-
Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.
Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
What causes eyestrain when using a binocular? (1 Viewer)
- Thread starter Ted Y.
- Start date
As far as I understand, binoculars are tiny telescopes aligned together (forgive any lack of technical correction, not sure if alignment and collimation are exact synonyms), and in order to give a satisfactory experience, the two tubes must be aligned to a quite small tolerance. So:
Anyway, be it a serious miscollimation (where you see double) or a lesser lack of alignment (varying from a "jump to norma" to varying levels of eyestrain or headache, a properly aligned and a properly adjusted binoculars should cause no eyestrain whatsoever, so if your unit does, it's a living evidence that it's not quite right, even is the barrels seem identical (we are talking about minute differences that are not detectable from the outside).
I'm sure more knowledgeable forum members will inform you in further detail, but basically: if you set up your binoculars properly (dioptre adjustment, cups up/down, correct interpupillary distance, proper eye positioning, etc.) the view should be easy and free of any strain, regardless of the configuration you choose, be it 6x30, 8x32, 10x42, etc.
It is true that some users prefer some formats for a series of reasons. For example, I like 7x35 or 7x42 because I find them "easy on the eye", the view is relaxed, there is a stable view with plenty of depth of field, but this is just a "personal sensory" preference. I've used 6x, 7x, 8x, 10x, 12x binoculars and, when properly adjusted, none has caused any strain, although I tend to find binoculars with smaller exit pupil and bigger magnification a less easy to use, while big exit pupil and lower magnification feels effortless and pleasurable to my eyes.
- if the difference is quite big, you will simply see two different images, and your brain won't be able to fix it or merge them in one single image (what any properly adjusted binocular does), this is why sometimes many viewers claim to "see double", like if they were drunk; a double image is a clear sign of a severe lack of alignment.
- however, even if everything looks OK from the outside, the two tubes can still be poorly aligned, in some cases not enough to cause double vision, but indeed to "force" your brain in order to merge those images into one. So, you can use the binoculars, you get an apparently "correct image" (a single focused subject), but when you put the binoculars down you feel discomfort, as in eyestrain or headache, sometimes in the frown, between your eyes. Again, this can vary from a sudden and noticeable pain between your eyes the moment you put the binoculars down (when you suddenly feel your eyesight coming back to normal) to a lesser headache of varying intensity, which sometimes only manifests itself after a more pronounced use.
Anyway, be it a serious miscollimation (where you see double) or a lesser lack of alignment (varying from a "jump to norma" to varying levels of eyestrain or headache, a properly aligned and a properly adjusted binoculars should cause no eyestrain whatsoever, so if your unit does, it's a living evidence that it's not quite right, even is the barrels seem identical (we are talking about minute differences that are not detectable from the outside).
I'm sure more knowledgeable forum members will inform you in further detail, but basically: if you set up your binoculars properly (dioptre adjustment, cups up/down, correct interpupillary distance, proper eye positioning, etc.) the view should be easy and free of any strain, regardless of the configuration you choose, be it 6x30, 8x32, 10x42, etc.
It is true that some users prefer some formats for a series of reasons. For example, I like 7x35 or 7x42 because I find them "easy on the eye", the view is relaxed, there is a stable view with plenty of depth of field, but this is just a "personal sensory" preference. I've used 6x, 7x, 8x, 10x, 12x binoculars and, when properly adjusted, none has caused any strain, although I tend to find binoculars with smaller exit pupil and bigger magnification a less easy to use, while big exit pupil and lower magnification feels effortless and pleasurable to my eyes.
I asked for a collimation check under warranty.
WJC
Well-known member
There are two major culprets: Spatial Accommodation and Dioptric Accommodation. The attached describes Spatial Accommodation. If you want information on Dioptric Accommodation, I will send you that, too. You seem to be seeking more in-depth information. You won't find it on bino forums. Use Wikipedia to FIND a COMPETANT source and then go directly there. Too many times people want instant solutions (opinions) to complex problems (facts) without being willing to take the time to learn. That is not in the realm of many optical realities.
Attachments
Last edited:
WJC
Well-known member
I will do so tomorrow at the earliest. 'Tied up in the morning. MY opinion is based on the science.
WJC
Well-known member
Hi, Ted, On another thread you seem to indicate only two posts needing attention. As you gain knowledge of optics and binoculars, you will see that the FOUR I mentioned are all related. I did not find the original text I wanted. Categorized as best I could, my computer still has tens of thousands of documents on it. The attached is an article I did for Times of the Islands. I will continue to look for the original article if this doesn't answer your questions. The last two pages are the most important for your needs.
PS All of these photos are right side up on my computer. However, computer geeks rule the world. Let me know if you can read it.
Attachments
Last edited:
WJC
Well-known member
Most of us are. Navy Opticalman training did away with that for me.I can read it, I rotated the monitor 90°
Thank you
I will take some time to try and observe how this is happening.
Just as a mention, I am culturally conditioned 'not to stare'.
WJC
Well-known member
Nope. My friend, the eyestrain you keep worrying about is all self-inflicted. People who look for problems will always find them. If you deal with the 2 major contributions I told you about, others anomalies would be taken to the "not to worry" category. I realize there is enough to worry about on bino forums to keep you worried, forever. However, most of those worries come from optically clueless people! People who build their lives around hearsay and flawed opinions! Break away from that crowd.
Last edited:
Rotherbirder
Well-known member
An excellent, common sense/no nonsense article which can be easily proven to be true just by following it with a binocular to hand. All subscribers to the forum should read and acquaint themselves with it post haste! What was that saying about organ grinders and monkeys again? If you want to know the truth, speak to the former and not the latter!
RB
