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How To Adjust Binoculars With Double Vision

Sometimes, you can drop, hit or sit on a binocular on purpose or by mistake.

Whichever way, chances are the optics of your binocular will misalign. Shipping and delivery can also cause loss of collimation.

With binoculars focus problem come annoying double images.

More expensive binoculars are less likely to lose collimation.

Collimating inexpensive binocular isn’t worth it if you’ve to pay for a price that’s more than buying a new one.

Luckily, you can learn how to fix binoculars double vision problem at home.

But you can do that partially.

You’ve two options:

  • Adjusting tilt screws to align prisms
  • Disassembling the optics


  • A set of a small, flathead screwdriver to adjust the tilt screws and break a locking glue or adhesive.
  • Your binocular whether it has a porro or roof prism
  • A tripod and a tripod adapter
  • A hinge or L-bracket clamp to hold the binocular firmly.
  • A head-torch to light up the task hands-freely.
  • A hobby knife or a penknife to remove adhesives or glues covering the tilt screws.
  • A laser beam generator.
  • A ruler
  • A tape


  • A printout of Bahtinov masks on a transparent film. Ensure spaces around one mask between the three tabs are even, so you can tie them down on to the binocular.
  • Tapes with stickers or elastic bands to attach the Bahtinov mask to the binocular.
  • As an alternative to Bahtinov mask, use filters of different colors such as cellophanes or three-dimensional anaglyph glasses, especially during daytime.

Important Steps for How to Adjust Binoculars with Double Vision

If you know how to adjust or fix your binocular that has double vision problem so you can save a lot of money. Here made the fixing process very for you. Read every step carefully and apply it to your binocular. Read on to learn more.

How do I Know if Collimation Loss is Present?

First off, look out for any external damage, like bending of the tubes. 

If external damage is absent, go outdoors and test your binocular under a day or night sky.

Ensure the interpupillary distance between your eyes matches the binocular.

To prevent your brain from merging divergent images, you can trick it that the images are not identical in three different ways:

  • At nighttime, under a sky, select the brightest star and defocus either a right- or left-hand ocular lens. If optical misalignment is present, the image of the star which you focused on from one side should move away from the center of the image of the same defocused star on the other side.
  • Create color contrast between images of the same star from either side using filters with different colors. Three-dimensional anaglyph glasses or cellophanes with different colors can work. Colored filters are suitable for daytime testing when merging images of objects like roof edges or power lines.
  • Arrange Bahtinov masks such that the angle between each is 90º. You’d need to generate or print out each mask.

How do I Locate the Tilt Screws?

Manufacturers usually hide the prism tilt screws under a layer of adhesive, latex, glue or rubber for two main reasons:

  • To protect them from weather elements
  • To prevent you from adjusting them intentionally or unintentionally

But in this case, you’ve no choice other than to adjust them intentionally.

Often, there are two or three pairs of prism tilt screws, and they serve two purposes:

  • Horizontal adjustment
  • Vertical adjustment

Tilt screws closer to the objective lenses than the eyepieces are for vertical adjustment. Horizontal adjustment screws are nearer the eyepieces.

We recommend you adjust only the tilt screws for horizontal adjustment, because they are usually misaligned.

Be careful when slicing open the layer to prevent cutting yourself, touching the screws accidentally or spoiling the covering. Focus on slicing the area where the screw is.

Repeat the procedure for the other horizontal adjustment screw.

Ensure you select the right size of a flathead screwdriver from the set.

Mount Your Binocular onto a Tripod and Select a Target

Once you mount your binocular onto a tripod, you can pick a target of your choice. Ensure your binocular is level and vertical with the tripod. Bubble levelers can come handy.

But if they’re lacking, you can create a plumb bob of some sort. You can hang from a rope a heavy object to check whether the tripod’s neck is vertical.

As for leveling the binoculars, find a tube into which you insert a marble whose diameter is slightly less than tube’s bore.

Line up the head of the tripod with the center of the binoculars. Using a tape, attach a laser beam generator to either side of the tripod head.

The target should be stationary, or at least move slightly. Your target can be terrestrial or aquatic. For simplicity, terrestrial targets are suitable.

Make sure they are more than 3000-feet (1000-yards) away from you if your binocular has a magnification power of more than 8x. For lower powers, your targets should be inside of 500-feet (167-yards).

We recommend two types of targets:

  • Polaris
  • A rig cross

Alternatively, you can make a target by marking a cardboard piece with “+”. In other words, instead of drawing a cross in the middle of the cardboard, why not create four squares at the edges and shade them?

Your target should be level with the tripod. You can check for levelness using a surveying equipment. If you lack one, don’t worry. Improvise.

Go to your nearest lake, so you are pretty sure you’re level with your target. Hang your target from a tree near the lake. Make sure you’ve tied a vertical weight at the central part on the bottom of the cardboard.

Focus the laser beam at your target. Once it hits the target, focus the pan.

Afterwards, look through either eyepiece. If you did line up well, your eye should be near or exactly on target. One side should be left of the “+” target and the other away from. Select the side that’s nearest to the “+” and align it with the center.

The side that’s way off from the target should be adjusted horizontally if it falls outside the center to the right or left. But if the side falls above or below, then make vertical adjustments.

Make both adjustments if the side falls outside the center vertically and horizontally. However, make vertical or horizontal adjustment one at a time.

How to Adjust Binoculars Collimation Screws

Look through your binoculars with both eyes as you spin each screw crefully by less than 1/8 of a turn to study what effect on the image each turn produces. Keep track of every turn. Afterwards, rotate the screw back to where it was.

Now, rotate both screws at the same time till the both images are fully merged. Colored filters or Bahtinov masks can help you check whether the images are fully merged.

Test Your Binoculars

To check your binocular vision,  look through both eyepieces and move back your eyes slowly away. You’ll witness columns of light coming straight to your eyes.

If a light column is bent in either eyepiece, light isn’t getting into the center of the objective lens of the faulty side. That could be an indication of problem with the optics, which is beyond your scope.


Learning how to adjust binoculars with double vision at home can save you from having to buy a new one or seek a professional repair. Double images occur when both images of the same object from both sides of your binocular can’t merge.

Your brain will try to compensate for the divergence. If deviation from acceptable tolerance is small, you may not notice. But the more divergent the images are, the more headache, nausea or eye strain you’ll suffer.

Cheaper binoculars are more susceptible to the impacts of dropping or hitting. Professional repairs are usually more expensive than the costs of buying a new binocular. In a nut shell, you can’t completely collimate your binocular at home.

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