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Is it my eyes? (1 Viewer)

jnielsen

Well-known member
I just received a new binocular the other day so I set off to do some comparisons to my other binoculars.

I spent about 2 hours in the backyard last evening and compared three binoculars against each other for brightness and clarity until it was dark.

My new binocular received is a Steiner Nighthunter XP in 10x56.
For a fair comparison I tested it against my Leupold 8x42 Golden ring HD and Meopta Meostar B1 10x42. I did not include my Swarovski EL swarovision 8.5x42 as I know how it compares to the Leupold and Meopta.

All were about on even terms as far as sharpness (leupold best) and CA (again leupold best).

The big shock to me was the brightness in low light. The 56mm nighthunter did not show any advantage over the other two binoculars! None at all!

Another surprise to me was the 8x42 Golden ring HD had no brightness advantage in low light over the Meopta 10x42.

I was able to pick up more detail at distant objects with both the 10x glasses over the 8x42 in very low light levels.

This leads me to believe that perhaps the pupils in my eyes have no use for the larger exit pupils of the 8x42 and 10x56.

For the record I have 20/20 vision.

Any ideas?
 

etudiant

Registered User
Supporter
Pending input from someone expert like Frank, you are quite right, at least afaik.
If the pupils no longer open up beyond say 4mm, the bigger glass will not add brightness, just ease of positioning/view maybe.
I believe 20/20 vision only covers sharpness of view, but not brightness aspects.
 

FrankD

Well-known member
I appreciate the kind words etudiant but this isn't my usual cup of tea. I would rely on folks like Henry, Looksharp or Elkclub to chime in. They are much more knowledgable when it comes to the human eye and how it impacts our perceptions.
 

[email protected]

Well-known member
Supporter
I just received a new binocular the other day so I set off to do some comparisons to my other binoculars.

I spent about 2 hours in the backyard last evening and compared three binoculars against each other for brightness and clarity until it was dark.

My new binocular received is a Steiner Nighthunter XP in 10x56.
For a fair comparison I tested it against my Leupold 8x42 Golden ring HD and Meopta Meostar B1 10x42. I did not include my Swarovski EL swarovision 8.5x42 as I know how it compares to the Leupold and Meopta.

All were about on even terms as far as sharpness (leupold best) and CA (again leupold best).

The big shock to me was the brightness in low light. The 56mm nighthunter did not show any advantage over the other two binoculars! None at all!

Another surprise to me was the 8x42 Golden ring HD had no brightness advantage in low light over the Meopta 10x42.

I was able to pick up more detail at distant objects with both the 10x glasses over the 8x42 in very low light levels.

This leads me to believe that perhaps the pupils in my eyes have no use for the larger exit pupils of the 8x42 and 10x56.

For the record I have 20/20 vision.

Any ideas?
It depends on your age. As you get older your pupils won't dilate as much as when you are young so 4 to 5 mm might be your max. Also, given equally good coatings a 10x will show more detail at dusk because of the "Twilight Factor". The twilight factor is found by multiplying the size of the objective lens (in mm) by the magnification and then finding the square root of that result. The larger the twilight factor, the more detail you can see in low light. A twilight factor of 17 or better if usually required for reasonable low light use. That is why for most birding in daylight situations a 32mm is a good compromise. Except for maybe 15 to 20 minutes at dusk it is going to be just as bright as those big 56mm's for most people over 40 years old. I had a 7x50 Fujinon once and my 32mm Swarovision was just as bright most of the time. Of course it depends a lot on the quality of your coatings also. It is weird but I guess your eyes can only take so much light in at once.
 

OPTIC_NUT

Well-known member
Nice summary!. 7mm is about the widest your pupil goes, and it averages
4-5 mm in your 40s-50s. And if we can believe the awesome coatings claims
for most modern binocs, the brightness will seem the same. For you to notice something
as "dimmer", it would have to be 30-50% less, as I recall from the first optics lab.
Note the the light does down as the square of the aperature, though. It takes its
toll.

But there are reasons for a bit of extra exit pupil. At sea, they need the 7x50 to
avoid things winking when the rolling boat and the body get a bit out of line. Easier to
let that happen and the sight line be true than to work the body and binoculars both
as perfect. You can acquire a target faster, too, since placement of eyes is not
so fussy.

Really frustrating about not being able to cram more light though, isn't it?
I can understand design for flatness, phase uniformity, and depth to some extent,
but why the exit pupil formula can't be escaped I can't quite get. One engineer
expressed it as...that "you cannot more light density in a cone than in the original."
Non-focused: you can concentrate. Focused: no.
Even shown the ray-tracing, I couldn't really feel the 'why' of it.
 
