Being a rank amateur, I get confused by the terminology. I don´t know where the dividing lines are between resolution, clarity, sharpness, contrast, brightness, etc. etc., and I don´t have the patience to read through helpful posts by experts who kindly try to explain these to the likes of me. Such experts probably become frustrated with my ignorance, in which I imagine all these concepts to be like partially overlapping Venn Diagrams, with fuzzy lines where they intersect. So I lump them all together and call them "resolution" (well I would if I ever used the word in real life, to mean something other than a promise to improve as a person in the New Year...). I can honestly say, using layman´s terminology, that comparing an 8x compact of the highest quality to an 8x SE, or 8.5x SV, and viewing over long distances (for example distant seabirds or over a marsh), I can discern far more detail with the larger binos than with the compacts. By this I mean I can identify birds at a greater distance, and see more detail of their plumage, etc. I don´t know if this is because of brightness, or whatever, but it´s there to my eyes. I can´t swear that other people will or won´t agree, using the same binoculars in similar circumstances. I get the same effect with similar magnifications when comparing an ED50 to an 80/82mm Nikon or Swaro scope. This doesn´t mean that compacts or ED50 are not useful, they obviously are, and for obvious reasons. But when viewing over longer distances, when I can put up with the extra weight and bulk, I prefer the larger objective optics of similar mag., as I can "see" more, in similar conditions. As Dennis intimated, otherwise we´d all use compact binos/scopes and nothing else.
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Can a small bino really deliver? (2 Viewers)
- Thread starter Super Dave
- Start date
This resolution thing for different bins is something that's be bothering me.
If I look at fine back and white detail like news print (or a test chart) under good light then the cost of the bin or objective size (within reason) appears to me to make only a modest difference to what you can see. (I think that ties in with the test data I've seen) Yet they can be miles apart when looking real things like birds.
I've tried to understand a little of what Prof Edz, Henry and others have said on the subject of resolution, but a point I've not seen, or more likely missed, is the effect of contrast. On a resolution chart, the test is to resolve black on white or no reflected light vs. reflected light. To my simple mind the higher the ratio, the easier it is to distinguish. Therefore bigger objectives collect more reflected light so it is easier to distinguish the detail... particularly in low light conditions. I don't think the resolution tests I've read about are sensitive to this, but please correct me if I'm wrong. I would call that higher contrast
Then it gets a bit more complicated. For instance if I compare my 7x26 reverse poros against my non phase coated 10x42s for instance, they are similar brightness. The 10x easily out resolves the 7x on a chart test in good light as it should, but because the 10x lacks contrast the 7x out resolves the 10x in poor light. That is another different contrast effect as well isn't it?
Then it gets more confusing. It seems pretty clear to me that they also play tricks with the colour spectrum. I guess due to coating design the 7x has a better resolution score when looking at blue on yellow or blue on white than black on white. There are other differences when resolving one colour on another when comparing the simple coated 10x with the complex coated 7x. What ever they've done the result is that the contrast between certain colours is enhanced on the 7x, so even in good light I can see more detail on birds etc. with the 7x than the 10x. That is a different kind of contrast. Colour contrast?
So I think it means as the guys above have suggested, if every thing else is equal in the design, the big objective will generally win out, but not because it should have a higher bench test resolving power, but because the contrast is higher. It also means it is also possible to see more detail in practice with a well designed small binocular than a poorly designed large one, even if the bench test resolutions are the same.
In practice, perhaps stating the obvious, it means that test bench resolution, and big objectives are only part of the story of why expensive expensive is better. There are a number of elements relating to contrast that I poorly understand and I'm struggling to describe. I guess that goes for many others too.
Any help in making sense of this appreciated.
David
If I look at fine back and white detail like news print (or a test chart) under good light then the cost of the bin or objective size (within reason) appears to me to make only a modest difference to what you can see. (I think that ties in with the test data I've seen) Yet they can be miles apart when looking real things like birds.
