How to Properly Collimate Your Telescope and Avoid Cloudy View


It is not uncommon for amateur astronomers to notice that their telescope may need a collimation correction if they come across double stars or the planets looking as though they are on top of each other.


How to Tell If Telescope Needs Collimation

The primary symptom that a telescope needs collimation is that images are blurry or distorted. This could happen for many reasons, but one of them is that the perspective within the scope needs to be aligned with both ends of the tube.

Collimate a telescope can be complicated but there are tools that make it more simple to fix. And the best part is that there are many different ways/methods to fix your telescope:

  • Without collimation tool
  • With collimation tool
  • Using an Eyepiece Method (EP)& Diagonal Method (DM)

What is collimation, basically?

Collimation is the process of aligning all of the optics in a telescope with one another to produce an accurately focused image. If your pictures are blurry, it might be time to collimate your telescope.

What is collimation? – Source: [accessed 28 Nov. 19 ]

Step 1: How to Collimate Your Telescope Without a Collimation Tool

Step 1: Find the screw on the focuser; this is typically on the bottom of the telescope.

The focuser can be found on the lower portion of the telescope. It typically is threaded and has a screw on the bottom. This screw determines how much the telescope extends from its tripod, moving the eyepiece closer or farther away. It is usually positioned near the bottom of a telescope.

Step 2: Loosen it until it’s almost all the way off.

Step 3: Turn the focuser so that it’s facing up and back toward you.

  • The focuser has three settings: the up-facing position, which is the standard-setting;
  • a down-facing position which can be used for close up photography of objects on a tabletop;
  • and a back-facing position, which is used for macro shots.

Step 4: Turn the screws on either side of this screw clockwise until they are tight – this will push out any air bubbles between your mirror and lens.

Many people are surprised to find out that air bubbles can cause their mirror and lens to not fit tightly. There are a few different ways to get rid of those pesky bubbles, but the most common is pushing them out by turning the screws on either side of the screw clockwise.

SVBONY Telescope Eyepiece
Telescope Eyepiece

Step 2- Using an Eyepiece Method (EP)& Diagonal Method (DM)

Eyepiece Method (EP) is a technique that involves taking measurements and then producing the images of these measurements on an eyepiece.

The Diagonal Method (DM) is a technique that involves measuring by finding the lengths of the diagonals from one corner to another.

The main difference between EP and DM is that an EP, we first measure before taking a picture, while for DM, we measure after taking a picture.

Collimation tool

Step 3 – How to Collimate Telescope with Collimation Tool

So to collimate telescope using a collimation tool, follow these steps:

  • 1) First, identify the type of telescope you have. There are three types of telescopes- Newtonian Reflector Telescopes, Refractor Telescopes, and Schmidt-Cassegrain Telescopes.
  • 2) Make sure the eyepiece is uncovered, and light can get in. Position it at a 45-degree angle for the ground.
  • 3) Now, place the Tool’s foot on an object that is at least as tall as your eye level. This ensures that you can keep both eyes open while performing this process. Because having only one eye available will cause double vision.
  • 4) Now, look into the hole near the foot of the Tool; use one hand to hold either side of the Telescope tube
  • and use your other hand to rotate the telescope as if you were turning a screw.
  • 5) Keep turning the telescope until you can see the light emitted from the hole in the top of the Tool.
  • 6) You may need to adjust how tightly you hold onto one side of the Telescope tube to see this light.
  • 7) What does the light look like?
  • 8) What does the other side of the collimation tool look like?

Collimation Laser

Step 4 – Do I Need Collimation Laser?

There are various reasons why you may need a collimation laser.

The first and most common reason is if you have your eyeglasses prescription. Specific prescriptions might be harder to collimate with the naked eye, and a laser will provide a more accurate result.

The second reason for needing a collimation laser is if you don’t have an eyeglasses prescription but want to wear glasses to see better close-ups. There are many different reasons why people would want these glasses.

Still, the main point here is that there are times when it’s not possible for someone without an eye doctor’s prescription to get a set of glasses as accurate as they need them to be for them to see correctly.

Step 5 – What is a Collimation Eyepiece

A collimation eyepiece is a type of eyepiece that is used to verify and correct the optical alignment of an entire optical system.

The collimation eyepiece usually attaches to the front end of an astronomical telescope, near the primary mirror or lens, and often has a small secondary mirror that is used as a reference surface for adjusting one or more components in the telescope’s focuser.

collimation cap
Collmation cap

Step 6 – How to use a collimation cap

A collimation cap is a rubberized ring that fits over the focuser drawtube to block out extraneous light. It can be put to use with telescopes of any size, but it’s most useful for larger instruments with long focal lengths.

The collimation cap will help you focus your telescope more easily by blocking out extraneous light and providing an even, controllable surface for your eye.

I have found that this tutorial is probably the best on how to use and make a collimation cap.

Conclusion: Tips on Keeping your telescope Optics in Good Shape

If you want your telescope to last a long time, you need to keep it clean and well-maintained.

The first thing that you need to do is take a look at the lens caps. If the caps are cloudy or scratched, replace them right away. This will decrease the amount of light that gets into the lens and thus reduces its effectiveness.

Next, check for any dust or other debris that may be on either end of the telescope. You can use an air blower or a brush in order to clear it off if there is any dust on it. It is also crucial to keep an eye out for moisture, which can cause significant problems with your telescope’s optics over time. The best way to avoid moisture buildup on your telescope is by storing it in a dry place.

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