1978 replies to this topic

[Masonry00]

Visual training does not increase the sensitivity of the retina. This is the point which must be refuted to Jon. 

 

By hypothesis, if you only live at night and sleep during the day for 40 years, perhaps your biology could undergo some slight modification and increase your retinal sensitivity.
But that's not the case for you and not even with Jon (and others).   

 

 

Henry 

I believe it is possible to train yourself to make your retina more sensitive.

 

Even if you limit the definition of "retinal sensitivity" to the electrical and chemical activity that occurs directly in and behind the retina, I think it's possible to train yourself to increase the chemicals that increase retinal sensitivity.

 

Perhaps more important from a functional perspective is that retinal sensitivity should include the part of the nervous system that transmits and interprets those signals. A lot of visual signals are transmitted to the brain where the perception processing simply ignores them, sometimes because the signal is below the threshold at which it processes it, and other times it fails to process them for other reasons. By training yourself you can change the behavior of the way the signals are processed which can cause you to "see" things that previously would not be visible.

 

Human vision is amazingly complex, and we often fail to appreciate just how complex it is because we are often told the eye is like a camera which is not really true once you learn how vision actually works. The similarity (with a camera) pretty much ends after the light is focused onto the retina. 

[gwlee]

Without going into the more complex details of mathematics and science, as we can all see, there are various "indices of merit" to calculate the function of binoculars in a simplified way.
One is the one you mentioned, but there is also the crepuscular index (by A. Kuehl - taken up in 1957 by H. Koehler and R. Leinhos, of Zeiss), the index of A. Adler, the index of C. Fankhauser and an index for the brightest twilight (civil and half of nautical). 

 

Now, each of these index uses the magnification and aperture data (this to simplify), because when the magnification value is also present, the aperture data "automatically" becomes the exit pupil data (which is what it takes).

So, we remember always the exit pupil is the only luminous data of the binoculars (even in these cases). 

 

But what often escapes most users is that each index can only classify binoculars for a specific task or a narrow luminance range. For example, twilight index of Zeiss is only useful for the luminance conditions of astronomical twilight. But most likely, due to the difference in individual retinal sensitivity, each of us could consider one index more appropriate than another, in similar situations. 

 

The Adler index, seems to work more for night stellar observation. And doing two simple calculations, the results of the 3 binoculars you mentioned become:

8√32 = 45, 10√25 = 50 and 10√50 = 70. 

 

I don't know if one or the other index is more correct or not for looking at the stars, but simply based on the individual and the situations (sky, objects, quality of the binoculars, etc.), it could be more or less congruent. 

Yes, there are several well known models, each has its proponents, the accuracy of each model is somewhat application dependent, most of them produce similar rankings, and none are perfect. As an experienced observer writing for a well respected astronomy publication, Bishop is offering his opinion about the most suitable model for binocular astronomy. 
 

In running the numbers for my binoculars using different models, I get different numbers, but similar rankings that more or less match my test results. I find the Bishop Index as accurate as any for my purposes (binocular astronomy) and a bit easier to use. I am wondering what other experienced binocular observers think of it. 

[Fiske]

Henry,

 

The two views accurately illustrate what I saw in Melotte 20 with the 10x25 masked versus the 10x50 full aperture view. The views are based on limiting magnitude estimates from actual observations made on the night of Thursday 9 December.

 

What's more, at your suggestion, this evening I observed the open cluster NGC 1981 in Orion with the Vortex Razor 10x50 UHD at full aperture and at 10x25mm with the aperture masks in place. In post 260 I stated my expectation that two additional stars would be visible at full aperture compared with 25mm. In fact, those two stars were seen as predicted, along with two additional stars (demonstrating the 10x50mm limiting magnitude is actually fainter than the estimated 9.5 magnitude). 

 

 

1. HD 36957 -- 8.85 magnitude

2. HD 36998 -- 8.98 magnitude

3. HD 294257 -- 9.66 magnitude

4. HD 36937 -- 9.68 magnitude

 

At 10x25mm I saw precisely what you reported -- the stars labeled 1-4 were not visible.

