I am about to become an eyeglass wearer - what do I need to know about eyepieces?

[AEAJR (Ed)]

I started in astronomy in May, first looking at the sky, then binoculars and now telescopes.

As I have spent time with Jupiter specifically I came to realize that Jupiter is supposed to be a soft ball in the sky and through binoculars. It is not supposed to have any spikey legs to it. I checked in binos, 2 scopes and various eyepieces.

Then I realized that the reason stars are not pinpoints is not collimation or eyepieces, it is my eyes. Time to get the eyes checked. And there are other things telling me that I probably need glasses.

Saw the doctor. Need correction and have some astigmatism in both eyes. But overall pretty healthy. Ordered the glasses today.



Soooo, what should I know about observing with eyeglasses? This is going to be new to me. Aside from getting right of the spikey look I may be able to see more detail in Saturn and Jupiter and Mars.


I know eye relief is important but how much eye relief do I need? 12mm? 14 mm? More?

Anything else I need to consider besides eye relief?

Does one place the eyeglass lens on the eyepiece lens or should it be where I normally keep my eyeball?

Two of my most commonly used eyepieces are 9.7 and 6.4 mm plossls but they only have 5 mm and 2 mm eye relief. So I am probably going to need to replace them.

The rest of my eyepieces have at least 13 mm of eye relief so I hope they will be OK.


I am not looking to spend on new eyepieces if I don't need to but if I am going to need get them them I might as well ask for guidance now.

What do you think of the Explore Scientific 82 degree eyepieces in 6.7 and 11 mm. They are on sale right now, about 33% off in the USA. Typically 13mm or more eye relief. Good for eyeglass users?
http://agenaastro.com/explore-scient...ece-6-7mm.html


Agena Astro has Enhance Wide Angle, 66 degrees in 6 and 9 mm.
http://agenaastro.com/agena-1-25-ewa-eyepiece-set.html


Celestron X-Cel LX at 60 degrees seem to have good eye relief. I have been told these are the same as the Meade HD-60. I have the HD-60 4.5.
http://agenaastro.com/celestron-9mm-...ece-93423.html



Any thoughts from eye glass wearers would be appreciated. I am new at this.

[glend (Glen)]

Usual short or long sighted scripts do not require any 'special' approach as you just remove your glasses to observe and focus for your particular eye situation. However, Astigmatism can be different depending on the degree of it. If you have one eye with less than the other then make the lesser eye your observation eye. There are EPs that you can purchase with long eye relief, and it is possible to use these with glasses that correct astigmatism. You can buy astigmatism correcting EPs with a top diopter correcting element, or just buy the diopter element to attach to your EP. Televue make these, see this link:

https://www.astronomics.com/tele-vue...enses_c91.aspx


.

[AEAJR (Ed)]

How much eye relief is "long" eye relief? 12mm? 15 mm? 20 MM?

How long is long enough?

[inertia8 (Australia)]

I find >16mm comfortable, sometimes I have to push my eyeglass lense closer to my eye and have it touching the EP eyeguard to get the full FOV.

To this end I've ended up saving and acquiring long ER such as Pentax XW.

Personally I prefer to just leave my glasses on due to astigmatism and being able to look at the sky then move to the eyepiece, besides, no chance of getting your eyelash oil on the EP with your glasses in the way .

[rrussell1962]

Ed, it may be helpful to consider that the effects of astigmatism become less obvious with decreasing exit pupil size. The Televue website has a useful graph demonstrating this. How bad is the astigmatism in your observing eye? Mine is -1.25 and I don't really notice it with an exit pupil of around 2.5mm or less.

[The_bluester (Paul)]

Quite aside from the astronomical aspect.

As someone who got glasses for astigmatism at around age 30 (And subsequently went through laser correction some years later and have had nine years glasses free again now, though I forsee reading glasses in my future in the next few years)

Take it very easy when you drive until you get used to the glasses, I gave myself a bit of a fright soon after I got mine as they distort your vision (Undistort really) and in my case it messed with my depth perception a bit. I found myself having a nasty moment driving over a bridge with a corner in it at 100KMH (It was easily a 100KMH bridge) but the distortion of depth perception made it feel like the corner loomed at me very suddenly.

It only took about a week to get used to them and then it became a non issue but it is something to be aware of. I also felt a little like everything was leaning toward me until I got used to the glasses!

[dimithri86 (Dimithri)]

Hi Ed,

What is your prescription?

Mine is -0.5 of sphere which I compensate using the focuser (although other people look through a scope I focused and see it clear as well..so the effect might not be much), and I have -2.5 of astigmatism. I wear my glasses all the time, because otherwise the whole world is blurry, however through a telescope without eyeglasses everything is quite clear.

My wife is an optometrist and I've used her trial lenses to see that would make it even sharper, but it looks to make little if any difference.

Have a go, it might not too bad for you.

[AEAJR (Ed)]

Thanks everyone. I will get the glasses Saturday. They will be progressives and I am sure I am going to need a week or two to adjust.

I am not going to buy any new eyepieces until I see how I do with and without the glasses.

I have seen the Televue site and found that very interesting. Yes it seems that the astigmatism is less of an issue as the exit pupil decreases.

Will I want to keep my glasses on? Well, we will see.

My Agena SWA has 28 mm eye relief so I can try that with the glasses.
http://agenaastro.com/agena-38mm-sup...-eyepiece.html

I have an ES 7025 that claims long eye relief but they don't provide a spec. This will probably be OK too.
https://www.optcorp.com/explore-scie...-eyepiece.html

The meade HD-60 4.5 claims greater than 17 mm. So that should be enough for me to try it at the high mag range.
https://www.optcorp.com/explore-scie...-eyepiece.html

And the Celestron zoom claims 15 to 18. This is my most used eyepiece.
https://www.optcorp.com/explore-scie...-eyepiece.html

Then I have two plossls at 5 and 2 mm. either I will continue to use them without glasses or they will have to be replaced.

