About a $3300 loss on this scope. I've seen people selling the six inch Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
https://www.cloudynights.com/classifieds/item/291342-tele-vue-np127is-nagler-petzval-apo-refractor-with-many-imaging-accessories/
On Monday, March 28, 2022 at 3:42:15 PM UTC-7, RichA wrote:
About a $3300 loss on this scope. I've seen people selling the six inch Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
https://www.cloudynights.com/classifieds/item/291342-tele-vue-np127is-nagler-petzval-apo-refractor-with-many-imaging-accessories/Even this loose value over time as it ages! https://yt3.ggpht.com/KKvivuCEtDKnysdJd7am2Ltz7etooE8hfXltiF7mT-yH6xzi368OLOZUJPqYFRfELkMwYtAXqfuj=s800-nd-v1
On Tuesday, 29 March 2022 at 20:52:01 UTC-4, StarDust wrote:
On Monday, March 28, 2022 at 3:42:15 PM UTC-7, RichA wrote:
About a $3300 loss on this scope. I've seen people selling the six inch Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
Scopes are timeless. Camgirls (?) aren't.https://www.cloudynights.com/classifieds/item/291342-tele-vue-np127is-nagler-petzval-apo-refractor-with-many-imaging-accessories/Even this loose value over time as it ages! https://yt3.ggpht.com/KKvivuCEtDKnysdJd7am2Ltz7etooE8hfXltiF7mT-yH6xzi368OLOZUJPqYFRfELkMwYtAXqfuj=s800-nd-v1
About a $3300 loss on this scope. I've seen people selling the six inch Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
On Monday, March 28, 2022 at 4:42:15 PM UTC-6, RichA wrote:
About a $3300 loss on this scope. I've seen people selling the six inch Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.I _was_ about to ask if the TeleVue scopes at least, and possibly even the Chinese ones,
The American and European and Takahashi high-end refractors fare better on resale in most cases.
were a good value _after_ their previous owners took such a loss on them.
But then I realized that to utter "value" in the same breath with "apochromatic
refractor" is to speak an oxymoron. If you want a telescope that is a good value, you want a reflecting telescope. Or, if you insist on the convenience of a sealed tube and compact size, get a Schmidt-Cassegrain.
But even high-quality Schmidt-Cassegrain telescopes used to be categorized
as not having the greatest optical quality. Since the halcyon days of the 1960s,
however, both Meade and Celestron have come out with coma-corrected designs; even if they're a bit more expensive than their regular Schmidt-Cassegrains.
Of course, if one wants a "high quality" catadioptric telescope, the traditional choice has been a Gabor-Penning telescope, particularly the Gregory-Gabor-Penning. Or the Gregory-Bouwers-Gabor-Penning. (This
telescope used to be known by another name* before the invasion of
Ukraine.)
And there are other exotic designs. In doing the web search that turned
up the work of Gabor and Penning (I had heard of _Bouwers_ before,
and was looking to be reminded of _his_ name) I learned of an interesting design by Hamilton from 1814.
This telescope had a thin crown objective, and a flint Mangin mirror.
While spherical aberration was corrected, it suffered from lateral color. A web site mentioning it shows that a significant improvement can be
achieved with a convex correcting lens, and it is mentioned that an
even better correction can be achieved with a three-lens corrector.
John Savard
*Actually, I'd be willing to settle for just renaming it to the Maksutoff telescope. This would promote pronouncing Dimitri Maksutoff's name
correctly, and would dissociate him from the anti-Western era of
Russian history.
One would probably have to go back to transliterating his name from
Old Church Slavonic, though, to go back before the era during which
Russia engaged in hegemonic actions towards Ukraine, since _that_
dates back to Peter the Great, _at least_.
About a $3300 loss on this scope. I've seen people selling the six inch >Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
https://www.cloudynights.com/classifieds/item/291342-tele-vue-np127is-nagler-petzval-apo-refractor-with-many-imaging-accessories/
What I buy is based on specs and price and intended use. Not on any
possible future retail value.
The big problem with most of these exotic designs is that that are generally limited to modest apertures, either because of the expense or impracticality.
When all is said and done, the plain-old 6-inch f/6 or f/8 Newtonian starts to look rather good.
However, looking around a bit more, I found another site
that was less bad...
