it, I think its easier at night. I also will check it after the mirror has had time to cool off later in the evening during a session because it may shift a little as the mirror cools. These shifts are very small, but a little tweek can help if your doing high power planetary viewing.
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    Default Re: Collimating a Newtonian Reflector for the first time

    I'm not using a laser. I'm actually just using a resource I found online (link below) to figure this out.

    The clouds ended up covering everything within an hour so I wasn't even able to see anything once I got the telescope set up and settled, so I might bother you folks tomorrow for some advice.

    In any case, to collimate the scope, here's what I understand needs done. I should point it at a tree that is somewhat far away (100 meters) and use that as a reference. Remove the protector cover for the primary mirror by unscrewing the three screws on the back and then adjust the mirror, somehow, so that the midpoint of the mirror is completely centered. While doing this I can look through the eyepiece to see how small adjustments make it better or worse. Am I right so far? And is there something that needs done to the secondary mirror?

    Here's the resource I'm currently using.

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    Default Re: Collimating a Newtonian Reflector for the first time

    If you will notice in the article it mentions all three different collimation tools, laser, collimation cap, and Cheshire/sight tube. You will need at least one of the three to collimate your scope. It can not be done correctly with just an EP and in order to test the collimation you need a star. With a tool you can collimate it during the day, but to test it you either need an artificial star or the real thing.

    In order to correctly center the secondary under the focuser you need a Cheshire/sight tube. You can eyeball it and get it close without one, but to ensure precision, you need the tube. A laser is more convenient. A collimation cap is cheap but works.
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    Cool Re: Collimating a Newtonian Reflector for the first time

    I ordered a SVBONY laser collimator at the same time as my Nexstar 130SLT. I was glad I did because two of the lock screws for the primary mirror were loose and the scope was out of alignment when it arrived. It was obvious when I tested it with the laser collimator. I watched a YouTube video about collimation, followed the instructions and found it to be a quick and easy process, even for a newbie like me. Now star testing, I have yet to do.

    I have since found out that a laser collimator also needs to be collimated because the laser might not be "straight." I placed my collimator flush with the corner of a bookshelf pointed at the wall and spun it around. The red dot was a pinpoint (not a circle) so I guess it's cool!
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    Default Re: Collimating a Newtonian Reflector for the first time

    Quote Originally Posted by Mike Bondoc View Post
    I ordered a SVBONY laser collimator at the same time as my Nexstar 130SLT. I was glad I did because two of the lock screws for the primary mirror were loose and the scope was out of alignment when it arrived. It was obvious when I tested it with the laser collimator. I watched a YouTube video about collimation, followed the instructions and found it to be a quick and easy process, even for a newbie like me. Now star testing, I have yet to do.

    I have since found out that a laser collimator also needs to be collimated because the laser might not be "straight." I placed my collimator flush with the corner of a bookshelf pointed at the wall and spun it around. The red dot was a pinpoint (not a circle) so I guess it's cool!
    I just went ahead with an old fashioned collimator cap. Just got one now. The laser collimators, apparently, tend to have those issues you mentioned with them not being properly aligned sometimes. Also, from what I read, they can mislead an amateur to move the primary mirror even further out of alignment when they should be adjusting the secondary mirror.
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    Default Re: Collimating a Newtonian Reflector for the first time

    Quote Originally Posted by Ramsey View Post
    I just went ahead with an old fashioned collimator cap. Just got one now. The laser collimators, apparently, tend to have those issues you mentioned with them not being properly aligned sometimes. Also, from what I read, they can mislead an amateur to move the primary mirror even further out of alignment when they should be adjusting the secondary mirror.
    The laser collimator has adjustment screws so it can be realigned if needed. You're right about the secondary mirror needing to be adjusted so I was able to do that first with the tool and then aligned the primary. Here's an interesting "how-to" I stumbled across, Collimate a Newtonian for zero money.

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