How to Collimate Binoculars

Learning How to Collimate Binoculars?

A binocular might not function as expected if all the elements are not in line. In such instances, you may end up having a product that is not working. The procedure of aligning the lenses is uniform for all the binocular brands.

Many people, however, are not aware of how to undertake this procedure. They would prefer to take it for repairs in the assumption that their tool is damaged. Such a process is costly in the long run, and hence the reason for this article. It carries all the information that you need to know about adjusting your binoculars. Please read on for more updates about how to collimate binoculars?

What is the meaning of collimating binoculars?

It is the process of aligning all the optical elements of a binocular along an optical axis. Initially, it was by adjusting the objective lens and the prism tilt screws. Once collimation occurs, you can see clearly through the binoculars, as there would be nothing to prevent the sighting!

When the binoculars are out of collimation, the images become blurry or dim. In some cases, it might even become impossible to see through it.

Why do I see double images through the binoculars?

It could be that the objective lens might be out of alignment. That means the optics are not well collimated, and hence letting in light irregularly. You should check the prisms as one of them could have fallen out of the alignment. Readjust the prims until you achieve a perfectly straight line.

Whenever you notice a double vision of the same object, the first place to consider rectifying is the prism. If that is not the case, then proceed to the objective lens. In some cases, it just needs some cleaning, and the vision restores to normalcy!

Disassembling the binoculars

Sometimes, it might not be possible to adjust the prism before dismantling the binocular. To disassemble, turn the external guard ring gently in an anticlockwise direction and take it off. But if it does not turn by hand using either a strap wrench or even an Allen wrench. The ring would come out freely if the counterclockwise motion is successful!

When putting it back, you should repeat the same process, but in a clockwise direction. Do not tighten it so much, such that it becomes problematic to open then next time you want to adjust.

What can make it not to focus?

The focusing ring could be out of the way and needs some adjustments. Look through the binocular with your left eye to find out of it is focusing or not. The ring should always be at the center of the binoculars, failure to which focusing might become impossible. The eye-ring brings the object that you are looking at into a sharp focus. On the other hand, the diopter on the right eyepiece justifies the difference between the left and the right eye.

How to clean binoculars?

If you do not clean your tool, it might not focus well, especially if the dirt is on the glasses. Brush off, or blow away the loose items on the lenses. Take a soft cloth or a brush. Do not use hard components as it might damage the binoculars.

Spray the lens cloth with a thinner or a cleaning solution and use it to wipe off the remaining dirt. Take great caution not to spray the binoculars directly. That is because it may corrode it or even erode the markings on its surface.

You can always use more than one cloth while cleaning it. One is for removing the tough stains and dust, and the second one can serve for rinsing!

How to adjust the diopter?

Look through the camera as you turn the little knob next to the viewfinder. Continue moving the knob until when the image gets sharp and clear. You can adjust it in either direction. If you do it to the left, then that is a negative adjustment, and when you do it to the right, that is a positive one.

Cleaning the interior of the binoculars

It does not get dirty often, but it is necessary to clean it quite often. If you let the dirt build-up, the binoculars might not focus in the long run. To clean the interior, get a specific cleaning solution and a clean, soft cloth that will not damage the lens. Take off the bottom plate and clean the inside of the objective lens.

Some binoculars have tiny screws. If you have one, then you must first remove them before opening the interior for cleaning. Remember to put back your tool it was before so that it can function as expected.

Can the diopter affect focus?

No, it does not affect. It only adjusts the clarity of the reflection that is from the prism and does not focus on the image itself.

The diopter balances the image quality between the left and the right eye hence producing an ultra-clear output.

How to choose a camera diopter?

A diopter plays a role when collimating your binoculars. It is, therefore, wise to choose the appropriate one for your product.

The procedure is to measure the distance in meters between the lens and the ground. It should be the point where you would get the best focus. Proceed and divide 1 meter by that distance. It will give you the value of the diopter of the lens. If, for example, your lens focuses the object at 2.5m, then the diopter value of the lens is +0.4 diopter lens. To obtain that value, you will divide one by the distance, as illustrated below:

1m / 2.5m equals to 0.4.

How a diopter works?

It is a unit of measurement for binoculars and other optical power devices. It helps in actualizing the collimation process of the binocular. It works on a curved mirror and hence equal to the reciprocal of the focal length of the lens. Its unit of measurement is in meters.

Frequently Asked Questions (FAQs).

How do you know if binoculars are out of collimation?

You would be able to determine by observing a bright star and then defocusing on the right-hand eyepiece. If there is any displacement of the object from the center, you would need to adjust the binoculars to correct it.

Why do I see double through my binoculars?

It happens when the objective lens drifts away from the center of the binocular. The prism also might have fallen out of the adjustment!

How to adjust binoculars with double vision?

The procedure is similar to the one above. However, you may require to get a wide field of view, similar to a football pitch. Look through it, focus on the objects and fix appropriately the binoculars.


Collimation is a necessary process in binoculars. As you put it to constant use, the prisms tend to fall off the location. Focusing is, therefore, impaired, and you will need to make some adjustments to rectify the error!

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