Question for Eyeglass wearers

[GrillBoss]

Last night we had crystal clear skies but it was too cold for a long session (-33 degrees) so I brought out my binoculars for some short observing sessions.  I have had these Zeiss 10x40 binoculars for more than 30 years and I always had best results using them without my eyeglasses on and the eyecups extended out.  When I use them on terrestrial objects I still get good results, but recently I started viewing celestial objects with them and I notice a bit of a double image.  I adjust the front dial (diopter?) as far as it will go but I can never resolve to a good single pinpoint image.

Since these are high quality binoculars I assume the problem is with my eyes, likely astigmatism.  I have tried wearing glasses while I view but I can't seem to get consistent sharp views.  I think the problem may be that I am wearing "progressive" lenses, which are a multi-focal design.  I am looking for some input from experienced viewers who wear glasses.  Do I need a pair of "single vision" reading glasses for observing with binoculars?  Do you have the eyecups extended or rolled down when you view with glasses?  Any tips are appreciated.

[Captain Scarlet]

I can’t answer all the questions but I do use binoculars with glasses on. I invariably have the eyecups in the “most down” position. Some binoculars I’ve rejected because the eye-relief is less than the distance from the eyepiece lens to my pupil with glasses on. Sometimes much less. For glasses-wearers, eye-relief is a very important parameter of a given set of bins. I’ve always eschewed dual-focus glasses for exactly the reason you describe: potential for double-images.

I should add that some very expensive and high quality binoculars simply have short eye-relief and therefore exclude use by any glasses-wearers 🙄. I recently sold a pair of 10x32 Leica Ultravids for exactly that reason when I finally understood why I never got on with them.

Magnus

Edited January 3, 2022 by Captain Magenta

[Broadymike]

I'm a wearer of glasses and have never found a pair of bins that I could use well with glasses on day or night. I've always relied on using the adjustment for the one eyepiece to match the focus of my eyes then use the main focuser to focus on my target. I have astigmatism in one eye but doesn't seem to affect me that much. 

 

I did however get given a pair of bins a few years ago and struggled to get a good clean image. The problem ended up being one of the tubes had been cross threaded at some point which had thrown the alignment right out. Once I rectified this they have been my goto 10x50s ever since. 

[StarryEyed]

I think the problem is its - 33 degrees and one of your eyeballs has frozen. 

[Stu]

8 hours ago, Broadymike said:

goto 10x50s

Goto binoculars, they sound very useful 😉😉

On 01/01/2022 at 15:21, GrillBoss said:

Do I need a pair of "single vision" reading glasses for observing with binoculars?  Do you have the eyecups extended or rolled down when you view with glasses?  Any tips are appreciated.

I would say yes. Using bifocal or varifocal glasses with binoculars is likely to be a cause of your problems. Is there a reason why you can’t go back to using them without glasses?

In general I use my binos without glasses and with the eye guards fully extended. A lot will depend on how much eye relief they have, but using them with glasses will likely need them either fully or partially rolled down depending on the type of eye guards you have.

[Cosmic Geoff]

I use my cheap 10x50 bresser binoulars while wearing varifocals.

As for the double image, seeing two stars where there should be one is a symptom of the binoculars needing collimation. This happened with my Berssers, and this issue is more obvious when looking at stars, than in the daytime when your eyes will find it easier to combine the images.

[Pixies]

Yep - double image normally means a collimation/alignment problem. As Geoff says - it's more obvious when looking at stars.

Now - perhaps something has happened to your binos recently, to knock out the alignment. But here's a respectful thought.... Slight mis-collimation and double-images can be overcome by your eyes compensating, although it can cause eyestrain and headaches. As one ages, your ability to do this diminishes! You've had these binos for 30 years? you've had your eyes a bit longer, I guess!

 

[GrillBoss]

Thank you for the feedback.  I have a new pair of Pentax 16x50 on the way as well as a Fuji Glimpz 5x21 ($30!) and a Nikon AE 7x35.  Once I have enough binoculars to compare I should be able to figure out if the problem is my eyes or the binos.  

[RT65CB-SWL]

I never wear my glasses/spectacles with my binoculars or ‘scopes and/or camera [DSLR & digital-compact] viewfinder, unless I am reading the camera menus/settings screens.

[Carbon Brush]

Varifocal specs, with any significant astig and near/far correction are full to the brim with compromises.

Near enough being good enough for daylight use. Lots of light so the pupil is small and your brain having full screens available for processing.

But at night, you easily put the light path through a differently corrected region in each lens.
Then your brain has to work out which bright dots should be coincident.
In extreme conditions, even two moons to blend!

Day or night, my specs are off for binoculars.
For serious night viewing the sky, whether one eye or both, it is contact lenses.

The other effect is if you are tired. Eyes can easily drift off a bit in different directions.

You didn't specify C or F for -33deg. Not that they are far apart at that point.
Certainly colder than the UK has seen in the past 10000 years since we had mammoths wandering about on glaciers🥶

 

 

[Louis D]

If you don't have strong astigmatism in your eyes, you don't really need to wear eyeglasses with binoculars.  Sure, leaving them on can speed up looking at the sky naked eye, and then quickly switching to binoculars without having to take off your eyeglasses first.

To diagnose your issue, take off your eyeglasses and then start by focusing the binoculars by closing the eye with the diopter adjustment and focusing through the other eye.  Next, close the first eye and use only the diopter adjustment to focus for the other eye.  Now open both eyes.  You should see two equally sharp images.  If you have astigmatism, you'll see a slightly blurry image in the daytime or spiky stars at night.

Now, close alternating eyes and see if the image jumps between two positions or remains stable regardless of which eye is viewing.  If you see the image jumping about, your binoculars need collimation.

Put your eyeglasses back on and repeat the above steps.  Do you see any differences?

There is a very slight possibility that your eyeglasses have prism correction which allows you to merge misaligned images naked eye.  However, you'd probably be well aware of it since it is usually diagnosed at a young age.  That, and you'd see double images without eyeglasses or binoculars.

[HarryLP]

Not sure if this is the right place for this but let me add my current experiences with binoculars.

I have astigmatism of -1.25 in both eyes which I believe is in low end mild level. I mainly wear torric contact lens during the day and varifocals at night. I observe naked eye.

I have 10X50 'lidl' binos which are excellent during daylight with or without contacts but virtually impossible to obtain a merged single astro image with at night, with or without contacts.

Amazon have just had their spring sale and I purchased Celestron 25x70 Skymasters hoping that the bigger adjustment range would help. I also wanted a decent pair to encourage me out more, as over the last six months the cloud cover has been so bad it's not been worth getting the dob out.

Not had a lot of time to fully test...too much cloud cover.

Daytime use seems problem free, including a faint washed out daytime moon yesterday. Managed 30 mins of dark time on the moon about 2200 last night. Managed to get the moon to a single image and then on closer inspection noticed a degree of double images on the moon's surface which I sort of resolved ? Played around with focus and IPD and then not 100% certain if I was fully viewing through both eyes.

Need some better dark time to more fully evaluate.

Any comments, suggestions, insight very welcome.