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Collimation help first attempt


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Hi all , I thought it was about time I try my first collimation on my sky watcher 130p and I'm not sure what I'm doing wrong . I'm using a Lazer collimator ( ok not the best choice for sum) . When I first inserted the Lazer I could see that the beam was way off the center. No matter how hard I try I cannot get the beam to go dead center, the best I can get is the outer rim of the doughnut. If I try to move it closer the beam fades away .

Any ideas or help would be greatful

Thanks phil

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I'd suggest that, if this is your first go at collimation, considering doing it the 'old-fashioned' way the first time. Using either a Collimation-Cap or a Cheshire-Sighting-Tube.

Here's one of the best, well-written & lucid guides available. And we'll be here to offer you encouragement. The first-time is always a lesson in anxiety, until it all makes sense and falls into place. Then it's like riding a bicycle - easy.

From our esteemed member, Astro_Baby -

Astro Baby's Collimation Guide.pdf

Hang in there,

Dave

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Yep Dave is bang on. Also lasers can make things difficult if there is slop in the focusser. A cap and Cheshire will work better, once your secondary is set it's usually just a tweak on the primary required unless the scope gets a heavy knock.

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I just adjusted my collimation yesterday. Highly recommend that guide from Astro Baby. The first time I did it, I couldn't figure out why it looked somewhat eliptical. Low and behold, that guide explained in faster scopes like mine, that's just the way it is. Phew, wipe the sweat off my brow.

I personally use a collimation cap to align the secondary to the focuser and then I switch to my laser to align the secondary to the primary and then the primary to the focuser. I also highly recommend doing it the old fashioned way with a collimation cap or a Cheshire just to get a grasp on the concept. Lasers are great tools, but even they can be inaccurate sometimes. I would suggest that even if you use a laser, always recheck it using a collimation cap or a Cheshire. You may find that there's something wrong with your laser and that it actually requires a collimation of its own.

 

In response to bottletopburly, if your laser is making a circle on your primary when you twist it, then the laser needs to be recollimated. The spot shouldn't move.

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4 hours ago, Buzzard75 said:

I just adjusted my collimation yesterday. Highly recommend that guide from Astro Baby. The first time I did it, I couldn't figure out why it looked somewhat eliptical. Low and behold, that guide explained in faster scopes like mine, that's just the way it is. Phew, wipe the sweat off my brow.

I personally use a collimation cap to align the secondary to the focuser and then I switch to my laser to align the secondary to the primary and then the primary to the focuser. I also highly recommend doing it the old fashioned way with a collimation cap or a Cheshire just to get a grasp on the concept. Lasers are great tools, but even they can be inaccurate sometimes. I would suggest that even if you use a laser, always recheck it using a collimation cap or a Cheshire. You may find that there's something wrong with your laser and that it actually requires a collimation of its own.

 

In response to bottletopburly, if your laser is making a circle on your primary when you twist it, then the laser needs to be recollimated. The spot shouldn't move.

exactly saves collimating laser ,twist and turn centre of the circle is centre of laser :thumbsup:

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What happens is I can see the red Lazer dot on the outside of the circle , I've twisted the Lazer in the focuser and the dot stays in the same place , my issue is when I adjust the secondary mirror I can move the beam up to the outer edge of the center circle (donut) ,but then I try to move the beam to the center the beam almost disappears, but it can be see just off the center target in the collimator.

   

 

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Its been a while but I am sure you use the three screws on the back of the secondary to get the spot in the middle of the dognut, then once secure you use the screws on the back of the primary to center the spot on the target on the collimator.

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I now use a laser in a 2x barlow lens for collimating the primary mirror and it is fool proof. For the secondary, use astrobaby's guide and use coloured paper to block out the primary mirror so you can see what is going on.

It is a struggle to begin with but when you get it, it is a doddle. I have a 130pds and so I know your scope well.

When adjusting the secondary, remember you need to loosen one screw a little to tighten another one. You will be able to move the spot into the mirror by gradual adjustments, not necessarily in one large adjustment.

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There was no one more worried about undoing their collimation screws than I.  I also bought a laser first and experimented and also couldn't get it central.  Having prevaricated for about 4 weeks I finally sat down and read Astro babys guide and bought a Cheshire collimator.  Before doing the job I also watched some youtube videos.   It's well worth doing for the confidence you will gain in undoing and shifting the screws.  Just ignore how they tell you to do it and just watch them for the 'you can undo screws and get away with it lesson'.  Then follow astro baby's guide piecemeal and do absolutely everything as it is explained in order, even down to using the sheet of paper! and you suddenly see how it works.   Mine took me a good hour the first time and it is a bit fiddly as things move as you tighten them and I found I needed to play with adjustment quite a lot, but I got mine perfect in the finish and now have perfect airy discs :-)  Astro babys guide and a Cheshire worked for me and then it is fun just to dump tbe laser back in just for the fun of seeing it return bang through the centre.

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