I've tried to understand a little of what Prof Edz, Henry and others have said on the subject of resolution, but a point I've not seen, or more likely missed, is the effect of contrast. On a resolution chart, the test is to resolve black on white or no reflected light vs. reflected light. To my simple mind the higher the ratio, the easier it is to distinguish. Therefore bigger objectives collect more reflected light so it is easier to distinguish the detail... particularly in low light conditions. I don't think the resolution tests I've read about are sensitive to this, but please correct me if I'm wrong. I would call that higher contrast
Then it gets a bit more complicated. For instance if I compare my 7x26 reverse poros against my non phase coated 10x42s for instance, they are similar brightness. The 10x easily out resolves the 7x on a chart test in good light as it should, but because the 10x lacks contrast the 7x out resolves the 10x in poor light. That is another different contrast effect as well isn't it?
Then it gets more confusing. It seems pretty clear to me that they also play tricks with the colour spectrum. I guess due to coating design the 7x has a better resolution score when looking at blue on yellow or blue on white than black on white. There are other differences when resolving one colour on another when comparing the simple coated 10x with the complex coated 7x. What ever they've done the result is that the contrast between certain colours is enhanced on the 7x, so even in good light I can see more detail on birds etc. with the 7x than the 10x. That is a different kind of contrast. Colour contrast?
So I think it means as the guys above have suggested, if every thing else is equal in the design, the big objective will generally win out, but not because it should have a higher bench test resolving power, but because the contrast is higher. It also means it is also possible to see more detail in practice with a well designed small binocular than a poorly designed large one, even if the bench test resolutions are the same.
In practice, perhaps stating the obvious, it means that test bench resolution, and big objectives are only part of the story of why expensive expensive is better. There are a number of elements relating to contrast that I poorly understand and I'm struggling to describe. I guess that goes for many others too.
Any help in making sense of this appreciated.
David
elkcub
Silicon Valley, California
Although it has been argued for years which discipline owns the word "resolution," the truth is that on the optical side of the exit pupil the word has one definition, and on the observer side it has another. Optical resolution can be measured on a bench with no observer present. Measuring visual resolution (also known as 'visual acuity') requires an observer. It is essentially the same thing as measuring one's eyesight with or without spectacles, except, in this case, we measure eyesight with or without the help of a telescope or binocular.
Visual resolution is actually a broad term encompassing several sub-categories that are defined by specific viewing tasks, the so-called acuities. Distinguishing separations between line pairs is called grating acuity. Distinguishing line offsets is call vernier acuity. Distinguishing relative differences in distance (using both eyes) is called depth or stereo acuity. There are, as well, several other visual acuities concerned with our ability to make fine color distinctions. All of these are influenced by the idiosyncrasies or the viewer and the ambient viewing conditions.
With the exception of grating acuity, however, very little is known about the other acuities impacted by binoculars. Still, logic suggests that our perception of the overall visual scene (i.e., the 'view') must be a composite of all these effects working together. The word "sharpness," is generally considered the psychological dimension that describes the binoculars' net ability to accentuate differences in perceived objects within the view.
I hope this hasn't confused matters even more.
Ed
PS. Of course, I could be wrong.
Visual resolution is actually a broad term encompassing several sub-categories that are defined by specific viewing tasks, the so-called acuities. Distinguishing separations between line pairs is called grating acuity. Distinguishing line offsets is call vernier acuity. Distinguishing relative differences in distance (using both eyes) is called depth or stereo acuity. There are, as well, several other visual acuities concerned with our ability to make fine color distinctions. All of these are influenced by the idiosyncrasies or the viewer and the ambient viewing conditions.
With the exception of grating acuity, however, very little is known about the other acuities impacted by binoculars. Still, logic suggests that our perception of the overall visual scene (i.e., the 'view') must be a composite of all these effects working together. The word "sharpness," is generally considered the psychological dimension that describes the binoculars' net ability to accentuate differences in perceived objects within the view.
I hope this hasn't confused matters even more.
Ed
PS. Of course, I could be wrong.
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Typo
I think we are trying to over simplify what makes us like the view through any one binocular better. Resolution is just one part of the picture. Contrast which usually is associated with high quality coatings is another aspect that helps us see detail. Brightness improves the picture also as does ED glass which eliminates CA and makes the view sharper. The list goes on and on. All I know is I can not see detail as well at distance with a compact as I can with a full size binocular and I don't care what the optical theory is. I think there could be alot of other underlying factors that we have not considered besides resolution. There are some advantages to those big objective lenses that we have not considered.
Henry Link(Mr Optics)
Ok, Henry. So in theory a 8x32 Zeiss FL will have the same resolution as a bigger objective binocular and in the daytime it will also be as bright. Correct?
