Glasses or No Glasses?

[Hayduke27]

I am near sighted, and have to wear glasses to see anything at a distance in detail. However, when I am viewing through optics such as my binoculars or spotting scope, I don't use glasses as it seems I can just adjust the focus of the equipment to compensate for my vision. 

 

I see references on here frequently about people who feel like they need to wear glasses when viewing through their telescope.  Is there a benefit to glasses?  It seems to me that it's pretty much easier across the board to view without them when looking through an EP, and can't you adjust the focus to make the image clear despite imperfections in our eyeballs?  Am I missing something here? 

[Astro Imp]

Providing you do not suffer with astigmatism viewing without glasses is fine however I find it frustrating to keep taking them on and off to refer to sky charts etc.

I guess like a lot of things it comes down to personal choice and convenience.

 

[wookie1965]

I use something like this so saves me from searching round in the dark for my glasses. 

www.amazon.co.uk/gp/aw/d/B00QNS6QT2/ref=mp_s_a_1_1?ie=UTF8&qid=1508511946&sr=1-1&pi=SL140_SY180_CR0,0,140,180

[Tim]

10 minutes ago, wookie1965 said:

I use something like this so saves me from searching round in the dark for my glasses. 

www.amazon.co.uk/gp/aw/d/B00QNS6QT2/ref=mp_s_a_1_1?ie=UTF8&qid=1508511946&sr=1-1&pi=SL140_SY180_CR0,0,140,180

Ah me too, they are still a bit of a pain swinging around but I need them to read my handset, Wixey, and the star maps, and once they are put down somewhere they just walk around, i'm sure of that........ I have slight astigmatism, but do not wear glasses to observe with as the effect is negligible.

Smaller exit pupils of higher magnification EP's can negate astigmatism anyway I think, but for my higher power EP's I find the Televue Delos range with adjustable eye relief can work quite well even with glasses on if the need arises.

It can be quite interesting when sharing a dob to see how much other people have to alter focus to match their eyes.

[Ouroboros]

Ditto for the convenience of using a spectacle cord or lanyard. Picked mine up in Boots I think. 

I've never been able to observe through bins or telescope with glasses on. I'm slightly astigmatic too but that doesn't seem to matter. 

[Gina]

I have short sight and astigmatism in both eyes and glasses are awkward for observing so I don't.  I do imaging instead

[Buzzard75]

I'm a contact wearer myself. I actually take my contacts out before a viewing session because often times they start bothering me after a long day and an even longer night of wearing them. So I wear my glasses.

I don't have astigmatism, but most of the eyepieces I use offer enough relief that I can wear them during viewing. Those are really the two main determining factors. If I don't have a long relief eyepiece, I'll take them off and refocus as necessary.

[D Brewer]

I find glasses a nuisance especially on cold nights when they steam up

 

[JOC]

Whilst I hate them I have worn glasses for over 30 years.  I have tried to view through the EP without them and yes I can reach focus though I am aware that the astigmatism is harder to accommodate.  I guess I can view through the telescope adequately without them, but I become very aware that I don't have them on and as the others have said there are periodic occasions where you need to be able to see when you are not looking through the EP and I def. can't manage without them in those situations.  It is almost as I though I don't think I can see through the EP when I am not wearing them and this is sufficient of a distraction that I tend to use them for viewing.

[D Brewer]

It's just a matter of what you are used to I kept hitting my glasses on the eyepiece when I first got my scope 

[Stub Mandrel]

My astigmatism in one eye is mild enough not to cause a problem - most people who don't wear glasses have a similar amount.

BUT I struggle with eyepieces although I'm gradually getting better. Very hard swapping them on and off all the time but can't do other things without them, especially in the dark! Eyes bad enough that with glasses off my bins are right at the extreme of their adjustment which is an issue of its own.

[des anderson]

Glasses are such a pain.....On a personal note I use a lanyard it saves all that bother of putting them down trying to find them. Des

[Horatio]

umm...

I'm blind as a bat (just what you need for astronomy) I'm minus 8.75 in my good eye, yes you heard correct, my good eye!  I'm minus 10 in my duff one (right eye) and have a scleral buckle (implant) to hold this one altogether after a detached retina op, gives me an image but blurred one and a bit distorted too, thing is I'm right eyed dominant but now through necessity changing to EP viewing through my good eye...lol.

I've tried viewing wearing contacts, good through the EP, hopeless at star hoping (don't have a goto...one on order now though) and viewing anything like safari on my phone forget it ..  With my bottle ends on, it's much better for star hoping and reading phone aps, I take them off to view through the EP and adjust focus, thing is though I'm finding it very difficult using finder scope as I keep them on and try to use two eyes, one star hoping the other lining up through finder.  To remedy this I'm going dual finder, and having a red dot and low mag finder.  Hopefully this will do the trick.

