CA On The Noctivid (1 Viewer)

Just to add - and ask, does the person who sees CA mean that they have superior vision than one who views through the same glass does not? or is it One can view through a glass, not see CA, but it is there at a level that cannot be seen/observed.

Andy W.

I think that it is logical to postulate that if all the rays don't come to the same point of focus, you are looking at a degraded image.

Whether or not you perceive it as such is a whole different matter, and is dependent on your eyes and the signal processing circuits in your brain.

That's just my opinion, and I ain't no expert.

Back in the 1990s I had Cataract surgery and received a new lens in my eye. (I am writing about this from memory.) For a short period of time after the surgery I saw under some conditions a fine ring of color around my vision. I discussed it with my Opthamologist and he said I should expect it to disappear shortly. I believe he said my brain would not see it or something like that and he was right; it disappeared. I specifically asked him if what I saw was Chromatic Aberration and he said "exactly."

I can state categorically that I was able to see better without it. What ever happened to it, I don't know, but it is gone and it does not affect what I see today.

Seeing is believing!

Bob

Henry's finding of excessive SA in the HT was confined to the 54mm models. He tested the 42mm and found it up to snuff.

Henry has also, some few years back, photographed various versions of field geometry presentation, including the kinds that often lead to the perception of rolling ball and the absence thereof, and also both longitudinal and lateral CA, all creatively conceived, accurately carried out, and lucidly discussed.

He has made such uniquely valuable contributions here, that I don't like seeing him misunderstood and dissed. When he goes, sorry, guys, you haven't got another one. Naturally, my opinions are completely subjective, ha!

Ronh

Henry was right in his post, if I cannot see CA then I can provide no useful information to those who see it. I consider myself very fortunate not to observe it in any of my glass.

Back to night time viewing.
Andy W.

Thank you for your responses about the CA. I know this is a topic that often brings a lot of debate, and there does seem to be some confusion and different perspectives regarding CA, how it is perceived, and how it affects image quality.

I'll say this. I really only see CA when I am tracking objects against high amounts of back light. So, there are a lot of things that might be different from this situation than what is measurable in the lab:

• There may not be perfect focus on the object.
• Large amounts of broad spectrum light coming from the sky
• Object not perfectly center in frame
• Eyes not perfectly lined up with obective lenses
• Interpupillary distance set imperfectly

It is a lot harder to make repeatable measurements on the above variations, so my guess is that no one has really studied or rated the sensitivity of the above factors to observation of chromatic fringing. Maybe I am not using my binoculars correctly enough to eliminate optical aberrations, or I am expecting too much from the optical system under conditions that aren't ideal.

On the other hand, I remember seeing CA on digital prints in my earlier photography days on all sorts of lenses. Even some of the high quality zooms. Then these problems went away when I invested in some high quality prime lenses.

.. Anyways, right now a lot of my question is hypothetical. I'd love to address that. I'd love to have a bunch of alphas for a week or two for side by side comparisons or to at least get a view through them for more than a minute. It sounds like a few of you have stores that let you try and buy. Not sure if I'm going to find that in the Washington DC area though. I don't think the Leica store would be game for that--they seemed nervous to have me walk outside the store with them to look at some Rock Pigeons and Starlings.

b3rd,

Thanks for your summary, I take it the cities vendors are not used to OP going outside to try a product, afraid of someone taking off with the product.

RonH,

What is the word "dissed", I have never seen or used the word, my grandparents and parents never used it. What does it mean?

Andy W.

b3rd, post 26,
Chromatic aberration is really one of the optical errors that can not be corrected if it is part of your optical instrument/system, whether you change the IPD, a lot of light coming in etc. It is also not a laboratory phenomenon, but a real property of a particular optical system and there is nothing you can do about it if it is there. You can not ask light waves of different color to walk with exactly the same speed through glass components, since they have a tendency not to listen unless you make a proper choice of different glass types for your optical system.
Gijs van Ginkel

chill6x6 said:

At what point does CA that I don't see in Noctivids that I own impede or hamper my ability to enjoy this binocular while birding?

How many binoculars does that leave for those of us to buy/use that don't have CA that some see?

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Indeed. And more generally how much CA in the centre field is necessary to degrade the image so much that the bird cannot be identified or the image enjoyed? CA is definitely going to degrade the image but is the image still useable and enjoyable? One answer could be that there will a distance from the object being viewed at which a key diagnostic feature cannot be reliably identified or differentiated from something similar but belonging to a different species due to the CA. But you can say this characteristic is also true of magnification. At a certain distance a 7x isn't enough and you need 8x and so on. Don't lets get sidetracked here about supported or hand-held for Pete's sake. And at a certain distance binos have to step back and give way to spotting scopes.