 

We each choose the binoculars we prefer to observe with. I respect your preference for a 10x25mm binocular and am glad you enjoy it. I prefer a 10x50 binocular because more can be seen with it, as has been demonstrated not only with the observations I have made, but also with an observation you yourself reported above (post 247).

Edited by Fiske, 12 December 2021 - 08:54 AM.

[gwlee]

Gary, Fiske's simulation simply collects two different magnitude limits and therefore a different visualization of the quantity of stars, in an equally black sky.
That simulation is completely incongruous, in general and especially with what I see in my sky. But I'm sure it's incongruent for Fiske's (and others) sky too.

As I understand the simulations, the difference in the magnitude limits reflects the 25mm differences in aperture between these two binoculars; the software driving the simulations calculates that the larger binoculars can go 1.2 magnitudes deeper, and the images attempt to show what the average person would see under otherwise ideal observing conditions using 10x25 and 10x50 binoculars. 

 

 Regardless, my question to you is how do the images in these two simulations compare to the same images in your two binoculars? 

[Fiske]

Gary, 

 

To create the Melotte 20 views I used the star magnitude control in Sky Safari, setting the magnitude limit at 8.3 for the 10x25 view and at 9.5 for the 10x 50 view. I should have set it to 9.7 for the x50 view.  (I was too conservative.)

[Grimnir]

... in testing and ranking the performance of all of my binoculars on the night sky, I find the Bishop Index comes as close as any calculation to predicting my empirical rankings 

 

I find the Adler index, mag x sqrt aperture, to be a more accurate predictor of the stellar visibility ranking of the various binoculars I have owned.

 

Graham

[ECP M42]

I believe it is possible to train yourself to make your retina more sensitive. 

Eh, let me know how to do it, because I want to get to turn off all the lights in my house before Christmas, to save a little ... you know, I have to buy new binoculars!  

 

But I don't think it's possible to change your retinal sensitivity on command. Instead, it seems to me that also you are making the same mistake as Jon, and you are confusing the possibility of recognizing celestial objects with adequate training (which is certainly possible).

 

In the preliminary of the eye exams, to evaluate the retinal sensitivity, it is necessary to calibrate the machinery for the eyes of the individual. The calibration tolerance range goes from 0 to 36dB, in scales from 2dB per step. If I am not mistaken the calculations, 36dB is equal to 4000 times the threshold light. And that means that some difference is expected between individuals' retinas. 

[ECP M42]

... this evening I observed the open cluster NGC 1981 in Orion with the Vortex Razor 10x50 UHD at full aperture and at 10x25mm with the aperture masks in place.

 

... demonstrating the 10x50mm limiting magnitude is actually fainter than the estimated 9.5 magnitude ... HD 36937 -- 9.68 magnitude

 

At 10x25mm I saw precisely what you reported ... above (post 247).

Fiske, this says two important things: 

 

1 - The stellar limit of your sky, measured on the same object, is definitely 2 magnitudes less polluted than my sky. 

2 - But despite this, yuo can't see more than what I see, with 10x25. 

 

What I did not understand, is whether with 10x25 you also see HD 36842 which is 8.13 mag or not. 

 

In #247, I reported the parity of the number of stars visible (7) in the open cluster NGC 1981, both with 10x25 and with 10x42. And the stellar limit I estimated was ~ 7.50-7.75 mag. 

 

The difference of the sky is fundamental. And there is little or nothing to discuss on this point. But now I am more sure that your home site is much better than mine, despite we mistakenly rate them as very similar (B8 and B7). And that probably (or almost certainly) your retinal sensitivity is lower than mine (seen point 2), although this does not involve anything negative, neither for you nor for me. But I guess for these reasons, you prefer to use the 10x50 from your home site, instead of 10x25.

 

Perfect!

[Fiske]

I agree there is nothing left for us to discuss here, Henry. 

Edited by Fiske, 12 December 2021 - 08:40 AM.

[gwlee]

Gary, 

 

To create the Melotte 20 views I used the star magnitude control in Sky Safari, setting the magnitude limit at 8.3 for the 10x25 view and at 9.5 for the 10x 50 view. I should have set it to 9.7 for the x50 view.  (I was too conservative.)

