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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Eyeglasses, AR coatings, antireflective. (1 Viewer)

The first time I got into trouble on BF, it was because I yanked the chain of a particular new and inexperienced member who immediately took it upon himself to “verify” so many of the things I said, sometimes leading members down a blind alley. So, I hope no one thinks I’m trying to pull that on Looksharp65. His words need no verification. I only speak to echo. (the caps are mine)

“The residual reflection is chosen TO SATISFY THE CUSTOMER'S NEED to see they really paid for something visible.”

This is like the original* (1933) Windex having a couple of drops of Aquatint to show homemakers they were buying something more than water.

“... common-sense tells that with a 99% transmission, a residual reflection of a very narrow wavelength span can't possibly affect the perceived colour balance THROUGH the lens.”

Also, AR coatings don’t have a color; they reflect a wavelength that is intuitively seen as color. Thus, the art of stacking BBs continues to grow.

Bill

* PS Today’s Windex formula specified as the "original" ... isn’t.
 
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Here's a little online colour generator that some might find interesting.
http://www.csfieldguide.org.nz/en/interactives/rgb-mixer/index.html

Try first setting all the red, green and blue values to 200. You find it much easier to do if you zoom in. It should produce a completely neutral mid grey. Start with the green, and move the slider in one direction one unit at a time, and make a note of when you can see a difference in colour. Then try the other direction. Try repeating it for red and blue.

David
 
typo said:
Lars, Bill,

You might want to check the reflectivity plot from this Zeiss website. Two lens surfaces will double the percentages and viewing at any angle from the perpendicular will increase the reflectance further. There will be a discernable difference in transmitted colour. Who would notice it is another matter.

David

P.S. Oops, forgot the link.
https://www.zeiss.co.uk/vision-care/eye-care-professionals/products/coatings/duravision-silver.html
Click to expand...

Hi, David:

I think a large percentage would notice; whether or not they would care is another matter. Also, my story of the anti-freeze spill on the freeway illustrates the idea of the appearance changing with the angle of incidence and reflection. And then there is consideration of the impulses sensors send to the brain. How could one person say with certainty that the spill was GREEN and another person standing beside him say with certainty the spill was YELLOW? Many people want to live in a world of absolutes, but that world doesn’t exist. Who draws the line that separates yellow from green?

My comment was much simpler than angles and thicknesses; it was just that AR coatings have no “color” and that they just reflect the wavelengths we perceive as color. Life has so many wonderful truths to teach us, at least those who pay attention.

Finally, you forgot the link? Welcome to my world! :cat:

Bill
 
Bill,

What is colour if not the product of transmission, absorption and reflection? Of course it's a figment of the imagination. But then some have more vivid imaginations than others. ;)


David
 
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typo said:
Bill,

What is colour if not the product of transmission, absorption and reflection? Of course it's a figment of the imagination. But then some have more vivid imaginations than others. ;)


David
Click to expand...

Were it not so, so many of us would need to have our cranks turned by frequenting forms about basket weaving, fart painting, BB stacking, rainbow assembling, or learning to needlepoint with 5-inch Navy hawser. :cat:

Bill
 
Thanks John. I'd seen the pages, but not scrolled down as far as the tables. Interesting info. Nothing in either glass or plastic in the ED range, yet the brain has no trouble sorting out the CA. Remarkable stuff.

David
 
perterra said:
You know the old saying about assuming. In this case, your assumption is wrong. I have been wearing progressives for 20 years, I tolerate them better than looking over or under the lines. I actually have a hard time imagining someone would have that hard of a time adjusting to a pair of progressives with the right lens design...
Click to expand...

Ha! Well, I'm glad to see someone defend progressives. Based on everything I've heard about them though, I still can't believe that their _overwhelming_ popularity (at least where I am) is due to superior functionality for most people. That said, and aside, my prescription is quite stable (so all of my old glasses still work, and I use them) and I don't really need bifocals/progressives, but I have an annual prescription benefit and have been using it these past few years to test different types of glasses so I can find what works for me before I really do need something more than simple lenses. Maybe I'll give progressives a go this time around. What advice do you have when it comes to ensuring that I get "the right lens design?"

