wilash
Fairy Godmother
Reged: 09/30/03
Posts: 5746
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Unfortunately, Joad has pointed out, there are two problems. The physical problem of the optics and the problem of how the human visual system processes image information.
As far as optics go, the answer is not in the aperture, but the exit pupil. Systems with the same exit pupil form images of equal brightness (but not necessarilty equal magnification or equal resolution). An optic system having two barrels or one does not change brightness, and so binoculars are not "brighter" than telescopes. (If you want to talk about issues of transmitance, then binoculars can have a disadvantage.)
How we perceive the information from an optical system is far more complex. But basically, the human visual system is far more efficient when using two eyes. How you perceive this can vary beween people because it is not simply a physical problem. I personally have never thought images were "brighter" when using two eyes compared with one. I do percieve an increase in resolution. I know others "define" their experience differently. And that is one problem of trying to "define" human vision, it can only be a statistical model based on a sample response.
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sftonkin
sage
Reged: 02/25/04
Posts: 395
Loc: Kent, UK
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Quote:
Unmathematical, unreliable and unrepeatable results pop up in testing based on PERCEPTION!
Indeed so. And it gets worse: Visual perception can be based on EXPECTATION. Given that all the actual visual processing happens behind the retina, it becomes incredible that we have the wit to subject so much of the physiological visual system to some species of scientific analysis.
In this context, you may be interested in Arthur Zajonc's Catching the Light: The Entwined History of Light and Mind . Superb read.
More importantly, I think you have shown up how attempts at brevity (a disease from which I increasingly suffer in this "age of the sound-bite") in the face of seeming requests for quick answers, can be potentially misleading. Thanks.
(And this episode, I suggest, is but one reason that you need to get that book done!)
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Stephen
Hindsight: The only truly diffraction-limited system
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johnno
scholastic sledgehammer
Reged: 05/03/04
Posts: 807
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[quote "Were you born stupid, or did you just get that way?"
Hi Bill,
I love that,
My response is similar,
I usually say.
"Were you born stupid,or do you work at it"
BTW,Thanks for a very interesting Thread,by all contributers
Have a nice Xmas Bill,and
All members here.
Regards.John
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LunaC
super member
Reged: 10/06/06
Posts: 198
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Quote:
APERTURE alone has no relationship to focal ratio .
Sure it does on the order of FNumber/f 
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wilash
Fairy Godmother
Reged: 09/30/03
Posts: 5746
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Quote:
Quote:
APERTURE alone has no relationship to focal ratio .
Sure it does on the order of FNumber/f
You mean f/f-number.
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LunaC
super member
Reged: 10/06/06
Posts: 198
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Quote:
Quote:
Quote:
APERTURE alone has no relationship to focal ratio .
Sure it does on the order of FNumber/f
You mean f/f-number.
Direct or inverse, it is still a relationship  
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BarrySimon615
scholastic sledgehammer
Reged: 03/01/04
Posts: 964
Loc: New Orleans, LA
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Hi guys, this has been an interesting thread. Somewhat of a familiar path though, that many of us have been down before. My personal experience with testing of my own binouculars both past and present and telescopes past and present lead me to conclusions that support both basic premises. That is - that two objectives working in tandem will give you more than what you would get with one objective (same diameter) at the same magnification. HOWEVER you will rarely use a telescope with the same objective size at the same power and those low powers are such that you likely are going to notice differences between mono objective/eye use and bino objective/eye use less than you would at magnifications that are closer to the performance limits of a particular objective size. Personally I see very little dramatic gain in brightness comparing like size binoculars and telescopes. To me the real binocular advantage is the correctly oriented view and the two eyed use which helps give a pseudo 3 dimensional view of objects such as the Moon and M-27, the Dumbbell Nebula. The reality of the 3 dimensional perception is another topic for argument. Like the bee that should not be able to fly, science would tell you that it is impossible with binoculars at distances beyond about 20 feet yet some claim that they get a 3 dimensional view at objects observed many light years away.
The other thing that really tends to influence the results is the disparity in the number of additional elements and restrictions in the light path of binoculars that tend to pull that 40% increase in physiologic aperture increase down.
I think we should all just take comfort in the fact that telescopes and binoculars are like golf clubs - different clubs have different uses, uses that they all excel at.
Merry Christmas!
Barry Simon
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sftonkin
sage
Reged: 02/25/04
Posts: 395
Loc: Kent, UK
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Just a couple of things:
#1. AIUI, the non-aerodynamic bumble-bee is the stuff of urban legend.
#2. You can get false steropsis with one eye! (Look at a photograph through a narrow tube.)
And a cool yule to you as well, Barry!
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Stephen
Hindsight: The only truly diffraction-limited system
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KennyJ
Reged: 04/27/03
Posts: 10453
Loc: Lancashire UK
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First of all , may I take this opportunity to apologise for my " deliberate mistake " in a previous post to this thread ! :-)
What I MEANT to say was that , in theory , the same focal ratios can be achieved by an infinite variety of combinations of aperture and eyepieces of certain focal lengths .
