-
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.
Glasses and Diopter Adjustment (1 Viewer)
- Thread starter nodd
- Start date
Hi Neil,
Why are simple explanations the most difficult?
The answer to your question is yes.
If your glasses give you 20/20 Vision you have to make the diopter adjustment that will give you equal vision in both eyes. That follows through if the vision in your eyes is not equal. You have to adjust the diopter to reflect that difference.
This assumes that there are no mechanical problems with your diopter which can happen.
New binoculars come with instructions on how to set the binocular's diopter.
Bob
Why are simple explanations the most difficult?
The answer to your question is yes.
If your glasses give you 20/20 Vision you have to make the diopter adjustment that will give you equal vision in both eyes. That follows through if the vision in your eyes is not equal. You have to adjust the diopter to reflect that difference.
This assumes that there are no mechanical problems with your diopter which can happen.
New binoculars come with instructions on how to set the binocular's diopter.
Bob
Last edited:
WJC
Well-known member
WITH OR WITHOUT GLASSES, binoculars must be focused for observing objects at various distances. Some people think because there is only ONE diopter ring on a center-focus binocular that you set it and forget it. Although the diopter adjustment on the other side is done with the focus nob or a flip lever, it’s still a diopter adjustment. In order to really focus, it must be. The AUTO-FOCUS fraud of a few years back was just that ... a highly successful advertising scam aimed at the unwary!
The diopter RING is for setting the dioptric difference between your eyes—in only 2-3% of the population is it the same. The focus wheel or flip lever adjusts the focus on BOTH SIDES. You focus the side with the wheel or lever and then set your diopter. Many people—including me—ignore those numerals and even set THAT side to where it is most precise and comfortable.
About apologizing: DON’T! There is not a question on a binocular forum that has not be asked and answered about a bazillion times. :cat:
Cheers,
Bill
The apology was just incase as I know on some forums some people get touchy about re asked questions.
I am aware that binoculars have to be focused for different distances. It was I was wondering if your eye sight has been corrected by your glasses do you still need to set the diopter for each eye? This may be the wrong term to use in that you still need to calibrate the binoculars for the person using them?
There are several reasons why a spectacle wearer should adjust the dioptre to reflect differences between the eyes and here are some of them.
The dioptre markings on binos are not meant to be used as if they are on an opticians instrument, they are there to help you note your personal setting and return to it if the setting gets moved. So the bino is not necessarily set perfectly to Zero when the dioptre adjuster says so although bino manufacturers do try to achieve this.
Also your spectacle lenses are made to tolerances like all other manufactured products so they will be very close to what the optician ordered but not necessarily perfect.
And don't forget the prescription for your lenses was based on your answers to the opticians questions asking you 'which is sharpest? This one or this other one? and if you are like me you will have found those questions not so easy to answer as the optician approached the final choices. So your own answers on which your spectacle lenses were based my not have been perfect either.
Doing the dioptre adjustement check is the best way to ensure you are getting the best performance from your binos and remember, whatever dioptre setting you arrive at, whether it is Zero or plus something or minus something, you cannot guarantee this same setting will be as suitable for you on a different pair of binos.
Good luck.
Lee
The dioptre markings on binos are not meant to be used as if they are on an opticians instrument, they are there to help you note your personal setting and return to it if the setting gets moved. So the bino is not necessarily set perfectly to Zero when the dioptre adjuster says so although bino manufacturers do try to achieve this.
Also your spectacle lenses are made to tolerances like all other manufactured products so they will be very close to what the optician ordered but not necessarily perfect.
And don't forget the prescription for your lenses was based on your answers to the opticians questions asking you 'which is sharpest? This one or this other one? and if you are like me you will have found those questions not so easy to answer as the optician approached the final choices. So your own answers on which your spectacle lenses were based my not have been perfect either.
Doing the dioptre adjustement check is the best way to ensure you are getting the best performance from your binos and remember, whatever dioptre setting you arrive at, whether it is Zero or plus something or minus something, you cannot guarantee this same setting will be as suitable for you on a different pair of binos.
Good luck.
Lee
Last edited:
Hi Lee
Thank you your answer has helped a lot. I just want to make sure I am getting the best from my new Swarovski 8.5 x42 EL
Cheers
Neil
I wear glasses and have the same bins and adjust the diopter quite often as my eyes can shift a little at different times of day or if I've been on the computer a lot etc. Also experiment with the inter-pupil distance (ipd). For me it ergonomically feels comfy and natural to set it quite wide, but I find I get a better view (snappier focus, more immerse and 3D) if I set the ipd narrower.
Hi thank you I’ll give that a try.
WJC
Well-known member
The following is from a piece I did for The Nov. 2019 Southern Boating. It may very well answer questions related to nodd’s, “I just want to make sure I am getting the best from my new Swarovski 8.5 x42 EL” and mpeace’s, “... and adjust the diopter quite often.” While learning to stare is critical to maintaining a good view at any distance, optical engineers very rarely consider its importance, observers never know to consider it, and too many feel what they don’t know won’t hurt them. They’re right ... but it can make for a frustrating outing with the birds.
