Why Do I See Double When I Look Through Binoculars?
Binoculars are two telescopes that are affixed to each other in a side by side position. When properly orientated, they can be used to view an erect image of an object in the distance with both eyes. Binoculars incorporate 2 lenses. The first is known as the objective lens which picks up the rays from the object and produces a focussed image. The second lens then takes this image and magnifies it.
If you can see double when you look through your binoculars, there is likely an issue with the collimation. You may find that the path of light becomes distorted and as a result, the quality of the image is altered and this will create a different image between each side of the lens.
The term ‘collimation’ refers to two images that merge within a tight tolerance. Binoculars that are not correctly centered are going to require adjusting to fix and improve the quality of the image.
You may see double when looking through your binoculars because of a personal issue that affects your vision. For example, if you have one eye that is more dominant than the other, you are likely to have better vision in this eye in comparison to your other eye.
As such, when trying to focus your vision on the view through the binoculars you may find that you cannot focus on a target, and instead, the view appears to be doubled or a little blurred.
Rectifying the collimation of your binoculars can be quite a complex task and because of this, you may prefer to take them to a professional who will have more knowledge in fixing this problem.
How to fix double vision in your binoculars
Now that we have identified potential reasons as to why you are seeing double when looking through your binoculars, you may be wondering what steps you should take to fix the problem yourself.
It is worth noting that several manufacturers will cover their binoculars with a warranty for collimation adjustments. If you try to fix the collimation yourself, this warranty will be void. As such, it is important to thoroughly read the documentation that you have been provided with when you purchased the binoculars to check these details.
Below, we have identified several steps that you will need to follow to fix the collimation of your binoculars. You are likely to witness a noticeable improvement in the quality of the image after doing so.
Assemble your tools
First, you must make sure that you have all of the tools that you need available. With the right tools on hand, the task will consume much less of your time. To remove the small components and screws, you will need a small screwdriver. A tripod and adapter will also prove helpful as you will be able to position the binoculars as you work on them.
Find the adjustment screws
Next, you will need to locate the adjustment screws on your binoculars. The user manual provided will typically detail the exact location of these screws. If you cannot find this information in the user manual, a quick browse online will likely tell you where the screws are on your exact model. Normally, they are covered by plastic or glue to protect them from tough handling, however, this can also make them more difficult to find.
Attempting to adjust the collimation of your binoculars can affect the calibration, hence why most manufacturers recommend that you take them to a professional instead of trying to do it yourself.
Remove the necessary components
The next steps involve removing the necessary parts of your binoculars. If there is a plastic housing surrounding the adjustment screws you will need to remove this using a screwdriver. There may also be an adhesive coating near the eyepieces which will need to be pulled off.
Adjust the screws
Now you will need to adjust the horizontal and vertical screws. Starting with the horizontal screws is advised. Complete 1/8th of a turn at a time, alternating between each side at a time. If you do not adjust both screws at the same time, you will not notice any improvements in the quality of the image and because of this, it is important to adjust each side in equal measure.
Following this, you will then need to adjust the vertical screws. Again, you will need to establish 1/8th of a turn each time, taking a break after each rotation. Remember to do this equally on each side of the binoculars.
Refocs the lenses and test the collimation
Once you have adjusted both sets of screws, you will need to refocus the lenses and test the collimation. This is where the tripod will come in handy. Position your binoculars steadily on the tripod. Now you will need to refocus the lenses that you unfocused to make the adjustments.
To ensure that your binoculars are accurately calibrated, you may wish to use them to view objects in the clear sky. If the object that you have focussed the lenses on is still off, this is a sign that the collimation isn’t quite right.
Another test that you can carry out to check the collimation involves closing your eyes for a couple of seconds and then focusing on a specific object once you reopen them. If the object appears to be a single image, the collimation of your binoculars is sufficient and you are good to go. If you can still see doubles, you will need to make further adjustments.
As you can see there are few reasons as to why you may be seeing double when looking through your binoculars. It is most likely due to the collimation, which can be quite tricky to fix and can hinder the overall quality of the image. If you do not have experience in fixing this issue, you may prefer to take them to a professional who has experience in tackling such problems.