best low light bino 10x (1 Viewer)

Gijs van Ginkel said:

Chosun Juan, post 60,
Weeping I rest behind my computer: "only seen one SF transmission spectrum", while you could have seen two if you had looked at the WEB-site of House of Outdoor, where I have published a load of transmission spectra among others from the Zeiss SF, so still time to see more...........
Gijs van Ginkel

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Chosun Juan said:

.................
As soon as I can find your SF graph, I look forward to seeing it :t:

Chosun :gh:

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Gijs van Ginkel said:

Chosun Juan, post 82,
The WEB-site I am referring to is from House of Outdoor .......

Although the reports are in Dutch you have shown on this WEB-site that you are a very intelligent (and funny) person, so you will undoubtedly be able to understand the test tables and graphs even if they are in Dutch and Google translate can help you further if necessary.
Gijs van Ginkel

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WJC said:

ATTENTION ALL UK AND EUROPEAN OPERATIVES!

LGM as somehow infiltrated and learned our secret, AO06. He must be taken out at all cost, lest he spread AO06 across the free, and not so free, world. You are authorized to use any method at your disposal. This includes the collimator that emits parallel light rays. :cat:

.00000000007
by direction

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Chosun Juan said:

GiGi,

Even though the actual numerical gains in light transmission from HT glass seem inconsequential - 2% (when our ability in practice to detect differences in brightness is only when it reaches ~3-6%), you, like Lee, observe that somehow the difference in viewing seems rather greater than the sum of these rather incrementally improved parts. I think you are right on in your reasoning.

Light lost in transmission can manifest in all sorts of undesirable ways - some of the light "absorbed" in glass elements gets converted to heat. Other light is reflected which then must be dealt with (to greater or lesser degrees of success) by apertures, baffling etc ..... :cat:

Think of it rather simply like this:
Transmission = 92% , therefore 8% is lost = crud (reflections, refraction, absorption, stray light which degrade the view)
New Transmission (with HT glass) = 94% , therefore only 6% is now crud.

Difference in Transmission is +2% -> a (2÷92) = 2.2% increase.
Difference in Crud is -2% -> a (2÷8) = 25% reduction

That large reduction in crud is letting you see a cleaner, more vibrant, contrastier view as you have so aptly described.

I have only ever seen one transmission curve for the SF from Allbino's - and it was truly tragic - falling off a mountaintop in the blue in particular, and the deep red. Not only would this affect colour vibrancy, colour rendition neutrality, but ultimate brightness too. https://www.allbinos.com/304-binoculars_review-Carl_Zeiss_Victory_SF_10x42.html

HT glass would fix this very nicely indeed since the majority of the gains occur in the blue part of the spectrum. The need for high blue light transmission to give daytime brightness is probably not widely understood here, but the standard has been revised a few times with new models to incorporate this effect. Far from offering a 'colder' view - it will be more vibrant, brighter, more contrasting, and more neutral. It certainly has been good for the UVHD+ and the NV.

I'm sure the relationship between EP, Transmission, and even AFov could be mathematically modeled - but it's just as good in practice to know that your 6mm EP works nicely for you :t:



Chosun :gh:

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elkcub said:

Hi Alan,

Have you taken into consideration that every binocular-telescope has a field stop in front of the eyepiece that limits the angular FOV of the system and, hence, the amount of photons allowed to enter the eye? All other things equal, the ratio of the field-stop areas equals the ratio of total light entering the eyes. And the light entering the eyes, in quantity and quality, is what determines perceived brightness.

All the variables Gijs mentioned earlier are correct, but the FOV and retinal projection area are also a part of perceptual brightness determination.

Ed

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Patudo said:

A few weeks ago I tried both SF and HT 8x and 10x42 models at Birdfair, looking over the marsh in front of the optics marquee and the woodland/farmland beyond. These two were amongst the "alpha" models I most wanted to look through and fortunately there were enough display examples, presented side by side, that I was able to get a reasonable amount of time with them and switch between them, looking at birds under changing light conditions that varied from overcast to sunny.