So answer me this question why would you even have a Zeiss 8x56 FL and extoll the virtues of it's optical excellence. Why would you carry such a heavy behemoth instead of a 32mm binocular if there were not some optical advantage. You have said again and again that optics are everything to you so that 56mm aperture must have SOME advantage over a 32mm. What do you like about the Zeiss 8x56 FL that a 32mm doesn't have?
mayoayo
Well-known member
Well,In a very non scientific way this can be compared with the small sensor in a compact 6mp camera or the larger 6mp sensor of a Digital reflex.......If the Exit pupil(the projected image) is larger ,has to have more detail..or at least offers the brain the possibility to look for it easily in the same amount of time....
Dennis,
As I recall it (and you have probably read yourself) Henry's rationale for preferring the 56 over the 32 (or the 42) centers on two things. Firstly because of the eye pupil so often being smaller than the binoculars' exit pupil, with the larger binocular one ends up utilizing the low-aberration central portion of the objective, significantly reducing optical aberrations and giving a cleaner image closer to "diffraction limited." Secondly, the larger binocular, especially when stopped down by the eye's pupil, is a longer focal-length system which has less longitudinal CA than a smaller binocular of otherwise identical quality. Then there would be the benefits you get when light levels are low and your pupils are dilated.
As to the question of visual resolution attainable with small binoculars, I'll quote my own test from a few years back, where grating acuity was measured using the combination of tested binoculars and my eyes, visus ca. 1.5.
"I measured the resolution of tripod-mounted binoculars at ten meters distance, viewing evenly illuminated test targets both with my eyes only and with a 3x booster. The Opticron with its largest objectives had the best resolution: I could resolve 2.2-2.5 line-pairs/mm without the booster and 3.6-4.5 lp/mm with the booster. Nikon’s score was 2.2 lp/mm unboosted and 3.6 lp/mm boosted, while Leica scored 2.0-2.2lp/mm unboosted and 3.2-3.6lp/mm boosted. Unboosted, the Zeiss and the Swarovski had the same result as the Leica, and boosted they gave 2.8-3.2 lp/mm. Variation in the results for a single binocular comes from different resolution results for the two sides of the binocular. When viewing unboosted with both eyes, I always resolved as well as with the better side alone. For the sake of comparison, for 8x binoculars with 42mm objectives my best results in the past have been easy resolution of 2.5 lp/mm unboosted and 5.7 lp/mm boosted."
It needs to be commented also, that among the small binoculars in this test group there were two (the Nikon and the Leica Ultravid) that happened to have exceedingly low levels of total aberrations in at least one half of the binocular. Despite this, I could not resolve quite as small detail through them than through "full-size" 8x binoculars.
It has been experiences like the one quoted above that have led me in the past to hypothesize that in order to "allow" my eyes to resolve all they can from an image binocular delivers, the said binocular must have resolution about twice as good as my eyes. I cannot claim to understand everything that is going here, but a 2.5mm exit pupil even with essentially perfect image quality just does not seem to give as much detail to my eyes as they could benefit from.
Kimmo
As I recall it (and you have probably read yourself) Henry's rationale for preferring the 56 over the 32 (or the 42) centers on two things. Firstly because of the eye pupil so often being smaller than the binoculars' exit pupil, with the larger binocular one ends up utilizing the low-aberration central portion of the objective, significantly reducing optical aberrations and giving a cleaner image closer to "diffraction limited." Secondly, the larger binocular, especially when stopped down by the eye's pupil, is a longer focal-length system which has less longitudinal CA than a smaller binocular of otherwise identical quality. Then there would be the benefits you get when light levels are low and your pupils are dilated.
As to the question of visual resolution attainable with small binoculars, I'll quote my own test from a few years back, where grating acuity was measured using the combination of tested binoculars and my eyes, visus ca. 1.5.
