Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Eye Strain Issues in Binoculars - What's the right Fix?

Eyepieces Binoculars
  • Please log in to reply
18 replies to this topic

#1 AaronLatif

AaronLatif

    Lift Off

  • -----
  • topic starter
  • Posts: 11
  • Joined: 29 Aug 2020

Posted 11 April 2021 - 04:14 PM

I was facing severe eyestrain with my pair and then I started searching. I also wear eyeglasses, so it's even a bigger problem for me. 

I've read this following article where they suggested to use 16mm to 24mm eye relief binoculars for glass wearers. Is this the right option or is there any other way around?



#2 swsantos

swsantos

    Messenger

  • *****
  • Posts: 436
  • Joined: 29 Sep 2005
  • Loc: Rhode Island

Posted 11 April 2021 - 04:31 PM

I would think that eyestrain with binoculars is more likely either the oculars not being properly individually focused or the binoculars being out of collimation.

 

I do not feel that eye relief would impact actual eyestrain meaning focusing strain and that the "strain" referred to in that article regarding "strain the eyes to see the entire field" means fighting to get close to the exit pupil with glasses on using a short eye relief system.


Edited by swsantos, 11 April 2021 - 04:31 PM.

  • KennyJ, paul hart, Jon Isaacs and 6 others like this

#3 M11Mike

M11Mike

    Apollo

  • *****
  • Posts: 1,103
  • Joined: 02 Apr 2016
  • Loc: Ballston Lake, NY

Posted 11 April 2021 - 05:10 PM

IMO - your binos are out of collimation. 

 

Many lower priced binos are even when brand new.

 

M11Mike  


  • swsantos, SMark and ShaulaB like this

#4 Rich V.

Rich V.

    Cosmos

  • *****
  • Posts: 7,730
  • Joined: 02 Jan 2005
  • Loc: Lake Tahoe area, Nevada

Posted 11 April 2021 - 05:58 PM

The greatest cause of eye strain with binoculars is their being out of collimation.  Even if you don't see obvious double images, a misalignment could be forcing your eyes to strain to merge the two images, particularly if the misalignment is vertical or divergent (wall eyed); your eyes have very little ability to correct for those situations.  They deal with horizontally convergent misalignment much easier, just like reading a book or looking at anything close-up, but the ideal solution with binos is proper collimation.

 

Improper focus or IPD setting will cause you problems, but you have easy means to adjust them.  Binos with too little eye relief will only prevent you from seeing the entire FOV, but not eye strain.

 

Rich


  • Jon Isaacs, BRCoz and SMark like this

#5 paul hart

paul hart

    Surveyor 1

  • *****
  • Posts: 1,825
  • Joined: 01 Jun 2004
  • Loc: 50 M East of NYC

Posted 11 April 2021 - 06:00 PM

I agree the most likely cause is the binoculars are out of collimation.

 

https://www.youtube....h?v=kygO9VhKxIM



#6 TOMDEY

TOMDEY

    Cosmos

  • *****
  • Posts: 9,770
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 11 April 2021 - 06:03 PM

Two most likely contributors to binocular eye-strain >>>

 

1) That your binos are poorly-collimated

2) That you have undiagnosed prism in your eyes or glasses

 

If it's been awhile (a year of more) sensible to get your eyes and current glasses checked by a ~full-service~ optometrist. Specifically mention the eye strain that you are experiencing. He will quantify your prism and see if explains things. We all should get our precious eyes checked annually anyway. If your eyes check out OK, then it is the binos that are to blame. Get them repaired or just get better good ones. That's really all there is to it!   Tom

 

[Eye health is sorely neglected by most people... most especially... astronomers!]