So after trial and error, glasses on for me. 

This may change and may be able to go contact lenses when I get my goto but with contacts you never get your prescription its always weaker and with my 'mince pies' I need as much help as I can get.  I am an extreme case but I'm guessing they're are worse.

 

[Charic]

I have to wear prescriptions for driving, but choose not to wear them  at the scope, and only the TELRAD (sold) failed me by not wearing them!
Wearing glasses whilst just looking up is sharper than without, but behind any eyepiece, I feel most comfortable without the glasses.
My left eye is sharper than my right, and even tried to use the left eye only, but just doesn't feel right. Do whatever you need to get the best view.

[JOC]

It must be awkward to use just one eye for something like astronomy or shooting if you are wearing what I will term 'bifocal' contact lenses, this is when one eye wears a distance lens and the other wears a short distance lens and the brain compensates!

[Louis D]

Astigmatism may become visible at larger exit pupils.  Televue's DIOPTRX page has a nice diagram showing the likely visibility.  I have 2 diopters of astigmatism in my dominant eye, so I can only tolerate a 1mm exit pupil without them.  Even at that, I still get a slight sharpening of pinpoints of light with eyeglasses.

I wear eyeglasses at all times at the eyepiece.  It's also handy when sharing the view to be focused for infinity corrected vision so anyone else with infinity corrected vision will not have to refocus (much) to see a sharp image in the eyepiece.  Too many newbies are reluctant to refocus unfamiliar telescopes to bring it to focus, so this saves them from that.  I always tell people to leave their eyeglasses on so they'll get a sharp image.

2 hours ago, D Brewer said:

I find glasses a nuisance especially on cold nights when they steam up

 

I find just the opposite.  Without eyeglasses, my eyepieces fog up because there's no vapor barrier between them and my moist eyeballs.  Eyepieces tend to chill off to whatever the ambient temperature is because of their high metal content, so any moisture immediately forms dew on the eye lens.  My eyeglasses don't tend to ever reach ambient temperature so they don't tend to fog.  The lone exception is when wearing a balaclava and moisture from my breathing is funnelled upward to my glasses.  Then they will fog.

[Louis D]

29 minutes ago, JOC said:

It must be awkward to use just one eye for something like astronomy or shooting if you are wearing what I will term 'bifocal' contact lenses, this is when one eye wears a distance lens and the other wears a short distance lens and the brain compensates!

This sounds similar to a CN contributor who had his bifocals set for 4 different correction distances.  It took him forever to convince his eye doctor to write him the prescription that way.

[Scooot]

Astigmatism is a real nuisance, I have to wear my specs to view through my binoculars, but I have to take them off to read. However I use a Dioptrx to view through the scope without my specs, but then I have to put them on to see the sky. Off on, off on ........ I put an old pair in a pocket as they’re vulnerable to damage ? 

[JOC]

I guess what you are having to focus on is the image appearing on the surface of the glass at the eye side of the EP, i.e. that distance that the eye-relief is measured to on an EP.  Presumably you adjust the focus of the EP to place a crisp image on the EP top lens surface.  Therefore presumably what you want is close up spectacle lenses to see that distance?  With varifocals this is awkward as the close up part is one on part of the lens surface.

[Piero]

I use them while finding targets, but once the target is in the eyepiece, I take them off. Unless you suffer from astigmatism, you don't need them. 

[Hayduke27]

I actually do have astigmatism in both eyes, and I have tried viewing both with and without glasses.  At first I swore that I saw no difference either way, but lately I've been thinking it's slightly easier to get things in focus when my glasses are on.  With some EPs I feel like I can see a wider field of view when I take the glasses off and get a little closer, and I'm constantly bumping my glasses on the EPs.  

Very interesting to hear all of your thoughts on this.  I'll have to keep experimenting and see what works best.  I will be viewing in some extreme cold, and I kind of like the idea of keeping my glasses on as a buffer between my eye and EP.  Fog quickly turns to frost up here, and that can end a viewing session.

 

Thanks for all of your replies!

[Scooot]

Yes, one snag of using a Dioptrx is I have to have the eye guard down to see the full Fov on the Ethos & Nagler,  which means as @Louis Dabove said, my eye is so near the glass it’s a struggle to keep it clear of mist sometimes. I can have the eye guard up on the Delos so it’s not a problem with these.

