1978 replies to this topic

[Fiske]

Fiske, I'm afraid you are taking too many "simplistic" (or simplified) theories for granted, which you have never personally tested (or not properly).

The levels of brightness and contrast we talk about most often are those of our visual perception. Which, in addition to having notable variations between individual and individual, are not absolutely linear with the levels of photometry and even less with those of electromagnetic-quantum physics. The difference in light of the exit pupil is a linear measure to the photometry or rather, to the physics of light.

You talk about things "already been discussed", as if this could give more truthfulness and value to what you say above (even if it were wrong).
So I ask myself: but by whom have they already been discussed and how? And above all for what purpose?

 

What I have reported is what I have seen yesterday night (which is more or less what I see every time and that I have already reported before). Still, it sounds like you want "to spin the omelette", saying that in any case a 10x50 provides brighter stars than a 10x25.
Maybe you should reread my report better! But, anyway ...

Henry,

 

You're just not that familiar with the night sky. You make a superficial view of a star field, not understanding what could be observable if you only knew what you were looking at, and since you don't know what you are missing, the difference between a 10x25 and a 10x50 binocular doesn't seem significant to you. That you don't see the stars as brighter in the larger glass is intriguing, because it is immediately apparent to me. Also what you claim to see goes against basic principles of optics. 

 

I am guessing you rarely, if ever, look at deep sky objects because you don't know how to find them. Earlier this year when I suggested you could learn how to star hop, and get an app like SkySafari or a basic atlas so that you could observe DSOs, your response was essentially "why bother"? Are you capable of locating any of the objects or star fields I recommended above?

 

That you are pleased with your 10x25 binocular is a great thing. A 10x50 won't fit in your pocket, I'll give you that. 

 

Fiske

Edited by Fiske, 28 November 2021 - 09:55 AM.

[Fiske]

And why assume I might have sufficient binoculars on hand to do side by side comparisons between smaller and larger instruments? 

 

[ECP M42]

Surely, not knowing the sky like you, it is more difficult for me to do certain tests, but I can easily understand if in an area I see 5 or 6 stars (for example).
I bought SkySafari, but I prefer Stellarium, because it seems more technical to me. In this case (last night's test) I didn't look for what I saw, it was just a test outside the window, lasting a maximum of half an hour. I repeat, in these conditions of polluted sky, I have no interest in observing the stars with commitment and if anything, not with a 10x.
I'll try the 10x50 with the 10x25 again, in site B4 when I go, on a clear day. I'm pretty sure the difference could be bigger. And of course, I'd also love to try a good 10x70 on a dark B1-2 site, but I don't know when or if it will happen. 

 

That you don't see the stars as brighter in the larger glass is intriguing, because it is immediately apparent to me.

Also what you claim to see goes against basic principles of optics.

Here it's not clear to me what you mean. Obviously, the brightest stars are also seen in the largest binoculars (10x50).
And the basics of optics, simply, can't describe what we see. Not even photometry can do that. Apparent contrast effects, belong to a much more complex and wide scientific field than simple basic optics. 

 

Henry

[gwlee]

Time spent behind the keyboard seldom leads to the same understanding of observing as time spent behind the eyepiece.

Attached Thumbnails

• 

Edited by gwlee, 28 November 2021 - 12:29 PM.

[Erik Bakker]

Well said.

 

Astronomical instruments, including binoculars, are better suited to visual astronomers than armchair astronomers. The internet made that clear. For the evaluation of instruments, time under the stars and experience make a big difference.  Comparing instruments side by side is a big help too IME. 

[BUDSBOY]

Well said.

 

Astronomical instruments, including binoculars, are better suited to visual astronomers than armchair astronomers. The internet made that clear. For the evaluation of instruments, time under the stars and experience make a big difference.  Comparing instruments side by side is a big help too IME.

Time spent in front of this screen has convinced me that I need to add 10x50 binoculars to my collection.

Kind of a hybrid thing going on here. 

[jprideaux]

At least we all agree that we like using binoculars (and talking about using binoculars   ).

