AFOV vs Aperture Poll

(Tony Flanders) wrote in message m...

But for star clusters, and particularly globular clusters, the 12-inch
scope under heavy light pollution would have a *huge* advantage.

Oh yes, then there's planetary nebulae too. I can think of two planetary
nebulae that are interesting in 10x50 binoculars, namely the Helix and M27.
Maybe M97. The rest are visible as stars or slightly fuzzy stars, if at all.

In a 12-inch scope, however, there are dozens of planetary nebulae bright
enough to show lots of structure even under very heavy light pollution.

- Tony Flanders

Jon Isaacs wrote:

snip
I have gotten used to the wider fields of view so viewing through a Plossl
seems like looking down a drain pipe.
unsnip


I'm with you there, Jon. Last night, before going to work, I observed Mars
and Luna through my Synta 66 degree bargains (6mm & 9mm) and through my
12.5mm & 7.5mm Sirius plossls (50 degree). The side by side comparison was
astonishing. . .yet I remember how impressed I was with the plossls FOV that
were an upgrade from my Meade MA kellners.


--
Martin
Remove "ilikestars" from email address to reply

Jon Isaacs wrote:

snip
I have gotten used to the wider fields of view so viewing through a Plossl
seems like looking down a drain pipe.
unsnip


I'm with you there, Jon. Last night, before going to work, I observed Mars
and Luna through my Synta 66 degree bargains (6mm & 9mm) and through my
12.5mm & 7.5mm Sirius plossls (50 degree). The side by side comparison was
astonishing. . .yet I remember how impressed I was with the plossls FOV that
were an upgrade from my Meade MA kellners.


--
Martin
Remove "ilikestars" from email address to reply

Tony Flanders wrote:
Here are the results of a "poll" that I initiated in the
middle of a thread with the dopey title "What's so Great
about Tele Vue Eyepieces?" I was hoping to get some sense
of the value that people place on a wide AFOV by presenting
the following choice:

Suppose you had to spend the rest of your life on a desert
island with one of the following sets of equipment, which
would you choose?

* An 8-inch scope with a full set of 80-degree-AFOV EPs.
* A 10-inch scope with a full set of 50-degree-AFOV EPs.


Since I have 80 AFOV eyepiece my 80 years old father have less of
difficulties of looking at my scope. Therfore, my choice would be
8inches with 80 AFOV eyepieces to allow me to observe until the end of
my days ;-)

Tony Flanders wrote:
Here are the results of a "poll" that I initiated in the
middle of a thread with the dopey title "What's so Great
about Tele Vue Eyepieces?" I was hoping to get some sense
of the value that people place on a wide AFOV by presenting
the following choice:

Suppose you had to spend the rest of your life on a desert
island with one of the following sets of equipment, which
would you choose?

* An 8-inch scope with a full set of 80-degree-AFOV EPs.
* A 10-inch scope with a full set of 50-degree-AFOV EPs.


Since I have 80 AFOV eyepiece my 80 years old father have less of
difficulties of looking at my scope. Therfore, my choice would be
8inches with 80 AFOV eyepieces to allow me to observe until the end of
my days ;-)

Tony Flanders wrote:
[I wrote:]
Given the choice between the binocs under pristine skies and a 12-inch
under heavily light-polluted skies, I'd take the binocs under dark skies
without hesitation. And it wouldn't be a choice based on aesthetics. It
would be based on the superior performance of the smaller aperture
under truly dark skies.

Think so? I would agree with you if the dark-sky instrument were, say,
a 100mm scope. But the best dark-sky subjects are galaxies, and 10x50
binoculars are simply too small to show any detail in most galaxies.
Sure, I can *detect* mag 9 galaxies in my 10x50 binoculars under dark
skies, but that's about the end of it -- they show as featureless blobs
with averted vision. Which is exactly how those same galaxies would show
in the 12-inch scope under heavy light pollution.

But for star clusters, and particularly globular clusters, the 12-inch
scope under heavy light pollution would have a *huge* advantage. Not
only do the binoculars not have enough aperture to show globular clusters
well, they also don't have enough magnification. When stating my preference
for 10x50 binoculars under dark skies, it was those globular clusters
that were hardest to give up. M5 is stupendous through a 12-inch scope
even under very heavy light pollution.

So where do the binoculars have a clear advantage? Perhaps 4 or 5 very
large nebulae, like the North America. Perhaps half a dozen galaxies,
which are big and bright enough to show real detail even in 10x50
binoculars. But for me, the crowning advantage of the binoculars
would be for viewing the biggest and best galaxy of all, namely our
own Milky Way.

