I wasn't aware of the fact that some binos don't have diopter adjustments.

Some of the cheap ones don't, but most do. Few people really know how to use them though and I always find myself adjusting from the previous looker.

I am amazed at what some find acceptable as a difference from one eye to the other in dioptric power (anisometropia) as I can not tolerate much, but I know what I am looking at since I am in the field of eyes.

I also think a lot of people suppress one eye when its too blurry and don't even know it is happening.

You're assuming an awful lot. Not sure why you think you wouldn't have to adjust the diopter if you're borrowing someone else's bino? What specific binos don't have diopter adjustments? I guided hunts for 16 years, over 150 hunters. I never saw one that didn't so educate me/us.

He may be assuming a lot but I amazed that probably 90% of people who own scopes don’t know it has a diopter adjustment. Much less how to use it or what it means.



Edit: because I said some stupid [censored].

If adjusted properly, the diopter adjustment should not have to be changed from one person to another if they person is wearing visual correction, meaning glasses or contacts. for people who do not wear any kind of correction, there should be no adjustment going from one person to another.

What I am saying is people use the focus on binos (and probably scope parallax thinking it is a focus knob and not a parallax correction) to focus their correction if the diopter power is off. I have seen it a lot. The focus knob on binos is not designed to be maxed out for dioptric power but for near-er and more distant object being looked at. By using the focus knob on binos to focus dioptirc power, you are not fully able to utilize the binos ability to focus at all ranges.

I don't have any specific brands or types of binos I have seen that don't have diiopter power correction, but they were, as I said, very cheap. and I have seen some with rotating eyepieces/oculars that didn't change a thing. So just having a rotating ocular does not necessarily mean a focusing diopter power.

Sorry if I offended you or made it sound funny. I was not trying to assume anything at all.

I'm not offended at all, so no problem there. This is where I'm struggling to agree with you. I've never used another hunter's, or friend's bino without having to adjust the diopter for my own vision.

JGraiider I’m with you on this. If his argument held true there would be two settings on the diopter. Corrected vision and non corrected vision. His statement might be true scientifically, but it’s not in practice to my experience.

It’s hard for me to disagree with a guy in his own field. We need more information Buckeye.

Just to be clear, we are talking about the diopter power adjustment on the ocular of binos and eyepiece of scopes. If properly adjusted, the diopter power should not have to be changed going from a person wearing glasses or someone who doesnt wear glasses and two people who dont wear any correction at all should be able to use the same pair of binos without having to change anything.

This is not the same thing as eye relief adjustment, that is very different from changing the diopter power of the ocular..

I guess maybe the fact you guys have had to adjust so many binos is making my point for me. But i should be able to hand you my binos and you should he able to use them without having to adjust anything other than eye relief and pupillary distance to your personal preference. It is the same concept as me sitting behind a microscope that is properly adjusted for zero prescription and it should not need adjustment for my eyes other than pupillary distance.

Help me understand where i am failing to explain this better.

The diopter power correction is a variable adjustment to account for multiple powers. Most have a limit, somewhere around +4 to -4 diopters or somewhere around there (i looked up the swaro nl pure range)

Meaning if you are a -6 glasses wearer and take off your glasses to use binos, you are using some of the focus knob to correct the remaining diopters of power needed and are not able to fully utilize the binos to their greatest range. And that’s if you have the diopter power max’d out. If you dont, you are losing quite a bit of range by using the focus knob for 6diopters of power right off the bat.

The fun comes when one ocular is set for -2 and the other is set for +2, that will drive me batty, but its amazing how many people just dont seem to notice it.

Sorry buckeye, we're either talking about two different things or you have no idea what you're talking about in the real world, in the field use of binoculars. I'm not referring to riflescopes in my posts. I've never heard the diopter adjustment as being a "diopter power" correction.

One last try to post what my brain is thinking......with the objective eyecovers on the binocular, cover up the right eyepiece with one and use the focus wheel to get your left eye a sharp, clear view. Then put the cover over your left eye, uncover the right eye, and use the diopter adjustment to sharply focus the right eye. I usually focus on tree bark or some other highly detailed target about 30 yards away. After these two steps, uncover both and from there on use the focus mechanism on the bino. If you did this correctly both eyes will be in sharp focus at the same time. I guarantee you this will not be a universal, one fits all, adjustment amongst various users.

FWIW, on riflescopes the eyepiece focus mechanism it to focus the reticle ONLY, period. The parallax adjustment, if there is one, is to adjust out parallax at any given distance. Once you set your reticle focus with the eyepiece you should never have to focus it again.....until your eyes change as you get older.

On many riflescopes there is a diopter power adjustment as well, separate from the parallax adjustment. The diopter power adjustment is always on the eyepiece or ocular, the same place on binos.

It is possible your eyes have some uncorrected refractive error if you need to adjust every time you pick up a pair of binos from someone else. I will agree the adjustment should be made when first using the binis, but if you make that adjustment and then hand the binos to me i should not HAVE to make the same adjustment to my eyes assuming we both have fully corrected distant vision. Even if you have a small amount of correction in your eyes that is uncorrected, the thing you are describing where you balance the eyes together is what i was referring to first, anisometropia where one eye power is off from the other. I am very sensitive to that since i use microscopes and optics all day, but a lot of people do not notice it. The reason you have to make that adjustment is because the diopter power is different for each eye. But once adjusted properly, it should not need adjusted between users.

