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

Moderately Priced Laser Collimator

  • Please log in to reply
5 replies to this topic

#1 patindaytona

patindaytona

    Viking 1

  • -----
  • topic starter
  • Posts: 610
  • Joined: 09 Aug 2019

Posted 09 October 2019 - 12:42 PM

I went thru a couple weeks of collimating a while back. I am pretty sure my optics are good. I used a cheap chesire, but it never got perfectly aligned(cross hairs), but pretty close. Some reason, if i aligned it correctly, I'd always end up with mis-alignment of the concentrics (even the primary mirror was clipped).

 

Probaby due to the cheap collimator. I don't know for sure though.

Since I can't afford much, I still have a moderate price range of a collimator in mind. It the Zhumell 1.25" Laser Collimator for $50 on Amazon.

On another site, the description said that "do not adjust the adjustment screws on it, or it may not work right". It says it comes already aligned. One customer review said that it was way off when he recieved it.

Thing is, I don't like messing with things like this. I had a cheap laser collimator that came with my used Orion XT10i and i stripped the screw on it.

I don't want to do that with something more expensive. So I'm thinking, if it isnt' right, send it back until they give me an adjusted one. I don't know how dependable that will be since most come unadjusted.

What do you think?



#2 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42724
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 09 October 2019 - 01:19 PM

Inexpensive lasers are basically cat toy lasers mounted in an external aluminum shell.

The internal supports are not strong enough to stay collimated if the body of the laser receives a shock,

so even if it is perfectly collimated on the shelf, there is a high probability it won't arrive at your house collimated

after being shipped.

So, if you don't want to collimate the laser when you get it, you will confine yourself to the better lasers out there:

Howie Glatter, Farpoint, Astrosystems.

 

For your price point, I'd simply stay away from lasers altogether and get a good Sight tube/cheshire combination tool instead.

 

Or, reconcile yourself to the idea you will have to collimate the laser when you get it. 

It's really not that hard, and if you don't drop it afterwards, it will likely stay collimated.

 

Here are some simple instructions showing how to collimate a laser:

http://www.stark-lab.../llcc/llcc.html
http://www.astromart...p?article_id=96
http://www.cloudynig...collimator-r509
http://www.visualast...collimator.html

Use whichever one seems clearest to you in its explanation of what to do.

 

Your comment about the primary mirror being clipped says that after you collimated using your tool, it revealed the secondary mirror was too high or too low and not centered under the focuser.

If you encountered that after collimation, then the secondary should have been moved.  You don't miscollimate just so the entire primary is seen, you move the secondary and

collimate again and keep repeating until the entire primary is see in the secondary at the same time the tool shows both mirrors are collimated.

A laser, by the way, doesn't escape this problem.



#3 patindaytona

patindaytona

    Viking 1

  • -----
  • topic starter
  • Posts: 610
  • Joined: 09 Aug 2019

Posted 09 October 2019 - 01:27 PM

Inexpensive lasers are basically cat toy lasers mounted in an external aluminum shell.

The internal supports are not strong enough to stay collimated if the body of the laser receives a shock,

so even if it is perfectly collimated on the shelf, there is a high probability it won't arrive at your house collimated

after being shipped.

So, if you don't want to collimate the laser when you get it, you will confine yourself to the better lasers out there:

Howie Glatter, Farpoint, Astrosystems.

 

For your price point, I'd simply stay away from lasers altogether and get a good Sight tube/cheshire combination tool instead.

 

Or, reconcile yourself to the idea you will have to collimate the laser when you get it. 

It's really not that hard, and if you don't drop it afterwards, it will likely stay collimated.

 

Here are some simple instructions showing how to collimate a laser:

http://www.stark-lab.../llcc/llcc.html
http://www.astromart...p?article_id=96
http://www.cloudynig...collimator-r509
http://www.visualast...collimator.html

Use whichever one seems clearest to you in its explanation of what to do.

