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Most overrated feature for binoculars? (1 Viewer)
- Thread starter lvn600
- Start date
Wehr
Well-known member
postcardcv said:
Have you ever really observed with your Leica? Don't think so - you should have noticed the stunning difference in 100% of the time - and - to get a brighter image with binocs than with just your eyes is completely impossible. It is just a self-deception.
It all depends on experience behind the eyepieces.
Walter
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Wehr
Well-known member
Kevin said:
As you mentioned - you are surely blind. :eek!:
If you don't see the difference, it doesn't make sense to pay the money, but if you have little observing experience at this moment, you will see the difference sooner or later. It all depends on experience behind the eyepieces.
Walter
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Wehr said:
Walter,
You are absolutely right there. It's theoretically impossible to get more than 95-96% of the brightness through the very best binocular, but in practice it can sometimes be experienced as a result of improved darkness seeing because the eyecups of the binocular block stray light from the sides.
Patric
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hornet
Well-known member
lvn600 said:
Celebrity endorsement. Or anyone else's endorsement really.
As most binocular threads on BF prove, no opinion is absolute (not even a celebrity's). No matter how much you're spending, you really should try for yourself before you buy.
Having said that, ironically that I use the bins that Bill Oddie (a UK birding celeb) has been promoting for years!
dbradnum
Well-known member
Have to say that one or two of the suggestions on this thread made me laugh out loud! Without meaning any offence at all, I can't believe anyone would think
Guess it goes to show that different people have different priorities, and that when evaluating optics you should always try things out before you buy, against your criteria, not anyone else's! What one person thinks is fantastic might be fundamentally deficient in another's opinion.
- wide field of view
- close focus
- waterproofing
Guess it goes to show that different people have different priorities, and that when evaluating optics you should always try things out before you buy, against your criteria, not anyone else's! What one person thinks is fantastic might be fundamentally deficient in another's opinion.
xenophobe
Well-known member
Wehr said:
Funny, because at least HALF of the experienced AND inexperienced viewers that look through my 12x50 Trinovids say they're just too bright. I agree, in normal daylight viewing the first few seconds you look through them, the knee-jerk reaction is to look away from them. Once your pupils dialate, then the view is quite nice indeed.
Not really self-deception. Just a matter of the ambient brightness in your general viewing area and the relative brightness of the particular area you are viewing. Example, looking at the darker underbrush of a well lit area, your eyes won't be absorbing as much light as if you were looking at the background with your bare eyes. If you look at a brighter area with your glass, you are indeed taking in more light than you would without the binoculars.
Wehr said:
Well, there is a little more to it than that really. Let me give you a couple of examples:
With astronomical equipment, it is a well known fact that you can see many objects through magnification that cannot be seen with the naked eye. Higher magnitude stars are just one example.
Now, if you take your binoculars, and place a piece of white paper behind the eyepiece outside in daylight, is the projected exit pupil that you see "through" the paper brighter than the surrounding background that is not being magnified ?
Or, take a simple magnifying glass as we did when we were kids, and bring the image of the sun to a point. Is it brighter, more distinguishable than just the background sunshine ? Of course it is.
But, we are not "producing" more light than is already available, that is a fact. What we are doing is "concentrating" the available light into a smaller area, which in effect (via magnification) is restricting that light to a specific area, making it more "intense" than it would appear via the naked eye. Spotlights, flashlights, car headlights, etc. work on this same principle using reflective paraboloids, with some high-intensity "driving lights" actually using simple magnifying lenses. "Throughput" and strehl values are really just one part of the issue, as is magnification of the available light, optic design, coatings, and so on. Since it is not "fully multi-coated", a plain glass magnifier obviously reflects back alot of the received light, but that does not hinder the intense magnification and concentration of what does actually pass through the lens.
Just a thought........
Bryant
solentbirder
Well-known member
lvn600 said:
Roof prisms !
(well someone had to say it)
Robert Ellis
Larus marinus
solentbirder said:
I agree. The only roof I would ever consider would be the EL, and ONLY because it handles like my porros. I can get my hands all the way 'round one like I can with a porro. The bridge in a roof gets in my way, and I hate holding the binoculars with my fingertips. You wil probably not, however, ever come across me using an EL because they are ridiculously overpriced, I don't care how good they are. I am not spending in the neighborhood of $1500 on a pair of binoculars.
