Return to the Cloudy Nights Telescope Reviews home page


Telescope Specific Forums >> Meade Computerized Telescopes

Pages: 1
Pcolon1
member


Reged: 02/10/13

BIG newbie mistake while collimating
      #5672085 - 02/10/13 10:10 AM

Hi everyone,

I purchased an LX90 GPS LNT with the UHTC coatings second hand from a guy who had every possible accessory I've read about. I've loved astronomy thus far and thought I would take a stab at figuring out collimation. With the kit he sold me was a laser collimator. I used it and noticed the laser did not bounce back onto the target. The scope already had bobs knobs so I started to try to line it up. Being a newbie I unscrewed the secondary mirror from it's cell. No worry I thought, I'll consult the Internet! I came across an article from doctor clay about opening up the tube and servicing. Big mistake. I thought I would just take the secondary out, rescrew the bobs knobs into the springs and cell and call it a night. I marked everything except for the secondary cell. The corrector plate ended up in the right position and the secondary is in the correct position in it's cell, but I don't know what position the secondary mirror cell goes in relation to the corrector plate. After 3 hours of trying to fix this I have given up. Does anyone know how to correct this? The scope now looks like it has astigmatism. Should I send to meade for repair? Any advice would be very appreciated!

Thanks,
Philip


Post Extras: Print Post   Remind Me!   Notify Moderator  
StarmanDan
Post Laureate
*****

Reged: 08/27/07

Loc: Deep in the heart of Texas
Re: BIG newbie mistake while collimating new [Re: Pcolon1]
      #5673056 - 02/10/13 08:58 PM

IIRC there should be markings made by the factory to reassemble the corrector and secondary. If not you could try rotating the secondary incrementally then reassembling and star testing each time till you get an acceptable image.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Christopher EricksonModerator
Carpal Tunnel
*****

Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: BIG newbie mistake while collimating new [Re: Pcolon1]
      #5673089 - 02/10/13 09:14 PM

Finding an expert at a local astronomy club might be useful.

https://nightsky.jpl.nasa.gov/club-map.cfm

http://www.skyandtelescope.com/community/organizations

http://www.astronomyclubs.com/

http://www.astrosociety.org/resources/linkclubs.html

The rotation of the secondary cell really shouldn't make much difference so there could be something else going on.

And a laser collimator is of limited use in a compound scope and you should be depending on a star test instead.


Post Extras: Print Post   Remind Me!   Notify Moderator  
RedLionNJ
scholastic sledgehammer


Reged: 12/29/09

Loc: Red Lion, NJ, USA
Re: BIG newbie mistake while collimating new [Re: Christopher Erickson]
      #5679706 - 02/14/13 03:08 PM

You could also potentially be mis-interpreting mega-poor collimation for astigmatism.

Grant


Post Extras: Print Post   Remind Me!   Notify Moderator  
RogueGazer
super member


Reged: 06/10/12

Loc: Central Point Oregon
Re: BIG newbie mistake while collimating new [Re: RedLionNJ]
      #5679920 - 02/14/13 05:23 PM

Quote:

You could also potentially be mis-interpreting mega-poor collimation for astigmatism.

Grant




Agreed.

Don't use a laser to collimate a SCT. Also a SCT is not like a Newtonian scope that should be collimated before each use. SCT's hold their collimation very well in between uses. Find a bright star not too low in the sky and do a star test. If you don't know how this will help....

http://www.morrell.ws/index.php?option=com_content&view=article&id=29...

Just remember to give the scope time to cool before doing it and make small adjustments at a time.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pcolon1
member


Reged: 02/10/13

Re: BIG newbie mistake while collimating new [Re: RogueGazer]
      #5686067 - 02/17/13 10:04 PM

Thanks everyone for your replies. Tonight has been the first clear night since I made this mistake and it's 12 degrees out, a bit too cold for my tastes. I called Meade and spoke with the guys at Adorama and I feel comfortable correcting this with all of your input... on some other night. This is by far the most informative forum that I've been to on the internet and it's great to be a part of it.

Should I unload the laser collimator then? It doesn't seem to have a purpose for an SCT.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Christopher EricksonModerator
Carpal Tunnel
*****

Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: BIG newbie mistake while collimating new [Re: Pcolon1]
      #5686243 - 02/18/13 12:04 AM

Quote:

Thanks everyone for your replies. Tonight has been the first clear night since I made this mistake and it's 12 degrees out, a bit too cold for my tastes. I called Meade and spoke with the guys at Adorama and I feel comfortable correcting this with all of your input... on some other night. This is by far the most informative forum that I've been to on the internet and it's great to be a part of it.

Should I unload the laser collimator then? It doesn't seem to have a purpose for an SCT.




If it has a white target area it can still be useful to you with an SCT. Do a careful star test and afterwards insert the laser collimator with the observing port facing a specific direction, like straight up or square to the left or right. Turn on the laser and see if the return laser lands on the white target area. If it does then mark the spot with a pencil, or whatever. That will allow you to do a quick check of the collimation in the future. The connection between the scope and the collimator will have to be tight and repeatable and facing the exact same way as when you marked the white target.

