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STOP! Take off your GLASSES if you own ED Binoculars!!! (1 Viewer)

dozercsx

Active member
Greetings,
I just discovered a series of articles around a super important fact if you are an eyeglass wearer AND a Binocular user:

Polycarbonate lenses are the WORST optical material when it comes to Chromatic Aberration: Here's one comment from the optics article I am posting:

"Abbe values of eyeglass lens materials range from a high of 59 (crown glass) to a low of 30 (polycarbonate). The lower the Abbe number, the more likely the lens material is to cause chromatic aberration."

Here's another quote from the Sky and Telescope article on eyeglasses:
"Refrain from the use of polycarbonate lenses" as they "exhibit the worst chromatic aberration of any ophthalmic lens material available."

So, in effect, if you have polycarbonate eyeglass lenses AND you own (expensive!) ED glass binoculars, those polycarbonate lenses are neutralizing the value of your ED glass!

I'd like some of you to test this - TRY your ED glass binoculars with and without your spectacles - and check back if (1) yours are polycarbonate, and (2) you see a difference, in particular, with the colors that are transmitted through the binoculars! (from my review of the Orion Otter EDs, it's clear that the most dramatic benefits of ED glass are preservation of color, so the difference would probably be pretty big)

Here are the articles:

https://skyandtelescope.org/wp-content/uploads/spectacles.pdf
https://www.allaboutvision.com/lenses/how-to-choose.htm

Enjoy!
 

A2GG

Beth
Supporter
United States
I have polycarbonate eyeglass lenses. When I first got them years ago I did notice some CA initially, but later did not notice it anymore. I guess my eyes adjusted. I don't see it in my latest lenses.

I can still tell the different levels of CA between binoculars. I see a little occasionally under the right conditions with my Swarovski CL 8x30 (original version). However, when I owned a Zeiss FL 8x32 I could not see any CA except on the extreme edges at times and it was very minor. So, despite having eyeglasses with poly lenses I still experienced a mostly clean image free of CA using the FL as others do.
When I had the Ultravid HD Plus 7x42 I saw only minor CA off axis. Maybe my eyes have adjusted to the polycarbonate lenses. I don't think they cancel out good ED binoculars. I can still tell which binoculars control CA better than others if I look for it.
 

A2GG

Beth
Supporter
United States
Also, from what I've read online in the past about Polycarbonate lenses, CA should not be present right in the center if the lenses are good.
 

AlanFrench

Well-known member
I changed to binoculars with good eye relief because birding without glasses, or birding and taking glasses on and off, is just a ridiculously annoying exercise. Have never noticed CA in my glasses or binoculars to be an issue.

Clear skies, Alan
 

Alexis Powell

Natural history enthusiast
United States
Polycarbonate is indeed terrible for CA, but wearing them doesn't neutralize ED bins, esp. since you will be using them mostly on axis. For viewers w/such glasses and lots of astigmatism, they will still be better off with glasses on.

That said, I despise polycarbonate glasses for their horrible CA in regular use. Everything off-axis is blurry due to extreme CA. For folks like me who move their eyes around, constantly looking about, they are intolerable.

Regular CR39 is excellent. I'm told Trivex is in-between in performance. I get all my glasses in glass.

--AP
 

Kevin Conville

yardbirder
Garden variety std. index Polycarbonate lenses are the worst, material wise, with
high index lenses having an even lower Abbe index.

Trivex and crown glass are the best optically but Trivex is uncommon and glass only works well (weight wise) for smaller frames and less corrective prescriptions.

I have a strong prescription so I'm flat out of luck for high quality glasses. Several years ago I wanted to ditch contacts to primarily wear glasses and found out the visual facts of life. I still wear contacts, for best vision.

Plastic lenses also don't fare well (from abrasion) by eyecups either, especially dusty ones. If I had a much milder prescription I'd wear Zeiss prescription glass(es).
 
