swaro news (1 Viewer)

[Holger Merlitz]

Dear Bill,

Thanks for the advanced credentials

Obviously, this 'Absam ring' does not really affect optical performance - with the exception of an observer with accommodation range zero (e.g. after a lens-replacement surgery). I thus regard it to be a curiosity rather than a nuisance. Does it show up exclusively in Swaro-binoculars? Perhaps yes, because so far it has been Swaro who exercised that aggressive field-flattening approach, while Zeiss/Leica usually exhibit some residual field curvature.

Since not every high order aberration has got a name, I fear there is little chance to establish a term such as 'Brock-error' within the realm of technical literature. I may be wrong, so perhaps you might suggest it to the SPIE community?

Cheers,
Holger

 

[PeterPS]

Dear Bill,

Thanks for the advanced credentials

Obviously, this 'Absam ring' does not really affect optical performance - with the exception of an observer with accommodation range zero (e.g. after a lens-replacement surgery). I thus regard it to be a curiosity rather than a nuisance. Does it show up exclusively in Swaro-binoculars? Perhaps yes, because so far it has been Swaro who exercised that aggressive field-flattening approach, while Zeiss/Leica usually exhibit some residual field curvature.

Since not every high order aberration has got a name, I fear there is little chance to establish a term such as 'Brock-error' within the realm of technical literature. I may be wrong, so perhaps you might suggest it to the SPIE community?

Cheers,
Holger

Hi Holger,
How about the many Nikon binos with field flattening, especially the WX? Also it seems to me that in principle such a ring could be the result of even first-order correction of field curvature---when you want the edge to be sharp you could overcompensate the required -d's near the edge using even a single lens, agree?
Peter

 

[Holger Merlitz]

Hi Peter,

I haven't seen that phenomenon with the Nikon WX, but may also add that the edge-sharpness of the WX is probably not quite as perfect as found with the Swaro.

Since I am no lens designer, I cannot comment on your last question. I realize that Swaro uses a group of two lenses for field flattening, that was the origin of my 'educated guess'

Cheers,
Holger

 

[pbjosh]

Hi Holger,
How about the many Nikon binos with field flattening, especially the WX? Also it seems to me that in principle such a ring could be the result of even first-order correction of field curvature---when you want the edge to be sharp you could overcompensate the required -d's near the edge using even a single lens, agree?
Peter

I'm far from knowledgeable about optics, but in one lens, unless it is an aspheric lens, it seems counter-intuitive to achieve a change from over to under correction (or vice versa) in the middle of the field of view rather than in the center or edge. And if the lens is aspheric, I wouldn't be qualified to say whether it's still a first-order correction or not, that's more semantics perhaps, and an aspheric lens is technically one piece of glass but acts as multiple lenses combined, you might argue / understand.

Again, I'm no expert on the optical side - I'm making some logical leaps here from the realm of polyfitting / curve fitting (approximating a shape - in this case a flat line - via polynomial functions). Granted, the surface of a spherical lens is not readily approximated by a polynomial either, but I think the same basic principles are applicable in this simplified analogy?

 

[Gijs van Ginkel]

We have a country covered in snow this afternoon, time to compare the images by eye of some binoculars using a brick wall as source of investigation.
-1- As I reported earlier: the NL pure 8x42 does not show a Brock ring as seen by my eyes and the images are perfectly sharp up to the edge.
-2- The Zeiss Victory SF 8x32 is not sharp up to the very edge, there is a small ring of unsharpness at the very edge and that turns into a blue ring if I observe the snow covered surface, something reported earlier by Jan van Daalen and later by me.
Is it important? For me it is not but some ingeneous name inventor might call it a Zeiss ring, also good for some discussion here.
-3- Got hold of an EL-SV 8,5 x42 and I could not detect a Brock ring, whatever I tried.
Gijs van Ginkel

 

[Renze de Vries]

We're not likely to ever get agreement about whether this phenomenon exists because it can be visible or invisible depending on the pupil position unconsciously adopted by different observers when they swivel their eye to look for it. I can turn it on or off by simply shifting the position of my eye's pupil a little to apply more or less vignetting to that area of the FOV. The increase in field curvature is still there even when I don't see it. It becomes invisible to me when the DoF of my eye is increased by introducing more vignetting.

Thanks for the excellent explanation Holger. We're in complete agreement about what it is except I've been calling it a bump in field curvature and you called it a ripple.

Henry

The logic escapes me here. I would say that if the phenomenon, a ring of softness in the viewing circle, is visible, than it's there, it exists. That it can be made invisible as well, or can't be seen by all human beings, doesn't change its reality.
I think that it's pretty safe to conclude from the (beautiful) discussion here that a ring of softness (the infamous Absam ring) is inherent to the design of the Swarovski EL-SV and NL Pure. Just as a zone of sharpness at the edge is part of the design. Also, it's clear from Holgers's explanation that these two things are related.
If you allow me yet another opinion about the SV's and NL's design, what strikes me is that Swarovski made both design traits visible as well as invisible. I mean you have to look pretty awkward through the binocular, working your way through a dose of nasty black outs, to see the sharp edge in full glory.