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pompadour

Well-known member
This is my experience. First, my pupil opens to at least 5 mm, acuity ~20/15. • In dim as in good light a higher x bin can* show more of useful detail than a lower x bin with better optical quality and bigger exit pupil • In good light, possibly also dim, an exit pupil bigger than the eye's can* add more detail (and perceived brightness). It may be that in this case the M's sharpness and contrast is that much better than the S's that this is cancelled. *At a certain level of opt. quality.
 

typo

Well-known member
While many studies have shown that pupil dilation decreases with age, they also show that it's very variable between individuals. At the age of 60 for instance the average is around 5mm but the range is from below 4mm to about 7mm. A number of methods for estimating for yourself have been described here including Henry's, but your eye doc can check it for you.
http://www.birdforum.net/showpost.php?p=2932217&postcount=12

I suspect some of the confusion in comments here come form how we individually define low light. The eye is designed to work over about a billion fold range in light level but the pupil of the eye only changes about 50 fold in area over a comparable light range (less as we get older). Though I'm simplifying things a lot, outside that 50 fold range our eyes still work, but we progressively see reduced detail, contrast and colour. We could compare each of those separately with regard to binoculars but I suspect it's colour that most birdwatchers notice first, whether it's the pupil of the eye or the binocular's exit pupil that is limiting.

I'll just confine my comments to colour for the moment and it includes some speculation on my part.

I sure we all know we have three colour receptors in the eye and a separate set for night vision. The colour receptors are most densely packed in the centre of the retina (fovea) and also account for our highest acuity. Of our colour receptors the green is most sensitive and the blue the worst, so as light fades we loose the ability to see blues first, we become partially colour blind. I suspect this is something that bird watchers are more acutely aware of than hunters, mariners, military and other binocular users.

Traditionally manufacturers concentrated on transmission performance at 550nm for daylight use as the peak of colour sensitivity. My personal view is that a few percent difference at this wavelength makes little practical difference when you consider the overall change in magnitude in failing light. However the differences in the transmission in the blue are often much more substantial. Tens of percent in some cases. It's taken a bit of time to figure this out but for me, and I suspect for others, it's this relative change in the blue that influences my perception of low light colour, and judgement of 'brightness'. Older designs with basic lens coatings or silver mirroring on the prisms may be very poor in the blue. We are probably more sensitive to the glue/green ratio than absolute values.

Allbinos transmission plots of the Swaro ELSV 10x42 shows about 94% transmission in the blue (450nM), the Zeiss FL is closer to 85% but the Zeiss has the higher green transmission (~94% vs. ~89%). Technically the Zeiss has the superior low light colour performance which might be detectable in some conditions, but I suspect many consider the Swaro to be 'brighter'. This might be most acute at twilight when the residual light can be substantially red shifted.

Just my 2 cents.

David
 

WJC

Well-known member
I haven't read the whole thread as I should have. However, your pupil is not totally dependent on age.

Your 56mm--if properly baffled, and with even reasonable coatings--should show you its stuff in low light. In daylight, your pupil is stopped down to the point at which most of the light bundle is falling on your IRIS, and not your retina.

I have bigger binos for astronomy and my 8x32s for birding. Unless you're Buford Puser, you don't go bear hunting with a switch or squirrel hunting with a 7mm magnum.

Just a thought,

Bill
 

Gijs van Ginkel

Well-known member
David post 8,
You mentioned in your post 8 that Allbinos measured a transmission of 94% at 450 nm for the Swarovision 10x42. We also measured its transmission spectra but we never got such high transmission values at 450 nm. We found approx. 80% both for the 10x42 EL-SV as well as for the 10x42 SLC. Looking into our files we never found in all the many, many binoculars we have investigated in the course of the years such high transmission values at 450 nm. even the Zeiss HT does not reach transmission values of 90% at 450 nm, it is closer to 85%. So there are some puzzles to solve.
Gijs
 

Hermann

Well-known member
You mentioned in your post 8 that Allbinos measured a transmission of 94% at 450 nm for the Swarovision 10x42. We also measured its transmission spectra but we never got such high transmission values at 450 nm. We found approx. 80% both for the 10x42 EL-SV as well as for the 10x42 SLC.

Some of the measurements by Allbinos are a bit strange, to put it mildly. I trust your measurements a lot more than Allbino's.

Hermann
 

typo

Well-known member
Gijs,

I'm aware that ELSV 10x42 profile gives a higher sub 500nm transmission than some of yours and indeed other Allbinos' profiles. I can't be sure of the reasons, but I used that as a more obvious illustration of what I've observed in trying something over 30 Swarovski binocular samples in the last couple of years. I couldn't say if it''s batch variation or an incremental evolution but there is a distinctly bluer bias in the more recent ELSV and SLCs I've tried when compared to the other alphas, though I've noted the Nikon EDG and now the Zeiss HT appear to have a stronger performance in the blue than many.

