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TAK Mewlon 210 collimation with Howie Glatter

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#1 Red Star

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Posted 26 September 2020 - 05:36 AM

Hi everyone.

 

Does any one using Howie Glatter laser collimator to collimant TAK Mewlon 210.

 

If so, would you recommend it?

 

Thanks

 

Ronnie

 

 



#2 bobhen

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Posted 26 September 2020 - 07:38 AM

I have a Mewlon 210 and see no need to use anything other than a star.

 

Even after pulling off the back and cleaning my mirror collimation was pretty close and all it took was a few minutes to get it re-collimated.

 

Bob


Edited by bobhen, 26 September 2020 - 07:39 AM.

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#3 Red Star

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Posted 26 September 2020 - 03:12 PM

Thanks for reply Bob.

 

To collimate it, gives me little bit of headache because this is all new to me.

 

I had it easy in the past, only owned refractors. 

 

I'm going to use camera to make collimation easier I guess.

 

I spent like half a night to try to collimate it and still didn't fix it.



#4 Sweep

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Posted 27 September 2020 - 06:05 AM

I’m having a similar problem with the Howie Glatter and a vixen vmc 260l.

My initial problem is collimating a moonlight focusser not sure what to do.

Watched a Stephen Kirk video but focusser was a different type?



#5 Nippon

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Posted 27 September 2020 - 07:15 AM

The collimation instructions that came with my u180 are intended to be done with an eyepiece straight through. I found it quite easy to collimate following Takahashi's instructions. When I first checked it straight through it looked perfect right out of the box. At high power I got perfect Airy disks with or without a diagonal. Stars out of focus however with the diagonal looked off so I decided to fine tune it with the diagonal and that destroyed the view with or without the diagonal. So I recollimated straight through and it again gave me perfect Airy disks. What I determined is with a Mewlon if you view a star even slightly off center the ring pattern out of focus looks off so I think it's best to collimate the scope itself and unless your diagonal, camera Etc. is way out of alignment with the scope things should look good.


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#6 bobhen

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Posted 27 September 2020 - 07:59 AM

Thanks for reply Bob.

 

To collimate it, gives me little bit of headache because this is all new to me.

 

I had it easy in the past, only owned refractors. 

 

I'm going to use camera to make collimation easier I guess.

 

I spent like half a night to try to collimate it and still didn't fix it.

Use a star. If you don’t have a tracking mount use Polaris

 

ALWAYS keep the star centered. After you make an adjustment, re-center the star.

 

Try and pick a night of at least decent or good seeing.

 

You should only need to make 1/16 to 1/8 inch turns on the screws. If they squeak that is OK.

 

Use powers of at least 350 or more.

 

HERE is a YouTube link that might help. He uses an an SCT and an artificial star but the procedure is just the same.

 

Bob


Edited by bobhen, 27 September 2020 - 07:59 AM.


#7 dusty99

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Posted 27 September 2020 - 09:51 AM

That’s a fine video for achieving rough collimation in an SCT, but unless you’re very lucky it won’t get you to the sharpest images at the eyepiece (I have come to suspect that the majority of complaints about lack of critical sharpness of -at least contemporary- SCTs is due to users not collimating completely).  To fully collimate an SCT you would follow up the instructions in the video by continuing to focus closer and closer to best focus and correcting for any out-of-round image shown in the now slightly defocused, perfectly-centered star.  As bobhen posted, higher magnification is necessary, which can be an issue if your typical seeing conditions won’t allow.  You may have to get it close then wait for a calm night to finish. It seems this also applies to Mewlon collimation, and some owners think it’s a more complicated process than others acknowledge:

https://astromart.co...-a-mewlon-55542

 

Takahashi includes instruction for both rough and fine collimation in their instructions:

https://www.telescop...n_manual_EN.pdf

 

Don’t be put off, though.  Once you’re familiar with the process it should be easier, and I assume the higher build quality of the Mewlon will help the small secondary adjustments be more consistent than is the case with a mass-market SCT (the very small (< 10 deg.) turns I have typically finished fine collimation with on my three SCTs aren’t so consistent, likely thanks to lower tolerance of the threads of the screws or secondary mirror mount).  Good luck!

 

 

HERE is a YouTube link that might help. He uses an an SCT and an artificial star but the procedure is just the same.

 

Bob

 


Edited by dusty99, 27 September 2020 - 09:55 AM.


#8 Red Star

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Posted 30 September 2020 - 07:24 AM

Thanks everyone for their good advice.

 

I did it and it wasn't so difficult. 

 

I did it during day time from the instructions Viking 1 supplied in one of those links. 

 

I just used carboard. 

 

I wrecked the collimation hips but now its very, very close. 

 

I will follow Bob's instruction once I'm out  on the star to fine tune it.

 

I don't think I can wreck it again, I kind of understand the process.

 

Thanks a lot again, everyone. 




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