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Best eyeglasses lenses for stargazing (& night driving).

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#26 Sarkikos

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Posted 14 January 2020 - 07:44 AM

I have myopia, presbyopia and astigmatism.  So whatever eyepieces I have for astronomy better be progressive or at least bifocal.  Single focus eyepieces are out of the question.  I'm not switching between far-distance and near-distance pairs of glasses, or using a magnifying glass. 

 

I need to see the night sky clearly without the telescope and also be able to see charts clearly in SkySafari Pro.  I star hop.  I go back and forth quickly and often among sky view, telescope view, finder view, and SkySafari Pro view.  Switching among eyeglasses or a magnifying glass isn't going to cut it. 

 

Mike

I just now glanced back at my post.  I should have written "eyeglasses" not "eyepieces"  in the second sentence.  Dang it!  Too late to edit the post.  But it looks like folks knew what I meant.  

 

Mike


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#27 Morseman

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Posted 22 June 2020 - 02:46 PM

Are there any other reviews of Zeiss i.Scription eyeglasses for observing?  Any cost information?

 

How about the "HD glasses" and "Digital Surfacing" lenses?

 

They do sound promising, but in researching these on the internet, it is so hard to separate technological improvements from marketing hype.

 

Also, I called several so-called "Zeiss Vision Provider" opticians in my area (suburban MD, outside DC) and none of the folks I spoke to on the phone knew what I was talking about or even offered to transfer me to someone who did.  I also emailed Zeiss last week asking who in my area offers these, but so far no reply.

 

--Bob--


Edited by Morseman, 22 June 2020 - 02:46 PM.


#28 Keith NC

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Posted 22 June 2020 - 03:01 PM

Are there any other reviews of Zeiss i.Scription eyeglasses for observing?  Any cost information?

 

How about the "HD glasses" and "Digital Surfacing" lenses?

 

 

 

--Bob--

“HD glasses” is purely a marketing term.  Digital surfacing has been the primary means of generating the curves on the backside of an ophthalmic lens for the last 15 years so very likely any pair of lenses you were to purchase today have likely been produced on a digital generator.

 

Essilor, Hoya, and Shamir also all have good designs for progressive lenses.  Zeiss does not have significant market share in the US but also have good lens designs
 

hope this helps



#29 Heywood

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Posted 22 June 2020 - 03:14 PM

My experience is that glass lenses are the best material optically for eyeglasses, followed by CR39 plastic. Every other material is inferior to one degree or another. That is all there is to it.

I think if you research this question, you will find that I am correct.

Of course, you will find lots of marketing hyping other materials, but that's just marketing, not reality.

Edited by Heywood, 22 June 2020 - 03:17 PM.


#30 Keith NC

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Posted 23 June 2020 - 07:55 AM

My experience is that glass lenses are the best material optically for eyeglasses, followed by CR39 plastic. Every other material is inferior to one degree or another. That is all there is to it.

I think if you research this question, you will find that I am correct.

Of course, you will find lots of marketing hyping other materials, but that's just marketing, not reality.

Absolutely true in terms of abbe value.  If other factors are important (e.g. impact resistance, thickness/weight) you would also consider other lens materials as well



#31 Heywood

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Posted 23 June 2020 - 10:03 AM

Absolutely true in terms of abbe value.  If other factors are important (e.g. impact resistance, thickness/weight) you would also consider other lens materials as well

 

Correct.

 

I found that the weight of the glass lenses is not bad at all as long as I get frames that require small to medium-size lenses.  In other words, the "heavy weight" of glass lenses is overblown.  However, if a person insists on 1980's-style or aviator-style big lenses, then yes, they're going to be heavy. 


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#32 Starman1

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Posted 23 June 2020 - 11:47 AM

Glasses lens size preference depends a lot on the size of the lenses in the eyepiece.

 

I found that with long eye relief ultrawide eyepieces, the eye lenses were so large in diameter, the frames of the glasses were in your field of vision with fashionable lens sizes and shapes.

Aviator-size lenses or even the oversized lenses of the '80s would seem to be better for astronomy with such eyepieces.

I pulled out an old pair I had from the '80s and the larger lenses edges are out of my vision, whereas all more recent glasses, with smaller lenses, definitely have their frames in my field of vision.

 

This will not be a problem with long eye relief eyepieces up to about 65-68°, but is an issue with larger apparent fields on long eye relief eyepieces, like the Morpheus, Docter, APM HiFW, TV Apollo, 31 Nagler,

ES 92s, and probably others that qualify for long eye relief.



#33 Jon Isaacs

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Posted 23 June 2020 - 12:34 PM

Absolutely true in terms of abbe value.  If other factors are important (e.g. impact resistance, thickness/weight) you would also consider other lens materials as well

 

For everyday use, glass lenses shatter so plastic is he way to go..

 

CR39 is brittle but much less so than glass.