 

As for team 10x,  I was just today comparing my non-alpha (cheap) Nikon 10x50 (6 degree) lookout 2 with my Canon 10x42 IS and between just these two, there is really no comparison.  The Canon easily wins for me.  The only advantage of the Nikon is that it is much lighter.  Of course my Nikon was one of Nikon's earlier inexpensive models marketed for those that did not want to spend a lot so it isn't one of the better examples of 10x50 that people tend to recommend here.  It was just a pair that I had laying around for years.  

[richsvt]

I was out last night with a new Oberwerk Deluxe 10x50. Had some very nice views of the Double Cluster. Not as bright as the Ultras, but sill decent. Cloudy tonight with a hint of snow, shame.

[Fiske]

I came across WZ Cassiopeia near Caph last night with the 100XL-SD and 20mm XW eyepieces (28x), which is the primary component of double star STTA 254. It was gorgeous -- blood orange primary with a brilliant sapphire companion. In a rich field but so eye catching I stopped observing to identify it before continuing. Also a carbon star.  Here is an AAVSO chart for estimating magnitude. It's on the brighter end of its range at present, current observations put it around 7th magnitude. Near minimum it will actually be fainter than the secondary.

 

STTA 254 / WZ Cassiopeia
00h01m +60*21'
7.40/8.33 57.8" pa 89*
Spectral type C9,2JLi. Magnitude varies from 6.3 to 8.8 over 373 days.

 

 And here is a chart made with SkySafari -- the FOV ring is 6.5 degrees.

 

 

It is also a fine double viewed with the APM 16x70, the colors less intense but still readily seen. But would it be visible with 10x binoculars?

 

I observed it with the following -- Canon 10x42L, Nikon 10x42 Monarch HG, Maven b.5 10x56, Vortex Razor 10x50 UHD, and Vortex Viper 10x50. All instruments mounted except the Canon. The deep red primary is striking in all these instruments, and the secondary readily seen in all. The color of the secondary is subtle in these binoculars compared with the larger instruments. Best seen with the Razor UHD, followed by the Maven. In somewhat predictable descending order the Viper, Nikon HG, and last the Canon, in which the secondary can be seen but looks grayish white.

 

However, when I was reviewing star charts later, after putting the binoculars away for the night -- Sky Atlas 2000, Uranometria 2000, and Sky Safari -- I realized the V asterism indicated in the chart with green lines could not be seen on either of the printed charts and was somewhat hard to pick out even with Sky Safari. It was obvious and striking with the 10x binoculars. What did I do? Grabbed the Canon and stepped back outside for a quick refresher on the star field. For quick peeks, nothing competes with it.

 

Fiske

Edited by Fiske, 28 November 2021 - 10:55 PM.

[PKDfan]

Hi Fiske!
I am not sure(again) if this is off topic but since someone is off on a strange tangent about exit pupil and aperture and how sky darkness and magnification work I thought a comparison between changing exit pupil while holding aperture constant would be apropo.

My new 7-15x×35 Tasco 101Z 'Zip'.
The exit pupil(ep) ranges from 5mm to 2.3mm.

It is important to understand that solely reducing ep is a gradual improvement in the quality of the view, is why during daytime views the quality of image is best at 10x or 11x.(edit at 35mm) The view seems more true to life as the eye is working at 3mm, is using the best corrected area of the eye.

That is the first effect. Reduced exit pupil affects eye quality and improves it, the improvement begins at 4mm and is really noticed at ~3mm.

My light pollution is at B9 levels so at first note the view at 5mm and 7x is very washed out and star count is at the lowest number, as you gradually improve image scale by adding more power to say 12x or 13x more and more stars begin to show through,(edit about 3mm ep and below) the perceived sky darkness rapidly grows and is seen as very dark and finally at 15x the most stars are seen in the darkest sky and that could be a very high # if you happen to be at a great spot but thats hard to tell at 7x and only seeing maybe one star in the washed out bright sky.