[Louis D]

4 hours ago, JOC said:

I guess what you are having to focus on is the image appearing on the surface of the glass at the eye side of the EP, i.e. that distance that the eye-relief is measured to on an EP.  Presumably you adjust the focus of the EP to place a crisp image on the EP top lens surface.  Therefore presumably what you want is close up spectacle lenses to see that distance?  With varifocals this is awkward as the close up part is one on part of the lens surface.

What you're describing would be focusing an image on something akin to a ground glass focusing screen as in an old fashioned view camera.  That is not what's happening when you focus an eyepiece for your eye.  I'm no expert on the subject, but you're basically transferring the real image at the focal plane of the telescope and creating a virtual image in space at the eye relief point that requires another system of lenses, your cornea and focusing lens behind it in your eye, to then translate this virtual image into a real image onto your retina.  The focuser, given enough travel distance, can create a virtual image seeming to appear at infinity, beyond infinity (whatever that means), or very close.  The first one is the mode I take advantage of at star parties since most everyone has access to infinity corrected vision.  The last one would be the mode myopic folks would use to view without eyeglasses.  Maybe far sighted folks would use the middle one?

You're spot on about varifocals.  There's no way the entire field of view will ever be in focus at once when viewing through them.  That's why I use dedicated single vision lenses set for infinity focus at the eyepiece.

5 hours ago, Scooot said:

I put an old pair in a pocket as they’re vulnerable to damage ?

I used to use an old pair of single vision eyeglasses at the eyepiece until I realized two things wrong with this approach:

1. The astigmatism correction was off due to my prescription having shifted over time, so I kept thinking my expensive eyepieces had residual astigmatism across the field.

2. These old eyeglasses had micro and macro scratches all over them that weren't visible normally, but showed up quite clearly at tiny exit pupils that hit them like tiny laser beams and scattered the light rays.  This interference would totally destroy any image fidelity.

To solve this issue, I bought a good quality pair of low index single vision infinity corrected glasses for cheap online.  It turns out, most of the markup on eyeglasses is for the designer frames and to cover brick and mortar overhead.  Since I'm wearing them in the dark, I don't care how they look on me, just how the world looks through them.  These eyeglasses are never worn for any other purpose to preserve the eye lens from damage.  I wanted to get glass lenses because they're virtually impossible to scratch compared to plastic/polycarbonate lenses, but no one seems to sell them anymore. It probably has to do with the liability associated with them shattering on impact and possibly blinding the wearer.  I figured my chances of shattering them at the eyepiece to be pretty low unless some joker came up behind me and smashed my head forward into the eyepiece.

[Fypunky]

On 10/20/2017 at 21:14, JOC said:

It must be awkward to use just one eye for something like astronomy or shooting if you are wearing what I will term 'bifocal' contact lenses, this is when one eye wears a distance lens and the other wears a short distance lens and the brain compensates!

Perhaps I can help as this is what I do on a daily basis...

JOC to a certain extent has the answer! We call it mono-vision, it can be achieved either by using daily contact lenses or lazer eye surgery, Cilla Black was myopic and that's what they did for her.

Not everybody can cope with it, most do.

I use a daily contact lens in my right eye as that is the dominant eye and leave my left myopic (short sighted) this allows me to still use the telrad if needed and also see the stars above but also allows me to see anything close up ( I am just starting with presbyopia(needing reading correction))

The reason I suggest Daily lenses rather than others is unless you are really lucky and observe every single night then lets say a monthly lens would sit in cleaning solution for days/ weeks and may never actually get used before you have to throw it away, with dailies you buy a box of 30, and use as and when so that box may last you several months.

Of course this is prescription/ patient suitable.

Might be worth having a chat with your optometrist as to options available.

On a less cosmetic option you can purchase here in the UK so I am sure you can get them in the US, make up glasses, these have a lens which lifts up to apply eye make up, I did try it and it worked, lens down position for viewing sky with naked eye and up for viewing in EP. There are all sorts of spectacle option available which have been designed for other sports that you can use.

Edit: Even with astigmatism this would work but again depending on the cyl power of the eye, you can get Toric lenses in a daily format, they are more expensive but then if a box of 30 is last two or more moths it may not be too bad.

[Louis D]

2 hours ago, Fypunky said:

Edit: Even with astigmatism this would work but again depending on the cyl power of the eye, you can get Toric lenses in a daily format, they are more expensive but then if a box of 30 is last two or more moths it may not be too bad.

I thought that Toric lenses were  orientation sensitive.  The bottom is thicker to help rotate them into the proper position using gravity.  If you tend to look downward into an eyepiece, they tend to rotate every which way negating any useful correction.