Renze

 

[pbjosh]

-2- The Zeiss Victory SF 8x32 is not sharp up to the very edge, there is a small ring of unsharpness at the very edge and that turns into a blue ring if I observe the snow covered surface, something reported earlier by Jan van Daalen and later by me.
Is it important? For me it is not but some ingeneous name inventor might call it a Zeiss ring, also good for some discussion here.

I've found that I can see the blue ring in my 8x32 SF as well, under the right circumstances, if I look for it. I have to kind of shift my eyes around unnaturally and/or un-center my view but it is possible to see it.

I also agree that it is utterly unimportant and doesn't affect the view at all.

My initial impression of the 8x32 SF is that there is basically nothing (for me) to complain about. I believe it will end up being my main binocular and will result in the sale of a few others.

 

[PeterPS]

I've found that I can see the blue ring in my 8x32 SF as well, under the right circumstances, if I look for it. I have to kind of shift my eyes around unnaturally and/or un-center my view but it is possible to see it.

I also agree that it is utterly unimportant and doesn't affect the view at all.

My initial impression of the 8x32 SF is that there is basically nothing (for me) to complain about. I believe it will end up being my main binocular and will result in the sale of a few others.

I saw the "blue ring" in my SF 10x42 about 5 years ago (although I wouldn't call it a ring, as at least in my case it shows like diffuse bluish reflections in the lower part of the FoV). I discussed it with Gerald Dobbler and his answer was that if you look at the edge of the FoV several "distortions" become visible, I guess his implicit advice was that I should enjoy the center view and don't look at the edges.

 

[henry link]

The logic escapes me here. I would say that if the phenomenon, a ring of softness in the viewing circle, is visible, than it's there, it exists. That it can be made invisible as well, or can't be seen by all human beings, doesn't change its reality.
I think that it's pretty safe to conclude from the (beautiful) discussion here that a ring of softness (the infamous Absam ring) is inherent to the design of the Swarovski EL-SV and NL Pure. Just as a zone of sharpness at the edge is part of the design. Also, it's clear from Holgers's explanation that these two things are related.
If you allow me yet another opinion about the SV's and NL's design, what strikes me is that Swarovski made both design traits visible as well as invisible. I mean you have to look pretty awkward through the binocular, working your way through a dose of nasty black outs, to see the sharp edge in full glory.

Renze

Hi Renze,

Off-axis vignetting certainly must be the least understood and most under-appreciated factor affecting how we subjectively experience field curvature. Your last sentence is a good description of it. Those kidney bean blackouts are nothing but vignetting reaching such a high level that it completely obstructs the exit pupil at that spot in the field. You have to "work your way" through the blackouts by finding pupil positions that re-open or at least partially re-open the exit pupil. In my post #71 I suggested a test that allows you to clearly see how this happens. I doubt that anybody tried it, so here is the post again.


"I'm going to work with this problem more later today, but In the meantime I'm going to suggest a home test to observe how well your eye aligns with the exit pupil and how much off-axis vignetting you experience.

This test requires an artificial star placed about 5 meters away from the observer. I've been using a bright led flashlight with aluminum foil stretched over the lens and punctured with a pin to make a pinhole. Use only one eye, focus the binocular at infinity and observe the pinhole. You should see a disc of light, which is either an image of the objective lens of the binocular or your own eye's pupil, whichever is smaller. If you move the binoculars up and own and side to side you can see how your pupil and the exit pupil vignette each other when they are misaligned. Move the disc off-axis and you will see how vignetting interferes with the clear aperture of the binocular and how the amount of vignetting is affected by your pupil movements.

I think you will see that when you look off-axis the model of a perfectly round exit pupil with the eye's round pupil nicely centered on it quickly gives way to a myriad of overlapping apertures creating various cat's eye shaped exit pupils which you can consciously open up to nearly circular shapes or close down to slits depending on the exact position of your pupil."


Work with this test for 15 minutes and I think you will see how the vignetting can act to turn the binocular's off-axis exit pupils into narrow slits that act as stop downs for the pupil of your eye, increasing its DOF and thus allowing the eye to tolerate more field curvature than it can when its pupil is unobstructed.

Henry

 

[WJC]

Dear Bill,

Thanks for the advanced credentials

Obviously, this 'Absam ring' does not really affect optical performance - with the exception of an observer with accommodation range zero (e.g. after a lens-replacement surgery). I thus regard it to be a curiosity rather than a nuisance. Does it show up exclusively in Swaro-binoculars? Perhaps yes, because so far it has been Swaro who exercised that aggressive field-flattening approach, while Zeiss/Leica usually exhibit some residual field curvature.

