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Is ED Material in Binoculars All Hype? (1 Viewer)

A

AlanFrench

Well-known member
I had a chance last week to talk to an optical designer who specializes in very high end optics about ED material in binoculars. I asked if there was any advantage to using ED material in a low power (7 to 10x) binocular. His response was an unequivocal "No."

I notice that more and more companies are advertising ED binoculars, but am increasingly convinced they are responding to perception rather than reality.

Clear skies, Alan
 
Alan,

I examined the Audubon 8.5x44 ED in a shop and saw no reason to purchase it. The colors did not appear special.

Happy bird watching and clear skies,
Arthur Pinewood :scribe:
 
AlanFrench said:
I had a chance last week to talk to an optical designer who specializes in very high end optics about ED material in binoculars. I asked if there was any advantage to using ED material in a low power (7 to 10x) binocular. His response was an unequivocal "No."

I notice that more and more companies are advertising ED binoculars, but am increasingly convinced they are responding to perception rather than reality.

Clear skies, Alan
Click to expand...

Alan,

In marketing, perception is reality. Thankfully, you and I enjoy the consistently agreeable opinions of fellow BF'ers that guide us, unerringly, in our decision-making processes.

John
 
Alan

According to Stephen Ingrahams article (Late of "BVD”) - Bird Worthy Binoculars, some of us have been enjoying ED glass elements within our binoculars for years without even knowing it. Apparently Leica and other high end glasses utilise it. It would be interesting to know if Swarovski and Nikon also employ at least some ED glass in their top end binoculars.

Mick Baron
 
AlanFrench said:
I had a chance last week to talk to an optical designer who specializes in very high end optics about ED material in binoculars. I asked if there was any advantage to using ED material in a low power (7 to 10x) binocular. His response was an unequivocal "No."

I notice that more and more companies are advertising ED binoculars, but am increasingly convinced they are responding to perception rather than reality.

Clear skies, Alan
Click to expand...

Alan: I have always found internally focussing roof prism binoculars to have rather a lot of CA to the extent that it sometimes makes a bird ID impossible, and at other times it is aesthetically displeasing. (Seeing a bird with three heads is unnatural.) Hence I welcome anything that leads to less CA, whatever the explanation.

As you know I own a Zeiss 8x42 FL and I can confirm that it does have substantially less CA than any other binocular in its class. It is not marketing hype: it is real.

I recently tried another internally focussing roof prism binocular (an 8x42 APO binocular with triplet objectives). That one also showed very little CA to the extent that it was on a par with a typical porro prism glass. I asked the manufacturer about the use or not of ED glass in the objectives but unfortunately they did not reply.

So if we accept what you say, we have to conclude that Zeiss and others are willing to add something that significantly increases the manufacturing cost of a product for marketing hype alone. We also have to assume that they have found a way to reduce CA and that they prefer to credit the superfluous ED objectives with that feat. Let's assume that the ED elements are superfluous and that some other feature explains the exceptionally low CA. In that case would it not make sense to leave out the ED glass, trumpet the exceptional control of CA by inventing a suitable marketing term, and sell the binocular a bit cheaper. Thus we would all win. The binocular could be cheaper, it would be better than competing products (at least in terms of CA) and Zeiss could make a bit more more profit. In short I reckon that your suggestion just does not make sense.

In fact I would say the opposite. Manufacturers are using hype to kid us into thinking that their instruments are near perfect, when they are not. Before the advent of phase coating manufacturers were selling binoculars that were not even as sharp as a much cheaper porro prism glass, but of course they kept quiet about that small issue. (Some people might dismiss phase coating as snake oil on the grounds that a 42mm objective with 8x magnification produces more detail than the eye can use.) And of course some manufacturers like to impress us with talk of dielectric coatings on the prisms, but do not mention that the reason of them is to overcome a shortcoming of Schmidt Pechan roof prisms !!! I am sure that some people have considered a porro prism glass to be inferior due to the absence of fancy dielectric coatings.

