Join for FREE
It only takes a minute!
Magnifying the passion for nature. Zeiss Victory Harpia 95. New!

Welcome to BirdForum.
BirdForum is the net's largest birding community, dedicated to wild birds and birding, and is absolutely FREE! You are most welcome to register for an account, which allows you to take part in lively discussions in the forum, post your pictures in the gallery and more.

Eyeglasses, AR coatings, antireflective.

Reply
 
Thread Tools Rate Thread
Old Wednesday 8th August 2018, 02:34   #1
NDhunter
Registered User
 
NDhunter's Avatar

 
Join Date: Mar 2009
Location: ND
Posts: 3,786
Eyeglasses, AR coatings, antireflective.

I am wondering how these newer optional coatings affect viewing with binoculars.

I don't wear eyeglasses, except for readers, I have noticed you can tell
when someone is wearing these, with the reflection off of the lens.

I suspect this also affects binocular viewing, and so also must affect color and brightness.

Does anyone know more about this ?

Jerry
NDhunter is offline  
Reply With Quote
Old Wednesday 8th August 2018, 04:20   #2
Bill Atwood
Registered User
BF Supporter 2018

 
Join Date: Feb 2004
Location: Central Illinois
Posts: 827
I need to wear glasses due to severe myopia and dry eyes (forced to ditch contacts). Never did any sort of serious examination of the effect of coatings since I had no options and it would be a waste of time. Don't notice much difference in the image during field use because of coatings. HOWEVER...sidelight and reduced FOV due to the eyes being forced away from the eyepiece is a major detriment. Also, with age and associated presbyopia I'm using progressive lenses which really increase the need for proper eye placement. I absolutely hate needing glasses while birding and would joyfully incinerate a village of small children in order to be able to wear contacts again. As much as I like to try the newest or different version of the alpha bins I think the biggest improvement for my viewing experience would be having the ability to use mid-level or even cheap bins without eyeglasses.

I usually remove my glasses when using a spotting scope. It makes a significant difference in perceived sharpness especially at higher magnifications. I believe this is again due to the progressive lenses. They never seem as crisp as single vision lenses and increase the need for proper eye placement. Many non-birders I know that have tried progressives can't get used to softer image and reluctantly switch to bifocals.

On a positive note, if you absolutely are required to use eyeglasses the AR coatings are a vast improvement (over no AR) for normal use.

Last edited by Bill Atwood : Wednesday 8th August 2018 at 04:25.
Bill Atwood is offline  
Reply With Quote

BF Supporter 2010 2011 2012 2013 2014 2015 2016 2017 2018 Support BirdForum With A Donation

Old Wednesday 8th August 2018, 06:09   #3
Boogieshrew
Registered User

 
Join Date: Feb 2011
Location: UK
Posts: 410
Hi Bill,
I need to wear glasses all the time I am awake. Like you, I don’t like using progressive lenses with bins and scope for the same reasons as you.

So I have a pair of single vision glasses for birding. Much better with optics. The only downside that I live with is difficulty reading maps and books.

Birding aside, it’s such a pleasure to be able to look around by moving my eyes rather than my neck when wearing single vision glasses.

As for coatings, I don’t know what effect they have but I look forward to finding out by following this thread. Good question.

BS
Boogieshrew is offline  
Reply With Quote
Old Wednesday 8th August 2018, 12:32   #4
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 3,855
I have 5 different glasses for different distances plus one cheap uncoated glasses where I use my different eye prescription to increase my depth of field for window shopping.

However, I don't wear glasses with binoculars, except for the 5x10T Zeiss monocular which has such enormous eye relief that I hold it touching my distance glasses for stability.

The 5 different glasses are all simple plastic multicoated single vision.

However, looking at a candle flame, using glasses or not using glasses, there is a big difference in colour. The glasses changing the flame from yellowish to bluish.
I don't know if this is due to coatings, but may well be due to the plastic itself, or the material and coatings combined.

For astronomy colour shade hardly matters, but bird watchers seem to see very subtle colour shades.