"I measured the resolution of tripod-mounted binoculars at ten meters distance, viewing evenly illuminated test targets both with my eyes only and with a 3x booster. The Opticron with its largest objectives had the best resolution: I could resolve 2.2-2.5 line-pairs/mm without the booster and 3.6-4.5 lp/mm with the booster. Nikon’s score was 2.2 lp/mm unboosted and 3.6 lp/mm boosted, while Leica scored 2.0-2.2lp/mm unboosted and 3.2-3.6lp/mm boosted. Unboosted, the Zeiss and the Swarovski had the same result as the Leica, and boosted they gave 2.8-3.2 lp/mm. Variation in the results for a single binocular comes from different resolution results for the two sides of the binocular. When viewing unboosted with both eyes, I always resolved as well as with the better side alone. For the sake of comparison, for 8x binoculars with 42mm objectives my best results in the past have been easy resolution of 2.5 lp/mm unboosted and 5.7 lp/mm boosted."
It needs to be commented also, that among the small binoculars in this test group there were two (the Nikon and the Leica Ultravid) that happened to have exceedingly low levels of total aberrations in at least one half of the binocular. Despite this, I could not resolve quite as small detail through them than through "full-size" 8x binoculars.
It has been experiences like the one quoted above that have led me in the past to hypothesize that in order to "allow" my eyes to resolve all they can from an image binocular delivers, the said binocular must have resolution about twice as good as my eyes. I cannot claim to understand everything that is going here, but a 2.5mm exit pupil even with essentially perfect image quality just does not seem to give as much detail to my eyes as they could benefit from.
Kimmo
Thanks Ed and Dennis,
Apologies for my clumsy terminology. Yes I see that acuity is part of what I was trying to describe. However what I was trying to get at was there appear to me to be a number of other parameters I loosely described as contrast which affect acuity. I guess these could be measured, or in practical terms better articulated. When I compared a popular Chinese ED pair with low CA to a couple of mid price european pairs with higher CA, I could probably see more detail over a greater area of the view with the low CA bins. However it was easier for me to spot important detail with the european ones. Not the least because the blacks seemed blacker and the colours richer. Just a small part of a complex number of reasons why a good 'little 'un' can be better than a average 'big 'un'. Of course an expensive big 'un is going to cover more bases. Just wish I understood this 'contrast' thing better. I guess 'sharpness' will have to do for now, but with limited experience I like European and some Japanese 'sharpness' better than the Chinese ED 'sharpness', at least in the reasonable price range.
Regards,
David
Apologies for my clumsy terminology. Yes I see that acuity is part of what I was trying to describe. However what I was trying to get at was there appear to me to be a number of other parameters I loosely described as contrast which affect acuity. I guess these could be measured, or in practical terms better articulated. When I compared a popular Chinese ED pair with low CA to a couple of mid price european pairs with higher CA, I could probably see more detail over a greater area of the view with the low CA bins. However it was easier for me to spot important detail with the european ones. Not the least because the blacks seemed blacker and the colours richer. Just a small part of a complex number of reasons why a good 'little 'un' can be better than a average 'big 'un'. Of course an expensive big 'un is going to cover more bases. Just wish I understood this 'contrast' thing better. I guess 'sharpness' will have to do for now, but with limited experience I like European and some Japanese 'sharpness' better than the Chinese ED 'sharpness', at least in the reasonable price range.
Regards,
David
Good idea and explanation. Good to hear from you again Mayoayo!
No expert here, but I don't think that's the way it works. The small physical size if the compact camera chip means the number of photon's captured/pixel is small and the signal to noise ratio high. The big sensors can capture vastly more photons, giving a bigger dynamic range.... higher contrast.... or better high iso number performance. Not higher resolution.
6mp on both cameras means the resolution is the same (if the lens quality is equal)
But then I might be mistaken.
David
henry link
Well-known member
Dennis,
As Kimmo explained what I like about the 8x56 is the center of the objective. Unfortunately I had to buy the rest of the objective and a heavy binocular to get it. Large exit pupils have a couple of other advantages in bright light. There is very little off axis vignetting so the field is fully illuminated all the way to the edge and glare is minimized because reflections at the edge of the objective fall on the iris of the eye rather than entering the pupil. The image is very clean, bright and relaxing to look at, but there are no tiny bits or specks visible in the 8x56 in daylight that aren't visible in the same optics stopped down to 32mm or even 20mm.
