• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

- The nominal luminous power of the binoculars: (1 Viewer)

Lee,

It seems that you have not understood the fundamental points debated in this thread so I'll recap on a few points.

Rico claimed in #1 to have invented a formula that shows that the luminous power of a binocular changes with magnification. Totally impossible by the laws of physics. In #4 and #6 I pointed out that brightness perception was totally different from luminous power and that magnification just made things more visible, and started to explain why in #8, pointing out that research by Leica (Leitz) and Zeiss by two measures had found that binocular perceived performance was proportional to magnification. This again showed his formula was nonsense. I even did the little test he requested in #10. Attempts to explain things further both in the thread and by PM were met with dismissal and insults.

I could go on pointing out details in this in other threads that show the flaws and contradictions in his
numerous posts, and his confusion is absolutely underlined in #33 that shows even he has lost track of what parameter his formula might refer too. The undeniable fact is, that it is none of them. It's total garbage.

As for the test he is requesting, that was published in 1943 by Berek as I mentioned at the start. I hope Holger doesn't mind me posting one plot from his paper on Berek's work that shows visibility is simply proportional to magnification in the luminance range he suggests.


David
 

Attachments

  • Screenshot_20200117-195541.png
    Screenshot_20200117-195541.png
    57.2 KB · Views: 34
Last edited by a moderator:
It seems to me that, while a reliable formula for this "luminous power", provided it can meet laws of physics, might be an interesting educational undertaking, it seems to me to actually prove nothing. We already have things like twilight factor, relative brightness, relative light efficiency to take a guess at low light performance. It seems to me that luminous power is more of the same.

There is nothing in the other mentioned indices of low light performance that takes into account variations in binocular quality. Unless one wants to promote the idea of quality making no difference. One has to think that by these measures a $25.00 discount store special with red lenses is the equal to a Swarovski costing $2,500.00. After all they all have the same twilight factor, relative brightness, relative light efficiency, and it appears would have the same luminous power. Who actually thinks the Swarovski (or any other quality binocular) would not win this sort of competition?

It might be useful to have something reliable like this, but with all due respect, as I see it, this is not it. A binocular has a finite amount of light energy to work with at any given instant. It can not produce more light to make the image brighter.
 
Last edited:
typo said:
Lee,

It seems that you have not understood the fundamental points debated in this thread so I'll recap on a few points.

Rico claimed in #1 to have invented a formula that shows that the luminous power of a binocular changes with magnification. Totally impossible by the laws of physics. In #4 and #6 I pointed out that brightness perception was totally different from luminous power and that magnification just made things more visible, and started to explain why in #8, pointing out that research by Leica (Leitz) and Zeiss by two measures had found that binocular perceived performance was proportional to magnification. This again showed his formula was nonsense. I even did the little test he requested in #10. Attempts to explain things further both in the thread and by PM were met with dismissal and insults.

I could go on pointing out details in this in other threads that show the flaws and contradictions in his
numerous posts, and his confusion is absolutely underlined in #33 that shows even he has lost track of what parameter his formula might refer too. The undeniable fact is, that it is none of them. It's total garbage.

As for the test he is requesting, that was published in 1943 by Berek as I mentioned at the start. I hope Holger doesn't mind me posting one plot from his paper on Berek's work that shows visibility is simply proportional to magnification in the luminance range he suggests.


David
Click to expand...

David
It seems that you have not understood the fundamental points of my post, Post 40 is concerned with two people who appear to think they are disagreeing but it seems to me they are not.

Lee
 
Last edited:
Troubador said:
A candle or other light source, whether viewed through 8x binos or 100x binos has the same brightness, as both you and Rico have said. But it will be more visible (to use Rico's phrase) through the 100x binos because its image will occupy a much larger proportion of the view and so (to use your words) will be perceived to be much brighter.

As far as I can see then, you and Rico are agreeing.

Lee
Click to expand...

In fact if the image of the candle is spread over a greater area of the retina by the increased magnification it will actually be less bright.

Lee
 
typo said:
...his formula was nonsense... It's total garbage.
Click to expand...
The fact that David has no choice but to insist on the "twilight factor" clearly indicates that he has not yet understood anything about the speech. .

Out of kindness I try to repeat the thing:

Leitz and Zeiss' research is indicated for ambient brightness values equal to or less than the moonlight (0.1 - 0.01 cd/m^2), and are unsuitable for twilight (20 - 1 cd/m^2) to which I refer.
 
Last edited by a moderator:
Troubador said:
In fact if the image of the candle is spread over a greater area of the retina by the increased magnification it will actually be less bright.
Click to expand...
The first principle of thermodynamics, or principle of conservation of energy, establishes that nothing is created and nothing is destroyed, but everything is transformed.
The intensity of the light remains the same, but that's not what we need to discuss. The increased amount of retinal receptors is increased in proportion to the square of the magnification. Which, together with the surface of the exit pupil, determine the nominal value of the "twilight power" (of the reading capacity of that type of ambient brightness).