My friend's current superb images of Mars using different colour channels and combined white light show large difference in detail seen through the current dust storms.
The infra red image shows much more detail than the other colours.
Binastro is offline  
Reply With Quote
Old Wednesday 8th August 2018, 13:37   #5
Binastro
Registered User

 
Join Date: Aug 2012
Location: S.England
Posts: 3,855
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.
Binastro is offline  
Reply With Quote
Old Wednesday 8th August 2018, 15:31   #6
pbjosh
Registered User

 
Join Date: Apr 2013
Location: Buenos Aires
Posts: 627
I wear standard single vision glasses. I typically have no problems with coatings or glare or reflections, though I imagine it helps that I always wear a curved-brim ball cap and pull it down reasonably low to help block stray light. Aside from needing sufficient eye-relief, I have no complaints or issues using bins with glasses, it's totally natural to me.

I do have one odd interaction of coatings with my polarized prescription sunglasses (Maui Jim brand). I love the sunglasses as they are wraparound so they block more light and wind and just fit better. They work fine with my other binoculars but with my Zeiss SF 8x42 there is something odd going on in the way of polarization or coating interaction and, particularly when looking at water, but sometimes visible against large leafed / lush foliage, I get weird bronzy brown and purple colors and a not very pleasant viewing experience. It's generally not a problem in a desert or field or open on land environment but it's a no go on pelagics...
pbjosh is offline  
Reply With Quote
Old Wednesday 8th August 2018, 15:59   #7
Pileatus
Registered User

 
Join Date: May 2004
Location: USA
Posts: 2,491
Quote:
Originally Posted by pbjosh View Post
I wear standard single vision glasses. I typically have no problems with coatings or glare or reflections, though I imagine it helps that I always wear a curved-brim ball cap and pull it down reasonably low to help block stray light. Aside from needing sufficient eye-relief, I have no complaints or issues using bins with glasses, it's totally natural to me.

I do have one odd interaction of coatings with my polarized prescription sunglasses (Maui Jim brand). I love the sunglasses as they are wraparound so they block more light and wind and just fit better. They work fine with my other binoculars but with my Zeiss SF 8x42 there is something odd going on in the way of polarization or coating interaction and, particularly when looking at water, but sometimes visible against large leafed / lush foliage, I get weird bronzy brown and purple colors and a not very pleasant viewing experience. It's generally not a problem in a desert or field or open on land environment but it's a no go on pelagics...
Exactly the same experience for me while using polarized prescription eyeglasses. I noticed this while on a boat in Newfoundland and, like you, I abandoned them for regular AR coated lenses. There's some interaction between the polarized lens and the bin I do not understand...but can happily address by removing the eyeglasses!

AR coatings are fantastic and only enhance my viewing pleasure.
Pileatus is offline  
Reply With Quote
Old Wednesday 8th August 2018, 16:06   #8
pbjosh
Registered User

 
Join Date: Apr 2013
Location: Buenos Aires
Posts: 627
Quote:
Originally Posted by Pileatus View Post
Exactly the same experience for me while using polarized prescription eyeglasses. I noticed this while on a boat in Newfoundland and, like you, I abandoned them for regular AR coated lenses. There's some interaction between the polarized lens and the bin I do not understand...but can happily address by removing the eyeglasses!

AR coatings are fantastic and only enhance my viewing pleasure.
Just for the sake of documentation in case anyone else ever finds this thread or finds this info useful, my Maui Jim sunglasses cause no problems with Swarovision 10x42, Conquest HD 8x42, with which I have used them extensively on pelagics. I've never noticed a problem with my Nikon M7 8x42 or M7 8x30 but haven't taken those on boats. I've looked through other people's bins from time to time on boats, including Zeiss FLs, Ultravids, Noctavids, other sizes of Swarovisions, EDG's, and not had any problems but those weren't extensive tests.
pbjosh is offline  
Reply With Quote
Old Wednesday 8th August 2018, 19:59   #9
james holdsworth
Consulting Biologist
 
james holdsworth's Avatar

 
Join Date: Oct 2009
Location: ontario
Posts: 3,112
My polarized sunglasses cause weird colour effects with almost all of my bins.
__________________
''serenity now....insanity later.'' - Lloyd Brawn
james holdsworth is offline  
Reply With Quote
Old Wednesday 8th August 2018, 23:00   #10
Tringa45
Registered User