I must admit; I am really feeling like a nitnoid now saying this, and I'm acutely conscious of never having attempted to so much as turn a screw on any of my binoculars - I just try my best to look through the damn things as often as I can. But my perception (for what it's worth) was that the HT models were a little brighter. Not by much, but I did notice it. I felt the SFs would have been more useful to me because of their very wide field of view, but if the great majority of my birding took place in poor to marginal light conditions the difference in perceived brightness would have been enough for me to choose the HT. My brother was with me and his perception was the same; and in fact I do genuinely think that if 100 birders, male and female, who had looked through them were polled, a majority would also think so. Ditto the Nikon EDG being slightly darker (which Tobias Mennle pointed out in his excellent review of an extremely good binocular).

The x54 and x56 class HT and SLC were very distinctly brighter than any of the x42s, and I very much agree with the statement that "The real contributing factor in image brightness is the size of the EXIT PUPIL and the spot presented to the receptors in the eye" . Thanks to the experts on this forum I've also become aware that perceived brightness may be affected by other factors (baffling, stray light, the shape of the transmission spectrum - thank you Gijs for pointing this out - etc) than purely "through the glass" transmission. But whatever the reasons may be, I did notice differences in brightness between those three x42 models (HT, SF, EDG). Some binoculars (specifically 8x42 SF vs 8.5x42SV.FP and 10x54 HT vs 10x56 SLC) are so close in brightness I could not say one was brighter than the other; I may well not be able to notice any difference in brightness between say the 10x42 HT and 10x42 FL (an example of which I have looked through in the past and found to be slightly, but again noticeably, brighter as well as a little sharper than the 10x40 BGAT*P* Dialyt I own). I have read a post, in the same German language forum that has Holger's comments comparing the 10x54 HT and 10x56 SLC, that summed up a blind test between an Ultravid HD and HD+ of the same configuration (I can't remember off the top of my head whether 8x42 or 10x42). The test audience (of "regular" folks) found no differences between the two. I have no trouble believing this. But as between the HT, SF and EDG, I did see differences in brightness.

ps. As an aside, I suspect (insert disclaimer re subjectivity etc) the difference in perceived brightness between HT and SF is probably mainly due to the optical train of SF having more elements - needed to achieve the very wide field of view and flat field - and maybe things like baffling, differently tweaked coatings, and possibly Schmidt-Pechan vs Abbe-Koenig prisms, than major differences in transmission. Field of view is a valuable thing to have in many situations (including peregrine-watching - I'd love to have a good long session observing Chosun's macropus birds and would gladly do it with an uncoated Binuxit with 60% transmission!) and many users probably would rather have that combination of wide field and flat field instead of a bit more brightness.

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typo said:

Ed and Gijs,

A litle while back I stumbled across an abstract from a scientific paper that might have some bearing on your discussion. It mentioned that the pupil diameter was related to the angle of the illuminated field. I don't remember all the details now, but the key message I took from it was that that at specific luminance levels, the greatest pupil response was to angles between about 5° and 40°. Most current binocular models fall into the 50° to 65° range so perhaps the difference in pupil response would usually be small or nonexistant. Unfortunately I did not bookmark the abstract.

However that paper did have a bearing on my eye examination. When I went for a routein eyetest a couple of years back, I noted that my apparent acuity had dropped from the previous examination, and was now approximately 50% worse than own measurement. The optometrist had recently refitted his examination room, including the lighting, and now did the chart test in much darker room. After some discussion he allowed me to return with a light meter and take a couple of measurements.

Optimum acuity is normally considered to be at luminance levels around 300cd/m2 and I've found that 200 to 1000cd/m2 gives me the same result. The guidance for UK eye tests is that the chart should be over 175cd/m2, and with a nonscientific meter the LCD monitor measured 180cd/m2. However the wall surrounding the monitor was 15-20cd/m2. At 6m the display was about 7° wide and a little less tall. My pupil was estimated by the optometrist at 4.25mm while viewing the chart, far wider than the usual 2.5mm acuity optimum and would completely explain why the optometrist's measurement was 50% worse than I might have expected.

The consequence for my correction has had it's positives and negatives. By my estimates, my daylight acuity has dropped by 5 arcseconds, but low light reading improved by about 30 arcseconds. I guess that's a useful result, but I still switch to my old glasses for critical viewing.

My experience is that angle of view does make a significant difference to pupil diameter, but may not impact on binocular choice.

David

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ailevin said:

Ed,

It seems that you are assuming that the field stop of an eyepiece with narrower field of view must be blocking the clear aperture at the objective. This need not, and if fact should not be the case.