I believe we are talking about the same thing but it is possible we are confusing terms. I could be wrong.

Once I set my binos up the way I described, I don't have to adjust them again. That's why you set them up correctly in the first place. When they're set up for my eyes, and you pick them up, you will have to follow the same steps as I did to adjust them to your eyes, period. That's the way binos work.

The power ring on a rifle scope is just that, a power ring, not a diopter power ring and it resides on the main tube, not the eyepiece. It adjusts the power setting and that's it. I have no idea how you come up with this nonsense of adjusting the binoculars once, then it's set for everyone else who wants to look through it. That's why the diopter ring adjustment, whether by the main focus ring or on the right eyepiece is there, to adjust for each individual's eyesight.

Again my method and of setting binoculars and experience that it is different for almost everyone is exactly as JGraider describes. The only time that’s not true is when the user doesn’t understand the program and they look through blurry glass thinking that’s just the way it is.

We’re (I’m ) still missing something here and I appreciate the attempt at making me understand.

I’m going to keep with my program. It works and I see well with no eye fatigue.

I agree with that “program” too, and as stated it should be done the first time for anyone looking through binos.
Where we differ is saying ut needs to be done between people every time. My point is that should not “have” to be done between people who see well at distance and should be interchangeable between folks whether they wear glasses or not. Once adjusted, it should be usable by anyone who has normal eyes.

The point anyone needs to do that after someone else has used the same pair of binos tells me that initial person did. Not understand the diopter power adjustment in the first place, which was my original point.

Again, i really think we are talking about the same thing. I am just saying if i handed you a pair of binos i had just used, you should NOT have to adjust the diopter power to use those binos, assuming your eyes are the same and you dont have a difference in prescription between the eyes.

It tells me you don't understand how binocular adjustments and what they do, work, and the simple fact is that the vast majority of people young and old don't have "normal" eyesight. The fact that you keep referring to this gizmo as a "diopter power adjustment' keeps me shaking my head. I'm through trying to explain it to you though, so have a good one.

Swarovski NL pure technical page

I call it what the manufacturers call it. Look at the link and see what it is called (10 rows down, the value is +\- 4 diopters for all the NL pures). It isnt a gizmo either, it is a power adjustment for optics to account for refractive error if ypu plan to use the binos without visual correction. These diopter adjustments are on almost all of my day to day work equipment so i know what they do, and if adjusted correctly should not need to be adjusted from a normal person’s eyes to another normal person’s eyes.

The fact you need to adjust this all the time when looking thru some one else’s binos tells me either they were not adjusted correctly for that person, OR your eyes have a difference in power that you need to account for. My guess is the former, but who knows.

One final note, when i say “normal eyes” i am referring to distant corrected vision. I dont need correction but that would not impact my ability to use binos from someone who had glasses that corrected for distance vision correctly, and vice versa. While there are a lot of people who wear glasses and contacts, if they are fully corrected for distance it is a moot point from a diopter adjustment standpoint.

Well me and my cohorts look like 3 blind mice, we have to adjust to get it right.

Agreed. In 53 years of hunting I've never had it any other way. In Ohio it's apparently different than the real world.



I read 10 rows down, and Swaro refers to it as a diopter, just as I said, not a "power adjustment diopter", which it isn't.

I am not trying to be a know it all with this, but please look up what a diopter is, and you will see it is a unit of refractive power. So “diopter adjustment” is synonymous with “diopter power adjustment”.

Terminology matters, and if you dont know what terminology mean, its easy to look up.

You can look at any optics owner's manual from any optics maker/reseller and the term "diopter power adjustment" will not be in any of them. It will say "diopter". It's not even arguable, neither is the way you set them for each individual's eyes. Hasn't changed in decades but believe what you want.

In my 60's now and only need low power transition glasses. I do like having my transitions on when shooting my rifles. I absolutely hate having glasses when using my binoculars. On with scopes off with binos!

I'm nearsighted and can see iron sights perfectly without my glasses but not near as good with them. Thankfully, I can read and do close work without glasses and will often leave the ones I use for seeing distance on my forehead, even though it agitates my wife. I feel comfortable hunting with iron sights out to about 40 yards but that's when it becomes too difficult to see the sights clearly enough for sufficient aim. No issues whatsoever when using a scope.

Take this to the bank.

As stated, the ocular is focused on the plane of the reticle and that means that the portion of the image that is in that same plane is also in focus. When you turn an adjustable objective a side-focus knob, you're moving the image to and fro within the erector where the reticle is. Parallax is cancelled when the object of interest is moved into the same plane as the reticle.

Think of the image you see in your scope as a tiny hologram. It has depth, and only a single slice of it can be in the same plane as the reticle. The solution is to move the "hologram" to and fro in the tube to place the object of interest into the same plane as the reticle, thereby eliminating parallax.

cataract surgery before 80 so no glasses for driving or shooting.

If you wear glasses then eye relief is your friend.