 
Join Date: Dec 2017
Location: Cologne, Germany
Posts: 108
An optician told me that the current state of the art is seven-layer multicoatings, which can be applied to glass or plastic lenses. I now favour the standard plastic material, CR-39, as it is safer and lighter than glass, has better UV protection and has an Abbe number similar to crown glass (low dispersion). The coatings, apart perhaps from the top hydrophobic coating, should be harder than the base material so, treated with the same care as one's binoculars are quite durable. My CR-39 glasses are 18 months old and are cleaned once or twice daily with liquid soap under running water and dried off with a cosmetic tissue. Under a 10x loupe i can detect no damage.

I think there is a good case to be made for bifocals. There is only a slight loss of sharpness at intermediate distances around 1 m but there are no problems using them with bins and, despite having no astigmatism in my viewing eye, I usually leave my glasses on when using the scope. Another advantage apart from the cost is that one can easily see if the optician got the alignment right, which can't be seen with progressives.

John

Last edited by Tringa45 : Wednesday 8th August 2018 at 23:03.
Tringa45 is offline  
Reply With Quote
Old Thursday 9th August 2018, 16:22   #11
typo
Registered User

 
Join Date: Feb 2010
Location: Hertfordshire
Posts: 3,661
My two most recent glasses have lenses from Zeiss. I think they were both 1.6 index. The first (Premium Plus?) had a medium greenish reflection which darkened blues just a little, and is most noticable against a ble sky. The newer ones were a bit pricier (Precision Superb?). These have a very feint blue reflection. If I really concentrate I can spot a very slight shift to a warmer balance, but these are by far the best I've had for colour. I also found some Essilor lenses from around 10 years ago with a fairly strong purple reflection. The lens itself is now discoloured a little as well, giving quite a noticable boost in the yellow.

I use progressives, but have asked that that they start the transition a little lower than they would normally do so my distance vision is unaffected when using binoculars. One interesting feature of this latest design is they are corrected for both vertex (eye to lens) distance and tilt, adjusting the prescription separately for the distance and reading zones. There is probably only marginal benefit optically at my prescription, but it's a valuable feature for those who need stronger lenses. What was more useful was that I could specify the vertex distance I wanted. These now just clear my eyelashes, yet still allowed me to use models with a 15mm ER. My previous specs had an even shorter vertex distance, but needed a lot more cleaning.

David
typo is online now  
Reply With Quote
Old Thursday 9th August 2018, 17:41   #12
NDhunter
Registered User
 
NDhunter's Avatar

 
Join Date: Mar 2009
Location: ND
Posts: 3,786
David:

Thanks for that, I suspected there was some color issues that would affect the view.

Now we can see how complicated a prescription can become, with custom altering the view
in the lens.

Jerry
NDhunter is offline  
Reply With Quote
Old Thursday 9th August 2018, 18:40   #13
typo
Registered User

 
Join Date: Feb 2010
Location: Hertfordshire
Posts: 3,661
Jerry,

Perhaps I should point out that, at least with these latest Zeiss lenses, the colour shift is much more subtle than that of an ELSV or a SF.

David

Last edited by typo : Thursday 9th August 2018 at 18:49.
typo is online now  
Reply With Quote
Old Thursday 9th August 2018, 23:22   #14
Alexis Powell
Registered User

 
Join Date: Dec 2003
Location: LY+DG counties, Kansas, USA
Posts: 2,936
On eyeglasses lens coatings:

I prefer glass for its toughness with respect to scratch resistance. Scratched lenses or coatings are worse than no coatings (I have found). Coatings on glass scratch more easily than plain glass (I have found), and coatings on glass attract oil (because oleophobic coatings are not available for glass lenses, at least in the USA) which makes matters worse in other respects, so I use uncoated glass lenses. I've been very happy with them, but I always wear a hat to block lateral light.