An easy controlled test for this is to simply stop down one side to 20mm and examine a resolution chart in daylight (on a tripod). That eliminates the variables associated with different binocular optics and goes directly to the question of whether aperture alone limits the detail visible at 8x. Today I did that and found the true resolution of the stopped down 20mm side to be about 7 arcsec with the magnification boosted to 24x. That's not so wonderful, but at 8x I could only see down to about 13 arcsec with the binoculars tripod mounted and hand held could only get glimpses of 15-16 arcsec. I got exactly the same result with the full aperture side at 8x.
Around sunset yesterday I did the same test in relatively low light with interesting results I've seen before. With my eye open to about 4mm I found the image to be dimmer, but sharper through the 20mm side. That result is caused by the increasing aberrations of the eye as it dilates. Most people have higher acuity at 2.5mm dilation compared to 4mm. So, even in subdued light I saw no extra resolution in the full aperture side. Of course at some point the image will become too dim through the 20mm side, but no one ever claimed an 8x20 is a good owling glass.
I agree totally with what you are saying. So in essence a larger objective binocular does resolve better than a smaller objective binocular. I also feel a larger objective binocular is brighter than a smaller objective binocular even though the smaller objective binocular in theory is sending all the light that the eye can possibly receive to it for the same reason. The larger objective binocular is using the center portion of the lens which is free of aberrations to capture the light whereas in the smaller objective there is some vignetting along the outer circumference of the objective which reduces the light captured by the objective.
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Typo
I would bet contrast is the reason you could spot important detail better with the European binoculars. I have noticed these differences when comparing Chinese binoculars to say a high quality Japanese or European binocular. The Chinese binoculars although they have ED glass and are quite CA free do not have the contrast of the Japanese or European binocular. Contrast is largely achieved by coatings which are expensive to do correctly. I believe Swarovski's have 25 to 30 microthin layers of coating applied to their lenses which costs alot and I don't think the less expensive Chinese binoculars have these quality coatings. Contrast is bringing out thoses details for you.
So there are really alot of optical advantages to a larger objective than just greater light gathering power. Just the fact that the image is clean, bright and relaxing makes a bigger objective preferable over a smaller one. Also, I feel since you are using the center of the objective in a bigger binocular there is less chance for optical abberations in the image which would help you see detail in the image better. By the way don't you mean people have higher acuity at 4mm dilation compared to 2.5mm?
elkcub
Silicon Valley, California
Dennis,
Without wishing to speak for Henry, people have better grating acuity at 2.5 mm pupil size than at 4 mm. Basically, the human eye becomes diffraction limited when the pupil is too small, i.e., <1 mm, and aberration limited when it becomes too large, i.e., > 3 mm. Depending on the subject's state of myopia/presbyopia, target pattern and light source, optimum acuity lies between 2-3 mm. Some studies have reported optimum vision for pupil diameters as small as 1.5 mm. Probably 2.5 mm is a good compromise, — which, of course, happens to be the EP of 8x20 and 10x25 pocket binoculars. No doubt a coincidence.
Of course, that fact doesn't detract from anything Henry said about his reasons for lugging around large (huge) binoculars. Image quality improves with fewer optical aberrations.
Ed
Without wishing to speak for Henry, people have better grating acuity at 2.5 mm pupil size than at 4 mm. Basically, the human eye becomes diffraction limited when the pupil is too small, i.e., <1 mm, and aberration limited when it becomes too large, i.e., > 3 mm. Depending on the subject's state of myopia/presbyopia, target pattern and light source, optimum acuity lies between 2-3 mm. Some studies have reported optimum vision for pupil diameters as small as 1.5 mm. Probably 2.5 mm is a good compromise, — which, of course, happens to be the EP of 8x20 and 10x25 pocket binoculars. No doubt a coincidence.
Of course, that fact doesn't detract from anything Henry said about his reasons for lugging around large (huge) binoculars. Image quality improves with fewer optical aberrations.
Ed
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Dennis,
Without wishing to speak for Henry, people have better grating acuity at 2.5 mm pupil size than at 4 mm. Basically, the human eye becomes diffraction limited when the pupil is too small, i.e., <1 mm, and aberration limited when it becomes too large, i.e., > 3 mm. Depending on the subjects state of myopia/presbyopia, target pattern and light source, optimum acuity lies between 2-3 mm. Some studies have reported it for pupil diameters as small as 1.5 mm. Probably 2.5 mm is a good compromise, — which, of course, happens to be the EP of 8x20 and 10x25 pocket binoculars. Probably a coincidence.