#7 sevenofnine

sevenofnine

    Viking 1

  • -----
  • Posts: 975
  • Joined: 16 Apr 2016
  • Loc: Santa Rosa, California

Posted 11 April 2021 - 06:18 PM

There are many reasons for eye strain when using binoculars. If the binoculars are low end price wise (<$150) they are suspect. If they are decent quality, make sure that they are adjusted to your eyesight and are in collimation. If you are using binoculars for long periods at a time only the best will cause no eye strain IMO. Good luck! watching.gif  



#8 ran7621

ran7621

    Explorer 1

  • -----
  • Posts: 50
  • Joined: 21 Jan 2009
  • Loc: Souther California

Posted 11 April 2021 - 06:23 PM

Is there another pair of binoculars that you can look through? If you have the same type of issue in another pair at least we can rule out collimation issues.

Also are you experiencing this during the day or at night? I have very light sensitive eyes and experience eye strain in bright sunlight. If you look through the binoculars during daytime try cupping your hands around the eye pieces and see if that helps.

#9 Tony Flanders

Tony Flanders

    Hubble

  • *****
  • Posts: 19,689
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 11 April 2021 - 07:57 PM

As everyone here has said, bad collimation is pretty much guaranteed to cause eye strain and/or headaches. But some people get eye strain from any binoculars; they just have trouble fusing the images. I do OK, but I never find binoculars quite as comfortable as a single-eyepiece telescope.

 

I prefer using binoculars with my glasses on, partly because I have pretty severe astigmatism, and partly because I like to correlate the binocular view with the naked-eye view, which is best when I am wearing glasses. And using glasses with binos definitely requires long eye relief.


  • Jon Isaacs and SMark like this

#10 JuergenB

JuergenB

    Ranger 4

  • -----
  • Posts: 345
  • Joined: 15 Nov 2015
  • Loc: Lilienthal, Germany

Posted 13 April 2021 - 11:17 AM

Almost everything was already written here, but I would like to emphasize on the rule that you should always focus from outwards (extrafocal) to the best focus point, not from inwards (intrafocal). That way, your eyes will be more relaxed.

 

Juergen


  • ButterFly likes this

#11 Foss

Foss

    Viking 1

  • *****
  • Posts: 907
  • Joined: 20 Feb 2012

Posted 13 April 2021 - 08:48 PM

Hi Juergen,

Will you give me an example please?

~ Jack



#12 PEterW

PEterW

    Mercury-Atlas

  • *****
  • Posts: 2,622
  • Joined: 02 Jan 2006
  • Loc: SW London, UK

Posted 14 April 2021 - 01:26 AM

If you want to nail focus it’s best to approach from both sides, noting where the best focus is on the focusser. Sometimes your eyes do the last bit of focus correcrion for you. This is most pronounced when adjusting the diopter correction as you want both eyes to be receive equally focussed images. I assume the OP has set the diopter adjustment?

Peter

#13 25585

25585

    Voyager 1

  • *****
  • Posts: 13,160
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the SW UK. Dark end of the street.

Posted 14 April 2021 - 06:02 AM

As I wear glasses for astigmatism correction, I have min of 19mm eye relief on all the binoculars I use. But as with telescope eyepieces, finicky exit pupil behaviour can cause eye strain as well as optical design issues.

 

I find widefield binoculars the worst and standard or narrower field most comfortable.



#14 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 92,792
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 14 April 2021 - 09:24 AM

As I wear glasses for astigmatism correction, I have min of 19mm eye relief on all the binoculars I use. But as with telescope eyepieces, finicky exit pupil behaviour can cause eye strain as well as optical design issues.

 

I find widefield binoculars the worst and standard or narrower field most comfortable.

 

Wearing glasses adds another level of optics and optical alignment difficulties that can make things even more finicky.  I've experimented with wearing glasses just to see the challenges others face, it's not easy. 

 

I'm fortunate and do not need to wear glasses when viewing, eye strain is not an issue for me. 

 

Jon



#15 JuergenB

JuergenB

    Ranger 4

  • -----
  • Posts: 345
  • Joined: 15 Nov 2015
  • Loc: Lilienthal, Germany

Posted 14 April 2021 - 11:57 AM

Hi Juergen,

Will you give me an example please?

