There are rumours around the internet and people are concerned that binoculars are bad for your eyes or can affect your eyesight. Before writing this article, we’ve done some in-depth researches and asked a few professionals if the binoculars are bad for your eyes.
Are binoculars bad for your eyes? It depends, in general binoculars can do no damage to your eyesight if they are used correctly, however, this is not always the case, where for short term you may experience fatigues if the binoculars are used incorrectly, in the long-term run, this can affect your eyesight.
Binoculars are working under the same principle as having eyeglasses but in a more complex matter: if you wear the wrong glasses for a long period of time, this can damage your eyes.
Furthermore, in this topic, I want to largely talk about when and why binoculars may affect your eyesight, how to improve your watching through binoculars without hurting your eyes and some other information we were able to cumulate during our researches.
Can binoculars affect your eyesight if used incorrectly?
If you are wearing glasses, you may know what I am talking about. Have you ever been worn a wrong pair of glasses? Did you notice that if the glasses have the wrong dioptry and are not the ones prescribed by the doctors, sometimes you feel like having a headache, fatigue and your experience is relatively negative?
The same principle goes with the binoculars. But with the binoculars, there can be more issues than the diopter level, such as collimation, bad glass quality and even the simple fact that your brain may not easily accept that you see many times closer than you should be, and this for a longer period of time, may have a negative effect. But this does not mean it can affect your eyesight.
Adjusting the right diopter level
If you have noticed, every binocular have a diopter adjustment as in the picture above. This can be either one of the eyecups or both which allows for you to adjust the diopter level.
Even if you are not wearing glasses like myself, there is a probability that your eyesight can be slightly impaired and there is a small diopter difference when watching through binoculars, therefore, never use your binoculars with the diopter level set to 0 unless you adjusted for your eyes and you are sure that this is rightly calibrated.
How can you adjust the right diopter level?
For the binoculars with two diopters and focus adjustment, the easiest way is to do it eye by eye. There is no additional focus ring as in the 25×100 from Celestron, therefore, when you watching through binoculars, focus your either left or the right eye while the other one is closed or a cup covers the objective, then do it vice-versa.
The most standard binoculars will have only one eyecup adjustable for the dioptry and a focus ring. The easiest way to do this is as following:
- Select an object you want to focus on through the binoculars (neither distant nor close to you)
- Close your right eye or put a cup in front of the right objective, so you can see only through your left eye. Now use the FOCUS RING to perfectly focus on that object.
- Further, cover the left objective or close your left eye. Now use the dioptry adjustment ring to perfectly focus on the same object. Do not touch the focus ring.
- When the right eye is also focused as the left one, this means your diopter level is adjusted per both of your eyes. From now on, use only the focus ring to focus when watching through the binoculars.
- If this goes out of focus by accidentally touching the diopter adjustment ring, repeat the process again.
By following this process, you adjust your binoculars to your eyes, therefore, this will decrease or eliminate the negative effects of watching through binoculars and may not have at all a negative impact to your eyesight.
How to focus right with the binoculars?
Reflecting on the above points, let’s assume that the binoculars are adjusted to your eyes and from now on, all you have to do is to focus on the subject/scene you want to observe.
There is no simpler way to do it than to use (ONLY) the focus ring or as per some binoculars models, focus per each eye. But now, what is the right level of focus?
I call it a level, as when you focus the binoculars before to get your subject or scene in the right focus, this is out of focus either closer or farther than your subject or scene. Now you focused on your subject, but you may notice sometimes that you still have to use your eyes muscles and work your brain to (again mentioning the word) focus on the subject.
To relieve the eye muscles, keep your eyes relaxed to maximum when watching through the binoculars and adjust your focus ring until you see perfectly clear through the binoculars without to stress any additional eye muscles.
By doing this, you decrease your level of fatigue, headaches or any other negative effects when watching through the binoculars.