Comparing the views in 10x50 binoculars used under pristine (22.0 MPSA) skies
against those in a 12-inch aperture under heavily light-polluted (18.0 MPSA)
skies, the binoculars are going to have a distinct advantage on nebulous
objects and objects large enough to require a wide field, low power view. The
telescope's advantage would be limited to small, high surface brightness
objects.

Let's begin with the Messier catalog. Among the 110 objects are nine diffuse
nebulae and open clusters associated with nebulae: M1, M8, M16, M17, M20, M24,
M42, M43 and M78. All will appear larger and more contrasty in the 10x50
binoculars under true dark skies than in a 12-inch aperture under heavy light
pollution. In fact, the nebulosity associated with M20 will probably not be
visible in 12-inch aperture. And M24--at 2-degrees in size--will not be fully
framed by the larger scope.

There are 41 galaxies, including NGC 5195 and NGC 5866, in the Messier catalog.
M31, M33 and M101 all would clearly be superior in the binoculars. And the low
surface brightness Seyfert galaxy, M74, which would be visible in the
binoculars, may not be visible in the 12-inch. Among the other spirals, you
simply won't see any structure in these under really bright skies. All are
visible in the binoculars. If the telescope holds an advantage it would be an
ability to detect a stellar core region.

Messier's catalog includes four planetary nebulae: M27, M57, M76 and M97.
Again, the binoculars will have an edge in contrast. These are fairly well
defined objects. The binoculars may have an edge on M27, which has some
delicate outlying nebulosity. The 12-inch would have a clear edge with M57,
which is a classic example of a small, bright and well-defined object.

The Messier globulars (29) are another example of large, high surface
brightness object where the telescope would still hold an edge.

Excluding those open star clusters associated with nebulosity, the Messier
catalog includes 28 such objects. Four (M7, M41, M44 and M45) are 54' or larger
in diameter. They would require at least a 1.5-degree true field to fully
encompass with a reasonable amount of sky as framework. The sky brightness in
the 12-inch at such a low magnification would be overwhelming. You'll see more
stars in these four in the binoculars.

An impressive number of objects in the Messier catalog would appear larger and
more detailed, and would show more nebulosity or more stars in the binoculars
than in the much larger telescope. This is particularly impressive when you
consider that the Messier catalog and NGC are mostly populated by objects
discovered with narrow field telescopes. If we expand our horizons, the
advantage of using binoculars under a pristine sky becomes obvious.

Large nebulae, such as the North America and the Veil, will be clearly superior
in the binoculars. The same is true for large stellar associations, such as the
Alpha Persei stellar association and the Coathanger. The summer and winter
Milky Way are filled with many such objects--not all of which have been
catalogued or been given cute common names--but all of which will be much more
detailed and interesting in the binoculars.

Comets, variable stars, meteor showers, lunar eclipses and aurorae; all will be
better viewed with the naked eye or with binoculars under a pristine sky than
with the naked eye or a 12-inch telescope under heavy light pollution.

The Messier catalog just scrapes the tip of the iceberg when it comes to
outstanding binocular objects for a true dark sky. But for large aperture under
very bright skies, you quickly start to run out of objects as soon as you leave
the Messier catalog. There's no question but that a good pair of 10x50s under
pristine skies will show far more objects than a 12-inch imprisoned by heavy
light pollution.

Regards,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
=============
Email: Remove "ic" from .comic above to respond

Tony Flanders wrote:
[I wrote:]
Given the choice between the binocs under pristine skies and a 12-inch
under heavily light-polluted skies, I'd take the binocs under dark skies
without hesitation. And it wouldn't be a choice based on aesthetics. It
would be based on the superior performance of the smaller aperture
under truly dark skies.

Think so? I would agree with you if the dark-sky instrument were, say,
a 100mm scope. But the best dark-sky subjects are galaxies, and 10x50
binoculars are simply too small to show any detail in most galaxies.
Sure, I can *detect* mag 9 galaxies in my 10x50 binoculars under dark
skies, but that's about the end of it -- they show as featureless blobs
with averted vision. Which is exactly how those same galaxies would show
in the 12-inch scope under heavy light pollution.

But for star clusters, and particularly globular clusters, the 12-inch
scope under heavy light pollution would have a *huge* advantage. Not
only do the binoculars not have enough aperture to show globular clusters
well, they also don't have enough magnification. When stating my preference
for 10x50 binoculars under dark skies, it was those globular clusters
that were hardest to give up. M5 is stupendous through a 12-inch scope
even under very heavy light pollution.

So where do the binoculars have a clear advantage? Perhaps 4 or 5 very
large nebulae, like the North America. Perhaps half a dozen galaxies,
which are big and bright enough to show real detail even in 10x50
binoculars. But for me, the crowning advantage of the binoculars
would be for viewing the biggest and best galaxy of all, namely our
own Milky Way.

Comparing the views in 10x50 binoculars used under pristine (22.0 MPSA) skies
against those in a 12-inch aperture under heavily light-polluted (18.0 MPSA)
skies, the binoculars are going to have a distinct advantage on nebulous
objects and objects large enough to require a wide field, low power view. The
telescope's advantage would be limited to small, high surface brightness
objects.

Let's begin with the Messier catalog. Among the 110 objects are nine diffuse
nebulae and open clusters associated with nebulae: M1, M8, M16, M17, M20, M24,
M42, M43 and M78. All will appear larger and more contrasty in the 10x50
binoculars under true dark skies than in a 12-inch aperture under heavy light
pollution. In fact, the nebulosity associated with M20 will probably not be
visible in 12-inch aperture. And M24--at 2-degrees in size--will not be fully
framed by the larger scope.

There are 41 galaxies, including NGC 5195 and NGC 5866, in the Messier catalog.
M31, M33 and M101 all would clearly be superior in the binoculars. And the low
surface brightness Seyfert galaxy, M74, which would be visible in the
binoculars, may not be visible in the 12-inch. Among the other spirals, you
simply won't see any structure in these under really bright skies. All are
visible in the binoculars. If the telescope holds an advantage it would be an
ability to detect a stellar core region.

Messier's catalog includes four planetary nebulae: M27, M57, M76 and M97.
Again, the binoculars will have an edge in contrast. These are fairly well
defined objects. The binoculars may have an edge on M27, which has some
delicate outlying nebulosity. The 12-inch would have a clear edge with M57,
which is a classic example of a small, bright and well-defined object.

The Messier globulars (29) are another example of large, high surface
brightness object where the telescope would still hold an edge.

Excluding those open star clusters associated with nebulosity, the Messier
catalog includes 28 such objects. Four (M7, M41, M44 and M45) are 54' or larger
in diameter. They would require at least a 1.5-degree true field to fully
encompass with a reasonable amount of sky as framework. The sky brightness in
the 12-inch at such a low magnification would be overwhelming. You'll see more
stars in these four in the binoculars.

An impressive number of objects in the Messier catalog would appear larger and
more detailed, and would show more nebulosity or more stars in the binoculars
than in the much larger telescope. This is particularly impressive when you
consider that the Messier catalog and NGC are mostly populated by objects
discovered with narrow field telescopes. If we expand our horizons, the
advantage of using binoculars under a pristine sky becomes obvious.

Large nebulae, such as the North America and the Veil, will be clearly superior
in the binoculars. The same is true for large stellar associations, such as the
Alpha Persei stellar association and the Coathanger. The summer and winter
Milky Way are filled with many such objects--not all of which have been
catalogued or been given cute common names--but all of which will be much more
detailed and interesting in the binoculars.

Comets, variable stars, meteor showers, lunar eclipses and aurorae; all will be
better viewed with the naked eye or with binoculars under a pristine sky than
with the naked eye or a 12-inch telescope under heavy light pollution.

The Messier catalog just scrapes the tip of the iceberg when it comes to
outstanding binocular objects for a true dark sky. But for large aperture under
very bright skies, you quickly start to run out of objects as soon as you leave
the Messier catalog. There's no question but that a good pair of 10x50s under
pristine skies will show far more objects than a 12-inch imprisoned by heavy
light pollution.

Regards,

Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
=============
Email: Remove "ic" from .comic above to respond

Hello, Tony,

Tony Flanders wrote:

c (Bill Ferris) wrote in message ...

Given the choice between the binocs under pristine skies and a 12-inch under
heavily light-polluted skies, I'd take the binocs under dark skies without
hesitation. And it wouldn't be a choice based on aesthetics. It would be based
on the superior performance of the smaller aperture under truly dark skies.

Think so? I would agree with you if the dark-sky instrument were, say,
a 100mm scope. But the best dark-sky subjects are galaxies, and 10x50
binoculars are simply too small to show any detail in most galaxies.
Sure, I can *detect* mag 9 galaxies in my 10x50 binoculars under dark
skies, but that's about the end of it -- they show as featureless blobs
with averted vision. Which is exactly how those same galaxies would show
in the 12-inch scope under heavy light pollution.

And which is exactly how much fainter galaxies show up in very large telescopes. You have put your finger on a
much broader issue: "detect" is the right word, and the question in my mind is, why "detect" a long series of
objects with averted vision, unless a particular object is intrinsically interesting( (for example, the
Sagittarius dwarf, or a quasar) beyond the many many many similar objects in its class? Is it the thrill of
the hunt that drives people through the Herschel II list?



But for star clusters, and particularly globular clusters, the 12-inch
scope under heavy light pollution would have a *huge* advantage. Not
only do the binoculars not have enough aperture to show globular clusters
well, they also don't have enough magnification. When stating my preference
for 10x50 binoculars under dark skies, it was those globular clusters
that were hardest to give up. M5 is stupendous through a 12-inch scope
even under very heavy light pollution.

I agree with you pretty much but "chacun a son gout" M5 is also stupendous with a 4 inch scope at 17x in my
view.



So where do the binoculars have a clear advantage? Perhaps 4 or 5 very
large nebulae, like the North America. Perhaps half a dozen galaxies,
which are big and bright enough to show real detail even in 10x50
binoculars. But for me, the crowning advantage of the binoculars
would be for viewing the biggest and best galaxy of all, namely our
own Milky Way.



Clear skies,
Bill Meyers

Hello, Tony,

Tony Flanders wrote:

c (Bill Ferris) wrote in message ...

Given the choice between the binocs under pristine skies and a 12-inch under
heavily light-polluted skies, I'd take the binocs under dark skies without
hesitation. And it wouldn't be a choice based on aesthetics. It would be based
on the superior performance of the smaller aperture under truly dark skies.

Think so? I would agree with you if the dark-sky instrument were, say,
a 100mm scope. But the best dark-sky subjects are galaxies, and 10x50
binoculars are simply too small to show any detail in most galaxies.
Sure, I can *detect* mag 9 galaxies in my 10x50 binoculars under dark
skies, but that's about the end of it -- they show as featureless blobs
with averted vision. Which is exactly how those same galaxies would show
in the 12-inch scope under heavy light pollution.

And which is exactly how much fainter galaxies show up in very large telescopes. You have put your finger on a
much broader issue: "detect" is the right word, and the question in my mind is, why "detect" a long series of
objects with averted vision, unless a particular object is intrinsically interesting( (for example, the
Sagittarius dwarf, or a quasar) beyond the many many many similar objects in its class? Is it the thrill of
the hunt that drives people through the Herschel II list?



But for star clusters, and particularly globular clusters, the 12-inch
scope under heavy light pollution would have a *huge* advantage. Not
only do the binoculars not have enough aperture to show globular clusters
well, they also don't have enough magnification. When stating my preference
for 10x50 binoculars under dark skies, it was those globular clusters
that were hardest to give up. M5 is stupendous through a 12-inch scope
even under very heavy light pollution.

I agree with you pretty much but "chacun a son gout" M5 is also stupendous with a 4 inch scope at 17x in my
view.



So where do the binoculars have a clear advantage? Perhaps 4 or 5 very
large nebulae, like the North America. Perhaps half a dozen galaxies,
which are big and bright enough to show real detail even in 10x50
binoculars. But for me, the crowning advantage of the binoculars
would be for viewing the biggest and best galaxy of all, namely our
own Milky Way.



Clear skies,
Bill Meyers

Hello, Jon,
My opinion as well.
Clear skies,
Bill Meyers,


Jon Isaacs wrote:

* One person (Jon Isaacs) refuses to take the bait; apples are apples, oranges
are oranges, and he'll deal with the desert island when and if he has to.

My solution: Pragmatic, take the 10 inch and buy those Synta 66 degree FOV
eyepieces for the less than the cost of TV Plossls. Yeah, I know its cheating
but its what I have done anyway, I am pretty happy with the Synta Ultrawides.

I am in the position of having both 8 and 10 inch scopes, I have a pretty good
idea of the difference and it is a tough call because that 50 percent extra
mirror area is pretty nice but I have gotten used to the wider fields of view
so viewing through a Plossl seems like looking down a drain pipe.

Jon