The optical designer could of course be wrong. (Does he have experience of designing roof prism binoculars?) I suspect he has made some false assumptions and then reached a conclusion on that basis. It sounds a bit like the resolution issue i.e. a naive interpretation of theory.

Leif

PS The Nikon 8x32 SE does not use ED glass.
 
Leif said:
In fact I would say the opposite. Manufacturers are using hype to kid us into thinking that their instruments are near perfect, when they are not. Before the advent of phase coating manufacturers were selling binoculars that were not even as sharp as a much cheaper porro prism glass, but of course they kept quiet about that small issue. (Some people might dismiss phase coating as snake oil on the grounds that a 42mm objective with 8x magnification produces more detail than the eye can use.) And of course some manufacturers like to impress us with talk of dielectric coatings on the prisms, but do not mention that the reason of them is to overcome a shortcoming of Schmidt Pechan roof prisms !!! I am sure that some people have considered a porro prism glass to be inferior due to the absence of fancy dielectric coatings.

The optical designer could of course be wrong. (Does he have experience of designing roof prism binoculars?) I suspect he has made some false assumptions and then reached a conclusion on that basis. It sounds a bit like the resolution issue i.e. a naive interpretation of theory.

Leif

PS The Nikon 8x32 SE does not use ED glass.
Click to expand...

Interesting thread. What I've always heard as gospel about ED in binoculars is that objective lens size (rarely over 50mm for birders) is too small for it to make alot of difference. The Audubon EDs from Swift seem a great case in point. Side by side the ED model (to my eyes) doesn't offer much in terms of tighter resolution and reducing CA (which is negligible for the most part anyway) although at real low lights, I note CA in the non-ED, while not much at all in the ED. As Leif adeptly notes, prism type, design, and quality have as much to do with end optical qualilty as objective lens materials...

Jason
 
ED glass does make a significant difference. Compare the same binos, one with and one without ED glass and you will see a significant difference.

ranburr
 
ranburr said:
ED glass does make a significant difference. Compare the same binos, one with and one without ED glass and you will see a significant difference.

ranburr
Click to expand...

Some while back Stephen Ingraham - possibly in response to a comment by Alan French - stated that he was one of the people that contributed to the design of the FL range. They were allowed to try prototypes with and without ED elements, and they concluded that the ED elements DID make a noticeable difference.

Leif
 
Leif said:
[SNIP]
As you know I own a Zeiss 8x42 FL and I can confirm that it does have substantially less CA than any other binocular in its class. It is not marketing hype: it is real.
[SNIP]

What binoculars have you compared them to? I have the 7x42 Swarovski SLCs, and they show no significant chromatic aberrations. There is a bit of lateral color at the edge of the field, and it is obvious on a white, sunlit daisy against and dark green, forest background. Lateral color, however, is largely an eyepiece problem.

They do not show any evidence of secondary color.

Clear skies, Alan
Click to expand...
 
Leif said:
[SNIP]
The optical designer could of course be wrong. (Does he have experience of designing roof prism binoculars?) I suspect he has made some false assumptions and then reached a conclusion on that basis. It sounds a bit like the resolution issue i.e. a naive interpretation of theory.
[SNIP]
Click to expand...

The gentleman in question has extensive experience designing high end APOs, and a variety of other telescopes. The addition of a roof prism to an optical system only serves to erect the image and introduce additional aberrations, so an understanding of how the use of an ED element in a lens changes performance and the limitations on low-power viewing is all that is needed here.

I note that some folks on this forum previously said they could not see any difference between ED scopes and non-ED scopes at low power, and there have also been comments that the Swift ED binoculars did not show an improvement over the non-ED version.

In using astronomical refractors I find that normal achromats work just fine at low powers, and that the real advantage to APOs and the improved color correction is in high power viewing.