Hmm... If anyone wanted to give me a pair of 8x32 ELs I'd use them no doubt on occasion, any takers?
Wehr
Well-known member
Bryant said:
Bryant,
you are mixing up things. Otherwise a 12x50 with the smaller exit pupil (higher magnification) should be much brighter than the exit pupil of a 8x50 with less "light concentration". This is definitely not the case. Light gathering in astronomical star observation is completely different.
Walter
Wehr said:
Okay, let's look at that 50mm objective in comparison to say a 30mm objective. Which generally has the "brighter" view, assuming both have the same diameter exit pupil ? Which has the most "light grasp" relatively ? Which of the two will pull out fainter magnitude stars ? Remember that a higher magnification is going to have the narrower field of view, so perhaps less "perceived" brightness due to the field "area" involved, but when all is said and done, there are only 2 kinds of light.....either refracted (source) light or reflected (secondary) light. And in either case, optical magnification concentrates both types. A low power wide-field binocular will more often give the brighter "perceived" view because of the area of the field involved. It is simply "seeing" more light than a narrower field (higher power) binocular. Then again, we have to take into consideration the effects (constriction) on the pupil of the eye from the incoming light which can vary from one observer to the next. The exit pupil of the binocular is not nearly as important as how the entrance pupil of the observer relates as a result of what the eyes are being provided. Looking through a 7mm exit pupil vs. looking through a 3mm exit pupil alone does not tell us which one will appear brighter than the other, especially so in bright daylight. There are other considerations to make as far as resolution and contrast, though the former is not as important at the low magnifications of most binoculars. Stars against a dark sky are another matter, as you point out, but only in that the eyes entry pupil is able to dialate larger and make better use of a larger instrument exit pupil. 7mm exit pupils during bright daylight are more often than not wasted because of the eyes inability to put them to optimum use. Only when the eye pupils can contract to the full 7mm will a 7mm exit pupil be of real benefit (speaking optically rather than ergonomically). In bright daylight, that is just not the case.
Bryant
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Grousemore
Senior Member
dbradnum said:
The question was... "Most overrated feature..."
I don't think that any of the quotes you laughed out loud at were referring to your criteria of 'significant advantage'
Wehr
Well-known member
Bryant said:
Bryant,
speak of "effective exit pupil (including the eye's pupil)" and you can abbreviate the explanation. But in gathering light a 7x50 and a 12x50 are exactly the same. There is no light concentration effect by magnification. 12x magnification is only showing you the same object through a larger angle, so that the eye can see objects, which are not visible with 7x.
<<Now, if you take your binoculars, and place a piece of white paper behind the eyepiece outside in daylight, is the projected exit pupil that you see "through" the paper brighter than the surrounding background that is not being magnified ?<<
The projected exit pupil will never be as bright as the original (for example the sky). That's we are discussing about.
>>Or, take a simple magnifying glass as we did when we were kids, and bring the image of the sun to a point. Is it brighter, more distinguishable than just the background sunshine ? Of course it is.<<
We are not comparing the brightness of the sun with that of the surrounding, but the brightness of the original sun with that of the observed or projected sun. In all cases the original will remain brighter. With a simple magnifying glass you concentrate energy in the focus, but at this location you never get an image of the sun.
I am pretty sure, that we have a big misunderstanding. And I am also sure that you know the truth as I do. Please think about it again.
What I'm saying is, that there is no (passive) optical instrument, that can offer you more light than is in the original object. You can only make things bigger and overcome the eye's limits of resolution and light gathering performance. Larger openings increase resolution performance of the naked eye and compensate the darkening we get from magnification.
Walter
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I guess we'll just have to agree to disagree on a few of these points Walter, though for the most part I think we are on the same page here.
First of all, the projected image through a glass is creating a more intense "reflected" image, as in the example of the magnifying glass and the paper. When you compare the concentrated image on the paper to the surrounding reflected light on the paper outside the magnified area, it is indeed providing a brighter "reflection", but this does not mean it is brighter than the original light source. That is the premise of my arguement here in "actual brightness" vs. "perceived brightness".
1. There is no light concentration effect by magnification.
Again, it is a simple matter of taking a piece of paper outside with your binocular and projecting the exit pupil onto the paper. Is that concentrated "spot" brighter than the other light passing through the paper ? It's a matter of taking the light at one end of the light-cone (in front of the objective) and concentrating it at the other end (exit pupil). That is what magnification does. It "concentrates", but it does not "enhance".