--AP
 
Alexis Powell said:
Ha! Well, I'm glad to see someone defend progressives. Based on everything I've heard about them though, I still can't believe that their _overwhelming_ popularity (at least where I am) is due to superior functionality for most people. That said, and aside, my prescription is quite stable (so all of my old glasses still work, and I use them) and I don't really need bifocals/progressives, but I have an annual prescription benefit and have been using it these past few years to test different types of glasses so I can find what works for me before I really do need something more than simple lenses. Maybe I'll give progressives a go this time around. What advice do you have when it comes to ensuring that I get "the right lens design?"

--AP
Click to expand...

Find an optometrist who is very accommodating and do a bunch of research. Having said that for me they are a no brainer (I would be in trifocals) there are a lot of different designs, and the wrong one (like binoculars, every-bodies accommodation is a little different), well the wrong design is almost unusable. I tried several Zeiss designs and couldnt adjust. Have had pretty good luck with varilux, Hoya freeform and Nikon (wish I could remember which). My only advice is go for high index as you can and make sure the design works for you.

If I wore a single vision, I probably would not worry about progressives, bi-focal depending on prescrip, yes, and for sure tri focal.

Mine started at about 45 years old, and my fishing glasses were glass, then they could not polarize plastics, so glass it was.

I have 4 pair that I rotate around depending on where I will be, but if you can get by with glass, it's no big deal, but when that prescrip starts going up, so does weight.
 
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Why one design works for one person and not another is something that my optometrist can't explain. The only clue I have is that the discontinued Essilor design I liked was apparently much more successful with long sighted than short sighted users. Unfortunately that kind of info takes time to accumulate and wouldn't be available for the latest designs.

David
 
typo said:
Why one design works for one person and not another is something that my optometrist can't explain. The only clue I have is that the discontinued Essilor design I liked was apparently much more successful with long sighted than short sighted users. Unfortunately that kind of info takes time to accumulate and wouldn't be available for the latest designs.

David
Click to expand...

Some people superimpose looks, feel, weight, poorly thought out reviews, and other considerations over the top of actual optical and mechanical performance and see problems where there are none. In a rational world, OPINION can never take the place of PHYSICS. However, in the retail world, it is opinion—not physics—that makes the cash register ring. :cat:

“You can run but you can’t hide.”—Paul Harvey

Bill
 
WJC said:
Some people superimpose looks, feel, weight, poorly thought out reviews, and other considerations over the top of actual optical and mechanical performance and see problems where there are none. In a rational world, OPINION can never take the place of PHYSICS. However, in the retail world, it is opinion—not physics—that makes the cash register ring. :cat:

“You can run but you can’t hide.”—Paul Harvey

Bill
Click to expand...

In my case zeiss progressives gave me a splitting headache. Tried remaking with the same result. Switching to crizals at the time solves the problem. My optometrist said it was the design of the magnified area
 
Amen!

Binastro said:
Just had an amazing visual experience.
Went out taking the £6 Readyspex G-61 window shopping glasses +2.25 dioptres.
These are way wrong prescription for me now, as I have probably had the glasses for 15 years, maybe more.
Not sure if glass or plastic, but uncoated. I can't see any colour change with the glasses.

Getting round the corner, people were blurred, so I held the specs 5 inches in front of my eyes.
I saw amazing 3D from 10 yards to 150 yards. The people, perhaps 10 or more, at different distances stood out like sharp 3D beacons. Also they were more or less in focus.
This was really quite spectacular.
The magnification compared with unaided eyes was about 1.7x as I repeatedly lifted the glasses up and down.
This visual delight was something quite unexpected.

Today 23C instead of the normal 32C for the last two months. 4/8 cumulus cloud base 5,000ft. wind 240 degrees 11 knots, visibility 40km 23C dewpoint 8C 1012 hPa.

