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Problem with focusing /diopter setting

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#26 Sarah88


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Posted 06 December 2005 - 02:16 PM

Something you touched on there Kenny - CAPPING the eyepiece instead of closing one eye.

I can't 'wink' my right eye (I've never been able to do it) so once or twice I have held my eyelid shut with my fingers (instead of capping) and when I released it I found that my right eye was way out of focus, and took a few minutes to go back to normal - I assumed that I had 'squashed' that eye slightly, and it needed a few mins to go back into shape.

Maybe winking one eye shut does the same thing? (to a lesser degree)
Which would explain why it is better to CAP than to WINK.

#27 KennyJ


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Posted 06 December 2005 - 02:35 PM

< Which would explain why it is better to CAP than to WINK.

Sarah ,

Re - capping , and to winkle out every detail of what I was trying to explain , I think much depends on what is under the cap , and how different people respond to a wink :-)

Regards , Kenny

#28 Guest_**DONOTDELETE**_*

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Posted 06 December 2005 - 03:15 PM

I actually CAP the right objective , and leave BOTH eyes open while making that adjustment ( which IS absolutely CRITICAL to get RIGHT )

That's the correct way to do it (so I've been told), but I admit to have cheated sometimes and just closed the eye.

#29 BillC


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Posted 06 December 2005 - 11:30 PM

In these situations, when I mention that the observer MAY be focusing the wrong side first, I usually offend someone, unintentionally. However, since even a large number of Audubon members in the area don't know how to properly focus the bino they have been using for years, I am always willing to take a chance.

HOWEVER, there may be a BETTER reason. When focusing a bino, the brain wants to get down to the brass tacks rather quickly and will cause the muscles around the eyes to expand and contract to bring the object into focus.

This is artificial and can't be maintained, and leads to continued focusing.

when focusing, JUST STARE while turning the wheel or diopter ring. That way you can be sure the image is coming to YOU while your eyes are at rest. Once this is done, things should work pretty well throughout the focal range.



#30 johnno


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Posted 07 December 2005 - 05:44 AM

Hi Bill,
Thanks for the explaination on the correct way to set up the Binoculars,I am quite sure many of us will benefit.
I have allways
1 set dioptre to zero
2 cap right objective
3 adjust FOCUS wheel to best focus
4 cap left objective
5 adjust DIOPTRE for best focus

But,I did NOT KNOW, about just staring,to relax the eyes.


#31 JCB


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Posted 07 December 2005 - 07:44 AM

Very interesting thread !

I have noticed this strange fact with my Zeiss Classic 10x40. Between close distances and infinity, I must change the diopter setting by at least 1 diopter. I can observe this difference each time I use this bino, even with very careful settings (capping the objectives, turning the wheels in the right direction, doing the setting again several times, etc...). By the way, 1 diopter is a BIG difference, very easy to notice.

My Zeiss FL 10x42 has the same behaviour, but with much less severity.

With my two cheap Meade 10x50's, I don't need at all to change the diopter setting. When it is good, it is good for all distances.

Carefully, I won't suggest any explanation, in order to avoid the asylum.


#32 Claudio


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Posted 09 December 2005 - 05:38 AM

SOMETIMES , even with the SAME binocular , I need to adjust the right diopter DIFFERENTLY from what I might have done the previous day , to attain what I perceive as being PERFECT FOUCUS , even on an object at exactly the same distance !

I don't expect anyone to try to explain that , but it MUST be that some days my short - sightedness in my right eye is not as " slight " as it appears to be on other days .

There must be bio - chemical reasons for this .

Perhaps , for example , if I'm VERY tired , or my eyes have been focused on something close ( such as a PC screen ) for hours ( or even a combination of both ) then maybe the muscles in my eyes just cannot work hard enough to make the adjustment required to focus from close to far distance .

In ADDITION to this ( as if this isn't troublesome enough )SOME days ( and nights ) I've found myself having to do the same kind of thing which EdZ has described , altering the right dioptre to compensate for different distances , whereas on other days , everything seems to work just like all those minimilistic instruction leaflets suggest .

Kenny, the same happens to me, I think that your very interesting comments should deserve its own thread.

I find I have variations of the right dioptre of up to ½ dioptre (so not the huge variations other members report)

This has been happening to me since I was 45 (am 49 now).
Difficult to say what factors are more involved. However here are some thoughts:

- in the last 6 years I have been working too much with my PC, much more than in the previous years. Almost always I notice some difference in my sight when stop my work at the PC to observe a bird from the window

- I was 45 when I started to use reading glasses, thus since then my crystalline lenses work more lazily than before.

- In the last five years I have been using many different binoculars. Before I was using only a 7x50 and a 8x50, two glasses with large exit pupil. With them I have almost never had to re-touch the right ocular setting. Still today I find that binoculars with exit pupil larger than, say, 5 mm are less demanding (also) from this point of view.
Moreover, I think that if we use always the same binocular, eyes get more accustomed to it, I mean that in such a way your eyes are interacting with that binocular.

- I remember that 20 years ago I bought a Nikon 9x35, but after using it for a couple of months I decided it was not for me. Even if I was realizing it was a very good glass, fine optics, very good mechanics etc, I had not been able to find my RIGHT right eye adjustment. Certainly the not very wide sweet spot could contribute to cause this, but there was something more I was not able to understand. At that time my eyes were not so sluggish.

- In the last 3 or 4 years I perceive that, when I wake up, something doesn’t work perfectly in my eyes. Something very slight, probably unperceivable for other people and anyway almost not detectable until I look through a binocular. It happens to me for a short time, say an hour.

Well, any ophthalmologist or psychologist of the vision at Cloudy Nights?


#33 Guest_**DONOTDELETE**_*

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Posted 09 December 2005 - 08:21 AM

I am not surprised to hear about the difficulties..or rather...the differences people experience after staring at something like a monitor for a while. It is well known that people have conditioned themselves to be far or near sided by their eye usage. I would suspect this is related to what Claudio and Kenny have reported...and I would suspect that this would become worse for older people.

I have troubles using binoculars just after sleeping for while. I always need some time, like 30 mins to get my eyes in agreement, but this could be something entirely unrelated. It's just a quirk I have.

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