Fiske,

 

OK, here’s what I think you said you did, which I have written in enumerated steps that will hopefully allow anyone that’s interested to repeat your experiment:

 

1) You used your binocular mounted 10x50 with and without a 25mm objective mask to determine the dimmest star visible in Melotte 20 with and without the mask.
2) You used an astronomical chart to determine the magnitude of these stars, which were 8.3 with mask and 9.5 without.

3) You centered Melotte 20 in SkySafari, alternately set the VLM control to 8.3m and 9.5m, and captured the simulated views at both settings

4). You compared the 8.3m simulation to the masked binocular view and found they matched.

5) You compared the 9.5m simulation to the unmasked binocular view and found they matched.

 

Did I get it right? If so, I want repeat your experiment here when weather permits using my 8x32 and 10x50,  and perhaps Henry will want to repeat it at his site using his 10x25 and 10x50.

 

Being at a darker site here, I expect the VLM for both of my binoculars to be different than yours, but expect the difference between the views to be similar to what we see in your post #260. 

 

Gary

[gwlee]

I find the Adler index, mag x sqrt aperture, to be a more accurate predictor of the stellar visibility ranking of the various binoculars I have owned.

 

Graham

Graham,

 

I don’t disagree with you, but the output of both the Adler Index and the Bishop Index is a unit less number.  BI example: the BI for for my 8x32 is 256 and the BI for my 10x50 is 500. (Ratio 500/256 or 195%). AI example: AI for my 8x32 is 45.2 and AI for my 10x50 is 70.7 (Ratio ~71/45 or 158%).

 

Both models clearly rank the 10x50 superior for viewing stellar objects in the night sky, and my empirical testing shows the 10x50 to be significantly superior, but I can’t put an objective number on its superiority, so I have no empirical basis for saying the either the AI or BI provides a more accurate figure of merit. What leads you to believe the AI is a more accurate predictor? 

 

Thinking about this question a bit more, I think the small percentage difference between these two models could be converted to magnitude, and a person could observe stars of known magnitude to form a somewhat objective about which is more accurate.

 

I think it would take the observational skills of a very experienced variable star observer though. For example, the AI comparison between the 8x32 and 10x25 is 45 vs 50, and the BI comparison for these two binoculars is 256 vs 250. The predictions are essentially the same, so very difficult for a human observer to make an empirical determination of which is model is most accurate. 
 

Gary

Edited by gwlee, 12 December 2021 - 04:18 PM.

[Fiske]

Gary, that is essentially what I did, though I did not compare the charts directly with the view in the binocular. My rough estimate at the binocular was that 25% more stars could be seen at 50mm compared with 25mm. The charts approximate that effectively. Comparing the charts with actual views (I would use inverse charts with black stars on a white background) may well demonstrate that I under-estimated the additional stars visible at full aperture.

 

Henry is not comparing 10x25 versus 10x50. He is making the comparison between a Leica 10x25 Ultravid and a 10x50 binocular, of undeclared make, which he has reduced in aperture to 42mm by painting the objectives.  Presumably he used black paint for its lower albedo.  This falls short of the aperture mask approach, needless to say, because it introduces quality variation between the instruments. Somewhat amusingly (from my perspective) the cluster he chose effectively demonstrates not only the advantage of 10x50 versus a 10x25 binocular, it further demonstrates the advantage of 10x50 over a 10x42 instrument because the fainter stars seen in NGC 1981 fall just below what I have found to be the limiting magnitude of 10x42 binoculars from typically light polluted skies. I will follow up with an observation of NGC 1981 with my superb Nikon 10x42 HG. Oh, and also with the Canon 10x42L IS. 