Now with this thought lets add to the mix 15×70s. Double the aperture collects 4 times the light and the view in comparison to the 35mm pair is 4 times brighter but the exit pupil is not at 2.3mm anymore its 4.7mm!
So sky brightness zooms back up to intolerable levels again and to be equivalent as before they would need to be 30×70.(edit double the power reduce brightness by a fourth thus equaling the 15×35.)

So it can be difficult to reconcile the various factors as to what exactly will be visible in a given pair of bins.

Generally,

Add more power to a given aperture is an increase in stars.

Add aperture brightens everything in view includes star brightness and background sky.

Add aperture adds more stars but sky conditions can make this number vary wildly.

Adding both aperture and power nets the highest increase in star count.

In this post I say that the bigger pair will show more but whats explicit is that background LP will also be more!

To achieve a similiar gain the 15×70s need to be at much darker skies or they need to be 30×70.

Clear as mud?

This is why DARK skies are so wonderful, the background white noise is reduced, possibly to zero, thus giving highest contrast possible.


Cs&Gs
Edit structure, typos

Edited by PKDfan, 29 November 2021 - 05:06 AM.

[Erik Bakker]

Well said PKDfan 

[Erik Bakker]

And one thing has become very evident over the past decades for me: dark skies make a HUGE difference in performance with astronomical instruments, especially so when exit pupils get in the 5-7mm territory.

 

The bigger the exit pupil, the more pronounced the improvement in celestial views under truly dark skies vs brighter, let alone very bright city skies. 

[ECP M42]

The Internet has also taught us that: it is precisely those who lack the skills to answer on the merits, who often convert their "hatred" towards the (competent) person. 

 

So please don't shoot the "keyboard and armchair astronomer". What I saw is very simple: the 6 stars I saw with 10x50 in that area of ​​the sky, I also saw with 10x25 binoculars. No more or less stars. 

 

What level of astronomical experience is required to be able to count to 6? 

 

 

Fiske, brightness and luminance are two different things. You have to decide what value you are referring to. Because, any star in any binocular will never have, more luminance than what you see with the naked eye, if anything less. Brightness (understood as individual perception) is a subjective value that depends a lot both on the eyes, on the perception and on the apparent contrast between object and background.
Contrast is the ratio between two luminosities, and in this case, being an apparent contrast, it is by no means linear with the received light energy (or luminance).
Claiming that a 10x50 in any case makes you see the brightest stars and therefore "it is mandatory" that you have to see more stars (in number) than a 10x25, otherwise you are out of the basics of optics, ... it's nonsense incongruent. 

 

Can you understand what I'm trying to explain to you? 

 

Henry

Edited by ECP M42, 29 November 2021 - 07:52 AM.

[Fiske]

Hi, PKD. Thanks for your post.

 

Skies from my suburban yard are in the Bortle 7 range, and whether that is the difference compared with your preferences or something else, I have a strong liking for 5mm exit pupils. So, for example, I much prefer a good quality 10x50 view to a 10x42. The views don't seem washed out to me -- stars just seem brighter, more vivid and colorful, and the view more engaging. I don't find a significant improvement with a 10x70 from my yard with regard to brightness, but that is likely because my pupils aren't dilated enough to make the effective aperture of the binocular much larger than the 10x50. I need to do some more comparisons and evaluation of that. Without doubt, 7x50s are more engaging from a darker location. I don't use them much from my yard, other than for occasional comparisons. Actually, since I still prefer 10x50s to 10x42s even from darker locations, I guess it probably isn't a consequence of the sky background.

 

My preferred wider field "finder" binocular when observing from my yard is a Nikon 8x42 Monarch HG, which is the binocular I use almost constantly for daytime viewing. It has an 8.3 degree field of view. I have fun with some of the smaller instruments -- Kowa 6.5x32, 6x30, and Nikon 8x32 LX Premier and 7x35 AE, but the can't really keep up when it comes to observable details. The Kowa 6.5x32 is nice because it provides such a large FOV, 10 degrees, effective for scanning large areas of the sky.

