If you buy a Newtonian telescope you’ll need to perform a telescope collimation. What is telescope collimation? It’s a simple process used to adjust the angle of your telescope mirrors so that you have the best possible image your telescope can generate. This is something you’ll need to do periodically. If you’ve never done it, you’re probably intimidated by this process, perhaps even reluctant to buy a Newtonian telescope because of this adjustment. Don’t worry! It’s easy!
We strongly recommend that you purchase a telescope collimation tool as it makes the process a breeze. These instructions are for telescope collimation with such a tool. If you didn’t get one with your telescope, you can purchase quality one for about $100 or a cheaper one for about $65. The laser collimator featured in the image to your right is the one we recommend.
You should also be aware that there are low quality laser collimators on the market. These can be missaligned themselves and you might not notice. The result is that you’ll collimate your telescope incorectly because the laser collimator is off to begin with. If you really want to acheive optimal collimation, we recommend using the Orion LaserMate Pro Laser Collimation Kit.
Don’t feel like reading these instructions? No problem! Watch our telescope collimation video instead.
Here’s the thing with laser collimation: The first newtonion telescope I bought had instructions about collimation that were unclear. I couldn’t follow them. Then I started reading procedures online and didn’t quite understand all the diagrams. It wasn’t clear, and I found it difficult the first time. You’re in luck because I will explain the procedure CLEARLY on this page!
You need to know about three parts on your telescope. First is the hole for the eyepiece located outside your telescope tube near the end that points to the sky. Next are your two mirrors. The primary mirror is the large mirror located at the bottom of your tube. The secondary mirror is near the top of your tube (the end that points to the sky). It is small and tilted at 45 degrees in order to direct the light to your eyepiece. Telescope collimation requires the adjustment of your secondary mirror and your primary mirror, shown in the image below.
Step by Step Telescope Collimation
Tilt your telescope downwards so that it is perpendicular with the ground. You don’t want to collimate a telescope when it is upright because guess what will happen if you drop a tool or a part inside the telescope. That right, you’ll end up breaking your primary mirror and that would be a shame. Just lower your telescope angle and you don’t need to worry about breaking things.
Insert the laser collimator tool in the eyepiece hole, and twist it so that the circle with the hole on the laser collimator is pointing towards the bottom of your tube. Activate the laser.
Do not look in your telescope tube yet. Here’s why:
Your laser originates from the eyepiece hole and hits the secondary mirror at a 45 degree angle which directs the laser straight down your tube. At that point it hits the primary mirror and bounce back up. What it should do next is hit the secondary mirror again, then go back to where it started – in the eyepiece hole. However, this may not be happening. On its way back up, the laser may completely miss the secondary mirror and if you stick your head in the tube, you might get a laser beam in your eye. As a precaution, just wave your hand above the opening of your tube to see if the laser is hitting it somewhere. Always be aware of where you laser is throughout the collimation process. As you’ll be adjusting your mirrors, periodically check your laser path by waving your hand above the tube. That way, you’ll know where it is and ensure you don’t look directly at it. If the laser is not coming out the tube, then it’s likely already hitting the secondary mirror, and that’s fine. The goal is to ensure you don’t get a laser beam in your eye.
Adjusting the secondary mirror – The goal of this adjustment is to ensure that when the laser hits the secondary mirror for the first time, it is redirected to the exact center of your primary mirror. If you look down in the tube at your primary mirror, you should see a mark at the center, usually a circle. The goal is to get the laser to hit the center of this circle. How do you do this? When you look down the tube you’ll notice 3 screws just above your secondary mirror. With a screwdriver, you can tighten/loosen these to make the laser dot “move”. Adjust the screws until the laser hit’s the center of the primary mirror.
(Optional) If you can’t seem to get the laser to point at the center of the bottom mirror, start by holding the secondary mirror in your hand. Now, loosen all three screws of the secondary mirror and see if it feels loose on your hand by gently turning it back and forth. If you can do this, you’ll notice that by twisting the mirrors around you’re also moving the laser dot. If you can’t wiggle the secondary mirror around with ease, loosen its center screw a little. You want to twist the mirror until you get it as close as possible to the center. It may not go on the center directly, and that’s normal. Just get it as close as possible, and then retighten the three screws at the same rate until all three are touching the secondary mirror again. At this stage, you should be close to the center and you should be able to move the dot directly on the center by playing around with the 3 screws individually.
Adjusting the primary mirror. If you look bellow the bottom end of your tube under the primary mirror, you’ll see 6 screws. 3 of these are used to lock the mirror position and three of these are used to tilt the angle of the mirror. Start by loosening the three locking screws. Next, play with the three adjustment screws until you see the laser dot on the circle area of your laser collimator tool. Your goal is to move the red laser beam directly in the center of the circle. There’s probably a tiny hole there, and that’s where the laser needs to hit.
If you can’t see the laser dot at all on your collimator tool, that’s because the angle of the primary mirror is so off that you’re completely missing the secondary mirror. By waving your hand above the end of the tube, you can figure out where the laser is. Play with one of the adjustment screws and go wave your hand again to see which direction the laser moved. Figure out which screws need to be turned (and in which direction) to bring the laser towards the center. Eventually, you’ll get it back on the collimator tool and you can move it to the center in the hole.
Once you have it there, retighten your three lock screws to keep the mirror in this position. You’re done!
Recommended Collimator and Tools
Orion Precision Centering Adapter
Orion Collimating Eyepiece
Orion LaserMate Pro Laser Collimation Kit
Filed Under: Advice and Guides