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Mike N.
member
Reged: 04/30/07
Posts: 23
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All,
I hope that you can help me with this issue. I have a 10" Meade LX200GPS. At the end of last year, I was seeing that my clarity was off and I knew that I needed to collimate it.
I purchased a Kendrick SCT laser recently, and have had nothing but problems getting things to work. Stars are no longer slightly blurry, they are now blobs. I also have Bob's knobs.
I worked at this for many hours so far and this is what I am seeing/doing.
1) I place the target at approx 50 feet, so I can get the beam to be approximately 1/4" in diameter. To accomplish this, I need to focus out 100% clockwise.
2) I start with an reticle eyepiece and center the crosshairs on the provided target.
3) I place the laser into the scope and adjust the knobs so the laser is about a quarter of the difference toward center of the target.
4) I place the reticle eyepiece back in and then adjust that back a quarter of the difference toward center of the target.
This now places the laser in about the same position it was when I started. I can this 30 times and still have the same result.
My scope is so far off at this point, I am not sure what to do. I am thinking of taking this to the shop that I purchased it and see if they can do it professionally. I would rather not do this and actually learn what I may be missing.
PLEASE HELP!
Thanks,
Mike
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Meade LX200GPS 10" SMT
Meade ETX-90RA
Meade ETX-70AT
Canon EOS 30D DSLR
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Joe Lalumia
Post Laureate
Reged: 01/24/07
Posts: 3600
Loc: Rockwall, Texas, USA
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Your problem is the LASER, stop using it.
Instead get a 2nd mag star and use this technique to collimate.
http://sctscopes.net/SCT_Tips/Maintenance/Collimation/collimation.html
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LX90 8" LNT, SV Nighthawk & TelePOD, SV 80/9D & M4 mount, ETX 90, Orion XT10i, 20x80 binoculars, SV-BV3s-- www.texasastro.org
"Great minds discuss ideas;Average minds discuss events;Small minds discuss people." Unknown
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Bob Griffiths
Postmaster
Reged: 10/10/05
Posts: 6552
Loc: Frederick Maryland
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Quote:
Your problem is the LASER, stop using it.
Instead get a 2nd mag star and use this technique to collimate.
http://sctscopes.net/SCT_Tips/Maintenance/Collimation/collimation.html
I absolutely AGREE.... COMPLETELY !
Bob G.
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Mike N.
member
Reged: 04/30/07
Posts: 23
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If all I have currently is the laser, and want to know how to do it with that, has anybody used it that can tell me what I am doing wrong?
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Meade LX200GPS 10" SMT
Meade ETX-90RA
Meade ETX-70AT
Canon EOS 30D DSLR
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Joe Lalumia
Post Laureate
Reged: 01/24/07
Posts: 3600
Loc: Rockwall, Texas, USA
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You need ONLY your eyes. Take the scope outside and get it tracking on a medium bright star Polaris would be good.
First defocus the star until you get a donut shape in the eyepiece. CENTER the dark spot as best you can using small turns of the bob's knobs. RECENTER the star after every adjustment.
Once the donut looks OK. SLIGHTLY defocus the star and see where the center (secondary) shadow falls. Again very slight adjustments to try and center the secondary dark spot. Use a 20mm eyepiece for the first rough adjustment, then use a 9mm or 8mm eyepiece for the second adjustment.
5-10 minutes of work.
OK folks where is that link I posted that shows which way to turn the Bob Knobs or allen screws. ????
OK I found it again- http://home.comcast.net/~astrophoto/Articles/Collimation.htm
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LX90 8" LNT, SV Nighthawk & TelePOD, SV 80/9D & M4 mount, ETX 90, Orion XT10i, 20x80 binoculars, SV-BV3s-- www.texasastro.org
"Great minds discuss ideas;Average minds discuss events;Small minds discuss people." Unknown
Edited by Joe Lalumia (10/16/09 11:04 AM)
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MarkLX90
member
Reged: 04/07/09
Posts: 57
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You can rough collimate using them, but that's it..
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Bob Griffiths
Postmaster
Reged: 10/10/05
Posts: 6552
Loc: Frederick Maryland
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Quote:
If all I have currently is the laser, and want to know how to do it with that, has anybody used it that can tell me what I am doing wrong?
If I had to take the trash out I sure would not drive the pickup truck into the back yard and load the trash can in the back of the truck then drive out to the curb... Actually would take more time effort then just walking the can down to the curb..as well as costing a hair more...shoe leather is cheap !
Seriously I have NEVER HEARD of ANYONE who has EVER USED any piece of Equipment like your laser to collimate a SCT AND who though it was a worthwhile purchase...
Throw the laser out then you will not have anything to collimate the scope with but your eyes
...no fuss no muss...
If these things worked almost anyone who owned a SCT would definitely own and use one...
Bob G.
Sorry if the tone of this post seems harsh..It was not intended to be...