On polarized lenses:

I find that polarized lenses (by themselves, apart from looking through bins) cause shifts in the appearances of birds that make even familiar species unrecognizable at first glance, so I never wear them while birding. They certainly cause problems with old roof bins without phase coating. Interesting that some users find that they cause problems with current bins.

On progressive lenses and alternatives:

I can't imagine how anyone tolerates progressive lenses even for regular viewing (unless absolutely necessary, as for someone entirely lacking accommodation), so my assumption is that their popularity (I see almost no one wearing standard bifocals) has more to do with vanity (avoiding the bifocal line) than with practicality. I had a set of bifocals made last year that allow me to focus on objects very close to my face (as I could when I was much younger), with the bifocal bit set a bit lower than usual on the lens. They work quite well with binoculars.

--AP
Alexis Powell is offline  
Reply With Quote
Old Thursday 9th August 2018, 23:45   #15
Pinewood
New York correspondent
 
Pinewood's Avatar

 
Join Date: Jun 2004
Location: New York, USA
Posts: 3,566
Quote:
Originally Posted by Alexis Powell View Post
On eyeglasses lens coatings:
...

On progressive lenses and alternatives:

I can't imagine how anyone tolerates progressive lenses even for regular viewing (unless absolutely necessary, as for someone entirely lacking accommodation), so my assumption is that their popularity (I see almost no one wearing standard bifocals) has more to do with vanity (avoiding the bifocal line) than with practicality. I had a set of bifocals made last year that allow me to focus on objects very close to my face (as I could when I was much younger), with the bifocal bit set a bit lower than usual on the lens. They work quite well with binoculars.

--AP
Hello Alexis,

I find progressive lenses rather convenient and I certainly do not wear them for appearance. However, I do find that there are different qualities for progressive lenses. I had my last specs filled by the N.Y. State University Eye Center, the optometry school. I found quite a difference in usefulness, sharper to the corners, and in contrast.

Happy bird watching,
Arthur
__________________
Bread is not enough. Give us circuses!
Pinewood is offline  
Reply With Quote
Old Friday 10th August 2018, 00:39   #16
WJC
Registered User
 
WJC's Avatar

 
Join Date: Jul 2005
Location: Twin Falls, Idaho
Posts: 2,045
Quote:
Originally Posted by Alexis Powell View Post
On eyeglasses lens coatings:

I prefer glass for its toughness with respect to scratch resistance.

--AP
Could someone please carve that in stone?

Bill
__________________
"What lies behind you and what lies before you are tiny matters compared to what lies within you."—Ralph Waldo Emerson
WJC is offline  
Reply With Quote
Old Friday 10th August 2018, 06:03   #17
typo
Registered User

 
Join Date: Feb 2010
Location: Hertfordshire
Posts: 3,661
Alexis,

I can't say I've ever been offered glass lenses by any of the opticians I've used over the years. I presumed it was because of cost, though I may have still opted for plastic for weight and shatter resistance reasons. I'll make a point of finding out more next visit.

I got my first prescription readers over 20 years ago and they did scratch. Apart from an unfortunate collision with a brick wall a 3 years ago, the scratch resistant coatings have done their job very well for the last few prescriptions. It's no longer an issue for me.

I was originally persuaded by my optometrist to have progressives because of the nature of my work. At the time I needing high acuity from 6" through to distance. I now realise I was fortunate in the lens design I was offered. I now know it had particularly low angular distortion. Unfortunately that particular design was discontinued and I've not found a replacement I'm completely happy with. You are normally advised that it can take up to 3 weeks to adjust to a new prescriptiom. I was still tripping over curbs after 3 months with one, top of the range, 'low distortion' design. It had 3.5 times more distortion than it's predecessor in my crude DIY test. Even my latest Zeiss lenses have double those originals and still bother me a little after six months. My wife, on the other hand, when given a comparable change in design felt she had completely adjusted by the time we got back to the car. Clearly progressives suite some better than others. The down side is that the top brand designs are expensive and there is always a new development round the corner. My guy really thinks I should try the latest double aspheric design. Not until I get my money's worth out of my current ones.