Said as a metaphor, "twilight power" can be calculated as the flow rate of a water conduit. The diameter of the conduit is the aperture and the pressure is the magnification. The product of both, provides flow rate.
 
Steve C said:
...it seems to me to actually prove nothing. We already have things like twilight factor, relative brightness, relative light efficiency to take a guess at low light performance. It seems to me that luminous power is more of the same.
Click to expand...
Steve, there is nothing like this that you have listed. I know them all and the results indicate other characteristics.
Just try to compare each one (even in a mathematical way), for some format examples.



PS:
the funny thing, is that no one has ever tried seriously.
 
This is very likely my last post in this hair splitting exercise. I am not intending to directly compare your luminous power directly to twilight factor, relative light efficiency. I realize you are making a different sort of thing with luminous power. Regardless, I am of the opinion that luminous power is still meaningless, because, like twilight factor, it makes no provision for quality of the binocular. It seems to me that, and I repeat here, that it looks like a cheap discount store special with ruby red lenses that cost $25.00 will have the same luminous power as will a $2,500.00 Swarovski. Again I ask if you seriously believe that the two binoculars will provide equal performance in low light. I don't think anybody here will believe that, until you can demonstrate some reasonable provision in your formula that has provision for quality parameters in the binocular.
 
There has been a regrettable lapse by some members into using insulting remarks. You know who you are.
This is against forum rules and is not acceptable no matter what provocation is thought to have occurred.

Lee
Moderator
 
Steve C said:
I realize you are making a different sort of thing with luminous power. Regardless, I am of the opinion that luminous power is still meaningless, because, like twilight factor, it makes no provision for quality of the binocular.
Click to expand...
I also perfectly agree with your point, Steve. And I am also well aware that optical quality has a preponderant value, especially during twilight (which is the playing field of this formula).
So, no $ 25 binoculars can be compared to $ 2,500 binoculars.

Having said that, I believe that any formula should include a quality coefficient in order to return a consistent value.
So what you say is not in question.

But you must agree too, on at least two other fundamental points that I have already tried to express, but which seem not to have been adequately understood.

1 - this formula is set up at the simplest level, to be easy to use and to give a rough idea of ​​the various formats, considering all the rest of the factors not included, as "equal for all" (same optical quality, same transmission , same user, same ambient brightness, etc.).

2 - If the aim is to constitute a complete formula that is actually consistent in any case, in addition to the value of the transmission, a whole series of other factors must be taken into account and entered precisely.
For example, the difference between the individual vision and the way it behaves in the various levels of ambient brightness, or the retinal sensitivity or the opening of the iris, will be other fundamental factors to be considered obligatorily every time. And of course, all this would complicate the drafting of the formula, up to the levels of splitting the hair into 12000 pieces, and not just 4.

So, I don't find that there is anything wrong with using a simplified formula, which still works in order to have a "rough idea", simply using it with a grain of salt.
 
Rico70,
Making formulas and theories is one thing, but proof comes from experiments. Have you already planned simple experiments to proof your point? I am curious.
Gijs van Ginkel
 
Rico70 said:
I also perfectly agree with your point, Steve. And I am also well aware that optical quality has a preponderant value, especially during twilight (which is the playing field of this formula).
So, no $ 25 binoculars can be compared to $ 2,500 binoculars.

Having said that, I believe that any formula should include a quality coefficient in order to return a consistent value.
So what you say is not in question.

But you must agree too, on at least two other fundamental points that I have already tried to express, but which seem not to have been adequately understood.

1 - this formula is set up at the simplest level, to be easy to use and to give a rough idea of ​​the various formats, considering all the rest of the factors not included, as "equal for all" (same optical quality, same transmission , same user, same ambient brightness, etc.).

2 - If the aim is to constitute a complete formula that is actually consistent in any case, in addition to the value of the transmission, a whole series of other factors must be taken into account and entered precisely.
For example, the difference between the individual vision and the way it behaves in the various levels of ambient brightness, or the retinal sensitivity or the opening of the iris, will be other fundamental factors to be considered obligatorily every time. And of course, all this would complicate the drafting of the formula, up to the levels of splitting the hair into 12000 pieces, and not just 4.

So, I don't find that there is anything wrong with using a simplified formula, which still works in order to have a "rough idea", simply using it with a grain of salt.
Click to expand...

Rico,

One of the problems I see with your posts is a seeming contradiction which does not help with understanding. Points one and two, quoted above seem to me to be illustrative. Point one says your desire is for a simple and easy to use formula. Fine, that is a good thing. Then comes point two. The formula, to be complete, needs to not only include transmission, but other optical variables as well. How many manufacturers would give out the figures needed for transmission and other optical variables? I bet that would be pretty difficult at the best. You then introduce the variables that will occur between vision of different users. Would not somebody have to go to a very good Ophthalmologist and get a specialized eye exam that will produce figures usable in whatever formula? Seems like the cost of the eye exam might exceed the cost of a binocular. I doubt insurance would pay for it on the basis of somebody wanting a binocular. How many average binocular users would have the mathematical acumen to compute the luminous power with all of those things accounted for? It appears you take your own quest from 4 pieces in point one to the 12,000 pieces in point two. Pretty well precludes a simple formula as far as I can see. But hey, I am not a mathematician or optical expert, just a simple farmer with a post graduate degree in Biology.