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WJC

Well-known member
"Abbe values of eyeglass lens materials range from a high of 59 (crown glass) to a low of 30 (polycarbonate). The lower the Abbe number, the more likely the lens material is to cause chromatic aberration."

Here's another quote from the Sky and Telescope article on eyeglasses:
"Refrain from the use of polycarbonate lenses" as they "exhibit the worst chromatic aberration of any ophthalmic lens material available."

So, in effect, if you have polycarbonate eyeglass lenses AND you own (expensive!) ED glass binoculars, those polycarbonate lenses are neutralizing the value of your ED glass!

I'd like some of you to test this - TRY your ED glass binoculars with and without your spectacles - and check back if (1) yours are polycarbonate, and (2) you see a difference, in particular, with the colors that are transmitted through the binoculars! (from my review of the Orion Otter EDs, it's clear that the most dramatic benefits of ED glass are preservation of color, so the difference would probably be pretty big)

Here are the articles:

https://skyandtelescope.org/wp-content/uploads/spectacles.pdf
https://www.allaboutvision.com/lenses/how-to-choose.htm

Enjoy!

200820

I think it’s a shame the ophthalmic dispensers don’t know more about REAL optics. I have been told so many times that acrylics and polycarbonates are both lighter than glass and more scratch resistant. The first part of that is true—especially if you have a thick Rx. However, while the latter doesn’t shatter like glass does, I think you will find it scratches easier!

In telescope making, we are told that, “Pyrex has a thermal coefficient that changes 1/3rd as much as plate glass.” And that is so very true. However, there are FOUR more parts to that equation that are consistently overlooked.

1) That same coefficient allows the plate glass mirror to cool and be ready for testing or observing THREE TIMES as fast.
2) Plate glass takes a smoother polish than does Pyrex.
3) You can grind and polish plate glass much faster than Pyrex.
4) Some of the word’s most prominent telescopes feature plate as the crown element.

No, I don’t pull the heads off baby chicks at Easter. But I do believe that some bubbles need to be popped. :cat:

Bill
 

Kammerdiner

Well-known member
Yes, the first pair of polycarbonate glasses I got were a CA disaster. Never had them since. I specifically tell them I don't want poly lenses.

I do wonder how anyone can use them. Guess I'm picky, lol.
 

Binastro

Well-known member
I notice a distinct colour shift with polycarbonate glasses compared to no glasses.

I don't use glasses with scopes or binoculars.

Regards,
B.
 

A2GG

Beth
Supporter
United States
I notice a distinct colour shift with polycarbonate glasses compared to no glasses.

I don't use glasses with scopes or binoculars.

Regards,
B.

I'm not suggesting you're wrong , but I just don't see a color shift at all when I put my glasses on. I would have noticed this effect by now after all these years. I just went out to specifically to check for this and I don't see it. I also didn't see any CA but next time it's cloudy with white or gray sky I'll take a better look. Maybe it's because my eyes just look through the center and not the periphery of the lenses.

I guess I'm weird ... I always ask for polycarbonate with new prescriptions.
I like the protective material and built in UV protection. I don't see any scratches on my lenses but I take good care of my glasses and binos too.
I have a friend who always sits on her glasses and drops them. The frames are all bent.
 
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Binastro

Well-known member
Hi GG,

I specifically notice the shift on a candle flame.
I would have to light a candle to see what the shift is, maybe bluer.
It is quite striking to me.

However, I rarely light candles because of the fire risk.

Regards,
B.
 

Chosun Juan

Given to Fly
Australia - Aboriginal
I'm not suggesting you're wrong , but I just don't see a color shift at all when I put my glasses on. I would have noticed this effect by now after all these years. I just went out to specifically to check for this and I don't see it. I also didn't see any CA but next time it's cloudy with white or gray sky I'll take a better look. Maybe it's because my eyes just look through the center and not the periphery of the lenses.