 

Jon


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#34 Morseman

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Posted 23 June 2020 - 05:00 PM

Keith, thanks for the reply.  Still have not found a shop that uses the Zeiss technology, and Zeiss U.S. has not replied to my inquiry.

 

--Bob--



#35 Heywood

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Posted 23 June 2020 - 05:15 PM

For everyday use, glass lenses shatter so plastic is he way to go..

 

CR39 is brittle but much less so than glass.

 

Jon

 

I have worn glass and CR39 lenses for 55 years and never had a problem.  It would take a highly unusual and powerful impact to shatter my glass lenses.  Of course, I would never wear them while engaged in a contact sport or other hazardous activity.


Edited by Heywood, 23 June 2020 - 05:16 PM.


#36 Jon Isaacs

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Posted 23 June 2020 - 05:37 PM

I have worn glass and CR39 lenses for 55 years and never had a problem.  It would take a highly unusual and powerful impact to shatter my glass lenses.  Of course, I would never wear them while engaged in a contact sport or other hazardous activity.

I have a few years on you.

 

I used to wear glass lenses. 

 

I learned that lesson the hard way. You never know when something might come flying. Eyeglasses serve as both optics and protection. 

 

And too, glass lenses can shatter if dropped. Plastic lenses scratch so at least you can still wear them.

 

Jon


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#37 25585

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Posted 24 June 2020 - 04:30 AM

I used to have shatterproof toughened glasses, needed for motorcycling, then switched to polycarbonate.

 

Not sure what plastic I have now but its light and good optically.

 

Glass lenses steam up quickly outside and attract dew faster, no heating strip as eyepieces have.



#38 Sarkikos

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Posted 30 June 2020 - 09:06 AM

Soapy water wiped on eyeglasses will keep the dew off.

 

Mike



#39 decep

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Posted 30 June 2020 - 10:58 AM

Soapy water wiped on eyeglasses will keep the dew off.

 

Mike

Interesting anecdote to this.  I watched this video a few months back.  It tests Rain-X against some urban legend options for fog reduction on glass.

 

After Rain-X, [gel] shaving cream was one of the best options to keep fog off glass.

 

https://www.youtube....h?v=8Vj9avZxuwI


Edited by decep, 30 June 2020 - 10:58 AM.

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#40 decep

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Posted 30 June 2020 - 11:23 AM

The old link to the PDF is dead.  I think this is the same PDF:  https://skyandtelesc.../spectacles.pdf


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#41 Sarkikos

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Posted 30 June 2020 - 12:04 PM

The old link to the PDF is dead.  I think this is the same PDF:  https://skyandtelesc.../spectacles.pdf

Yes, it is.

 

Mike



#42 AstroVPK

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Posted 30 June 2020 - 04:31 PM

Just came back from my visit to the optician. I had them do a prescription for Zeiss iScription glasses optimized for infinity focus along with a second pair for daytime use in front of a monitor. Since both eyeglasses will have the same prescription, I'll be able to compare the iScription against regular lenses and report back here. Interestingly, my doctor offered me scleral contact lenses. Since the fitting process takes ~ 3 months and involves several visits to the clinic, I chose not to go down that route thanks to COVID-19, but I'll take him up on it next year.

 

At the end of last year, I had the same clinic (different doctor who's retired now) make me a pair of hybrid contact lenses called duettes. The basic principle is that these contacts offer a rigid gas permeable center surrounded by a soft skirt that rides on your iris. The soft skirt keeps you comfortable while the rigid gas-permeable center gives you sharp, eyeglass like vision. The doctor hoped that I'd have great vision with these hybrid lenses specifically for astronomy. There were two concerns i. my dark adapted eye may have a bigger pupil than the size of the gas permeable center which would lead to aberrations when used in the dark ii. I have some astigmatism that originates on the inside of my eye-lens which these hybrid contacts cannot correct.. After a few months of evaluation, I've come to the conclusion that while these hybrids may work for older eyes, they are probably not ideal for astronomy. It seems that I have a large enough pupil that I get severe aberrations on brighter stars. In particular, I found that Jupiter exhibits a ~ 20 arcsec halo when looked at through the hybrid lenses. To establish that the source of the halo is light coming from the periphery of the lens i.e. where the soft skirt is, I alternated between looking at Jupiter after giving my eyes ten minutes to dark-adapt v/s right after looking at the screen of my cell phone. When I'd look at Jupiter with 10-minute dark-adapted eyes, I'd see the halo. When looking at Jupiter right after looking at my cell phone screen, I would not see the halo at first, but it would start 'growing' and soon (within 1 - 2 minutes) be about as large as when looking with 10 minute dark-adapted eyes. The 'growing' effect was astonishing to watch and easy to see - I repeated this exercise several times to be sure that I wasn't mistaken about what i was finding.