2. The projected exit pupil will never be as bright as the original (for example the sky).
See my response to #1 above. The "concentration effect" makes the light "appear" brighter at the reflected plane. I agree that the reflected image is not as bright as the original light source. It is just "perceived" as being brighter.
3. With a simple magnifying glass you concentrate energy in the focus, but at this location you never get an image of the sun.
But you can get an image of the sun, albeit too bright to really distinguish. Do the same thing then with the magnifying glass and any indoor light bulb, and you can easily bring it to focus using just the magnifying glass and a piece of white paper as a screen. That image will also "appear" brighter on the paper, otherwise it would be completely indistinguishable.
4. You can only make things bigger and overcome the eye's limits of resolution and light gathering performance.
By "light gathering performance", are you referring to the concentration of light ? I believe you are.
As I stated in my first response, I agree that no passive optical instrument is going to "create" more light than is already present. But a good analogy here might be what is used in the difference between "true field of view" and "apparent field of view", with true brightness and apparent brightness being where most people get the perception that they are seeing more than is actually there. With TFOV vs. AFOV, what you are "seeing" is also much less than what you "perceive", angle-wise. I think a similar effect or phenomenon carries over to image brightness.
Just my opinion.
Bryant
First of all, the projected image through a glass is creating a more intense "reflected" image, as in the example of the magnifying glass and the paper. When you compare the concentrated image on the paper to the surrounding reflected light on the paper outside the magnified area, it is indeed providing a brighter "reflection", but this does not mean it is brighter than the original light source. That is the premise of my arguement here in "actual brightness" vs. "perceived brightness".
1. There is no light concentration effect by magnification.
Again, it is a simple matter of taking a piece of paper outside with your binocular and projecting the exit pupil onto the paper. Is that concentrated "spot" brighter than the other light passing through the paper ? It's a matter of taking the light at one end of the light-cone (in front of the objective) and concentrating it at the other end (exit pupil). That is what magnification does. It "concentrates", but it does not "enhance".
2. The projected exit pupil will never be as bright as the original (for example the sky).
See my response to #1 above. The "concentration effect" makes the light "appear" brighter at the reflected plane. I agree that the reflected image is not as bright as the original light source. It is just "perceived" as being brighter.
3. With a simple magnifying glass you concentrate energy in the focus, but at this location you never get an image of the sun.
But you can get an image of the sun, albeit too bright to really distinguish. Do the same thing then with the magnifying glass and any indoor light bulb, and you can easily bring it to focus using just the magnifying glass and a piece of white paper as a screen. That image will also "appear" brighter on the paper, otherwise it would be completely indistinguishable.
4. You can only make things bigger and overcome the eye's limits of resolution and light gathering performance.
By "light gathering performance", are you referring to the concentration of light ? I believe you are.
As I stated in my first response, I agree that no passive optical instrument is going to "create" more light than is already present. But a good analogy here might be what is used in the difference between "true field of view" and "apparent field of view", with true brightness and apparent brightness being where most people get the perception that they are seeing more than is actually there. With TFOV vs. AFOV, what you are "seeing" is also much less than what you "perceive", angle-wise. I think a similar effect or phenomenon carries over to image brightness.
Just my opinion.
Bryant
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Bryant said:
Bryant,
That matter I have discussed earlier in another thread. My answer is: EVERY binocular with the same exit pupil has the same brightness providing the light transmission is equal undependent of aperture or magnification.
BUT that isn't the same thing as the light grasp, and that is the big confusion. People mix-up relative brightness to light gathering power.
The same exit pupil ALWAYS means that the light amount per area is equal providing the same light transmission value. Compare an equal quality 5x25 to a 10x50 or a 10x40 to a 20x80 with the same appearant FOV against an even coloured wall. Or a 10x50 to naked eye looking through a 5mm hole. (In this case the naked eye through a 5mm hole will be brighter than even the best 10x50 because of 100% light transmission)
If you look at an big even coloured wall with the naked eye at 10m distance, and then move to 5m, the wall doesn't become brighter because you approuch it. That is completely equivalent to look with a 10x40 and change to a 20x80. In both cases the eye pupil/exit pupil is the same undependent of distance/magnification.
Regards, Patric
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