I guess I'm weird ... I always ask for polycarbonate with new prescriptions.
I like the protective material and built in UV protection. I don't see any scratches on my lenses but I take good care of my glasses and binos too.
I have a friend who always sits on her glasses and drops them. The frames are all bent.

GiGi - I don't see any real colour shifts either. Like you, I have specifically checked in the past when I thought that individual binocular tube had different cool/warm colour casts. Turned out it was my eyes ! The one warm/one cool view turned out to be the same with or without glasses during late afternoon viewing when this David Bowie phenomena kicks in.

I've never really paid attention to the specs of my specs !
I just say use whatever gives me the best result with the "Transitions" photochromic treatment.

I can tell you that my lenses are a fair myopic prescription, and robust - I have put them through a couple of impromptu 'tests' - from treading on an upturned rake and whacking myself in the face/glasses cartoon style (that left an unnoticeable 4mm crack in one lens) , to falling off a 10ft ladder and landing on top of the Fallen aluminium ladder with my hip/shoulder/head ! That resulted in a bruised hip, broken & dislocated shoulder, twisted glasses frame, a black eye, and a pirate-like Z shaped cut right next to my eye - which the doctors glued back together ! The glasses lenses survived completely intact - I was super lucky not to lose an eye. The ladder wasn't so lucky - there were big shoulder/head sized dents in it !

I do notice that lining up bins/eyes/target is pretty critical. Only the alpha bins are really easy in this regard (my Zen is pretty good, but ER is a bit marginal). Unless the bins are top notch (low CA, SA, etc) I do find an objectionable amount of CA when looking off axis. The best performing bins for me in this regard are the Swarovski SV's with their generous randpupille design. The SF and HT are also good due to their low CA performance. This is also a key reason why the Zen's work well for me - their CA handling is excellent in the centre third of the view and only mildly progressively deteriorating outside of that.

Testing with and without glasses, it is clear that the glasses lenses are contributing their own CA notably off axis. At least I've still got eyeballs. :eek!:








Chosun :gh:
 

Chosun Juan

Given to Fly
Australia - Aboriginal
I changed to binoculars with good eye relief because birding without glasses, or birding and taking glasses on and off, is just a ridiculously annoying exercise. Have never noticed CA in my glasses or binoculars to be an issue.

Clear skies, Alan

I'm with you on that !
I tried the on-/-off routine for a while and it was very annoying.
I was also blind as a bat (short-sighted), and had to try and point by sound on anything less than an Eagle-sized bird ! :eek!: :-O

The only way that works for me is glasses on full time and bins to suit.








Chosun :gh:
 

A2GG

Beth
Supporter
United States
Hi GG,

I specifically notice the shift on a candle flame.
I would have to light a candle to see what the shift is, maybe bluer.
It is quite striking to me.

However, I rarely light candles because of the fire risk.

Regards,
B.

Wow...I just lit a candle and tried it and I noticed the blue of the flame does indeed look a little more saturated blue. I lifted the glasses up and down a bunch of times and didn't notice it right away but after several times I can see the blue pop out a bit more. It's pretty subtle but after a while it became noticeable; a slight difference.
 

A2GG

Beth
Supporter
United States
CJ (post 12),

I remember you telling me about falling from the ladder and how much
you had to go through to get better and the lingering issues.
You definitely made the right choice with the poly lenses !
Glad your eyes were safe.
 

A2GG

Beth
Supporter
United States
Wow...I just lit a candle and tried it and I noticed the blue of the flame does indeed look a little more saturated blue. I lifted the glasses up and down a bunch of times and didn't notice it right away but after several times I can see the blue pop out a bit more. It's pretty subtle but after a while it became noticeable; a slight difference.

But now I think it's really not a color bias but just colors and contrast appearing bolder due to the eyeglasses correcting my vision. I'm looking at the tv and around the living room with glasses on and off and colors are a tiny bit more saturated with glasses.
But I certainly can't argue with anyone who sees what they see with their own eyes through their pair of glasses.
 