 

In summary:

i. Hybrid contact lenses may work for older eyes with a small pupil, but do not work for eyes that can still open wide.

ii. I will be testing the Zeiss iScription lenses against regular lenses soon (~6 weeks during COVID-19) so expect a comparison.

iii. I will be testing scleral contact lenses next year (assuming we have a COVID-19 vaccine).


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#43 DSOGabe

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Posted Yesterday, 10:57 AM

I've discovered it easier, for me at least, just to take off the glasses to observe. I can't seem to get a good focus with them on. I just plop them onto the eyepiece tray. Still looking for a lanyard to hang them off my neck. 



#44 DSOGabe

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Posted Yesterday, 11:00 AM

I’m in the middle of a multi year project to slowly walk my myopic eyes back to 20/20 (astronomical), and thus am going through about 24 sets of glasses.

 

Can you please share that routine with me? I'd love to chuck the glasses altogether.


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#45 hoof

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Posted Yesterday, 09:35 PM

Can you please share that routine with me? I'd love to chuck the glasses altogether.

:)  If you do it right, you won't chuck the glasses, just end up with glasses for near work to prevent sliding back into Myopia again.

 

Basically, in a nutshell, the eye is both a self-calibrating device, and capable of accommodation both towards you and away from you. 

 

Most of us are familiar with the accommodation that allows seeing closer.  Most people are unaware that you can actually push your vision a little bit further than the "relaxed" state of the eye.

 

The eye is most relaxed at a certain focus distance.  "Normal" vision people have that focus distance far away or infinite.  People like me have their focus distance closer, mine is about 33cm (it used to be 20cm).  I can focus closer than that, and I can focus a bit further than that.  

 

The other part is that the human eye is self-calibrating.  There is simply no way one can encode into a few genes the recipe for accurately calibrated eyes, that stay calibrated as the eyes grow through childhood, and stay calibrated over potentially a century..  Eyes grow, every pair is different, etc, etc etc.  So the eyes "calibrate" over time.  If you spend a ton of time looking close, they will recalibrate so that you naturally see close without trying. We call that "myopia", or nearsightedness.  If you spend a ton of time looking far away, the eye will recalibrate to see farther.  We call that "hyperopia" or farsightedness.

 

The two ways that the eye calibrates are based on where you spend your time looking.  I spent a ton of time as a kid looking at computer screens and books.  Thus my eyes calibrated for that distance.  I then went to an Optometrist, since far stuff was blurry, they gave me glasses to look at far away things.  I stupidly wore those glasses for close up stuff, leading to repeating that calibration cycle over and over again until I couldn't see naturally more than 20cm, or 8".

 

That process works in the other direction.  By pushing your eye's focus further than that the "relaxed" position, the opposite occurs, the eyes recalibrate towards distance vision.  

 

Both processes are very slow, typically 0.75 to 1.25 diopters a year when done to an extreme.

 

So far, after a year of this, I can now drive at dusk with -3.0 diopter glasses and see as well as I did a year ago with my last "prescription" of -5.0 diopters.  It does work.  I estimate that I will no longer need glasses for distance vision in about 2.5 years, at the current rate of improvement.

 

But it takes discipline.  I was disciplined (inadvertently) to get myopic, by constantly looking at stuff up close with my distance glasses for hours each day.  To go the other direction, I spend most of the day at "the edge of blur", or with a prescription that's too weak to let me see clearly without pushing focus.  I also avoid looking closer than my current prescription as much as possible (e.g. I take off my glasses to look at my phone).  But accommodation in the push-out direction maxes out at 0.5D, while near accommodation is 3 to 5D.  Thus I have several sets of glasses that I'll switch between during the day, and have to step them down every 10 weeks or so.  Much more of a hassle than when I was making myself nearsighted!  And certainly more work than getting my eyes zapped by a laser!

 

And the kicker is, once there, the glasses don't go away.  If I don't wear glasses while on a computer or phone when back at 20/20, that makes me pull focus in, which starts the recalibration over again to make me nearsighted.  That's like going on a diet, losing 50lbs, then going back to my old eating habits. Baically a recipe for undoing all that hard work.  The remedy?  Plus glasses for close up work.  Thus the glasses don't go away.

 

So if I'm not going to ditch the glasses, and it takes years, and dozens of pairs of glasses, why bother?  I want to see if it can be done!  Everyone says myopia is a one-way street.  I have experienced the fact that that isn't true.  So I want to be there.  And I'd like to try using glasses only for near stuff for a while! =)  

 

Check in with me in a few years, I'll let you know if I'm successful in getting all the way back!

 

I've already seen another payoff.  My 7 year old started getting a little near-sighted (about 0.25-0.5 diopters).  I got her glasses.  But not regular near-sighted glasses, I got her reading glasses!  She wears them for all her close-up work (never for far viewing). Within a few months, she now she sees like an eagle, and will likely never develop myopia in her life.  Knowing how the eye calibrates and how to manage that has made it so my kids will never have to live near-sighted like I do. And that is even better than me seeing 20/20 again.


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