The collimation of the binoculars
When you are watching through the binoculars and see double, this means that the binoculars MAY NOT BE properly collimated. Your brain forces your eyes to merge the images seen throughout the binoculars into a single image.
This can simply happen also if you did not adjust properly the binoculars distance between your eyes, but if this is not working, that means that the binoculars are not properly collimated.
Sending the binoculars to a specialized shop could be the easiest thing you can do in special if you are not a DIY person, but this can be also repaired and recollimated at home. Please keep in mind that this will not work with all the binoculars.
If you want to read more please check this external article from cloudynights about how to collimate your binoculars.
To underline the importance of this, uncollimated binoculars can cause headache, fatigue, problems focusing and force your brain and eyes unnecessarily to repair the double vision. This can also have a negative impact to your eyesight if often used for a long period of time.
Using binoculars with or without glasses?
Most of the binoculars manufacturers are producing the binoculars to be glasses friendly, for the eyecup to have an adjustable heigh and for the binoculars to be used by both glasses wearers and without glasses.
But did you know that you can actually use the binoculars without glasses? Remember, the adjustable diopter level can work a couple of diopters plus/minus, depending on the binoculars model.
If you want you can read more on our other article “do you need to wear glasses with binoculars?“
In general, both of the options to watch through binoculars with glasses or without glasses can have no impact on eyesight, if this is done properly. It’s more like a matter of personal choice.
How bad it is? Do your eyes are getting tired after using the binoculars?
If your eyes are still getting tired after using the binoculars, most probably is because of one of the above reasons. Rarely can be something different but not excluded.
Please be aware and careful if your eyes are getting tired after using the binoculars, you have problems focusing, feeling fatigued or having a headache and there is nothing you can do to fix this, make sure that you are using them only for very short periods of time to reduce or eliminate the above-mentioned risks. If you are feeling much worse after a session with the binoculars, I recommend you to stop using them until you identify the problem and work for a solution.
Moreover, to keep in mind, I (we) are not to be held responsible if the above tips are not working and/or your eyesight is worsening. Please speak with a professional optician for advice related to your eyes vision.
How do I know if I am using right the binoculars
Whenever you are having sessions with your binoculars and even for longer periods of time and present none of the above negative effects, you are probably using right the binoculars.
It is difficult to say as even the slightest diopter change can have an impact on the long-term and often usage of the binoculars, where during a session you may not notice any difference.
But using the binoculars may come with a risk for your eyesight, same as watching TV, electronic devices, checking your phone and playing all day long etc. Those can be worse factors which can affect your eyesight than the binoculars.
Are binoculars bad for your eyes? Some extra information to avoid affecting your eyesight.
Have you ever heard of exit pupils? An exit pupil is the diameter of the light beam going out through the eyepiece directly to your eyes pupils. A human’s eye pupil is open about 2-3mm during daytime and up to 7mm during the night for the eyes to capture more light in darker environments.
The exit pupils of the binoculars are calculated by dividing the objective lens diameter to the magnification (e.g. 10×50 binoculars: 50/10=5mm exit pupils). If the exit pupils of the binoculars are too small, not enough light may enter your eyes pupils. As an example, if the exit pupils or light beam diameter is of 1.5mm and your eyes pupils are open about 5mm in given lighting conditions, all the light is focused to a 1.5mm area out of 5mm from your pupils.
In this case, you will see a lot darker the image than you should and your brain will force your eye muscles to spot and to focus on details. This can have a negative impact on your eyesight and eyes in general.
There can be a lot more factors which can impact your vision in time when watching through binoculars and you have to be responsible for the usage of the binoculars. Beware, that binoculars, scopes and telescopes are powerful optical instruments.
Watching through binoculars directly towards the sun can instantly damage your eyes. NEVER DO THAT without any special solar filters.
Thank you for reading our article and if you have any questions please do not hesitate to leave a comment in the section below. I am not an optician but I have experience with the binoculars and for this article, I did in-depth research and asked a few professionals to help out with any tips we shared above.