One thing I have learned is that choosing your optometrist is far more important than lens design or materials. I had tried different well known national chains and was never really satisfied that I was getting the best possible results. About 12 years ago I tried an independant guy. He took twice as long over the eye test and it resulted in a 2 line improvement on the chart. He's not cheap, but money well spent in my book.

David

Last edited by typo : Friday 10th August 2018 at 07:04.
typo is online now  
Reply With Quote
Old Friday 10th August 2018, 22:29   #18
Alexis Powell
Registered User

 
Join Date: Dec 2003
Location: LY+DG counties, Kansas, USA
Posts: 2,936
Typo--interesting experiences that I'll keep in mind if I ever need progressives.

I heartily agree that it is important to find a good optometrist or opthamologist, especially when one is hyper aware of one's visual performance as are, I'm sure, many of us on this forum. I've had several tweaks done w/prescriptions that are apparently nonstandard or that relate to something that I'm not supposed to be able to notice, but my guy is patient and enjoys the challenge of satisfying my vision correction needs.

--AP
Alexis Powell is offline  
Reply With Quote
Old Saturday 11th August 2018, 00:06   #19
perterra
Registered User
 
perterra's Avatar

 
Join Date: Nov 2011
Location: tx
Posts: 1,971
Quote:
Originally Posted by Alexis Powell View Post
On eyeglasses lens coatings:

I prefer glass for its toughness with respect to scratch resistance. Scratched lenses or coatings are worse than no coatings (I have found). Coatings on glass scratch more easily than plain glass (I have found), and coatings on glass attract oil (because oleophobic coatings are not available for glass lenses, at least in the USA) which makes matters worse in other respects, so I use uncoated glass lenses. I've been very happy with them, but I always wear a hat to block lateral light.

On polarized lenses:

I find that polarized lenses (by themselves, apart from looking through bins) cause shifts in the appearances of birds that make even familiar species unrecognizable at first glance, so I never wear them while birding. They certainly cause problems with old roof bins without phase coating. Interesting that some users find that they cause problems with current bins.

On progressive lenses and alternatives:

I can't imagine how anyone tolerates progressive lenses even for regular viewing (unless absolutely necessary, as for someone entirely lacking accommodation), so my assumption is that their popularity (I see almost no one wearing standard bifocals) has more to do with vanity (avoiding the bifocal line) than with practicality. I had a set of bifocals made last year that allow me to focus on objects very close to my face (as I could when I was much younger), with the bifocal bit set a bit lower than usual on the lens. They work quite well with binoculars.

--AP
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.

Plastics are popular because of the weight and impact resistance in my case. I have a pair of glass lens from a few years ago, they weigh 3 3/4 ounces, my high index polycarbonates weigh 3/4 ounce. Also in my line of work, glass lens are verboten. They fail miserably in impact protection.

Edited to add, I just weighed my daily wear Silhouettes eye glasses, they weigh exactly 1/2 oz with a stronger prescrip than the old glass lens.
__________________
"Chan eil aoibhneas gun Chlann Dhomhnaill"

Last edited by perterra : Saturday 11th August 2018 at 18:50.
perterra is offline  
Reply With Quote
Old Saturday 11th August 2018, 15:42   #20
looksharp65
Registered User
 
looksharp65's Avatar

 
Join Date: Feb 2010
Location: Varberg, Sweden
Posts: 1,856
Quote:
Originally Posted by NDhunter View Post
I am wondering how these newer optional coatings affect viewing with binoculars.

I don't wear eyeglasses, except for readers, I have noticed you can tell
when someone is wearing these, with the reflection off of the lens.

I suspect this also affects binocular viewing, and so also must affect color and brightness.

Does anyone know more about this ?

Jerry
Chiming in just briefly by request from Jerry. I've had to take a BF break due to health issues related to general overload.

Ergo:
Good AR coatings allow >99% of the incident light to pass through, this number goes for each surface.