At any rate, I would love to see the non-ED version of the Zeiss versus the ED version in person. I fear I am a terrible skeptic when it comes to reports on optical equipment - over the years I have found most reviews and reports are little more than someone's very subjective opinion, and it is very hard to find objective information. People often let their enthusiasm shade their opinions, and this can be catching.

Clear skies, Alan
 
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AlanFrench said:
Leif said:
[SNIP]
As you know I own a Zeiss 8x42 FL and I can confirm that it does have substantially less CA than any other binocular in its class. It is not marketing hype: it is real.
[SNIP]

What binoculars have you compared them to? I have the 7x42 Swarovski SLCs, and they show no significant chromatic aberrations. There is a bit of lateral color at the edge of the field, and it is obvious on a white, sunlit daisy against and dark green, forest background. Lateral color, however, is largely an eyepiece problem.

They do not show any evidence of secondary color.

Clear skies, Alan
Click to expand...

I have used many samples of many instruments, often for long periods in the field, over many years. Recently I compared my Zeiss 8x42 FL side by side with my Swarovski 8.5x42 EL, Nikon 8x32 SE and Nikon 8x40 Egret. All (except the Zeiss) have some on-axis CA which cannot be lateral CA. (Lateral CA is also known as CA of magnification as it creates multiple differently sized concentric images.) The EL has a bit more on-axis CA than I would like, though I know that many people do not notice it. It is only visible in certain lighting e.g. black bird against white sky. All (including the Zeiss) have some off-axis CA (possibly lateral CA). The Zeiss has the least, though the Nikon SE and Nikon Egret come close. The Swaro EL has noticeably more. I also once owned a Nikon 8x42 HG but it had too much CA for my taste (going by memory I would say that it had more than the Swaro). I also once owned a Steiner 10x40 RockyS, an awful binocular with a soft image (no phase coating?) and huge amounts of CA. I have tried 3 Nikon 8x32 HG and several Leica 8x32 BN and they show very significant CA to the extent that I do not like using them. I have also tried many others (such as Swaro 8x32 EL, Leica 8x42 BN, Leica 8x42 Ultravid and so on) and the presence of noticeable CA is common to ALL internal focussing roof prism binoculars, with the exception of the FL range, an 8x42 APO, and compacts e.g. Swaro 8x20 B. The Zeiss 8x30 BGAT, Nikon 8x32 SE and 8x40 Egret have very little CA.

Anyway, which roof prism binoculars have you tested in the field?

Many people do not see CA, so perception does play a role, and I would always advise people to use their own eyes to decide for themselves. The existence of CA is real, but the decision as to whether or not it is significant is subjective. Many people use roof prism binoculars and are unaware of CA and in some respects I envy them. At the end of the day all that matters is that the user gets enjoyment from a binocular.

Over the years I have had several people tell me that I do not see CA through low power binoculars because 40mm objectives are too small. Sometimes the postings have been quite rude/aggressive. For some reason the rude postings always come from amateur astronomers. There seems to be a slightly contemptuous tone from some amateur astronomers along the lines of "birders are ignorant about optics". It is sad to hear such disparaging remarks. (I recently looked at the Cloudy Nights site and found an amateur astronomer slagging off birders.) I have heard reports of CA from enough respected sources that I trust my own observation skills. (See BVD, Alula and so on.)

The BVD site has a review of the Swarovski 7x42 SLC:

http://www.betterviewdesired.com/NewRoof.html

Stephen Ingraham states that the Swaro 7x42 SLC "show an abnormally large amount of uncorrected chromatic aberration". I have not used a sample, so I cannot comment. However, I have used a Swarovski 8x30 SLC, and that also has noticeable CA, to a degree that I feel uncomfortable with, although most people would probably consider it to be fairly minor. My suspicion is that like many people you do not see CA for psychological reasons.

Leif
Click to expand...
 