Since not every high order aberration has got a name, I fear there is little chance to establish a term such as 'Brock-error' within the realm of technical literature. I may be wrong, so perhaps you might suggest it to the SPIE community?

Cheers,
Holger

"so perhaps you might suggest it to the SPIE community?"

R U Nutz! 😱

 

[Renze de Vries]

Henry,

I was very pleased with your contribution #45 and subsequent posts and immediately recognized the issue. Thanks for that, as it clarifies in detail the complexities in ergonomics and face-binocular interface when using binoculars. More often than not we have to learn to properly use our instruments.

However, when I felt that you tended to deny the existence, the reality of the 'ring' in the SV and NL I liked to point to the design. It's not in our imagination, it's not in our individual way of seeing, it's not behaviour, it's in the instrument.

Renze

 

[Tringa45]

The whole discussion on the "Absam Ring" reminds me of conspiracy theories.
The Swarovski EL SV when introduced had a freedom from rectilinear distortion, field curvature and astigmatism like no previous binocular in history - but there just had to be a fault somewhere, real or imagined.
I had my 10x42 EL SV this afternoon on a tripod viewing a strongly illuminated 1951 USAF slide. For me the Absam Ring has as much credibility and relevance as UFOs.

John

 

[etudiant]

As a birder with much less than perfect eyesight, I have to wonder whether this is becoming a religious rather than a practical discussion.
Older birders often have issues that go well beyond the usual topics of eye relief or FoV. Astigmatism is common at my age, but not discussed here, presumably because the glasses we wear should perfectly correct that, except that they do not. Absam ring to me seems a more theoretical problem, discernible only to a fortunate few who have really good eyesight.
So perhaps the Absam ring discussion should be limited to those who enjoy that blessing. For the rest of us, it seems a non issue.

 

[Maljunulo]

It is my personal opinion that every "older birder" should develop cataracts and have their original equipment lenses replaced with implants.

Unless you have oddly shaped eyeballs and severe astigmatism, or some sort of retinal problems, you will be able to see like a twelve-year old, and using the very best binoculars will be an incredible and almost sensuous experience.

(again, just my opinion, irrespective of the existence or non-existence of the Absam ring)

 

[pm42]

The whole discussion on the "Absam Ring" reminds me of conspiracy theories.

I would not go this far but I get this feeling that some people are desperately trying to find faults in the best binoculars in the market.

It's ok, people do what they want but this is not the most interesting threads as far as I'm concerned.

 

[james holdsworth]

There are two camps in most of these discussions..those that see everything as a fault and those that cannot, ever, see any fault whatsoever. I’ve learned to mostly ignore both...lol.

 

[Maljunulo]

It's ok, people do what they want but this is not the most interesting threads as far as I'm concerned.

I thought it was very interesting when the folks who know what they are talking about were speaking, but the signal to noise ratio decreased as it went on.

 

[dries1]

Come on UFOs do exist, don't they.

Andy W.

 

[elkcub]

Dear Bill,

Thanks for the advanced credentials

Obviously, this 'Absam ring' does not really affect optical performance - with the exception of an observer with accommodation range zero (e.g. after a lens-replacement surgery). I thus regard it to be a curiosity rather than a nuisance. Does it show up exclusively in Swaro-binoculars? Perhaps yes, because so far it has been Swaro who exercised that aggressive field-flattening approach, while Zeiss/Leica usually exhibit some residual field curvature.

Since not every high order aberration has got a name, I fear there is little chance to establish a term such as 'Brock-error' within the realm of technical literature. I may be wrong, so perhaps you might suggest it to the SPIE community?

Cheers,
Holger

Hi Holger,

I'm too lazy to look for the specific post again, but in 2012 Brock asserted that he found a similar defocused ring in all 'flat field' binoculars. When questioned about why he seemed to be attacking Swarovski rather than the others, he allowed as how he could just as well have used "Nikon ring" for the SE and LXL, although it was much smaller (he said).

Personally, I don't have a problem with <name it> rings because I'm perceptually allergic to so-called flat field designs.

Regards,
Ed

BTW, using the 'Search" feature, Brock's most recent posts can be found from late last year.

 

[etudiant]

It is my personal opinion that every "older birder" should develop cataracts and have their original equipment lenses replaced with implants.

Unless you have oddly shaped eyeballs and severe astigmatism, or some sort of retinal problems, you will be able to see like a twelve-year old, and using the very best binoculars will be an incredible and almost sensuous experience.

(again, just my opinion, irrespective of the existence or non-existence of the Absam ring)

I had glasses as a 12 year old and needed them, so the recommendation's main impact on me would be to enhance my ophthalmologists net worth.
My personal opinion is that these discussions of the merits of unstabilized binoculars can be grouped with the analogous arguments as to the respective merits of Olivetti versus Smith Corona typewriters, both are now hobby technologies, the rest of the world has moved on.