10" Dobsonian - $850
12" Go-To Dobsonian - $2,560
14" Go-To Dobsonian - $3,615
16" Go-To Dobsonian - $4,680
so 10" isn't the ultimate limit these days on the aperture
available to the amateur, as I had feared at first.
On Mon, 28 Mar 2022 15:42:14 -0700 (PDT), RichA <rander3128@gmail.com>
wrote:
About a $3300 loss on this scope. I've seen people selling the six inch
Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
https://www.cloudynights.com/classifieds/item/291342-tele-vue-np127is-nagler-petzval-apo-refractor-with-many-imaging-accessories/
What I buy is based on specs and price and intended use. Not on any
possible future retail value.
So if we're talking about removing the constraints of aperture with
a Newtonian, we're talking about an f/5 or faster Dobsonian,
not about the old faithful sentimental favorites. And we don't have
Coulter Optical to order from any more...
On Friday, April 1, 2022 at 11:22:14 AM UTC-6, Chris L Peterson wrote:
What I buy is based on specs and price and intended use. Not on any
possible future retail value.
It's true that resale value is... uncertain. However, resale value does >affect the _effective_ price of a telescope if, while you are enjoying
that scope, you are also saving your money to eventually buy an
even bigger one to sate your aperture fever. Being able to realize some
cash from selling your old 'scope helps.
Which _is_ a common pattern for many amateur astronomers, even
if _you_ are above that sort of thing.
On Mon, 28 Mar 2022 15:42:14 -0700 (PDT), RichA <rande...@gmail.com>
wrote:
About a $3300 loss on this scope. I've seen people selling the six inch >Chinese Esprit scopes and being hit with $4000 losses. TeleVue scopes don't hold value and neither in most cases do the Chinese "high-end" scopes.
The American and European and Takahashi high-end refractors fare better on resale in most cases.
https://www.cloudynights.com/classifieds/item/291342-tele-vue-np127is-nagler-petzval-apo-refractor-with-many-imaging-accessories/What I buy is based on specs and price and intended use. Not on any
possible future retail value.
On Friday, April 1, 2022 at 11:06:54 AM UTC-6, W wrote:
The big problem with most of these exotic designs is that that are generally limited to modest apertures, either because of the expense or impracticality.
When all is said and done, the plain-old 6-inch f/6 or f/8 Newtonian starts to look rather good.True enough, but a Mak or a Schmidt-Cassegrain are considerably
_less_ expensive per inch of aperture than an apo... so, if for
some reason, an amateur wishes to go for the convenience of a
sealed-tube design, choosing one of those is at least a _step_ in
the direction of sanity, even if the plain old Newtonian would have
been even better.
But the 6-inch f/8 and the 8-inch f/6 of yore are _also_ limited in
aperture, to 6 inches and 8 inches respectively. You can buy a
C14 if your pockets are deep enough.
So if we're talking about removing the constraints of aperture with
a Newtonian, we're talking about an f/5 or faster Dobsonian,
not about the old faithful sentimental favorites. And we don't have
Coulter Optical to order from any more...
John Savard
On Friday, April 1, 2022 at 1:50:19 PM UTC-4, Quadibloc wrote:
On Friday, April 1, 2022 at 11:06:54 AM UTC-6, W wrote:
The big problem with most of these exotic designs is that that are generally limited to modest apertures, either because of the expense or impracticality.True enough, but a Mak or a Schmidt-Cassegrain are considerably
When all is said and done, the plain-old 6-inch f/6 or f/8 Newtonian starts to look rather good.
_less_ expensive per inch of aperture than an apo... so, if for
some reason, an amateur wishes to go for the convenience of a
sealed-tube design, choosing one of those is at least a _step_ in
the direction of sanity, even if the plain old Newtonian would have
been even better.
But the 6-inch f/8 and the 8-inch f/6 of yore are _also_ limited in
aperture, to 6 inches and 8 inches respectively. You can buy a
C14 if your pockets are deep enough.
So if we're talking about removing the constraints of aperture with
a Newtonian, we're talking about an f/5 or faster Dobsonian,
not about the old faithful sentimental favorites. And we don't have
Coulter Optical to order from any more...
John Savard
Twisting my words a bit!