I still think that there is a kind of " missing link " of knowledge ( or at least easily found or easily understood recognition ) of the differences between mono and stereo vision through magnifying instruments .
What I mean is , what actually occurs :
1. Between eyes and brain
2. In the brain itself
and
3. How that information is translated ( into personal visual impressions which can be conveyed to others via normal day to day language )
The " 3D impression " which Barry mentions is perhaps a good example of how human perception can appear to conflict with " scientific fact " .
Merry Christmas everyone !
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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Joad
Wordsmith
Reged: 03/22/05
Posts: 12028
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"3. How that information is translated ( into personal visual impressions which can be conveyed to others via normal day to day language )."
Ah, here we are in my area of expertise, and the situation is just as messy; probably messier (not Messier!). Ordinary language is packed with broadly general terms that serve for everyday communication, but one's man's "tack sharp" is another's "bloated stars." I suppose it would be possible to train viewers professionally (as, say, wine tasters are trained and are accordingly able to share a precise and professional set of terms to describe various flavors and tastes) so that specific terms can be matched to specific visual phenomena, but since professional astronomers haven't really spent much time actually looking through telescopes for many years now, it would have to be the amteurs who might band together and "norm" what they see around a common highly specific vocabulary. It would an interesting sort of training procedure, involving side-by-side viewing through the same instruments and comparing photographs together--just as during an eye exam the opthamologist has a precise set ofnormed images that he can ask you about.
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V.A.
sage
Reged: 05/14/05
Posts: 281
Loc: Ontario, Canada
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dare i say that even our perception of what is a 3D image can be wrong.
true 3D vision requires there to be a minimum paralax angle created from one eye ( or obgective)to the other. distances for this to happen are in nearby terrestial views.
when i first started looking through binoscopes i had a strong impressions of what i thought was a 3D image, i remember staring a single star in an almost empty fov, that star was suspended in midspace. but the real definition of 3d is can you tell the distances? or which star ,galaxy or whatever is farther ? i certanly can't, infact looking at it carefully everything seems to lie on the same plane. so there is a phenomenon powerful enough to cause us mistakenly interpret it as 3D.
for me this false 3D effect through a binoscope is highly dependent that both sides be optically identical, and all adjustments, including focusing be as accurate as possible. even the magnificatio seems to have an effect on this.
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10" binocular telescope
Oberwerk 7x50 Mariner
tv 24pans , plossl's and 12mm t4s
6.5 mag. dark skies
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LunaC
super member
Reged: 10/06/06
Posts: 198
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Just ask yourself this question: If you close one eye while peering through your bins, does the image lose brightness? Now pose the same question in regard to resolution.
Edited by EdZ (12/26/06 08:19 AM)
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12793
Loc: Cumberland, R I , USA42N71.4W
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Quote:
Just ask yourself this question: If you close one eye while peering through your bins, does the image lose brightness? Now pose the same question in regard to resolution.
Your first question was answered by explanations already posted in this thread, and it is yes. This second question re: resolution, as posted, is left quite open-ended. No attempt by the poster to suggest he has an opinion on the subject. Oh well, since it is on topic, I will address it by reference, since we have already visited this topic in the past.
This problem was addressed in the link above to a comprehensive discussion of binocular summation. I highly recommend you follow the Best Of links to the discussion on Binocular Ssummation.
A few excerpts from that discussion on binocular summation;
What becomes of resolution in a binoviewer or binocular? It certainly is not halved in the binoviewer and then regains 40% from summation. Most empirical reports seem to indicate resolution may still be based on the original aperture. I have not had the benefit of using a binoviewer to test this. I will someday. But there is evidence that tends to lean towards agreeing with this. We do not get a gain of double the resolution. Some users have noted an increased acuity, meaning the ability to see the resolution at a lower power. This agrees with what has been found in vision studies in that some individuals have been measured to gain one line on a Snellen chart.
But regardless, the resolution of a binocular is always equal to or even very slightly better than just using one lens at the same magnification. This I have tested on double stars and on a USAF resolution chart.
The 8" scope with binoviewer still provides at a minimum the resolution of an 8" scope and possibly slightly better. Binocular summation cannot increase or decrease the size of the Airy disk, but it does cancel out a slight amount of noise, so it improves your accutance. This explains why resolution is more in line with whatever size scope you started with and not the reduced effective aperture (due to the binoviewer).
For the person that experiences a lot of "noise" when mono viewing, binociular viewing could provide a significant benefit. Viewing with two eyes cancels a lot of noise. When your left eye has a floater in the way, your right eye may be providing a clearr view, canceling the noise of the left eye floater.
Resolution stands to realize gains. We know resolution improves somewhat with binocular vision. My resolution chart tests showed binocular vision improved resolution by 10%. Eye exam tests sometimes show 20%-25% improvement, not full resolution but blur detecction. But both of those are very high contrast. We don't know that contrast improves, and in fact, if light decreases contrast decreases. So what probably happens here is high contrast objects may show some improvement in resolution (when viewed with binocular vision), but low contrast objects probably will not.