Alan

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Field Stop

The field stop is a ring inside the barrel of an eyepiece that defines the edge of the field of view. In most eyepieces the field stop is not the inside of the barrel but a designer introduced ring inside the barrel, this is introduced to sharply delineate the edge of field of view and to prevent a gradual drop off in quality of view. In some reviews, the reviewers will state that the field stop in not properly placed; this usually means that the edge of the field of view is ‘mushy’ which detracts from the viewing pleasure. The field stop limits the Apparent Field of View (AFOV) and True Field of View (TFOV) of an eyepiece.

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[email protected] said:

That is the kind of post I like! No theories why it can't be true or there is no way you can see the difference because of this or that about the eye brain communication. Just a simple side by side comparison of the Zeiss HT and the Zeiss SF with your eyes. Then after comparing them you just say Heh the HT is a little brighter. I especially like it when they agree with me.:-O The prisms are a little bigger and more efficient and the glass is a little more transparent and transmitts better on the HT so it is a little brighter. This ain't rocket science. If you want a low light binocular get the Zeiss 10x54 HT if you are over 50 and if you are under 50 get the 8x54 HT. Easy peasy!

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WJC said:

Well, this has turned into a greatly enlightening thread for me, if no one else. We have beaten this dead horse enough to cause the most enlightened among us to come forth with something more important to the subject than the perceptions of those seemingly so eager to ignore our many physiological differences.

Cowardly, I must first say that the position I have taken was based on conversations with those infinitely more qualified to comment on the subject than myself. It rang true to my level of understanding. So, I felt confident in passing along what presented itself to be something more than opinions of the inexperienced.

But, looking forward to using some of the words here in a future, updated BINOCULARS:, I would like to boil down some comments to aid my understanding. At this point, I will ask ED and Gijs to comment. You both know why I come here. So, there is no need to worry about being politically correct or soft-shoeing.

So, I will restate my comment and ask that each of you comment as to whether or not the statement is true—I am still unconvinced; convince me:

“In comparing two binoculars on the same magnification, the same aperture, and similar quality, relative to image BRIGHTNESS, the average observer can—overlooking wavelength, brightness of the target, background illumination, photopic and scotopic considerations, vacillating physiological perceptions, and other differing criteria—determine a difference in the instruments.”

I see this as a far-from-practicality project. However, the nitnoids need love too and if this question has a definitive answer I would like to know it, so as to give me a new baseline for additional research.

Ed Yes ___1/2___ No __1/2___
Gijs Yes ______ No _____

Bill

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elkcub said:

Hey Bill,

I do apologize for putting you last, but it simply takes more skill to answer a simple question simply. Thanks for reducing the options to two, which has the benefit of giving me the opportunity to provide fully one bit of information. ("Never provide two when one will do," said my old buddy, Tom.)

The quandry is that you asked about an "average observer," whom I've never met. All observers are unique (as you keep saying). So, I'm like the poor peasant being kicked by a soldier and asked "Wat do you feed your chickens while the Russian Army starves? To which he answers: "So, ... I give them some rubles and they buy what they want!?" Similarly, I give 'em information and they buy what they want.

Are we crystal, buddy? :smoke:

Ed

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ailevin said:

Ed,

We may be having trouble communicating and I apologize. I think we are in agreement in several areas. I agree with you the the eyepiece field stop can limit the field of view, which is to say the variety of angles at which you can look through the optical system.

My point was that the field stop does not necessarily decrease the light throughput while looking on axis, or over large portions of the field of view. This is because the eyepiece field stop is usually quite close to the focal plane and the diameter of the field stop is tens of millimeters in diameter while the scale of the image formed at the focal plane can be rather small. For example for a typical 50mm binocular (perhaps F5?) will have an image scale of something like 14 arc minutes per millimeter. So an image of the full moon would occupy 2mm at the focal plane. What difference would a larger or smaller field stop make in that case? When you consider the combined objective and eyepiece system, your eye is presented with an exit pupil of a certain size and the field of view is only a statement of how you can "point your eye" through the optical system. But your eye will always see a maximum exit pupil of (clear aperture)/magnification.

I am also willing to accept that my ideas about exit pupil, image formation, and how optical systems work are just wrong. Can you explain to me how much brighter the image should be with increasing field of view? I can easily test it by changing eyepieces at the same magnification in the same telescope. As I mentioned earlier these eyepieces have similar transmission, and identical focal length, so field of view will be the only variable.

Alan

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