 

I can't really say I am more pleased with an instrument like the APM 16x70 from a dark location compared with my yard, which is not to say that the views aren't spectacular from a dark site (they certainly are), but I am delighted with the instrument (and the OB 15x70 Ultra) from my yard as well. I guess my expectations are tempered by the reality of light pollution. I am constantly pleased and appreciative of what can be seen despite the light pollution. If I were determined to observe galaxies, for example, it would be a frustrating experience for sure. OTOH, my attitude is what can I really see here -- double stars, carbon stars, open clusters, variable stars, asterisms, brighter DSOs, etc. It's kind of like going to a thrift store and just seeing what's available, versus looking for some specific thing, which you are unlikely to find and be disappointed about.

 

I spent much of my evening last Friday delving around in Camelopardalis, and made a serious effort to see the galaxy NGC 2403. In this effort I was using 10x50 binoculars for orientation, and the 82XL+14mm eyepieces (32x) to observe the galaxy. I "might" have seen a faint haze at the correct location, but nothing definite enough to call a confirmed observation. Still, just navigating to it, and knowing exactly where it should be seen was fun for me. Maybe that is odd?  But then I noticed a brighter star nearby, which I could actually see naked eye -- which could not possibly be anything in Camelopardalis.  And I realized it was Muscida -- 1/Omicron Ursa Majoris. I was so pleased with that. Nothing of the recognizable Ursa Major asterism (the Big Dipper) was visible due to trees and buildings obscuring it. It's rising in the east at this time of the year. And Muscida isn't part of the asterism anyway. It's well away from the dipper. I'm not sure I would be able to readily identify it when the dipper is well overhead. I don't recall any other occasion where I have recognized it apart from the constellation as a whole. Honestly, that was as pleasing to me as seeing NGC 2403 from my yard would have been.

 

Fiske

[Fiske]

What level of astronomical experience is required to be able to count to 6? 

 

Because, any star in any binocular will never have, more luminance than what you see with the naked eye, if anything less. 

What 6 stars were they, Henry? And what was their magnitude? And what other stars might have been seen in the field of view with more versus less aperture? Randomly pointing your binocular at the sky, particularly a light polluted sky (and observing through a window?), doesn't provide much useful information. 

 

About star brightness, you are mistaken, as has been explained to you by multiple participants here. Because they are point sources, not extended objects, star brightness does increase as aperture increases. So yes, stars are considerably brighter seen through a binocular than with the naked eye. You seem to be confusing stars with things like galaxies, which are extended objects not point sources and cannot be brighter than the naked eye view, though they can be considerably larger. I will remain forever grateful to Rich V for helping me understand the distinction. 

 

Fiske

Edited by Fiske, 29 November 2021 - 09:41 AM.

[Jon Isaacs]

At least we all agree that we like using binoculars (and talking about using binoculars   ).

 

As for team 10x,  I was just today comparing my non-alpha (cheap) Nikon 10x50 (6 degree) lookout 2 with my Canon 10x42 IS and between just these two, there is really no comparison.  The Canon easily wins for me.  The only advantage of the Nikon is that it is much lighter.  Of course my Nikon was one of Nikon's earlier inexpensive models marketed for those that did not want to spend a lot so it isn't one of the better examples of 10x50 that people tend to recommend here.  It was just a pair that I had laying around for years.  

 

One thing to keep in mind: Inexpensive binoculars very often do not operate at full aperture. I had a pair of Lookout 2's and I don't remember the exact numbers but they were not operating at full aperture. Many budget 10x50s are only operating at around 40mm. And then there's the coatings.

 

If one wants to understand the effect of aperture on brightness and contrast, the best way is with aperture masks, use one pair of binos and reduce the aperture by partially covering tje objectives. This removes the optical quality of the binoculars from the equation though they need to be operating at full aperture and the observer's eyes need to be fully dilated. 

 

I think dark skies are best for such comparisons but under light polluted skies, open clusters are ideal because they provide a repeatable group of stars, look at M35 and see how many stars you see.

 

Jon

[Fiske]

Thanks for this, Jon.

 

I have been thinking about doing the aperture mask experiment with one of my 10x50s and the project is getting higher on my priority list. 

 

Fiske

[Corcaroli78]

Time spent behind the keyboard seldom leads to the same understanding of observing as time spent behind the eyepiece.

Hi gwlee:

 

Quick off-topic:

 

Which tripod do you have in the picture? with the crank column seems a good option for small RFT´s and binos.

 

Thanks for the hint

Carlos

[tmichaelbanks]

As Mr. Bakker so aptly puts it:

 

"And one thing has become very evident over the past decades for me: dark skies make a HUGE difference in performance with astronomical instruments, especially so when exit pupils get in the 5-7mm territory."

 

On vacation this past summer, at the shore looking southeast away from the land-based light pollution, skies were very dark and I was able to view objects with my Fuji 10x50 that I typically needed my XT8 to view well from my light-polluted suburban back yard.  Much of our equipment machinations would be moot under truly dark skies.  Sigh....

[gwlee]

Hi gwlee:

Quick off-topic:

Which tripod do you have in the picture? with the crank column seems a good option for small RFT´s and binos.

Thanks for the hint
Carlos

[gwlee]

Manfrotto 475B

[f18dad]

Hi gwlee:

 

Quick off-topic:

 

Which tripod do you have in the picture? with the crank column seems a good option for small RFT´s and binos.

 

Thanks for the hint

Carlos

 

Depending on your use the 475B at 74" maximum height extension could be a little short for observing 90 degree zenith while standing. Most recommend 6" taller than your height for this function. The 3036 (058B) and 028B are over 80" maximum height extension and accommodate this requirement. At 44 lbs the 475B has a nice load capacity.

[gwlee]

Depending on your use the 475B at 74" maximum height extension could be a little short for observing 90 degree zenith while standing. Most recommend 6" taller than your height for this function. The 3036 (058B) and 028B are over 80" maximum height extension and accommodate this requirement. At 44 lbs the 475B has a nice load capacity.

I mostly use the 475B with a 72mm f6 refractor. It works well with this scope, and I am sure it could a bit larger scope, but I think it’s specified 44# load is unrealistically optimistic for astronomy. It seemed OK for low power viewing when loaded with the 16# load of my 92mm f6.7 refractor and SV M2C mount, but haven’t extensively tested this configuration. I assume it would handle a binocular of equivalent weight. 
 

To me, it works well  for astronomy with my 10x50 FMT-SX and FarPoint binocular mount, but I am only about 5’10” and seldom use a mounted binocular for astronomy. However, I often mount the 10x50 for terrestrial viewing with the 475B. 

Edited by gwlee, 30 November 2021 - 01:51 PM.

[gwlee]

The Internet has also taught us that: it is precisely those who lack the skills to answer on the merits, who often convert their "hatred" towards the (competent) person.

 

Henry,

 

I am not a competent person, but I have noticed that CN members who consistently demonstrate their technical competence tend to become highly regarded here overtime. 
 

Gary

[Rich V.]

I mostly use the 475B with a 72mm f6 refractor. It works well with this scope, and I am sure it could a bit larger scope, but I think it’s specified 44# load is unrealistically optimistic for astronomy. It seemed OK for low power viewing when loaded with the 16# load of my 92mm f6.7 refractor and SV M2C mount, but haven’t extensively tested this configuration. I assume it would handle a binocular of equivalent weight. 
 

To me, it works well  for astronomy with my 10x50 FMT-SX and FarPoint binocular mount, but I am only about 5’10” and seldom use a mounted binocular for astronomy. However, I often mount the 10x50 for terrestrial viewing with the 475B. 

FWIW, the 475 is a 26# rated tripod like the 028, 058 and the now discontinued 3036.  The 475 is 10" shorter than than the similar 3036 and 058 and about 15" shorter than the 028.  The 117B is the 44# rated version of these tripods using the same crown assy but with shorter steel legs.

 

I have a 475 I use with a small refractor but prefer my 3036 tripods for binocular use because the 475 is a bit too short for my standing use.

 

Rich