I chose to mention the Swaro ELSV/Zeiss FL as I've directly compared them in failing light. It was quite striking that the Swaro held on to a broader colour spectrum longer than the FL and initially gave the impression of being brighter, but equally clear as it got darker I could still see greens with the FL when the Swaro had gone monchrome. It seemed constant with those transmission profiles. I've done similar comparisons with the more humble collection I own and others I've reviewed. As a general rule I found the models with relatively better blue performance often appear brighter in some light conditions particularly twilight, but do not necessarily come out top at the limit of photopic vision or scotopic conditions.

David
 

WJC

Well-known member
Some of the measurements by Allbinos are a bit strange, to put it mildly. I trust your measurements a lot more than Allbino's.

Hermann

Pioneer Marketing (once of Steiner fame) had an ad for their Navy One binocular that stated:

“its SPARC optics feed reflected electromagnetic energy back into the light beam . . .”

That may turn your stomach, but it made Aunt Myrtle weak in the knees. ;)

Bill
 

jnielsen

Well-known member
Ok I did some full dark comparisons with the 10x56 and 10x42.

The 56mm glass in full dark with only artificial light coming from house lights ect. is slightly brighter than the 10x42. Certainly not enough for me to lug the 10x56 around during hunting season.

Thanks for the comments.

Interesting that the tread mentioned the transmission of the Swarovision and Zeiss FL characteristics in low light.

I used to own a 10x42 FL and Upgraded to the 8.5x42 Swarovision because to my eyes it was just as bright but also was sharper and showed more resoulution in low light. Also better contrast.
 

WJC

Well-known member
Ok I did some full dark comparisons with the 10x56 and 10x42.

The 56mm glass in full dark with only artificial light coming from house lights ect. is slightly brighter than the 10x42. Certainly not enough for me to lug the 10x56 around during hunting season.

Thanks for the comments.

Interesting that the tread mentioned the transmission of the Swarovision and Zeiss FL characteristics in low light.

I used to own a 10x42 FL and Upgraded to the 8.5x42 Swarovision because to my eyes it was just as bright but also was sharper and showed more resoulution in low light. Also better contrast.

That's why I use an 8x32 for birding. The following addresses another bugbear misconception of observers:

10 “MY BINOCULAR HAS AS MUCH LIGHT GRASP AS MY TELESCOPE”

Fallacy: The light grasp of a binocular is the sum of the light striking BOTH objective lenses.

Fact: Actually, it’s only slightly more than the light grasp of one of the objectives. :eek!:

This misconception is especially prevalent among amateurs who use binoculars as their chief instrument. Because so many of the things they want to view are dim asterisms and diffuse objects, they want the most light-grasp they can get from a binocular—or telescope.

This need has given rise to the notion that a binocular’s light grasp is the sum of the light striking both objective lenses. While that may be intuitive, it’s wrong! Is there an increase in brightness by using binocular over monocular vision? Yes. But the difference is only slight.

Wishing to avoid calculations and theories of binocular summation, you may prove this yourself.

Look out the window: day or night, clear or foggy. Then cover one of your eyes. Did your view diminish in brightness by 50%? Why not? You decreased your perceived image brightness by 50%!

The answer lies in how the brain’s part of our optical system works, which is not always the way we think it should. It’s important to realize the brain is far more sophisticated than a piece of mechanical optical gear and, unlike a camera, doesn’t work on mathematical constants.
 

ronh

Well-known member
I have a single coated German military surplus Hensoldt 8x30, which despite the obvious strikes against it still shows a LOT more than unaided vision in very low light.

For all our heaving and sighing, different specs, from 6x to 12x and from 30mm to 60mm, are way more same than different. Quality is what provides the fun factor. A good anything x anything beats a poor anything else x anything else.

Ron
 

Troubador

Moderator
Staff member
Supporter
I have a single coated German military surplus Hensoldt 8x30, which despite the obvious strikes against it still shows a LOT more than unaided vision in very low light.

For all our heaving and sighing, different specs, from 6x to 12x and from 30mm to 60mm, are way more same than different. Quality is what provides the fun factor. A good anything x anything beats a poor anything else x anything else.

Ron

Nicely put Ron, very nicely put.

And the fact that over here in the UK, heaving = vomiting, only makes your comment more apt. :smoke:

Lee
 

pompadour

Well-known member
Ron, I'm shocked. Here in Bf. we don't discuss poor anything - except maybe to say, in the year dot I started bird watching with a much-loved Xxx, but now I just cannot imagine how ... etc. Staying in more familiar Bf. territory, I would say, in low light a good anything (m1) x anything (d1) is better than an excellent anything (m2) x anything (d2) if m1 > m2. (Note: some poetic license, but less than yours I hope.)
 
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