 

Here is an interesting point about an instrument's limiting stellar magnitude in light polluted versus darker skies. The variation is considerably less than one might anticipate because stars are less affected by light pollution than are extend objects like nebula. Furthermore, increasing aperture increases the brightness of stars (because they are point sources) while increasing magnification does not decrease their brightness, so where contrast between the night sky and extended objects cannot be increased, the contrast between stars and the night sky can be increased dramatically. I will have more to say about this in a subsequent post, but last night I also made observations of NGC 1981 using the 100XL-SD with 7mm eyepieces (80x) and observed stars down to about 12.68 magnitude or a bit fainter. That is surprisingly faint given an 8 day moon and my neighbor's insanely bright Christmas lights.  I would expect to see fainter stars at a darker site, but would be surprised to find the increase is more than one magnitude (which is still a tremendous increase in the number of stars seen -- the number increases geometrically at fainter magnitudes because there are many more faint than bright stars in the sky).

 

I look forward to your report based on actual observations. Thank you! 

Edited by Fiske, 12 December 2021 - 03:44 PM.

[gwlee]

Gary, that is essentially what I did, though I did not compare the charts directly with the view in the binocular. My rough estimate at the binocular was that 25% more stars could be seen at 50mm compared with 25mm. The charts approximate that effectively. Comparing the charts with actual views (I would use inverse charts with black stars on a white background) may well demonstrate that I under-estimated the additional stars visible at full aperture.

….

 

I look forward to your report based on actual observations. Thank you! 

For convenience, I am going to use my 8x32 instead of a 10x25 because I have one. As I explained in a previous post (#286), both the Adler and Bishop models predict their performance is essential identical.

 

The eminent arrival of another atmospheric river that will be snow at my altitude will give me the time to jury rig a binocular mount for my 8x32 roof, and I have two tripods, so I can do my comparisons side-by-side in hip deep snow when the storm ends. 

Edited by gwlee, 12 December 2021 - 04:33 PM.

[gwlee]

In the preliminary of the eye exams, to evaluate the retinal sensitivity, it is necessary to calibrate the machinery for the eyes of the individual. The calibration tolerance range goes from 0 to 36dB, in scales from 2dB per step. If I am not mistaken the calculations, 36dB is equal to 4000 times the threshold light. And that means that some difference is expected between individuals' retinas. 

Henry,

 

You seem to be more knowledgeable than most about retinal sensitivity. Do you happen to have any authoritative graphs that you can share that will show us the distribution of this factor in the general population? 
 

Gary

[Fiske]

For convenience, I am going to use my 8x32 instead of a 10x25 because I have one. As I explained in a previous post (#286), both the Adler and Bishop models predict their performance is essential identical.

 

The eminent arrival of another atmospheric river that will be snow at my altitude will give me the time to jury rig a binocular mount for my 8x32 roof, and I have two tripods, so I can do my comparisons side-by-side in hip deep snow when the storm ends. 

I'm sure that will be fine, Gary. 

 

I also have a quite nice 8x32 -- a Nikon LX Premier. So perhaps will do a bit of junior league playoffs. 

[KennyJ]

As regards the Bishop v Adler v A.N.Other formulae, some of the longer standing members here may recall former forum moderator Ed Zarenski carrying out extensive research on the topic, using actual recorded, detailed night sky observing notes to back up his modifications, resulting in his own personal variation, entitled Binocular Performance Index.

 

All of this can easily be found under the "Best Of" section pinned to the top of this forum.

 

I would have provided an instant link but for some reason certain aspects of my PC and those of this web site prevent me from doing so.

 

Kenny

[Rich V.]

Here you go, Kenny, I think this is the original EdZ document. 

 

https://www.cloudyni...performance.pdf

 

Rich

[ECP M42]

What leads you to believe the AI is a more accurate predictor? 

Gary, I'm not answering for Graham, but I try to bring my own thoughts to the matter.

 

The Adler index treats both binocular values (M and A) with the same "meter", as far as exit pupil light is concerned in proportion with the magnification. And this leads me to assume that, using the square root for the aperture, there is a coherent balance between the two functions. 

 

Instead, the Bishop's index directly uses the diameter of the lens, which obviously produces a disproportionate value overall, providing a binocular value shifted towards the light.
So, in my opinion this index (which is the simplest of all) could provide a more suitable evaluation for the observation of faint extended objects in the unpolluted night sky. 

 

But that's just my logical interpretation. 

 

 

Do you happen to have any authoritative graphs...? 