I contend that somewhere between the two extremes of CA so bad the view makes you feel sick and a view totally lacking in CA there is a large body of binos that can be criticised from an absolutist standpoint (because they have some degree of CA) but give perfectly usable and enjoyable views of nature with no noticeable CA.

Lee

One would not expect CA in a top-class binocular as the Noctivids, but it does not destroy the image quality so that it hampers your observations. So if you do not notice it or it does not disturb you in any way, do not care and use the binocular with joy. After all we are here on BF to,(in Dutch) "om spijkers op laag water te zoeken"
(translated "to look for nails at low tide").
Gijs van Ginkel

dries1 said:

b3rd,

Thanks for your summary, I take it the cities vendors are not used to OP going outside to try a product, afraid of someone taking off with the product.

RonH,

What is the word "dissed", I have never seen or used the word, my grandparents and parents never used it. What does it mean?

Andy W.

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It means "disrespected" which is used as a verb, which I'm not at all sure it is.

I think it may be an adjective, though.

Rathaus said:

I think, as usual, you are attracted to the ‘idea’ that this phenomena is somehow measurable....and yet when challenged, you will be unable to adequately do so. Perhaps some crude measurements could be cobbled together,,,but much more will not be possible.

I’ll throw out an estimate that 90%+ of what folk on BF refer to as CA is in fact some form of defective vision.

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Where do you get your 90%+ estimate from ? If all lenses/lens systems exhibit some degree of CA (whether perceived or not by the user) then how could anyone estimate a percentage coming from either the eye lens system, binocular lens system or eyeglasses (?) Could be CA in degrees of one or more lenses mentioned.

ronh said:

Henry's finding of excessive SA in the HT was confined to the 54mm models. He tested the 42mm and found it up to snuff.

Henry has also, some few years back, photographed various versions of field geometry presentation, including the kinds that often lead to the perception of rolling ball and the absence thereof, and also both longitudinal and lateral CA, all creatively conceived, accurately carried out, and lucidly discussed.

He has made such uniquely valuable contributions here, that I don't like seeing him misunderstood and dissed. When he goes, sorry, guys, you haven't got another one. Naturally, my opinions are completely subjective, ha!

Ronh

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:t:

ronh said:

Henry's finding of excessive SA in the HT was confined to the 54mm models. He tested the 42mm and found it up to snuff.

Henry has also, some few years back, photographed various versions of field geometry presentation, including the kinds that often lead to the perception of rolling ball and the absence thereof, and also both longitudinal and lateral CA, all creatively conceived, accurately carried out, and lucidly discussed.

He has made such uniquely valuable contributions here, that I don't like seeing him misunderstood and dissed. When he goes, sorry, guys, you haven't got another one. Naturally, my opinions are completely subjective, ha!

Ronh

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I'm not misunderstanding or dissing Henry in any way, and if he says it's so then it's so. I trust him implicitly on optics.

That said, we have this conundrum where most everyone having spent time with the NV have commented on sharpness and contrast - yet we also have many reporting excessive CA. My point would be that both cannot be true, at least according to the experts, as too much CA would degrade both sharpness and contrast. So, is the NV super sharp and contrasty or does it have excessive CA, which affects the rest of the image?

james holdsworth said:

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..... So, is the NV super sharp and contrasty or does it have excessive CA, which affects the rest of the image?

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This last sentence of yours sounds like a question, James.

I do have an answer, but of course nobody will and nobody should agree, since things like perception of CA are such a subjective matter.

Anyway, my personal answer is clear: the NV is very sharp and contrasty, and it does not have excessive CA (and you are right, these two things don’t really go together). I think many of those claiming the opposite should check the correct alignment of their eyes with the exit pupils (alignment has time and again been a major factor in perceiving CA or not perceiving it).

james holdsworth said:

I'm not misunderstanding or dissing Henry in any way, and if he says it's so then it's so. I trust him implicitly on optics.

That said, we have this conundrum where most everyone having spent time with the NV have commented on sharpness and contrast - yet we also have many reporting excessive CA. My point would be that both cannot be true, at least according to the experts, as too much CA would degrade both sharpness and contrast. So, is the NV super sharp and contrasty or does it have excessive CA, which affects the rest of the image?

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My limited understanding of these things is that all binoculars represent a compromise of one sort or another - some have this characteristic more than another, but all have to compromise somewhere.

Perhaps the NV is so sharp and has such good contrast that the affects of CA are simply negated? Just a theory.

Alexis Powell said:

Sensible because those who don't see CA should be happy w/a bin w/CA since they can't see it? I would argue against that thought. Whether one sees CA or not, it still degrades the quality of the view, so all else being equal, I consider it a bad characteristic.

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This is an excellent point, but could you expand on that "all else"? I've been happy for years with 32mm Leicas in which CA can be evident around the edges of the field, and probably detectable (if not by me) even at the center. Yet the view stil seems excellent, in that "microcontrasty" way people describe.