Well, nothing scientific from me, but I am colour blind according to all those tests with the coloured dots. I've never felt that I was missing anything colourwise, or to put it another way I can see all different colours more or less the same as anyone else. My wife and I will sometimes disagree as to the exact shade or degree of colour but it's only minor differences. I just can't see the damned numbers in the dots.

I use the Swift Audubons with the ED glass and any colour looks to be much more saturated than when using my wifes binoculars (RSPB FGC PC,[iirc]) or in fact any other modern roof prism binos I've tried.

I used a pair of Swarovskis at a field day at Pulborough Brooks last year and everything had a definite green cast to it, the Leica Ultravids I tried were very bright but all colours had a slightly washed out look to them which is the same effect as when I use my wifes bins.

So, like most things with bins I would suggest it is very subjective according to your own eyesight.
 
I get CA through my Leica 8x32 binoculars it only appears when I tilt the bins upwards & view with the bottom half of the eyepiece(hope this makes sense)looking straight them though there is no CA.

Cheers Steve.
 
stevo said:
I get CA through my Leica 8x32 binoculars it only appears when I tilt the bins upwards & view with the bottom half of the eyepiece(hope this makes sense)looking straight them though there is no CA.

Cheers Steve.
Click to expand...

Misplacement of the eye in the exit pupil produces very obvious color problems, and is a good reason to carefully set the interpupillary distance.

Clear skies, Alan
 
First, thanks for the more detailed description of the binoculars you have used.

Leif said:
Anyway, which roof prism binoculars have you tested in the field?
[SNIP]

Swarovski EL 8.5x42, B&L Discoverer 7x42, Zeiss 7x42 Classic, Zeiss Victory 8x42 original and II, are the only ones that come to mind right now.

Many people do not see CA, so perception does play a role, and I would always advise people to use their own eyes to decide for themselves. The existence of CA is real, but the decision as to whether or not it is significant is subjective. Many people use roof prism binoculars and are unaware of CA and in some respects I envy them. At the end of the day all that matters is that the user gets enjoyment from a binocular.

Over the years I have had several people tell me that I do not see CA through low power binoculars because 40mm objectives are too small. Sometimes the postings have been quite rude/aggressive. For some reason the rude postings always come from amateur astronomers. There seems to be a slightly contemptuous tone from some amateur astronomers along the lines of "birders are ignorant about optics". It is sad to hear such disparaging remarks. (I recently looked at the Cloudy Nights site and found an amateur astronomer slagging off birders.) I have heard reports of CA from enough respected sources that I trust my own observation skills. (See BVD, Alula and so on.)

The BVD site has a review of the Swarovski 7x42 SLC:

http://www.betterviewdesired.com/NewRoof.html

Stephen Ingraham states that the Swaro 7x42 SLC "show an abnormally large amount of uncorrected chromatic aberration". I have not used a sample, so I cannot comment. However, I have used a Swarovski 8x30 SLC, and that also has noticeable CA, to a degree that I feel uncomfortable with, although most people would probably consider it to be fairly minor. My suspicion is that like many people you do not see CA for psychological reasons.

Leif
Click to expand...

Leif,

You comment that perception may play a role here. How about simply variations in eye sight? I waded through a book on visual instrumentation, and there were several chapters on the eye and vision, and it was clear that vision varies from person to person, and that our vision has a big effect when using low power optical instruments. This may at least partially account for the differing perception of various binoculars.

I quite clearly see on-axis, secondary color in achromatic telescopes, so it is odd that I do not see it in my 7x42 SLCs if it is indeed present.

Alan
Click to expand...
 
Leif said:
[SNIP]
Over the years I have had several people tell me that I do not see CA through low power binoculars because 40mm objectives are too small. Sometimes the postings have been quite rude/aggressive. For some reason the rude postings always come from amateur astronomers. There seems to be a slightly contemptuous tone from some amateur astronomers along the lines of "birders are ignorant about optics". It is sad to hear such disparaging remarks. (I recently looked at the Cloudy Nights site and found an amateur astronomer slagging off birders.) I have heard reports of CA from enough respected sources that I trust my own observation skills. (See BVD, Alula and so on.)
[SNIP]
Leif
Click to expand...

