Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

2" /1.25 " focuser collimation

  • Please log in to reply
5 replies to this topic

#1 bowersox1

bowersox1

    Lift Off

  • -----
  • topic starter
  • Posts: 20
  • Joined: 14 Aug 2020
  • Loc: Lewisburg, Pa USA

Posted 30 September 2020 - 09:25 PM

Had a chance for about 45 minutes tonight to view the moon till clouds came over. The views through the EP have been ok. I know or almost know my primary mirror needs washed and that will be happening in the next 3 weeks. I got batteries for my Lazar collimation tool. It's a 1.25" barrel. When i put it in the focuser it was off center. But if i turn the tool the dot moves around. I also noticed that if i loosen the 2 to 1.25 inch adapter it chances the dot's position. it can change it from one side to the other. Is this normal and if this is the nature of the beast how can i get the scope collimated closer and not change with every EP? The scope is a XT8 cray-ford focuser with the original 2" to 1.25" adapter.



#2 Couder

Couder

    Messenger

  • *****
  • Posts: 459
  • Joined: 24 Feb 2014
  • Loc: Missouri Ozarks

Posted 30 September 2020 - 10:08 PM

We solved that problem with paper shims around the laser where it goes in the holder. We got it just tight enough that when we rotated it the dot remained in the same place. You do need to have the focuser square with everything. To test the laser put it on something with a "V" shape and rotate, (Maybe a vise in the garage open just enough to keep the laser from falling) that will tell you if it is the problem, or one of the problems.



#3 wrnchhead

wrnchhead

    Vanguard

  • *****
  • Posts: 2,430
  • Joined: 28 Aug 2017
  • Loc: NE Kansas

Posted 30 September 2020 - 10:47 PM

Sounds like the laser is almost certainly out of collimation. There will be three Allen set screws on the sides to collimate it. Inside it is basically a laser pointer held solidly in the front, and you angle the back with those screws. Figure out what direction you need to move it, then loosen one or two and tighten the opposite. Basically you don't want to overtighten it, it's being squeezed by them. Repeat until it doesn't form a circle in the v-block. A distance of ten feet or more. More is better. First time this may be a little frustrating. Be patient. 

 

Unless the focuser is wildly sloppy (they all have some clearance) I just use a consistent method to tighten it and then the eyepieces in use. 


Edited by wrnchhead, 30 September 2020 - 10:54 PM.


#4 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 87,296
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 30 September 2020 - 10:49 PM

It is likely your laser is out of collimation as well as being a sloppy fit.

 

There are instructions for collimation your laser on the web.

 

Jon



#5 bowersox1

bowersox1

    Lift Off

  • -----
  • topic starter
  • Posts: 20
  • Joined: 14 Aug 2020
  • Loc: Lewisburg, Pa USA

Posted 30 September 2020 - 11:22 PM

We solved that problem with paper shims around the laser where it goes in the holder. We got it just tight enough that when we rotated it the dot remained in the same place. You do need to have the focuser square with everything. To test the laser put it on something with a "V" shape and rotate, (Maybe a vise in the garage open just enough to keep the laser from falling) that will tell you if it is the problem, or one of the problems.

I did verify the laser using the V block at 10 feet. It was close that my eyes couldn't tell a difference.


  • wrnchhead likes this

#6 hakann

hakann

    Vanguard

  • -----
  • Posts: 2,141
  • Joined: 06 Aug 2015

Posted 01 October 2020 - 07:51 AM

The slobby fit is well know deal.

Many talking about high tolerance but plano mirrors sag, create heat, weak chasies, seeing issues etc so if a star is Ok, it is, that's the way I see it.

One I know in Oregon set up his fast scope and installed a old laser and checked out the secondary then it was about the stars and it was ready.

He mean if a steady cell primary do not move.

Guess it's call experiance how to deal with a sitiuation. 


  • wrnchhead likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics