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Meade LX200 ACF 10" Collimation help please

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#1 Whichwayisnorth

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Posted 19 January 2013 - 11:19 AM

So last night has been the first time in a very long time that I had a mount for my Meade. I was finally able to get it out and look at a few planets etc. Now the problem was I noticed right away that the collimation was off. So I grabbed my handy-dandy allen wrench set and started working on it.

I would get it to the point where two of the screws were super tight while the third was still loose and yet it still needed to go further towards the two screws being tightened.

Another thing that happened is once I felt it was close I noticed that the star had about 45 degrees that was not round but kinda cut off a little.

And lastly I would get it close if you focus it one way and then it would be way way off if you focus it the other way.


My thoughts. I need to get the collimation set while focusing the mirror up against gravity, then I need lock the mirror and use a crayford forcuser thereafter.

I am wondering why the adjustments are binding where two screws are super tight but the third is loose. Maybe the center pivot point is supposed to have grease? I recall on one of my ota's back in the day there was a spring in the center. Is there a spring in the center of the CO on this model?

Looking for some advice before I proceed and make it worse.

Thanks

#2 Christopher Erickson

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Posted 19 January 2013 - 03:36 PM

Sounds like something is way out of whack and I suspect that is was a good decision to stop now before something irreversible happened.

Do you have access to any serious scope experts in your area? Local astro clubs? Local camera/optics service centers?

#3 Whichwayisnorth

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Posted 19 January 2013 - 04:01 PM

Yes I do and I think one of them has a way to center the corrector and the secondary. I bought this used and there were finger prints on the secondary bezel so I know it was apart. There are no marks to orient the secondary in relation to the corrector however the secondary will only go in one way. The problem is that the socket for it was kinda loose and you could easily spin it with your hand.

Not knowing what else to do I put a laser collimator in the back of the cell, removed the secondary, made a template out of paper and taped it over the socket hole. I wanted to see how close to center the laser was. Now this isn't perfect because the compression rings at the back don't auto center the laser but I was able to see that it may have been off a little. I think the cork along the corrector had compressed on the bottom side so I used some old wooden match sticks to re-wedge it up a little. Also like I mentioned, the secondary socket would spin pretty easily so I tightened it up so that when I put the secondary back in, one screw was up. Nothing I can do at this point other than as you say, have local experts take a look at it.

#4 starrysolace

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Posted 28 January 2013 - 12:50 PM

I have a lx200 10" ACF and I do believe the secondary has a spring behind it. While replacing my collimation screws with bobs knobs the secondary popped out of place and I had to take the whole corrector lens and secondary assembly out to push down the secondary enough to thread on the knob.

Recollimating I had a few of the knobs get tight and I was still off a bit so I tried backing those out and adjusting the lose one. I was able to get it reasonably focused. Be careful not to back out too far and pop your secondary off like I did.

#5 gaz-in

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Posted 28 January 2013 - 01:49 PM

I just collimated my 8" ACF with the Hotec CT laser Colliminator. It took me much more fiddling with loosening/tightening/etc. than my traditional SCTs to get the collimantion correct.

#6 Whichwayisnorth

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Posted 28 January 2013 - 02:46 PM

Thanks, I took it last week to Woodland Hills C&T to have them give it a shot. I don't own the Hotec Advanced Laser SCT collimator like I used to. They didn't seem to have any problems doing a indoor bench collimation but I asked them to do a star test to make sure it was working as it should. Hopefully it'll be back this week. Was expensive but I also had them clean the mirror and corrector while they were messing with it.

#7 Whichwayisnorth

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Posted 28 January 2013 - 02:49 PM

I have a lx200 10" ACF and I do believe the secondary has a spring behind it. While replacing my collimation screws with bobs knobs the secondary popped out of place and I had to take the whole corrector lens and secondary assembly out to push down the secondary enough to thread on the knob.

Recollimating I had a few of the knobs get tight and I was still off a bit so I tried backing those out and adjusting the lose one. I was able to get it reasonably focused. Be careful not to back out too far and pop your secondary off like I did.


When I took mine apart it had three springs where the adjustment screws were but not in the center. The center had a little pin that centered the secondary. I put some 3m high vac grease on it and put it back together. Figured it couldn't hurt.

#8 starrysolace

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Posted 28 January 2013 - 05:52 PM

Thanks for the info about the springs. Let me know if that solution fixes your collimation issues.






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