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CPC1100
Nexstar 8i + GPS & Rays Brackets
Denk S1 power switch
Orion 100 mm Refractor
Meade LXD 55 ...AR-5 127 mm Refractor
Exploradome Observatory S.I.E. (Smiling Irish Eyes)
Gerbring Heated Motorcycle clothing in the winter
39*21'03" N
77*28'12" W
The sky over my head....
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Mike N.
member
Reged: 04/30/07
Posts: 23
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Thanks all for the replies and I do mean that.
I just didn't want the answer I knew I would get about how not to use them and there are better ways. This I kinda of already knew. I wanted someone that has used the lasers before, to give me some experience with them and things I should be seeing.
Again no offense to anyone that responded.
Thanks,
Mike
--------------------
Meade LX200GPS 10" SMT
Meade ETX-90RA
Meade ETX-70AT
Canon EOS 30D DSLR
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deleterman
super member
Reged: 03/13/09
Posts: 145
Loc: san diego,ca
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Very good,I have been thinking of collimating my XL200 got it in 1994. works like a champ, but it's have only beem collimated one about 10 years ago,I'm just about ready to get a new diagonal so i will kill two birds at the same time.that guide by Steve Walters looks great.went and got some Bobs Knobs . I'M to old to use those hex head wrenches and in the dark !!? can't wait to get that done.also going to check and see if i need to regrease the gears..BTW any thoughts on the type of grease ? i think i read some thing about Harbor Freight has Lithium super lube.is that good ?well thanks .H.B.
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scopethis
professor emeritus
Reged: 05/30/08
Posts: 619
Loc: Kingman, Ks
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Golly, not very often, but I still use an ole Celestron MFFT--or the Multi Function Focal Tester-55--close enough!
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deleterman
super member
Reged: 03/13/09
Posts: 145
Loc: san diego,ca
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what does that mean?
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quantumac
sage
Reged: 12/17/07
Posts: 385
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I collimate whenever I alter the imaging train, and I casually check collimation whenever I start the first imaging run of the evening. Realize this comment comes from someone who has an observatory, where the telescope is permanently mounted. Collimating becomes even more necessary if you move the telescope around (like most users do).
Collimation for SCTs is critical to good imaging and good viewing. It's actually easier to collimate if you are imaging, because you can use your CCD to display what the scope sees on your computer screen. Collimation then becomes an exercise of standing near the business end of the scope, making adjustments to the collimation screws and re-centering the star in your computer screen.
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Scope: Meade 10" LX200R
Guide/Planetary Camera: Imaging Source DBK41AF02.AS
DSO Camera: QHY8
Guide Hardware: Celestron OAG, Shoestring Astronomy GPUSB
Software: Mac OS X, Starry Night Pro, Nebulosity, PHD Guiding, PixInsight, Astro IIDC. No Windows anything.
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Mike Harvey
professor emeritus
Reged: 03/01/04
Posts: 692
Loc: Orlando, FL.
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That laser dot can be well off from the actual optical alignment!
The return is subject to mechanical misalignment too.
Since we only have control of the secondary (and, to a lesser extent, the corrector plate and focuser) there's little we can do about a slight factory misalignment of the primary (or even the secondary's centering on the corrector plate).
That's usually not a major impactor on performance as long as you're optically collimated.
But, if you 'chase' that laser dot with the secondary adjustment screws, you can easily have it "mechanically aligned" but "optically" waaaay off.
I've just "returned" to SCT ownership after 20+ years without one.
Fortunately, during those years I've used larger and faster Newtonians (see my icon) and have, consequently become comfortable with collimation (and actually learned a few things along the way!). 
You simply cannot collimate an SCT with today's laser techniques. HoTech is bringing a new product to market that may change this, but, that's in the future.
So far, the best method I've found (other than the actual star test) is the 'artificial' star. The biggest benefit of this is that it is not "seeing limited".
You ALWAYS see the diffraction rings without any distortion or 'breaks'...and each ring is brightly illuminated. This makes secondary collimation quick, easy and certain.
As a side-note: My new Meade 10"LX200 ACF came with SIX adjustment screws on the secondary! I don'tknow if this has been done for a while, or is a new feature of the ACF's...but it's sure a welcome addition.
The 'extra' three screws LOCK the secondary in place after collimation.
My scope arrived PERFECTLY COLLIMATED after several days, and over a thousand miles, of the shipping company's "tender, loving care".
Mike
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quantumac
sage
Reged: 12/17/07
Posts: 385
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The Meade 10" LX200 ACF has THREE adjustment screws. The other three screws are to hold the secondary mirror in place and should not be adjusted.
--------------------
Scope: Meade 10" LX200R
Guide/Planetary Camera: Imaging Source DBK41AF02.AS
DSO Camera: QHY8
Guide Hardware: Celestron OAG, Shoestring Astronomy GPUSB
Software: Mac OS X, Starry Night Pro, Nebulosity, PHD Guiding, PixInsight, Astro IIDC. No Windows anything.
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