The residual reflection is chosen to satisfy the customer's need to see they really paid for something visible. According to a top clerk on one of Germany's major lens manufacturers, the residual reflection could actually be made white, but that there's no demand for it, in fact on the contrary.

Another reason would be to put the brand's "hallmark" on the lenses to easily distinguish them from their competitors.
With few exceptions though, the residual reflection is greenish-turquoise, sometimes with a second in magenta.

In my book, 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.
But material characteristics of the lens like transmission at different wavelengths may definitely affect colour balance, in particular with thicker lenses.

I've said this before, but binoculars with >40 lens surfaces and mirror coatings is an entirely different thing. Reaching a reasonably neutral colour balance requires intricate calculations involving glass colour and customised coatings for every individual lens or prism surface.

When I made experiments with a single-side blue photo filter (i think it was 80A) and the Nikon HG/Venturer/Premier 10x32, I got decidedly better perceived colours but at the expense of lower transmission rate.
Two AR coated spectacle lens surfaces can't get anywhere close to that effect.


Conversely, current coloured mirror sunglasses reflect so much of particular wavelengths that a major colour shift can be noted. However, it is not possible to determine how the colour balance of the tinted lenses is without the mirror.

Take care, all!

//L
__________________
http://en.wikipedia.org/wiki/Visby_lenses - The Viking optics
http://www.youtube.com/watch?v=LuBYpRkbzrs - The Viking War Cry
looksharp65 is offline  
Reply With Quote
Old Saturday 11th August 2018, 18:12   #21
WJC
Registered User
 
WJC's Avatar

 
Join Date: Jul 2005
Location: Twin Falls, Idaho
Posts: 2,045
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.
__________________
"What lies behind you and what lies before you are tiny matters compared to what lies within you."—Ralph Waldo Emerson

Last edited by WJC : Saturday 11th August 2018 at 18:15.
WJC is offline  
Reply With Quote
Old Saturday 11th August 2018, 19:04   #22
typo
Registered User

 
Join Date: Feb 2010
Location: Hertfordshire
Posts: 3,661
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/...on-silver.html

Last edited by typo : Saturday 11th August 2018 at 20:28.
typo is online now  
Reply With Quote
Old Saturday 11th August 2018, 19:42   #23
typo
Registered User

 
Join Date: Feb 2010
Location: Hertfordshire
Posts: 3,661
Here's a little online colour generator that some might find interesting.
http://www.csfieldguide.org.nz/en/in...xer/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 is online now  
Reply With Quote
Old Saturday 11th August 2018, 21:49   #24
WJC
Registered User
 
WJC's Avatar

 
Join Date: Jul 2005
Location: Twin Falls, Idaho
Posts: 2,045
Quote:
Originally Posted by typo View Post
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/...on-silver.html
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!

Bill
__________________
"What lies behind you and what lies before you are tiny matters compared to what lies within you."—Ralph Waldo Emerson
WJC is offline  
Reply With Quote
Old Saturday 11th August 2018, 22:01   #25
typo
Registered User

 
Join Date: Feb 2010
Location: Hertfordshire
Posts: 3,661
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

Last edited by typo : Saturday 11th August 2018 at 22:22.
typo is online now  
Reply With Quote
Advertisement
Reply


Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Eyeglasses bh46118 Binoculars 29 Tuesday 25th November 2014 07:43
Asking for Suggestion on viewing with eyeglasses & avoiding smudges on my eyeglasses MikeBMc Say Hello 3 Tuesday 11th March 2014 08:20
Eyeglasses for birding Kevin Purcell Binoculars 16 Wednesday 8th October 2008 17:45
Binoculars: With or without eyeglasses? etc Binoculars 13 Monday 24th March 2008 11:45
eyeglasses and eyepieces elpuffino Spotting Scopes & tripod/heads 25 Saturday 11th March 2006 15:05

{googleads}

Fatbirder's Top 1000 Birding Websites

Help support BirdForum

Page generated in 0.20773292 seconds with 35 queries
All times are GMT. The time now is 08:46.