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Intes Micro MN66 mak newt collimation help!

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#26 Tyson M

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Posted 15 December 2018 - 01:41 AM

Tyson, I have collimated about three of these scopes. The first thing to know is that the secondary is minimally sized for keeping the CO small. What results from this is that there is vignetting at field periphery. This will show as out of round fresnel patterns toward field edge. With my MN-66's this started almost the moment the star was off center. So bear this in mind when collimating.

Secondly, the M-N is different from a plain Newtonian in that, in the Newt, the aperture stop is at the primary mirror while in the M-N, it is at the corrector. Consequently, focuser tilt is not tolerated as it's not possible to tilt the corrector. The primary-secondary-focuser optical axis has to coincide with the corrector axis as well.

I would start collimation with first making the secondary as parallel to its holder (screwed into the corrector) as possible. Then adjust the focuser up/down (the better M-N's have this adjustment) till the secondary is centered (but may present as oval). Next rotate the secondary by first loosening its retaining ring. There is a tiny set-screw in the retaining ring which has to be loosened first. Once you have a circular looking secondary in the focuser, you can proceed with the usual Newt collimation steps, iterating if necessary. My primaries had all a plug in the center so I could never use auto-collimation, but using a cheshire, I could successfully collimate them to perfection.

Since these are fairly short focal length scopes, using an artificial star, with extension tubes for the eyepiece (I used barlows with optics screwed off), will be a good idea to check the final primary collimation.

Finally remember that I-M offsets the secondary a bit so it may not look centered after final collimation.

Good luck,
Tanveer.

EDIT: fixed typos

I just checked this out with the astrosystem's combination tool. Everything looks really good. I think this may be vignetting, that is only noticeable at higher powers?

 

I didnt see any light fall off with a Pentax 40 XL EP, or 27 pan.  Just the 10 Pentax and above, right after the star gets off center. 



#27 Tyson M

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Posted 15 December 2018 - 01:09 PM

I think the 70 degree AFOV is a tad too much.

 

62-68 AFOV is likely the sweet spot with this secondary.



#28 Jeff B

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Posted 15 December 2018 - 10:29 PM

Mike, I'm curious.  Some of the Intes MN's were specifically set up for imaging.  When done so, a spacer tube was necessary to use it visually.  Do you have to use a spacer tube?

 

The reason I'm asking is that while the secondaries are small, they still offer a decent fully illuminated field, maybe 6-7 mms, when set up for visual use.  While tight, you should have no trouble seeing the entire primary with a little room to spare in the sight tube.   

 

Jeff



#29 Tyson M

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Posted 15 December 2018 - 11:45 PM

Mike, I'm curious. Some of the Intes MN's were specifically set up for imaging. When done so, a spacer tube was necessary to use it visually. Do you have to use a spacer tube?

The reason I'm asking is that while the secondaries are small, they still offer a decent fully illuminated field, maybe 6-7 mms, when set up for visual use. While tight, you should have no trouble seeing the entire primary with a little room to spare in the sight tube.

Jeff


No spacer tube, and using the astrosystem sight tube I can see the full primary mirror with just the slightest space around it. I am still learning on using it, but it appears that everything is lined up.

It appears to not have vignetting with 40xl eyepiece. Or 27panoptics.

#30 TG

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Posted 16 December 2018 - 02:54 PM

No spacer tube, and using the astrosystem sight tube I can see the full primary mirror with just the slightest space around it. I am still learning on using it, but it appears that everything is lined up.

It appears to not have vignetting with 40xl eyepiece. Or 27panoptics.


A sight tube will not show you vignetting that's asymmetrical since the peephole is centered. What you'd need is a tube with an off center hole. If you can't see parts of the primary from such an off center hole, the you'll obviously have vignetting.

#31 Denny955

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Posted 20 March 2019 - 04:48 PM

Hello,

 

I've been reading up on collimating the Intes Micro Mak Newt here from last December. I have an 8" f4 IM  that I need help collimating. I bought it used several years ago and got some great pics thru it but I think the 2500 mile trip from PA to New Mexico in 2013 knocked it out a bit. I did the rest by trying to collimating it without an instruction book. (still never found a book)   Didn't realize how easily the secondary would flop down when trying to adjust it and didn't know how to get it back in position without pulling the corrector plate.   So the big question for me is what happens when you don't get the paper thin shims back in place.  Mine pretty much disintigrated when I pulled out the corrector plate. They looked like old pieces of dried up newspaper!!!  (I did mark the position of the corrector with the tube) 

 

I've always thought that the focuser might have been out of kilter but have no good way of measuring that unless I take the corrector back out along with the primary. I've adjusted it the best I could by using the reflection of the secondary in the primary using a laser collimator...not an easy task when trying to not get flashed by the laser.

 

I thought I had it collimated last year but when I zoomed in on the stars in my pics they still had a small chunk out of the one side.  Also the stars are not round along the edges like they use to be. I've done much of what was recommended on here, even purchased a lazer collimator to help out with the collimation. I made and used an artificial star so I could work during the day to see what I was doing. That was a big help.  Just had to do a little tweak at night to get the consentric rings spot on. 

 

 Anymore suggestions will be greatly appreciated. I love the scope and would like to get it back in service!

 

Thanks

Denny



#32 coopman

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Posted 20 March 2019 - 06:55 PM

Does ypur scope have the stock focuser on it?  I replaced that thing as soon as I got mine.  It was like the leaning tower of pisa!  Mark at Teton Telescopes told me once to never loosen the center bolt on the secondary unless I wanted a real fun time getting it collimated back again.  I heeded his advice.  I think that there was at least one real good old thread here about collimating MNs.    



#33 Paul Hyndman

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Posted 20 March 2019 - 08:27 PM

It’s been many many, moons since I’ve tinkered with my MN86 but about a dozen years ago I plonked a quick “how I do it” article here on CN which may (or may not frown.gif ) have a few things that might be of help.

 

My two cents (overpriced?)

 

https://www.cloudyni...procedures-r389



#34 Denny955

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Posted 22 March 2019 - 01:38 PM

Thanks for the reply and tip. My scope has a Feathertouch focuser on it so if that's stock I was never impressed. Plus it has a motor focuser and I needed to buy the high priced controller to run it.  Also, the heads of the tiny adjustment screws always strip out plus the focus knob has to be removed to get to the screws underneath making collimation very difficult with everything being loose.

Being I bought this used I have no idea what these went for new. I know all the used ones I  checked out we're around the same priced. Plus the rotating rings on mine are sweet! I know they go for at least $600. 

I'll read over the article again when I get home and see if there is anything that I missed or can do differently.
Denny




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