Maybe it is time for you do do a post computing luminous power as your formula stands. Just a couple of configurations. Pick your own configurations and manufacturers. Until you can begin to come up with some reasonable proofs of your theory, I feel I am forced to remain skeptical.

With all due respect, you are right about taking it with a grain of salt. Add the grain of salt needed for all of the other variables and pretty soon we are holding a whole bag of salt. Good luck in getting rid of a lot of salt grains. Maybe you will prove my skepticism unfounded.
 
I'm sorry Steve, maybe it's me who can't answer you adequately, but I certainly can't understand if your skepticism is addressed to me or to the formula.
Your point has always been that of "contradiction of my posts that does not help to understand", but honestly I do not see any contradiction, neither in me nor in the formula. And it is not even so clear which points you would not have understood yet.
Steve C said:
One of the problems I see with your posts is a seeming contradiction which does not help with understanding...
...Good luck in getting rid of a lot of salt grains. Maybe you will prove my skepticism unfounded.
Click to expand...
the grain of salt is simply to use this formula, comparing only binoculars with the same or very similar optical quality, same transmission, same environmental and individual situations, etc.
But we don't need a degree to understand this.

Or am I wrong?
 
Last edited:
Gijs van Ginkel said:
Making formulas and theories is one thing, but proof comes from experiments. Have you already planned simple experiments to proof your point?
Click to expand...
Certainly yes, Gijs. I have also done various experiments and that's why I say that the formula works. The point is directly planned in the formula itself, which does not serve to give an absolute value, but rather an equality or a difference between two formats in comparison.

For example, the value of the "twilight factor" for 10x35 and 7x50 is the same (18,7 tf), but the 10x35 is actually an all-rounder format unsuitable for twilight, while the 7x50 is a purely twilight format.
Using "pln" formula, this substantial difference becomes evident, since in practice the 7x50 (360 pln) has a much higher capacity to "brighten up the view in the twilight" than the 10x35 (120 pln). I don't know if it's three times as much, but the difference is clear.

Maybe it is not clear what it means to "brighten up the twilight"?
 
Last edited:
Rico70, post 57,
Although this is correct according to your formula, there is one serious problem:
-1- suppose both binoculars have exactly the same transmission curve, they do have a large difference in exit pupil and I can assure you that there will be a big difference in observed brightness, whatever your formula will say and that is only dependent on the difference in size of the exit pupil.
If you really want to test your hypothesis than you have to find two binoculars with exactly the same transmission spectra and exactly the same exit pupil, but a big difference in magnification. In order to check it you need a perfectly evenly illuminated white surface (large enough) and a calibrated light meter to measure the output of both binoculars and compare both signals.
Gijs van Ginkel
 
Rico,

The skepticism is directed at the formula, at least at the notion of a complete version. It seems if it is to be simple it won't prove much. Taking it with a grain of salt is what I'm doing. We already have to take things such as twilight factor, light efficiency, and relative brightness with grains of salt. Add another grain of salt for each of what what I see as too many variables that need to be accounted for was where I got the bag of salt.

I quote your point two below...

"If the aim is to constitute a complete formula that is actually consistent in any case, in addition to the value of the transmission, a whole series of other factors must be taken into account and entered precisely. For example, the difference between the individual vision and the way it behaves in the various levels of ambient brightness, or the retinal sensitivity or the opening of the iris, will be other fundamental factors to be considered obligatorily every time. And of course, all this would complicate the drafting of the formula, up to the levels of splitting the hair into 12000 pieces, and not just 4."

Perhaps I misunderstood that your aim is not a complete formula, but to stay simple, as in four pieces of the puzzle. It seems to me that to be complete, you have the 12,000 pieces to deal with. I guess i see no point in a simple formula we have to apply a series of guess based on personal experience as to what sort of pln number we need in which kind of binocular to get where we need to go. Binocular purchases involve a string of guesses to get to where we want to be. I have a hard time seeing where more guessing, i.e. taking additional factors with a grain of salt, helps much.

I have said my say and leave you to your endeavour. Good luck with the process.
 
Warning! This thread is more than 4 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Similar threads

kimmik
Light throughput equation
2 3
Replies
48
Views
4K
kimmik
kimmik
J
Formulas and examples for resolution gain according to Köhler and Leinhos
Replies
1
Views
902
Sterngucker
S
yarrellii
Vixen @Six 6x18: quirky and surprising pocket binocular
2
Replies
25
Views
3K
has530
has530
C
Steiner Navigator 7x30 - with "Auto Focus"
Replies
13
Views
3K
Canip
C
T
Testing Binocular Stability
Replies
6
Views
3K
Patudo
P

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Back
Top