How to Collimate Binoculars? Terminology and Step-by-Step Guide!

In this article, we teach you how to collimate your binoculars in just six simple steps so that you can enjoy the best possible viewing experience.
James Harper
James Harper
Research Writer
Being a professional journalist, James knows how to turn any topic into a comprehensive, easy-to-digest text. Even if you've never dealt with telescopes before, rest assured read more
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Charles Goebel
Charles Goebel
Expert Consultant
Charles holds a Master’s degree in Physics Engineering (optics and photonics specialization), has been teaching physics at school for almost 15 years and recently has star read more
Last updated: August 15, 2023
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Do you see double images on your binoculars? If yes, don’t get excited that you have discovered a new place; because all you can see is actually one image. This double vision indicates that your equipment is out of collimation. It would be best if you learned how to collimate binoculars so that you can fix the issue.

Collimation is a process by which manufacturers systematically align your binoculars’ lenses and other components to bring images to their perfect focus. When you mishandle the equipment, you might cause its prisms and lenses to misalign and go out of collimation, making you see two different images. Such a piece of optical equipment that has double vision is deemed to be useless. You cannot differentiate two objects using it or precisely focus on any spot.

Fortunately for you, collimating your binoculars isn’t rocket science. You can do it yourself with ease and within minutes. In this article, we’ll show you step-by-step instructions on how to collimate binoculars. So let’s begin.

Key terminologies

How to Collimate Binoculars? Terminology and Step-by-Step Guide!
Main parts of binoculars.

Before we dive straight into the six steps, there are some key terminologies and parts of binoculars you should know. With this knowledge, you will not fiddle with the wrong places when repairing your equipment. These include:

  • Barrel – The main body of the binoculars, which houses most of its optical elements. It also contains the eyepiece lens system.
  • Eyepieces – Eyepieces are small lenses at either end of the barrel. They allow light from an object to enter the eyepiece. The first lens located near your eyes is known as ocular. The lens that is further from your eyes is the field lens. You should note that there are various types of binoculars. Each has a different number of eyepieces. Some have two, others three or more.
  • Hinge – A hinge connects the two parts of your binoculars. It makes it easy to adjust them up and down so they can suit your eyes.
  • Barrel Bridge – An area between the barrels of your equipment. It holds essential parts such as the focusing knob and hinges.
  • Objective lens – You can find this lens at one end of the barrel. Its job is to gather incoming light rays and direct them towards the eyepiece. It is sometimes known as a collecting lens due to its function.
  • Focusing knob/wheel – Used to move the objective lens closer or farther away from the eyepiece depending on what distance you want to view things.
  • Porro Prism – Comprises of glass material used to bend light rays coming through the objective lens. The bending of light rays makes it possible to see images upright Trusted Source binoculars | Definition, Diagram, & Facts | Britannica Binoculars, optical instrument, usually handheld, for providing a magnified stereoscopic view of distant objects. It consists of two similar telescopes, one for each eye, mounted on a single frame. Binoculars are designed to give an upright view that is correctly oriented left-to-right. .
  • Roof prism – This is another type of prism used to ensure that only parallel light rays pass through the objective lens. Roof prisms are usually above the Porro Prism in many models.
  • Diopter adjuster – Adjusting diopter allows you to change the focus of your eyepieces. Each barrel has a diopter adjuster that helps you compensate for any differences between your eyes. For instance, your left eye might be worse than the right; you can use the left diopter adjuster to fine-tune the focus so that both eyes see an image of the same quality.

Tools and materials

There are some specific tools and materials you need to complete the task successfully. Here are the items you must get beforehand.

  • Hingle clamp or L bracket – The clamp will hold your binoculars in place during the collimation process.
  • Head torch – This tool is essential because it provides enough illumination as you work. If you don’t own one, you can use a desk lamp.
  • Anaglyph glasses – You can also use Bahtinov masks in place of Anaglyph glasses.
  • Screwdriver – Choose one which has s small flat head to fit into the collimation screws.
  • Sticky tapes – You will need sticky tape if you choose Bahtinov masks in place of Anaglyph glasses. The sellotape will secure the Bahtinovcovers onto your equipment.

