Interesting Lee. I hate Reynaud's, as you know it can be a real drag. I think with these I would keep them in a close in pocket so they stay warm; would help with fogging as well. One thing that is definitely nice about the little Uvid's is they do pretty well with gloves.
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Roger Vine's thoughts on the 7x21 Curio? (1 Viewer)
- Thread starter John A Roberts
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Gijs van Ginkel
Well-known member
Swedpat, post 17,
The exit pupil as a tunnel is not correct. The exit pupil functions as a fixed diaphragm with dimensions governed by the properties of the binocular.
Perhaps it is best to compare it with a photographic lens with different diaphragms and there also you do not describe these diaphragms as a tunnel phenomenon.. The exit pupil is than a fixed diaphragm for a given binocular.
Gijs van Ginkel
The exit pupil as a tunnel is not correct. The exit pupil functions as a fixed diaphragm with dimensions governed by the properties of the binocular.
Perhaps it is best to compare it with a photographic lens with different diaphragms and there also you do not describe these diaphragms as a tunnel phenomenon.. The exit pupil is than a fixed diaphragm for a given binocular.
Gijs van Ginkel
Gijs,
These terms is a bit above my understanding...
The exit pupil is simply the objective lens decreased with the magnification, and a function of the fact that what you gain in increased image scale you lose in pupil.
Therefore every optical instrument with same exit pupil theoretically provides the same brightness. And the naked eye is a 1x variable aperture from 2-8mm depending on the genetics and age.
Therefore if naked eye at a certain situation is 5mm pupil, a 5x25, 10x50 and 20x100 give the very same brightness(if we for exclude the small light loss in the instruments).
It's the same as if you spread 10000 lumen across 10 square meters or 1000 lumen across 1 square meter. In both cases the light intensity will be 1000 lux.
I can't see why optical system would work in another way. The optical law has to be the same.
These terms is a bit above my understanding...
The exit pupil is simply the objective lens decreased with the magnification, and a function of the fact that what you gain in increased image scale you lose in pupil.
Therefore every optical instrument with same exit pupil theoretically provides the same brightness. And the naked eye is a 1x variable aperture from 2-8mm depending on the genetics and age.
Therefore if naked eye at a certain situation is 5mm pupil, a 5x25, 10x50 and 20x100 give the very same brightness(if we for exclude the small light loss in the instruments).
It's the same as if you spread 10000 lumen across 10 square meters or 1000 lumen across 1 square meter. In both cases the light intensity will be 1000 lux.
I can't see why optical system would work in another way. The optical law has to be the same.
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Gijs van Ginkel
Well-known member
Swedpat, post 23, I will try to explain:
The exit pupil is defined for example for a 10x50 binocular as 50 :10 = 5mm. For an 8x32 binocular it is 32:8= 4 mm.
In "the old days"a photographer had a camera with a lens that had a scale with diaphragm numbers ranging for example from 4 to 5,6 to 8 etc. where 4 stood for larger = larger opening than 5,6 etc. The photographer could play with the amount of light entering the camera by choice of a large diaphragm (large means a small number here) so a lot of light could enter. But he/she could also limit that by choice of shutter time = the period in which light could enter the camera.
If we now go back to binoculars again: a binocular receives a continuus flow of light which is channelled through the optical system in the binocular to the eyepiece and leaving it through the exit pupil = the "diaphragm '" value =exit pupil size , a fixed value for a binocular. Light leaving the binocular is confronted with its "particular diaphragm" which is 5 mm for a 10x50 binocular and 4 mm for an 8x32 binocular. That value does not change when you use the binocular and it is a characteritstic property of that binocular. Apart from light losses in the optical system (absorption, reflection) it has nothing to do with an exit pupil as a tunnel. I hope that this clarifies it a bit.
Gijs van Ginkel
The exit pupil is defined for example for a 10x50 binocular as 50 :10 = 5mm. For an 8x32 binocular it is 32:8= 4 mm.
In "the old days"a photographer had a camera with a lens that had a scale with diaphragm numbers ranging for example from 4 to 5,6 to 8 etc. where 4 stood for larger = larger opening than 5,6 etc. The photographer could play with the amount of light entering the camera by choice of a large diaphragm (large means a small number here) so a lot of light could enter. But he/she could also limit that by choice of shutter time = the period in which light could enter the camera.
If we now go back to binoculars again: a binocular receives a continuus flow of light which is channelled through the optical system in the binocular to the eyepiece and leaving it through the exit pupil = the "diaphragm '" value =exit pupil size , a fixed value for a binocular. Light leaving the binocular is confronted with its "particular diaphragm" which is 5 mm for a 10x50 binocular and 4 mm for an 8x32 binocular. That value does not change when you use the binocular and it is a characteritstic property of that binocular. Apart from light losses in the optical system (absorption, reflection) it has nothing to do with an exit pupil as a tunnel. I hope that this clarifies it a bit.
Gijs van Ginkel
Gijs,
To be honest it's a bit too "academic" language for me. I am interested to know how you mean we should calculate brightness.
I think we are agreed about that it's a fact that:
1: increase of aperture at a given magnification = higher brightness.
2 : increase of magnification at a given aperture = lower brightness.
If the relative brightness index, which is an established value for describing brightness, does not show the truth, how can we apply the calculation of brightness according to "diaphragm"?
To be honest it's a bit too "academic" language for me. I am interested to know how you mean we should calculate brightness.
I think we are agreed about that it's a fact that:
1: increase of aperture at a given magnification = higher brightness.
2 : increase of magnification at a given aperture = lower brightness.
If the relative brightness index, which is an established value for describing brightness, does not show the truth, how can we apply the calculation of brightness according to "diaphragm"?
Gijs van Ginkel
Well-known member
Swedpat, post 25,
Brightness is the sum of the amount of light and the color distribution of that light and how it is judget by our eyes/brain.. Blue light is judged by our eyes as brighter than red light.
For binoculars brightness is determined by the amount of light coming out of the binocular (exit pupil plus transmitted light) and the color distribution of that light (transmission spectrum).
I have made an overview of published literature for that matter entitled "Color vision, brightness, resolution and contrast in binocular images" which is published on the WEB-site of House of Outdoor, that may help I hope.
Gijs van Ginkel
Brightness is the sum of the amount of light and the color distribution of that light and how it is judget by our eyes/brain.. Blue light is judged by our eyes as brighter than red light.
For binoculars brightness is determined by the amount of light coming out of the binocular (exit pupil plus transmitted light) and the color distribution of that light (transmission spectrum).
I have made an overview of published literature for that matter entitled "Color vision, brightness, resolution and contrast in binocular images" which is published on the WEB-site of House of Outdoor, that may help I hope.
Gijs van Ginkel
dorubird
The unskilled mechanic blames his tools!
At same optical quality, with 10x50 you can reach the same brightness as 6x30 but with higher resolution (when the distance to the target does not change). When the light decreases this resolution surplus can be translated in greater perceive of information in same low light conditions. We can call that a kind of perception of "brightness"/ information (we see in a dark more details). In the same twilight situatio with 10x50 bino you can identify, for example, what kind of duck it is on lake, while with the 6x30 binoculars you notice that it is only a duck without identifying the species. The bigger aperture gives you the ability to use higher powers/resolution but with same exit pupils. In less scientific terms we can say that the 10x50 are "brighter" in same low light situation than 6x30 because perceive more information, even if it is only a matter of perception resolution (practically we see in a dark more details with 10x50 than 6x30).
So back to the thread, assuming both bino have relatively the same optical quality, practically in a dark we will see more detail with VP 8x25 than Curio 7x21 under the same conditions: same distance to the target, same low light.
Excuse me for my English!
So back to the thread, assuming both bino have relatively the same optical quality, practically in a dark we will see more detail with VP 8x25 than Curio 7x21 under the same conditions: same distance to the target, same low light.
Excuse me for my English!
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Gijs van Ginkel
Well-known member
dorubird, post 27,
Your final sentence about seeing more detail with the VP 8x25 as with the Curio 7x21: did you measure it or check it in reality or is it an opinion?
Gijs van Ginkel
Your final sentence about seeing more detail with the VP 8x25 as with the Curio 7x21: did you measure it or check it in reality or is it an opinion?
Gijs van Ginkel
dorubird
The unskilled mechanic blames his tools!
Opinion! It is an generic assuming based on relationship between magnification and apertures of this binoculars, "assuming both bino have relatively the same optical quality"...from your useful tests it appears that they have at least a very similar light transmission. (on this occasion thank you for your effort in testing so many and different binoculars categories https://www.houseofoutdoor.com/verrekijkers/verrekijkers-testen-en-vergelijken/ 
)
)
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Gijs,
I have no objection about the impact of color distribution for the eye's perception of brightness. Conquest HD 8x42 is stated to have 90% transmission and NL Pure 8x42 91%.
Do I notice 1% brightness difference? No.
Do I notice difference between these bins? Yes.
NL Pure has a cooler, or "whiter" image with more contrast. So I understand it's probably a result of the difference in color distribution.
But this is not what's this discussion is about. I am talking about the main decisive factor for relative brightness. Whatever configuration with identical light transmission and color distribution it's a fact that relative brightness is proportional to exit pupil area.
An optical system like a binocular with prisms can gather more light than naked eye, but never provide a brighter image. At most ca 96% of the naked eye.
I have no objection about the impact of color distribution for the eye's perception of brightness. Conquest HD 8x42 is stated to have 90% transmission and NL Pure 8x42 91%.
Do I notice 1% brightness difference? No.
Do I notice difference between these bins? Yes.
NL Pure has a cooler, or "whiter" image with more contrast. So I understand it's probably a result of the difference in color distribution.
But this is not what's this discussion is about. I am talking about the main decisive factor for relative brightness. Whatever configuration with identical light transmission and color distribution it's a fact that relative brightness is proportional to exit pupil area.
An optical system like a binocular with prisms can gather more light than naked eye, but never provide a brighter image. At most ca 96% of the naked eye.
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Dorubird #27,
"In less scientific terms we can say that the 10x50 are "brighter" in same low light situation than 6x30 because perceive more information, even if it is only a matter of perception resolution (practically we see in a dark more details with 10x50 than 6x30"
Yes, that's less scientific. Everything else being identical, the difference between 6x30 and 10x50 is simply the difference between watching an object with naked eye at 10 vs 6m distance. The distance to an object does not affect the brightness.
"In less scientific terms we can say that the 10x50 are "brighter" in same low light situation than 6x30 because perceive more information, even if it is only a matter of perception resolution (practically we see in a dark more details with 10x50 than 6x30"
Yes, that's less scientific. Everything else being identical, the difference between 6x30 and 10x50 is simply the difference between watching an object with naked eye at 10 vs 6m distance. The distance to an object does not affect the brightness.
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Gijs van Ginkel
Well-known member
Swedpat, post 30,
I took us a lot of words, but I agree with your statement here.
Gijs van Ginkel
I took us a lot of words, but I agree with your statement here.
Gijs van Ginkel
Gijs van Ginkel
Well-known member
Dorubird, post 27,
This morning I made a car drive of about 40 km to House of Outdoor to check the differences bewteen the Curio 7x21 and Zeiss Victory 8x25 and it is crystal clear to me that the Curio 7x21 produces a much more brilliant image then the Zeiss Victory 8x25 while I can not observe a difference in light gathering properties between both binoculars. It was a sunny day and the subject of observation consisted of brick walls with different coloured stones, a green wooden panel, white structures and a dark corner with a stone structure. The image of the Curio sparkles while the Zeiss image is "duller"so to speak..
Gijs van Ginkel
This morning I made a car drive of about 40 km to House of Outdoor to check the differences bewteen the Curio 7x21 and Zeiss Victory 8x25 and it is crystal clear to me that the Curio 7x21 produces a much more brilliant image then the Zeiss Victory 8x25 while I can not observe a difference in light gathering properties between both binoculars. It was a sunny day and the subject of observation consisted of brick walls with different coloured stones, a green wooden panel, white structures and a dark corner with a stone structure. The image of the Curio sparkles while the Zeiss image is "duller"so to speak..
Gijs van Ginkel
After reading you post, I made the same comparison under a cloudy sky. Same conclusion.
The Zeiss is no slouch but the Curio are really something special.
The first time he looked through them, my son who has no interest in optics was amazed.
dorubird
The unskilled mechanic blames his tools!
Gij van Ginkel, post 33,
I'm not surprised that you find that Curio 7x21 has a higher contrast because the VP 8x25 has a very quiet contrast image signature, "duller" as you said. But it doesn't bother me personally because VP has a better dynamics/ gray tone instead, useful especially in shaded areas, and olso excellent resolution. My Leica Trinovid 8x20 has a much higher contrast/sparkles than VP 8x25 olso.
Withal, in general all the 7x binoculars in sunny day time often "sparkles" more than 8x or 10x one. I don't know why, may be because 7x has a deeper depth of field so the density of the information makes pop up more contrasting! But at night time the aperture rules! This is a personal opinion!
I'm not surprised that you find that Curio 7x21 has a higher contrast because the VP 8x25 has a very quiet contrast image signature, "duller" as you said. But it doesn't bother me personally because VP has a better dynamics/ gray tone instead, useful especially in shaded areas, and olso excellent resolution. My Leica Trinovid 8x20 has a much higher contrast/sparkles than VP 8x25 olso.
Withal, in general all the 7x binoculars in sunny day time often "sparkles" more than 8x or 10x one. I don't know why, may be because 7x has a deeper depth of field so the density of the information makes pop up more contrasting! But at night time the aperture rules! This is a personal opinion!
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Lee,
With dual hinge pockets, IME it's a matter of finding the right relationship between
(1) Focusing tension and enough hinge tension to prevent movement of IP setting during focusing.
(2) Hinge tension which allows the user to easily set the IP distance symmetrically, and
(3) Sufficient hinge tension to keep the IP setting in place in reasonable use.
For me the Curio, the 8x20 and 10x25 UV, and the Opticron 8x21 and 10x25 work best checking all three. Conversely, SW 8x20 Habicht and previous gen 8x25 CL have slightly looser hinges making it fiddly for me to easily set IP, and IP tends to move in normal use. But the IP on the SW's does not move when focusing.
Mike
I've hot had problems with hinges moving on the current CL 8x25, but surely a single hinge model with too loose a hinge presents similar problems in retaining IP?
Richard,
Yes I would think so as well. But I haven't had a similar problem with a single hinge pocket. It is clear from the many positive reviews of the CL and 8x20 Habicht that the hinge tension is fine for most people, it's just a bit loose for my handling style, maybe hand size, etc. I have a couple of full size bins on which the hinge tension is very near too tight and would imagine that a dual hinge pocket with overly tight hinges would be the worst in terms of easily setting the IP symmetrically.
For anyone reading with general interest, the hinge tension on my MIJ Terra 8x25 works great for me as well. I have often thought that the standard issue "try before you buy" advice applies especially to dual hinge pockets where smaller differences can make bigger differences to the user.
Cheers,
Mike
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