Yesterday as I stood in the sunshine a very cheerful lady walked past. 'Enjoying the sunshine'. Yes, I said.
'Paradise' she exclaimed. I nodded, even though I thought that the last two months have been more like hell without the teabreaks.
Our houses are designed to retain heat, not get rid of it.
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Amen, brother Binastro! ; )) Thanks for the laugh, and sharing the miserey of what I've felt the last couple of months too! I am so ready for the cooler weather, as now I am about ready to bust from the heat and humidity!

I agree-the buildings we live in concentrate the heat, and give it back again at night-without air conditoning, I would just be wilted lettuce in the Summer months! This comes at a pretty steep cost though, so no new binoculars for me!!!
 
Alexis Powell said:
...I have an annual prescription benefit and have been using it these past few years to test different types of glasses so I can find what works for me before I really do need something more than simple lenses. Maybe I'll give progressives a go this time around. What advice do you have when it comes to ensuring that I get "the right lens design?"

--AP
Click to expand...

Well, having had my annual eye exam (an ordeal for my eye doctor, I'm sure, but he handles my idiosyncrasies with patience and sometimes interest), I've looked into progressives a bit more. My eye doctor is sure that I would hate progressives because all designs have large areas outside the central vertical axis that yield a distorted and potentially unsharp view. Given how much I like to move my eyes rather than my head, he thinks I would be bothered, just as I am by binoculars that do not work well for off-axis viewing due to astigmatism, lots of field curvature, or other optical flaws/limitations. I think that the looking-around-the-view versus the center-the-target-in-the-sights styles of binocular use/viewing are quite important for explaining why some users (like me) appreciate designs like the Swarovski EL SV so much, whereas other users see no need for such extreme off-axis correction.

This thinking leads me to wonder whether those who get along well with progressive glasses fall into the camp that keep their vision directed down the center axis of their bins and perhaps do not care so much for flat-field binoculars, and vice versa.

--AP
 
Alexis Powell said:
Well, having had my annual eye exam (an ordeal for my eye doctor, I'm sure, but he handles my idiosyncrasies with patience and sometimes interest), I've looked into progressives a bit more. My eye doctor is sure that I would hate progressives because all designs have large areas outside the central vertical axis that yield a distorted and potentially unsharp view. Given how much I like to move my eyes rather than my head, he thinks I would be bothered, just as I am by binoculars that do not work well for off-axis viewing due to astigmatism, lots of field curvature, or other optical flaws/limitations. I think that the looking-around-the-view versus the center-the-target-in-the-sights styles of binocular use/viewing are quite important for explaining why some users (like me) appreciate designs like the Swarovski EL SV so much, whereas other users see no need for such extreme off-axis correction.

This thinking leads me to wonder whether those who get along well with progressive glasses fall into the camp that keep their vision directed down the center axis of their bins and perhaps do not care so much for flat-field binoculars, and vice versa.

--AP
Click to expand...
I think there is a lot of truth in that. I had no problems with my first pair of varifocals, took to them within minutes, and I'm not particularly bothered by off axis distortions in binos, I move my head rather than my eyes to scan a view. Mind you, I have relatively narrow field binoculars...
 
Alexis Powell said:
This thinking leads me to wonder whether those who get along well with progressive glasses fall into the camp that keep their vision directed down the center axis of their bins and perhaps do not care so much for flat-field binoculars, and vice versa.

--AP
Click to expand...

Good point Alexis, I have worn vari-focals for years and they work well for me. I also centre the subject in my binos although I am aware of objects at the field edge due to my peripheral vision. Screwing my eyes around to look at the field edge is very uncomfortable for me and produces all kinds of optical weirdness.

Lee
 
Alexis Powell said:
Well, having had my annual eye exam (an ordeal for my eye doctor, I'm sure, but he handles my idiosyncrasies with patience and sometimes interest), I've looked into progressives a bit more. My eye doctor is sure that I would hate progressives because all designs have large areas outside the central vertical axis that yield a distorted and potentially unsharp view. Given how much I like to move my eyes rather than my head, he thinks I would be bothered, just as I am by binoculars that do not work well for off-axis viewing due to astigmatism, lots of field curvature, or other optical flaws/limitations. I think that the looking-around-the-view versus the center-the-target-in-the-sights styles of binocular use/viewing are quite important for explaining why some users (like me) appreciate designs like the Swarovski EL SV so much, whereas other users see no need for such extreme off-axis correction.