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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LunaC
super member
Reged: 10/06/06
Posts: 198
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Quote:
Your first question was answered by explanations already posted in this thread, and it is yes. This second question re: resolution, as posted, is left quite open-ended. No attempt by the poster to suggest he has an opinion on the subject. Oh well, since it is on topic, I will address it by reference, since we have already visited this topic in the past.
No opinion was rendered due to the rhetorical nature of the post. Basically, it is a 2 second test everyone that answers the question for them.
As for brightness, I find no difference personally. Just take bins out of the equation. Is the world a brighter place with one eye closed? I can resolve more with two eyes open but the image is no brighter. I notice this every time I go to get an eye exam.
The brain is a wonderful little device though so I would notargue with a person that says that they see a brighter image when using bins
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LunaC
super member
Reged: 10/06/06
Posts: 198
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Quote:
for me this false 3D effect through a binoscope is highly dependent that both sides be optically identical, and all adjustments, including focusing be as accurate as possible. even the magnificatio seems to have an effect on this.
This reminds me of a few situations where I found myself listening to cd or two and then only to realize a day later that I had the preamps mono switch pressed in. I assume we do that same with optics as we do with audio.
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KennyJ
Reged: 04/27/03
Posts: 10453
Loc: Lancashire UK
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I must be one of those rare , minority species , who actually DOES perceive seeing a DARKER image when I close one eye , with or without binoculars .
The drop off in perceived brightness is not the only difference I notice either .
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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ChrisR
professor emeritus
Reged: 02/11/05
Posts: 518
Loc: Washington
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So if you cover the objective lens of one barrel on a binocular, does this mean you are using diet binoculars? 
I just hate it when I get fat eyeballs. 
Peace,
Chris
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Journeyman Optical Technician
Amateur Astronomer.
All around good guy
Orion, StarMax 127
Canon, 12x36 IS
Minolta, 8x25 WR
Halco, 7x50
Nippon Kogaku, Micron 7x35
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BillC
on a new path
Reged: 06/04/04
Posts: 2129
Loc: Washington, USA
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>>>Just a couple of things:
#1. AIUI, the non-aerodynamic bumble-bee is the stuff of urban legend.<<<
Stephen, Kenny:
I keep hearing about the Brits "dry" sense of humor. Don't you think we can do that over here? 
But, there are still a couple more points.
First, I have attended 6 colleges and universities, and virtually every time I have heard the BEE MYTH, it has come from some academician in a position of illustrative authority, but who believed the story and passed it on as fact. In addition, I’ll wager that more minds have changed due to the internet than the reading of scientific documentation. 
Secondly, one need not go back to far to come up with any number of scientific FACTS that weren’t. For example, while doing a paper on the development of the automobile, in high school, I came across a paper written near the turn of the last century that stated man could not travel in an open-topped conveyance at a speed greater than 25-30 miles per hour. Should they try to do so, the author said, the air would rush past the nose and mouth at such a speed that the body would not be able to—because of the weakness of the lungs—draw the air in.
Finally, Today, Darwin has almost attained sainthood in the eyes of some scientists. What most don’t know—usually because Darwin is much easier to adore than read—is that HE was bewildered by many of his contradictory findings. The first part of chapter 7 in On The Origin of The Species is most enlightening. 
Just a thought, and a GREAT new year to all,
Cheers,
Bill
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Joad
Wordsmith
Reged: 03/22/05
Posts: 12028
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Kenny,
I do not think that I perceive a difference when I close one eye in daytime vision, but when I am viewing with the big binoculars at night and close one eye the difference is dramatic. Binocular vision summation is certainly working for me there. I not only lose brightness but I also lose the ability to focus my eye well (note that I am emphasizing my subjective physiological experience here, not objective optical laws). It is far less tiring on my eyes for both to work together in focusing at the oculars.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12793
Loc: Cumberland, R I , USA42N71.4W
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LunaC wrote:
Quote:
Just ask yourself this question: If you close one eye while peering through your bins, does the image lose brightness? Now pose the same question in regard to resolution.
Basically, it is a 2 second test everyone that answers the question for them.
As for brightness, I find no difference personally. Just take bins out of the equation. Is the world a brighter place with one eye closed? I can resolve more with two eyes open but the image is no brighter. I notice this every time I go to get an eye exam.
Unfortunately, that simple test for resolution is not rigorous enough to show the differences that DO exist. Oftentimes we see people suggest a simple way to test for something and many times those simple tests really don't test to the intended question. A reference back to the "Best Of" thread regarding this topic will give some better indications of the rigourous testing required to show these differences. The brightness issue thru one unaided eye only that you describe here is exactly the same issue that was raised earlier (and explained) in this thread. Read that explanation to understand why that simple test doesn't work to show differences in brightness.
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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