However SCT's rarely loose their collimation once it is set so selling it in the CN Classifieds or CN Swap & Shop is certainly an option.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pcolon1
member


Reged: 02/10/13

Re: BIG newbie mistake while collimating new [Re: Christopher Erickson]
      #5686852 - 02/18/13 11:44 AM

I guess the laser collimator was where I went wrong to begin with. The scope was collimated well and I decided to stick the laser in to see how it worked. When the spot did not bounce back and hit the side of the tube I assumed it was way off. Trying to get the back onto the target is how I separated the assembly. First one screw came all the way out and then while trying to adjust the other two to get the screw to go back in the spring fell out. The rest was a train wreck trying to get the spring back in. Is it possible that the laser will not bounce back onto the target even if the scope is collimated?

Post Extras: Print Post   Remind Me!   Notify Moderator  
Christopher EricksonModerator
Carpal Tunnel
*****

Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: BIG newbie mistake while collimating new [Re: Pcolon1]
      #5686911 - 02/18/13 12:28 PM

Quote:

I guess the laser collimator was where I went wrong to begin with. The scope was collimated well and I decided to stick the laser in to see how it worked. When the spot did not bounce back and hit the side of the tube I assumed it was way off. Trying to get the back onto the target is how I separated the assembly. First one screw came all the way out and then while trying to adjust the other two to get the screw to go back in the spring fell out. The rest was a train wreck trying to get the spring back in. Is it possible that the laser will not bounce back onto the target even if the scope is collimated?




It is very possible.

A standard laser collimator in a compound scope only bounces the laser off of the convex secondary and back to the collimator. That means that even the slightest variance in the beam hitting that convex surface can throw the return beam all over the inside of the scope. And that beam never touches the primary or the corrector plate, which are critical to any kind of meaningful collimation.

A star test uses the entire optical path and centering the central obstruction in the defocused star allows you to average all of the optical elements for the best collimation "compromise", since you can't adjust the primary or the front corrector plate.

HotechUSA has a special SCT laser collimator for $399 that looks pretty-cool but if you aren't doing astrophotography, I am not sure if you will visually see a difference between that and a standard star test collimation.

I hope this helps.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pcolon1
member


Reged: 02/10/13

Re: BIG newbie mistake while collimating new [Re: Christopher Erickson]
      #5717382 - 03/06/13 10:07 PM

I finally got a free night with a clear sky and spent about an hour collimating the thing. I purchased new Bob's knobs because I lost the spacers when I took them out the first time. In the end I'm kind of glad all of this happened because now I have more knowledge about how it works. Thanks for all the help!

On a different note now, I spent all day getting the Meade DSI to work with my netbook using Win 7 (nightmare). I got everything set up and the Autostar handbox kept shutting off but the light at the base was still on. After it turning off and realigning 3 times, the screen went black and not turn back on when I flipped the switch off then back on. I started to pack up and decided to give it one more shot in which it turned on again. Then the same thing happened. The red flashlight on top would turn on, then slowly turn off. Getting angry at an entire day and evening ruined, I picked up the entire thing and took in inside without removing the base or wedge. After 30 min I tried it again inside and turned it on. It stayed on all night without rebooting on it's own. Is the autostar 497 controller sensitive to temps below 15 degrees F?

tl;dr: Is the autorstar controller sensitive to cold weather?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Christopher EricksonModerator
Carpal Tunnel
*****

Reged: 05/08/06

Loc: Waikoloa Village, Hawaii
Re: BIG newbie mistake while collimating new [Re: Pcolon1]
      #5717733 - 03/07/13 05:06 AM

Quote:

I finally got a free night with a clear sky and spent about an hour collimating the thing. I purchased new Bob's knobs because I lost the spacers when I took them out the first time. In the end I'm kind of glad all of this happened because now I have more knowledge about how it works. Thanks for all the help!

On a different note now, I spent all day getting the Meade DSI to work with my netbook using Win 7 (nightmare). I got everything set up and the Autostar handbox kept shutting off but the light at the base was still on. After it turning off and realigning 3 times, the screen went black and not turn back on when I flipped the switch off then back on. I started to pack up and decided to give it one more shot in which it turned on again. Then the same thing happened. The red flashlight on top would turn on, then slowly turn off. Getting angry at an entire day and evening ruined, I picked up the entire thing and took in inside without removing the base or wedge. After 30 min I tried it again inside and turned it on. It stayed on all night without rebooting on it's own. Is the autostar 497 controller sensitive to temps below 15 degrees F?

tl;dr: Is the autorstar controller sensitive to cold weather?




There is a timer on the hand controller illumination that will shut off the backlight after about 11 minutes, IIRC. Pressing any button should bring the light back on.

If that isn't the issue, you might be a victim of a bad power supply or power cable connection.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
3 registered and 12 anonymous users are browsing this forum.

Moderator:  Starman27, Christopher Erickson, Starman81 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 1068

Jump to

CN Forums Home




Cloudy Nights Sponsor: Astronomics