“... FINALLY, THE IMPORTANCE OF LEARNING TO STARE
“Your mother probably taught you it’s not nice to stare. However, for the most pleasing observing experience you had better forget that advice.
“There are two phases to focusing a binocular. The first concerns the focus mechanism—the actuation of the focus knob, diopter ring, or flip lever. That’s the one seen almost exclusively by the observer.
“The second is through the involuntary focusing of the eye through the eyelens being stretched or compressed by the eye’s ciliary muscles. Our brains want to see things in focus quickly and will use those muscles to the detriment of the viewing experience.
“Let’s suppose you want to see a target at a certain distance and start turning the focus knob to achieve the best image. The target may become sharply focused for you at -4 diopters, although your “at rest” diopter setting should be -1 (arbitrary numerals selected). Yes, the image is focused, but only so at a strained setting. Then, when you start adjusting the binocular’s focus mechanism—without considering the importance of staring—you will repeat the mistake and the problem remains.
“Learning to stare can prevent the eye’s involuntary input and limits focusing to that achieved through the binocular’s focus mechanism. This leaves the observer in control of whole focusing operation as opposed to having the two aspects of focusing fight each other while you try to attain and accurate focus for an object at a given distance." :cat:
Last edited:
Chosun Juan
Given to Fly
An interesting question and everybody has contributed some useful and though provoking answers.
I wear glasses (tested within the last couple of years). I would have said a hard no - why complicate the optical system with further variables? (I seem to have some recently accquired astigmatism in one eye which doesn't provide the elegant solution I would like).
Already with my consumer level bins I am dealing with marginal eye relief, the vagaries of the precision of the exit pupil (tolerances and spherical aberrations and what not) and the limitations imposed by lack of ER degrees of freedom, far from luxurious randpupille (margin of error for alignment contained by the optical design - Swaro's are some of the best in the business !), alignment of the bins with that, and the particular curvature and spacing of my glasses (short-sighted) , and some slight mechanical focusing hysteresis, and focus wheel backlash to boot.
This used to absolutely annoy the heck out of me ! Now however, various injuries put this optical and mechanical imprecision in stark relief, and from this new perspective I'm just glad that I can see stuff better than with my similarly dodgy mark one eyeball !
Also, I realize that my eyes too have much variation in them depending on conditions and how tired etc my eyes are. I've seen everything from various apparitions, the trees shimmying and shaking as they talk to me, I've had Eagles talk to me (they want people to stop photographing around their nests !) , and at certain times of the afternoon my eyes take on individual colour casts (one orangy-goldish, the other blue green - David Bowie-like, which I like to kid myself makes me some sort of genetically superior super predator - lol 3
)There are times when I get a really clear view (especially when the objective and ocular lenses are clean !) , and yet there are other times when nothing I seem to do helps get a clear view. I will give the Staring technique a go (but that could quite easily take me further out of this world !) - if only I could get those danged geewhizzits to sit still long enough ! :-O :cat:
I'm going to leave my diopter at zero (otherwise it's a trip back to the optometrist for a refund !) , but by all means, if it helps, play around with it a bit.
Chosun :gh:
WJC
Well-known member
I'm going to leave my diopter at zero (otherwise it's a trip back to the optometrist for a refund !) , but by all means, if it helps, play around with it a bit.
Chosun :gh:
Hi, Chosen,
If you leave your diopter adjustment at “0,” as you say, like so many others—and the optometrist has tested you at something else—your observations will be out of focus by that amount.
Please keep in mind that while learning to stare is easy for some people, it is very difficult for the majority. And, of course there are those who claim it doesn’t matter—reference my signature statement.
A test:
Focus your bino clearly on a target at least a mile away. Then, defocus until the image slightly annoying. Now, remove it from your eyes with NO further adjustment. Return to looking at your target with your unaided eyes. When your focus is sharp, quickly return your binocular to your eyes. If your image is still annoying for several seconds, you have learned to stare. If the image is pretty good, you have not. That means your ciliary muscles have involuntarily taken over. And as Aristotle was prone to say: “Bad juju.” :cat:
Bill
Chosun Juan
Given to Fly
Thanks Bill :t:
I did try various diopter settings at the start - but settled back on "0" (who knows - perhaps my optometrist fluked it - these were the previous script before the wretched astigmatism started to creep into one eye ..... still in denial about that one - lol :-O )
I have noted a change in my dominant eye from right to left now - my bowling (lawn) seems to have adapted (even if it confuses me .... I've agreed with myself to not think about it, and just try and get something close !
I will give the Staring thing a try sometime :t:
(my birding buddy has locked himself away until the spring)
Chosun :gh: