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Daytime benefit of large objectives? (1 Viewer)
- Thread starter tenex
- Start date
Hermann
Well-known member
How useful will be the additional brightness due to the larger exit pupil if you can't use it - simply because your eye pupils contract to something like 2.5mm in daylight?
Larger eye relief? That's plainly not true. The eye relief depends on the type of eyepiece used. Period.
Depends. If you're out hiking in the mountains carrying a large pack with your camping gear I seriously doubt a 10x50 will be easier to use than a smaller binocular ...
Hermann
Hermann
Well-known member
An 8x56 will leave an 8x50 in the dust? And it's not that much bigger?
I'm out of this discussion.
Hermann
looksharp65
Well-known member
So, more exactly, HOW is the larger objective brighter? Beats me when I try to understand your assertion.
Are you not admitting that there are occasions when the user cannot use all the light that comes through the exit pupil?
While optical brightness of binoculars is determined by the exit pupil size, by squaring it, the user position is the guiding principle for how to gradate brightness for that individual user and at the momentary level of illumination.
The technical brightness value does not tell the final truth about how bright the binoculars will appear. It does tell that they have the possibility to deliver more light to the eye, not that they will always appear brighter.
There was a recent discussion where there were claims that binoculars with too large objectives/too large exit pupils would actually be less bright than those with objective sizes that match the user's pupil.
Exactly the opposite to what you claim.
That is incorrect, just like your idea that big objective binoculars will always be brighter (if that's what you're saying)
I maintain it's only brighter compared to a smaller exit pupil binocular when at least the smaller exit pupil is smaller than the user's pupil.
If both are smaller than the user's pupil, the larger exit pupil will be the brighter anyway.
And no, eye relief has exactly nothing to do with this. It's just optics / science 101.
Now, if I look at a huge wall with uniform colour and brightness, and then I take a swimming ring and look through it, the wall's brightness won't be any different. And going from the swimming ring, via a napkin ring to a 10 mm hole in a black sheet of paper, nothing will change the perceived brightness of the wall. Same brightness - no more, no less.
But as soon as the hole is smaller than your own pupil, the perceived brightness will decrease because the exit pupil now substitutes your pupil as the limiting aperture of your eye's optical system.
It is not the objective size that determines the perceived brightness, it is the exit pupil size, but the perceived brightness will not decrease until the exit pupil is smaller than your own pupil.
In reality, this means that if your pupil is restricted to an absolute maximum of 3 mm, a 10x30 will for you always be as bright as a 10x70.
One could admit that the bigger exit pupil "scientifically" is brighter than the smaller one, but that line of thinking violates the very concept of how binoculars are used. If you're totally blind and cannot even perceive light, the notion of a "brighter" binocular, or for that matter one with more magnification, is useless.
Binoculars' usefulness is inseparably associated with the human vision, and not one of their optical properties have any meaning without the user.
So using the phrase "user issues", "user problems" as if those were rare exceptions, and claiming the greater geometrical brightness to be almost always noticeable and useful, is misleading.
//L
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gunut
Registered Offender
lets just say the 8x56 is easy to use even if you use poor observing technic...just throw them up to your face and you will have a good sight picture....with that large exit pupil a little off center...fine...... bins spread a little to much or not enough...fine.......you don't have to have everything lined up perfectly to get that comfortable professional view....I use mine a lot if I don't have to lug them around...and mine a are relatively light...
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With a 3mm maximum eye pupil size the 10x30 will only be as bright as the 10x70 if the eyes are exactly lined up with the 10x30 exit pupils.
In use perhaps only 2mm or 2.5mm of the exit pupils might be used, perhaps on one barrel.
Also the 10x30 might actually be 10x27 if slightly vignetted.
So sometimes the 10x30 might appear to be not as bright as the 10x70.
I have no trouble lining up the 10x25 Docter binocular, but some people do have such problems.
In use perhaps only 2mm or 2.5mm of the exit pupils might be used, perhaps on one barrel.
Also the 10x30 might actually be 10x27 if slightly vignetted.
So sometimes the 10x30 might appear to be not as bright as the 10x70.
I have no trouble lining up the 10x25 Docter binocular, but some people do have such problems.
looksharp65
Well-known member
This is true. And pupils tend to be slightly decentered from the optical axis of the eye, and aren't necessary perfectly circular, which means that some "excess" exit pupil size doesn't harm.
Since I find 4 mm exit pupils perfectly servicable, and for the most avoid going above 8x magnification, 8x32 suits me very well.
I looked through the new CL's recently, and much preferred the 8x.
Quite nice little thing actually.
Don't know if this is a Meopta ocular's thing, but both the 8x32 and the 12x50 HD Meostars are really easy to "throw up" in front of the eyes.
The EDG 7x42, not to mention the ZR 7x43, are definitely more sensitive with regard to eye placement than the Meostars, despite their much bigger exit pupils.
//L
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etc
Well-known member
Precisely. That's why the classic marine binocular configuration is 7x50, resulting in a 7mm exit pupil size. The 8x56 has an identical exit pupil size. I am considering a 8x56 as an alternative to 10x56 that I want. Tough choice it is.
Let's say a 56mm is considerably bigger than a 50mm. It is like comparing a 42mm to a 50mm. I had 50mm binoculars and there is a big jump in performance when going to a 56mm especially low light. That is why hunters in Europe use them at dusk.
Sorry guys, there may be some ease of use benefits to a larger exit pupil, but in normal daylight bigger objectives do not mean an increase in radiant flux at the retina. That's one of the fundamental rules of physics. Bigger objectives mean more glass, and that means greater absorption, and lower flux per square millimetre. On the other hand brightness is a perception. A property of psycology. Sometimes what individual users think they see has nothing to do with reality.
David
David
Sorry guys, there may be some ease of use benefits to a larger exit pupil, but in normal daylight bigger objectives do not mean an increase in radiant flux at the retina. That's one of the fundamental rules of physics. Bigger objectives mean more glass, and that means greater absorption, and lower flux per square millimetre. On the other hand brightness is a perception. A property of psycology. Sometimes what individual users think they see has nothing to do with reality.
Indeed!
The 7x50 Nikon WX is the most impressive binocular I have ever viewed through, but its transmission values are apparently rather mediocre.
John
John,
I've not seen the WX, but I do know high resolution, low distortion and wide FoVs can really impress. However I also understand that, for my use, it cannot do a better job in low light than my 8x42, let alone my 10x56. Check out the work of Merlitz, Blackwell, Berek and others. In fact a 4mm EP covers nearly all my birding needs, with zero impact on brightness.
David
Big EP's such as in the Nikon 7x50 WX have more benefits than that. Don't forget Henry's testing and reasoning on why he carries an 8x56 FL for birding. The on-axis view is clearer and more transparent with less aberrations with those big 7mm EP's and you get almost no veiling glare.
https://www.birdforum.net/showpost.php?p=840895&postcount=1
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dries1
Member
LG objectives
That was funny, something Carlin would say during stand-up. I do agree with David, 8X42 does everything for me for terrestrial viewing, and use 10X for astroooooooo.
A.W.
was that a burn??....sounded like quite the attempt at a burn to me...now Den is used to that....but I am unaccustomed to that type of attitude....B
That was funny, something Carlin would say during stand-up. I do agree with David, 8X42 does everything for me for terrestrial viewing, and use 10X for astroooooooo.
A.W.
etc
Well-known member
I never thought I would consider a 8x56mm. Either that, or 10x56.....
Neither one would replace a 8.5x42mm EL which seems compact in comparison.
etc
Well-known member
I've read it.
Now I am assuming that the logic applies to any 8x56mm not just FL.
henry link
Well-known member
I assumed the same thing until I tried the 8x54 HT and found that some large exit pupil binoculars don't meet expectations.
https://www.birdforum.net/showthread.php?t=285414
I'm surprised to see large binoculars getting so much attention lately. I'm afraid much of it is due to Dennis' proselytizing, which I predict won't last long.
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Dennis,
What Henry observed for his his 8x56 FL isn't particularly unusual, and it's certainly not exclusive to 40oz+ or 7mm EP binoculars. I saw pretty much the same thing with the Fuji version of the Sightron BS II 8x32 I borrowed for review. The trick is to be able to spot the good ones before you buy. I have tried the Swarovski SLC 8x56. It didn't do it for me, but I'm sure you will enjoy a long and happy relationship.
David
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