WJC

Well-known member
I guess I'm weird ... I always ask for polycarbonate with new prescriptions.

I like the protective material and built in UV protection. I don't see any scratches on my lenses but I take good care of my glasses and binos too.
I have a friend who always sits on her glasses and drops them. The frames are all bent.

“... and built-in UV protection.”

I can’t remember what specifics Holger told me about this. So, I will resort to the approximation I used before I knew him:

Uncoated glass stops UV at about 50% per millimeter. It’s not that the ophthalmic practitioners are dishonest, it’s just they’re not taught to get into some realities. :cat:

WJC
 

A2GG

Beth
Supporter
United States
“... and built-in UV protection.”

I can’t remember what specifics Holger told me about this. So, I will resort to the approximation I used before I knew him:

Uncoated glass stops UV at about 50% per millimeter. It’s not that the ophthalmic practitioners are dishonest, it’s just they’re not taught to get into some realities. :cat:

WJC

Did some digging. Pretty much all vision sites I visited state 100% UV protection with Polycarbonate lenses, but I found this site that states it naturally filters out some range of UV, but not all of it:

https://www.hexarmor.com/posts/not-all-uv-lenses-are-created-equal

Here's the blurb you don't have to read through the whole thing:

The good news is that polycarbonate, which is what most safety eyewear lenses are made of, will help to naturally filter out some of this UV light. Polycarbonate only filters up to 380nm, leaving a 20nm range unprotected.

According to The Vision Council, the majority of harmful UV radiation comes through at a higher frequency, and the range of 380-400nm lets through as much as 40% of the most harmful UV rays. Not protecting yourself from the additional 20nm of UV light can lead to Photokeratitis (also known as “sunburn of the eye”) in the short term, and cataracts or macular degeneration in the long term.
 
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WJC

Well-known member
Did some digging. Pretty much all vision sites I visited state 100% UV protection with Polycarbonate lenses, but I found this site that states it naturally filters out some range of UV, but not all of it:

https://www.hexarmor.com/posts/not-all-uv-lenses-are-created-equal

Here's the blurb you don't have to read through the whole thing:

The good news is that polycarbonate, which is what most safety eyewear lenses are made of, will help to naturally filter out some of this UV light. Polycarbonate only filters up to 380nm, leaving a 20nm range unprotected.

According to The Vision Council, the majority of harmful UV radiation comes through at a higher frequency, and the range of 380-400nm lets through as much as 40% of the most harmful UV rays. Not protecting yourself from the additional 20nm of UV light can lead to Photokeratitis (also known as “sunburn of the eye”) in the short term, and cataracts or macular degeneration in the long term.


Hi GG,

Did you know you were a freak of nature and are setting a good example? You did some digging of your own, which will cause me to do some digging of MY own; I hate it when that happens. Next week, I will reach out to a friend at the University of Arizona’s College of Optical Sciences who has Ph.D.s in both precision and ophthalmic optics. In the meantime, consider that your findings did not specify the THICKNESS of the refractive material. Infrared plows on through. But UV seems to be dramatically attenuated by increased thicknesses of the filtering material. Thus, one thickness does not answer the all-important question. :cat:

Bill
 

A2GG

Beth
Supporter
United States
Hi GG,

Did you know you were a freak of nature and are setting a good example? You did some digging of your own, which will cause me to do some digging of MY own; I hate it when that happens. Next week, I will reach out to a friend at the University of Arizona’s College of Optical Sciences who has Ph.D.s in both precision and ophthalmic optics. In the meantime, consider that your findings did not specify the THICKNESS of the refractive material. Infrared plows on through. But UV seems to be dramatically attenuated by increased thicknesses of the filtering material. Thus, one thickness does not answer the all-important question. :cat:

Bill

Thanks Bill. Yep, I do know I'm weird o:) I like to try and get to the truth of things. Let us know what you find out from your friend :t:
 
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