Of course, that fact doesn't detract from anything Henry said about his reasons for lugging around large (huge) binoculars. Image quality improves with fewer optical aberrations.
Ed
Yes. I know alot of birders that lug around Swarovski 10x50's and they do provide a darn good view but they are heavy.
This is one of the best discussions on BF for some time.....interesting, sometimes enlightening and most entertaining. The numerous mentions about coatings brings up several questions I've had for a while. First, I'm assuming the term "FMC" doesn't always mean the same thing....that is, I assume the "receipes" for the FMC formulae are proprietary (developed by the mfrs in their own labs) and could be quite different, both in materials used (MgFl, ZrO and other such arcane substances) and in number and thicknesses of coats and in what order they're applied. Some seem better than others, and it also seems that to achieve a desired effect (other than totally neutral), i.e., "warmth", this process could be "fine tuned". This mentioned, because on some other threads, there've been comments (grousing, if u will) that the FL's present "too cold a view". I have a couple FL's, and they seem to be dead on to me....makes me wonder if the other binos compared to were "enhanced".....
Anyway, back to the central point of this thread, i.e., compacts. Can a little one deliver the visual impact of a big one? Well, yes, with caveats. Only the 7x26 Elite, of all the ones I've tried, do, I think because of 1) larger obj - 26 vs 20, which translates to 2) larger exit pupil - brighter & easier to use 3) slightly better DOF and 4) easier to hold, if you have big mitts like me, which translates into a steadier view. (I'm sure Dennis, after reading this, is hurling rocks, flaming tree trunks and slinging arrows at his viewing screen, but that's OK.)
I've got some other observations on this, but am tired of typing, so may post later....don't hold yer collective breaths, tho'....
Anyway, back to the central point of this thread, i.e., compacts. Can a little one deliver the visual impact of a big one? Well, yes, with caveats. Only the 7x26 Elite, of all the ones I've tried, do, I think because of 1) larger obj - 26 vs 20, which translates to 2) larger exit pupil - brighter & easier to use 3) slightly better DOF and 4) easier to hold, if you have big mitts like me, which translates into a steadier view. (I'm sure Dennis, after reading this, is hurling rocks, flaming tree trunks and slinging arrows at his viewing screen, but that's OK.)
I've got some other observations on this, but am tired of typing, so may post later....don't hold yer collective breaths, tho'....
John Dracon
John Dracon
Agree with ND Hunter. The little Yosemite does deliver. There is another smaller binocular, however, which rarely gets mentioned on this website for its superior optics. Reason? It was discontinued by Nikon many years ago. It never caught on. Too chunky to be a miniature, yet undersized, it was an inverted porro with what Nikon called asperical lens. And also very expensve. Not waterproof with a so-so FOV, it featured a smooth rubber covering in gray? and fold down rubber eye cups allowing full field with eye glasses. And the diopter had a lock system similar to the Nikon LXs. It was made in two powers: 8x23 and 10x25. It was called the Diplomat. Whenever I found one I snapped it up, passing it on to friends who wouldn't use anything else.
But I never liked its ergonomics other than the focusing knob. I had to put non skid in strategic places to hold it securely - too slippery. It was too large for a front pocket and placed my large fingers in an awkward position.
But with all the negatives said, its view, particularly half the field, is simply superior to any binocular I have including the 8x32 SE and 8x32 Fl. The resolution begins to what I call thin out at the edges, but the center is razor sharp with vivid colors unlike anything
I have ever used. I have never subjected the Diplomats to the magnification tests like Mr. Link and often wondered what their resolution limit is. Better View Desired at one time listed them as a reference standard.
Wonder how many folks on BF use them and would care to comment? John
But I never liked its ergonomics other than the focusing knob. I had to put non skid in strategic places to hold it securely - too slippery. It was too large for a front pocket and placed my large fingers in an awkward position.
But with all the negatives said, its view, particularly half the field, is simply superior to any binocular I have including the 8x32 SE and 8x32 Fl. The resolution begins to what I call thin out at the edges, but the center is razor sharp with vivid colors unlike anything
I have ever used. I have never subjected the Diplomats to the magnification tests like Mr. Link and often wondered what their resolution limit is. Better View Desired at one time listed them as a reference standard.
Wonder how many folks on BF use them and would care to comment? John