I don't have any charts to show, but you should find info on the subject in this article:

 

"The dynamic range of the luminance of the differential stimulus is between 0.08 and 317.04 cd/m^2, corresponding to 36-0 dB of PS."

 

 

 

Henry is not comparing 10x25 versus 10x50. He is making the comparison between a Leica 10x25 Ultravid and a 10x50 binocular, of undeclared make, which he has reduced in aperture to 42mm by painting the objectives. 

Eh Fiske, I'd like to, but I don't have a Leica Ultravid 10x25  

I only have a simple medium quality binoculars (Opticron DBA Oasis), with the same FOV as the Porro 10x50 reduced to 10x42 and with about the same transmittance (+/- 1%). But as I have already explained, the vision quality of the modern Porro 10x50 (class 100 €) is slightly better than that of my 10x25 roof. So, the "difference" that I see between the two binoculars is substantially given by the whole of my heavily polluted sky and by the high retinal sensitivity.
But if you want, I could use the 10x50 (42) with the 25mm masks, in the next tests. 

 

 

Here is an interesting point about an instrument's limiting stellar magnitude in light polluted versus darker skies. The variation is considerably less than one might anticipate because stars are less affected by light pollution than are extend objects like nebula. 

This point is not so clear to me. I think it's obvious to everyone that the "limiting stellar magnitude" is purposely referring to stars only and not nebulae. Or maybe not?  

Stellar = Relative to the stars. 

 

 

Furthermore, increasing aperture increases the brightness of stars (because they are point sources) while increasing magnification does not decrease their brightness, so where contrast between the night sky and extended objects cannot be increased, the contrast between stars and the night sky can be increased dramatically. 

Fiske, here too in my opinion there is a bit of confusion.

Increasing the exit pupil increases the brightness throughout the image, thus also the brightness of the nebulae.
Increasing the magnification without increasing the aperture produces a narrower exit pupil, which reduces the brightness over the entire image, including the stars.

The contrast between the objects and the background sky is an apparent contrast, not a real one: it is an effect of perception, which is visible under certain conditions. 

 

 

PS: Just to understand, but with the 10x25 have you also seen HD 36842? 

Edited by ECP M42, 12 December 2021 - 10:35 PM.

[Fiske]

Eh Fiske, I'd like to, but I don't have a Leica Ultravid 10x25  

I only have a simple medium quality binoculars (Opticron DBA Oasis), with the same FOV as the Porro 10x50 reduced to 10x42 and with about the same transmittance (+/- 1%). But as I have already explained, the vision quality of the modern Porro 10x50 (class 100 €) is slightly better than that of my 10x25 roof. So, the "difference" that I see between the two binoculars is substantially given by the whole of my heavily polluted sky and by the high retinal sensitivity.
But if you want, I could use the 10x50 (42) with the 25mm masks, in the next tests. 

 

 

This point is not so clear to me. I think it's obvious to everyone that the "limiting stellar magnitude" is purposely referring to stars only and not nebulae. Or maybe not?  

Stellar = Relative to the stars. 

 

 

Fiske, here too in my opinion there is a bit of confusion.

Increasing the exit pupil increases the brightness throughout the image, thus also the brightness of the nebulae.
Increasing the magnification without increasing the aperture produces a narrower exit pupil, which reduces the brightness over the entire image, including the stars.

The contrast between the objects and the background sky is an apparent contrast, not a real one: it is an effect of perception, which is visible under certain conditions. 

 

 

PS: Just to understand, but with the 10x25 have you also seen HD 36842? 

Henry,

 

I somehow thought you owned a 10x25 Ultravid.  Perhaps one will come your way someday.

 

By "limiting stellar magnitude" I meant stars -- the faintest star visible.