 

Your comment about the primary mirror being clipped says that after you collimated using your tool, it revealed the secondary mirror was too high or too low and not centered under the focuser.

If you encountered that after collimation, then the secondary should have been moved.  You don't miscollimate just so the entire primary is seen, you move the secondary and

collimate again and keep repeating until the entire primary is see in the secondary at the same time the tool shows both mirrors are collimated.

A laser, by the way, doesn't escape this problem.

It's difficult to explain. After collimating with laser, the primary was clipped. And i did move the secondary several times to account for it. And still, the primary would be clipped after using the laser. It was a tug of war between collimating the laser adjustment vrs the concentric adjustments using the peep hole cap. When I used the cap, and concentrics were as good as i could possibly get. The laster cross hairs would then end up being far off center. It just didn't end. I'd try to move the secondary every time and ended up the same way. The two different adjustments just never aligned wIth each other. But, I did manage to get the cross hairs very close eventually while maintaining a concentric alignment.


Edited by patindaytona, 09 October 2019 - 01:28 PM.


#4 wrnchhead

wrnchhead

    Apollo

  • *****
  • Posts: 1012
  • Joined: 28 Aug 2017
  • Loc: NE Kansas

Posted 09 October 2019 - 01:29 PM

+1 on Mr. Pensack's comments about collimating your own laser. It is not difficult. I imagine you stripped the screw in your other one possibly due to not understanding how its set up. As he said, there is basically a laser pointer inside the aluminum tube and those three screws come in and hold it 120 degrees apart. If you tighten one too much without loosening the others, you may exert too much force on the captive laser pointer. 

 

I have had good luck with my cheapo GSO one. I personally have yet to be sold on a $300 laser pointer, but I am definitely no optics expert. 



#5 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42724
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 09 October 2019 - 02:27 PM

It's difficult to explain. After collimating with laser, the primary was clipped. And i did move the secondary several times to account for it. And still, the primary would be clipped after using the laser. It was a tug of war between collimating the laser adjustment vrs the concentric adjustments using the peep hole cap. When I used the cap, and concentrics were as good as i could possibly get. The laster cross hairs would then end up being far off center. It just didn't end. I'd try to move the secondary every time and ended up the same way. The two different adjustments just never aligned wIth each other. But, I did manage to get the cross hairs very close eventually while maintaining a concentric alignment.

That wouldn't have been the case with a collimated laser that fit the focuser properly if the secondary was correctly positioned.

What you are describing is a classic case of a miscollimated laser.


  • wrnchhead likes this

#6 patindaytona

patindaytona

    Viking 1

  • -----
  • topic starter
  • Posts: 610
  • Joined: 09 Aug 2019

Posted 09 October 2019 - 04:09 PM

That wouldn't have been the case with a collimated laser that fit the focuser properly if the secondary was correctly positioned.

What you are describing is a classic case of a miscollimated laser.

Glad you agree. I thought same thing. I was just RE-collimating past few hours. Might have gotten the collimater to match the concentrics a bit better. Every bit helps.

Will check it on a star when clouds clear, but Im sure it's good. I did find out today that the 1.25" adapter that fits into the 2" has some wiggle (i guess everyone calls it slop). So, that's some there, and i tried scotch tape and took care of that, but their's some in the actual laser too. And on top I think it's just miscollimated like you say. It's actually a cross-hair chesire. Cheap one.

I turn it and see it's off, not a huge amount but enough.

In the end because the screw that tightens the eye piece in, causes it to tilt (another thing), will try to remember to use that screw on bottom so that whenever I put an eye piece in, it pushes UP the eye piece just enough to cause the best alignment I can get out of it all. (tried that with the chesire and saw it causing the "correct" tilt). With these different variables, I suppose it's about as good as i can get it.

I'm not real familiar with various collimators, but this seems pretty long to me. Maybe that answers some questions here.

Attached Thumbnails

  • aaa.jpg

Edited by patindaytona, 09 October 2019 - 08:24 PM.



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