Rathaus said:

I’ll throw out an estimate that 90%+ of what folk on BF refer to as CA is in fact some form of defective vision.

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And yet the same person (including me, and I consider myself less sensitive than many others) can see less CA in one bino than in another.

tenex said:

This is an excellent point, but could you expand on that "all else"? I've been happy for years with 32mm Leicas in which CA can be evident around the edges of the field, and probably detectable (if not by me) even at the center. Yet the view stil seems excellent, in that "microcontrasty" way people describe...

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Lack of CA doesn't make a bin good optically, or good for birding. It can fail in many other ways.

A bin w/CA that does many things very well can still have superb optics and be enjoyable to use. I've enjoyed and gotten excellent use out of many bins with a lot of CA, including the Leica 8x32 BA Ultra Trinovid and 8x42 Ultravid, and the Swarovski 8x32 EL (pre SV).

I can see CA when I want to, and (if it is moderate) can tune it out when I want to. I'm very happy to use some otherwise excellent bins that suffer from CA. Nevertheless, I don't pretend that CA isn't a detriment to optical quality, and to the extent it is possible to design bins with less CA, I'd like to see it done. Unlike many birders (it seems, based on experiences in group situations in the field), I am willing to take the trouble to observe very distant birds, at the limits of my vision, and I find that I am able to identify them accurately quite often. In those situations, I find a bin with low CA may deliver, when a bin with more CA cannot, even if CA isn't impinging on my awareness. That is one reason that my Zeiss 8x32 FL replaced my Leica 8x32 BA Ultra Trinovid as a travel bin.

adhoc said:

...What is the difference, as meant here, between "corrected away by the brain" and "hidden from awareness"...

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My apologies to experts for likely not using proper terminology, but what I mean is as follows. Anything that your eyes/brain do to remove optical flaws or receptor noise from perception is an example of hiding aspects of sensation from awareness. For example, each of our eyes has a blind spot to the side of our central vision, but generally our brain hides it from awareness, so we don't "see" it. With both eyes open, the brain can perhaps use the information from the other eye to fill in what is missing from each eye. With only one eye open, the brain can only speculate on what is missing based on surroundings and so fills in the missing bit with imagination of a sort. There is no way to correct away the missing sensory data, only hide it from awareness by making up substitute data in constructing what we perceive. However, something like distortion (e.g. pincushion) can be removed from awareness by being corrected away by the brain so as to recover an accurate-about-the-world perception. The sensory data can be re-mapped by the brain so that perception is such that the distortion has been removed. In this case, no data is missing. The re-mapped subjective mind's eye vision is complete and, in a certain sense, a more accurate rendering of the world than is the distorted projection from the optical system. I can't deny that my Swarovski 8.5x42 EL SV has a lot of AMD, but when I look through it in normal use, I see no rolling ball.

--AP

Alexis Powell said:

My apologies to experts for likely not using proper terminology, but what I mean is as follows. Anything that your eyes/brain do to remove optical flaws or receptor noise from perception is an example of hiding aspects of sensation from awareness. For example, each of our eyes has a blind spot to the side of our central vision, but generally our brain hides it from awareness, so we don't "see" it. With both eyes open, the brain can perhaps use the information from the other eye to fill in what is missing from each eye. With only one eye open, the brain can only speculate on what is missing based on surroundings and so fills in the missing bit with imagination of a sort. There is no way to correct away the missing sensory data, only hide it from awareness by making up substitute data in constructing what we perceive. However, something like distortion (e.g. pincushion) can be removed from awareness by being corrected away by the brain so as to recover an accurate-about-the-world perception. The sensory data can be re-mapped by the brain so that perception is such that the distortion has been removed. In this case, no data is missing. The re-mapped subjective mind's eye vision is complete and, in a certain sense, a more accurate rendering of the world than is the distorted projection from the optical system. I can't deny that my Swarovski 8.5x42 EL SV has a lot of AMD, but when I look through it in normal use, I see no rolling ball.

--AP

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That's a good explanation. I wish Oliver Sacks was still around to weigh in on this one. ;-) The blind spot explanation is a good example of how the brain cleans up our vision to correspond to our perceived reality better.

I've been cross-eyed since I was a kid, and have had several surgeries in my youth to correct it, however it never did quite succeed. So, even with glasses on, I have a sort of fringe double vision, that my brain has been correcting away for years. Ironically, if I can squish my binoculars together close enough, roughly 56-57mm IPD, then my eyes fuse, and I see in stereo. Voila! Binoculars can be very effective corrective lenses, and as long as one is birding, it seems utterly natural to go around looking through them...

-Bill

Alexis Powell said:

can't deny that my Swarovski 8.5x42 EL SV has a lot of AMD, but when I look through it in normal use, I see no rolling ball.
--AP

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Has a lot of what?