 

Increasing magnification without increasing aperture reduces the brightness of extended objects like galaxies and nebula because they are enlarged so the light is spread over a larger area. But since stars are point sources, and cannot be enlarged, increasing magnification does not reduce the brightness of stars. All the light is still concentrated in a single point. At the same time, increasing magnification decreases the brightness of the sky, which is actually an extended object. This is how the contrast between stars and the background sky is increased. In the case of extended objects, the contrast cannot be increased because the object, like the sky, is being enlarged through magnification. As a consequence very few galaxies can be seen in light polluted skies even with large telescopes -- the sky is brighter than the galaxy and remains brighter even when magnified (enlarged) -- the brightness ratio between the galaxy and the sky does not change. Dark skies are far more critical for observing dim extended objects like galaxies than for observing stars.

 

Why do you think I spend so much time fooling around with double stars from my suburban yard? 

 

And yes, I can see HD 36842 with the Razor masked to 25mm (10x25).

Edited by Fiske, 13 December 2021 - 12:53 AM.

[Rich V.]

Fiske, here too in my opinion there is a bit of confusion.

Increasing the exit pupil increases the brightness throughout the image, thus also the brightness of the nebulae.
Increasing the magnification without increasing the aperture produces a narrower exit pupil, which reduces the brightness over the entire image, including the stars.

The contrast between the objects and the background sky is an apparent contrast, not a real one: it is an effect of perception, which is visible under certain conditions.

I think rather than using the term "apparent contrast" we should be talking about contrast ratio which is real and measurable.  

 

Decreasing or increasing the exit pupil at a given aperture will not change the contrast ratio; object and sky background will dim or brighten but the ratio between them remains unchanged. 

 

Stars are point sources, not extended objects.  Aperture alone dictates their brightness, not exit pupil size.

 

I posted this 2004 discussion with Bill Ferris about contrast ratio earlier but I think it deserves attention again, apparently.

 

An Explanation of Contrast Ratio by Bill Ferris

 

Over and out...

[Fiske]

I re-observed NGC 1981 last night (Sunday 12 December 2021) with additional binoculars. Letters have been added to the chart indicating four brighter stars, all of which are readily seen at 10x25 (and all of the other instruments except the 8x32 binocular). Comments about the view in individual binoculars are included below.

 

 

A. HD 36936 -- 7.57 magnitude

B. HD 36883 -- 7.74 magnitude

C. HD 36865 -- 7.48 magnitude
D. HD 36842 -- 8.13 magnitude

1. HD 36957 -- 8.85 magnitude

2. HD 36998 -- 8.98 magnitude

3. HD 294257 -- 9.66 magnitude

4. HD 36937 -- 9.68 magnitude

 

Nikon 8x32 LX Premier

ABCD are not as easy to see with the 8x32 compared with the 10x25. They still can be seen but it is more effort, particularly D (HD 36842) which is difficult to hold steadily in view. The 8x32 was on a monopod, not a tripod, which may have been a slight factor, though the view was reasonably steady and in my opinion is not sufficient explanation for the difference. The most likely explanation is the lowered contrast between the stars and the background sky because of the reduced magnification, which is consistent with the APM 12x50 result below.

 

10x25 (Razor 10x50 UHD masked to 25mm aperture)

Consistent with previous observations -- stars A-D readily seen / stars 1-4 not seen.

 

Nikon 10x42 Monarch HG

1. Seen in averted about 60% of the time.

2. Seen in averted about 25% of the time.

3-4. Not seen.

 

Canon 10x42L IS

1. Seen in averted about 25% of the time.

2-4. Not seen.

Consistent with the Nikon 10x42 being brighter than the Canon 10x42L.

 

Razor 10x50 UHD

1-2. As on previous night, steadily in view.

3. Seen about 50% of the time.

4. Seen about 75% of the time.

Stars 3-4 were not as easily seen as on the previous night, possibly because I observed the cluster earlier last night and Orion was not at its maximum altitude.

 

Fujinon 10x50 FMTR-SX

1-2. Steadily in view

3-4. Both somewhat more difficult to see compared with the Vortex. Both could be glimpsed occasionally.

 

APM 12x50 ED MS

1-4. All stars steadily in view, though 3 is more challenging to see than the other stars, likely due to its proximity with star A.

The Razor and the APM are both 50mm binoculars and both excellent optically. Additional magnification is the clear explanation as to why stars 3-4 are more readily seen in the APM, presumably the result of background sky darkening?