We will see.

[inertia8 (Australia)]

During my loan scope introduction to astronomy, I found the plossl's that come with the scope too tight on eye relief to use with glasses, couldn't get the full fov.

I have an ES82 6.7mm and this is very tight, I need to push the glasses lense closer to my eye and then rest it against the eyecup to see most of the fov, hence I have since bit the bullet and paid the premium for XW's, though I did buy an ES68 24mm and this is perfectly fine for my use with eyeglasses. incidentally when looking up the ER of this (18.4mm) it is now on sale at Agena for 99.99usd.

[AEAJR (Ed)]

That sale is the reason I started this discussion. If I had to replace eyepieces, I wanted to know if these would be suitable. Seems th 6.7 might not and that was one of the ones I was considering.

[AEAJR (Ed)]

Originally Posted by dimithri86

Hi Ed,

What is your prescription?

Mine is -0.5 of sphere which I compensate using the focuser (although other people look through a scope I focused and see it clear as well..so the effect might not be much), and I have -2.5 of astigmatism. I wear my glasses all the time, because otherwise the whole world is blurry, however through a telescope without eyeglasses everything is quite clear.

My wife is an optometrist and I've used her trial lenses to see that would make it even sharper, but it looks to make little if any difference.

Have a go, it might not too bad for you.

Rt is Cyl +1.25 Lft Cyl +.75

[DavidLJ (David)]

I have pretty severe astigmatism and myopia. Some years ago during a visit to my optician I mentioned the problem this gave me when using an eyepiece and she suggested making up a lens to specifically correct for my astigmatism saying that it could be mounted in an old 1 1/4 inch filter housing. As you probably know, the myopia can simply be corrected by using the telescope focusing system. This works well. After screwing the "filter" onto the eyepiece barrel it is simply a matter of rotating the eyepiece in the focuser until the direction of the astigmatism correction matches the direction of the astigmatism defect of the observing eye. Observing when using eyeglasses works too but usually the eye is then too far away from the eyepiece to be able to get the whole fov at once. Using the astigmatism correcting filter overcomes this problem. I don't know if this system works for all eyepieces but it does for the few that I use. Of course it's a bit of a bother having to remove the "filter" when sharing the view with someone else.

[AEAJR (Ed)]

That is a very interesting approach.

[SkyWatch (Dean)]

Originally Posted by AEAJR

That is a very interesting approach.

It is basically the same approach as using the Televue Dioptrx adapters (but probably cheaper!)

With regard to eye-relief, the Long Perng planetary eyepieces have 20mm eye-relief, as do the Orion "edge-on" and Williams "super planetary" (they are all the same, just different branding: but the Long Perng are a lot cheaper), so if you want to replace your plossls they are a good place to start.

I have moderate astigmatism as well: Venus goes from two "Eiffel towers" inverted on each other (hollow in the middle!), with 18 spikes and covering about 1/2 degree naked eye to a little ball when I wear glasses; and all of a sudden there are twice as many stars in the sky as well! However, I find that when the exit pupil is around 2mm or less I really don't need the glasses.

I echo the comment about taking care when you first get the glasses. I didn't run off the road, but I had to be vary careful when using stars as my feet weren't in the same spot as they used to be! It was fine after a few days though.

All the best,

Dean

[Wavytone]

OP,

As a long time wearer of specs (50+ years) and stargazer: For eyepieces,

1.its all about long eye relief. 20mm is what you need; anything less, forget it.

2. take a close look at the what's facing your specs (and your eye). Any metal rings - or edges (even worse) will rub the specs, and may leave a permanent scratch, even with hard coatings.

Best are types that have a rubber ring or eyecup of some sort that can be folded down (leaving room for the specs) but preventing the specs touching anything metallic.

3. Get a neckstrap for your specs so you don't lose them in the dark.

Even a safety pin stuck in your collar and some thread will do at a pinch.

[AEAJR (Ed)]

Wavytone, thanks for the tips.

It is becoming clear that 20 mm is the minimum I need to get if I am getting a new eyepiece that I want to use with glasses.

[DazzaS (Darrell)]

When you have your EP sorted here is a handy tip for cleaning your glasses for some smudge free viewing

Click here to load the video

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[AEAJR (Ed)]

This is what I finally did.

Based on information received here and the advice from the Televue site I figure that I won't be bothered by the astigmitism on eyepieces under 10 mm which is where my short eye relief eye pieces are. Over that I have enough eye relief in my eyepieces that I can keep the glasses on if I wish.
http://televue.com/engine/TV3b_page....54&Tab=_Choose

So I could have stayed with my current eyepieces BUT Explore Scientific has this great sale on the ES 82s. Normally $150 US, on sale for $100, so I decided to replace my 6.4 mm Meade Plossl (2 mm eye relief) with an ES82 6.7 mm eyepiece (14 mm ER). It arrived today.

I have only tried it out in daytime in my 400 mm FL ETX 80. I thought I would do a quick comparison with my 6.4mm Meade Plossl. As expected the FOV difference is huge. And I was pleasantly surprised that the ES 82 eyepiece is smaller than I had expected, which is good. It is smaller than my Meade HD-60 4.5 mm.


I can't use the 6.4 Plossl with my new glasses, at 2 mm eye relief. If I take the glasses off I can see the whole ES 82 FOV. With the glasses on I can't see the whole view but I still see a wider FOV with the glasses on with the ES 82 than I can see with the Plossl with the glasses off, so that is still an improvement if I want to wear the glasses.

It will be nothing but clouds and rain for the next 4 days. I can't wait for a clear sky.