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Anyone with experience collimating SW mak?

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#1 sgraffwriter

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Posted 31 December 2017 - 07:56 PM

I recently purchased a SW 150mm mak that may need to be collimated, though I have not had a night of decent seeing yet, so it’s not conclusive. I have a Celestron Omni version of C5 sct which is fairly easy to align. Is the mak as hard as some say it is to collimating? If it’s slightly out, and just needs to be tweaked, does that make the process any easier?

#2 JimFR

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Posted 31 December 2017 - 08:17 PM

Info here:

http://www.cloudynig...ak-collimation/

A couple of tips from my experience from collimating my JOC built mak. Mark one of the adjustment screws as a “don’t touch” and avoid using it, basically collimate from the other two screws, that way you don’t risk backing them off all-the-way. You still have to back off all the locking screws though to make adjustments. Second, collimate as close as you can from the front of the scope, basically peering down the tube from a distance and get the optical components as concentric as you can, then fine tune with a star test. My mak has a different screw arrangement than yours with the lock and adjustment screws in pairs rather than the staggered layout of the Synta Maks.

Very small adjustments, keep track of what your doing. It’s not hard, just takes patience.

#3 gene 4181

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Posted 01 January 2018 - 01:17 PM

  The large allen screws  are push and pull depending on which way you turn them, the little ones  (allen )  are lock screws   .    IF you haven't really  let the scope cool too ambient   your star test results will look bad , especially on the bottom of the view  , rings distorted and ill defined , especially outside focus .    Mine takes a  GOOD 2 hours too cool out    and then the star test looks pretty even  inside and outside best focus.    IF it was me , i'd use it  till you get better seeing and warmer temps unless your in CA  , FL  or other warmer  location.    Its not so much collimating it, its getting the seeing    "here "   that would concern me ,  smile.gif  ,    my star test  looks poor  until its fully cooled , no  thermal flare off the baffle  and another 30 minutes   after that the rings look even  and well defined   .     All i'm trying too convey is that in a poor location ,  (temps,seeing )   its hard to  know  exactly  IF its the scope  or the conditions  . I collimated mine without  diagonal   and used Polaris  .    GL   ,    Great scope   , problem is  its a 7in. + tube with   differing densities of air  inside  ,  warm rising against the colder  night sky side and the cold air dropping too the bottom warmer ground side  .    Hope this ain't TMI. 


Edited by gene 4181, 01 January 2018 - 01:22 PM.


#4 sgraffwriter

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Posted 01 January 2018 - 01:29 PM

Thanks for your response. I let it cool each night for an hour after keeping it in I heated Florida room. Views of moon were pretty good even though seeing was mediocre and star tests were not far off—though hard to accurately judge since seeing wasn’t good. I assumed it is/was well collimated except that front of scope doesn’t appear with concentric rings—which was the reason for initial concern.

#5 sgraffwriter

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Posted 01 January 2018 - 02:11 PM

Sorry. Meant to write “unheated” Florida room.

#6 gene 4181

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Posted 01 January 2018 - 03:00 PM

  Looking at the front of mine  for  "concentric  " rings isn't   easy  IMO   , getting the head / eye lined up  .     GL  and enjoy the scope   ,  full moon   a 40mm plossl and the mak    ,    its one of the sharpest views I've experienced  .    Good Luck and enjoy the scope  ,  and welcome too Cloudy-Nights  



#7 Phil Barker

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Posted 01 January 2018 - 03:52 PM

If the collimation is out and it was in my sw180 don't worry its easy compared to a rumak where both primary and secondary need adjusting.

 

Its easy to get confused so use one star keep the diagonal in the same position and put a mask or a line of tape over the front of the tube(won't touch correcter) to help ID which screw adjusts in a particular direction.

 

Start with lower power and finish with a higher power.

 

Unlike secondary adjustment you can be quite aggressive with the allen keys.  It took me around 10-20 minutes and its never needed adjustment.

 

needs to be cooled or stable also as that spike you get when it isn't in the defocused star can throw you off.

 

Phil 



#8 Peter Besenbruch

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Posted 02 January 2018 - 01:16 AM

To the OP: You have one of the larger Maksutovs, one where each pair of screws (big and small) are together. That makes collimation very easy.

 

Loosen the little ones by a turn or two when looking at a somewhat defocused star at 150-200x. Find the big screw nearest the off center secondary. Give the screw a 1/8 to 1/4 turn. If the star moved in the direction of the "offcenteredness," you have the right one. Recenter the star. If the miscollimation is worse, return the screw to its original position, recenter the star, and then turn the screw the same amount in the opposite direction. Recenter and check.

 

When everything is centered, tighten each small screw until you just feel them making contact. Then tighten each about 1/8 turn more to lock things.



#9 sgraffwriter

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Posted 02 January 2018 - 05:44 AM

Thanks. I thought it was easier should I need to do it. It does seem like a great scope. I started with lunar observations. It shows great detail and I was up to 250x in poor seeing. I’m happy I found this forum. I’m a public school teacher and I cover astronomy wherever possible even though it’s not part of the science curriculum. Students absolutely love it.
  • graffias79 and gene 4181 like this

#10 fcathell

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Posted 02 January 2018 - 08:33 PM

I found it's best to collimate indoors using an artificial star.  You can make artificial stars by crumpling up a piece of aluminum foil, open it back up into a wrinkled sheet, and then place it in front of a lamp with the shade removed.  The scope should be at least 30' or more from the AS. Use the smallest "stars" for alignment because the holes in the foil for them are the smallest.  Since the main mirror is being moved and not the secondary mirror as in an SCT, the procedure is opposite that for an SCT. Adjust the alignment screws (slightly!) so the defocused image moves in the direction in which the center spot is least concentric with the rings and closest to the rings. That is in the direction that would appear to make it worse.  Then re-center the image in the field and check.  Use at least 250X to do this and make sure none of the adjustment screws starts feeling lose. It takes a little practice but can be done.

 

Frank

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#11 sgraffwriter

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Posted 04 January 2018 - 10:53 AM

I will wait to collimate until I've gotten more used to the scope and used it in much better seeing conditions--probably later in the spring. By then, if I need to collimate, I'll be better prepared to follow the very helpful suggestions for how it's supposed to be done. Even with less than stellar conditions (night after night of bad to mediocre seeing), I'm very impressed with the optics of this scope. I was able to go up to 250x on a mediocre night and still see good details on the moon. Just getting outside with a telescope and seeing what's up there is amazing. 


Edited by sgraffwriter, 04 January 2018 - 10:54 AM.


#12 fcathell

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Posted 04 January 2018 - 11:42 AM

If you do have to touch up the collimation, it will pretty much stay there on a Mak.  I've had SCTs that wandered around a bit even without transportation vibration. Newts are another story altogether! I've tried all the Synta made Maks from 90mm to 150mm and they all had excellent optics.  I still have the 102 and 127 Maks and use the latter the most. I was surprised at how turbulent conditions during planetary observing affected the 127 noticeably more than the 100 despite the small difference in aperture.  It was also noticeable between the 100 and the 90mm when I had the latter.

 

Good luck.  You'll love that scope on planets and double stars.

 

Frank




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