A C-14 has a very long focal length and will not compete very well with an 18-inch f5 Newt, except maybe in a college observatory somewhere, where the agenda are a bit different anyway.
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
No.Your test is meaningless without specifying the focal length of the
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
telescope and the eyepiece.
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote:
On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:Your test is meaningless without specifying the focal length of the
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
telescope and the eyepiece.
The magnification was specified: 100x.
On Sun, 3 Apr 2022 04:42:51 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote:
On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote: >> >Your test is meaningless without specifying the focal length of the
Aperture is everything for imaging. But for visual? You're never going >> >> to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification >> >> before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
telescope and the eyepiece.
The magnification was specified: 100x.Which is the point. You can choose a scenario where the aperture
benefits you. And you can choose one where it doesn't. Which is why
you can't make any blanket statement about the value of aperture in a telescope used visually.
On Sunday, April 3, 2022 at 9:47:41 AM UTC-4, Chris L Peterson wrote:
On Sun, 3 Apr 2022 04:42:51 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote:Which is the point. You can choose a scenario where the aperture
On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote: >> >> >Your test is meaningless without specifying the focal length of the
Aperture is everything for imaging. But for visual? You're never going >> >> >> to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification >> >> >> before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture >> >> >> is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
telescope and the eyepiece.
The magnification was specified: 100x.
benefits you. And you can choose one where it doesn't. Which is why
you can't make any blanket statement about the value of aperture in a
telescope used visually.
No, you missed the point. At any given magnification, the more light, the better with regard to visual astronomy, an exception being white-light solar observing.
The way that you will get more light is by using more aperture.
And we are comparing either a 14-inch with an 18-inch, or more dramatically, a 2.4-inch with an 18-inch.
On Sun, 3 Apr 2022 12:43:44 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Sunday, April 3, 2022 at 9:47:41 AM UTC-4, Chris L Peterson wrote:
On Sun, 3 Apr 2022 04:42:51 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote: >> >> On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>Which is the point. You can choose a scenario where the aperture
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:Your test is meaningless without specifying the focal length of the
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What >> >> >> aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets >> >> >> you're interested in require high magnification. Otherwise, aperture >> >> >> is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
telescope and the eyepiece.
The magnification was specified: 100x.
benefits you. And you can choose one where it doesn't. Which is why
you can't make any blanket statement about the value of aperture in a
telescope used visually.
No, you missed the point. At any given magnification, the more light, the better with regard to visual astronomy, an exception being white-light solar observing.
The way that you will get more light is by using more aperture.
And we are comparing either a 14-inch with an 18-inch, or more dramatically, a 2.4-inch with an 18-inch.A larger aperture will not necessarily place more light in your eye.
Consider, for instance, a 1000mm FL telescope used with a 25mm EP (so,
40X magnification). A typical observer will certainly get a brighter
image with a 200mm aperture than a 100mm aperture. But going to 300mm
or 400mm will make no difference.
There's a reason people don't make 8X100 binoculars!
On Sunday, April 3, 2022 at 5:43:27 PM UTC-4, Chris L Peterson wrote:
On Sun, 3 Apr 2022 12:43:44 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Sunday, April 3, 2022 at 9:47:41 AM UTC-4, Chris L Peterson wrote:A larger aperture will not necessarily place more light in your eye.
On Sun, 3 Apr 2022 04:42:51 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote: >> >> >> On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>Which is the point. You can choose a scenario where the aperture
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:Your test is meaningless without specifying the focal length of the
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What >> >> >> >> aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets >> >> >> >> you're interested in require high magnification. Otherwise, aperture
is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
telescope and the eyepiece.
The magnification was specified: 100x.
benefits you. And you can choose one where it doesn't. Which is why
you can't make any blanket statement about the value of aperture in a
telescope used visually.
No, you missed the point. At any given magnification, the more light, the better with regard to visual astronomy, an exception being white-light solar observing.
The way that you will get more light is by using more aperture.
And we are comparing either a 14-inch with an 18-inch, or more dramatically, a 2.4-inch with an 18-inch.
Consider, for instance, a 1000mm FL telescope used with a 25mm EP (so,
40X magnification). A typical observer will certainly get a brighter
image with a 200mm aperture than a 100mm aperture. But going to 300mm
or 400mm will make no difference.
There's a reason people don't make 8X100 binoculars!
You are disagreeing with something that I didn't even say!
Your statement about the 300mm is clearly in error.
The global average of the maximum pupil diameter is around 6.5 mm.
So using 40x will result in an effective aperture of 260mm for that average person.
Clearly, that is an improvement in light-gathering power over a 200mm!
And there are some people who exceed a 7 mm pupil by a fair margin.
On Tue, 5 Apr 2022 12:22:31 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Sunday, April 3, 2022 at 5:43:27 PM UTC-4, Chris L Peterson wrote:
On Sun, 3 Apr 2022 12:43:44 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Sunday, April 3, 2022 at 9:47:41 AM UTC-4, Chris L Peterson wrote:A larger aperture will not necessarily place more light in your eye.
On Sun, 3 Apr 2022 04:42:51 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote:Which is the point. You can choose a scenario where the aperture
On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:Your test is meaningless without specifying the focal length of the >> >> >> telescope and the eyepiece.
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
The magnification was specified: 100x.
benefits you. And you can choose one where it doesn't. Which is why
you can't make any blanket statement about the value of aperture in a >> >> telescope used visually.
No, you missed the point. At any given magnification, the more light, the better with regard to visual astronomy, an exception being white-light solar observing.
The way that you will get more light is by using more aperture.
And we are comparing either a 14-inch with an 18-inch, or more dramatically, a 2.4-inch with an 18-inch.
Consider, for instance, a 1000mm FL telescope used with a 25mm EP (so,
40X magnification). A typical observer will certainly get a brighter
image with a 200mm aperture than a 100mm aperture. But going to 300mm
or 400mm will make no difference.
There's a reason people don't make 8X100 binoculars!
You are disagreeing with something that I didn't even say!
Your statement about the 300mm is clearly in error.
The global average of the maximum pupil diameter is around 6.5 mm.
So using 40x will result in an effective aperture of 260mm for that average person.
Clearly, that is an improvement in light-gathering power over a 200mm!
And there are some people who exceed a 7 mm pupil by a fair margin.I'm using 5mm, which is probably more accurate for most amateur
astronomers. But it doesn't really matter what number you use, the
principle is the same, which is that for any given magnification,
there is a point where adding aperture will have no effect.
I'm using 5mm, which is probably more accurate for most amateur
astronomers. But it doesn't really matter what number you use, the
principle is the same, which is that for any given magnification,
there is a point where adding aperture will have no effect.
On Tuesday, April 5, 2022 at 2:47:55 PM UTC-6, Chris L Peterson wrote:
I'm using 5mm, which is probably more accurate for most amateur
astronomers. But it doesn't really matter what number you use, the
principle is the same, which is that for any given magnification,
there is a point where adding aperture will have no effect.
That's true, but is that the same as saying that adding aperture will
have no effect, period?
When looking at extended objects like the Moon or Mars, there is a
maximum reasonable magnification, where all available detail is
easily visible.
But while the brightness of extended objects can't be increased lby
adding aperture, *point objects* like stars _can_ be made brighter by
adding aperture precisely because doing so makes greater magnification >possible.
On Tuesday, April 5, 2022 at 2:47:55 PM UTC-6, Chris L Peterson wrote:
I'm using 5mm, which is probably more accurate for most amateur astronomers. But it doesn't really matter what number you use, the principle is the same, which is that for any given magnification,That's true, but is that the same as saying that adding aperture will
there is a point where adding aperture will have no effect.
have no effect, period?
When looking at extended objects like the Moon or Mars, there is a
maximum reasonable magnification, where all available detail is
easily visible.
But while the brightness of extended objects can't be increased lby
adding aperture, *point objects* like stars _can_ be made brighter by
adding aperture precisely because doing so makes greater magnification possible.
John Savard
On Wed, 6 Apr 2022 08:26:01 -0700 (PDT), Quadibloc <jsa...@ecn.ab.ca>
wrote:
On Tuesday, April 5, 2022 at 2:47:55 PM UTC-6, Chris L Peterson wrote:
I'm using 5mm, which is probably more accurate for most amateur
astronomers. But it doesn't really matter what number you use, the
principle is the same, which is that for any given magnification,
there is a point where adding aperture will have no effect.
That's true, but is that the same as saying that adding aperture will
have no effect, period?
When looking at extended objects like the Moon or Mars, there is a
maximum reasonable magnification, where all available detail is
easily visible.
But while the brightness of extended objects can't be increased lbySure. But my point is the same. For any object type at all, and any
adding aperture, *point objects* like stars _can_ be made brighter by >adding aperture precisely because doing so makes greater magnification >possible.
given magnification, there is a point at which adding aperture will
provide no difference. This is in response to W's blanket claim that
more aperture always benefits a visual observer. That is patently
false.
On Wed, 6 Apr 2022 08:26:01 -0700 (PDT), Quadibloc <jsavard@ecn.ab.ca>
wrote:
On Tuesday, April 5, 2022 at 2:47:55 PM UTC-6, Chris L Peterson wrote:
I'm using 5mm, which is probably more accurate for most amateur
astronomers. But it doesn't really matter what number you use, the
principle is the same, which is that for any given magnification,
there is a point where adding aperture will have no effect.
That's true, but is that the same as saying that adding aperture will
have no effect, period?
When looking at extended objects like the Moon or Mars, there is a
maximum reasonable magnification, where all available detail is
easily visible.
But while the brightness of extended objects can't be increased lby
adding aperture, *point objects* like stars _can_ be made brighter by
adding aperture precisely because doing so makes greater magnification
possible.
Sure. But my point is the same. For any object type at all, and any
given magnification, there is a point at which adding aperture will
provide no difference. This is in response to W's blanket claim that
more aperture always benefits a visual observer. That is patently
false.
On Tue, 5 Apr 2022 12:22:31 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Sunday, April 3, 2022 at 5:43:27 PM UTC-4, Chris L Peterson wrote:
On Sun, 3 Apr 2022 12:43:44 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Sunday, April 3, 2022 at 9:47:41 AM UTC-4, Chris L Peterson wrote:A larger aperture will not necessarily place more light in your eye.
On Sun, 3 Apr 2022 04:42:51 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 10:39:24 PM UTC-4, Chris L Peterson wrote:Which is the point. You can choose a scenario where the aperture
On Sat, 2 Apr 2022 15:37:01 -0700 (PDT), W <wsne...@hotmail.com>
wrote:
On Saturday, April 2, 2022 at 6:02:55 PM UTC-4, Chris L Peterson wrote:Your test is meaningless without specifying the focal length of the >> >> >> telescope and the eyepiece.
Aperture is everything for imaging. But for visual? You're never going
to get anything brighter than it appears without a telescope. What
aperture buys you is the ability to operate at a higher magnification
before you start losing light. Which is important... if the targets
you're interested in require high magnification. Otherwise, aperture
is wasted.
No.
Compare an 18-inch at 100x with a 2.4-inch at 100x, side by side, same type of eyepiece, same object, both used visually.
The magnification was specified: 100x.
benefits you. And you can choose one where it doesn't. Which is why
you can't make any blanket statement about the value of aperture in a >> >> telescope used visually.
No, you missed the point. At any given magnification, the more light, the better with regard to visual astronomy, an exception being white-light solar observing.
The way that you will get more light is by using more aperture.
And we are comparing either a 14-inch with an 18-inch, or more dramatically, a 2.4-inch with an 18-inch.
Consider, for instance, a 1000mm FL telescope used with a 25mm EP (so,
40X magnification). A typical observer will certainly get a brighter
image with a 200mm aperture than a 100mm aperture. But going to 300mm
or 400mm will make no difference.
There's a reason people don't make 8X100 binoculars!
You are disagreeing with something that I didn't even say!
Your statement about the 300mm is clearly in error.
The global average of the maximum pupil diameter is around 6.5 mm.
So using 40x will result in an effective aperture of 260mm for that average person.
Clearly, that is an improvement in light-gathering power over a 200mm!
And there are some people who exceed a 7 mm pupil by a fair margin.I'm using 5mm, which is probably more accurate for most amateur
astronomers. But it doesn't really matter what number you use, the
principle is the same, which is that for any given magnification,
there is a point where adding aperture will have no effect.
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