invalid
member
Reged: 03/09/10
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So long story short, I got my first scope not too long ago but was too scared to adjust anything. The mirrors weren't really too far off so I just ignored it.
Now that the skies have cleared I decided to take a crack at it. The screw in the secondary holder was really jammed, so in the process I warped the 4 spider vanes a bit and am even more terrified to touch my baby Haha. I got things back more or less to their original state except the vanes aren't quite as straight.
Help relieve some of my anxieties! Is this a huge.problem? What do you suggest I get to help with the.process?
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BDS316
Pooh-Bah
Reged: 09/16/09
Loc: Haverhill, MA
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I speak from experience. Don't get a laser. you need a sight tube and a cheshire or a combo tool. The collimation cap can take the place of the cheshire but not the sight tube.
The trick is to remember the order, first center the secondary under the focuser, then center the image of the primary in the secondary, then and only then collimate the primary. then do not use the laser. Do a star test instead.
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joelimite
Pooh-Bah
Reged: 09/01/08
Loc: Fayetteville, AR
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I agree with Bryan's recommendation. Once I figured out how to use it, the sight tube/cheshire combo has made collimation a breeze. It's more accurate than the included collimation cap, and makes it much easier to accurately align the secondary.
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Dob Man
member
Reged: 01/15/10
Loc: Texas
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Welcome to CN,
Collimation is a technical process which you will get better at with time. The XT8 is just about a f/6 so extreme precision is not necessarily required to show decent detail on planets/lunar surface.
Start with the included collimation cap, it can get you pretty close and when you gain more experience/other collimation tools, you can always use it for a quick check.
I agree with Bryan, a laser will likely just complicate things, especially when you try to confirm the results with the collimation cap/Cheshire.
Even though your spider vanes may be a little warped, just ensure the secondary is more or less in the center of the OTA.
Next, I would do a Google search and find an easy to read collimation guide, with lots of pictures, which doesn't get too technical. It will do more justice, than one of us trying to walk you through it on the forums.
For instance:
http://www.skyandtelescope.com/howto/diy/3306876.html
Just take your time, and don’t force anything, it will get easier. 
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edadks
super member
Reged: 11/23/09
Loc: Adirondacks
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Hi and welcome to CN.
I was the same way when I got my xt8i, I was worried that if I tried to adjust anything I'd mess it up and never be able to get it working.
Turns out it wasn't difficult at all, but it does take a little bit of patience.
You might want to try to work with just the primary mirror first, that's a little more forgiving, and adjustments that you make will not have such a drastic effect. This way you can get used to how the mirror moves when you turn the screws. You probably won't get it perfect at first, but learning how the center spot moves around when you turn the screws will be a big help.
Once I did that a couple of times, I decided to jump in completely. I took the mirror out to check if the spot was centered, loosened up the retaining clips, re-installed it, then completely loosened the secondary to get it perfectly centered. After that I went back to the primary to finish the job.
Now I tend to mess around with the collimation even when it's not really out of alignment, just to tweak it.
Don't be afraid of your scope, after a couple of times you'll be telling people how to do it for themselves.
And if you really mess it up, just post a picture and you'l get help here right away.
Clear skies,
Ed
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davidc
scholastic sledgehammer
Reged: 11/24/05
Loc: Mesa, Arizona
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There is a really great article in the reflector section by Vic Menard, titled how to collimate your newtonian. That will make it easier and shed some light on the process. Get a combination cheshire/sight tube. Orion sells theirs for about $45.00, its really accurite, and has easy to understand instructions. Thats my main collimation workhorse. Star test when done, and your completed.
David
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invalid
member
Reged: 03/09/10
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Thank you for the help, guys!
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stevek
Pooh-Bah
Reged: 04/16/06
Loc: west michigan
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I am a fan of the laser method. I also use the cheshire. Cheshire to get close. Laser to do the secondary. Barlowed laser to do the primary. My laser is collimated - I collimated it myself. I can get my 8" dob collimated in under 2 minutes. A little practice and you'll get it.
Clear skies
Steve
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tedbnh
professor emeritus
Reged: 11/14/07
Loc: New Hampshire
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I'd like to put in a good word for the laser as a learning tool. There's nothing like a laser to give you the instant feedback about which way turning the screws moves things, how much the mirror tilts for each small turn of the screw, etc. It's instant feedback and good training for the beginner. Even if they graduate from the laser to the more refined tools later on, the relationships are now exposed, and can then be internalized by the immediate feedback you get watching the beam move. I think people undersestimate how important this sort of feedback is in human learning of any sort, and how much it can speed up the building of the mental model of what's going on. Once that mental model is built and internalized, you have crossed the line and can now advance into tools which work using "invisible" available light because in your mind you have saved what you learned. You can learn it without a laser of course, I just think it's easier. And why not make learning about collimation easier?
Of course, I totally agree that your "learning tool" laser better be well-collimated itself, or you are learning the wrong stuff.
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WalleyeRed
super member
Reged: 10/11/09
Loc: Central Ohio
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I have recently gone through the same thing except I had messed with the secondary and spider vane holder, but not the primary. All I had used was the collimation cap that came with the telescope. I thought I was in perfect collimation, but I just recently bought the cheshire tube from Scope Stuff. This showed me that my primary center was slightly off ,but not much for something that hasn't ever been moved in eight months. The cheshire helps you easily line up the primary center spot to the dot that is reflected from the cheshire itself. I can't recommend getting the cheshire tube highly enough. I really believe it should be included with any newt. The other thing I highly recommend for collimation is some knobs (see Bob's knobs) for your secondary tilt instead of using the tiny allen wrench which can easily be dropped right down the tube onto the primary mirror.
Also, in my experience, the Sky & Telescope collimation article (someone linked to it already above)is the easiest to understand. Just make sure you read it through entirely once then go back through it step by step. Once you do it 3 or 4 times, it is a breeze.
Regarding the spider vanes being warped...you don't want to overly tighten them, but they are pretty tough, so I have always just looked through the tube and bent them back in the direction that results in the smallest line.
Good luck and don't be intimidated because at some point, most everyone in here has gone through the same thing.
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joelimite
Pooh-Bah
Reged: 09/01/08
Loc: Fayetteville, AR
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Yes, Bob's Knobs make it much easier to fiddle with the secondary. I bought a set and they make a somewhat nerve-wracking procedure (because of the possibility of the allen wrench falling down the tube) less stressful and more intuitive. I've also seen people make their own by visiting the local hardware store, which is a cheaper route.
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Joe Lalumia
Postmaster
Reged: 01/24/07
Loc: Rockwall, Texas, USA
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I second the laser collimator-- you can collimate in just 1 or 2 minutes; especially if you have Bob's Knobs installed.
Andy has a neat video that explains BOTH methods of collimation here:
http://www.andysshotglass.com/Collimating.html
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Scott2526
sage
Reged: 04/16/09
Loc: SW Ohio
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Laser all the way!
Hand collimating (by experienced people) may lead to better overall collimation, but for most backyard astronomers a laser will get us to an very solid level quickly.
Start easy and quick. While your getting started don't make things more complicated than they have to be. This is a big reason some people loose interest.
Scott
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