 

Resolux 10.5x70

1-2. Seen steadily but not as easily seen compared with the Razor 10x50.

3-4. Occasionally glimpsed.

I suspect two factors account for the weaker performance from the larger aperture binocular. Pupil dilation to begin with, suggesting that the effective aperture of the Resolux was closer to x50 than x70 because my pupils were not dilated much beyond 5mm. Secondly, since I have begun observing constantly with glasses, the Resolux eye cups do not work as well for me as they did previously without glasses. Extended they are significantly too long and folded down they are too short (beaning). The result is that correct eye position is quite difficult to maintain, which has a significant impact on observing fainter stars. A set of replacement eyecups (OB 15x70 Ultra eyecups) is on the way from Oberwerk. These are shorter than the Resolux eyecups and will hopefully match my eye relief requirements when wearing glasses.

 

Oberwerk 15x70 Ultra

1-4. All stars readily seen in direct vision.

The combination of additional magnification and aperture makes a noticeable difference in the visibility of stars 1-4.

 

Of all these instruments, the 15x70 Ultra shows the fainter stars most readily, followed by the 12x50 with the Razor 10x50 just behind that. I would say that the magnitudes of stars 1-4 are enough above the limit for the 12x50 that the difference between it and the 15x70 does not significantly affect the visibility of the stars in question.They are slightly brighter at 15x70. Were slightly fainter stars visible in the cluster, say around 10.0 magnitude, I would anticipate them being more readily seen with the 15x70 Ultra than with the APM 12x50.

 

While observing NGC 1981, a quite bright meteor streaked through the lower portion of the FOV -- a Geminid. Quite fun.  Later when I was having a quick peek at SHJ 49 Orion, an excellent 10x50 binocular double star, an even brighter Geminid streaked across the field, actually leaving an after image.

 

Thank you for reading. 

Edited by Fiske, 13 December 2021 - 09:09 AM.

[f18dad]

Awesome work!

 

All theories, no matter how mathematically compelling or otherwise, need to be tested. Edison understood this. Einstein did not believe "spooky action at a distance", but testing has proven it to be fact.

Edited by f18dad, 13 December 2021 - 10:23 AM.

[Grimnir]

Superb report Fiske!

 

Graham

[Fiske]

Thanks guys.  It is nice to be appreciated. 

 

Making comparison observations of a specific object like this is the best way to understand the performance characteristics of different binoculars and how well they match your own preferences. I also plan to repeat these observations from a darker location to see how that affects the results. From my point of view, optical theory is more useful to account for observational results than to make purchase decisions before getting one's hands on whatever binocular.

 

My biggest take away from the exercise is I could keep the Vortex 10x50 and the Maven 10x56, dispense with the rest of the 10x binoculars, and be perfectly content. I go back and forth about the Canon, but the optical performance advantage of the Vortex and Maven is important to me, and I much prefer mounted binoculars to hand held observing, so Canon's stabilization feature isn't important to me when all is said and done. It will be interesting to see how the Maven 12x56 matches up to the APM 12x50. Premium quality roof prisms in this range cost considerably more than the equivalent porros (like the APMs and the Fujinon FMT) but overall they are slightly better optically and considerably more comfortable to use due to the advantage of twist up versus fold up eyecups. I may experiment with eyecup options for the porros -- either finding suitable replacements or learning how to create them with 3D printing -- or I might just say bother it and spend my time observing with the Vortex and Maven(s) instead. 

 

We will see...

 

Fiske

Edited by Fiske, 13 December 2021 - 01:12 PM.

[Masonry00]

Awesome work!

 

All theories, no matter how mathematically compelling or otherwise, need to be tested. Edison understood this. Einstein did not believe "spooky action at a distance", but testing has proven it to be fact.

Einstein, who rarely set foot in a scientific laboratory, might not be the best example here. He once wrote:

 

"But we have higher mathematics, haven't we? This gives me freedom from my senses. The language of mathematics is even more inborn and universal than the language of music; a mathematical formula is crystal clear and independent of all sense organs. I therefore built a mathematical laboratory, set myself in it as if I were sitting in a car, and moved along with a beam of light."