Leif

I am not quite sure why you bring this up, unless, perhaps, you are including me in that group. Personally, I find the reviews on Cloudy Nights are generally not very helpful or well done, and there is certainly enough ignorance about optics to go around. The world of amateur astronomy is fortunate to have a couple of optical designers who are quite willing and able to explain things. Unfortunately, it seems to be an uphill battle. I really wish the birding world had someone involved in the optical design and manufacture of binoculars willing to share his or her knowledge. I'd very much like a better understanding of their design and, especially, the eye's effect on their use. The latter seems pretty much ignored, but it is an important factor in what we see.

At any rate, back to my Feederwatch count....

Clear skies, Alan
 
AlanFrench said:
First, thanks for the more detailed description of the binoculars you have used.



Leif,

You comment that perception may play a role here. How about simply variations in eye sight? I waded through a book on visual instrumentation, and there were several chapters on the eye and vision, and it was clear that vision varies from person to person, and that our vision has a big effect when using low power optical instruments. This may at least partially account for the differing perception of various binoculars.

I quite clearly see on-axis, secondary color in achromatic telescopes, so it is odd that I do not see it in my 7x42 SLCs if it is indeed present.

Alan
Click to expand...

Alan: I have seen a photo of snow taken through a premium roof prism binocular - I am fairly sure it was the Nikon 8x42 HG, and that it was posted on BF - and purple colour fringing was obvious, even fairly near the optical axis. It was exactly as I would have expected from my own experiences, so I am certain that it is a property of the intrument, and not the eye. (Of course you could argue that it was the camera sensor and/or lens that caused the aberration. Although I don't think it was, the effect of the lens/sensor could be tested by taking a picture without the binocular. I'm not sure if the photographer (Gorank?) did that check, or made a comment on that issue. My own experience of small digital cameras is that they do produce noticeable CA, but much less than in the binocular photo c.f the digiscoping images on BF.)

My understanding is that for some reason the brain often filters out CA, and presumably other aberrations. I have heard it said that the eye is a poor optical instrument, and that the eye reconstructs an image, based on a mix of reality and expectation, hence the reason why so many optical illusions exist. I have sometimes looked at something, thought it was a given object, only to realise a few seconds later that it was something totally different.

You are right that the eye enters the equation, and that we all have differences. I can't say that I understand the issues involved, although as I think you have pointed out, in low light when the pupil dilates, irregularities in the cornea come into play, as well as differences due to using different photo receptors within the retina. I also think that people have differences in visual acuity, though I presume that is due to differences in the cornea rather than the retina. A nice high level description of the issues would be nice, though I have not found one on the net.

Leif
 
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Leif said:
Alan: I have seen a photo of snow taken through a premium roof prism binocular - I am fairly sure it was the Nikon 8x42 HG, and that it was posted on BF - and purple colour fringing was obvious, even fairly near the optical axis. It was exactly as I would have expected from my own experiences, so I am certain that it is a property of the intrument, and not the eye. (Of course you could argue that it was the camera sensor and/or lens that caused the aberration. Although I don't think it was, the effect of the lens/sensor could be tested by taking a picture without the binocular. I'm not sure if the photographer (Gorank?) did that check, or made a comment on that issue. My own experience of small digital cameras is that they do produce noticeable CA, but much less than in the binocular photo c.f the digiscoping images on BF.)
[SNIP]
Leif
Click to expand...

Leif,

I suspect aberrations of the camera lens could indeed bias the results. The other issue is whether the camera was seeing the entire exit pupil. If so, it would register more aberrations than our eye would.

The 6mm exit pupil of the binoculars would be stopped down to at least 3mm by the eye on a bright sunny day, increasing the f/ratio and reducing aberrations both from the objective and from the eyepiece.

Clear skies, Alan
 
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