wikiHow to Collimate a Newtonian Telescope Spending Zero Money

No, you don't need to spend hundreds of your hard-worked money to get a good collimation for your Newtonian telescope. But of course, this may come with a price: your patience. You'll need to take some time and put great effort if you want to get good (even perfect) results. This article assumes you have some basic tools, like a pointed scissor and a Phillips screwdriver. You realize your Newtonian telescope is out of alignment if you see smudged (not blurred) images of stars and planets under high magnification, almost as if they were comets. At this point, your scope needs a collimation. If your image is simply blurred (not smudged), the problem probably is in the seeing conditions (air turbulence, halo, ice crystals in high atmosphere, etc.) or in your magnification lens; in this case, don't start messing around with collimation, or you'll find a huge pain in the neck.

Steps

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    Prepare yourself for the collimation process. You will need to be rested and your patience gauge must be full. Don't expect to do observing in the same night you start collimation if your telescope is way out of alignment, otherwise you'll rush things.
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    Build your own collimation cap: pick the eyepiece's protection cap that came with your telescope, and drill a little hole in the exact center. Remember: a LITTLE hole. You can do it using a pointed scissor. Put it into the eyepiece.
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    The first mirror to be aligned is the secondary mirror (the diagonal flat one, under the eyepiece). You realize it needs collimation if you don't see the entire secondary mirror through the collimation cap and if you don't see the three locks over the primary mirror (the concave one, in the back of the scope).
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    In most of the cases, it's not the secondary mirror that needs to be aligned (jump to step 8). So don't mess around with it unless you're certain of its misalignment! You may need to collimate the secondary if you bought the scope second hand or if you have already messed up with it.
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    If you're confused with all the reflections, block the primary mirror with a piece of white cardboard. Place a colored paper behind the secondary mirror, inside the tube of the telescope. For this step, you'll need to open your scope.
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    Align the secondary in the exact center of the image through the eyepiece: unscrew the three screws that lock the secondary mirror, and screw/unscrew the center screw to make the mirror go up/down. WARNING: keep your scope in a horizontal position, so the secondary mirror won't fall on the primary.
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    Take the piece of white cardboard off the tube. Now you need the center the reflection of the primary mirror in the secondary. Still using your homemade collimation cap, screw one of the three secondary screws, and start screwing the other two gradually until you see the three locks over the primary mirror. These locks are 120° apart from themselves, so they're easy to spot.
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    Now you need to align the primary mirror. It is a little easier then the secondary. Most new telescopes come with the exact center of the primary already marked, but if yours is not marked, you can do it by simply sticking a round piece of white paper in the exact center (take your time doing it: it must be the EXACT dead center). It won't trouble your observing as long as your piece of paper is smaller then the secondary mirror's diameter. I recommend using a piece of paper with half inch diameter (or 1 cm).
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    You need to center the reflection of your eye in the center of the primary mirror. Use the screws under the primary to do that. In most telescopes there are six screws, grouped in pairs. In this pair, one them is a locking screw, and the other is the adjusting one. Take your time to learn how they move the mirror.
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    Remember: it is the image of your eye that needs to be centered in the primary mirror, not the spider! If your telescope has what we call a "secondary offset", the spider may be off center in the final results. But don't be bothered by that if the reflection of your eye is centered.
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    At this point, your scope is ready to go for deep-sky (except binary stars) and moon observing. You may stop the collimation process here. But if you want to observe the planets in the Solar System and binary stars, you NEED to do a fine tuning in your collimation, in a process called "star test".
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    Most people pick a stationary bright star like Polaris to do the fine tuning. People in the Southern Hemisphere are not as fortunate, because finding a stationary star is way more difficult for them. But worry not: be smart! You can use any bright dot-sized light source to do the fine tuning, like antennae or far (really far) away street lights. This way you can do the fine tuning in cloudy nights and the light source is absolutely stationary. The results are the same.
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    Point your scope to your pseudo-stationary star. Use your highest magnification lens. Focus it. Now continue gradually rotating the focusing knob until you see a pattern that resembles a target (it may be off center) or a Doppler-effect illustration. If your scope is way out of fine alignment, you won't see this effect. But any slight over-focus will do the trick.
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    You need to center this target-like image. Use the screws in the back of the primary mirror to do that. Be aware that your light source will MOVE A LOT and go out of view. Keep track of where it goes so you can find it again. This process may take a few hours of trial and error, but it is rewarding.
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    If you did everything right, your Newtonian telescope is now completely collimated, and you've spent absolutely zero money. No need to buy a 50$ piece of plastic or an abhorrently expensive laser collimator (even this laser may need collimation!).

Tips

  • You can do the collimation with help from someone. It make things a lot easier and faster.
  • Spread your information sources: look for other collimation steps in the internet and see what each of them have to offer.
  • Be creative! Use your scientific curiosity to create new and easier ways to do these steps.
  • Explore your scope: definitely you won't get a perfect collimation at first try. It is a trial and error process.

Warnings

  • REMEMBER: keep your telescope in horizontal or almost horizontal position so things don't fall on the primary mirror.
  • If you are uncertain about your knowledge or your ability to handle with a high precision equipment like a telescope, DON'T DO IT.
  • Read some articles about collimation of a Newtonian before starting to mess around with your scope.

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