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CPC-1100 Collimation

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#1 dallen24

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Posted 22 August 2019 - 09:24 PM

Hi.  Hope someone here could help.  Our club has a CPC-1100.  Was sitting in the box for 5 years, we've been using it for the last 3 years.  The back of the secondary plate says fastar compatible.  We've never tried to collimate it before.  Turning the inside plate quarter turn exposes the collimating Phillip screws.  All three screws are clockwise tight.  The entire secondary cap seems loose, however.  If I wiggle it I can see the secondary mirror move around.  Is that suppose to be that way?  I'm glad I didn't follow the manual and try to pop the cap with a flat-head screw driver.  I don't want to try any adjustments until I find out how the secondary is held down and how to properly adjust it.  Any advice is greatly appreciated.

 

P.S.  Just out of curiosity.  How would you use that faster cap to mount a camera?



#2 StealthPrelude

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Posted 22 August 2019 - 09:35 PM

Maybe this will help explain the Fastar/Hyperstar system. I am pretty sure collamination is just like the current manual describes the process. I also don't think the mirror should move around...
https://starizona.com/hyperstar/


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#3 dallen24

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Posted 22 August 2019 - 10:26 PM

I found these hyperstar installs https://www.youtube....h?v=GXA7X5G_Ml8 and  https://www.youtube....h?v=tcq4rBcpJak

 

Is the fastar compatible cap suppose to work the same way?  I turned the outside ring around once, but didn't seem to tighten.  The whole thing turned, could the baffle be loose?

 

Oh, sorry about the duplicate post in the other forum.  First time I ever saw this web server down and didn't know my first message posted.


Edited by dallen24, 22 August 2019 - 10:33 PM.


#4 jerahian

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Posted 22 August 2019 - 11:23 PM

I found these hyperstar installs https://www.youtube....h?v=GXA7X5G_Ml8 and  https://www.youtube....h?v=tcq4rBcpJak

 

Is the fastar compatible cap suppose to work the same way?  I turned the outside ring around once, but didn't seem to tighten.  The whole thing turned, could the baffle be loose?

 

Oh, sorry about the duplicate post in the other forum.  First time I ever saw this web server down and didn't know my first message posted.

Well, probably.  The outside ring should be able to screw down and tighten to hold the secondary mirror in place.  If it isn't then, as you say, the baffle is probably loose.  Just to be clear, are the collimation screws and the fastar label turning as well when you attempt to screw the ring down?  They shouldn't if they are.  If they are, then you might as well take it off and follow the instructions from the first video starting at time 8:49 (Checking the Corrector Alignment).

 

GL&CS,

Ara


Edited by jerahian, 22 August 2019 - 11:26 PM.


#5 ngc7319_20

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Posted 22 August 2019 - 11:25 PM

 

Is the fastar compatible cap suppose to work the same way?  I turned the outside ring around once, but didn't seem to tighten.  The whole thing turned, could the baffle be loose?

 

 

If you turn the outer ring clockwise on the secondary assembly and the whole secondary assembly goes around (and nothing tightens), then yes, the whole assembly has come loose on the glass.  There is a separate narrow ring that tightens and holds the baffle assembly on the glass.  This ring has probably come loose.  I've seen this on a Celestron C14, but I don't have direct experience with the CPC-1100.


Edited by ngc7319_20, 22 August 2019 - 11:26 PM.


#6 dallen24

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Posted 24 August 2019 - 01:23 AM

Just got back from the observatory.  I wasn't able to loosen the outside ring from the baffle.  So if we ever needed to put in a hyperstar, we'd have to first take out the corrector plate.  Which means putting it back and having to shim it.  I did look the airy disks.  The way out of focus images looked good, the secondary black dot centered.  The close to focus, however, acted like astigmatism.  Football shaped racked in, 90 degree football shaped racked out.  I do have astigmatism, but is that my eye or could it be caused by the secondary rotating around in the baffle?



#7 ngc7319_20

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Posted 24 August 2019 - 01:39 AM

Whether it is your eye astigmatism or the scope will depend on how much magnification you used.  At high magnification -- like 300x or more for this scope -  your eye astigmatism won't matter much.  I'd use something like a 6 mm eyepiece to test this scope -- that should eliminate any chance of your eye astigmatism affecting the results.

 

You can also test for your eye astigmatism by rotating your head 90 degrees relative to the eyepiece.  

 

Usually a collimation problem will show up as coma in one of these scopes -- comet shaped stars.  Not sure how to get "football" shaped stars.  Maybe if the collimation was way, way out....  Hmmm....



#8 dallen24

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Posted 24 August 2019 - 07:14 AM

It was low power, either the 2" 26mm or 20mm.



#9 Im2bent

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Posted 27 August 2019 - 09:44 PM

I bought a used Nexstar c11 and it had the same problem secondary loose I removed the corrector plate centered the secondary tightened it cleaned the inside of the corrector and closed her back up not a big deal. Here's more than you will ever want to know.As well as this video to open her up and clean .

https://www.cloudyni...tor-plate-r2476

https://www.youtube....h?v=e66yIuD3cMk


Edited by Im2bent, 27 August 2019 - 09:48 PM.


#10 Im2bent

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Posted 30 August 2019 - 06:34 PM

And also this which I did not do.

http://www.wilmslowa..._alignment.html




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