This thinking leads me to wonder whether those who get along well with progressive glasses fall into the camp that keep their vision directed down the center axis of their bins and perhaps do not care so much for flat-field binoculars, and vice versa.

--AP
Click to expand...

Alexis

You ask some good questions as usual and this got me pondering a bit.

First off, there are different designs of vari-focal lenses available, some with a wider 'optical corridor' than others. And when looking through binos you only want to be able to roam around the exit pupil. So for an 8x42 you only need the corridor to allow roaming 2.1mm to either side and you can look at the entire field edge to edge.

I chose vari-focals because they give me a bit of help for reading, computer screen/car dashboard and far distance all in one, and although I can see adequately without spectacles I would no more go birding without them than I would go out without binos. But if you wouldn't benefit from vari-focals at the closer distances I list then they are probably an unnecessary complication.

Lee
 
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Troubador said:
Alexis

You ask some good questions as usual and this got me pondering a bit.

First off, there are different designs of vari-focal lenses available, some with a wider 'optical corridor' than others. And when looking though binos you only want to be able to roam around the exit pupil. So for an 8x42 you only need the corridor to allow roaming 2.1mm to either side and you can look at the entire field edge to edge.

I chose vari-focals because they give me a bit of help for reading, computer screen/car dashboard and far distance all in one, and although I can see adequately without spectacles I would no more go birding without them than I would go out without binos. But if you wouldn't benefit from vari-focals at the closer distances I list then they are probably an unnecessary complication.

Lee
Click to expand...

It is the "view of the dashboard AND out of the windscreen" reason that I wear varifocals. I would happily use my binos without glasses but when I sit the specs on top of my head they tend to fall off! So i normally am a spectacles plus binoculars man.
 
Troubador said:
Alexis

You ask some good questions as usual and this got me pondering a bit.

First off, there are different designs of vari-focal lenses available, some with a wider 'optical corridor' than others. And when looking through binos you only want to be able to roam around the exit pupil. So for an 8x42 you only need the corridor to allow roaming 2.1mm to either side and you can look at the entire field edge to edge.

I chose vari-focals because they give me a bit of help for reading, computer screen/car dashboard and far distance all in one, and although I can see adequately without spectacles I would no more go birding without them than I would go out without binos. But if you wouldn't benefit from vari-focals at the closer distances I list then they are probably an unnecessary complication.

Lee
Click to expand...

Thanks Lee, for those thoughts. The idea that only a 4.2 mm diameter circle is needed to roam the FOV is intriguing because it suggests that vari-focals might not hinder off-axis viewing through bins, even if they do reduce the quality of off-axis viewing without bins. I had thought the same about regular bifocals, but in practice, I've found that regular bifocals can, and in practice _do_ interfere with my off-axis viewing through binoculars, even when the bottom lens is set lower than usual. I can see the line in the lower 5th of the field. So between my off-axis viewing and perhaps also how I hold the bins to my glasses when looking in different directions, I use more of my eyeglasses lenses than a 4.2 mm diameter circular area.

Some of my friends, with less accommodation than I have, do not yet use bifocals, but I've been experimenting with and now regularly using them because I like to look at things very closely, similar to how I could as a child. I have bifocals with the supplementary lenses set lower than usual, and with a less negative diopter than usual (I am nearsighted), so that I can look at objects held 15 cm from the end of my nose in perfect focus. Of course I could do better than that when I was younger, but this is a compromise with less extreme close viewing--I have enough accommodation that I can also use the inset lenses to focus sharply on objects held just inside an arm's length, but at that point I can see just as well with the upper part of the eyeglasses lens.

I've become interested in the possibility of an extreme varifocal prescription to allow vision from super-close to infinity, or to allow, once I lose more of my accommodation, the same kind of viewing I accomplish now with bifocals.

--AP
 
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