If your optical equipment is still under warranty, you do not need any of the above tools. We recommend returning them to where you purchased them for repair or replacement. Please do not attempt to open them. Otherwise, you will forfeit the warranty.

Step-by-step guide

Follow this procedure at your own risk. Binoculars are delicate instruments and may break if mishandled. If the equipment is expensive, you should have a professional repair it. For cheaper models, the repair will cost you more than the price of replacing them.

You have several best binoculars under $200 that can meet your needs to choose from if you need a replacement. According to most user reviews, the cheapest and best-rated binoculars must be the Bushnell Legacy WP 10-22×50 Binoculars 121225. This particular optical equipment has incredible zooming capabilities, incredible power, and durability.

If you own a cheap model, you have nothing to lose by attempting to repair it. Here is the precise procedure you should follow to collimate your binoculars.

Locate the screw

Start by locating the collimating screws in the eyepiece side of your binoculars. Use a knife to lift the rubber or plastic coasting up since they usually are underneath your barrel’s rubber or plastic coat.

Do not confuse these screws with crosshead ones. You should only look for screws that will fit into a flat head screwdriver.

Mount the binoculars

Once you’ve found the screws, mount the binoculars onto the hinging arm using the hinge clamp or L bracket. Make sure that you mount them firmly.

Focus your binoculars on a stationary item. We recommend repairing at night so that you can focus on fixed stars or any other object such as a telecommunication antenna. The night sky will show that your equipment has poor collimation better than any object observed during the day.

How to Collimate Binoculars? Terminology and Step-by-Step Guide!
The object you choose must be stationary and not less than a half-mile away. If you are in the northern hemisphere, we recommend focusing on the Polaris star. On the southern hemisphere, observe the Sirius star.

Defocus one eye

Now, defocus one eye while looking through both eyes. Your left eye should see everything clearly, but your right eye should see some blurriness. It means that your right eye is out of alignment. This setting will fool your brain into thinking that it sees two different images.

You should note that this might cause eyestrain and headache. So, do not observe your object for an extended period. To defocus the right eye, use the diopter adjuster. Adjust it until you only see a blurry image on the right side. You can also achieve the same results by placing a colored glass on the right side of your binoculars.

Look through binoculars

Adjust the two barrels so that they can fit your inter-pupillary distance perfectly. Use your diopter and focus wheel on adjusting the image until it is sharp.

If you notice that the sharp image on the left side is off-center from the blurry blob on the right side, it means your binoculars are out of collimation. If not, your binoculars are okay, and you do not need to collimate them.

Adjust the screws

Adjusting the screws is the essential step in the whole procedure. As such, you need to be extra careful not to damage your equipment.

While in the eye relief position, use a flat-headed screwdriver to turn the collimating screws. It would be best if you only made tiny adjustments on each side while you observed the images. We recommend turning the collimation screws about an eighth of a circle each time.

Adjust the screws till the sharp and blurry blob images are in line. Now, adjust the right side so that both images are sharp.

Fix the coating

Viola! You have successfully collimated your binoculars. You should now put the rubber or plastic coasting you removed back into its original place. You can glue it so that it fits perfectly.

Final thoughts

The binocular collimation process is that simple. Keep in mind that you have not fully collimated your equipment. You only did conditional collimation for the inter-pupillary distance you used during the procedure. Images will only appear sharp when you focus on them using that specific distance. When you use a different inter-pupillary space, you will notice that the equipment is still out of collimation.

Hence, this procedure on how to collimate binoculars is just a temporary fix. You will be better off purchasing a piece of new equipment for better viewing at any inter-pupillary distance. Your replacement should be rigid and able to handle extreme conditions so that it doesn’t go out of collimation quickly.

According to most user reviews, the Nikon 12×50 Action Extreme Binoculars 7246 must be the most affordable and powerful gadget you can purchase to replace your faulty binoculars. Thanks to its rigid construction, this model offers a reliable performance even under extreme conditions.


binoculars | Definition, Diagram, & Facts | Britannica
Binoculars, optical instrument, usually handheld, for providing a magnified stereoscopic view of distant objects. It consists of two similar telescopes, one for each eye, mounted on a single frame. Binoculars are designed to give an upright view that is correctly oriented left-to-right.
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