~ Jack

 

 

 

Hi Jack,

 

When you approach focus from the intrafocal side, your eyes will be able to accomodate before reaching the focal point of the telescope. It is a similar situation as observing a nearby object - the eye focusing muscles are not relaxed.

 

On the other hand, when you approach focus from the extrafocal side, your eyes are not able to accomodate prematurely. When reaching exact focus, your eyes will be relaxed as if looking at an object at infinity.

 

Of course you may judge the focus from both sides, but the last move should always be inwards.

 

Juergen



#16 gwlee

gwlee

    Mercury-Atlas

  • *****
  • Posts: 2,751
  • Joined: 06 Sep 2015
  • Loc: 38N 120W

Posted 18 April 2021 - 01:56 PM

Hi Jack,

 

When you approach focus from the intrafocal side, your eyes will be able to accomodate before reaching the focal point of the telescope. It is a similar situation as observing a nearby object - the eye focusing muscles are not relaxed.

 

On the other hand, when you approach focus from the extrafocal side, your eyes are not able to accomodate prematurely. When reaching exact focus, your eyes will be relaxed as if looking at an object at infinity.

 

Of course you may judge the focus from both sides, but the last move should always be inwards.

 

Juergen

What’s missing is definition of “extrafocal.”



#17 JuergenB

JuergenB

    Ranger 4

  • -----
  • Posts: 345
  • Joined: 15 Nov 2015
  • Loc: Lilienthal, Germany

Posted 18 April 2021 - 04:17 PM

What’s missing is definition of “extrafocal.”

I gave the explanation in post #10. "Extrafocal" may also be described as "focal point of the eyepiece being beyond the focal point of the objective, in the direction towards the observer".



#18 oldmanrick

oldmanrick

    Viking 1

  • *****
  • Posts: 811
  • Joined: 30 Jul 2015
  • Loc: Western Montana, USA

Posted 22 April 2021 - 07:15 PM

All very good answers above, to a common and bothersome situation.

 

However, the contrarian in me is urging me to gain information and insight into a term commonly used when talking about binocular usability and adjustment.  My belief is that the term "collimation", as frequently used in this thread is technically incorrect.  In my understanding of optical terms, "collimation" refers to how well collimated, or aligned the optical path is within and individual optical tube or light path for an optical instrument.  For a binocular, this would mean how well the photons aligned by the objective lenses were aimed to properly pass through the prisms and be properly centered in the eyepiece of each individual tube of the binocular.

 

As used in this thread, the word "collimation" is used to describe how well the projected image coming out of one eyepiece matches the aim of the similar image coming out of the other eyepiece.  This relates how well each tube is aligned with the other to project the light stream from a star, planet or other target to the same focal point, so both of our eyes can easily see the same target in the same place from each barrel.

 

When this aim is different, we see double images, or else our eyes and brain have to strain to merge the two errant images into one useable image.  Thus eyestrain or brain strain and headaches can result.

 

I believe that the word "alignment" more properly describes how well the individual binocular tubes are aligned with each other to provide an easily resolvable image for our eyes, rather than "collimation" as commonly used to describe this condition when discussing binoculars.

 

Please correct me if I am wrong!

 

Rick



#19 ran7621

ran7621

    Explorer 1

  • -----
  • Posts: 50
  • Joined: 21 Jan 2009
  • Loc: Souther California

Posted 23 April 2021 - 11:01 PM

col·li·mate
/ˈkäləˌmāt/
verb
make (rays of light or particles) accurately parallel.
"the cesium atoms are collimated into a narrow beam"
accurately align (an optical or other system).
"manuals give detailed instructions for collimating the optics"

 

 

I think it is fine to use this word to say one tube is aligned with the other




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: Eyepieces, Binoculars



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics