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Anonymous
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  I must have missed something please advise. Has anybody measured brightness through
diffrent binoculars with the same power and aperature through a light meter? As subjective opinions can be,
wont a fixed source of light and a meter provide constants
respective of each brand and features? thus eliminating the human factor?
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wilash
Fairy Godmother
Reged: 09/30/03
Posts: 5746
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It is possible, but trickier to set up than it appears.
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Anonymous
Unregistered
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There is a Dutch site with a review of spotting scopes for birding that did just such a thing. I have also seen on Bird Forum percentage transmission value for various top end birding binoculars. However it was not clear whether the figures were peak values, or averaged over the visible spectrum. Also it is not clear to me if such values directly relate to perceived brightness. After all an optic could transmit 100% of the incident light, but if it had low contrast it would often give a dimmer than expected image (except when viewing e.g. a white sheet of paper). IN other words I suspect that performance is a function of transmission and contrast (or optical quality).
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Anonymous
Unregistered
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I have never heard of anyone doing this. It's curious though. This sounds like an experiment waiting for soomeone...
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lighttrap
Reged: 02/06/04
Posts: 3833
Loc: cloudy, foggy, humid NC, US
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This is a good idea. I'm not entirely sure that the results would be meaningful, but I'm willing to try. Currently, my Sekonic L508 light meter is out on loan. I'll get it back and conduct some tests. That particular meter might prove especially useful because it's got spot-metering.
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18" Starsplitter II f/4.5
8" Hardin Dob f/6
C5 workhorse mini SCT f/10 or f/6.3
70mm TV Ranger dual purpose birding/astro
77mm Leica Televid APO
16x70 Fujinons on UA Deluxe Mt.
12x50 Nikon SE
8x30 Nikon E2s
and many others
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btschumy
Think Astronomy
Reged: 04/13/04
Posts: 1110
Loc: Austin, TX, USA
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This might also be something you could do with a digital camera held up to the eyepiece (with appropriate shielding). Afterwards, you could take the image(s) into Photoshop and perform various measurements as to average image brightness, average contrast, etc. Seems like it should be straightforward enough.
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Bill Tschumy
Where is M13? Freeware -- Add a new dimension to your observing.
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Anonymous
Unregistered
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The actual value from the light meter is not that important (at least to me anyway). It is how the results change from bino to bino that's of interest. As long as the measurement method doesn't change, it would be an interesting relative measurement I think.
Go for it! 
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Has merit for a measure of overall brightness, but
It won't tell you anything about the distribution of the light across the exit pupil, which is one of the things we want to know. I don't think even spot metering is going to capture any differences across a 4mm or 5mm exit pupil.
A brighter binocular could be concentrating most of it's light in the central portion of the exit pupil. If illumination falls off considerably in the outer 60% of the exit pupil, would a light meter be able to pick that up?
Suppose a slightly less bright binocular fully illuminates nearly the entire exit pupil. What would be the judgement of the above two binoculars.
I would consider the less bright, but fully illuminated exit pupil a better binocular.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Anonymous
Unregistered
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Thank you very much gentlemen. info like these is what makes this forum addicting.
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Anonymous
Unregistered
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Gentlemen,
You folks will probably prove me all wrong on this post but, that’s exactly what I want. I thought it was general knowledge that Fujinon “EBC” coating passed 95% of the light, much more than any other?? That the Fujinon FMT-SX 7x50 is the brightest, most contrasty, and best resolution, of any binocular, at any price, on this planet!! I am sure that Nikon comes close. I have seen an SE, but have not seen the Astrolux and Prostar. I know the SE comes close, I’ll bet those other two come close, also. OK, you knowledgeable folks, please tell me where I am wrong, and set me straight, as I would like to purchase the very best for my tired eyes. At this moment, it appears to me that, the best $ for $ bins out there, or the best at any price, are Fujinons. (I must add for most applications.) Are we talking of taking some kind of meter into a store and checking all the bins??
Edited by KAC (09/25/04 08:00 PM)
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Quote:
Gentlemen,
You folks will probably prove me all wrong on this post but, that’s exactly what I want. I thought it was general knowledge that Fujinon “EBC” coating passed 95% of the light, much more than any other?? That the Fujinon FMT-SX 7x50 is the brightest, most contrasty, and best resolution, of any binocular, at any price, on this planet!! I am sure that Nikon comes close. I have seen an SE, but have not seen the Astrolux and Prostar. I know the SE comes close, I’ll bet those other two come close, also. OK, you knowledgeable folks, please tell me where I am wrong, and set me straight, as I would like to purchase the very best for my tired eyes. At this moment, it appears to me that, the best $ for $ bins out there, or the best at any price, are Fujinons. (I must add for most applications.) Are we talking of taking some kind of meter into a store and checking all the bins??
Man those are strong words. Honestly, I don't know which is best. And, if it is your desire to know exactly the percent light transmission, then you would need laboratory equipment to do the testimg.
But you did prompt me to pick up my 10x70 Funinon FMT-SX and my Nikon 12x50 SE and walk outside to do a comparison of the reflectivity off the coatings. (Actually, I just came in from comparing about 10 different binoculars).
A week or two ago, I picked up a pair of Nikon 12x50 SE. When I first picked up that binocular I was startled when I looked at the coatings. At first glance, you can't see any light reflected off the coatings.
Now I must tell you I hold the Fujinon in the highest regard. The 10x70 and the 16x70 are the same binocular with a different eyepiece. For a long time, I have felt they have the best coatings of any binocular I own.
Keep in mind, these two ( the Fujinon FMT-SX and the Nikon SE) are the best of all the binoculars I own. Probably next best to those above is the Oberwerk BT100. Then there's a few Pentax binoculars in the mix that are pretty good, and a fine Swift Ultralite, and the Oberwerk 15x70 holds its own, but these two above are the best. And all these binoculars reflect a slightly different color back to you, varying from a purplish to blue/green/purple to yellowish/green to just green. If coatings are applied properly, color is not an indication of the quality, only a result of the chemical composition of the coatings.
One way to tell, comparativly, how much light gets through the coatings is to look for how much light is being reflected back off the coatings. You really can't tell much by looking at just one binocular. You need to see a range of binoculars to see different amounts of reflection.
So this is it, the first time I'm picking up these two binoculars to look at them side by side.
Standing with my face in full sunlight and using the binoculars as a mirror, looking into the objectives, then standing in shade but still in outdoor light, again using the binocular objective like a mirror to look for my reflection and try to see how much detail I can pick out in my reflection.
Without a doubt the Nikon 12x50SE reflects LESS light off the objective lens than the Fujinon 10x70 FMT-SX.
Man, it's hard to see any reflected light coming off the Nikon 12x50 SE. very difficult to see the entire outline of my head. No facial light, no features visible, just a faint dark outline of my head.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
Edited by EdZ (09/26/04 04:32 PM)
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KennyJ
Reged: 04/27/03
Posts: 10146
Loc: Lancashire UK
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Ed,
Just as I was getting REALLY interested -- your last post came to an abrupt halt :-)
I hope more is to follow comparing these two fine specimens
P.S how about a comparo between the Nikon SEs and Extremes?
Regards , Kenny.
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If everyone is thinking the same thing , no-one is thinking - General George S.Patton
Zeiss 7 x 42 BGAT
Captain's Helmsman 7 x 50
Nikon 10 x 42 Superior E
Swift Audubon Kestrel 10 x 50
Helios 15 x 70 Observation
Strathspey 20 x 90
Televue 76 APO
Zeiss 85 Diascope
Helios 102 f5 refractor
Various eyepieces barlows tripods mounts etc.
Panasonic Lumix DMC - TZ5 digital camera
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Kenny,
another dozen or so binoculars out the front door. OK here ya go.
Here's how I check the coatings on binocular objectives.
If you look at the Action Extremes with no other binocular next to them to compare, the coatings look great. I have three pair of the Nikon AE's, the 12x50, the 10x50 and the 8x40. The coatings are perfectly consistent across the three.
When you compare the Nikon Action Extreme coatings up against all these others, the Swift Ultralite 8x42, the Oberwerk 15x70/'03, my 5 year old Orion Ultraview 10x50, a new Pentax PCF WP 10x50, it's a different story. The Nikon AE objective coatings reflect more light than all of them. What you want is coatings that reflect the least amount of light.
My Pentax binoculars were all made at different times. The new PCF WP 10x50 is very good, the best of the Pentax coatings. It's better than the Orion Ultraview and about equal with the '03 Oberwerk. My oldest Pentax, a PCF III 12x50 is more purpulish, but fairly reflective, more reflective than the Swift, Orion and Oberwerk and Pentax PCF WP 10x50. The Nikon AE appear to reflect about the same as my Pentax PCF III 12x50. The PCF WP 16x60 are completely different coatings than the other two Pentax, yellowish green and highly reflective. Here's the description of the Pentax coatings.
I'd say the only binoculars the Nikon AE beat out were the older generation Oberwerk'02 and my yellow/green Pentax 16x60s.
The Nikon Action Extreme coatings should not even be considered for comparison to the Fujinon FMT-SX or the Nikon SE. They don't even come close.
edz
edited Nov 04
Both the Celestron Skymaster 25x100 and the Oberwerk Giant 22x100 have objective coatings that appear purple/green with very little reflection off the objective lens. Looking at reflected light inside the Oberwerk 22x100 shows a green reflection off the prism face towards the objective. The same prism face in the Celestron 25x100 shows a light blue reflection. The coatings on the Oberwerk eyepieces appear greenish. The eye lens and prism coatings on the Celestron 25x100 appear like they might be single coated MgF.
The 20x80 Oberwerk Standard has a fine coating on the objective that produces almost no reflection with full daylight. The coatings on this 20x80 binocular seem to reflect so little light, they appear better than the Oberwerk 15x70/'03 and maybe should be considered nearer to the Fujinon 16x70. The coatings on the Oberwerk BT100, judged by the amount of reflections coming off of them and the difficulty of seeing any detail in those reflections, appear to be one of the finest coatings I have seen.
The Nikon SE, Fujinon FMT-SX, Oberwerk BT100 and Oberwerk Standard reflect less than the Celestron 25x100 and the Oberwerk 22x100. These two have objective coatings probably closer to the Oberwerk 15x70/’03. Keep in mind the Celestron appear to have single coated prisms and eye lens.
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
Edited by EdZ (11/07/04 11:33 AM)
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Anonymous
Unregistered
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Dear Edz, since you got the stuff out ..please help
me in tryin to determine whether or not I got the pentax yellowish green coating. I just got my 20x60 & 10x50 PCF WP
V's this month. I see them as predominantly green with a
tinge of purple. Im just a newbie, is there a technique
on how to tell?
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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OK, back out. refer to previous post for method.
My Pentax PCF WP 10x50 have a bluish/slight purplish/very slight green tinge to the coating. It's difficult to pick up the reflection of my sunlit face. I cannot easily see the outline of my dark hair. I can't clearly make out any facial features, eyes nose or ears. I can pick up a glint of sunlight reflecting off of my glasses. When I look at the reflection of a blue sky in them it looks blush/very slight purplish.
My Pentax PCF WP 16x60 have a yellow green tinge to the coating. My sunlit reflection bounces off them like I'm looking into a mirror. I can see the color of my face, my hair, the detail of all the features on my face. I can clearly see a birthmark on the side of my face. Not only can I see my glasses I can clearly make out the dark frames. When I look at the reflection of the blue sky in them it is a very yellow green. Even in the shade, I can see facial features reflected in the coatings.
The more light you can see reflected in the coatings, the less light gets through.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
Edited by EdZ (11/07/04 11:35 AM)
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Anonymous
Unregistered
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Thank you very much Edz,. This will help me a lot. now ill go look.
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Anonymous
Unregistered
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Dear Edz, I followed your method and found out that i do not have the yellowish green coating. At first I thought
I was doing it wrong coz I couldnt see myself at all in direct sunlight. Eventually i was able to see the dark outline of my head and some features but not readily.In the shade the objectives to these two pentaxes show green at one angle and purple at another.The blue sky reflects as
bluish purple. I feel better already. Like always I am very
gratefull to you Edz. Jake
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holger_merlitz
sage
Reged: 02/08/04
Posts: 282
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Hi Ed,
I have seen a couple of binoculars, even some of medium-range price tag, which seemed to have uncoated EXTERNAL lens-surfaces, although properly coated inside. I agree that it is of more importance to coat internal lenses, which would otherwise produce horrible ghost images, but I wonder why they do not simply finish up their job and take care for the external surface, too. Maybe, external coatings have to be more robust and are therefore especially expensive, so that some manufacturers decide to accept a few % loss of transmission and keep these parts uncoated.
With regards,
Holger
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Hi Holger,
I know there may be some binoculars out there that are really made on the cheap, but none of the binoculars that I've seen that were manufactured in the last 20 years have uncoated external lenses. Even my oldest Sears binoculars, bought sometime in the early 80s for $29, are single MgF coated. An inexpensive pair of Nikon Sky and Earth from about 10 years ago are multicoated and a Minolta Classic from about 8-10 years ago are single coated.
I know Holger is well informed. For those others reading in here, an uncoated lens surface can reflect 4% of the light hitting it. MgF single coating can reduce that to 1.5%. Properly applied multicoatings can reduce that reflectance to 0.5% or 0.25% per lens surface. Improperly applied multicoatings may do no better than or not even as good as good single coatings. A binocular may have as many as 14 lens surfaces. Even a properly muticoated binocular can transmit at best only about 93% to 96% of incoming light. The same binocular with 14 surfaces if MgF single coated may transmit only 79% of the light.
Some of my older binoculars appear to have uncoated prisms. That's a lot of internal light loss. A binocular with uncoated prisms, with 4 prism surfaces, may have lost about 17% of the incoming light just through the prisms.
Coatings are a very important product in the transmission of light. In this age of products, no one should purchase binocular that have uncoated surfaces.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Erik D
Carpal Tunnel
Reged: 04/28/03
Posts: 2554
Loc: Central New Jersey, USA
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Quote:
Hi Ed,
I have seen a couple of binoculars, even some of medium-range price tag, which seemed to have uncoated EXTERNAL lens-surfaces, although properly coated inside. I agree that it is of more importance to coat internal lenses, which would otherwise produce horrible ghost images, but I wonder why they do not simply finish up their job and take care for the external surface, too.
Maybe, external coatings have to be more robust and are therefore especially expensive, so that some manufacturers decide to accept a few % loss of transmission and keep these parts uncoated.
Holger
Holger,
I am not aware of any modern binos that have uncoated objectives. (Doesn't mean they do not exist) The low cost binos selling for less than 50 Euro may have poor coating, are not"fully multi-coated" all not coated on some intrnal surfaces but they have coating on the objectives.
However, I do remember that when I ordered my 6in F8 AP refractor in the late 1980s I was given the option of having uncoated objective(first surface only). I think the explanation was that outter surface is exposed to dewing and airborne pollutants. Coating on the objective could be easliy damaged if it's not cleaned properly. And damaged coating could be more harmful than a few % transmission loss.( I think ~3-4% was mentioned). I elected to have my objective fully coated. I am not sure if that option is still offer by AP or any top APO manufacturers.(I can't imagine why not, it 'd lower the production cost) I defer to owners of newer AP, TMB and TEC scopes and other experts of optics coating for an update.
I'd think coating technology have been much improved in the past 16 years to make it more robust.
ERik D
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